Damage Identification of a Derrick Steel Structure Based on the HHT Marginal Spectrum Amplitude Curvature Difference

Directory of Open Access Journals (Sweden)

Dongying Han

2017-01-01

Full Text Available For the damage identification of derrick steel structures, traditional methods often require high-order vibration information of structures to identify damage accurately. However, the high-order vibration information of structures is difficult to acquire. Based on the technology of signal feature extraction, only using the low-order vibration information, taking the right front leg as an example, we analyzed the selection of HHT marginal spectrum amplitude and the calculation process of its curvature in practical application, designed the damage conditions of a derrick steel structure, used the index and intrinsic mode function (IMF instantaneous energy curvature method to perform the damage simulation calculation and comparison, and verified the effect of identifying the damage location in a noisy environment. The results show that the index can accurately determine the location of the damage element and weak damage element and can be used to qualitatively analyze the damage degree of the element; under the impact load, the noise hardly affects the identification of the damage location. Finally, this method was applied to the ZJ70 derrick steel structure laboratory model and compared with the IMF instantaneous energy curvature method. We verified the feasibility of this method in the damage location simulation experiment.

Frequency Response Function Based Damage Identification for Aerospace Structures

Science.gov (United States)

Oliver, Joseph Acton

Structural health monitoring technologies continue to be pursued for aerospace structures in the interests of increased safety and, when combined with health prognosis, efficiency in life-cycle management. The current dissertation develops and validates damage identification technology as a critical component for structural health monitoring of aerospace structures and, in particular, composite unmanned aerial vehicles. The primary innovation is a statistical least-squares damage identification algorithm based in concepts of parameter estimation and model update. The algorithm uses frequency response function based residual force vectors derived from distributed vibration measurements to update a structural finite element model through statistically weighted least-squares minimization producing location and quantification of the damage, estimation uncertainty, and an updated model. Advantages compared to other approaches include robust applicability to systems which are heavily damped, large, and noisy, with a relatively low number of distributed measurement points compared to the number of analytical degrees-of-freedom of an associated analytical structural model (e.g., modal finite element model). Motivation, research objectives, and a dissertation summary are discussed in Chapter 1 followed by a literature review in Chapter 2. Chapter 3 gives background theory and the damage identification algorithm derivation followed by a study of fundamental algorithm behavior on a two degree-of-freedom mass-spring system with generalized damping. Chapter 4 investigates the impact of noise then successfully proves the algorithm against competing methods using an analytical eight degree-of-freedom mass-spring system with non-proportional structural damping. Chapter 5 extends use of the algorithm to finite element models, including solutions for numerical issues, approaches for modeling damping approximately in reduced coordinates, and analytical validation using a composite

Research on Damage Identification of Bridge Based on Digital Image Measurement

Science.gov (United States)

Liang, Yingjing; Huan, Shi; Tao, Weijun

2017-12-01

In recent years, the number of the damage bridge due to excessive deformation gradually increased, which caused significant property damage and casualties. Hence health monitoring and the damage detection of the bridge structure based on the deflection measurement are particularly important. The current conventional deflection measurement methods, such as total station, connected pipe, GPS, etc., have many shortcomings as low efficiency, heavy workload, low degree of automation, operating frequency and working time constrained. GPS has a low accuracy in the vertical displacement measurement and cannot meet the dynamic measured requirements of the current bridge engineering. This paper presents a bridge health monitoring and damage detection technology based on digital image measurement method in which the measurement accuracy is sub-millimeter level and can achieve the 24-hour automatic non-destructive monitoring for the deflection. It can be concluded from this paper that it is feasible to use digital image measurement method for identification of the damage in the bridge structure, because it has been validated by the theoretical analysis, the laboratory model and the application of the real bridge.

Statistical time series methods for damage diagnosis in a scale aircraft skeleton structure: loosened bolts damage scenarios

International Nuclear Information System (INIS)

Kopsaftopoulos, Fotis P; Fassois, Spilios D

2011-01-01

A comparative assessment of several vibration based statistical time series methods for Structural Health Monitoring (SHM) is presented via their application to a scale aircraft skeleton laboratory structure. A brief overview of the methods, which are either scalar or vector type, non-parametric or parametric, and pertain to either the response-only or excitation-response cases, is provided. Damage diagnosis, including both the detection and identification subproblems, is tackled via scalar or vector vibration signals. The methods' effectiveness is assessed via repeated experiments under various damage scenarios, with each scenario corresponding to the loosening of one or more selected bolts. The results of the study confirm the 'global' damage detection capability and effectiveness of statistical time series methods for SHM.

Damage location and quantification of a pretensioned concrete beam using stochastic subspace identification

Science.gov (United States)

Cancelli, Alessandro; Micheli, Laura; Laflamme, Simon; Alipour, Alice; Sritharan, Sri; Ubertini, Filippo

2017-04-01

Stochastic subspace identification (SSID) is a first-order linear system identification technique enabling modal analysis through the time domain. Research in the field of structural health monitoring has demonstrated that SSID can be used to successfully retrieve modal properties, including modal damping ratios, using output-only measurements. In this paper, the utilization of SSID for indirectly retrieving structures' stiffness matrix was investigated, through the study of a simply supported reinforced concrete beam subjected to dynamic loads. Hence, by introducing a physical model of the structure, a second-order identification method is achieved. The reconstruction is based on system condensation methods, which enables calculation of reduced order stiffness, damping, and mass matrices for the structural system. The methods compute the reduced order matrices directly from the modal properties, obtained through the use of SSID. Lastly, the reduced properties of the system are used to reconstruct the stiffness matrix of the beam. The proposed approach is first verified through numerical simulations and then validated using experimental data obtained from a full-scale reinforced concrete beam that experienced progressive damage. Results show that the SSID technique can be used to diagnose, locate, and quantify damage through the reconstruction of the stiffness matrix.

Experimental verifications of a structural damage identification technique using reduced order finite-element model

Science.gov (United States)

Li, Rui; Zhou, Li; Yang, Jann N.

2010-04-01

An objective of the structural health monitoring system is to identify the state of the structure and to detect the damage when it occurs. Analysis techniques for the damage identification of structures, based on vibration data measured from sensors, have received considerable attention. Recently, a new damage tracking technique, referred to as the adaptive quadratic sum-square error (AQSSE) technique, has been proposed, and simulation studies demonstrated that the AQSSE technique is quite effective in identifying structural damages. In this paper, the adaptive quadratic sumsquare error (AQSSE) along with the reduced-order finite-element method is proposed to identify the damages of complex structures. Experimental tests were conducted to verify the capability of the proposed damage detection approach. A series of experimental tests were performed using a scaled cantilever beam subject to the white noise and sinusoidal excitations. The capability of the proposed reduced-order finite-element based adaptive quadratic sum-square error (AQSSE) method in detecting the structural damage is demonstrated by the experimental results.

Method for identification of fluid mixing zones subject to thermal fatigue damage

International Nuclear Information System (INIS)

Vole, O.; Beaud, F.

2009-01-01

High cycle thermal fatigue due to the mixing of hot and cold fluids may initiate cracking in pipes of safety related circuits. A method has been developed to identify such fluid mixing zones subjected to potential thermal fatigue damage. This method is based on a loading model and a mechanical model that depend on the main characteristics of the mixing zone and on the material properties. It is supported by a large experimental program. This method has been applied to all the mixing zones of safety related circuits of the EDF pressurised water reactors, allowing to identify sensitive zones and to apply an appropriate inspection program that ensures the control of the risk due to this damage mechanism. (authors)

Structural damage diagnosis based on on-line recursive stochastic subspace identification

International Nuclear Information System (INIS)

Loh, Chin-Hsiung; Weng, Jian-Huang; Liu, Yi-Cheng; Lin, Pei-Yang; Huang, Shieh-Kung

2011-01-01

This paper presents a recursive stochastic subspace identification (RSSI) technique for on-line and almost real-time structural damage diagnosis using output-only measurements. Through RSSI the time-varying natural frequencies of a system can be identified. To reduce the computation time in conducting LQ decomposition in RSSI, the Givens rotation as well as the matrix operation appending a new data set are derived. The relationship between the size of the Hankel matrix and the data length in each shifting moving window is examined so as to extract the time-varying features of the system without loss of generality and to establish on-line and almost real-time system identification. The result from the RSSI technique can also be applied to structural damage diagnosis. Off-line data-driven stochastic subspace identification was used first to establish the system matrix from the measurements of an undamaged (reference) case. Then the RSSI technique incorporating a Kalman estimator is used to extract the dynamic characteristics of the system through continuous monitoring data. The predicted residual error is defined as a damage feature and through the outlier statistics provides an indicator of damage. Verification of the proposed identification algorithm by using the bridge scouring test data and white noise response data of a reinforced concrete frame structure is conducted

Damage identification in composite panels using guided waves

NARCIS (Netherlands)

Loendersloot, R.; Moix-Bonet, M.

2015-01-01

A methodology for the identification of barely visible impact damage using guided waves on a typical aircraft composite structure is implemented. Delaminations and debondings have been introduced in two stiffened panels by means of impact loads.

Structural damage detection based on stochastic subspace identification and statistical pattern recognition: I. Theory

Science.gov (United States)

Ren, W. X.; Lin, Y. Q.; Fang, S. E.

2011-11-01

One of the key issues in vibration-based structural health monitoring is to extract the damage-sensitive but environment-insensitive features from sampled dynamic response measurements and to carry out the statistical analysis of these features for structural damage detection. A new damage feature is proposed in this paper by using the system matrices of the forward innovation model based on the covariance-driven stochastic subspace identification of a vibrating system. To overcome the variations of the system matrices, a non-singularity transposition matrix is introduced so that the system matrices are normalized to their standard forms. For reducing the effects of modeling errors, noise and environmental variations on measured structural responses, a statistical pattern recognition paradigm is incorporated into the proposed method. The Mahalanobis and Euclidean distance decision functions of the damage feature vector are adopted by defining a statistics-based damage index. The proposed structural damage detection method is verified against one numerical signal and two numerical beams. It is demonstrated that the proposed statistics-based damage index is sensitive to damage and shows some robustness to the noise and false estimation of the system ranks. The method is capable of locating damage of the beam structures under different types of excitations. The robustness of the proposed damage detection method to the variations in environmental temperature is further validated in a companion paper by a reinforced concrete beam tested in the laboratory and a full-scale arch bridge tested in the field.

Identification of damage in plates using full-field measurement with a continuously scanning laser Doppler vibrometer system

Science.gov (United States)

Chen, Da-Ming; Xu, Y. F.; Zhu, W. D.

2018-05-01

An effective and reliable damage identification method for plates with a continuously scanning laser Doppler vibrometer (CSLDV) system is proposed. A new constant-speed scan algorithm is proposed to create a two-dimensional (2D) scan trajectory and automatically scan a whole plate surface. Full-field measurement of the plate can be achieved by applying the algorithm to the CSLDV system. Based on the new scan algorithm, the demodulation method is extended from one dimension for beams to two dimensions for plates to obtain a full-field operating deflection shape (ODS) of the plate from velocity response measured by the CSLDV system. The full-field ODS of an associated undamaged plate is obtained by using polynomials with proper orders to fit the corresponding full-field ODS from the demodulation method. A curvature damage index (CDI) using differences between curvatures of ODSs (CODSs) associated with ODSs that are obtained by the demodulation method and the polynomial fit is proposed to identify damage. An auxiliary CDI obtained by averaging CDIs at different excitation frequencies is defined to further assist damage identification. An experiment of an aluminum plate with damage in the form of 10.5% thickness reduction in a damage area of 0.86% of the whole scan area is conducted to investigate the proposed method. Six frequencies close to natural frequencies of the plate and one randomly selected frequency are used as sinusoidal excitation frequencies. Two 2D scan trajectories, i.e., a horizontally moving 2D scan trajectory and a vertically moving 2D scan trajectory, are used to obtain ODSs, CODSs, and CDIs of the plate. The damage is successfully identified near areas with consistently high values of CDIs at different excitation frequencies along the two 2D scan trajectories; the damage area is also identified by auxiliary CDIs.

Application of Modal Parameter Estimation Methods for Continuous Wavelet Transform-Based Damage Detection for Beam-Like Structures

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Zhi Qiu

2015-02-01

Full Text Available This paper presents a hybrid damage detection method based on continuous wavelet transform (CWT and modal parameter identification techniques for beam-like structures. First, two kinds of mode shape estimation methods, herein referred to as the quadrature peaks picking (QPP and rational fraction polynomial (RFP methods, are used to identify the first four mode shapes of an intact beam-like structure based on the hammer/accelerometer modal experiment. The results are compared and validated using a numerical simulation with ABAQUS software. In order to determine the damage detection effectiveness between the QPP-based method and the RFP-based method when applying the CWT technique, the first two mode shapes calculated by the QPP and RFP methods are analyzed using CWT. The experiment, performed on different damage scenarios involving beam-like structures, shows that, due to the outstanding advantage of the denoising characteristic of the RFP-based (RFP-CWT technique, the RFP-CWT method gives a clearer indication of the damage location than the conventionally used QPP-based (QPP-CWT method. Finally, an overall evaluation of the damage detection is outlined, as the identification results suggest that the newly proposed RFP-CWT method is accurate and reliable in terms of detection of damage locations on beam-like structures.

Full-scale experimental validation of decentralized damage identification using wireless smart sensors

International Nuclear Information System (INIS)

Jang, Shinae; Sim, Sung-Han; Jo, Hongki; Spencer Jr, Billie F

2012-01-01

Wireless smart sensor networks (WSSN) facilitate a new paradigm for structural health monitoring (SHM) of civil infrastructure. Conventionally, SHM systems employing wired sensors and centralized data acquisition have been used to characterize the state of a structure; however, widespread implementation has been limited due to high costs and difficulties in installation. WSSN offer a unique opportunity to overcome such difficulties. Recent developments have realized low-cost, smart sensors with on-board computation and wireless communication capabilities, making deployment of a dense array of sensors on large civil structures both economical and feasible. Wireless smart sensors (WSS) have shown their tremendous potential for SHM in recent full-scale bridge monitoring examples. However, structural damage identification using on-board computation capability in a WSSN, a primary objective of SHM, has yet to reach its full potential. This paper presents full-scale validation of a damage identification strategy using a decentralized network of Imote2 nodes on a historic steel truss bridge. A total of 24 WSS nodes with 144 sensor channels are deployed on the bridge to validate the developed damage identification software. The performance of this decentralized damage identification strategy is demonstrated on the WSSN by comparing its results with those from the traditional centralized approach, as well as visual inspection. (paper)

Substructure identification for shear structures: cross-power spectral density method

International Nuclear Information System (INIS)

Zhang, Dongyu; Johnson, Erik A

2012-01-01

In this paper, a substructure identification method for shear structures is proposed. A shear structure is divided into many small substructures; utilizing the dynamic equilibrium of a one-floor substructure, an inductive identification problem is formulated, using the cross-power spectral densities between structural floor accelerations and a reference response, to estimate the parameters of that one story. Repeating this procedure, all story parameters of the shear structure are identified from top to bottom recursively. An identification error analysis is performed for the proposed substructure method, revealing how uncertain factors (e.g. measurement noise) in the identification process affect the identification accuracy. According to the error analysis, a smart reference selection rule is designed to choose the optimal reference response that further enhances the identification accuracy. Moreover, based on the identification error analysis, explicit formulae are developed to calculate the variances of the parameter identification errors. A ten-story shear structure is used to illustrate the effectiveness of the proposed substructure method. The simulation results show that the method, combined with the reference selection rule, can very accurately identify structural parameters despite large measurement noise. Furthermore, the proposed formulae provide good predictions for the variances of the parameter identification errors, which are vital for providing accurate warnings of structural damage. (paper)

A novel damage index for damage identification using guided waves with application in laminated composites

International Nuclear Information System (INIS)

Torkamani, Shahab; Roy, Samit; Barkey, Mark E; Sazonov, Edward; Burkett, Susan; Kotru, Sushma

2014-01-01

In the current investigation, an innovative time-domain damage index is introduced for the first time which is based on local statistical features of the waveform. This damage index is called the ‘normalized correlation moment’ (NCM) and is composed of the nth moment of the cross-correlation of the baseline and comparison waves. The performance of this novel damage index is compared for some synthetic signals with that of an existing damage index based on the Pearson correlation coefficient (signal difference coefficient, SDC). The proposed damage index is shown to have significant advantages over the SDC, including sensitivity to the attenuation of the signal and lower sensitivity to the signal’s noise level. Numerical simulations using Abaqus finite element (FE) software show that this novel damage index is not only capable of detecting the delamination type of damage, but also exhibits a good ability in the assessment of this type of damage in laminated composite structures. The NCM damage index is also validated using experimental data for identification of delamination in composites. (paper)

A Kriging Model Based Finite Element Model Updating Method for Damage Detection

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Xiuming Yang

2017-10-01

Full Text Available Model updating is an effective means of damage identification and surrogate modeling has attracted considerable attention for saving computational cost in finite element (FE model updating, especially for large-scale structures. In this context, a surrogate model of frequency is normally constructed for damage identification, while the frequency response function (FRF is rarely used as it usually changes dramatically with updating parameters. This paper presents a new surrogate model based model updating method taking advantage of the measured FRFs. The Frequency Domain Assurance Criterion (FDAC is used to build the objective function, whose nonlinear response surface is constructed by the Kriging model. Then, the efficient global optimization (EGO algorithm is introduced to get the model updating results. The proposed method has good accuracy and robustness, which have been verified by a numerical simulation of a cantilever and experimental test data of a laboratory three-story structure.

The development of damage identification methods for buildings with image recognition and machine learning techniques utilizing aerial photographs of the 2016 Kumamoto earthquake

Science.gov (United States)

Shohei, N.; Nakamura, H.; Fujiwara, H.; Naoichi, M.; Hiromitsu, T.

2017-12-01

It is important to get schematic information of the damage situation immediately after the earthquake utilizing photographs shot from an airplane in terms of the investigation and the decision-making for authorities. In case of the 2016 Kumamoto earthquake, we have acquired more than 1,800 orthographic projection photographs adjacent to damaged areas. These photos have taken between April 16th and 19th by airplanes, then we have distinguished damages of all buildings with 4 levels, and organized as approximately 296,000 GIS data corresponding to the fundamental Geospatial data published by Geospatial Information Authority of Japan. These data have organized by effort of hundreds of engineers. However, it is not considered practical for more extensive disasters like the Nankai Trough earthquake by only human powers. So, we have been developing the automatic damage identification method utilizing image recognition and machine learning techniques. First, we have extracted training data of more than 10,000 buildings which have equally damage levels divided in 4 grades. With these training data, we have been raster scanning in each scanning ranges of entire images, then clipping patch images which represents damage levels each. By utilizing these patch images, we have been developing discriminant models by two ways. One is a model using the Support Vector Machine (SVM). First, extract a feature quantity of each patch images. Then, with these vector values, calculate the histogram density as a method of Bag of Visual Words (BoVW), then classify borders with each damage grades by SVM. The other one is a model using the multi-layered Neural Network. First, design a multi-layered Neural Network. Second, input patch images and damage levels based on a visual judgement, and then, optimize learning parameters with error backpropagation method. By use of both discriminant models, we are going to discriminate damage levels in each patches, then create the image that shows

Current injection phase thermography for low-velocity impact damage identification in composite laminates

International Nuclear Information System (INIS)

Grammatikos, S.A.; Kordatos, E.Z.; Matikas, T.E.; David, C.; Paipetis, A.S.

2014-01-01

Highlights: • A novel Current injection phase thermography NDE method has been developed. • Blind impact damage has been successfully detected in composite laminates. • Carbon nanotubes enhance detection by improving of through thickness conductivity. • Detection is feasible with considerably less energy than for IR excited thermography. - Abstract: An innovative non-destructive evaluation (NDE) technique is presented based on current stimulated thermography. Modulated electric current is injected to Carbon Fibre Reinforced Plastics (CFRP) laminates as an external source of thermal excitation. Pulsed Phase Thermography (PPT) is concurrently employed to identify low velocity impact induced (LVI) damage. The efficiency of the proposed method is demonstrated for both plain and with Carbon Nanotubes (CNTs) modified laminates, which are subjected to low-velocity impact damaged composite laminates at different energy levels. The presence of the nano reinforcing phase is important in achieving a uniform current flow along the laminate, as it improves the through thickness conductivity. The acquired thermographs are compared with optical PPT, C-scan images and Computer Tomography (CT) representations. The typical energy input for successful damage identification with current injection is three to four orders of magnitude less compared to the energy required for optical PPT

Damage Identification of Bridge Based on Chebyshev Polynomial Fitting and Fuzzy Logic without Considering Baseline Model Parameters

Directory of Open Access Journals (Sweden)

Yu-Bo Jiao

2015-01-01

Full Text Available The paper presents an effective approach for damage identification of bridge based on Chebyshev polynomial fitting and fuzzy logic systems without considering baseline model data. The modal curvature of damaged bridge can be obtained through central difference approximation based on displacement modal shape. Depending on the modal curvature of damaged structure, Chebyshev polynomial fitting is applied to acquire the curvature of undamaged one without considering baseline parameters. Therefore, modal curvature difference can be derived and used for damage localizing. Subsequently, the normalized modal curvature difference is treated as input variable of fuzzy logic systems for damage condition assessment. Numerical simulation on a simply supported bridge was carried out to demonstrate the feasibility of the proposed method.

Vibro-acoustic modulation–based damage identification in a composite skin–stiffener structure

NARCIS (Netherlands)

Ooijevaar, T.H.; Rogge, M.D.; Loendersloot, Richard; Warnet, Laurent; Akkerman, Remko; Tinga, Tiedo

2016-01-01

Vibro-acoustic modulation–based damage identification relies on the modulation of a high-frequency carrier signal by an intenser low-frequency vibration signal due to damage-induced structural nonlinearities. A time domain analysis of the vibro-acoustic modulation phenomena was presented at multiple

Damage Identification and Seismic Vulnerability Assessment of a Historic Masonry Chimney

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Maria-Giovanna Masciotta

2017-07-01

Full Text Available The present paper deals with the dynamic characterisation of a historical masonry chimney aimed at identifying the structural damage and assessing its seismic performance. The structure was severely damaged by a lightning accident and in-depth repair works were executed to re-instate its sound configuration. The case study is fully detailed, including the aspects of survey, inspection, diagnosis, and evolution of the dynamic properties of the system throughout the structural intervention. Considering the explicit dependence of the power spectral densities of measured nodal processes on their frequency content, a spectrum-driven algorithm is used to detect and locate the damage. The paper shows that the eigenparameters obtained from the decomposition of the response power spectrum matrix are sensitive to system’s changes caused by evolutionary damage scenarios, thereby resulting excellent indicators for assessing both the presence and position of structural vulnerabilities. The results are compared with the ones from other modal-based damage identification methods and the strengths/limitations of the tools currently available in literature are extensively discussed. Finally, based on the crack pattern surveyed before the repair works, the weakest links of the chimney are identified and the most meaningful collapse mechanisms are analysed to verify the seismic capacity of the structure. According to the results of the kinematic analysis, the chimney does withstand the maximum site peak ground acceleration.

Statistical methods for damage detection applied to civil structures

DEFF Research Database (Denmark)

Gres, Szymon; Ulriksen, Martin Dalgaard; Döhler, Michael

2017-01-01

Damage detection consists of monitoring the deviations of a current system from its reference state, characterized by some nominal property repeatable for every healthy state. Preferably, the damage detection is performed directly on vibration data, hereby avoiding modal identification of the str...

Damage Identification for Prestressed Adjacent Box-Beam Bridges

Directory of Open Access Journals (Sweden)

Kenneth K. Walsh

2014-01-01

Full Text Available Structural health monitoring (SHM has gained considerable attention as a tool for monitoring the health of civil infrastructure. For bridge infrastructure, previous methods have focused on the detection of localized damage through modal parameters extracted from the longitudinal direction of the structure. This paper investigates a new damage detection method based on the change in the first vertical mode extracted from the transverse direction of the bridge. The mode is determined through application of modal curve fitting to frequency response functions (FRFs that are formed using vertical response data obtained in the direction perpendicular to the bridge’s longitudinal axis. Using this method, both local damage and global damage in the bridge reveal themselves as having a localized effect on the bridge response. Furthermore, damage is revealed in such a way that it enables differentiation of the damage types. To demonstrate the effectiveness of the method, modal parameters were extracted from acceleration data obtained from a finite element model of a full bridge. Analysis of the modal parameters showed that the proposed approach could not only detect both local and global bridge damage, but could also differentiate between damage types using only one mode shape. The proposed method was compared to a previously developed SHM method.

Structural damage identification using piezoelectric impedance measurement with sparse inverse analysis

Science.gov (United States)

Cao, Pei; Qi, Shuai; Tang, J.

2018-03-01

The impedance/admittance measurements of a piezoelectric transducer bonded to or embedded in a host structure can be used as damage indicator. When a credible model of the healthy structure, such as the finite element model, is available, using the impedance/admittance change information as input, it is possible to identify both the location and severity of damage. The inverse analysis, however, may be under-determined as the number of unknowns in high-frequency analysis is usually large while available input information is limited. The fundamental challenge thus is how to find a small set of solutions that cover the true damage scenario. In this research we cast the damage identification problem into a multi-objective optimization framework to tackle this challenge. With damage locations and severities as unknown variables, one of the objective functions is the difference between impedance-based model prediction in the parametric space and the actual measurements. Considering that damage occurrence generally affects only a small number of elements, we choose the sparsity of the unknown variables as another objective function, deliberately, the l 0 norm. Subsequently, a multi-objective Dividing RECTangles (DIRECT) algorithm is developed to facilitate the inverse analysis where the sparsity is further emphasized by sigmoid transformation. As a deterministic technique, this approach yields results that are repeatable and conclusive. In addition, only one algorithmic parameter, the number of function evaluations, is needed. Numerical and experimental case studies demonstrate that the proposed framework is capable of obtaining high-quality damage identification solutions with limited measurement information.

Seismic damage identification for steel structures using distributed fiber optics.

Science.gov (United States)

Hou, Shuang; Cai, C S; Ou, Jinping

2009-08-01

A distributed fiber optic monitoring methodology based on optic time domain reflectometry technology is developed for seismic damage identification of steel structures. Epoxy with a strength closely associated to a specified structure damage state is used for bonding zigzagged configured optic fibers on the surfaces of the structure. Sensing the local deformation of the structure, the epoxy modulates the signal change within the optic fiber in response to the damage state of the structure. A monotonic loading test is conducted on a steel specimen installed with the proposed sensing system using selected epoxy that will crack at the designated strain level, which indicates the damage of the steel structure. Then, using the selected epoxy, a varying degree of cyclic loading amplitudes, which is associated with different damage states, is applied on a second specimen. The test results show that the specimen's damage can be identified by the optic sensors, and its maximum local deformation can be recorded by the sensing system; moreover, the damage evolution can also be identified.

Identification of damage in composite structures using Gaussian mixture model-processed Lamb waves

Science.gov (United States)

Wang, Qiang; Ma, Shuxian; Yue, Dong

2018-04-01

Composite materials have comprehensively better properties than traditional materials, and therefore have been more and more widely used, especially because of its higher strength-weight ratio. However, the damage of composite structures is usually varied and complicated. In order to ensure the security of these structures, it is necessary to monitor and distinguish the structural damage in a timely manner. Lamb wave-based structural health monitoring (SHM) has been proved to be effective in online structural damage detection and evaluation; furthermore, the characteristic parameters of the multi-mode Lamb wave varies in response to different types of damage in the composite material. This paper studies the damage identification approach for composite structures using the Lamb wave and the Gaussian mixture model (GMM). The algorithm and principle of the GMM, and the parameter estimation, is introduced. Multi-statistical characteristic parameters of the excited Lamb waves are extracted, and the parameter space with reduced dimensions is adopted by principal component analysis (PCA). The damage identification system using the GMM is then established through training. Experiments on a glass fiber-reinforced epoxy composite laminate plate are conducted to verify the feasibility of the proposed approach in terms of damage classification. The experimental results show that different types of damage can be identified according to the value of the likelihood function of the GMM.

Structural damage identification in wind turbine blades using piezoelectric active sensing with ultrasonic validation

Energy Technology Data Exchange (ETDEWEB)

Claytor, Thomas N [Los Alamos National Laboratory; Ammerman, Curtt N [Los Alamos National Laboratory; Park, Gyu Hae [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Farrar, Charles R [Los Alamos National Laboratory; Atterbury, Marie K [Los Alamos National Laboratory

2010-01-01

This paper gives a brief overview of a new project at LANL in structural damage identification for wind turbines. This project makes use of modeling capabilities and sensing technology to understand realistic blade loading on large turbine blades, with the goal of developing the technology needed to automatically detect early damage. Several structural health monitoring (SHM) techniques using piezoelectric active materials are being investigated for the development of wireless, low power sensors that interrogate sections of the wind turbine blade using Lamb wave propagation data, frequency response functions (FRFs), and time-series analysis methods. The modeling and sensor research will be compared with extensive experimental testing, including wind tunnel experiments, load and fatigue tests, and ultrasonic scans - on small- to mid-scale turbine blades. Furthermore, this study will investigate the effect of local damage on the global response of the blade by monitoring low-frequency response changes.

A new surface fractal dimension for displacement mode shape-based damage identification of plate-type structures

Science.gov (United States)

Shi, Binkai; Qiao, Pizhong

2018-03-01

Vibration-based nondestructive testing is an area of growing interest and worthy of exploring new and innovative approaches. The displacement mode shape is often chosen to identify damage due to its local detailed characteristic and less sensitivity to surrounding noise. Requirement for baseline mode shape in most vibration-based damage identification limits application of such a strategy. In this study, a new surface fractal dimension called edge perimeter dimension (EPD) is formulated, from which an EPD-based window dimension locus (EPD-WDL) algorithm for irregularity or damage identification of plate-type structures is established. An analytical notch-type damage model of simply-supported plates is proposed to evaluate notch effect on plate vibration performance; while a sub-domain of notch cases with less effect is selected to investigate robustness of the proposed damage identification algorithm. Then, fundamental aspects of EPD-WDL algorithm in term of notch localization, notch quantification, and noise immunity are assessed. A mathematical solution called isomorphism is implemented to remove false peaks caused by inflexions of mode shapes when applying the EPD-WDL algorithm to higher mode shapes. The effectiveness and practicability of the EPD-WDL algorithm are demonstrated by an experimental procedure on damage identification of an artificially-induced notched aluminum cantilever plate using a measurement system of piezoelectric lead-zirconate (PZT) actuator and scanning laser Doppler vibrometer (SLDV). As demonstrated in both the analytical and experimental evaluations, the new surface fractal dimension technique developed is capable of effectively identifying damage in plate-type structures.

A flexibility-based method via the iterated improved reduction system and the cuckoo optimization algorithm for damage quantification with limited sensors

International Nuclear Information System (INIS)

Zare Hosseinzadeh, Ali; Ghodrati Amiri, Gholamreza; Bagheri, Abdollah; Koo, Ki-Young

2014-01-01

In this paper, a novel and effective damage diagnosis algorithm is proposed to localize and quantify structural damage using incomplete modal data, considering the existence of some limitations in the number of attached sensors on structures. The damage detection problem is formulated as an optimization problem by computing static displacements in the reduced model of a structure subjected to a unique static load. The static responses are computed through the flexibility matrix of the damaged structure obtained based on the incomplete modal data of the structure. In the algorithm, an iterated improved reduction system method is applied to prepare an accurate reduced model of a structure. The optimization problem is solved via a new evolutionary optimization algorithm called the cuckoo optimization algorithm. The efficiency and robustness of the presented method are demonstrated through three numerical examples. Moreover, the efficiency of the method is verified by an experimental study of a five-story shear building structure on a shaking table considering only two sensors. The obtained damage identification results for the numerical and experimental studies show the suitable and stable performance of the proposed damage identification method for structures with limited sensors. (paper)

Damage identification on spatial Timoshenko arches by means of genetic algorithms

Science.gov (United States)

Greco, A.; D'Urso, D.; Cannizzaro, F.; Pluchino, A.

2018-05-01

In this paper a procedure for the dynamic identification of damage in spatial Timoshenko arches is presented. The proposed approach is based on the calculation of an arbitrary number of exact eigen-properties of a damaged spatial arch by means of the Wittrick and Williams algorithm. The proposed damage model considers a reduction of the volume in a part of the arch, and is therefore suitable, differently than what is commonly proposed in the main part of the dedicated literature, not only for concentrated cracks but also for diffused damaged zones which may involve a loss of mass. Different damage scenarios can be taken into account with variable location, intensity and extension of the damage as well as number of damaged segments. An optimization procedure, aiming at identifying which damage configuration minimizes the difference between its eigen-properties and a set of measured modal quantities for the structure, is implemented making use of genetic algorithms. In this context, an initial random population of chromosomes, representing different damage distributions along the arch, is forced to evolve towards the fittest solution. Several applications with different, single or multiple, damaged zones and boundary conditions confirm the validity and the applicability of the proposed procedure even in presence of instrumental errors on the measured data.

Wavelet Transformation for Damage Identication in Wind Turbine Blades

DEFF Research Database (Denmark)

Ulriksen, Martin Dalgaard; Skov, Jonas falk; Kirkegaard, Poul Henning

2014-01-01

The present paper documents a proposed modal and wavelet analysis-based structural health monitoring (SHM) method for damage identification in wind turbine blades. A finite element (FE) model of a full-scale wind turbine blade is developed and introduced to a transverse surface crack. Hereby, post......-damage mode shapes are derived through modal analysis and subsequently analyzed with continuous two-dimensional wavelet transformation for damage identification, namely detection, localization and assessment. It is found that valid damage identification is obtained even when utilizing the mode shape...

Vibration-Based Damage Diagnosis in a Laboratory Cable-Stayed Bridge Model via an RCP-ARX Model Based Method

International Nuclear Information System (INIS)

Michaelides, P G; Apostolellis, P G; Fassois, S D

2011-01-01

Vibration-based damage detection and identification in a laboratory cable-stayed bridge model is addressed under inherent, environmental, and experimental uncertainties. The problem is challenging as conventional stochastic methods face difficulties due to uncertainty underestimation. A novel method is formulated based on identified Random Coefficient Pooled ARX (RCP-ARX) representations of the dynamics and statistical hypothesis testing. The method benefits from the ability of RCP models in properly capturing uncertainty. Its effectiveness is demonstrated via a high number of experiments under a variety of damage scenarios.

Vibration-Based Damage Diagnosis in a Laboratory Cable-Stayed Bridge Model via an RCP-ARX Model Based Method

Energy Technology Data Exchange (ETDEWEB)

Michaelides, P G; Apostolellis, P G; Fassois, S D, E-mail: mixail@mech.upatras.gr, E-mail: fassois@mech.upatras.gr [Laboratory for Stochastic Mechanical Systems and Automation (SMSA), Department of Mechanical and Aeronautical Engineering, University of Patras, GR 265 00 Patras (Greece)

2011-07-19

Vibration-based damage detection and identification in a laboratory cable-stayed bridge model is addressed under inherent, environmental, and experimental uncertainties. The problem is challenging as conventional stochastic methods face difficulties due to uncertainty underestimation. A novel method is formulated based on identified Random Coefficient Pooled ARX (RCP-ARX) representations of the dynamics and statistical hypothesis testing. The method benefits from the ability of RCP models in properly capturing uncertainty. Its effectiveness is demonstrated via a high number of experiments under a variety of damage scenarios.

Damage Identification of Trusses with Elastic Supports Using FEM and Genetic Algorithm

Directory of Open Access Journals (Sweden)

Nam-Il Kim

2013-01-01

Full Text Available The computationally efficient damage identification technique for truss structures with elastic supports is proposed based on the force method. To transform the truss with supports into the equivalent free-standing model without supports, the novel zero-length dummy members are employed. General equilibrium equations and kinematic relations, in which the reaction forces and the displacements at the elastic supports are taken into account, are clearly formulated. The compatibility equations, in terms of forces in which the flexibilities of elastic supports are considered, are explicitly presented using the singular value decomposition (SVD technique. Both member and reaction forces are simultaneously and directly obtained. Then, all nodal displacements including constrained nodes are back calculated from the member and reaction forces. Next, the microgenetic algorithm (MGA is used to properly identify the site and the extent of multiple damages in truss structures. In order to verify the superiority of the current study, the numerical solutions are presented for the planar and space truss models with and without elastic supports. The numerical results indicate that the computational effort required by this study is found to be significantly lower than that of the displacement method.

Modal Identification and Damage Detection on a Concrete Highway Bridge by Frequency Domain Decomposition

DEFF Research Database (Denmark)

Brincker, Rune; Andersen, P.; Zhang, L.

2002-01-01

As a part of a research project co-founded by the European Community, a series of 15 damage tests were performed on a prestressed concrete highway bridge in Switzerland. The ambient response of the bridge was recorded for each damage case. A dense array of instruments allowed the identification...

Modal Identification and Damage Detection on a Concrete Highway Bridge by Frequency Domain Decomposition

DEFF Research Database (Denmark)

Brincker, Rune; Andersen, Palle; Zhang, Lingmi

2007-01-01

As a part of a research project co-founded by the European Community, a series of 15 damage tests were performed on a prestressed concrete highway bridge in Switzerland. The ambient response of the bridge was recorded for each damage case. A dense array of instruments allowed the identification...

A comparison of damage detection methods applied to civil engineering structures

DEFF Research Database (Denmark)

Gres, Szymon; Andersen, Palle; Johansen, Rasmus Johan

2018-01-01

Facilitating detection of early-stage damage is crucial for in-time repairs and cost-optimized maintenance plans of civil engineering structures. Preferably, the damage detection is performed by use of output vibration data, hereby avoiding modal identification of the structure. Most of the work...

A comparison of damage detection methods applied to civil engineering structures

DEFF Research Database (Denmark)

Gres, Szymon; Andersen, Palle; Johansen, Rasmus Johan

2017-01-01

Facilitating detection of early-stage damage is crucial for in-time repairs and cost-optimized maintenance plans of civil engineering structures. Preferably, the damage detection is performed by use of output vibration data, hereby avoiding modal identification of the structure. Most of the work...

Application of EPR, thermoluminescence as well as DNA damage examination methods and sprout inhibition for identification of irradiated food

International Nuclear Information System (INIS)

Malec-Czechowska, K.; Stachowicz, W.; Dancewicz, A.M.; Szot, Z.

1998-01-01

Irradiation of food with doses up to 10 kGy of gamma, X-rays or electron beam is a relatively new technology improving hygienic quality of food, diminishing morbidity due to food pathogens and reducing losses during food storage. Application of this technology increases constantly in the world; more and more irradiated food appears on the market in various countries. In Europe it is agreed notion that detection of irradiated foods should be obligatory procedure included into administrative control system of foodstuffs. For this purpose the reliable methods are needed by which detection of irradiation fact will be possible. Such methods are not easy to be worked out because irradiation induces changes which are to small to be detected by methods commonly applied for food control. Working out the methods suitable for identification of irradiated food has been carried out in many countries in the world and during the last decade within several local and/or international programmes including the intercomparison of results obtained in different laboratories. In our institute such investigations began already in the 80-ties using EPR spectrometry and thermoluminescence measurements. Applications of these methods were approved in 1996 as European Community Standards. Other methods are still under investigation. They include the analyses of DNA damage in irradiated foodstuffs of animal or plant origin and measurements of germination effectiveness of irradiated grains and fruits. In this communication we present some results obtained upon application of forementioned methods to detection of different kinds of food irradiated with gamma rays or electron beam. (author)

Damage Detection Based on Cross-Term Extraction from Bilinear Time-Frequency Distributions

Directory of Open Access Journals (Sweden)

Ma Yuchao

2014-01-01

Full Text Available Abundant damage information is implicated in the bilinear time-frequency distribution of structural dynamic signals, which could provide effective support for structural damage identification. Signal time-frequency analysis methods are reviewed, and the characters of linear time-frequency distribution and bilinear time-frequency distribution typically represented by the Wigner-Ville distribution are compared. The existence of the cross-term and its application in structural damage detection are demonstrated. A method of extracting the dominant term is proposed, which combines the short-time Fourier spectrum and Wigner-Ville distribution; then two-dimensional time-frequency transformation matrix is constructed and the complete cross-term is extracted finally. The distribution character of which could be applied to the structural damage identification. Through theoretical analysis, model experiment and numerical simulation of the girder structure, the change rate of cross-term amplitude is validated to identify the damage location and degree. The effectiveness of the cross-term of bilinear time-frequency distribution for damage detection is confirmed and the analytical method of damage identification used in structural engineering is available.

Identification of Damaged Spot Welds in a Complicated Joined Structure

International Nuclear Information System (INIS)

Yunus, M A; Rani, M N Abdul; Ouyang, H; Deng, H; James, S

2011-01-01

In automotive engineering, spot welds on assembled structures such as Body in White (BiW) have a significant effect on the vehicles' dynamic characteristics. Understandably, imperfections in the spot welds will cause variations in the dynamic properties such as natural frequencies and mode shapes of the structure. In this paper, a complicated welded structure which is a simplified Natural Gas Vehicle (NGV) platform is investigated. The structure fabricated from thin metal sheets consists of ten components. They are jointed together by a number of scattered spot welds. NASTRAN Solution 200 based on sensitivity analysis is used to identify the most sensitive parameters to natural frequencies. The numerical model of the undamaged structure is initially updated in order to minimise the discrepancies between the measured and numerical data using NASTRAN optimisation code. The initial updated model serves as a benchmark for the subsequent structural damage identification. The numerical data of the benchmark model is then compared with the measured data obtained from the damaged structure. The same updating procedure is applied to the benchmark model in order to bring the numerical data as close as possible to the measured data of the damaged structure. The disparity in certain parameter values from the parameter values used in the benchmark model shows a fault or damage in the location of a particular joint, depending on the severity of this disparity. The challenge in this work is to localise damaged area and quantify the damage of the complicated structure with multiple spot welds in the presence of uncertainty in the location and material properties of the welds.

Identification of Damaged Spot Welds in a Complicated Joined Structure

Energy Technology Data Exchange (ETDEWEB)

Yunus, M A; Rani, M N Abdul; Ouyang, H; Deng, H; James, S, E-mail: h.ouyang@liverpool.ac.uk [Department of Engineering, Harrison Hughes Building, University of Liverpool, Brownlow Hill, Liverpool L69 3GH (United Kingdom)

2011-07-19

In automotive engineering, spot welds on assembled structures such as Body in White (BiW) have a significant effect on the vehicles' dynamic characteristics. Understandably, imperfections in the spot welds will cause variations in the dynamic properties such as natural frequencies and mode shapes of the structure. In this paper, a complicated welded structure which is a simplified Natural Gas Vehicle (NGV) platform is investigated. The structure fabricated from thin metal sheets consists of ten components. They are jointed together by a number of scattered spot welds. NASTRAN Solution 200 based on sensitivity analysis is used to identify the most sensitive parameters to natural frequencies. The numerical model of the undamaged structure is initially updated in order to minimise the discrepancies between the measured and numerical data using NASTRAN optimisation code. The initial updated model serves as a benchmark for the subsequent structural damage identification. The numerical data of the benchmark model is then compared with the measured data obtained from the damaged structure. The same updating procedure is applied to the benchmark model in order to bring the numerical data as close as possible to the measured data of the damaged structure. The disparity in certain parameter values from the parameter values used in the benchmark model shows a fault or damage in the location of a particular joint, depending on the severity of this disparity. The challenge in this work is to localise damaged area and quantify the damage of the complicated structure with multiple spot welds in the presence of uncertainty in the location and material properties of the welds.

Structural Damage Identification in Stiffened Plate Fatigue Specimens Using Piezoelectric Active Sensing

Science.gov (United States)

2011-09-01

isolated AO mode first arrival, recorded at PZT 2, is shown at 3 different fatigue levels. Figure 5. The area under the PSD curve, calculated twice...Structural Damage Identification in Stiffened Plate Fatigue Specimens Using Piezoelectric Active Sensing B. L. GRISSO, G. PARK, L. W. SALVINO...with several challenges including limited performance knowledge of the materials, aluminum sensitization, structural fatigue performance, and

An Efficient Vital Area Identification Method

International Nuclear Information System (INIS)

Jung, Woo Sik

2017-01-01

A new Vital Area Identification (VAI) method was developed in this study for minimizing the burden of VAI procedure. It was accomplished by performing simplification of sabotage event trees or Probabilistic Safety Assessment (PSA) event trees at the very first stage of VAI procedure. Target sets and prevention sets are calculated from the sabotage fault tree. The rooms in the shortest (most economical) prevention set are selected and protected as vital areas. All physical protection is emphasized to protect these vital areas. All rooms in the protected area, the sabotage of which could lead to core damage, should be incorporated into sabotage fault tree. So, sabotage fault tree development is a very difficult task that requires high engineering costs. IAEA published INFCIRC/225/Rev.5 in 2011 which includes principal international guidelines for the physical protection of nuclear material and nuclear installations. A new efficient VAI method was developed and demonstrated in this study. Since this method drastically reduces VAI problem size, it provides very quick and economical VAI procedure. A consistent and integrated VAI procedure had been developed by taking advantage of PSA results, and more efficient VAI method was further developed in this study by inserting PSA event tree simplification at the initial stage of VAI procedure.

Extraction of artificial boundary frequencies for damage identification

Energy Technology Data Exchange (ETDEWEB)

Mao Lei; Lu Yong, E-mail: yong.lu@ed.ac.uk [Institute for Infrastructure and Environment, Joint Research Institute for Civil and Environmental Engineering (ERP), School of Engineering, University of Edinburgh, The Kings Buildings, Edinburgh EH9 3JL (United Kingdom)

2011-07-19

This paper introduces some recent progress in a study which is aimed at incorporating the so-called artificial boundary condition (ABC) frequencies for damage identification. The ABC frequencies are those corresponding to the natural frequencies of the system with additional pin supports, but may be extracted from specially configured incomplete frequency response function matrix of the original structure without the need of physically imposing the additional supports. A particular focus of this paper is placed on the actual extraction of such frequencies from physical experiments and the associated data processing and analysis. Results will demonstrate that it is possible to extract the first few ABC frequencies for a variety of boundary conditions with 1-2 artificial pin supports in a beam or a slab structure.

Extraction of artificial boundary frequencies for damage identification

International Nuclear Information System (INIS)

Mao Lei; Lu Yong

2011-01-01

This paper introduces some recent progress in a study which is aimed at incorporating the so-called artificial boundary condition (ABC) frequencies for damage identification. The ABC frequencies are those corresponding to the natural frequencies of the system with additional pin supports, but may be extracted from specially configured incomplete frequency response function matrix of the original structure without the need of physically imposing the additional supports. A particular focus of this paper is placed on the actual extraction of such frequencies from physical experiments and the associated data processing and analysis. Results will demonstrate that it is possible to extract the first few ABC frequencies for a variety of boundary conditions with 1-2 artificial pin supports in a beam or a slab structure.

Spectral algorithm for non-destructive damage localisation: Application to an ancient masonry arch model

Science.gov (United States)

Masciotta, Maria-Giovanna; Ramos, Luís F.; Lourenço, Paulo B.; Vasta, Marcello

2017-02-01

Structural monitoring and vibration-based damage identification methods are fundamental tools for condition assessment and early-stage damage identification, especially when dealing with the conservation of historical constructions and the maintenance of strategic civil structures. However, although the substantial advances in the field, several issues must still be addressed to broaden the application range of such tools and to assert their reliability. This study deals with the experimental validation of a novel method for non-destructive damage identification purposes. This method is based on the use of spectral output signals and has been recently validated by the authors through a numerical simulation. After a brief insight into the basic principles of the proposed approach, the spectral-based technique is applied to identify the experimental damage induced on a masonry arch through statically increasing loading. Once the direct and cross spectral density functions of the nodal response processes are estimated, the system's output power spectrum matrix is built and decomposed in eigenvalues and eigenvectors. The present study points out how the extracted spectral eigenparameters contribute to the damage analysis allowing to detect the occurrence of damage and to locate the target points where the cracks appear during the experimental tests. The sensitivity of the spectral formulation to the level of noise in the modal data is investigated and discussed. As a final evaluation criterion, the results from the spectrum-driven method are compared with the ones obtained from existing non-model based damage identification methods.

Criterion of damage beginning: experimental identification for laminate composite

International Nuclear Information System (INIS)

Thiebaud, F.; Perreux, D.; Varchon, D.; Lebras, J.

1996-01-01

The aim of this study is to propose a criterion of damage beginning for laminate composite. The materials is a glass-epoxy laminate [+55 deg.,-55 deg.[ n performed by winding filament process. First of all a description of the damage is performed and allows to define a damage variable. Thanks to the potential of free energy, an associated variable is defined. The damage criterion is written by using this last one. The parameter of the criterion is identified using mechanical and acoustical methods. The result is compared and exhibit a good agreement. (authors). 13 refs., 5 figs

Method development of damage detection in asymmetric buildings

Science.gov (United States)

Wang, Yi; Thambiratnam, David P.; Chan, Tommy H. T.; Nguyen, Andy

2018-01-01

Aesthetics and functionality requirements have caused most buildings to be asymmetric in recent times. Such buildings exhibit complex vibration characteristics under dynamic loads as there is coupling between the lateral and torsional components of vibration, and are referred to as torsionally coupled buildings. These buildings require three dimensional modelling and analysis. In spite of much recent research and some successful applications of vibration based damage detection methods to civil structures in recent years, the applications to asymmetric buildings has been a challenging task for structural engineers. There has been relatively little research on detecting and locating damage specific to torsionally coupled asymmetric buildings. This paper aims to compare the difference in vibration behaviour between symmetric and asymmetric buildings and then use the vibration characteristics for predicting damage in them. The need for developing a special method to detect damage in asymmetric buildings thus becomes evident. Towards this end, this paper modifies the traditional modal strain energy based damage index by decomposing the mode shapes into their lateral and vertical components and to form component specific damage indices. The improved approach is then developed by combining the modified strain energy based damage indices with the modal flexibility method which was modified to suit three dimensional structures to form a new damage indicator. The procedure is illustrated through numerical studies conducted on three dimensional five-story symmetric and asymmetric frame structures with the same layout, after validating the modelling techniques through experimental testing of a laboratory scale asymmetric building model. Vibration parameters obtained from finite element analysis of the intact and damaged building models are then applied into the proposed algorithms for detecting and locating the single and multiple damages in these buildings. The results

A Tensor-Based Structural Damage Identification and Severity Assessment

Science.gov (United States)

Anaissi, Ali; Makki Alamdari, Mehrisadat; Rakotoarivelo, Thierry; Khoa, Nguyen Lu Dang

2018-01-01

Early damage detection is critical for a large set of global ageing infrastructure. Structural Health Monitoring systems provide a sensor-based quantitative and objective approach to continuously monitor these structures, as opposed to traditional engineering visual inspection. Analysing these sensed data is one of the major Structural Health Monitoring (SHM) challenges. This paper presents a novel algorithm to detect and assess damage in structures such as bridges. This method applies tensor analysis for data fusion and feature extraction, and further uses one-class support vector machine on this feature to detect anomalies, i.e., structural damage. To evaluate this approach, we collected acceleration data from a sensor-based SHM system, which we deployed on a real bridge and on a laboratory specimen. The results show that our tensor method outperforms a state-of-the-art approach using the wavelet energy spectrum of the measured data. In the specimen case, our approach succeeded in detecting 92.5% of induced damage cases, as opposed to 61.1% for the wavelet-based approach. While our method was applied to bridges, its algorithm and computation can be used on other structures or sensor-data analysis problems, which involve large series of correlated data from multiple sensors. PMID:29301314

[Identification of early irreversible damage area in a rat model of cerebral ischemia and reperfusion].

Science.gov (United States)

Liu, S; Guo, Y

2000-02-01

To observe the early neuron ischemic damage in focal cerebral ischemia/reperfusion with histostaining methods of argyrophil III (AG III), Toludine blue(TB), and H&E, and to make out the 'separating line' between the areas of reversible and irreversible early ischemic damage. Forty-two male Wistar rats were randomly divided into the following groups: pseudo-surgical, blank-control, O2R0(occluded for 2 hours and reperfused for 0 hour), O2R0.5, O2R2, O2R4, O2R24. There were 6 rats in each group. Rats in experimental groups were suffered focal cerebral ischemia/reperfusion through a nylon suture method. After a special processor for tissue manage, the brain were coronal sectioned and stained with H&E, TB, and AG III. The area where dark neurons dwell in (ischemic core) were calculated with image analysis system. The success rate of ischemic model for this experiment is 90%. After being stained with argyrophil III method, normal neurons appear yellow or pale brown, which is hardly distinguished from the pale brown background. The ischemic neuron stained black, and has collapsed body and "corkscrew-like" axon or dentries, which were broken to some extent. The neuropil in the dark neurons dwelt area appears gray or pale black, which is apparently different from the pale brown neighborhood area. The distribution of dark neurons in cortex varies according to different layers, and has a character of columnar form. The dark neurons present as early as 2 hours ischemia without reperfusion with AG III method. AG III stain could selectively display early ischemic neurons, the area dwelt by dark neurons represent early ischemic core. Dark neuron is possibly the irreversibly damaged neuron. Identification of dark neurons could be helpful in the discrimination between early ischemic center and penumbra.

Direct Index Method of Beam Damage Location Detection Based on Difference Theory of Strain Modal Shapes and the Genetic Algorithms Application

Directory of Open Access Journals (Sweden)

Bao Zhenming

2012-01-01

Full Text Available Structural damage identification is to determine the structure health status and analyze the test results. The three key problems to be solved are as follows: the existence of damage in structure, to detect the damage location, and to confirm the damage degree or damage form. Damage generally changes the structure physical properties (i.e., stiffness, mass, and damping corresponding with the modal characteristics of the structure (i.e., natural frequencies, modal shapes, and modal damping. The research results show that strain mode can be more sensitive and effective for local damage. The direct index method of damage location detection is based on difference theory, without the modal parameter of the original structure. FEM numerical simulation to partial crack with different degree is done. The criteria of damage location detection can be obtained by strain mode difference curve through cubic spline interpolation. Also the genetic algorithm box in Matlab is used. It has been possible to identify the damage to a reasonable level of accuracy.

Damage Detection in Bridge Structure Using Vibration Data under Random Travelling Vehicle Loads

International Nuclear Information System (INIS)

Loh, C H; Hung, T Y; Chen, S F; Hsu, W T

2015-01-01

Due to the random nature of the road excitation and the inherent uncertainties in bridge-vehicle system, damage identification of bridge structure through continuous monitoring under operating situation become a challenge problem. Methods for system identification and damage detection of a continuous two-span concrete bridge structure in time domain is presented using interaction forces from random moving vehicles as excitation. The signals recorded in different locations of the instrumented bridge are mixed with signals from different internal and external (road roughness) vibration sources. The damage structure is also modelled as the stiffness reduction in one of the beam element. For the purpose of system identification and damage detection three different output-only modal analysis techniques are proposed: The covariance-driven stochastic subspace identification (SSI-COV), the blind source separation algorithms (called Second Order Blind Identification) and the multivariate AR model. The advantages and disadvantages of the three algorithms are discussed. Finally, the null-space damage index, subspace damage indices and mode shape slope change are used to detect and locate the damage. The proposed approaches has been tested in simulation and proved to be effective for structural health monitoring. (paper)

Hob Identification Methods

Directory of Open Access Journals (Sweden)

Andrzej Piotrowski

2018-03-01

Full Text Available In industrial practice, hobs are manufactured and used. The problem boils down to the identification of a hob with defining its profile, which depends on many design and technological parameters (such as the grinding wheel size, profile, type and positioning during machining. This makes the basis for the correct execution and sharpening of the tool. The accuracy of the hob determines the quality of gear wheel teeth being shaped. The article presents the hob identification methods that are possible to be used in industrial and laboratory practice.

An Improved Method of Parameter Identification and Damage Detection in Beam Structures under Flexural Vibration Using Wavelet Multi-Resolution Analysis

Directory of Open Access Journals (Sweden)

Seyed Alireza Ravanfar

2015-09-01

Full Text Available This paper reports on a two-step approach for optimally determining the location and severity of damage in beam structures under flexural vibration. The first step focuses on damage location detection. This is done by defining the damage index called relative wavelet packet entropy (RWPE. The damage severities of the model in terms of loss of stiffness are assessed in the second step using the inverse solution of equations of motion of a structural system in the wavelet domain. For this purpose, the connection coefficient of the scaling function to convert the equations of motion in the time domain into the wavelet domain is applied. Subsequently, the dominant components based on the relative energies of the wavelet packet transform (WPT components of the acceleration responses are defined. To obtain the best estimation of the stiffness parameters of the model, the least squares error minimization is used iteratively over the dominant components. Then, the severity of the damage is evaluated by comparing the stiffness parameters of the identified model before and after the occurrence of damage. The numerical and experimental results demonstrate that the proposed method is robust and effective for the determination of damage location and accurate estimation of the loss in stiffness due to damage.

Health condition identification of multi-stage planetary gearboxes using a mRVM-based method

Science.gov (United States)

Lei, Yaguo; Liu, Zongyao; Wu, Xionghui; Li, Naipeng; Chen, Wu; Lin, Jing

2015-08-01

Multi-stage planetary gearboxes are widely applied in aerospace, automotive and heavy industries. Their key components, such as gears and bearings, can easily suffer from damage due to tough working environment. Health condition identification of planetary gearboxes aims to prevent accidents and save costs. This paper proposes a method based on multiclass relevance vector machine (mRVM) to identify health condition of multi-stage planetary gearboxes. In this method, a mRVM algorithm is adopted as a classifier, and two features, i.e. accumulative amplitudes of carrier orders (AACO) and energy ratio based on difference spectra (ERDS), are used as the input of the classifier to classify different health conditions of multi-stage planetary gearboxes. To test the proposed method, seven health conditions of a two-stage planetary gearbox are considered and vibration data is acquired from the planetary gearbox under different motor speeds and loading conditions. The results of three tests based on different data show that the proposed method obtains an improved identification performance and robustness compared with the existing method.

A comparative assessment of different frequency based damage detection in unidirectional composite plates using MFC sensors

Science.gov (United States)

de Medeiros, Ricardo; Sartorato, Murilo; Vandepitte, Dirk; Tita, Volnei

2016-11-01

The basic concept of the vibration based damage identification methods is that the dynamic behaviour of a structure can change if damage occurs. Damage in a structure can alter the structural integrity, and therefore, the physical properties like stiffness, mass and/or damping may change. The dynamic behaviour of a structure is a function of these physical properties and will, therefore, directly be affected by the damage. The dynamic behaviour can be described in terms of time, frequency and modal domain parameters. The changes in these parameters (or properties derived from these parameters) are used as indicators of damage. Hence, this work has two main objectives. The first one is to provide an overview of the structural vibration based damage identification methods. For this purpose, a fundamental description of the structural vibration based damage identification problem is given, followed by a short literature overview of the damage features, which are commonly addressed. The second objective is to create a damage identification method for detection of the damage in composite structures. To aid in this process, two basic principles are discussed, namely the effect of the potential damage case on the dynamic behaviour, and the consequences involved with the information reduction in the signal processing. Modal properties from the structural dynamic output response are obtained. In addition, experimental and computational results are presented for the application of modal analysis techniques applied to composite specimens with and without damage. The excitation of the structures is performed using an impact hammer and, for measuring the output data, accelerometers as well as piezoelectric sensors. Finite element models are developed by shell elements, and numerical results are compared to experimental data, showing good correlation for the response of the specimens in some specific frequency range. Finally, FRFs are analysed using suitable metrics, including a

Roller Bearing Monitoring by New Subspace-Based Damage Indicator

Directory of Open Access Journals (Sweden)

G. Gautier

2015-01-01

Full Text Available A frequency-band subspace-based damage identification method for fault diagnosis in roller bearings is presented. Subspace-based damage indicators are obtained by filtering the vibration data in the frequency range where damage is likely to occur, that is, around the bearing characteristic frequencies. The proposed method is validated by considering simulated data of a damaged bearing. Also, an experimental case is considered which focuses on collecting the vibration data issued from a run-to-failure test. It is shown that the proposed method can detect bearing defects and, as such, it appears to be an efficient tool for diagnosis purpose.

Identification methods for structural health monitoring

CERN Document Server

Papadimitriou, Costas

2016-01-01

The papers in this volume provide an introduction to well known and established system identification methods for structural health monitoring and to more advanced, state-of-the-art tools, able to tackle the challenges associated with actual implementation. Starting with an overview on fundamental methods, introductory concepts are provided on the general framework of time and frequency domain, parametric and non-parametric methods, input-output or output only techniques. Cutting edge tools are introduced including, nonlinear system identification methods; Bayesian tools; and advanced modal identification techniques (such as the Kalman and particle filters, the fast Bayesian FFT method). Advanced computational tools for uncertainty quantification are discussed to provide a link between monitoring and structural integrity assessment. In addition, full scale applications and field deployments that illustrate the workings and effectiveness of the introduced monitoring schemes are demonstrated.

Experimental damage analysis of steels after exploitation loading

Directory of Open Access Journals (Sweden)

B. Augustyniak

2010-06-01

Full Text Available Development of creep damage at elevated temperatures and structural degradation due to plastic deformation at room temperature were assessed using destructive and non-destructive methods in steels commonly applied in power plants (40HNMA, 13HMF and P91. As destructive methods the standard tension tests were carried out after every kind of prestraining. Subsequently, an evolution of the selected tension parameters was taken into account for damage identification. In order to assess a damage development during the creep and plastic deformation the tests for the steels were interrupted for a range of the selected strain magnitudes. The ultrasonic and magnetic techniques were used as the non-destructive methods for damage evaluation. The experimental programme also contained microscopic observations.

Musical Tone Law Method for the Structural Damage Detection

Directory of Open Access Journals (Sweden)

Weisong Yang

2017-01-01

Full Text Available Damage detection tests of inclined cables, steel pipes, spherical shells, and an actual cable-stayed bridge were conducted based on the proposed musical tone law method. The results show that the musical tone law method could be used in the damage detection of isotropic material structures with simple shape, like cables, pipes, plates, and shells. Having distinct spectral lines like a comb with a certain interval distribution rule is the main characteristic of the music tone law. Damage detection baseline could be established by quantizing the fitting relationship between modal orders and the corresponding frequency values. The main advantage of this method is that it could be used in the structural damage detection without vibration information of an intact structure as a reference.

Applications of meshless methods for damage computations with finite strains

International Nuclear Information System (INIS)

Pan Xiaofei; Yuan Huang

2009-01-01

Material defects such as cavities have great effects on the damage process in ductile materials. Computations based on finite element methods (FEMs) often suffer from instability due to material failure as well as large distortions. To improve computational efficiency and robustness the element-free Galerkin (EFG) method is applied in the micro-mechanical constitute damage model proposed by Gurson and modified by Tvergaard and Needleman (the GTN damage model). The EFG algorithm is implemented in the general purpose finite element code ABAQUS via the user interface UEL. With the help of the EFG method, damage processes in uniaxial tension specimens and notched specimens are analyzed and verified with experimental data. Computational results reveal that the damage which takes place in the interior of specimens will extend to the exterior and cause fracture of specimens; the damage is a fast procedure relative to the whole tensing process. The EFG method provides more stable and robust numerical solution in comparing with the FEM analysis

Analysis Of Damage Arising From Exploitation Of The Aircraft

Directory of Open Access Journals (Sweden)

Woźny Piotr

2014-12-01

Full Text Available During exploitation, due to a variety of reasons, aircrafts are damaged or suffer from different failures. In the process of operation, using appropriate methods of diagnosis, failure, damage, and relative deregulation of individual elements or units can be detected. For this purpose, one can apply a number of indirect diagnostic methods with the use of recorded diagnostic signals or a direct diagnosis with the use of non-destructive methods. The proper identification of the technical condition allows to determine the causes of irregularities and take actions aimed at preventing their occurrence. The article presents the types of exploitation damage of a multi-purpose aircraft. In addition, the criteria for the division of damage and research methods of the causes of damage are presented. Furthermore, an analysis of the scope of activities to be performed during the research of causes of damage to the aircraft is made.

Experimental validation of a structural damage detection method based on marginal Hilbert spectrum

Science.gov (United States)

Banerji, Srishti; Roy, Timir B.; Sabamehr, Ardalan; Bagchi, Ashutosh

2017-04-01

Structural Health Monitoring (SHM) using dynamic characteristics of structures is crucial for early damage detection. Damage detection can be performed by capturing and assessing structural responses. Instrumented structures are monitored by analyzing the responses recorded by deployed sensors in the form of signals. Signal processing is an important tool for the processing of the collected data to diagnose anomalies in structural behavior. The vibration signature of the structure varies with damage. In order to attain effective damage detection, preservation of non-linear and non-stationary features of real structural responses is important. Decomposition of the signals into Intrinsic Mode Functions (IMF) by Empirical Mode Decomposition (EMD) and application of Hilbert-Huang Transform (HHT) addresses the time-varying instantaneous properties of the structural response. The energy distribution among different vibration modes of the intact and damaged structure depicted by Marginal Hilbert Spectrum (MHS) detects location and severity of the damage. The present work investigates damage detection analytically and experimentally by employing MHS. The testing of this methodology for different damage scenarios of a frame structure resulted in its accurate damage identification. The sensitivity of Hilbert Spectral Analysis (HSA) is assessed with varying frequencies and damage locations by means of calculating Damage Indices (DI) from the Hilbert spectrum curves of the undamaged and damaged structures.

Method to reduce damage to backing plate

Science.gov (United States)

Perry, Michael D.; Banks, Paul S.; Stuart, Brent C.

2001-01-01

The present invention is a method for penetrating a workpiece using an ultra-short pulse laser beam without causing damage to subsequent surfaces facing the laser. Several embodiments are shown which place holes in fuel injectors without damaging the back surface of the sack in which the fuel is ejected. In one embodiment, pulses from an ultra short pulse laser remove about 10 nm to 1000 nm of material per pulse. In one embodiment, a plasma source is attached to the fuel injector and initiated by common methods such as microwave energy. In another embodiment of the invention, the sack void is filled with a solid. In one other embodiment, a high viscosity liquid is placed within the sack. In general, high-viscosity liquids preferably used in this invention should have a high damage threshold and have a diffusing property.

Optimal sampling in damage detection of flexural beams by continuous wavelet transform

International Nuclear Information System (INIS)

Basu, B; Broderick, B M; Montanari, L; Spagnoli, A

2015-01-01

Modern measurement techniques are improving in capability to capture spatial displacement fields occurring in deformed structures with high precision and in a quasi-continuous manner. This in turn has made the use of vibration-based damage identification methods more effective and reliable for real applications. However, practical measurement and data processing issues still present barriers to the application of these methods in identifying several types of structural damage. This paper deals with spatial Continuous Wavelet Transform (CWT) damage identification methods in beam structures with the aim of addressing the following key questions: (i) can the cost of damage detection be reduced by down-sampling? (ii) what is the minimum number of sampling intervals required for optimal damage detection ? The first three free vibration modes of a cantilever and a simple supported beam with an edge open crack are numerically simulated. A thorough parametric study is carried out by taking into account the key parameters governing the problem, including level of noise, crack depth and location, mechanical and geometrical parameters of the beam. The results are employed to assess the optimal number of sampling intervals for effective damage detection. (paper)

Identification of sewage leaks by active remote-sensing methods

Science.gov (United States)

Goldshleger, Naftaly; Basson, Uri

2016-04-01

The increasing length of sewage pipelines, and concomitant risk of leaks due to urban and industrial growth and development is exposing the surrounding land to contamination risk and environmental harm. It is therefore important to locate such leaks in a timely manner, to minimize the damage. Advances in active remote sensing Ground Penetrating Radar (GPR) and Frequency Domain Electromagnetic (FDEM) technologies was used to identify leaking potentially responsible for pollution and to identify minor spills before they cause widespread damage. This study focused on the development of these electromagnetic methods to replace conventional acoustic methods for the identification of leaks along sewage pipes. Electromagnetic methods provide an additional advantage in that they allow mapping of the fluid-transport system in the subsurface. Leak-detection systems using GPR and FDEM are not limited to large amounts of water, but enable detecting leaks of tens of liters per hour, because they can locate increases in environmental moisture content of only a few percentage along the pipes. The importance and uniqueness of this research lies in the development of practical tools to provide a snapshot and monitoring of the spatial changes in soil moisture content up to depths of about 3-4 m, in open and paved areas, at relatively low cost, in real time or close to real time. Spatial measurements performed using GPR and FDEM systems allow monitoring many tens of thousands of measurement points per hectare, thus providing a picture of the spatial situation along pipelines and the surrounding. The main purpose of this study was to develop a method for detecting sewage leaks using the above-proposed geophysical methods, since their contaminants can severely affect public health. We focused on identifying, locating and characterizing such leaks in sewage pipes in residential and industrial areas.

Identification of Fusarium damaged wheat kernels using image analysis

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Ondřej Jirsa

2011-01-01

Full Text Available Visual evaluation of kernels damaged by Fusarium spp. pathogens is labour intensive and due to a subjective approach, it can lead to inconsistencies. Digital imaging technology combined with appropriate statistical methods can provide much faster and more accurate evaluation of the visually scabby kernels proportion. The aim of the present study was to develop a discrimination model to identify wheat kernels infected by Fusarium spp. using digital image analysis and statistical methods. Winter wheat kernels from field experiments were evaluated visually as healthy or damaged. Deoxynivalenol (DON content was determined in individual kernels using an ELISA method. Images of individual kernels were produced using a digital camera on dark background. Colour and shape descriptors were obtained by image analysis from the area representing the kernel. Healthy and damaged kernels differed significantly in DON content and kernel weight. Various combinations of individual shape and colour descriptors were examined during the development of the model using linear discriminant analysis. In addition to basic descriptors of the RGB colour model (red, green, blue, very good classification was also obtained using hue from the HSL colour model (hue, saturation, luminance. The accuracy of classification using the developed discrimination model based on RGBH descriptors was 85 %. The shape descriptors themselves were not specific enough to distinguish individual kernels.

[A accurate identification method for Chinese materia medica--systematic identification of Chinese materia medica].

Science.gov (United States)

Wang, Xue-Yong; Liao, Cai-Li; Liu, Si-Qi; Liu, Chun-Sheng; Shao, Ai-Juan; Huang, Lu-Qi

2013-05-01

This paper put forward a more accurate identification method for identification of Chinese materia medica (CMM), the systematic identification of Chinese materia medica (SICMM) , which might solve difficulties in CMM identification used the ordinary traditional ways. Concepts, mechanisms and methods of SICMM were systematically introduced and possibility was proved by experiments. The establishment of SICMM will solve problems in identification of Chinese materia medica not only in phenotypic characters like the mnorphous, microstructure, chemical constituents, but also further discovery evolution and classification of species, subspecies and population in medical plants. The establishment of SICMM will improve the development of identification of CMM and create a more extensive study space.

Star identification methods, techniques and algorithms

CERN Document Server

Zhang, Guangjun

2017-01-01

This book summarizes the research advances in star identification that the author’s team has made over the past 10 years, systematically introducing the principles of star identification, general methods, key techniques and practicable algorithms. It also offers examples of hardware implementation and performance evaluation for the star identification algorithms. Star identification is the key step for celestial navigation and greatly improves the performance of star sensors, and as such the book include the fundamentals of star sensors and celestial navigation, the processing of the star catalog and star images, star identification using modified triangle algorithms, star identification using star patterns and using neural networks, rapid star tracking using star matching between adjacent frames, as well as implementation hardware and using performance tests for star identification. It is not only valuable as a reference book for star sensor designers and researchers working in pattern recognition and othe...

Quantification and identification of lightning damage in tropical forests.

Science.gov (United States)

Yanoviak, Stephen P; Gora, Evan M; Burchfield, Jeffrey M; Bitzer, Phillip M; Detto, Matteo

2017-07-01

Accurate estimates of tree mortality are essential for the development of mechanistic forest dynamics models, and for estimating carbon storage and cycling. However, identifying agents of tree mortality is difficult and imprecise. Although lightning kills thousands of trees each year and is an important agent of mortality in some forests, the frequency and distribution of lightning-caused tree death remain unknown for most forests. Moreover, because all evidence regarding the effects of lightning on trees is necessarily anecdotal and post hoc, rigorous tests of hypotheses regarding the ecological effects of lightning are impossible. We developed a combined electronic sensor/camera-based system for the location and characterization of lightning strikes to the forest canopy in near real time and tested the system in the forest of Barro Colorado Island, Panama. Cameras mounted on towers provided continuous video recordings of the forest canopy that were analyzed to determine the locations of lightning strikes. We used a preliminary version of this system to record and locate 18 lightning strikes to the forest over a 3-year period. Data from field surveys of known lightning strike locations (obtained from the camera system) enabled us to develop a protocol for reliable, ground-based identification of suspected lightning damage to tropical trees. In all cases, lightning damage was relatively inconspicuous; it would have been overlooked by ground-based observers having no knowledge of the event. We identified three types of evidence that can be used to consistently identify lightning strike damage in tropical forests: (1) localized and directionally biased branch mortality associated with flashover among tree and sapling crowns, (2) mortality of lianas or saplings near lianas, and (3) scorched or wilting epiphytic and hemiepiphytic plants. The longitudinal trunk scars that are typical of lightning-damaged temperate trees were never observed in this study. Given the

Dynamic Method of Neutral Axis Position Determination and Damage Identification with Distributed Long-Gauge FBG Sensors.

Science.gov (United States)

Tang, Yongsheng; Ren, Zhongdao

2017-02-20

The neutral axis position (NAP) is a key parameter of a flexural member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS). In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG) sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC) is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC) beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of flexural structures can be facilitated.

Dynamic Method of Neutral Axis Position Determination and Damage Identification with Distributed Long-Gauge FBG Sensors

Directory of Open Access Journals (Sweden)

Yongsheng Tang

2017-02-01

Full Text Available The neutral axis position (NAP is a key parameter of a flexural member for structure design and safety evaluation. The accuracy of NAP measurement based on traditional methods does not satisfy the demands of structural performance assessment especially under live traffic loads. In this paper, a new method to determine NAP is developed by using modal macro-strain (MMS. In the proposed method, macro-strain is first measured with long-gauge Fiber Bragg Grating (FBG sensors; then the MMS is generated from the measured macro-strain with Fourier transform; and finally the neutral axis position coefficient (NAPC is determined from the MMS and the neutral axis depth is calculated with NAPC. To verify the effectiveness of the proposed method, some experiments on FE models, steel beam and reinforced concrete (RC beam were conducted. From the results, the plane section was first verified with MMS of the first bending mode. Then the results confirmed the high accuracy and stability for assessing NAP. The results also proved that the NAPC was a good indicator of local damage. In summary, with the proposed method, accurate assessment of flexural structures can be facilitated.

Damage detection in composite materials using Lamb wave methods

Science.gov (United States)

Kessler, Seth S.; Spearing, S. Mark; Soutis, Constantinos

2002-04-01

Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasi-isotropic graphite/epoxy test specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Linear wave scans were performed on narrow laminated specimens and sandwich beams with various cores by monitoring the transmitted waves with piezoceramic sensors. Optimal actuator and sensor configurations were devised through experimentation, and various types of driving signal were explored. These experiments provided a procedure capable of easily and accurately determining the time of flight of a Lamb wave pulse between an actuator and sensor. Lamb wave techniques provide more information about damage presence and severity than previously tested methods (frequency response techniques), and provide the possibility of determining damage location due to their local response nature. These methods may prove suitable for structural health monitoring applications since they travel long distances and can be applied with conformable piezoelectric actuators and sensors that require little power.

Repair methods for damaged pipeline beyond diving depth

OpenAIRE

Mohammadi, Keramat

2011-01-01

Master's thesis in Offshore Technology Mechanical damage of a subsea pipeline is found as one of the most severe concern in management of pipeline integrity. The need to reach and bring the hydrocarbons from the fields located in deep and ultra-deep waters, imposes the need to improve the technologies and techniques in order to repair any unacceptable damage in pipeline. The main objective of this work is to investigate various methods for repairing a subsea pipeline that has been damaged ...

Combination of Three Methods of Photo Voltaic Panels Damage Evaluation

Directory of Open Access Journals (Sweden)

Olšan T.

2017-06-01

Full Text Available In broken photovoltaic (PV cells the flow of electric current can be reduced in some places, which results in a lowered efficiency. In the present study, the damage of PV cells and panels was evaluated using three methods - electroluminescence, infrared camera imaging, and visual examination. The damage is detectable by all these methods which were presented and compared from the viewpoint of resolution, difficulty, and accuracy of monitoring the PV panels damage.

Lorestan Bronze Plate Design Identification by Nondestructive Radiography Method and Image Processing by Means of Histogram Matching

International Nuclear Information System (INIS)

Yahaghi, E.; Movafeghi, A.; Ahmadi, S.; Rokrok, B.; Mohammadzadeh, N.; Rastkhah, N.

2013-01-01

Radiography is known as one of the oldest and most widely used nondestructive testing techniques, where it introduces the most appreciated technique by producing images which are acting as unique fingerprint records of samples of interest. Among the interesting applications of radiography are archaeological and art applications. In this research, radiography was implemented for identification of a damaged art-historical material. The sample was a brass plate belonging to Iran cultural heritage. The estimated age of the plate was about 3500 years. The plate was discovered in Lorestan province, where it is generally called L orestan bronze . The plate was damaged seriously due to serious corrosion environmental attacks, and recognition of the sample was considered as the major problem. The simple radiography method was quite helpful for the plate determination but the method suffered from some major drawbacks due to contrast and thickness measurements. The thickness measurement and corrosion/erosion evaluation were the vital components of the inspection. The image processing techniques and precise thickness measurement method were added to the digitized radiographs. For the digital image processing, a histogram matching algorithm and an edge detection method were used. After all, the resulted image showed an enhanced quality image of the original traces of the hammered design. The results showed that a good experimental setup of radiography along with the image processing technique can give a high quality radiographic image which is able to be used effectively for the identification of art antiques. The human evaluation results also confirmed the ability of the proposed method with a high degree of certainty.

Fuel number identification method and device

International Nuclear Information System (INIS)

Doi, Takami; Seno, Makoto; Kikuchi, Takashi; Sakamoto, Hiromi; Takahashi, Masaki; Tanaka, Keiji.

1997-01-01

The present invention provides a method of and a device for automatically identifying fuel numbers impressed on fuel assemblies disposed in a fuel reprocessing facility, power plant and a reactor core at a high speed and at a high identification rate. Namely, three or more character images are photographed for one fuel assembly as an object of the identification under different illumination conditions. As a result, different character images by the number of the illumination directions can be obtained for identical impressed characters. Learning on a neural network system is applied to the images of all of the characters impressed on the fuel assembly obtained under illumination of predetermined directions. Then, result of the identification by the number of the illumination directions can be obtained for each of the characters as an object of the identification. As a result, since the result of the identification is determined based on a theory of decision of majority, highly automatic identification can be realized. (I.S.)

Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture

Science.gov (United States)

Steele, Kerry D [Kennewick, WA; Anderson, Gordon A [Benton City, WA; Gilbert, Ronald W [Morgan Hill, CA

2011-02-01

Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture are described. In one aspect, a communications device identification method includes providing identification information regarding a group of wireless identification devices within a wireless communications range of a reader, using the provided identification information, selecting one of a plurality of different search procedures for identifying unidentified ones of the wireless identification devices within the wireless communications range, and identifying at least some of the unidentified ones of the wireless identification devices using the selected one of the search procedures.

Multiple independent identification decisions: a method of calibrating eyewitness identifications.

Science.gov (United States)

Pryke, Sean; Lindsay, R C L; Dysart, Jennifer E; Dupuis, Paul

2004-02-01

Two experiments (N = 147 and N = 90) explored the use of multiple independent lineups to identify a target seen live. In Experiment 1, simultaneous face, body, and sequential voice lineups were used. In Experiment 2, sequential face, body, voice, and clothing lineups were used. Both studies demonstrated that multiple identifications (by the same witness) from independent lineups of different features are highly diagnostic of suspect guilt (G. L. Wells & R. C. L. Lindsay, 1980). The number of suspect and foil selections from multiple independent lineups provides a powerful method of calibrating the accuracy of eyewitness identification. Implications for use of current methods are discussed. ((c) 2004 APA, all rights reserved)

Use of simplified methods for predicting natural resource damages

International Nuclear Information System (INIS)

Loreti, C.P.; Boehm, P.D.; Gundlach, E.R.; Healy, E.A.; Rosenstein, A.B.; Tsomides, H.J.; Turton, D.J.; Webber, H.M.

1995-01-01

To reduce transaction costs and save time, the US Department of the Interior (DOI) and the National Oceanic and Atmospheric Administration (NOAA) have developed simplified methods for assessing natural resource damages from oil and chemical spills. DOI has proposed the use of two computer models, the Natural Resource Damage Assessment Model for Great Lakes Environments (NRDAM/GLE) and a revised Natural Resource Damage Assessment Model for Coastal and Marine Environments (NRDAM/CME) for predicting monetary damages for spills of oils and chemicals into the Great Lakes and coastal and marine environments. NOAA has used versions of these models to create Compensation Formulas, which it has proposed for calculating natural resource damages for oil spills of up to 50,000 gallons anywhere in the US. Based on a review of the documentation supporting the methods, the results of hundreds of sample runs of DOI's models, and the outputs of the thousands of model runs used to create NOAA's Compensation Formulas, this presentation discusses the ability of these simplified assessment procedures to make realistic damage estimates. The limitations of these procedures are described, and the need for validating the assumptions used in predicting natural resource injuries is discussed

Repair of damaged supraglottic airway devices: A novel method

Directory of Open Access Journals (Sweden)

Kapoor Dheeraj

2010-06-01

Full Text Available Abstract Damage of laryngeal mask airway and other supraglottic airway devices has always been a matter of concern. Although manufacturer recommends maximum 40 uses of LMA (and its congeners but damage before 40 uses needs to be evaluated. We hereby, describe a novel method of repair of supraglottic devices when damage occurs at mask inflation line or pilot balloon valve assembly.

Damage identification in beams by a response surface based technique

Directory of Open Access Journals (Sweden)

Teidj S.

2014-01-01

Full Text Available In this work, identification of damage in uniform homogeneous metallic beams was considered through the propagation of non dispersive elastic torsional waves. The proposed damage detection procedure consisted of the following sequence. Giving a localized torque excitation, having the form of a short half-sine pulse, the first step was calculating the transient solution of the resulting torsional wave. This torque could be generated in practice by means of asymmetric laser irradiation of the beam surface. Then, a localized defect assumed to be characterized by an abrupt reduction of beam section area with a given height and extent was placed at a known location of the beam. Next, the response in terms of transverse section rotation rate was obtained for a point situated afterwards the defect, where the sensor was positioned. This last could utilize in practice the concept of laser vibrometry. A parametric study has been conducted after that by using a full factorial design of experiments table and numerical simulations based on a finite difference characteristic scheme. This has enabled the derivation of a response surface model that was shown to represent adequately the response of the system in terms of the following factors: defect extent and severity. The final step was performing the inverse problem solution in order to identify the defect characteristics by using measurement.

Damage Identification of Wind Turbine Blades Using Piezoelectric Transducers

Directory of Open Access Journals (Sweden)

Seong-Won Choi

2014-01-01

Full Text Available This paper presents the experimental results of active-sensing structural health monitoring (SHM techniques, which utilize piezoelectric transducers as sensors and actuators, for determining the structural integrity of wind turbine blades. Specifically, Lamb wave propagations and frequency response functions at high frequency ranges are used to estimate the condition of wind turbine blades. For experiments, a 1 m section of a CX-100 blade is used. The goal of this study is to assess and compare the performance of each method in identifying incipient damage with a consideration given to field deployability. Overall, these methods yielded a sufficient damage detection capability to warrant further investigation. This paper also summarizes the SHM results of a full-scale fatigue test of a 9 m CX-100 blade using piezoelectric active sensors. This paper outlines considerations needed to design such SHM systems, experimental procedures and results, and additional issues that can be used as guidelines for future investigations.

Distributed Piezoelectric Sensor System for Damage Identification in Structures Subjected to Temperature Changes

Directory of Open Access Journals (Sweden)

Jaime Vitola

2017-05-01

Full Text Available Structural health monitoring (SHM is a very important area in a wide spectrum of fields and engineering applications. With an SHM system, it is possible to reduce the number of non-necessary inspection tasks, the associated risk and the maintenance cost in a wide range of structures during their lifetime. One of the problems in the detection and classification of damage are the constant changes in the operational and environmental conditions. Small changes of these conditions can be considered by the SHM system as damage even though the structure is healthy. Several applications for monitoring of structures have been developed and reported in the literature, and some of them include temperature compensation techniques. In real applications, however, digital processing technologies have proven their value by: (i offering a very interesting way to acquire information from the structures under test; (ii applying methodologies to provide a robust analysis; and (iii performing a damage identification with a practical useful accuracy. This work shows the implementation of an SHM system based on the use of piezoelectric (PZT sensors for inspecting a structure subjected to temperature changes. The methodology includes the use of multivariate analysis, sensor data fusion and machine learning approaches. The methodology is tested and evaluated with aluminum and composite structures that are subjected to temperature variations. Results show that damage can be detected and classified in all of the cases in spite of the temperature changes.

Distributed Piezoelectric Sensor System for Damage Identification in Structures Subjected to Temperature Changes.

Science.gov (United States)

Vitola, Jaime; Pozo, Francesc; Tibaduiza, Diego A; Anaya, Maribel

2017-05-31

Structural health monitoring (SHM) is a very important area in a wide spectrum of fields and engineering applications. With an SHM system, it is possible to reduce the number of non-necessary inspection tasks, the associated risk and the maintenance cost in a wide range of structures during their lifetime. One of the problems in the detection and classification of damage are the constant changes in the operational and environmental conditions. Small changes of these conditions can be considered by the SHM system as damage even though the structure is healthy. Several applications for monitoring of structures have been developed and reported in the literature, and some of them include temperature compensation techniques. In real applications, however, digital processing technologies have proven their value by: (i) offering a very interesting way to acquire information from the structures under test; (ii) applying methodologies to provide a robust analysis; and (iii) performing a damage identification with a practical useful accuracy. This work shows the implementation of an SHM system based on the use of piezoelectric (PZT) sensors for inspecting a structure subjected to temperature changes. The methodology includes the use of multivariate analysis, sensor data fusion and machine learning approaches. The methodology is tested and evaluated with aluminum and composite structures that are subjected to temperature variations. Results show that damage can be detected and classified in all of the cases in spite of the temperature changes.

Damage localization by statistical evaluation of signal-processed mode shapes

DEFF Research Database (Denmark)

Ulriksen, Martin Dalgaard; Damkilde, Lars

2015-01-01

Due to their inherent ability to provide structural information on a local level, mode shapes and their derivatives are utilized extensively for structural damage identification. Typically, more or less advanced mathematical methods are implemented to identify damage-induced discontinuities in th...... is conducted on the basis of T2-statistics. The proposed method is demonstrated in the context of analytical work with a free-vibrating Euler-Bernoulli beam under noisy conditions.......) and subsequent application of a generalized discrete Teager-Kaiser energy operator (GDTKEO) to identify damage-induced mode shape discontinuities. In order to evaluate whether the identified discontinuities are in fact damage-induced, outlier analysis of principal components of the signal-processed mode shapes...

Detecting Damage in Composite Material Using Nonlinear Elastic Wave Spectroscopy Methods

Science.gov (United States)

Meo, Michele; Polimeno, Umberto; Zumpano, Giuseppe

2008-05-01

Modern aerospace structures make increasing use of fibre reinforced plastic composites, due to their high specific mechanical properties. However, due to their brittleness, low velocity impact can cause delaminations beneath the surface, while the surface may appear to be undamaged upon visual inspection. Such damage is called barely visible impact damage (BVID). Such internal damages lead to significant reduction in local strengths and ultimately could lead to catastrophic failures. It is therefore important to detect and monitor damages in high loaded composite components to receive an early warning for a well timed maintenance of the aircraft. Non-linear ultrasonic spectroscopy methods are promising damage detection and material characterization tools. In this paper, two different non-linear elastic wave spectroscopy (NEWS) methods are presented: single mode nonlinear resonance ultrasound (NRUS) and nonlinear wave modulation technique (NWMS). The NEWS methods were applied to detect delamination damage due to low velocity impact (<12 J) on various composite plates. The results showed that the proposed methodology appear to be highly sensitive to the presence of damage with very promising future NDT and structural health monitoring applications.

Coupling image processing and stress analysis for damage identification in a human premolar tooth.

Science.gov (United States)

Andreaus, U; Colloca, M; Iacoviello, D

2011-08-01

Non-carious cervical lesions are characterized by the loss of dental hard tissue at the cement-enamel junction (CEJ). Exceeding stresses are therefore generated in the cervical region of the tooth that cause disruption of the bonds between the hydroxyapatite crystals, leading to crack formation and eventual loss of enamel and the underlying dentine. Damage identification was performed by image analysis techniques and allowed to quantitatively assess changes in teeth. A computerized two-step procedure was generated and applied to the first left maxillary human premolar. In the first step, dental images were digitally processed by a segmentation method in order to identify the damage. The considered morphological properties were the enamel thickness and total area, the number of fragments in which the enamel is chipped. The information retrieved by the data processing of the section images allowed to orient the stress investigation toward selected portions of the tooth. In the second step, a three-dimensional finite element model based on CT images of both the tooth and the periodontal ligament was employed to compare the changes occurring in the stress distributions in normal occlusion and malocclusion. The stress states were analyzed exclusively in the critical zones designated in the first step. The risk of failure at the CEJ and of crack initiation at the dentin-enamel junction through the quantification of first and third principal stresses, von Mises stress, and normal and tangential stresses, were also estimated. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

The biospeckle method for early damage detection of fruits

Science.gov (United States)

Yan, Lei; Liu, Jiaxin; Men, Sen

2017-07-01

In the field of fruits damage assessment, biospeckle activity is considered relevant to quality properties of plants, such us damage, aging, or diseases. In this paper, biospeckle technique was applied to identify the early bruising of apples. Then a total of 50 undamaged apples were determined to be artificially bruised as samples. Three methods (Fujii, GD, and LSTCA) were used to extract effective information from these speckle images for measuring the intensity of biospeckle activity. The results showed that for all of three methods, the biospeckle activities of the undamaged areas in apple were similar; after the hit, the damaged area showed a lower biospeckle activity. It can be concluded that early bruising can be identified by biospeckle technique.

Active damage detection method based on support vector machine and impulse response

International Nuclear Information System (INIS)

Taniguchi, Ryuta; Mita, Akira

2004-01-01

An active damage detection method was proposed to characterize damage in bolted joints. The purpose of this study is to propose a damage detection method that can obtain the detailed information of the damage by creating feature vectors for pattern recognition. In the proposed method, the wavelet transform is applied to the sensor signals, and the feature vectors are defined by second power average of the amplitude. The feature vectors generated by experiments were successfully used as the training data for Support Vector Machine (SVM). By applying the wavelet transform to time-frequency analysis, the accuracy of pattern recognition was raised in both correlation coefficient and SVM applications. Moreover, the SVM could identify the damage with very strong discernment capability than others. Applicability of the proposed method was successfully demonstrated. (author)

Identification methods of irradiated food

International Nuclear Information System (INIS)

Raffi, J.J.

1991-01-01

After a general review of the different possible methods, the stress is put upon the ones close to application: electron spin resonance, thermoluminescence and method of lipids. The problem of the specificity of each method is discussed (proof or presumption): they are then placed in the context of the programme of identification of irradiated foods just co-organized by the author with the Community Bureau of Reference (CEC) [fr

The modal surface interpolation method for damage localization

Science.gov (United States)

Pina Limongelli, Maria

2017-05-01

The Interpolation Method (IM) has been previously proposed and successfully applied for damage localization in plate like structures. The method is based on the detection of localized reductions of smoothness in the Operational Deformed Shapes (ODSs) of the structure. The IM can be applied to any type of structure provided the ODSs are estimated accurately in the original and in the damaged configurations. If the latter circumstance fails to occur, for example when the structure is subjected to an unknown input(s) or if the structural responses are strongly corrupted by noise, both false and missing alarms occur when the IM is applied to localize a concentrated damage. In order to overcome these drawbacks a modification of the method is herein investigated. An ODS is the deformed shape of a structure subjected to a harmonic excitation: at resonances the ODS are dominated by the relevant mode shapes. The effect of noise at resonance is usually lower with respect to other frequency values hence the relevant ODS are estimated with higher reliability. Several methods have been proposed to reliably estimate modal shapes in case of unknown input. These two circumstances can be exploited to improve the reliability of the IM. In order to reduce or eliminate the drawbacks related to the estimation of the ODSs in case of noisy signals, in this paper is investigated a modified version of the method based on a damage feature calculated considering the interpolation error relevant only to the modal shapes and not to all the operational shapes in the significant frequency range. Herein will be reported the comparison between the results of the IM in its actual version (with the interpolation error calculated summing up the contributions of all the operational shapes) and in the new proposed version (with the estimation of the interpolation error limited to the modal shapes).

Steady State Shift Damage Localization in a Residential-Sized Wind Turbine Blade

DEFF Research Database (Denmark)

Markvart, Morten Kusk; Sekjær, Claus; Bull, Thomas

2017-01-01

methodological premise is that of mapping a model-based damage distribution to experimental vibration features from the healthy and damaged states. Damage is then localized when a postulated damage distribution yields a, under ideal conditions, perfect mapping. The S3DL method relies on a theoretical model that......, in an experimental procedure with a plate-like structure, thus the present study serves to investigate the applicability of the method for more complex structures; in this case, a residential-sized wind turbine blade, which has been designed specifically for damage identification purposes. The blade consists of two...... parts that are bolted together along the leading and trailing edges, hence enabling introduction of stiffness-related damages by untightening a number of bolts. The paper studies two damage cases: failure of the trailing edge and a mass modification....

Concrete damage diagnosed using the non-classical nonlinear acoustic method

International Nuclear Information System (INIS)

Dao, Zhou; Xiao-Zhou, Liu; Xiu-Fen, Gong; E, Nazarov V; Li, Ma

2009-01-01

It is known that the strength of concrete is seriously affected by damage and cracking. In this paper, six concrete samples under different damage levels are studied. The experimental results show a linear dependence of the resonance frequency shift on strain amplitude at the fundamental frequency, and approximate quadratic dependence of the amplitudes of the second and third harmonics on strain amplitude at the fundamental frequency as well. In addition, the amplitude of the third harmonics is shown to increase with the increase of damage level, which is even higher than that of the second harmonics in samples with higher damage levels. These are three properties of non-classical nonlinear acoustics. The nonlinear parameters increase from 10 6 to 10 8 with damage level, and are more sensitive to the damage level of the concrete than the linear parameters obtained by using traditional acoustics methods. So, this method based on non-classical nonlinear acoustics may provide a better means of non-destructive testing (NDT) of concrete and other porous materials

Damage identification of beam structures using free response shapes obtained by use of a continuously scanning laser Doppler vibrometer system

Science.gov (United States)

Xu, Y. F.; Chen, Da-Ming; Zhu, W. D.

2017-08-01

Spatially dense operating deflection shapes and mode shapes can be rapidly obtained by use of a continuously scanning laser Doppler vibrometer (CSLDV) system, which sweeps its laser spot over a vibrating structure surface. This paper introduces a new type of vibration shapes called a free response shape (FRS) that can be obtained by use of a CSLDV system, and a new damage identification methodology using FRSs is developed for beam structures. An analytical expression of FRSs of a damped beam structure is derived, and FRSs from the analytical expression compare well with those from a finite element model. In the damage identification methodology, a free-response damage index (FRDI) is proposed, and damage regions can be identified near neighborhoods with consistently high values of FRDIs associated with different modes; an auxiliary FRDI is defined to assist identification of the neighborhoods. A FRDI associated with a mode consists of differences between curvatures of FRSs associated with the mode in a number of half-scan periods of a CSLDV system and those from polynomials that fit the FRSs with properly determined orders. A convergence index is proposed to determine the proper order of a polynomial fit. One advantage of the methodology is that the FRDI does not require any baseline information of an undamaged beam structure, if it is geometrically smooth and made of materials that have no stiffness and mass discontinuities. Another advantage is that FRDIs associated with multiple modes can be obtained using free response of a beam structure measured by a CSLDV system in one scan. The number of half-scan periods for calculation of the FRDI associated with a mode can be determined by use of the short-time Fourier transform. The proposed methodology was numerically and experimentally applied to identify damage in beam structures; effects of the scan frequency of a CSLDV system on qualities of obtained FRSs were experimentally investigated.

Critical and subcritical damage monitoring of bonded composite repairs using innovative non-destructive techniques

Science.gov (United States)

Grammatikos, S. A.; Kordatos, E. Z.; Aggelis, D. G.; Matikas, T. E.; Paipetis, A. S.

2012-04-01

Infrared Thermography (IrT) has been shown to be capable of detecting and monitoring service induced damage of repair composite structures. Full-field imaging, along with portability are the primary benefits of the thermographic technique. On-line lock-in thermography has been reported to successfully monitor damage propagation or/and stress concentration in composite coupons, as mechanical stresses in structures induce heat concentration phenomena around flaws. During mechanical fatigue, cyclic loading plays the role of the heating source and this allows for critical and subcritical damage identification and monitoring using thermography. The Electrical Potential Change Technique (EPCT) is a new method for damage identification and monitoring during loading. The measurement of electrical potential changes at specific points of Carbon Fiber Reinforced Polymers (CFRPs) under load are reported to enable the monitoring of strain or/and damage accumulation. Along with the aforementioned techniques Finally, Acoustic Emission (AE) method is well known to provide information about the location and type of damage. Damage accumulation due to cyclic loading imposes differentiation of certain parameters of AE like duration and energy. Within the scope of this study, infrared thermography is employed along with AE and EPCT methods in order to assess the integrity of bonded repair patches on composite substrates and to monitor critical and subcritical damage induced by the mechanical loading. The combined methodologies were effective in identifying damage initiation and propagation of bonded composite repairs.

Anisotropic Elastoplastic Damage Mechanics Method to Predict Fatigue Life of the Structure

Directory of Open Access Journals (Sweden)

Hualiang Wan

2016-01-01

Full Text Available New damage mechanics method is proposed to predict the low-cycle fatigue life of metallic structures under multiaxial loading. The microstructure mechanical model is proposed to simulate anisotropic elastoplastic damage evolution. As the micromodel depends on few material parameters, the present method is very concise and suitable for engineering application. The material parameters in damage evolution equation are determined by fatigue experimental data of standard specimens. By employing further development on the ANSYS platform, the anisotropic elastoplastic damage mechanics-finite element method is developed. The fatigue crack propagation life of satellite structure is predicted using the present method and the computational results comply with the experimental data very well.

Continuum damage mechanics method for fatigue growth of surface cracks

International Nuclear Information System (INIS)

Feng Xiqiao; He Shuyan

1997-01-01

With the background of leak-before-break (LBB) analysis of pressurized vessels and pipes in nuclear plants, the fatigue growth problem of either circumferential or longitudinal semi-elliptical surface cracks subjected to cyclic loading is studied by using a continuum damage mechanics method. The fatigue damage is described by a scalar damage variable. From the damage evolution equation at the crack tip, a crack growth equation similar to famous Paris' formula is derived, which shows the physical meaning of Paris' formula. Thereby, a continuum damage mechanics approach is developed to analyze the configuration evolution of surface cracks during fatigue growth

A Damage Prognosis Method of Girder Structures Based on Wavelet Neural Networks

Directory of Open Access Journals (Sweden)

Rumian Zhong

2014-01-01

Full Text Available Based on the basic theory of wavelet neural networks and finite element model updating method, a basic framework of damage prognosis method is proposed in this paper. Firstly, a damaged I-steel beam model testing is used to verify the feasibility and effectiveness of the proposed damage prognosis method. The results show that the predicted results of the damage prognosis method and the measured results are very well consistent, and the maximum error is less than 5%. Furthermore, Xinyihe Bridge in the Beijing-Shanghai Highway is selected as the engineering background, and the damage prognosis is conducted based on the data from the structural health monitoring system. The results show that the traffic volume will increase and seasonal differences will decrease in the next year and a half. The displacement has a slight increase and seasonal characters in the critical section of mid span, but the strain will increase distinctly. The analysis results indicate that the proposed method can be applied to the damage prognosis of girder bridge structures and has the potential for the bridge health monitoring and safety prognosis.

Investigation of Time Series Representations and Similarity Measures for Structural Damage Pattern Recognition

Science.gov (United States)

Swartz, R. Andrew

2013-01-01

This paper investigates the time series representation methods and similarity measures for sensor data feature extraction and structural damage pattern recognition. Both model-based time series representation and dimensionality reduction methods are studied to compare the effectiveness of feature extraction for damage pattern recognition. The evaluation of feature extraction methods is performed by examining the separation of feature vectors among different damage patterns and the pattern recognition success rate. In addition, the impact of similarity measures on the pattern recognition success rate and the metrics for damage localization are also investigated. The test data used in this study are from the System Identification to Monitor Civil Engineering Structures (SIMCES) Z24 Bridge damage detection tests, a rigorous instrumentation campaign that recorded the dynamic performance of a concrete box-girder bridge under progressively increasing damage scenarios. A number of progressive damage test case datasets and damage test data with different damage modalities are used. The simulation results show that both time series representation methods and similarity measures have significant impact on the pattern recognition success rate. PMID:24191136

Investigation of Time Series Representations and Similarity Measures for Structural Damage Pattern Recognition

Directory of Open Access Journals (Sweden)

Wenjia Liu

2013-01-01

Full Text Available This paper investigates the time series representation methods and similarity measures for sensor data feature extraction and structural damage pattern recognition. Both model-based time series representation and dimensionality reduction methods are studied to compare the effectiveness of feature extraction for damage pattern recognition. The evaluation of feature extraction methods is performed by examining the separation of feature vectors among different damage patterns and the pattern recognition success rate. In addition, the impact of similarity measures on the pattern recognition success rate and the metrics for damage localization are also investigated. The test data used in this study are from the System Identification to Monitor Civil Engineering Structures (SIMCES Z24 Bridge damage detection tests, a rigorous instrumentation campaign that recorded the dynamic performance of a concrete box-girder bridge under progressively increasing damage scenarios. A number of progressive damage test case datasets and damage test data with different damage modalities are used. The simulation results show that both time series representation methods and similarity measures have significant impact on the pattern recognition success rate.

GPS on Every Roof, GPS Sensor Network for Post-Seismic Building-Wise Damage Identification

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Kenji Oguni

2013-12-01

Full Text Available Development of wireless sensor network equipped with GPS for post-seismic building-wise damage identification is presented in this paper. This system is called GPS on Every Roof. Sensor node equipped with GPS antenna and receiver is installed on the top of the roof of each and every building. The position of this sensor node is measured before and after earthquake. The final goal of this system is to i identify the displacement of the roof of each house and ii collect the information of displacement of the roof of the houses through wireless communication. Superposing this information on GIS, building-wise damage distribution due to earthquake can be obtained. The system overview, hardware and some of the key components of the system such as on-board GPS relative positioning algorithm to achieve the accuracy in the order of several centimeters are described in detail. Also, the results from a field experiment using a wireless sensor network with 39 sensor nodes are presented.

Covariance of dynamic strain responses for structural damage detection

Science.gov (United States)

Li, X. Y.; Wang, L. X.; Law, S. S.; Nie, Z. H.

2017-10-01

A new approach to address the practical problems with condition evaluation/damage detection of structures is proposed based on the distinct features of a new damage index. The covariance of strain response function (CoS) is a function of modal parameters of the structure. A local stiffness reduction in structure would cause monotonous increase in the CoS. Its sensitivity matrix with respect to local damages of structure is negative and narrow-banded. The damage extent can be estimated with an approximation to the sensitivity matrix to decouple the identification equations. The CoS sensitivity can be calibrated in practice from two previous states of measurements to estimate approximately the damage extent of a structure. A seven-storey plane frame structure is numerically studied to illustrate the features of the CoS index and the proposed method. A steel circular arch in the laboratory is tested. Natural frequencies changed due to damage in the arch and the damage occurrence can be judged. However, the proposed CoS method can identify not only damage happening but also location, even damage extent without need of an analytical model. It is promising for structural condition evaluation of selected components.

Damage approach: A new method for topology optimization with local stress constraints

DEFF Research Database (Denmark)

Verbart, Alexander; Langelaar, Matthijs; van Keulen, Fred

2016-01-01

In this paper, we propose a new method for topology optimization with local stress constraints. In this method, material in which a stress constraint is violated is considered as damaged. Since damaged material will contribute less to the overall performance of the structure, the optimizer...... will promote a design with a minimal amount of damaged material. We tested the method on several benchmark problems, and the results show that the method is a viable alternative for conventional stress-based approaches based on constraint relaxation followed by constraint aggregation....

Flexibility-based structural damage identification using Gauss ...

Indian Academy of Sciences (India)

... structural damages in civil infrastructure, such as high-rise buildings, long-span ... tion is widely used in bridges and buildings today because it is easy and ..... The objective of this paper is to design a mathematical algo- ..... Single damage.

On the formulation, parameter identification and numerical integration of the EMMI model :plasticity and isotropic damage.

Energy Technology Data Exchange (ETDEWEB)

Bammann, Douglas J.; Johnson, G. C. (University of California, Berkeley, CA); Marin, Esteban B.; Regueiro, Richard A. (University of Colorado, Boulder, CO)

2006-01-01

In this report we present the formulation of the physically-based Evolving Microstructural Model of Inelasticity (EMMI) . The specific version of the model treated here describes the plasticity and isotropic damage of metals as being currently applied to model the ductile failure process in structural components of the W80 program . The formulation of the EMMI constitutive equations is framed in the context of the large deformation kinematics of solids and the thermodynamics of internal state variables . This formulation is focused first on developing the plasticity equations in both the relaxed (unloaded) and current configurations. The equations in the current configuration, expressed in non-dimensional form, are used to devise the identification procedure for the plasticity parameters. The model is then extended to include a porosity-based isotropic damage state variable to describe the progressive deterioration of the strength and mechanical properties of metals induced by deformation . The numerical treatment of these coupled plasticity-damage constitutive equations is explained in detail. A number of examples are solved to validate the numerical implementation of the model.

New Waste Beverage Cans Identification Method

Directory of Open Access Journals (Sweden)

Firmansyah Burlian

2016-05-01

Full Text Available The primary emphasis of this work is on the development of a new waste beverage cans identification method for automated beverage cans sorting systems known as the SVS system. The method described involved window-based subdivision of the image into X-cells, construction of X-candidate template for N-cells, calculation of matching scores of reference templates for the N-cells image, and application of matching score to identify the grade of the object. The SVS system performance for correct beverage cans grade identification is 95.17% with estimated throughput of 21,600 objects per hour with a conveyor belt width of 18˝. The weight of the throughput depends on the size and type of the objects.

Damage detection in multilayered fiber-metal laminates using guided-wave phased array

Energy Technology Data Exchange (ETDEWEB)

Maghsoodi, Ameneh; Ohadi, Abdolrezap; Sadighi, Mojtaba; Amindavar, Hamidreza [Amirkabir University, Tehran (Iran, Islamic Republic of)

2016-05-15

This study employs the Lamb wave method to detect damage in Fiber-metal laminates (FMLs). The method is based on quasiisotropic behavior approximation and beam forming techniques. Delay and sum and minimum variance distorsionless response beam formers are applied to a uniform linear phased array. The simulation in finite element software is conducted to evaluate the performance of the presented procedure. The two types of damage studied are the following: (1) Delamination between fiber-epoxy and metal layers and (2) crack on the metal layer. The present study has the following important contributions: (1) Health monitoring of multi-damaged FMLs using Lamb waves and beam forming technique, (2) detection of damage type, (3) detection of damage size by 1D phased array, and (4) identification of damages that occurred very close to the laminate edges or close to each other.

Probability of identification: a statistical model for the validation of qualitative botanical identification methods.

Science.gov (United States)

LaBudde, Robert A; Harnly, James M

2012-01-01

A qualitative botanical identification method (BIM) is an analytical procedure that returns a binary result (1 = Identified, 0 = Not Identified). A BIM may be used by a buyer, manufacturer, or regulator to determine whether a botanical material being tested is the same as the target (desired) material, or whether it contains excessive nontarget (undesirable) material. The report describes the development and validation of studies for a BIM based on the proportion of replicates identified, or probability of identification (POI), as the basic observed statistic. The statistical procedures proposed for data analysis follow closely those of the probability of detection, and harmonize the statistical concepts and parameters between quantitative and qualitative method validation. Use of POI statistics also harmonizes statistical concepts for botanical, microbiological, toxin, and other analyte identification methods that produce binary results. The POI statistical model provides a tool for graphical representation of response curves for qualitative methods, reporting of descriptive statistics, and application of performance requirements. Single collaborator and multicollaborative study examples are given.

Distribution patterns of postmortem damage in human mitochondrial DNA

DEFF Research Database (Denmark)

Gilbert, M Thomas P; Willerslev, Eske; Hansen, Anders J

2002-01-01

1 (HVR1) and cytochrome oxidase subunit III genes. A comparison of damaged sites within and between the regions reveals that damage hotspots exist and that, in the HVR1, these correlate with sites known to have high in vivo mutation rates. Conversely, HVR1 subregions with known structural function......, such as MT5, have lower in vivo mutation rates and lower postmortem-damage rates. The postmortem data also identify a possible functional subregion of the HVR1, termed "low-diversity 1," through the lack of sequence damage. The amount of postmortem damage observed in mitochondrial coding regions...... was significantly lower than in the HVR1, and, although hotspots were noted, these did not correlate with codon position. Finally, a simple method for the identification of incorrect archaeological haplogroup designations is introduced, on the basis of the observed spectrum of postmortem damage....

System Identification Methods for Aircraft Flight Control Development and Validation

Science.gov (United States)

1995-10-01

System-identification methods compose a mathematical model, or series of models, : from measurements of inputs and outputs of dynamic systems. This paper : discusses the use of frequency-domain system-identification methods for the : development and ...

Portraits of Benvenuto Cellini and Anthropological Methods of Their Identification

Science.gov (United States)

Nasobin, Oleg

2016-01-01

Modern methods of biometric identification are increasingly applied in order to attribute works of art. They are based on developments in the 19th century anthropological methods. So, this article describes how the successional anthropological methods were applied for the identification of Benvenuto Cellini's portraits. Objective comparison of…

Identification of characteristic frequencies of damaged railway tracks using field hammer test measurements

Science.gov (United States)

Oregui, M.; Li, Z.; Dollevoet, R.

2015-03-01

In this paper, the feasibility of the Frequency Response Function (FRF)-based statistical method to identify the characteristic frequencies of railway track defects is studied. The method compares a damaged track state to a healthy state based on non-destructive field hammer test measurements. First, a study is carried out to investigate the repeatability of hammer tests in railway tracks. By changing the excitation and measurement locations it is shown that the variability introduced by the test process is negligible. Second, following the concepts of control charts employed in process monitoring, a method to define an approximate healthy state is introduced by using hammer test measurements at locations without visual damage. Then, the feasibility study includes an investigation into squats (i.e. a major type of rail surface defect) of varying severity. The identified frequency ranges related to squats agree with those found in an extensively validated vehicle-borne detection system. Therefore, the FRF-based statistical method in combination with the non-destructive hammer test measurements has the potential to be employed to identify the characteristic frequencies of damaged conditions in railway tracks in the frequency range of 300-3000 Hz.

Response-only method for damage detection of beam-like structures using high accuracy frequencies with auxiliary mass spatial probing

Science.gov (United States)

Zhong, Shuncong; Oyadiji, S. Olutunde; Ding, Kang

2008-04-01

This paper proposes a new approach based on auxiliary mass spatial probing using spectral centre correction method (SCCM), to provide a simple solution for damage detection by just using the response time history of beam-like structures. The natural frequencies of a damaged beam with a traversing auxiliary mass change due to change in the inertia of the beam as the auxiliary mass is traversed along the beam, as well as the point-to-point variations in the flexibility of the beam. Therefore the auxiliary mass can enhance the effects of the crack on the dynamics of the beam and, therefore, facilitate the identification and location of damage in the beam. That is, the auxiliary mass can be used to probe the dynamic characteristic of the beam by traversing the mass from one end of the beam to the other. However, it is impossible to obtain accurate modal frequencies by the direct operation of the fast Fourier transform (FFT) of the response data of the structure because the frequency spectrum can be only calculated from limited sampled time data which results in the well-known leakage effect. SCCM is identical to the energy centrobaric correction method (ECCM) which is a practical and effective method used in rotating mechanical fault diagnosis and which resolves the shortcoming of FFT and can provide high accuracy estimate of frequency, amplitude and phase. In the present work, the modal responses of damaged simply supported beams with auxiliary mass are computed using the finite element method (FEM). The graphical plots of the natural frequencies calculated by SCCM versus axial location of auxiliary mass are obtained. However, it is difficult to locate the crack directly from the curve of natural frequencies. A simple and fast method, the derivatives of natural frequency curve, is proposed in the paper which can provide crack information for damage detection of beam-like structures. The efficiency and practicability of the proposed method is illustrated via numerical

Damage evaluation by a guided wave-hidden Markov model based method

Science.gov (United States)

Mei, Hanfei; Yuan, Shenfang; Qiu, Lei; Zhang, Jinjin

2016-02-01

Guided wave based structural health monitoring has shown great potential in aerospace applications. However, one of the key challenges of practical engineering applications is the accurate interpretation of the guided wave signals under time-varying environmental and operational conditions. This paper presents a guided wave-hidden Markov model based method to improve the damage evaluation reliability of real aircraft structures under time-varying conditions. In the proposed approach, an HMM based unweighted moving average trend estimation method, which can capture the trend of damage propagation from the posterior probability obtained by HMM modeling is used to achieve a probabilistic evaluation of the structural damage. To validate the developed method, experiments are performed on a hole-edge crack specimen under fatigue loading condition and a real aircraft wing spar under changing structural boundary conditions. Experimental results show the advantage of the proposed method.

Reliability Study Regarding the Use of Histogram Similarity Methods for Damage Detection

Directory of Open Access Journals (Sweden)

Nicoleta Gillich

2013-01-01

Full Text Available The paper analyses the reliability of three dissimilarity estimators to compare histograms, as support for a frequency-based damage detection method, able to identify structural changes in beam-like structures. First a brief presentation of the own developed damage detection method is made, with focus on damage localization. It consists actually in comparing a histogram derived from measurement results, with a large series of histograms, namely the damage location indexes for all locations along the beam, obtained by calculus. We tested some dissimilarity estimators like the Minkowski-form Distances, the Kullback-Leibler Divergence and the Histogram Intersection and found the Minkowski Distance as the method providing best results. It was tested for numerous locations, using real measurement results and with results artificially debased by noise, proving its reliability.

Impact of identity theft on methods of identification.

Science.gov (United States)

McLemore, Jerri; Hodges, Walker; Wyman, Amy

2011-06-01

Responsibility for confirming a decedent's identity commonly falls on the shoulders of the coroner or medical examiner. Misidentification of bodies results in emotional turmoil for the next-of-kin and can negatively impact the coroner's or medical examiner's career. To avoid such mishaps, the use of scientific methods to establish a positive identification is advocated. The use of scientific methods of identification may not be reliable in cases where the decedent had assumed the identity of another person. Case studies of erroneously identified bodies due to identity theft from the state medical examiner offices in Iowa and New Mexico are presented. This article discusses the scope and major concepts of identity theft and how identity theft prevents the guarantee of a positive identification.

Process identification method based on the Z transformation; Methode d'identification de processus par la transformation en Z

Energy Technology Data Exchange (ETDEWEB)

Zwingelstein, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

A simple method is described for identifying the transfer function of a linear retard-less system, based on the inversion of the Z transformation of the transmittance using a computer. It is assumed in this study that the signals at the entrance and at the exit of the circuit considered are of the deterministic type. The study includes: the theoretical principle of the inversion of the Z transformation, details about programming simulation, and identification of filters whose degrees vary from the first to the fifth order. (authors) [French] On decrit une methode simple d'identification de fonction de transfert d'un systeme lineaire sans retard, qui repose sur l'inversion de la transformee en Z de la transmittance a l'aide d'un calculateur. On suppose dans cette etude, que les signaux a l'entree et a la sortie du circuit considere sont de type deterministe. L'etude comporte: le principe theorique de l'inversion de la transformation en Z, les details de la programmation, la simulation et l'identification de filtres dont le degre varie du premier au cinquieme ordre. (auteurs)

Identification methods for irradiated wheat

International Nuclear Information System (INIS)

Zhu Shengtao; Kume, Tamikazu; Ishigaki, Isao.

1992-02-01

The effect of irradiation on wheat seeds was examined using various kinds of analytical methods for the identification of irradiated seeds. In germination test, the growth of sprouts was markedly inhibited at 500Gy, which was not affected by storage. The decrease in germination percentage was detected at 3300Gy. The results of enzymatic activity change in the germ measured by Vita-Scope germinator showed that the seeds irradiated at 10kGy could be identified. The content of amino acids in ungerminated and germinated seeds were analyzed. Irradiation at 10kGy caused the decrease of lysine content but the change was small which need very careful operation to detect it. The chemiluminescence intensity increased with radiation dose and decreased during storage. The wheat irradiated at 10kGy could be identified even after 3 months storage. In the electron spin resonance (ESR) spectrum analysis, the signal intensity with the g value f 2.0055 of skinned wheat seeds increased with radiation dose. Among these methods, germination test was the most sensitive and effective for identification of irradiated wheat. (author)

Damage Detection for Continuous Bridge Based on Static-Dynamic Condensation and Extended Kalman Filtering

Directory of Open Access Journals (Sweden)

Haoxiang He

2014-01-01

Full Text Available As an effective and classical method about physical parameter identification, extended Kalman filtering (EKF algorithm is widely used in structural damage identification, but the equations and solutions for the structure with bending deformation are not established based on EKF. The degrees of freedom about rotation can be eliminated by the static condensation method, and the dynamic condensation method considering Rayleigh damping is proposed in order to establish the equivalent and simplified modal based on complex finite element model such as continuous girder bridge. According to the requirement of bridge inspection and health monitoring, the online and convenient damage detection method based on EKF is presented. The impact excitation can be generated only on one location by one hammer actuator, and the signal in free vibration is analyzed. The deficiency that the complex excitation information is needed based on the traditional method is overcome. As a numerical example, a three-span continuous girder bridge is simulated, and the corresponding stiffness, the damage location and degree, and the damping parameter are identified accurately. It is verified that the method is suitable for the dynamic signal with high noise-signal ratio; the convergence speed is fast and this method is feasible for application.

On-Line Multi-Damage Scanning Spatial-Wavenumber Filter Based Imaging Method for Aircraft Composite Structure

Directory of Open Access Journals (Sweden)

Yuanqiang Ren

2017-05-01

Full Text Available Structural health monitoring (SHM of aircraft composite structure is helpful to increase reliability and reduce maintenance costs. Due to the great effectiveness in distinguishing particular guided wave modes and identifying the propagation direction, the spatial-wavenumber filter technique has emerged as an interesting SHM topic. In this paper, a new scanning spatial-wavenumber filter (SSWF based imaging method for multiple damages is proposed to conduct on-line monitoring of aircraft composite structures. Firstly, an on-line multi-damage SSWF is established, including the fundamental principle of SSWF for multiple damages based on a linear piezoelectric (PZT sensor array, and a corresponding wavenumber-time imaging mechanism by using the multi-damage scattering signal. Secondly, through combining the on-line multi-damage SSWF and a PZT 2D cross-shaped array, an image-mapping method is proposed to conduct wavenumber synthesis and convert the two wavenumber-time images obtained by the PZT 2D cross-shaped array to an angle-distance image, from which the multiple damages can be directly recognized and located. In the experimental validation, both simulated multi-damage and real multi-damage introduced by repeated impacts are performed on a composite plate structure. The maximum localization error is less than 2 cm, which shows good performance of the multi-damage imaging method. Compared with the existing spatial-wavenumber filter based damage evaluation methods, the proposed method requires no more than the multi-damage scattering signal and can be performed without depending on any wavenumber modeling or measuring. Besides, this method locates multiple damages by imaging instead of the geometric method, which helps to improve the signal-to-noise ratio. Thus, it can be easily applied to on-line multi-damage monitoring of aircraft composite structures.

Extended Kalman filtering for the detection of damage in linear mechanical structures

Science.gov (United States)

Liu, X.; Escamilla-Ambrosio, P. J.; Lieven, N. A. J.

2009-09-01

This paper addresses the problem of assessing the location and extent of damage in a vibrating structure by means of vibration measurements. Frequency domain identification methods (e.g. finite element model updating) have been widely used in this area while time domain methods such as the extended Kalman filter (EKF) method, are more sparsely represented. The difficulty of applying EKF in mechanical system damage identification and localisation lies in: the high computational cost, the dependence of estimation results on the initial estimation error covariance matrix P(0), the initial value of parameters to be estimated, and on the statistics of measurement noise R and process noise Q. To resolve these problems in the EKF, a multiple model adaptive estimator consisting of a bank of EKF in modal domain was designed, each filter in the bank is based on different P(0). The algorithm was iterated by using the weighted global iteration method. A fuzzy logic model was incorporated in each filter to estimate the variance of the measurement noise R. The application of the method is illustrated by simulated and real examples.

Accurate Lithium-ion battery parameter estimation with continuous-time system identification methods

International Nuclear Information System (INIS)

Xia, Bing; Zhao, Xin; Callafon, Raymond de; Garnier, Hugues; Nguyen, Truong; Mi, Chris

2016-01-01

Highlights: • Continuous-time system identification is applied in Lithium-ion battery modeling. • Continuous-time and discrete-time identification methods are compared in detail. • The instrumental variable method is employed to further improve the estimation. • Simulations and experiments validate the advantages of continuous-time methods. - Abstract: The modeling of Lithium-ion batteries usually utilizes discrete-time system identification methods to estimate parameters of discrete models. However, in real applications, there is a fundamental limitation of the discrete-time methods in dealing with sensitivity when the system is stiff and the storage resolutions are limited. To overcome this problem, this paper adopts direct continuous-time system identification methods to estimate the parameters of equivalent circuit models for Lithium-ion batteries. Compared with discrete-time system identification methods, the continuous-time system identification methods provide more accurate estimates to both fast and slow dynamics in battery systems and are less sensitive to disturbances. A case of a 2"n"d-order equivalent circuit model is studied which shows that the continuous-time estimates are more robust to high sampling rates, measurement noises and rounding errors. In addition, the estimation by the conventional continuous-time least squares method is further improved in the case of noisy output measurement by introducing the instrumental variable method. Simulation and experiment results validate the analysis and demonstrate the advantages of the continuous-time system identification methods in battery applications.

Liability for oil spill damages: issues, methods, and examples

International Nuclear Information System (INIS)

Grigalunas, T.A.; Opaluch, J.J.; Diamantides, J.; Mazzotta, M.

1998-01-01

Liability is an important incentive-based instrument for preventing oil spills and provides a sustainable approach for restoring coastal resources injured by spills. However, the use of liability for environmental damages raises many challenges, including quantification of money measures of damages. In this article, case studies are used to illustrate the issues, methods, and challenges associated with assessing a range of damages, from those that can be measured relatively easily using market information to more 'esoteric', and much more difficult, cases involving non-market-valued losses. Also discussed are issues raised by the new national and international regulatory focus on restoration and by the simplified, compensatory formula used by some states. (author)

Comparison of System Identification Methods using Ambient Bridge Test Data

DEFF Research Database (Denmark)

Andersen, P.; Brincker, Rune; Peeters, B.

1999-01-01

In this paper the performance of four different system identification methods is compared using operational data obtained from an ambient vibration test of the Swiss Z24 highway bridge. The four methods are the frequency domain based peak-picking methods, the polyreference LSCE method, the stocha......In this paper the performance of four different system identification methods is compared using operational data obtained from an ambient vibration test of the Swiss Z24 highway bridge. The four methods are the frequency domain based peak-picking methods, the polyreference LSCE method...

Construction, implementation and testing of an image identification system using computer vision methods for fruit flies with economic importance (Diptera: Tephritidae).

Science.gov (United States)

Wang, Jiang-Ning; Chen, Xiao-Lin; Hou, Xin-Wen; Zhou, Li-Bing; Zhu, Chao-Dong; Ji, Li-Qiang

2017-07-01

Many species of Tephritidae are damaging to fruit, which might negatively impact international fruit trade. Automatic or semi-automatic identification of fruit flies are greatly needed for diagnosing causes of damage and quarantine protocols for economically relevant insects. A fruit fly image identification system named AFIS1.0 has been developed using 74 species belonging to six genera, which include the majority of pests in the Tephritidae. The system combines automated image identification and manual verification, balancing operability and accuracy. AFIS1.0 integrates image analysis and expert system into a content-based image retrieval framework. In the the automatic identification module, AFIS1.0 gives candidate identification results. Afterwards users can do manual selection based on comparing unidentified images with a subset of images corresponding to the automatic identification result. The system uses Gabor surface features in automated identification and yielded an overall classification success rate of 87% to the species level by Independent Multi-part Image Automatic Identification Test. The system is useful for users with or without specific expertise on Tephritidae in the task of rapid and effective identification of fruit flies. It makes the application of computer vision technology to fruit fly recognition much closer to production level. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Damage identification using guided waves on a composite skin-stiffener structure

NARCIS (Netherlands)

Loendersloot, R.; Battley, M.; Tinga, T.

2016-01-01

The potential of using guided waves for damage detection in composite materials has been proven by many researches in the past few years and in particular by the cases studies of the European project SARISTU. In that project integration methods for the piezoelectric wafer active sensors (PWAS),

Computational methods for protein identification from mass spectrometry data.

Directory of Open Access Journals (Sweden)

Leo McHugh

2008-02-01

Full Text Available Protein identification using mass spectrometry is an indispensable computational tool in the life sciences. A dramatic increase in the use of proteomic strategies to understand the biology of living systems generates an ongoing need for more effective, efficient, and accurate computational methods for protein identification. A wide range of computational methods, each with various implementations, are available to complement different proteomic approaches. A solid knowledge of the range of algorithms available and, more critically, the accuracy and effectiveness of these techniques is essential to ensure as many of the proteins as possible, within any particular experiment, are correctly identified. Here, we undertake a systematic review of the currently available methods and algorithms for interpreting, managing, and analyzing biological data associated with protein identification. We summarize the advances in computational solutions as they have responded to corresponding advances in mass spectrometry hardware. The evolution of scoring algorithms and metrics for automated protein identification are also discussed with a focus on the relative performance of different techniques. We also consider the relative advantages and limitations of different techniques in particular biological contexts. Finally, we present our perspective on future developments in the area of computational protein identification by considering the most recent literature on new and promising approaches to the problem as well as identifying areas yet to be explored and the potential application of methods from other areas of computational biology.

[A Method Research on Environmental Damage Assessment of a Truck Rollover Pollution Incident].

Science.gov (United States)

Cai, Feng; Zhao, Shi-ho; Chen, Gang-cai; Xian, Si-shu; Yang, Qing-ling; Zhou, Xian-jie; Yu, Hai

2015-05-01

With high occurrence of sudden water pollution incident, China faces an increasingly severe situation of water environment. In order to deter the acts of environmental pollution, ensure the damaged resources of environment can be restored and compensated, it is very critical to quantify the economic losses caused by the sudden water pollution incident. This paper took truck rollover pollution incidents in Chongqing for an example, established a set of evaluation method for quantifying the environmental damage, and then assessed the environmental damage by the method from four aspects, including the property damage, ecological environment and resources damages, the costs of administrative affairs in emergency disposal, and the costs of investigation and evaluation.

Identification and authentication. Common biometric methods review

OpenAIRE

Lysak, A.

2012-01-01

Major biometric methods used for identification and authentication purposes in modern computing systems are considered in the article. Basic classification, application areas and key differences are given.

Image portion identification methods, image parsing methods, image parsing systems, and articles of manufacture

Science.gov (United States)

Lassahn, Gordon D.; Lancaster, Gregory D.; Apel, William A.; Thompson, Vicki S.

2013-01-08

Image portion identification methods, image parsing methods, image parsing systems, and articles of manufacture are described. According to one embodiment, an image portion identification method includes accessing data regarding an image depicting a plurality of biological substrates corresponding to at least one biological sample and indicating presence of at least one biological indicator within the biological sample and, using processing circuitry, automatically identifying a portion of the image depicting one of the biological substrates but not others of the biological substrates.

Visual method for detecting critical damage in railway contact strips

Science.gov (United States)

Judek, S.; Skibicki, J.

2018-05-01

Ensuring an uninterrupted supply of power in the electric traction is vital for the safety of this important transport system. For this purpose, monitoring and diagnostics of the technical condition of the vehicle’s power supply elements are becoming increasingly common. This paper presents a new visual method for detecting contact strip damage, based on measurement and analysis of the movement of the overhead contact line (OCL) wire. A measurement system configuration with a 2D camera was proposed. The experimental method has shown that contact strips damage can be detected by transverse displacement signal analysis. It has been proven that the velocity signal numerically established on that basis has a comparable level in the case of identical damage, regardless of its location on the surface of the contact strip. The proposed method belongs to the group of contact-less measurements, so it does not require interference with the structure of the catenary network nor the mounting of sensors in its vicinity. Measurement of displacements of the contact wire in 2D space makes it possible to combine the functions of existing diagnostic stands assessing the correctness of the mean contact force control adjustment of the current collector with the elements of the contact strip diagnostics, which involves detecting their damage which may result in overhead contact line rupture.

Mathematical correlation of modal-parameter-identification methods via system-realization theory

Science.gov (United States)

Juang, Jer-Nan

1987-01-01

A unified approach is introduced using system-realization theory to derive and correlate modal-parameter-identification methods for flexible structures. Several different time-domain methods are analyzed and treated. A basic mathematical foundation is presented which provides insight into the field of modal-parameter identification for comparison and evaluation. The relation among various existing methods is established and discussed. This report serves as a starting point to stimulate additional research toward the unification of the many possible approaches for modal-parameter identification.

A Parameter Identification Method for Helicopter Noise Source Identification and Physics-Based Semi-Empirical Modeling

Science.gov (United States)

Greenwood, Eric, II; Schmitz, Fredric H.

2010-01-01

A new physics-based parameter identification method for rotor harmonic noise sources is developed using an acoustic inverse simulation technique. This new method allows for the identification of individual rotor harmonic noise sources and allows them to be characterized in terms of their individual non-dimensional governing parameters. This new method is applied to both wind tunnel measurements and ground noise measurements of two-bladed rotors. The method is shown to match the parametric trends of main rotor Blade-Vortex Interaction (BVI) noise, allowing accurate estimates of BVI noise to be made for operating conditions based on a small number of measurements taken at different operating conditions.

Comparison of identification methods for oral asaccharolytic Eubacterium species.

Science.gov (United States)

Wade, W G; Slayne, M A; Aldred, M J

1990-12-01

Thirty one strains of oral, asaccharolytic Eubacterium spp. and the type strains of E. brachy, E. nodatum and E. timidum were subjected to three identification techniques--protein-profile analysis, determination of metabolic end-products, and the API ATB32A identification kit. Five clusters were obtained from numerical analysis of protein profiles and excellent correlations were seen with the other two methods. Protein profiles alone allowed unequivocal identification.

Nonlinear Dynamic Behavior of Impact Damage in a Composite Skin-Stiffener Structure

Science.gov (United States)

Ooijevaar, T. H.; Rogge, M. D.; Loendersloot, R.; Warnet, L.; Akkerman, R.; deBoer, A.

2013-01-01

One of the key issues in composite structures for aircraft applications is the early identification of damage. Often, service induced damage does not involve visible plastic deformation, but internal matrix related damage, like delaminations. A wide range of technologies, comprising global vibration and local wave propagation methods can be employed for health monitoring purposes. Traditional low frequency modal analysis based methods are linear methods. The effectiveness of these methods is often limited since they rely on a stationary and linear approximation of the system. The nonlinear interaction between a low frequency wave field and a local impact induced skin-stiffener failure is experimentally demonstrated in this paper. The different mechanisms that are responsible for the nonlinearities (opening, closing and contact) of the distorted harmonic waveforms are separated with the help of phase portraits. A basic analytical model is employed to support the observations.

Mathematical correlation of modal parameter identification methods via system realization theory

Science.gov (United States)

Juang, J. N.

1986-01-01

A unified approach is introduced using system realization theory to derive and correlate modal parameter identification methods for flexible structures. Several different time-domain and frequency-domain methods are analyzed and treated. A basic mathematical foundation is presented which provides insight into the field of modal parameter identification for comparison and evaluation. The relation among various existing methods is established and discussed. This report serves as a starting point to stimulate additional research towards the unification of the many possible approaches for modal parameter identification.

Contactless Diagnostics of Turbine Blade Vibration and Damage

International Nuclear Information System (INIS)

Prochazka, Pavel; Vanek, Frantisek

2011-01-01

The study deals with the contactless diagnostic method used for the identification of steam turbine blade strain, vibration and damage. The tip-timing method based on the evaluation of time differences of blade passages in different rotor revolutions has been modified and improved to provide more precise and reliable results. A new approach to the analysis of the amplitude and time differences of impulse signals generated by a blade passage has been applied. Amplitudes and frequencies of vibrations and static position of blades ascertained by the diagnostic process are used to establish the state of blade damage. A contactless diagnostic system VDS-UT based on magneto-resistive sensors was developed in the Institute of Thermomechanics Academy of Sciences of the Czech Republic. The system provides on-line monitoring of vibration amplitudes and frequencies of all blades and notification of possible blade damage. Evaluation of the axial and circumferential components of the deflections by measuring the amplitude of blade impulse signals results in an overall improvement of the method. Using magneto-resistive sensors, blade elongation and untwisting can be determined as well.

Damage Detection of Structures for Ambient Loading Based on Cross Correlation Function Amplitude and SVM

Directory of Open Access Journals (Sweden)

Lin-sheng Huo

2016-01-01

Full Text Available An effective method for the damage detection of skeletal structures which combines the cross correlation function amplitude (CCFA with the support vector machine (SVM is presented in this paper. The proposed method consists of two stages. Firstly, the data features are extracted from the CCFA, which, calculated from dynamic responses and as a representation of the modal shapes of the structure, changes when damage occurs on the structure. The data features are then input into the SVM with the one-against-one (OAO algorithm to classify the damage status of the structure. The simulation data of IASC-ASCE benchmark model and a vibration experiment of truss structure are adopted to verify the feasibility of proposed method. The results show that the proposed method is suitable for the damage identification of skeletal structures with the limited sensors subjected to ambient excitation. As the CCFA based data features are sensitive to damage, the proposed method demonstrates its reliability in the diagnosis of structures with damage, especially for those with minor damage. In addition, the proposed method shows better noise robustness and is more suitable for noisy environments.

Selection of regularization parameter for l1-regularized damage detection

Science.gov (United States)

Hou, Rongrong; Xia, Yong; Bao, Yuequan; Zhou, Xiaoqing

2018-06-01

The l1 regularization technique has been developed for structural health monitoring and damage detection through employing the sparsity condition of structural damage. The regularization parameter, which controls the trade-off between data fidelity and solution size of the regularization problem, exerts a crucial effect on the solution. However, the l1 regularization problem has no closed-form solution, and the regularization parameter is usually selected by experience. This study proposes two strategies of selecting the regularization parameter for the l1-regularized damage detection problem. The first method utilizes the residual and solution norms of the optimization problem and ensures that they are both small. The other method is based on the discrepancy principle, which requires that the variance of the discrepancy between the calculated and measured responses is close to the variance of the measurement noise. The two methods are applied to a cantilever beam and a three-story frame. A range of the regularization parameter, rather than one single value, can be determined. When the regularization parameter in this range is selected, the damage can be accurately identified even for multiple damage scenarios. This range also indicates the sensitivity degree of the damage identification problem to the regularization parameter.

Multivariate methods for particle identification

CERN Document Server

Visan, Cosmin

2013-01-01

The purpose of this project was to evaluate several MultiVariate methods in order to determine which one, if any, offers better results in Particle Identification (PID) than a simple n$\\sigma$ cut on the response of the ALICE PID detectors. The particles considered in the analysis were Pions, Kaons and Protons and the detectors used were TPC and TOF. When used with the same input n$\\sigma$ variables, the results show similar perfoance between the Rectangular Cuts Optimization method and the simple n$\\sigma$ cuts. The method MLP and BDT show poor results for certain ranges of momentum. The KNN method is the best performing, showing similar results for Pions and Protons as the Cuts method, and better results for Kaons. The extension of the methods to include additional input variables leads to poor results, related to instabilities still to be investigated.

A virtual closed loop method for closed loop identification

NARCIS (Netherlands)

Agüero, J.C.; Goodwin, G.C.; Hof, Van den P.M.J.

2011-01-01

Indirect methods for the identification of linear plant models on the basis of closed loop data are based on the use of (reconstructed) input signals that are uncorrelated with the noise. This generally requires exact (linear) controller knowledge. On the other hand, direct identification requires

A Time-Domain Structural Damage Detection Method Based on Improved Multiparticle Swarm Coevolution Optimization Algorithm

Directory of Open Access Journals (Sweden)

Shao-Fei Jiang

2014-01-01

Full Text Available Optimization techniques have been applied to structural health monitoring and damage detection of civil infrastructures for two decades. The standard particle swarm optimization (PSO is easy to fall into the local optimum and such deficiency also exists in the multiparticle swarm coevolution optimization (MPSCO. This paper presents an improved MPSCO algorithm (IMPSCO firstly and then integrates it with Newmark’s algorithm to localize and quantify the structural damage by using the damage threshold proposed. To validate the proposed method, a numerical simulation and an experimental study of a seven-story steel frame were employed finally, and a comparison was made between the proposed method and the genetic algorithm (GA. The results show threefold: (1 the proposed method not only is capable of localization and quantification of damage, but also has good noise-tolerance; (2 the damage location can be accurately detected using the damage threshold proposed in this paper; and (3 compared with the GA, the IMPSCO algorithm is more efficient and accurate for damage detection problems in general. This implies that the proposed method is applicable and effective in the community of damage detection and structural health monitoring.

Fatigue Damage Estimation and Data-based Control for Wind Turbines

DEFF Research Database (Denmark)

Barradas Berglind, Jose de Jesus; Wisniewski, Rafal; Soltani, Mohsen

2015-01-01

based on hysteresis operators, which can be used in control loops. The authors propose a data-based model predictive control (MPC) strategy that incorporates an online fatigue estimation method through the objective function, where the ultimate goal in mind is to reduce the fatigue damage of the wind......The focus of this work is on fatigue estimation and data-based controller design for wind turbines. The main purpose is to include a model of the fatigue damage of the wind turbine components in the controller design and synthesis process. This study addresses an online fatigue estimation method...... turbine components. The outcome is an adaptive or self-tuning MPC strategy for wind turbine fatigue damage reduction, which relies on parameter identification on previous measurement data. The results of the proposed strategy are compared with a baseline model predictive controller....

Biometric and Emotion Identification: An ECG Compression Based Method.

Science.gov (United States)

Brás, Susana; Ferreira, Jacqueline H T; Soares, Sandra C; Pinho, Armando J

2018-01-01

We present an innovative and robust solution to both biometric and emotion identification using the electrocardiogram (ECG). The ECG represents the electrical signal that comes from the contraction of the heart muscles, indirectly representing the flow of blood inside the heart, it is known to convey a key that allows biometric identification. Moreover, due to its relationship with the nervous system, it also varies as a function of the emotional state. The use of information-theoretic data models, associated with data compression algorithms, allowed to effectively compare ECG records and infer the person identity, as well as emotional state at the time of data collection. The proposed method does not require ECG wave delineation or alignment, which reduces preprocessing error. The method is divided into three steps: (1) conversion of the real-valued ECG record into a symbolic time-series, using a quantization process; (2) conditional compression of the symbolic representation of the ECG, using the symbolic ECG records stored in the database as reference; (3) identification of the ECG record class, using a 1-NN (nearest neighbor) classifier. We obtained over 98% of accuracy in biometric identification, whereas in emotion recognition we attained over 90%. Therefore, the method adequately identify the person, and his/her emotion. Also, the proposed method is flexible and may be adapted to different problems, by the alteration of the templates for training the model.

Primary Identification Methods and their Effectiveness in Mass Disaster Situations: A Literature Review

Directory of Open Access Journals (Sweden)

Naiara M. Gaglietti

2017-06-01

Full Text Available Mass disasters generally result in an elevated number of casualties that need identification. The primary identification methods listed by INTERPOL (DNA, fingerprint and forensic dentistry have a very important role in helping and speeding up the victim identification process. The present study sought to report mass destruction cases found in the literature published from 2005 to 2015 that have used the primary human identification methods. This study has been done as a literature review using the keywords: disasters, natural disasters, disaster victims, and human identification in a total of 16 selected papers and 13 listed disasters. It has been concluded that the primary identification methods are capable and efficient to perform a safe and satisfactory identification of mass disasters victims, used both separately or in combination.

Fungal Diversity in Field Mold-Damaged Soybean Fruits and Pathogenicity Identification Based on High-Throughput rDNA Sequencing

Directory of Open Access Journals (Sweden)

Jiang Liu

2017-05-01

Full Text Available Continuous rain and an abnormally wet climate during harvest can easily lead to soybean plants being damaged by field mold (FM, which can reduce seed yield and quality. However, to date, the underlying pathogen and its resistance mechanism have remained unclear. The objective of the present study was to investigate the fungal diversity of various soybean varieties and to identify and confirm the FM pathogenic fungi. A total of 62,382 fungal ITS1 sequences clustered into 164 operational taxonomic units (OTUs with 97% sequence similarity; 69 taxa were recovered from the samples by internal transcribed spacer (ITS region sequencing. The fungal community compositions differed among the tested soybeans, with 42 OTUs being amplified from all varieties. The quadratic relationships between fungal diversity and organ-specific mildew indexes were analyzed, confirming that mildew on soybean pods can mitigate FM damage to the seeds. In addition, four potentially pathogenic fungi were isolated from FM-damaged soybean fruits; morphological and molecular identification confirmed these fungi as Aspergillus flavus, A. niger, Fusarium moniliforme, and Penicillium chrysogenum. Further re-inoculation experiments demonstrated that F. moniliforme is dominant among these FM pathogenic fungi. These results lay the foundation for future studies on mitigating or preventing FM damage to soybean.

A review of damage detection methods for wind turbine blades

International Nuclear Information System (INIS)

Li, Dongsheng; Song, Gangbing; Ren, Liang; Li, Hongnan; Ho, Siu-Chun M

2015-01-01

Wind energy is one of the most important renewable energy sources and many countries are predicted to increase wind energy portion of their whole national energy supply to about twenty percent in the next decade. One potential obstacle in the use of wind turbines to harvest wind energy is the maintenance of the wind turbine blades. The blades are a crucial and costly part of a wind turbine and over their service life can suffer from factors such as material degradation and fatigue, which can limit their effectiveness and safety. Thus, the ability to detect damage in wind turbine blades is of great significance for planning maintenance and continued operation of the wind turbine. This paper presents a review of recent research and development in the field of damage detection for wind turbine blades. Specifically, this paper reviews frequently employed sensors including fiber optic and piezoelectric sensors, and four promising damage detection methods, namely, transmittance function, wave propagation, impedance and vibration based methods. As a note towards the future development trend for wind turbine sensing systems, the necessity for wireless sensing and energy harvesting is briefly presented. Finally, existing problems and promising research efforts for online damage detection of turbine blades are discussed. (topical review)

Creep/fatigue damage prediction of fast reactor components using shakedown methods

International Nuclear Information System (INIS)

Buckthorpe, D.E.

1997-01-01

The present status of the shakedown method is reviewed, the application of the shakedown based principles to complex hardening and creep behaviour is described and justified and the prediction of damage against design criteria outlined. Comparisons are made with full inelastic analysis solutions where these are available and against damage assessments using elastic and inelastic design code methods. Current and future developments of the method are described including a summary of the advances made in the development of the post process ADAPT, which has enabled the method to be applied to complex geometry features and loading cases. The paper includes a review of applications of the method to typical Fast Reactor structural example cases within the primary and secondary circuits. For the primary circuit this includes structures such as the large diameter internal shells which are surrounded by hot sodium and subject to slow and rapid thermal transient loadings. One specific case is the damage assessment associated with thermal stratifications within sodium and the effects of moving sodium surfaces arising from reactor trip conditions. Other structures covered are geometric features within components such as the Above Core structure and Intermediate Heat Exchanger. For the secondary circuit the method has been applied to alternative and more complex forms of geometry namely thick section tubeplates of the Steam Generator and a typical secondary circuit piping run. Both of these applications are in an early stage of development but are expected to show significant advantages with respect to creep and fatigue damage estimation compared with existing code methods. The principle application of the method to design has so far been focused on Austenitic Stainless steel components however current work shows some significant benefits may be possible from the application of the method to structures made from Ferritic steels such as Modified 9Cr 1Mo. This aspect is briefly

A topological method for vortex identification in turbulent flows

Energy Technology Data Exchange (ETDEWEB)

Zhong, Qiang; Chen, Huai; Li, Danxun [State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084 (China); Chen, Qigang, E-mail: lidx@mail.tsinghua.edu.cn [School of Civil Engineering, Beijing Jiaotong University, Beijing 100044 (China)

2017-02-15

We present a novel vortex identification method based on structured vorticity ( ω {sub s}) of the direction field of flow (velocity vectors set to unit magnitude). As a direct measure of streamline curvature is insensitive to vortex strength, ω {sub s} is effective in detecting vortices of various strengths. The effectiveness has been tested against both analytical flows (pure shear flow, Oseen vortex flow, strong outward spiraling motion, straining flow, Taylor–Green flow) and experimental flows (closed cavity flow, closed and open channel flow). Comparison of the new method with the swirling-strength method indicates that the new method shows promise as being a simple and effective criterion for vortex identification. (paper)

Damage detection in composite panels based on mode-converted Lamb waves sensed using 3D laser scanning vibrometer

Science.gov (United States)

Pieczonka, Łukasz; Ambroziński, Łukasz; Staszewski, Wiesław J.; Barnoncel, David; Pérès, Patrick

2017-12-01

This paper introduces damage identification approach based on guided ultrasonic waves and 3D laser Doppler vibrometry. The method is based on the fact that the symmetric and antisymmetric Lamb wave modes differ in amplitude of the in-plane and out-of-plane vibrations. Moreover, the modes differ also in group velocities and normally they are well separated in time. For a given time window both modes can occur simultaneously only close to the wave source or to a defect that leads to mode conversion. By making the comparison between the in-plane and out-of-plane wave vector components the detection of mode conversion is possible, allowing for superior and reliable damage detection. Experimental verification of the proposed damage identification procedure is performed on fuel tank elements of Reusable Launch Vehicles designed for space exploration. Lamb waves are excited using low-profile, surface-bonded piezoceramic transducers and 3D scanning laser Doppler vibrometer is used to characterize the Lamb wave propagation field. The paper presents theoretical background of the proposed damage identification technique as well as experimental arrangements and results.

A Comparison of Vibration and Oil Debris Gear Damage Detection Methods Applied to Pitting Damage

Science.gov (United States)

Dempsey, Paula J.

2000-01-01

Helicopter Health Usage Monitoring Systems (HUMS) must provide reliable, real-time performance monitoring of helicopter operating parameters to prevent damage of flight critical components. Helicopter transmission diagnostics are an important part of a helicopter HUMS. In order to improve the reliability of transmission diagnostics, many researchers propose combining two technologies, vibration and oil monitoring, using data fusion and intelligent systems. Some benefits of combining multiple sensors to make decisions include improved detection capabilities and increased probability the event is detected. However, if the sensors are inaccurate, or the features extracted from the sensors are poor predictors of transmission health, integration of these sensors will decrease the accuracy of damage prediction. For this reason, one must verify the individual integrity of vibration and oil analysis methods prior to integrating the two technologies. This research focuses on comparing the capability of two vibration algorithms, FM4 and NA4, and a commercially available on-line oil debris monitor to detect pitting damage on spur gears in the NASA Glenn Research Center Spur Gear Fatigue Test Rig. Results from this research indicate that the rate of change of debris mass measured by the oil debris monitor is comparable to the vibration algorithms in detecting gear pitting damage.

Damage Detection Method of Wind Turbine Blade Using Acoustic Emission Signal Mapping

Energy Technology Data Exchange (ETDEWEB)

Han, Byeong Hee; Yoon, Dong JIn [Korea Research Institute of Standards and Seience, Daejeon (Korea, Republic of)

2011-02-15

Acoustic emission(AE) has emerged as a powerful nondestructive tool to detect any further growth or expansion of preexisting defects or to characterize failure mechanisms. Recently, this kind of technique, that is an in-situ monitoring of inside damages of materials or structures, becomes increasingly popular for monitoring the integrity of large structures like a huge wind turbine blade. Therefore, it is required to find a symptom of damage propagation before catastrophic failure through a continuous monitoring. In this study, a new damage location method has been proposed by using signal napping algorithm, and an experimental verification is conducted by using small wind turbine blade specimen: a part of 750 kW real blade. The results show that this new signal mapping method has high advantages such as a flexibility for sensor location, improved accuracy, high detectability. The newly proposed method was compared with traditional AE source location method based on arrival time difference

The Detection of Subsynchronous Oscillation in HVDC Based on the Stochastic Subspace Identification Method

Directory of Open Access Journals (Sweden)

Chen Shi

2014-01-01

Full Text Available Subsynchronous oscillation (SSO usually caused by series compensation, power system stabilizer (PSS, high voltage direct current transmission (HVDC and other power electronic equipment, which will affect the safe operation of generator shafting even the system. It is very important to identify the modal parameters of SSO to take effective control strategies as well. Since the identification accuracy of traditional methods are not high enough, the stochastic subspace identification (SSI method is proposed to improve the identification accuracy of subsynchronous oscillation modal. The stochastic subspace identification method was compared with the other two methods on subsynchronous oscillation IEEE benchmark model and Xiang-Shang HVDC system model, the simulation results show that the stochastic subspace identification method has the advantages of high identification precision, high operation efficiency and strong ability of anti-noise.

Earthquake Building Damage Mapping Based on Feature Analyzing Method from Synthetic Aperture Radar Data

Science.gov (United States)

An, L.; Zhang, J.; Gong, L.

2018-04-01

Playing an important role in gathering information of social infrastructure damage, Synthetic Aperture Radar (SAR) remote sensing is a useful tool for monitoring earthquake disasters. With the wide application of this technique, a standard method, comparing post-seismic to pre-seismic data, become common. However, multi-temporal SAR processes, are not always achievable. To develop a post-seismic data only method for building damage detection, is of great importance. In this paper, the authors are now initiating experimental investigation to establish an object-based feature analysing classification method for building damage recognition.

Biometric and Emotion Identification: An ECG Compression Based Method

Directory of Open Access Journals (Sweden)

Susana Brás

2018-04-01

Full Text Available We present an innovative and robust solution to both biometric and emotion identification using the electrocardiogram (ECG. The ECG represents the electrical signal that comes from the contraction of the heart muscles, indirectly representing the flow of blood inside the heart, it is known to convey a key that allows biometric identification. Moreover, due to its relationship with the nervous system, it also varies as a function of the emotional state. The use of information-theoretic data models, associated with data compression algorithms, allowed to effectively compare ECG records and infer the person identity, as well as emotional state at the time of data collection. The proposed method does not require ECG wave delineation or alignment, which reduces preprocessing error. The method is divided into three steps: (1 conversion of the real-valued ECG record into a symbolic time-series, using a quantization process; (2 conditional compression of the symbolic representation of the ECG, using the symbolic ECG records stored in the database as reference; (3 identification of the ECG record class, using a 1-NN (nearest neighbor classifier. We obtained over 98% of accuracy in biometric identification, whereas in emotion recognition we attained over 90%. Therefore, the method adequately identify the person, and his/her emotion. Also, the proposed method is flexible and may be adapted to different problems, by the alteration of the templates for training the model.

Biometric and Emotion Identification: An ECG Compression Based Method

Science.gov (United States)

Brás, Susana; Ferreira, Jacqueline H. T.; Soares, Sandra C.; Pinho, Armando J.

2018-01-01

We present an innovative and robust solution to both biometric and emotion identification using the electrocardiogram (ECG). The ECG represents the electrical signal that comes from the contraction of the heart muscles, indirectly representing the flow of blood inside the heart, it is known to convey a key that allows biometric identification. Moreover, due to its relationship with the nervous system, it also varies as a function of the emotional state. The use of information-theoretic data models, associated with data compression algorithms, allowed to effectively compare ECG records and infer the person identity, as well as emotional state at the time of data collection. The proposed method does not require ECG wave delineation or alignment, which reduces preprocessing error. The method is divided into three steps: (1) conversion of the real-valued ECG record into a symbolic time-series, using a quantization process; (2) conditional compression of the symbolic representation of the ECG, using the symbolic ECG records stored in the database as reference; (3) identification of the ECG record class, using a 1-NN (nearest neighbor) classifier. We obtained over 98% of accuracy in biometric identification, whereas in emotion recognition we attained over 90%. Therefore, the method adequately identify the person, and his/her emotion. Also, the proposed method is flexible and may be adapted to different problems, by the alteration of the templates for training the model. PMID:29670564

Damage detection in high-rise buildings using damage-induced rotations

International Nuclear Information System (INIS)

Sung, Seung Hun; Jung, Ho Youn; Lee, Jung Hoon; Jung, Hyung Jo

2016-01-01

In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not

Damage detection in high-rise buildings using damage-induced rotations

International Nuclear Information System (INIS)

Sung, Seung Hoon; Jung, Ho Youn; Lee, Jung Hoon; Jung, Hyung Jo

2014-01-01

In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not.

Rapid screening of guar gum using portable Raman spectral identification methods.

Science.gov (United States)

Srivastava, Hirsch K; Wolfgang, Steven; Rodriguez, Jason D

2016-01-25

Guar gum is a well-known inactive ingredient (excipient) used in a variety of oral pharmaceutical dosage forms as a thickener and stabilizer of suspensions and as a binder of powders. It is also widely used as a food ingredient in which case alternatives with similar properties, including chemically similar gums, are readily available. Recent supply shortages and price fluctuations have caused guar gum to come under increasing scrutiny for possible adulteration by substitution of cheaper alternatives. One way that the U.S. FDA is attempting to screen pharmaceutical ingredients at risk for adulteration or substitution is through field-deployable spectroscopic screening. Here we report a comprehensive approach to evaluate two field-deployable Raman methods--spectral correlation and principal component analysis--to differentiate guar gum from other gums. We report a comparison of the sensitivity of the spectroscopic screening methods with current compendial identification tests. The ability of the spectroscopic methods to perform unambiguous identification of guar gum compared to other gums makes them an enhanced surveillance alternative to the current compendial identification tests, which are largely subjective in nature. Our findings indicate that Raman spectral identification methods perform better than compendial identification methods and are able to distinguish guar gum from other gums with 100% accuracy for samples tested by spectral correlation and principal component analysis. Published by Elsevier B.V.

An novel identification method of the environmental risk sources for surface water pollution accidents in chemical industrial parks.

Science.gov (United States)

Peng, Jianfeng; Song, Yonghui; Yuan, Peng; Xiao, Shuhu; Han, Lu

2013-07-01

The chemical industry is a major source of various pollution accidents. Improving the management level of risk sources for pollution accidents has become an urgent demand for most industrialized countries. In pollution accidents, the released chemicals harm the receptors to some extent depending on their sensitivity or susceptibility. Therefore, identifying the potential risk sources from such a large number of chemical enterprises has become pressingly urgent. Based on the simulation of the whole accident process, a novel and expandable identification method for risk sources causing water pollution accidents is presented. The newly developed approach, by analyzing and stimulating the whole process of a pollution accident between sources and receptors, can be applied to identify risk sources, especially on the nationwide scale. Three major types of losses, such as social, economic and ecological losses, were normalized, analyzed and used for overall consequence modeling. A specific case study area, located in a chemical industry park (CIP) along the Yangtze River in Jiangsu Province, China, was selected to test the potential of the identification method. The results showed that there were four risk sources for pollution accidents in this CIP. Aniline leakage in the HS Chemical Plant would lead to the most serious impact on the surrounding water environment. This potential accident would severely damage the ecosystem up to 3.8 km downstream of Yangtze River, and lead to pollution over a distance stretching to 73.7 km downstream. The proposed method is easily extended to the nationwide identification of potential risk sources.

Quantitative evaluation for small surface damage based on iterative difference and triangulation of 3D point cloud

Science.gov (United States)

Zhang, Yuyan; Guo, Quanli; Wang, Zhenchun; Yang, Degong

2018-03-01

This paper proposes a non-contact, non-destructive evaluation method for the surface damage of high-speed sliding electrical contact rails. The proposed method establishes a model of damage identification and calculation. A laser scanning system is built to obtain the 3D point cloud data of the rail surface. In order to extract the damage region of the rail surface, the 3D point cloud data are processed using iterative difference, nearest neighbours search and a data registration algorithm. The curvature of the point cloud data in the damage region is mapped to RGB color information, which can directly reflect the change trend of the curvature of the point cloud data in the damage region. The extracted damage region is divided into three prism elements by a method of triangulation. The volume and mass of a single element are calculated by the method of geometric segmentation. Finally, the total volume and mass of the damage region are obtained by the principle of superposition. The proposed method is applied to several typical injuries and the results are discussed. The experimental results show that the algorithm can identify damage shapes and calculate damage mass with milligram precision, which are useful for evaluating the damage in a further research stage.

An Identification Key for Selecting Methods for Sustainability Assessments

Directory of Open Access Journals (Sweden)

Michiel C. Zijp

2015-03-01

Full Text Available Sustainability assessments can play an important role in decision making. This role starts with selecting appropriate methods for a given situation. We observed that scientists, consultants, and decision-makers often do not systematically perform a problem analyses that guides the choice of the method, partly related to a lack of systematic, though sufficiently versatile approaches to do so. Therefore, we developed and propose a new step towards method selection on the basis of question articulation: the Sustainability Assessment Identification Key. The identification key was designed to lead its user through all important choices needed for comprehensive question articulation. Subsequently, methods that fit the resulting specific questions are suggested by the key. The key consists of five domains, of which three determine method selection and two the design or use of the method. Each domain consists of four or more criteria that need specification. For example in the domain “system boundaries”, amongst others, the spatial and temporal scales are specified. The key was tested (retrospectively on a set of thirty case studies. Using the key appeared to contribute to improved: (i transparency in the link between the question and method selection; (ii consistency between questions asked and answers provided; and (iii internal consistency in methodological design. There is latitude to develop the current initial key further, not only for selecting methods pertinent to a problem definition, but also as a principle for associated opportunities such as stakeholder identification.

Optimum Identification Method of Sorting Green Household Waste

Directory of Open Access Journals (Sweden)

Daud Mohd Hisam

2016-01-01

Full Text Available This project is related to design of sorting facility for reducing, reusing, recycling green waste material, and in particular to invent an automatic system to distinguish household waste in order to separate them from the main waste stream. The project focuses on thorough analysis of the properties of green household waste. The method of identification is using capacitive sensor where the characteristic data taken on three different sensor drive frequency. Three types of material have been chosen as a medium of this research, to be separated using the selected method. Based on capacitance characteristics and its ability to penetrate green object, optimum identification method is expected to be recognized in this project. The output capacitance sensor is in analogue value. The results demonstrate that the information from the sensor is enough to recognize the materials that have been selected.

Characterizing microbial diversity and damage in mural paintings.

Science.gov (United States)

Rosado, Tânia; Mirão, José; Candeias, António; Caldeira, Ana Teresa

2015-02-01

Mural paintings are some of the oldest and most important cultural expressions of mankind and play an important role for the understanding of societies and civilizations. These cultural assets have high economic and cultural value and therefore their degradation has social and economic impact. The present work presents a novel microanalytical approach to understand the damages caused by microbial communities in mural paintings. This comprises the characterization and identification of microbial diversity and evaluation of damage promoted by their biological activity. Culture-dependent methods and DNA-based approaches like denaturing gradient gel electrophoresis (DGGE) and pyrosequencing are important tools in the isolation and identification of the microbial communities allowing characterization of the biota involved in the biodeterioration phenomena. Raman microspectrometry, infrared spectrometry, and variable pressure scanning electron microscopy coupled with energy-dispersive X-ray spectrometry are also useful tools for evaluation of the presence of microbial contamination and detection of the alteration products resulting from metabolic activity of the microorganisms. This study shows that the degradation status of mural paintings can be correlated to the presence of metabolically active microorganisms.

An alkaline separation method for detection of small amount of DNA damage

International Nuclear Information System (INIS)

Sakai, Kazuo; Okada, Shigefumi

1981-01-01

An alkaline separation technique originally established by Ahnstroem is modified to detect small amount of DNA damage in X-irradiated mouse leukemic L5178Y cells. It is made quantitative by calibration with an alkaline sucrose gradient centrifugation. The present method would make it possible to study DNA damage and its repair within a dose range of X-rays where cell survival and mutation are usually investigated. It is also useful for detecting DNA damage caused by chemicals. (author)

Computational botany methods for automated species identification

CERN Document Server

Remagnino, Paolo; Wilkin, Paul; Cope, James; Kirkup, Don

2017-01-01

This book discusses innovative methods for mining information from images of plants, especially leaves, and highlights the diagnostic features that can be implemented in fully automatic systems for identifying plant species. Adopting a multidisciplinary approach, it explores the problem of plant species identification, covering both the concepts of taxonomy and morphology. It then provides an overview of morphometrics, including the historical background and the main steps in the morphometric analysis of leaves together with a number of applications. The core of the book focuses on novel diagnostic methods for plant species identification developed from a computer scientist’s perspective. It then concludes with a chapter on the characterization of botanists' visions, which highlights important cognitive aspects that can be implemented in a computer system to more accurately replicate the human expert’s fixation process. The book not only represents an authoritative guide to advanced computational tools fo...

A damage detection method for instrumented civil structures using prerecorded Green’s functions and cross-correlation

OpenAIRE

Heckman, Vanessa; Kohler, Monica; Heaton, Thomas

2011-01-01

Automated damage detection methods have application to instrumented structures that are susceptible to types of damage that are difficult or costly to detect. The presented method has application to the detection of brittle fracture of welded beam-column connections in steel moment-resisting frames (MRFs), where locations of potential structural damage are known a priori. The method makes use of a prerecorded catalog of Green’s function templates and a cross-correlation method ...

Radionuclide identification using subtractive clustering method

International Nuclear Information System (INIS)

Farias, Marcos Santana; Mourelle, Luiza de Macedo

2011-01-01

Radionuclide identification is crucial to planning protective measures in emergency situations. This paper presents the application of a method for a classification system of radioactive elements with a fast and efficient response. To achieve this goal is proposed the application of subtractive clustering algorithm. The proposed application can be implemented in reconfigurable hardware, a flexible medium to implement digital hardware circuits. (author)

Analysis of factors influencing fire damage to concrete using nonlinear resonance vibration method

Energy Technology Data Exchange (ETDEWEB)

Park, Gang Kyu; Park, Sun Jong; Kwak, Hyo Gyoung [Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, KAIST, Daejeon (Korea, Republic of); Yim, Hong Jae [Dept. of Construction and Disaster Prevention Engineering, Kyungpook National University, Sangju (Korea, Republic of)

2015-04-15

In this study, the effects of different mix proportions and fire scenarios (exposure temperatures and post-fire-curing periods) on fire-damaged concrete were analyzed using a nonlinear resonance vibration method based on nonlinear acoustics. The hysteretic nonlinearity parameter was obtained, which can sensitively reflect the damage level of fire-damaged concrete. In addition, a splitting tensile strength test was performed on each fire-damaged specimen to evaluate the residual property. Using the results, a prediction model for estimating the residual strength of fire-damaged concrete was proposed on the basis of the correlation between the hysteretic nonlinearity parameter and the ratio of splitting tensile strength.

A method for the estimation of the probability of damage due to earthquakes

International Nuclear Information System (INIS)

Alderson, M.A.H.G.

1979-07-01

The available information on seismicity within the United Kingdom has been combined with building damage data from the United States to produce a method of estimating the probability of damage to structures due to the occurrence of earthquakes. The analysis has been based on the use of site intensity as the major damage producing parameter. Data for structural, pipework and equipment items have been assumed and the overall probability of damage calculated as a function of the design level. Due account is taken of the uncertainties of the seismic data. (author)

A Bayesian statistical method for particle identification in shower counters

International Nuclear Information System (INIS)

Takashimizu, N.; Kimura, A.; Shibata, A.; Sasaki, T.

2004-01-01

We report an attempt on identifying particles using a Bayesian statistical method. We have developed the mathematical model and software for this purpose. We tried to identify electrons and charged pions in shower counters using this method. We designed an ideal shower counter and studied the efficiency of identification using Monte Carlo simulation based on Geant4. Without having any other information, e.g. charges of particles which are given by tracking detectors, we have achieved 95% identifications of both particles

Damage detection in composites using nonlinear ultrasonically modulated thermography

Science.gov (United States)

Malfense Fierro, G.-P.; Dionysopoulos, D.; Meo, M.; Ciampa, F.

2018-03-01

This paper proposes a novel nonlinear ultrasonically stimulated thermography technique for a quick and reliable assessment of material damage in carbon fibre reinforced plastic (CFRP) composite materials. The proposed nondestructive evaluation (NDE) method requires narrow sweep ultrasonic excitation using contact piezoelectric transducers in order to identify dual excitation frequencies associated with the damage resonance. High-amplitude signals and higher harmonic generation are necessary conditions for an accurate identification of these two input frequencies. Dual periodic excitation using high- and low-frequency input signals was then performed in order to generate frictional heating at the crack location that was measured by an infrared (IR) camera. To validate this concept, an impact damaged CFRP composite panel was tested and the experimental results were compared with traditional flash thermography. A laser vibrometer was used to investigate the response of the material with dual frequency excitation. The proposed nonlinear ultrasonically modulated thermography successfully detected barely visible impact damage in CFRP composites. Hence, it can be considered as an alternative to traditional flash thermography and thermosonics by allowing repeatable detection of damage in composites.

Identification of Damage in IR-Structures from Earthquake Records - Optimal Location of Sensors

DEFF Research Database (Denmark)

Nielsen, Søren R.K.; Skjærbæk, P. S.; Cakmak, A. S.

A method for localization of structural damage is seismically excited RC-structures using measured acceleration response time series is presented. from measured response from some or all storeys, the two lowest smoothed eigenfrequencies and mode shape coordinates are estimated. these estimates ar...

Assessment of damage domains of the High-Temperature Engineering Test Reactor (HTTR)

International Nuclear Information System (INIS)

Flores, Alain; Izquierdo, José María; Tuček, Kamil; Gallego, Eduardo

2014-01-01

Highlights: • We developed an adequate model for the identification of damage domains of the HTTR. • We analysed an anticipated operational transient, using the HTTR5+/GASTEMP code. • We simulated several transients of the same sequence. • We identified the corresponding damage domains using two methods. • We calculated exceedance frequency using the two methods. - Abstract: This paper presents an assessment analysis of damage domains of the 30 MW th prototype High-Temperature Engineering Test Reactor (HTTR) operated by the Japan Atomic Energy Agency (JAEA). For this purpose, an in-house deterministic risk assessment computational tool was developed based on the Theory of Stimulated Dynamics (TSD). To illustrate the methodology and applicability of the developed modelling approach, assessment results of a control rod (CR) withdrawal accident during subcritical conditions are presented and compared with those obtained by the JAEA

Particle identification methods in High Energy Physics

Energy Technology Data Exchange (ETDEWEB)

Va' Vra, J.

2000-01-27

This paper deals with two major particle identification methods: dE/dx and Cherenkov detection. In the first method, the authors systematically compare existing dE/dx data with various predictions available in the literature, such as the Particle Data group recommendation, and judge the overall consistency. To my knowledge, such comparison was not done yet in a published form for the gaseous detectors used in High-Energy physics. As far as the second method, there are two major Cherenkov light detection techniques: the threshold and the Ring imaging methods. The authors discuss the recent trend in these techniques.

Nondestructive damage detection and evaluation technique for seismically damaged structures

Science.gov (United States)

Adachi, Yukio; Unjoh, Shigeki; Kondoh, Masuo; Ohsumi, Michio

1999-02-01

The development of quantitative damage detection and evaluation technique, and damage detection technique for invisible damages of structures are required according to the lessons from the 1995 Hyogo-ken Nanbu earthquake. In this study, two quantitative damage sensing techniques for highway bridge structures are proposed. One method is to measure the change of vibration characteristics of the bridge structure. According to the damage detection test for damaged bridge column by shaking table test, this method can successfully detect the vibration characteristic change caused by damage progress due to increment excitations. The other method is to use self-diagnosis intelligent materials. According to the reinforced concrete beam specimen test, the second method can detect the damage by rupture of intelligent sensors, such as optical fiber or carbon fiber reinforced plastic rod.

An Improved Spectral Analysis Method for Fatigue Damage Assessment of Details in Liquid Cargo Tanks

Science.gov (United States)

Zhao, Peng-yuan; Huang, Xiao-ping

2018-03-01

Errors will be caused in calculating the fatigue damages of details in liquid cargo tanks by using the traditional spectral analysis method which is based on linear system, for the nonlinear relationship between the dynamic stress and the ship acceleration. An improved spectral analysis method for the assessment of the fatigue damage in detail of a liquid cargo tank is proposed in this paper. Based on assumptions that the wave process can be simulated by summing the sinusoidal waves in different frequencies and the stress process can be simulated by summing the stress processes induced by these sinusoidal waves, the stress power spectral density (PSD) is calculated by expanding the stress processes induced by the sinusoidal waves into Fourier series and adding the amplitudes of each harmonic component with the same frequency. This analysis method can take the nonlinear relationship into consideration and the fatigue damage is then calculated based on the PSD of stress. Take an independent tank in an LNG carrier for example, the accuracy of the improved spectral analysis method is proved much better than that of the traditional spectral analysis method by comparing the calculated damage results with the results calculated by the time domain method. The proposed spectral analysis method is more accurate in calculating the fatigue damages in detail of ship liquid cargo tanks.

Damage identification of RC bridge decks under fatigue loading

Directory of Open Access Journals (Sweden)

Zanuy, C.

2014-12-01

Full Text Available The complex nature of structural phenomena still requires the comparison between numerical models and the real structural performance. Accordingly, many civil structures are monitored to detect structural damage and provide updated data for numerical models. Monitoring usually relies on the change of dynamic properties (experimental modal analysis. Regarding concrete structures, existing works have typically focused on the progressive decrease of natural frequencies under gradually increasing loads. In this paper, high-cycle fatigue effects are analyzed. An experimental campaign on specimens reproducing the top slab of concrete girders has been carried out, including fatigue tests and a reference static test. Impact-excitation tests were done at different stages to extract dynamic properties. Output-only models (only based on the structural response to an external excitation that is not measured were used as identification techniques. The evolution of dynamic properties was correlated with damage development, with emphasis on the fatigue process stages: crack formation, cyclic reduction of tension-stiffening and brittle fracture of the reinforcement.La naturaleza compleja de muchos fenómenos estructurales requiere que los modelos numéricos necesiten ser verificados con el comportamiento estructural real. Por ello, muchas estructuras son monitorizadas, tanto para detectar posibles daños estructurales como para proporcionar datos a incluir en los modelos. A menudo, la monitorización se basa en el cambio de las propiedades dinámicas mediante técnicas de análisis modal experimental. Con respecto al hormigón estructural, la mayoría de los trabajos existentes se ha centrado en el cambio de las frecuencias propias con cargas monótonamente crecientes. En este artículo se analizan los efectos de la fatiga. Se ha llevado a cabo una campaña experimental sobre piezas que reproducen la losa superior de tableros de puentes, realizándose ensayos

Damage to buds and shoots of coniferous woody plants

DEFF Research Database (Denmark)

Witzell, J.; Matsiakh, I.; Poljakovic Pajnik, L.

2017-01-01

to provide a tentative identification of relatively broad groups of organisms and not definitive identification of the causal agents. Hence, the pictures in this guide need to be regarded as typical examples of the described symptoms. There are chapters that explain how to use the guide, followed by keys...... (for different organs of conifer and broadleaf species) to guide the user to the relevant sections of the book, based on the questions entomologists and pathologists ask themselves when looking at a damaged or diseased tree in a fashion similar to how a doctor interrogates a patient to arrive...... at a diagnosis. The largest part of the book is devoted to the description and illustration of damage types and typical causes of the observed damage. The last chapters provide instructions for taking and preserving samples for further identification by an expert, notification of relevant authorities...

Nuclear material enrichment identification method based on cross-correlation and high order spectra

International Nuclear Information System (INIS)

Yang Fan; Wei Biao; Feng Peng; Mi Deling; Ren Yong

2013-01-01

In order to enhance the sensitivity of nuclear material identification system (NMIS) against the change of nuclear material enrichment, the principle of high order statistic feature is introduced and applied to traditional NMIS. We present a new enrichment identification method based on cross-correlation and high order spectrum algorithm. By applying the identification method to NMIS, the 3D graphs with nuclear material character are presented and can be used as new signatures to identify the enrichment of nuclear materials. The simulation result shows that the identification method could suppress the background noises, electronic system noises, and improve the sensitivity against enrichment change to exponential order with no system structure modification. (authors)

Development of evaluation method for software hazard identification techniques

International Nuclear Information System (INIS)

Huang, H. W.; Chen, M. H.; Shih, C.; Yih, S.; Kuo, C. T.; Wang, L. H.; Yu, Y. C.; Chen, C. W.

2006-01-01

This research evaluated the applicable software hazard identification techniques nowadays, such as, Preliminary Hazard Analysis (PHA), Failure Modes and Effects Analysis (FMEA), Fault Tree Analysis (FTA), Markov chain modeling, Dynamic Flow-graph Methodology (DFM), and simulation-based model analysis; and then determined indexes in view of their characteristics, which include dynamic capability, completeness, achievability, detail, signal/noise ratio, complexity, and implementation cost. By this proposed method, the analysts can evaluate various software hazard identification combinations for specific purpose. According to the case study results, the traditional PHA + FMEA + FTA (with failure rate) + Markov chain modeling (with transfer rate) combination is not competitive due to the dilemma for obtaining acceptable software failure rates. However, the systematic architecture of FTA and Markov chain modeling is still valuable for realizing the software fault structure. The system centric techniques, such as DFM and simulation-based model-analysis, show the advantage on dynamic capability, achievability, detail, signal/noise ratio. However, their disadvantages are the completeness complexity and implementation cost. This evaluation method can be a platform to reach common consensus for the stakeholders. Following the evolution of software hazard identification techniques, the evaluation results could be changed. However, the insight of software hazard identification techniques is much more important than the numbers obtained by the evaluation. (authors)

Nondestructive Damage Assessment of Composite Structures Based on Wavelet Analysis of Modal Curvatures: State-of-the-Art Review and Description of Wavelet-Based Damage Assessment Benchmark

Directory of Open Access Journals (Sweden)

Andrzej Katunin

2015-01-01

Full Text Available The application of composite structures as elements of machines and vehicles working under various operational conditions causes degradation and occurrence of damage. Considering that composites are often used for responsible elements, for example, parts of aircrafts and other vehicles, it is extremely important to maintain them properly and detect, localize, and identify the damage occurring during their operation in possible early stage of its development. From a great variety of nondestructive testing methods developed to date, the vibration-based methods seem to be ones of the least expensive and simultaneously effective with appropriate processing of measurement data. Over the last decades a great popularity of vibration-based structural testing has been gained by wavelet analysis due to its high sensitivity to a damage. This paper presents an overview of results of numerous researchers working in the area of vibration-based damage assessment supported by the wavelet analysis and the detailed description of the Wavelet-based Structural Damage Assessment (WavStructDamAs Benchmark, which summarizes the author’s 5-year research in this area. The benchmark covers example problems of damage identification in various composite structures with various damage types using numerous wavelet transforms and supporting tools. The benchmark is openly available and allows performing the analysis on the example problems as well as on its own problems using available analysis tools.

Micromechanical modeling and inverse identification of damage using cohesive approaches

International Nuclear Information System (INIS)

Blal, Nawfal

2013-01-01

In this study a micromechanical model is proposed for a collection of cohesive zone models embedded between two each elements of a standard cohesive-volumetric finite element method. An equivalent 'matrix-inclusions' composite is proposed as a representation of the cohesive-volumetric discretization. The overall behaviour is obtained using homogenization approaches (Hashin Shtrikman scheme and the P. Ponte Castaneda approach). The derived model deals with elastic, brittle and ductile materials. It is available whatever the triaxiality loading rate and the shape of the cohesive law, and leads to direct relationships between the overall material properties and the local cohesive parameters and the mesh density. First, rigorous bounds on the normal and tangential cohesive stiffnesses are obtained leading to a suitable control of the inherent artificial elastic loss induced by intrinsic cohesive models. Second, theoretical criteria on damageable and ductile cohesive parameters are established (cohesive peak stress, critical separation, cohesive failure energy,... ). These criteria allow a practical calibration of the cohesive zone parameters as function of the overall material properties and the mesh length. The main interest of such calibration is its promising capacity to lead to a mesh-insensitive overall response in surface damage. (author) [fr

Fuel number identification method and device therefor

International Nuclear Information System (INIS)

Doi, Takami; Seno, Makoto; Tanaka, Keiji

1998-01-01

The present invention provides a method of and a device for automatically identifying the number on the upper surface of a fuel of a fuel assembly in a PWR type reactor. Namely, the number on the upper surface of the fuel assembly of the PWR is not arranged in a row, but indent letters are dispersed to predetermined positions of the surface to be indented. Accordingly, the identification of letters is difficult. In the present invention, the letters are identified by the following procedures. Procedure (1): the letters are detected while having a corner portion of the upper surface of a fuel assembly where the number is indented as characteristic points. A procedure (2): a letter region is determined to a relative position based on the characteristic points while determining indent letters having the same direction as one group. A procedure (3): a letter identification treatment is applied to the letter images in the above-mentioned letter region to identify them. A neural network is used for the letter identification treatment. (N.H.)

Comparison of PCR method with the culture method for identification of gonococci from endocervical swabs

Directory of Open Access Journals (Sweden)

Alam A

2002-01-01

Full Text Available Gonococcal infection remains still a major cause of morbidity among sexually active individuals. Diagnosis of the infection in a female case is more difficult than that in a male. This was a prospective study among 269 female commercial sex workers (CSWs to screen them for gonococcal infection, comparing the rapid method of identification of gonococci by polymerase chain reaction (PCR with the selective culture method. A total of 92 (34.2% CSWs were identified positive for Neisseria gonorrhoeae by combination of the two methods. The PCR method identified 87 of the specimens to harbour cppB gene of N. gonorrhoeae, whereas culture method identified 83 specimens showing colonies of gonococci. Taking into consideration of the total positive cases (92, the PCR method showed a sensitivity of 94.57%, whereas sensitivity of culture method was 90.22%. The selective culture method appears to be the most applicable in the identification of gonococci from clinical specimens, particularly in the less resourceful countries like Bangladesh.

Methods of Identification and Evaluation of Brownfield Sites

Directory of Open Access Journals (Sweden)

Safet Kurtović

2014-04-01

Full Text Available The basic objective of this paper was to determine the importance and potential restoration of brownfield sites in terms of economic prosperity of a particular region or country. In addition, in a theoretical sense, this paper presents the methods used in the identification of brownfield sites such as Smart Growth Network model and Thomas GIS model, and methods for evaluation of brownfield sites or the indexing method, cost-benefit and multivariate analysis.

FRF-based structural damage detection of controlled buildings with podium structures: Experimental investigation

Science.gov (United States)

Xu, Y. L.; Huang, Q.; Zhan, S.; Su, Z. Q.; Liu, H. J.

2014-06-01

How to use control devices to enhance system identification and damage detection in relation to a structure that requires both vibration control and structural health monitoring is an interesting yet practical topic. In this study, the possibility of using the added stiffness provided by control devices and frequency response functions (FRFs) to detect damage in a building complex was explored experimentally. Scale models of a 12-storey main building and a 3-storey podium structure were built to represent a building complex. Given that the connection between the main building and the podium structure is most susceptible to damage, damage to the building complex was experimentally simulated by changing the connection stiffness. To simulate the added stiffness provided by a semi-active friction damper, a steel circular ring was designed and used to add the related stiffness to the building complex. By varying the connection stiffness using an eccentric wheel excitation system and by adding or not adding the circular ring, eight cases were investigated and eight sets of FRFs were measured. The experimental results were used to detect damage (changes in connection stiffness) using a recently proposed FRF-based damage detection method. The experimental results showed that the FRF-based damage detection method could satisfactorily locate and quantify damage.

Vibration based structural health monitoring in fibre reinforced composites employing the modal strain energy method

NARCIS (Netherlands)

Loendersloot, Richard; Ooijevaar, T.H.; Warnet, Laurent; Akkerman, Remko; de Boer, Andries; Meguid, S.A.; Gomes, J.F.S.

2009-01-01

The feasibility of a vibration based damage identification method is investigated. The Modal Strain Energy method is applied to a T–beam structure. The dynamic response of an intact structure and a damaged, delaminated structure is analysed employing a commercially available Finite Element package.

Moving force identification based on modified preconditioned conjugate gradient method

Science.gov (United States)

Chen, Zhen; Chan, Tommy H. T.; Nguyen, Andy

2018-06-01

This paper develops a modified preconditioned conjugate gradient (M-PCG) method for moving force identification (MFI) by improving the conjugate gradient (CG) and preconditioned conjugate gradient (PCG) methods with a modified Gram-Schmidt algorithm. The method aims to obtain more accurate and more efficient identification results from the responses of bridge deck caused by vehicles passing by, which are known to be sensitive to ill-posed problems that exist in the inverse problem. A simply supported beam model with biaxial time-varying forces is used to generate numerical simulations with various analysis scenarios to assess the effectiveness of the method. Evaluation results show that regularization matrix L and number of iterations j are very important influence factors to identification accuracy and noise immunity of M-PCG. Compared with the conventional counterpart SVD embedded in the time domain method (TDM) and the standard form of CG, the M-PCG with proper regularization matrix has many advantages such as better adaptability and more robust to ill-posed problems. More importantly, it is shown that the average optimal numbers of iterations of M-PCG can be reduced by more than 70% compared with PCG and this apparently makes M-PCG a preferred choice for field MFI applications.

Identification Damage Model for Thermomechanical Degradation of Ductile Heterogeneous Materials

Science.gov (United States)

Amri, A. El; Yakhloufi, M. H. El; Khamlichi, A.

2017-05-01

The failure of ductile materials subject to high thermal and mechanical loading rates is notably affected by material inertia. The mechanisms of fatigue-crack propagation are examined with particular emphasis on the similarities and differences between cyclic crack growth in ductile materials, such as metals, and corresponding behavior in brittle materials, such as intermetallic and ceramics. Numerical simulations of crack propagation in a cylindrical specimen demonstrate that the proposed method provides an effective means to simulate ductile fracture in large scale cylindrical structures with engineering accuracy. The influence of damage on the intensity of the destruction of materials is studied as well.

Developing Dynamic Digital Image Correlation Technique to Monitor Structural Damage of Old Buildings under External Excitation

Directory of Open Access Journals (Sweden)

Ming-Hsiang Shih

2014-01-01

Full Text Available The capacity of buildings to resist external excitation is an important factor to consider for the structural design of buildings. When subject to external excitation, a building may suffer a certain degree of damages, and its residual capacity to resist external excitation cannot be evaluated. In this research, dynamic digital image correlation method combined with parameter evaluation available in system identification is used to evaluate the structural capacity to resist external excitation. The results reveal possible building latent safety problems so that timely structural reinforcement or dismantling of the building can be initiated to alleviate further damages. The results of experiments using the proposed method conform to the results obtained using the conventional method, but this method is more convenient and rapid than the latter in the subsequent procedure of data processing. If only the frequency change is used, the damages suffered by the building can be detected, but the damage location is not revealed. The interstory drift mode shape (IDMS based on the characteristic of story drift has higher sensitivity than the approximate story damage index (ADSI method based on modal frequency and vibration type; however, both indices can be used to determine the degree and location of building damages.

A Systematic Identification Method for Thermodynamic Property Modelling

DEFF Research Database (Denmark)

Ana Perederic, Olivia; Cunico, Larissa; Sarup, Bent

2017-01-01

In this work, a systematic identification method for thermodynamic property modelling is proposed. The aim of the method is to improve the quality of phase equilibria prediction by group contribution based property prediction models. The method is applied to lipid systems where the Original UNIFAC...... model is used. Using the proposed method for estimating the interaction parameters using only VLE data, a better phase equilibria prediction for both VLE and SLE was obtained. The results were validated and compared with the original model performance...

A new coupled elastoplastic damage model for clay-stone and its parameter identification

International Nuclear Information System (INIS)

Jia, S.P.; Chen, W.Z.; Yu, H.D.; Li, X.L.; Sillen, X.

2010-01-01

into two zones according to peak stress point. The damage of material has obvious effect on the elastic stiffness, yielding function, potential function and hardening / softening variables. The assumption for the constitutive model of Boom Clay is as follows: 1) The residual deformation is very small in the zone before peak stress, and the stress-strain curve is nonlinear. The elastic damage model is applied to describe the mechanical behavior before peak stress. 2) The stain softens after the stress reach peak strength, and the Mohr-Coulomb criterion is applied to describe the mechanical behaviour during the course of the damage. 3) The residual stress state also can be described by the Mohr-Coulomb criterion. Furthermore, damage evolution equation is suggested based on the defined damage potential. Based on the implicit Euler integration algorithm, UMAT subroutine of the constitutive model is implemented in the finite element program ABAQUS. A methodology of back analysis combining the Nelder-Mead algorithm and finite element method together with ABAQUS is proposed. Then, a new exact penalty function is constructed between the monitored data and numerical results. The back analysis program for 3-D constitutive model is programmed in Matlab. According to undrained triaxial consolidation tests of Boom clay under different confining pressure, the parameters in constitutive model are obtained by back analysis method. The comparison between numerical results and experimental results shows that the new developed model can fit the experimental results very well in the frame of elasto-plastic damage model. So, the proposed model is able to effectively depict the main features of mechanical behaviors of Boom clay. The presented model can provide references for the distribution, degree and evolution of damage of excavated disturbed zone and fractures self-sealing process analysis of surrounding rock. (authors)

Individual feature identification method for nuclear accident emergency decision-making

International Nuclear Information System (INIS)

Chen Yingfeng; Wang Jianlong; Lin Xiaoling; Yang Yongxin; Lu Xincheng

2014-01-01

According to the individual feature identification method and combining with the characteristics of nuclear accident emergency decision-making, the evaluation index system of the nuclear accident emergency decision-making was determined on the basis of investigation and analysis. The effectiveness of the nuclear accident emergency decision-making was evaluated based on the individual standards by solving the individual features of the individual standard identification decisions. The case study shows that the optimization result is reasonable, objective and reliable, and it can provide an effective analysis method and decision-making support for optimization of nuclear accident emergency protective measures. (authors)

Detection of damage in welded structure using experimental modal data

Energy Technology Data Exchange (ETDEWEB)

Abu Husain, N [Transportation Research Alliance, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Ouyang, H, E-mail: nurul@fkm.utm.my, E-mail: h.ouyang@liv.ac.uk [Department of Engineering, Harrison-Hughes Building, University of Liverpool, Brownlow Hill, Liverpool L69 3GH (United Kingdom)

2011-07-19

A typical automotive structure could contain thousands of spot weld joints that contribute significantly to the vehicle's structural stiffness and dynamic characteristics. However, some of these joints may be imperfect or even absent during the manufacturing process and they are also highly susceptible to damage due to operational and environmental conditions during the vehicle lifetime. Therefore, early detection and estimation of damage are important so necessary actions can be taken to avoid further problems. Changes in physical parameters due to existence of damage in a structure often leads to alteration of vibration modes; thus demonstrating the dependency between the vibration characteristics and the physical properties of structures. A sensitivity-based model updating method, performed using a combination of MATLAB and NASTRAN, has been selected for the purpose of this work. The updating procedure is regarded as parameter identification which aims to bring the numerical prediction to be as closely as possible to the measured natural frequencies and mode shapes data of the damaged structure in order to identify the damage parameters (characterised by the reductions in the Young's modulus of the weld patches to indicate the loss of material/stiffness at the damage region).

Benchmarking Discount Rate in Natural Resource Damage Assessment with Risk Aversion.

Science.gov (United States)

Wu, Desheng; Chen, Shuzhen

2017-08-01

Benchmarking a credible discount rate is of crucial importance in natural resource damage assessment (NRDA) and restoration evaluation. This article integrates a holistic framework of NRDA with prevailing low discount rate theory, and proposes a discount rate benchmarking decision support system based on service-specific risk aversion. The proposed approach has the flexibility of choosing appropriate discount rates for gauging long-term services, as opposed to decisions based simply on duration. It improves injury identification in NRDA since potential damages and side-effects to ecosystem services are revealed within the service-specific framework. A real embankment case study demonstrates valid implementation of the method. © 2017 Society for Risk Analysis.

Identification Male Fertility Through Abnormalities Sperm Based Morphology (Teratospermia) using Invariant Moment Method

Science.gov (United States)

Syahputra, M. F.; Chairani, R.; Seniman; Rahmat, R. F.; Abdullah, D.; Napitupulu, D.; Setiawan, M. I.; Albra, W.; Erliana, C. I.; Andayani, U.

2018-03-01

Sperm morphology is still a standard laboratory analysis in diagnosing infertility in men. Manually identification of sperm form is still not accurate, the difficulty in seeing the form of the invisible sperm from the digital microscope image is often a weakness in the process of identification and takes a long time. Therefore, male fertility identification application system is needed Through sperm abnormalities based on sperm morphology (teratospermia). The method used is invariant moment method. This study uses 15 data testing and 20 data training sperm image. That the process of male fertility identification through sperm abnormalities based on sperm morphology (teratospermia) has an accuracy rate of 80.77%. Use of time to process Identification of male fertility through sperm abnormalities Based on sperm morphology (teratospermia) during 0.4369 seconds.

Impact Damage Evaluation Method of Friction Disc Based on High-Speed Photography and Tooth-Root Stress Coupling

International Nuclear Information System (INIS)

Yin, L; Shao, Y M; Liu, J; Zheng, H L

2015-01-01

The stability of friction disc could be seriously affected by the tooth surface damage due to poor working conditions of the wet multi-disc brake in heavy trucks. There are few current works focused on the damage of the friction disc caused by torsion-vibration impacts. Hence, it is necessary to investigate its damage mechanisms and evaluation methods. In this paper, a damage mechanism description and evaluation method of a friction disc based on the high-speed photography and tooth-root stress coupling is proposed. According to the HighSpeed Photography, the collision process between the friction disc and hub is recorded, which can be used to determine the contact position and deformation. Combined with the strain-stress data obtained by the strain gauge at the place of the tooth-root, the impact force and property are studied. In order to obtain the evaluation method, the damage surface morphology data of the friction disc extracted by 3D Super Depth Digital Microscope (VH-Z100R) is compared with the impact force and property. The quantitative relationships between the amount of deformation and collision number are obtained using a fitting analysis method. The experimental results show that the damage of the friction disc can be evaluated by the proposed impact damage evaluation method based on the high-speed photography and tooth-root stress coupling. (paper)

An inverse method for the identification of a distributed random excitation acting on a vibrating structure. Theory

International Nuclear Information System (INIS)

Granger, S.; Perotin, L.

1997-01-01

Maintaining the PWR components under reliable operating conditions requires a complex design to prevent various damaging processes, including fatigue and wear problems due to flow-induced vibration. In many practical situations, it is difficult, if not impossible, to perform direct measurements or calculations of the external forces acting on vibrating structures. Instead, vibrational responses can often be conveniently measured. This paper presents an inverse method for estimating a distributed random excitation from the measurement of the structural response at a number of discrete points. This paper is devoted to the presentation of the theoretical development. The force identification method is based on a modal model for the structure and a spatial orthonormal decomposition of the excitation field. The estimation of the Fourier coefficients of this orthonormal expansion is presented. As this problem turns out to be ill-posed, a regularization process is introduced. The minimization problem associated to this process is then formulated and its solutions is developed. (author)

A system boundary identification method for life cycle assessment

DEFF Research Database (Denmark)

Li, Tao; Zhang, Hongchao; Liu, Zhichao

2014-01-01

, technical, geographical and temporal dimensions are presented to limit the boundaries of LCA. An algorithm is developed to identify an appropriate boundary by searching the process tree and evaluating the environmental impact contribution of each process while it is added into the studied system...... as processes are added. The two threshold rules and identification methods presented can be used to identify system boundary of LCA. The case study demonstrated that the methodology presented in this paper is an effective tool for the boundary identification....

COMPARATIVE ANALYSIS OF METHODS FOR IDENTIFICATION OF NONTUBERCULOUS MYCOBACTERIA ISOLATED FROM CLINICAL MATERIAL

Directory of Open Access Journals (Sweden)

A. V. Lyamin

2017-01-01

Full Text Available Recently there has been a significant increase in the incidence of mycobacteriosis, which is due to an increase in the proportion of immunosuppressed patients, the presence of these various comorbid conditions, as well as the improvement of diagnostic methods. Selecting the most accurate method of identification is extremely important in determining treatment strategy of patients. The aim of the study was to conduct a comparative analysis of modern methods of identification NTMB isolated from clinical specimens in 2015 in the Samara region. The work was carried out identification of 78 strains of microorganisms. Laboratory diagnosis was carried out using the DNA hybridization method and MALDI-ToF mass spectrometry. When microbial identification using MALDI-ToF mass spectrometry was isolated 16 strains (20.5% M. kansasii; 11 strains (14.1% M. avium and M. fortuitum; 9 strains (11.5% M. gordonae; strain 3 (3.8% M. peregrinum, M. szulgai, M. chimera intracellulare group, strain 2 (2.6% M. abscessus, M. septicum, M. paragordonae, M. senegalence, 1 strain (1.3% M. chelonae, M. frederiksbergense, M. monacense, M. lentiflavum. By using mass spectrometry, it was identified 15 types NTMB compared with 9 types — by DNA hybridization. Full match identification results was observed only in 45 (57.7% strains of divergent strains were found in 16 (20.5%. Most often when using the DNA hybridization method, discrepancy was detected in slow-growing cultures (9 strains with a predominance of microorganisms identified as M. gordonae. Among the representatives of fast-growing NTMB, seven investigations were identified in the identification, more often among representatives of the M. fortuitum and M. peregrinum groups. Particular attention should be paid to the identification of the M. kansasii strain by a molecular genetic method, which mass spectrometry was defined as M. bovis. Both cultures of M. tuberculosis complex, which were identified by MALDI

Ion bombardment induced damage in silicon carbide studied by ion beam analytical methods

Energy Technology Data Exchange (ETDEWEB)

Szilagyi, E.; Kotai, E. [Magyar Tudomanyos Akademia, Budapest (HU). Research Inst. for Particle and Nuclear Physics (RIPNP); Khanh, N.Q.; Horvath, Z.E.; Lohner, T.; Battistig, G.; Zolnai, Z.; Gyulai, J. [Research Inst. for Technical Physics and Materials Science, Budapest (Hungary)

2001-07-01

Damage created by implantation of Al{sup +} ions into 4H-SiC is characterized using backscattering spectrometry in combination with channeling. The measurability of the damage profile in the carbon sublattice was demonstrated using the 4260 keV {sup 12}C({alpha},{alpha}){sup 12}C resonance. To create disorder, Al{sup +} ions with energy of 200 keV and 350 keV were implanted at room temperature. As an independent method, cross-sectional transmission electron microscopy was used to study the damage structure in irradiated 4H-SiC. (orig.)

[Combine fats products: methodic opportunities of it identification].

Science.gov (United States)

Viktorova, E V; Kulakova, S N; Mikhaĭlov, N A

2006-01-01

At present time very topical problem is falsification of milk fat. The number of methods was considered to detection of milk fat authention and possibilities his difference from combined fat products. The analysis of modern approaches to valuation of milk fat authention has showed that the main method for detection of fat nature is gas chromatography analysis. The computer method of express identification of fat products is proposed for quick getting of information about accessory of examine fat to nature milk or combined fat product.

Large deviations and queueing networks: Methods for rate function identification

OpenAIRE

Atar, Rami; Dupuis, Paul

1999-01-01

This paper considers the problem of rate function identification for multidimensional queueing models with feedback. A set of techniques are introduced which allow this identification when the model possesses certain structural properties. The main tools used are representation formulas for exponential integrals, weak convergence methods, and the regularity properties of associated Skorokhod Problems. Two examples are treated as special cases of the general theory: the classical Jackson netwo...

Identification system for chemical warfare agents with PGNAA method

International Nuclear Information System (INIS)

Wang Bairong; Yin Guanghua; Yang Zhongpin

2007-01-01

The principle and the experimental commanding of Chemical warfare Agents Identification with PGNAA method are discussed in this paper. The choosing of detector, neutron source and the data processing method are detailed. Finally, a set of experimental instruments composed of Cf-232 and BGO detector is developed based on this theory discussed above. (authors)

Scintigraphy for the detection of myocardial damage in the indeterminate form of Chagas disease

International Nuclear Information System (INIS)

Pedroso, Enio Roberto Pietra; Rezende, Nilton Alves de

2010-01-01

Background: non-invasive cardiological methods have been used for the identification of myocardial damage in Chagas disease. Objective: to verify whether the rest/stress myocardial perfusion scintigraphy is able to identify early myocardial damage in the indeterminate form of Chagas disease. Methods: eighteen patients with the indeterminate form of Chagas Disease and the same number of normal controls, paired by sex and age, underwent rest/stress myocardial scintigraphy using sestamibi-99mTc, aiming at detecting early cardiac damage. Results: the results did not show perfusion or ventricular function defects in patients at the indeterminate phase of Chagas disease and in the normal controls, except for a patient who presented signs of ventricular dysfunction in the myocardial perfusion scintigraphy with electrocardiographic gating. Conclusion: the results of this study, considering the small sample size, showed that the rest/stress myocardial scintigraphy using sestamibi-99mTc is not an effective method to detect early myocardial alterations in the indeterminate form of Chagas disease (author)

Scintigraphy for the detection of myocardial damage in the indeterminate form of Chagas disease

Energy Technology Data Exchange (ETDEWEB)

Pedroso, Enio Roberto Pietra; Rezende, Nilton Alves de, E-mail: narezende@terra.com.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Faculdade de Medicina; Abuhid, Ivana Moura [Instituto de Medicina Nuclear e Diagnostico Molecular, Belo Horizonte, MG (Brazil)

2010-07-15

Background: non-invasive cardiological methods have been used for the identification of myocardial damage in Chagas disease. Objective: to verify whether the rest/stress myocardial perfusion scintigraphy is able to identify early myocardial damage in the indeterminate form of Chagas disease. Methods: eighteen patients with the indeterminate form of Chagas Disease and the same number of normal controls, paired by sex and age, underwent rest/stress myocardial scintigraphy using sestamibi-99mTc, aiming at detecting early cardiac damage. Results: the results did not show perfusion or ventricular function defects in patients at the indeterminate phase of Chagas disease and in the normal controls, except for a patient who presented signs of ventricular dysfunction in the myocardial perfusion scintigraphy with electrocardiographic gating. Conclusion: the results of this study, considering the small sample size, showed that the rest/stress myocardial scintigraphy using sestamibi-99mTc is not an effective method to detect early myocardial alterations in the indeterminate form of Chagas disease (author)

The PLR-DTW method for ECG based biometric identification.

Science.gov (United States)

Shen, Jun; Bao, Shu-Di; Yang, Li-Cai; Li, Ye

2011-01-01

There has been a surge of research on electrocardiogram (ECG) signal based biometric for person identification. Though most of the existing studies claimed that ECG signal is unique to an individual and can be a viable biometric, one of the main difficulties for real-world applications of ECG biometric is the accuracy performance. To address this problem, this study proposes a PLR-DTW method for ECG biometric, where the Piecewise Linear Representation (PLR) is used to keep important information of an ECG signal segment while reduce the data dimension at the same time if necessary, and the Dynamic Time Warping (DTW) is used for similarity measures between two signal segments. The performance evaluation was carried out on three ECG databases, and the existing method using wavelet coefficients, which was proved to have good accuracy performance, was selected for comparison. The analysis results show that the PLR-DTW method achieves an accuracy rate of 100% for identification, while the one using wavelet coefficients achieved only around 93%.

Libraries for spectrum identification: Method of normalized coordinates versus linear correlation

International Nuclear Information System (INIS)

Ferrero, A.; Lucena, P.; Herrera, R.G.; Dona, A.; Fernandez-Reyes, R.; Laserna, J.J.

2008-01-01

In this work it is proposed that an easy solution based directly on linear algebra in order to obtain the relation between a spectrum and a spectrum base. This solution is based on the algebraic determination of an unknown spectrum coordinates with respect to a spectral library base. The identification capacity comparison between this algebraic method and the linear correlation method has been shown using experimental spectra of polymers. Unlike the linear correlation (where the presence of impurities may decrease the discrimination capacity), this method allows to detect quantitatively the existence of a mixture of several substances in a sample and, consequently, to beer in mind impurities for improving the identification

A model based bayesian solution for characterization of complex damage scenarios in aerospace composite structures.

Science.gov (United States)

Reed, H; Leckey, Cara A C; Dick, A; Harvey, G; Dobson, J

2018-01-01

Ultrasonic damage detection and characterization is commonly used in nondestructive evaluation (NDE) of aerospace composite components. In recent years there has been an increased development of guided wave based methods. In real materials and structures, these dispersive waves result in complicated behavior in the presence of complex damage scenarios. Model-based characterization methods utilize accurate three dimensional finite element models (FEMs) of guided wave interaction with realistic damage scenarios to aid in defect identification and classification. This work describes an inverse solution for realistic composite damage characterization by comparing the wavenumber-frequency spectra of experimental and simulated ultrasonic inspections. The composite laminate material properties are first verified through a Bayesian solution (Markov chain Monte Carlo), enabling uncertainty quantification surrounding the characterization. A study is undertaken to assess the efficacy of the proposed damage model and comparative metrics between the experimental and simulated output. The FEM is then parameterized with a damage model capable of describing the typical complex damage created by impact events in composites. The damage is characterized through a transdimensional Markov chain Monte Carlo solution, enabling a flexible damage model capable of adapting to the complex damage geometry investigated here. The posterior probability distributions of the individual delamination petals as well as the overall envelope of the damage site are determined. Copyright © 2017 Elsevier B.V. All rights reserved.

A steam generating unit identification using subspace methods

International Nuclear Information System (INIS)

Poshtan, J.; Mojallali, H.

2002-01-01

A Valid boiler model is a tool for the improvement of the steam generation control system and hence results boiler efficiency enhancement. However, methods of obtaining such a model are not readily found in the open literature and are often specific to a particular plant. This paper presents boiler model using a new method in system identification called S ubspace methods . This method is shown to provide an accurate state space model for boiler in a few numbers of operations, directly from input-output data without any prior knowledge of the system equations and any requirement to several stages of testing

A method for assessing frost damage risk in sweet cherry orchards of South Patagonia

NARCIS (Netherlands)

Cittadini, E.D.; Ridder, de N.; Peri, P.L.; Keulen, van H.

2006-01-01

Quantification of frost damage risk is important in planning the development of new orchard areas and for decision-making on design and installation of frost control systems. The objective of this study was to develop a comprehensive method to quantify frost damage risk in different sweet cherry

A Method of Fire Scenarios Identification in a Consolidated Fire Risk Analysis

International Nuclear Information System (INIS)

Lim, Ho Gon; Han, Sang Hoon; Yang, Joon Eon

2010-01-01

Conventional fire PSA consider only two cases of fire scenarios, that is one for fire without propagation and the other for single propagation to neighboring compartment. Recently, a consolidated fire risk analysis using single fault tree (FT) was developed. However, the fire scenario identification in the new method is similar to conventional fire analysis method. The present study develops a new method of fire scenario identification in a consolidated fire risk analysis method. An equation for fire propagation is developed to identify fire scenario and a mapping method of fire scenarios into internal event risk model is discussed. Finally, an algorithm for automatic program is suggested

A Method for Ship Collision Damage and Energy Absorption Analysis and its Validation

DEFF Research Database (Denmark)

Zhang, Shengming; Pedersen, Preben Terndrup

2016-01-01

-examine this method’s validity andaccuracy for ship collision damage analysis in shipdesign assessments by comprehensive validations withthe experimental results from the public domain. Twentyexperimental tests have been selected, analysed andcompared with the results calculated using the proposedmethod. It can......For design evaluation there is a need for a method whichis fast, practical and yet accurate enough to determine theabsorbed energy and collision damage extent in shipcollision analysis. The most well-known simplifiedempirical approach to collision analysis was madeprobably by Minorsky and its...... limitation is also wellrecognized.The authors have previously developedsimple expressions for the relation between the absorbedenergy and the damaged material volume which take intoaccount the structural arrangements, the materialproperties and the damage modes. The purpose of thepresent paper is to re...

[Identification of Dens Draconis and Os Draconis by XRD method].

Science.gov (United States)

Chen, Guang-Yun; Wu, Qi-Nan; Shen, Bei; Chen, Rong

2012-04-01

To establish an XRD method for evaluating the quality of Os Draconis and Dens Draconis and applying in judgement of the counterfeit. Dens Draconis, Os Draconis and the counterfeit of Os Draconis were analyzed by XRD. Their diffraction patterns were clustered analysis and evaluated their similarity degree. Established the analytical method of Dens Draconis and Os Draconis basing the features fingerprint information of the 10 common peaks by XRD pattern. Obtained the XRD pattern of the counterfeit of Os Draconis. The similarity degree of separate sources of Dens Draconis was high,while the similarity degree of separate sources of Os Draconis was significant different from each other. This method can be used for identification and evaluation of Os Draconis and Dens Draconis. It also can be used for identification the counterfeit of Os Draconis effectively.

[Personal identification with biometric and genetic methods].

Science.gov (United States)

Cabanis, Emmanuel-Alain; Le Gall, Jean-Yves; Ardaillou, Raymond

2007-11-01

The need for personal identification is growing in many avenues of society. To "identify" a person is to establish a link between his or her observed characteristics and those previously stored in a database. To "authenticate" is to decide whether or not someone is the person he or she claims to be. These two objectives can now be achieved by analysing biometric data and genetic prints. All biometric techniques proceed in several stages: acquisition of an image or physical parameters, encoding them with a mathematical model, comparing the results of this model with those contained in the database, and calculating the error risk. These techniques must be usable worldwide and must examine specific and permanent personal data. The most widely used are facial recognition, digital prints (flexion folds and dermatoglyphs, that offer the advantage of leaving marks), and the surface and texture of the iris. Other biometric techniques analyse behaviours such as walking, signing, typing, or speaking. Implanted radio-transmitters are another means of identification. All these systems are evaluated on the basis of the same parameters, namely the false rejection rate, the false acceptance rate, and the failure-to-enrol rate. The uses of biometrics are increasing and diversifying, and now include national and international identification systems, control of access to protected sites, criminal and victim identification, and transaction security. Genetic methods can identify individuals almost infallibly, based on short tandem repeats of 2-5 nucleotides, or microsatellites. The most recent kits analyze 11-16 independent autosomal markers. Mitochondrial DNA and Y chromosome DNA can also be analyzed. These genetic tests are currently used to identify suspected criminals or their victims from biological samples, and to establish paternity. Personal identification raises many ethical questions, however, such as when to create and how to use a database while preserving personal freedom

Reconstruction of structural damage based on reflection intensity spectra of fiber Bragg gratings

International Nuclear Information System (INIS)

Huang, Guojun; Wei, Changben; Chen, Shiyuan; Yang, Guowei

2014-01-01

We present an approach for structural damage reconstruction based on the reflection intensity spectra of fiber Bragg gratings (FBGs). Our approach incorporates the finite element method, transfer matrix (T-matrix), and genetic algorithm to solve the inverse photo-elastic problem of damage reconstruction, i.e. to identify the location, size, and shape of a defect. By introducing a parameterized characterization of the damage information, the inverse photo-elastic problem is reduced to an optimization problem, and a relevant computational scheme was developed. The scheme iteratively searches for the solution to the corresponding direct photo-elastic problem until the simulated and measured (or target) reflection intensity spectra of the FBGs near the defect coincide within a prescribed error. Proof-of-concept validations of our approach were performed numerically and experimentally using both holed and cracked plate samples as typical cases of plane-stress problems. The damage identifiability was simulated by changing the deployment of the FBG sensors, including the total number of sensors and their distance to the defect. Both the numerical and experimental results demonstrate that our approach is effective and promising. It provides us with a photo-elastic method for developing a remote, automatic damage-imaging technique that substantially improves damage identification for structural health monitoring. (paper)

Identification of fine-leaved species of genus Festuca by molecular methods

International Nuclear Information System (INIS)

Stukonis, V.; Armoniene, R.; Kemesyte, V.

2015-01-01

Festuca (L.) is a taxonomically complex genus of family Poaceae. The fine-leaved species of fescue are well adapted to grow in sandy and dry habitats, therefore, they can be used for establishment of lawns of minimal maintenance as well as recultivations of damaged soils. Breeding for the new varieties to meet these purposes requires reliable methods for identification of the species. The discrimination of fine-leaved fescue species based on morphological features is rather difficult, therefore reliable molecular marker would greatly facilitate it and eliminate the need to wait till floral organs are fully formed. Seven fine-leaved species of genus Festuca collected in Lithuania, namely, F. ovina, F. trachyphylla, F. polesica, F. psammophila, F. sabulosa, F. pseudovina and F. wolgensis were investigated at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry. The ISSR markers, seed storage proteins and isozymes were tested for their ability to distinguish between the fine-leaved species of the genus Festuca. Seed storage protein and ISSR fingerprint profiles could be used to distinguish between fine-leaved species of Festuca, except for closely related F. sabulosa and F. polesica species. Isozyme fingerprints did not contain sufficient number of species specific bands and were not feasible to discriminate between species. (author)

Damage detection and quantification using mode curvature variation on framed structures: analysis of the preliminary results

Science.gov (United States)

Iacovino, Chiara; Ditommaso, Rocco; Auletta, Gianluca; Ponzo, Felice C.

2017-04-01

Continuous monitoring based on vibrational identification methods is increasingly employed for the evaluation of the state of health of existing buildings after strong motion earthquake. Different damage identification methods are based on the variations of damage indices defined in terms modal (eigenfrequencies, mode shapes, and modal damping) and/or non-modal parameters. Most of simplified methods for structural health monitoring and damage detection are based on the evaluation of the dynamic characteristics evolution associated to the fundamental mode of vibration of a monitored structure. Aim of this work is the upgrade of an existing method for damage localization on framed structures during a moderate/destructive earthquake. The existing version of the method is based on the comparison of the geometric characteristics (with particular reference to the mode curvature) exhibited by the structures, related to fundamental mode of vibration, before and during an earthquake. The approach is based on the use of a nonlinear filter, the band-variable filter, based on the Stockwell Transform able to extract the nonlinear response of each mode of vibration. The new version of the method provides the possibility to quantify a possible damage occurred on the monitored structure linking the mode curvature variation with the maximum inter-story drift. This paper shows the preliminary results obtained from several simulations on nonlinear numerical models of reinforced concrete framed structures, designed for only gravity loads, without and with the presence of infill panels. Furthermore, a correlation between maximum mode curvature difference and maximum inter-story drift has been defined for the different numerical models in order to quantify the structural damage. Acknowledgements This study was partially funded by the Italian Department of Civil Protection within the project DPC-RELUIS 2016 - RS4 ''Seismic observatory of structures and health monitoring'' and by the

Identification and calibration of the structural model of historical masonry building damaged during the 2016 Italian earthquakes: The case study of Palazzo del Podestà in Montelupone

Science.gov (United States)

Catinari, Federico; Pierdicca, Alessio; Clementi, Francesco; Lenci, Stefano

2017-11-01

The results of an ambient-vibration based investigation conducted on the "Palazzo del Podesta" in Montelupone (Italy) is presented. The case study was damaged during the 20I6 Italian earthquakes that stroke the central part of the Italy. The assessment procedure includes full-scale ambient vibration testing, modal identification from ambient vibration responses, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. A very good match between theoretical and experimental modal parameters was reached and the model updating has been performed identifying some structural parameters.

[Age specific and individual psychological factors of post--traumatic stress (PTS) development of children with after-effects of physical damages indicating medical rehabilitation].

Science.gov (United States)

Пятакова, Галина В; Лебедева, Екатерина И; Потявина, Валерия В; Церфус, Диана Н

children and teenagers having received hard physical damages face a difficult life situation which includes events accompanied by feeling of intensive fear and helplessness. Every child's individual psychological features play an important role in coping with negative psychological after-effects of his/her physical trauma. learning PTS manifestations among children and teenagers with hard physical damages indicating medical rehabilitation. patients of the traumatological department of children's surgery clinic took part in the research: 31 preadolescent children and their parents, 45 teengaers and their parents. Physical damages were received by children clinic's patients in accidents and out of negligence. A survey containing clinical and historical method elements, medical documents; semi-structured interviews for identification of signs of children's post-traumatic stress, a survey for parents for identification of children's traumatic experience, colour matrices and J. Raven black-and-white matrices, S. Rosenzweig frustration tolerance methods (children's and adult version) were used as certain research methods. it was shown that intellectual productivity showings and stable ways of emotional reaction can act as individual psychological factos of PTS development. Age specifics of embeddedness of intellectual features and stable ways of emotional reaction to PTS symptoms development among children and teenagers with hard physical damages. the received results can be used as a base for developing specific approaches for psychological support of children and teenagers having the experience of physical damage and difficult medical rehabilitation.

Comparison of three methods for identification of pathogenic Neisseria species

Energy Technology Data Exchange (ETDEWEB)

Appelbaum, P.C.; Lawrence, R.B.

1979-05-01

A radiometric procedure was compared with the Minitek and Cystine Trypticase Agar sugar degradation methods for identification of 113 Neisseria species (58 Neisseria meningitidis, 51 Neisseria gonorrhoeae, 2 Neisseria lactamica, 2 Neisseria sicca). Identification of meningococci and gonoccoi was confirmed by agglutination and fluorescent antibody techniques, respectively. The Minitek method identified 97% of meningococci, 92% of gonococci, and 100% of other Neisseria after 4 h of incubation. The radiometric (Bactec) procedure identified 100% of gonococci and 100% of miscellaneous Neisseria after 3 h, but problems were encountered with meningococci: 45% of the later strains yielded index values for fructose between 20 and 28 (recommended negative cut-off point, less than 20), with strongly positive (greater than 100) glucose and maltose and negative o-nitrophenyl-beta-0-galactopyranoside reactions in all 58 strains. The Cystine Trypticase Agar method identified 91% of meningococci, ases.

Appreciation the damage of kidney function with RIA method

International Nuclear Information System (INIS)

Wang Haodan

1992-01-01

Using RIA method, the authors took 4 kinds of urine specimen from 100 normal persons which were taken in the morning 1 h after drinking voluntary and all- 24 h, and stored at 4 C deg and -30 C deg respectively, in order to detect the concentration of the urine protein Β 2 -MG, ALb, IgG and THP. The results are as follows: for 3-days-storage at 4 C deg and 2-weeks-storage at -30 C deg, P > 0.05; for the ALb, IgG and THP between voluntary urine and 24 h urine, α = 0.7565, 0.7865 and 0.7537 respectively; for Β 2 -MG, between the 1h-urine after drinking and voluntary urine, α = 0.7238. The urinary levels were measured of Β 2 -MG, ALb, IgG and THP with voluntary urine specimen in 177 cases of various types of nephropathy, urino-infection, and diabetic nephrosis, hypertesion-nephrosis, systemic lupus erythematosus. It is considered that the method of testing urine protein with voluntary urine specimen is not only accurate for collecting but also convenient for the patient. It is more accurate and sensitive than the traditional BUN and Cr for the appreciation of kidney function damage. And it gives a early stage index of kidney damage

An extended diffraction tomography method for quantifying structural damage using numerical Green's functions.

Science.gov (United States)

Chan, Eugene; Rose, L R Francis; Wang, Chun H

2015-05-01

Existing damage imaging algorithms for detecting and quantifying structural defects, particularly those based on diffraction tomography, assume far-field conditions for the scattered field data. This paper presents a major extension of diffraction tomography that can overcome this limitation and utilises a near-field multi-static data matrix as the input data. This new algorithm, which employs numerical solutions of the dynamic Green's functions, makes it possible to quantitatively image laminar damage even in complex structures for which the dynamic Green's functions are not available analytically. To validate this new method, the numerical Green's functions and the multi-static data matrix for laminar damage in flat and stiffened isotropic plates are first determined using finite element models. Next, these results are time-gated to remove boundary reflections, followed by discrete Fourier transform to obtain the amplitude and phase information for both the baseline (damage-free) and the scattered wave fields. Using these computationally generated results and experimental verification, it is shown that the new imaging algorithm is capable of accurately determining the damage geometry, size and severity for a variety of damage sizes and shapes, including multi-site damage. Some aspects of minimal sensors requirement pertinent to image quality and practical implementation are also briefly discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of Story-wise Shear Building Identification Method to Actual Ambient Vibration

Directory of Open Access Journals (Sweden)

Kohei eFujita

2015-02-01

Full Text Available A sophisticated and smart story stiffness System Identification (SI method for a shear building model is applied to a full-scale building frame subjected to micro-tremors. The advantageous and novel feature is that not only the modal parameters, such as natural frequencies and damping ratios, but also the physical model parameters, such as story stiffnesses and damping coefficients, can be identified using micro-tremors. While the building responses to earthquake ground motions are necessary in the previous SI method, it is shown in this paper that the micro-tremor measurements in a full-scale 5 story building frame can be used for identification within the same framework. The SI using micro-tremor measurements leads to the enhanced usability of the previously proposed story-wise shear building identification method. The degree of ARX models and cut-off frequencies of band-pass filter are determined to derive reliable results.

An immunological approach of sperm sexing and different methods for identification of X- and Y-chromosome bearing sperm

Directory of Open Access Journals (Sweden)

Shiv Kumar Yadav

2017-05-01

Full Text Available Separation of X- and Y-chromosome bearing sperm has been practiced for selection of desired sex of offspring to increase the profit in livestock industries. At present, fluorescence-activated cell sorter is the only successful method for separation of X- and Y-chromosome bearing sperm. This technology is based on the differences in DNA content between these two types of sperm and has been commercialized for bovine sperm. However, this technology still has problems in terms of high economic cost, sperm damage, and lower pregnancy rates compared to unsorted semen. Therefore, an inexpensive, convenient, and non-invasive approach for sperm sexing would be of benefit to agricultural sector. Within this perspective, immunological sperm sexing method is one of the attractive choices to separate X- and Y-chromosome bearing sperm. This article reviews the current knowledge about immunological approaches, viz., H-Y antigen, sex-specific antigens, and differentially expressed proteins for sperm sexing. Moreover, this review also highlighted the different methods for identification of X- and Y-sperm.

Identification of fractional order systems using modulating functions method

KAUST Repository

Liu, Dayan

2013-06-01

The modulating functions method has been used for the identification of linear and nonlinear systems. In this paper, we generalize this method to the on-line identification of fractional order systems based on the Riemann-Liouville fractional derivatives. First, a new fractional integration by parts formula involving the fractional derivative of a modulating function is given. Then, we apply this formula to a fractional order system, for which the fractional derivatives of the input and the output can be transferred into the ones of the modulating functions. By choosing a set of modulating functions, a linear system of algebraic equations is obtained. Hence, the unknown parameters of a fractional order system can be estimated by solving a linear system. Using this method, we do not need any initial values which are usually unknown and not equal to zero. Also we do not need to estimate the fractional derivatives of noisy output. Moreover, it is shown that the proposed estimators are robust against high frequency sinusoidal noises and the ones due to a class of stochastic processes. Finally, the efficiency and the stability of the proposed method is confirmed by some numerical simulations.

Impulse response identification with deterministic inputs using non-parametric methods

International Nuclear Information System (INIS)

Bhargava, U.K.; Kashyap, R.L.; Goodman, D.M.

1985-01-01

This paper addresses the problem of impulse response identification using non-parametric methods. Although the techniques developed herein apply to the truncated, untruncated, and the circulant models, we focus on the truncated model which is useful in certain applications. Two methods of impulse response identification will be presented. The first is based on the minimization of the C/sub L/ Statistic, which is an estimate of the mean-square prediction error; the second is a Bayesian approach. For both of these methods, we consider the effects of using both the identity matrix and the Laplacian matrix as weights on the energy in the impulse response. In addition, we present a method for estimating the effective length of the impulse response. Estimating the length is particularly important in the truncated case. Finally, we develop a method for estimating the noise variance at the output. Often, prior information on the noise variance is not available, and a good estimate is crucial to the success of estimating the impulse response with a nonparametric technique

Probability of identification (POI): a statistical model for the validation of qualitative botanical identification methods

Science.gov (United States)

A qualitative botanical identification method (BIM) is an analytical procedure which returns a binary result (1 = Identified, 0 = Not Identified). A BIM may be used by a buyer, manufacturer, or regulator to determine whether a botanical material being tested is the same as the target (desired) mate...

A Method for Ship Collision Damage and Energy Absorption Analysis and its Validation

DEFF Research Database (Denmark)

Zhang, Shengming; Pedersen, Preben Terndrup

2017-01-01

For design evaluation, there is a need for a method which is fast, practical and yet accurate enough to deter-mine the absorbed energy and collision damage extent in ship collision analysis. The most well-known sim-plified empirical approach to collision analysis was made probably by Minorsky......, and its limitation is alsowell-recognised. The authors have previously developed simple expressions for the relation between theabsorbed energy and the damaged material volume which take into account the structural arrangements,the material properties and the damage modes. The purpose of the present paper...... is to re-examine thismethod’s validity and accuracy for ship collision damage analysis in ship design assessments by compre-hensive validations with experimental results from the public domain. In total, 20 experimental tests havebeen selected, analysed and compared with the results calculated using...

Evaluating current automatic de-identification methods with Veteran’s health administration clinical documents

Directory of Open Access Journals (Sweden)

Ferrández Oscar

2012-07-01

Full Text Available Abstract Background The increased use and adoption of Electronic Health Records (EHR causes a tremendous growth in digital information useful for clinicians, researchers and many other operational purposes. However, this information is rich in Protected Health Information (PHI, which severely restricts its access and possible uses. A number of investigators have developed methods for automatically de-identifying EHR documents by removing PHI, as specified in the Health Insurance Portability and Accountability Act “Safe Harbor” method. This study focuses on the evaluation of existing automated text de-identification methods and tools, as applied to Veterans Health Administration (VHA clinical documents, to assess which methods perform better with each category of PHI found in our clinical notes; and when new methods are needed to improve performance. Methods We installed and evaluated five text de-identification systems “out-of-the-box” using a corpus of VHA clinical documents. The systems based on machine learning methods were trained with the 2006 i2b2 de-identification corpora and evaluated with our VHA corpus, and also evaluated with a ten-fold cross-validation experiment using our VHA corpus. We counted exact, partial, and fully contained matches with reference annotations, considering each PHI type separately, or only one unique ‘PHI’ category. Performance of the systems was assessed using recall (equivalent to sensitivity and precision (equivalent to positive predictive value metrics, as well as the F2-measure. Results Overall, systems based on rules and pattern matching achieved better recall, and precision was always better with systems based on machine learning approaches. The highest “out-of-the-box” F2-measure was 67% for partial matches; the best precision and recall were 95% and 78%, respectively. Finally, the ten-fold cross validation experiment allowed for an increase of the F2-measure to 79% with partial matches

Method for assessing damage to mitochondrial DNA caused by radiation and epichlorohydrin

International Nuclear Information System (INIS)

Singh, G.; Hauswirth, W.W.; Ross, W.E.; Neims, A.H.

1985-01-01

This paper describes a rapid and reliable method for quantification of damage to mitochondrial DNA (mtDNA), especially strand breaks. The degree of damage to mtDNA is assessed by the proportion of physical forms (i.e., supercoiled versus open-circular and linear forms) upon agarose gel electrophoresis, blotting, and visualization by hybridization with [ 32 P]mtDNA probes. The use of a radiolabeled probe is a crucial step in the procedure because it provides both a means to quantify by radioautography and to obtain the mtDNA specificity required to eliminate misinterpretation due to nuclear DNA contamination. To demonstrate the utility of this technique, X-irradiation and epichlorohydrin are shown to damage both isolated mtDNA and mtDNA in whole cells in a dose-dependent fashion

Damage evolution analysis of coal samples under cyclic loading based on single-link cluster method

Science.gov (United States)

Zhang, Zhibo; Wang, Enyuan; Li, Nan; Li, Xuelong; Wang, Xiaoran; Li, Zhonghui

2018-05-01

In this paper, the acoustic emission (AE) response of coal samples under cyclic loading is measured. The results show that there is good positive relation between AE parameters and stress. The AE signal of coal samples under cyclic loading exhibits an obvious Kaiser Effect. The single-link cluster (SLC) method is applied to analyze the spatial evolution characteristics of AE events and the damage evolution process of coal samples. It is found that a subset scale of the SLC structure becomes smaller and smaller when the number of cyclic loading increases, and there is a negative linear relationship between the subset scale and the degree of damage. The spatial correlation length ξ of an SLC structure is calculated. The results show that ξ fluctuates around a certain value from the second cyclic loading process to the fifth cyclic loading process, but spatial correlation length ξ clearly increases in the sixth loading process. Based on the criterion of microcrack density, the coal sample failure process is the transformation from small-scale damage to large-scale damage, which is the reason for changes in the spatial correlation length. Through a systematic analysis, the SLC method is an effective method to research the damage evolution process of coal samples under cyclic loading, and will provide important reference values for studying coal bursts.

LORD-Q: a long-run real-time PCR-based DNA-damage quantification method for nuclear and mitochondrial genome analysis

Science.gov (United States)

Lehle, Simon; Hildebrand, Dominic G.; Merz, Britta; Malak, Peter N.; Becker, Michael S.; Schmezer, Peter; Essmann, Frank; Schulze-Osthoff, Klaus; Rothfuss, Oliver

2014-01-01

DNA damage is tightly associated with various biological and pathological processes, such as aging and tumorigenesis. Although detection of DNA damage is attracting increasing attention, only a limited number of methods are available to quantify DNA lesions, and these techniques are tedious or only detect global DNA damage. In this study, we present a high-sensitivity long-run real-time PCR technique for DNA-damage quantification (LORD-Q) in both the mitochondrial and nuclear genome. While most conventional methods are of low-sensitivity or restricted to abundant mitochondrial DNA samples, we established a protocol that enables the accurate sequence-specific quantification of DNA damage in >3-kb probes for any mitochondrial or nuclear DNA sequence. In order to validate the sensitivity of this method, we compared LORD-Q with a previously published qPCR-based method and the standard single-cell gel electrophoresis assay, demonstrating a superior performance of LORD-Q. Exemplarily, we monitored induction of DNA damage and repair processes in human induced pluripotent stem cells and isogenic fibroblasts. Our results suggest that LORD-Q provides a sequence-specific and precise method to quantify DNA damage, thereby allowing the high-throughput assessment of DNA repair, genotoxicity screening and various other processes for a wide range of life science applications. PMID:24371283

Analysis of blind identification methods for estimation of kinetic parameters in dynamic medical imaging

Science.gov (United States)

Riabkov, Dmitri

Compartment modeling of dynamic medical image data implies that the concentration of the tracer over time in a particular region of the organ of interest is well-modeled as a convolution of the tissue response with the tracer concentration in the blood stream. The tissue response is different for different tissues while the blood input is assumed to be the same for different tissues. The kinetic parameters characterizing the tissue responses can be estimated by blind identification methods. These algorithms use the simultaneous measurements of concentration in separate regions of the organ; if the regions have different responses, the measurement of the blood input function may not be required. In this work it is shown that the blind identification problem has a unique solution for two-compartment model tissue response. For two-compartment model tissue responses in dynamic cardiac MRI imaging conditions with gadolinium-DTPA contrast agent, three blind identification algorithms are analyzed here to assess their utility: Eigenvector-based Algorithm for Multichannel Blind Deconvolution (EVAM), Cross Relations (CR), and Iterative Quadratic Maximum Likelihood (IQML). Comparisons of accuracy with conventional (not blind) identification techniques where the blood input is known are made as well. The statistical accuracies of estimation for the three methods are evaluated and compared for multiple parameter sets. The results show that the IQML method gives more accurate estimates than the other two blind identification methods. A proof is presented here that three-compartment model blind identification is not unique in the case of only two regions. It is shown that it is likely unique for the case of more than two regions, but this has not been proved analytically. For the three-compartment model the tissue responses in dynamic FDG PET imaging conditions are analyzed with the blind identification algorithms EVAM and Separable variables Least Squares (SLS). A method of

Seismic damage diagnosis of a masonry building using short-term damping measurements

Science.gov (United States)

Kouris, Leonidas Alexandros S.; Penna, Andrea; Magenes, Guido

2017-04-01

It is of considerable importance to perform dynamic identification and detect damage in existing structures. This paper describes a new and practical method for damage diagnosis of masonry buildings requiring minimum computational effort. The method is based on the relative variation of modal damping and validated against experimental data from a full scale two storey shake table test. The experiment involves a building subjected to uniaxial vibrations of progressively increasing intensity at the facilities of EUCENTRE laboratory (Pavia, Italy) up to a near collapse damage state. Five time-histories are applied scaling the Montenegro (1979) accelerogram. These strong motion tests are preceded by random vibration tests (RVT's) which are used to perform modal analysis. Two deterministic methods are applied: the single degree of freedom (SDOF) assumption together with the peak-picking method in the discrete frequency domain and the Eigen realisation algorithm with data correlations (ERA-DC) in the discrete time domain. Regarding the former procedure, some improvements are incorporated to locate rigorously the natural frequencies and estimate the modal damping. The progressive evolution of the modal damping is used as a key indicator to characterise damage on the building. Modal damping is connected to the structural mass and stiffness. A square integrated but only with two components expression for proportional (classical) damping is proposed to fit better with the experimental measurements of modal damping ratios. Using this Rayleigh order formulation the contribution of each of the damping components is evaluated. The stiffness component coefficient is proposed as an effective index to detect damage and quantify its intensity.

Hankel Matrix Correlation Function-Based Subspace Identification Method for UAV Servo System

Directory of Open Access Journals (Sweden)

Minghong She

2018-01-01

Full Text Available For the identification problem of closed-loop subspace model, we propose a zero space projection method based on the estimation of correlation function to fill the block Hankel matrix of identification model by combining the linear algebra with geometry. By using the same projection of related data in time offset set and LQ decomposition, the multiplication operation of projection is achieved and dynamics estimation of the unknown equipment system model is obtained. Consequently, we have solved the problem of biased estimation caused when the open-loop subspace identification algorithm is applied to the closed-loop identification. A simulation example is given to show the effectiveness of the proposed approach. In final, the practicability of the identification algorithm is verified by hardware test of UAV servo system in real environment.

The impact of parameter identification methods on drug therapy control in an intensive care unit

NARCIS (Netherlands)

Hann, C.E.; Chase, J.G.; Ypma, M.F.; Elfring, J.; Nor, N.H.M.; Lawrence, P.; Shaw, G.M.

2008-01-01

This paper investigates the impact of fast parameter identification methods, which do not require any forward simulations, on model-based glucose control, using retrospective data in the Christchurch Hospital Intensive Care Unit. The integral-based identification method has been previously

Condition Assessment for Wastewater Pipes: Method for Assessing Cracking and Surface Damage of Concrete Pipes

OpenAIRE

Hauge, Petter

2013-01-01

The objective of the Master Thesis has been to provide an improved method for condition assessment, which will give a better correlation between Condition class and actual Condition of concrete pipes with cracking and/or surface damages. Additionally improvement of the characterization of cracking (SR) and surface (KO) damages was a sub goal.Based on the findings described in my Thesis and my Specialization Project (Hauge 2012), I recommend that the Norwegian condition assessment method based...

A new identification method for energetic ion ΔE-E telescopes

International Nuclear Information System (INIS)

Martin, Cesar; Bronchalo, Enrique; Medina, Jose

2007-01-01

A new ion identification method for ΔE-E telescopes is presented. The method works by counting data points under ΔE(E) curves on ΔE-E diagrams. These curves are obtained by simulating the telescope response to a flux of energetic ions. The method is checked against three published methods applied to several experimental data sets

A new identification method for energetic ion {delta}E-E telescopes

Energy Technology Data Exchange (ETDEWEB)

Martin, Cesar [Departamento de Fisica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts, Universitaet zu Kiel, 24118 Kiel (Germany); Bronchalo, Enrique [Departamento de Fisica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Departamento de Fisica y Arquitectura de Computadores, Universidad Miguel Hernandez, Avda. Universidad s/n, 03202 Elche, Alicante (Spain)], E-mail: ebronchalo@umh.es; Medina, Jose [Departamento de Fisica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain)

2007-11-21

A new ion identification method for {delta}E-E telescopes is presented. The method works by counting data points under {delta}E(E) curves on {delta}E-E diagrams. These curves are obtained by simulating the telescope response to a flux of energetic ions. The method is checked against three published methods applied to several experimental data sets.

Identification of Structurally Damaged Areas in Airborne Oblique Images Using a Visual-Bag-of-Words Approach

Directory of Open Access Journals (Sweden)

Anand Vetrivel

2016-03-01

Full Text Available Automatic post-disaster mapping of building damage using remote sensing images is an important and time-critical element of disaster management. The characteristics of remote sensing images available immediately after the disaster are not certain, since they may vary in terms of capturing platform, sensor-view, image scale, and scene complexity. Therefore, a generalized method for damage detection that is impervious to the mentioned image characteristics is desirable. This study aims to develop a method to perform grid-level damage classification of remote sensing images by detecting the damage corresponding to debris, rubble piles, and heavy spalling within a defined grid, regardless of the aforementioned image characteristics. The Visual-Bag-of-Words (BoW is one of the most widely used and proven frameworks for image classification in the field of computer vision. The framework adopts a kind of feature representation strategy that has been shown to be more efficient for image classification—regardless of the scale and clutter—than conventional global feature representations. In this study supervised models using various radiometric descriptors (histogram of gradient orientations (HoG and Gabor wavelets and classifiers (SVM, Random Forests, and Adaboost were developed for damage classification based on both BoW and conventional global feature representations, and tested with four datasets. Those vary according to the aforementioned image characteristics. The BoW framework outperformed conventional global feature representation approaches in all scenarios (i.e., for all combinations of feature descriptors, classifiers, and datasets, and produced an average accuracy of approximately 90%. Particularly encouraging was an accuracy improvement by 14% (from 77% to 91% produced by BoW over global representation for the most complex dataset, which was used to test the generalization capability.

SLD Identification: A Survey of Methods Used by School Psychologists

Science.gov (United States)

Watson, Michael D., Jr.; Simon, Joan B.; Nunnley, Lenora

2016-01-01

IDEA 2004 opened the door for states, and in some cases districts, to choose among three different methods for identifying children with Specific Learning Disabilities (SLDs). This study provides an in-depth look at SLD identification practices in a state that allows school psychologists to use any of the three methods. Eighty-four school…

A identification system for chemical warfare agents with PGNAA method

International Nuclear Information System (INIS)

Wang Bairong; Yin Guanghua; Yang Zhongping

2006-01-01

The principle and the experimental commanding of Chemical warfare Agents Identification with PGNAA method are discussed in this paper. The choosing of Detector, neutron source and the data processing method are detailed. Finally, a set of experimental instruments composed of Cf-232 and BGO detector is developed based on the theory discussed above. (authors)

A Dissipation Gap Method for full-field measurement-based identification of elasto-plastic material parameters

KAUST Repository

Blaysat, Benoît

2012-05-18

Using enriched data such as displacement fields obtained from digital image correlation is a pathway to the local identification of material parameters. Up to now, most of the identification techniques for nonlinear models are based on Finite Element Updating Methods. This article explains how an appropriate use of the Dissipation Gap Method can help in this context and be an interesting alternative to these classical techniques. The Dissipation Gap Methods rely on the concept of error in dissipation that has been used mainly for the verification of finite element simulations. We provide here an original application of these founding developments to the identification of material parameters for nonlinear behaviors. The proposed technique and especially the main technical keypoint of building the admissible fields are described in detail. The approach is then illustrated through the identification of heterogeneous isotropic elasto-plastic properties. The basic numerical features highlighted through these simple examples demonstrate this approach to be a promising tool for nonlinear identification. © 2012 John Wiley & Sons, Ltd.

Kalman and particle filtering methods for full vehicle and tyre identification

Science.gov (United States)

Bogdanski, Karol; Best, Matthew C.

2018-05-01

This paper considers identification of all significant vehicle handling dynamics of a test vehicle, including identification of a combined-slip tyre model, using only those sensors currently available on most vehicle controller area network buses. Using an appropriately simple but efficient model structure, all of the independent parameters are found from test vehicle data, with the resulting model accuracy demonstrated on independent validation data. The paper extends previous work on augmented Kalman Filter state estimators to concentrate wholly on parameter identification. It also serves as a review of three alternative filtering methods; identifying forms of the unscented Kalman filter, extended Kalman filter and particle filter are proposed and compared for effectiveness, complexity and computational efficiency. All three filters are suited to applications of system identification and the Kalman Filters can also operate in real-time in on-line model predictive controllers or estimators.

On the efficiency of high-energy particle identification statistical methods

International Nuclear Information System (INIS)

Chilingaryan, A.A.

1982-01-01

An attempt is made to analyze the statistical methods of making decisions on the high-energy particle identification. The Bayesian approach is shown to provide the most complete account of the primary discriminative information between the particles of various tupes. It does not impose rigid requirements on the density form of the probability function and ensures the account of the a priori information as compared with the Neyman-Pearson approach, the mimimax technique and the heristic rules of the decision limits construction in the variant region of the specially chosen parameter. The methods based on the concept of the nearest neighbourhood are shown to be the most effective one among the local methods of the probability function density estimation. The probability distances between the training sample classes are suggested to make a decision on selecting the high-energy particle detector optimal parameters. The method proposed and the software constructed are tested on the problem of the cosmic radiation hadron identification by means of transition radiation detectors (the ''PION'' experiment)

Comparison among four proposed direct blood culture microbial identification methods using MALDI-TOF MS.

Science.gov (United States)

Bazzi, Ali M; Rabaan, Ali A; El Edaily, Zeyad; John, Susan; Fawarah, Mahmoud M; Al-Tawfiq, Jaffar A

Matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry facilitates rapid and accurate identification of pathogens, which is critical for sepsis patients. In this study, we assessed the accuracy in identification of both Gram-negative and Gram-positive bacteria, except for Streptococcus viridans, using four rapid blood culture methods with Vitek MALDI-TOF-MS. We compared our proposed lysis centrifugation followed by washing and 30% acetic acid treatment method (method 2) with two other lysis centrifugation methods (washing and 30% formic acid treatment (method 1); 100% ethanol treatment (method 3)), and picking colonies from 90 to 180min subculture plates (method 4). Methods 1 and 2 identified all organisms down to species level with 100% accuracy, except for Streptococcus viridans, Streptococcus pyogenes, Enterobacter cloacae and Proteus vulgaris. The latter two were identified to genus level with 100% accuracy. Each method exhibited excellent accuracy and precision in terms of identification to genus level with certain limitations. Copyright © 2016 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

Comparison among four proposed direct blood culture microbial identification methods using MALDI-TOF MS

Directory of Open Access Journals (Sweden)

Ali M. Bazzi

2017-05-01

Full Text Available Summary: Matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF mass spectrometry facilitates rapid and accurate identification of pathogens, which is critical for sepsis patients.In this study, we assessed the accuracy in identification of both Gram-negative and Gram-positive bacteria, except for Streptococcus viridans, using four rapid blood culture methods with Vitek MALDI-TOF-MS. We compared our proposed lysis centrifugation followed by washing and 30% acetic acid treatment method (method 2 with two other lysis centrifugation methods (washing and 30% formic acid treatment (method 1; 100% ethanol treatment (method 3, and picking colonies from 90 to 180 min subculture plates (method 4. Methods 1 and 2 identified all organisms down to species level with 100% accuracy, except for Streptococcus viridans, Streptococcus pyogenes, Enterobacter cloacae and Proteus vulgaris. The latter two were identified to genus level with 100% accuracy. Each method exhibited excellent accuracy and precision in terms of identification to genus level with certain limitations. Keywords: MALDI-TOF, Gram-negative, Gram-positive, Sepsis, Blood culture

Stochastic output error vibration-based damage detection and assessment in structures under earthquake excitation

Science.gov (United States)

Sakellariou, J. S.; Fassois, S. D.

2006-11-01

A stochastic output error (OE) vibration-based methodology for damage detection and assessment (localization and quantification) in structures under earthquake excitation is introduced. The methodology is intended for assessing the state of a structure following potential damage occurrence by exploiting vibration signal measurements produced by low-level earthquake excitations. It is based upon (a) stochastic OE model identification, (b) statistical hypothesis testing procedures for damage detection, and (c) a geometric method (GM) for damage assessment. The methodology's advantages include the effective use of the non-stationary and limited duration earthquake excitation, the handling of stochastic uncertainties, the tackling of the damage localization and quantification subproblems, the use of "small" size, simple and partial (in both the spatial and frequency bandwidth senses) identified OE-type models, and the use of a minimal number of measured vibration signals. Its feasibility and effectiveness are assessed via Monte Carlo experiments employing a simple simulation model of a 6 storey building. It is demonstrated that damage levels of 5% and 20% reduction in a storey's stiffness characteristics may be properly detected and assessed using noise-corrupted vibration signals.

Comparison of biochemical and molecular methods for the identification of bacterial isolates associated with failed loggerhead sea turtle eggs.

Science.gov (United States)

Awong-Taylor, J; Craven, K S; Griffiths, L; Bass, C; Muscarella, M

2008-05-01

Comparison of biochemical vs molecular methods for identification of microbial populations associated with failed loggerhead turtle eggs. Two biochemical (API and Microgen) and one molecular methods (16s rRNA analysis) were compared in the areas of cost, identification, corroboration of data with other methods, ease of use, resources and software. The molecular method was costly and identified only 66% of the isolates tested compared with 74% for API. A 74% discrepancy in identifications occurred between API and 16s rRNA analysis. The two biochemical methods were comparable in cost, but Microgen was easier to use and yielded the lowest discrepancy among identifications (29%) when compared with both API 20 enteric (API 20E) and API 20 nonenteric (API 20NE) combined. A comparison of API 20E and API 20NE indicated an 83% discrepancy between the two methods. The Microgen identification system appears to be better suited than API or 16s rRNA analysis for identification of environmental isolates associated with failed loggerhead eggs. Most identification methods are not intended for use with environmental isolates. A comparison of identification systems would provide better options for identifying environmental bacteria for ecological studies.

Fast damage imaging using the time-reversal technique in the frequency–wavenumber domain

International Nuclear Information System (INIS)

Zhu, R; Huang, G L; Yuan, F G

2013-01-01

The time-reversal technique has been successfully used in structural health monitoring (SHM) for quantitative imaging of damage. However, the technique is very time-consuming when it is implemented in the time domain. In this paper, we study the technique in the frequency–wavenumber (f–k) domain for fast real-time imaging of multiple damage sites in plates using scattered flexural plate waves. Based on Mindlin plate theory, the time reversibility of dispersive flexural waves in an isotropic plate is theoretically investigated in the f–k domain. A fast damage imaging technique is developed by using the cross-correlation between the back-propagated scattered wavefield and the incident wavefield in the frequency domain. Numerical simulations demonstrate that the proposed technique cannot only localize multiple damage sites but also potentially identify their sizes. Moreover, the time-reversal technique in the f–k domain is about two orders of magnitude faster than the method in the time domain. Finally, experimental testing of an on-line SHM system with a sparse piezoelectric sensor array is conducted for fast multiple damage identification using the proposed technique. (paper)

Identification of novel human damage response proteins targeted through yeast orthology.

Directory of Open Access Journals (Sweden)

J Peter Svensson

Full Text Available Studies in Saccharomyces cerevisiae show that many proteins influence cellular survival upon exposure to DNA damaging agents. We hypothesized that human orthologs of these S. cerevisiae proteins would also be required for cellular survival after treatment with DNA damaging agents. For this purpose, human homologs of S. cerevisiae proteins were identified and mapped onto the human protein-protein interaction network. The resulting human network was highly modular and a series of selection rules were implemented to identify 45 candidates for human toxicity-modulating proteins. The corresponding transcripts were targeted by RNA interference in human cells. The cell lines with depleted target expression were challenged with three DNA damaging agents: the alkylating agents MMS and 4-NQO, and the oxidizing agent t-BuOOH. A comparison of the survival revealed that the majority (74% of proteins conferred either sensitivity or resistance. The identified human toxicity-modulating proteins represent a variety of biological functions: autophagy, chromatin modifications, RNA and protein metabolism, and telomere maintenance. Further studies revealed that MMS-induced autophagy increase the survival of cells treated with DNA damaging agents. In summary, we show that damage recovery proteins in humans can be identified through homology to S. cerevisiae and that many of the same pathways are represented among the toxicity modulators.

Identification of Dynamic Flow Stress Curves Using the Virtual Fields Methods: Theoretical Feasibility Analysis

Science.gov (United States)

Leem, Dohyun; Kim, Jin-Hwan; Barlat, Frédéric; Song, Jung Han; Lee, Myoung-Gyu

2018-03-01

An inverse approach based on the virtual fields method (VFM) is presented to identify the material hardening parameters under dynamic deformation. This dynamic-VFM (D-VFM) method does not require load information for the parameter identification. Instead, it utilizes acceleration fields in a specimen's gage region. To investigate the feasibility of the proposed inverse approach for dynamic deformation, the virtual experiments using dynamic finite element simulations were conducted. The simulation could provide all the necessary data for the identification such as displacement, strain, and acceleration fields. The accuracy of the identification results was evaluated by changing several parameters such as specimen geometry, velocity, and traction boundary conditions. The analysis clearly shows that the D-VFM which utilizes acceleration fields can be a good alternative to the conventional identification procedure that uses load information. Also, it was found that proper deformation conditions are required for generating sufficient acceleration fields during dynamic deformation to enhance the identification accuracy with the D-VFM.

The review of identification and assay methods of β-blockers

Directory of Open Access Journals (Sweden)

Ольга Олександрівна Віслоус

2015-10-01

Full Text Available Every year the number of β-blockers on the pharmaceutical market is increasing, requiring systematization of their standardization methods.Aim of research. The aim of our research is to study literature data about identification and assay methods of β-blockers with different direction of action – selective (praktolol, metoprolol, atenolol, acebutolol, betaxolol, bevantolol, bisoprolol, celiprolol, esmolol, epanolol, esatenolol, nebivolol, Talinolol, non-selective (alprenolol, Oxprenololum, pindolol, propranolol, timolol, sotalol, nadolol, mepindolol, karteol, tertatolol, bopindolol, bupranolol, penbutolol, kloranolol and combined (labetalol, carvedilol.Methods. The analytical review of literature sources about β-blockers analysis by physical, chemical, and physicochemical methods.Results. After literature sources’ analyzing it was found that physical and physicochemical constants are basically used for β-blockers pharmacopoeial analysis; both physicochemical values and chemical reactions are used in forensic analysis, resulting in the article.It was founded that titration methods, mostly acid-base titration method, are used for β-blockers assay in the analysis of substances. For β-blockers detection in biological fluids and dosage forms, active pharmaceutical ingredients and metabolites mixture separation one should prefer physicochemical methods, such as gas chromatography and liquid chromatography, absorption UV-Visible spectroscopy, fluorometry, etc.Conclusion. The results have shown can be used for the further search of the identification and assay optimal methods of β-blockers both pure and mixed with other active substances and excipients

Residual Strength Analysisof Asymmetrically Damaged Ship Hull GirderUsing Beam Finite Element Method

Directory of Open Access Journals (Sweden)

Muhammad Zubair Muis Alie

2016-04-01

Full Text Available The objective of the present study is to analyze the residual strength of asymmetrically damaged ship hull girder under longitudinal bending. Beam Finite Element Method isused for the assessment of the residual strength of two single hull bulk carriers (Ship B1 and Ship B4 and a three-cargo-hold model of a single-side Panamax Bulk Carrierin hogging and sagging conditions. The Smith’s  method  is  adopted  and  implemented  into  Beam  Finite  Element Method. An efficient solution procedure is applied; i.e. by assuming the cross section remains plane, the vertical bending moment is applied to the  cross section  and  three-cargo-hold  model. As a fundamental  case,  the  damage is simply  created  by removing the elements from the cross section, neglecting any welding residual stress and initial imperfection. Also no crack  extension  is considered.  The  result  obtained  by  Beam  Finite  Element  Method  so-called Beam-HULLST is compared to the progressive collapse analysis obtained by HULLST for the validation of the present work. Then, for the three-hold-model, the Beam-HULLST is used to investigate the effect of the rotation of the netral axisboth intact and damage condition taking the one and five frame spaces into account. 

Toxicity identification evaluation methods for identification of toxicants in refinery effluents

International Nuclear Information System (INIS)

Barten, K.A.; Mount, D.R.; Hackett, J.R.

1993-01-01

During the last five years, the authors have used Toxicity Identification Evaluation (TIE) methods to characterize and identify the source(s) of toxicity in effluents from dozens of municipal and industrial facilities. In most cases, specific chemicals responsible for toxicity have been identified. Although generally successful, the initial experience was that for several refinery effluents, they were able only to qualitatively characterize the presence of organic toxicants; standard toxicant identification procedures were not able to isolate specific organic chemicals. They believe that organic toxicity in these refinery effluents is caused by multiple organic compounds rather than by just a few; evidence for this includes an inability to isolate toxicity in a small number of fractions using liquid chromatography and the presence of very large numbers of compounds in isolated fractions. There is also evidence that the toxicant(s) may be ionic, in that the toxicity of whole effluent and isolated fractions often show increasing toxicity with decreasing pH. Finally, positive-pressure filtration has also reduced toxicity in some samples. In this presentation the authors summarize their experiences with refinery effluents, focusing on typical patterns they have observed and alternative procedures they have used to better understand the nature of these toxicants

Catalogue of methods, tools and techniques for recovery from fuel damage events

International Nuclear Information System (INIS)

1991-10-01

On the basis of the recommendations of the Advisory Group Meeting on Main Principles of Safe Management of Severely Damaged Nuclear Fuel and other Accident Generated Waste, held from 13 to 16 November 1989, the IAEA initiated a programme in 1990 to collect technical information on special tools and methods to deal with circumstances beyond the normal design basis of fuel damage. A Questionnaire was sent out to solicit information from the Member States and organizations which might have experience in this field. The responses to the Questionnaire were discussed at a Consultants Meeting and at an Advisory Group Meeting during 1990. The aim of this document is to disseminate the experience gained in Member States serving Article 5 of the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency and also filling a potential void in response to fuel damage events of less severe magnitude

Cytogenetic methods for the detection of radiation-induced chromosome damage in aquatic organisms

International Nuclear Information System (INIS)

Kligerman, A.D.

1979-01-01

One means of evaluating the genetic effects of radiation on the genomes of aquatic organisms is to screen radiation-exposed cells for chromosome aberrations. A brief literature review of studies dealing with radiation-induced chromosome damage in aquatic organisms is presented, and reasons are given detailing why most previous studies are of little quantitative value. Suggestions are made for obtaining adequate qualitative and quantitative data through the use of modern cytogenetic methods and a model systems approach to the study of cytogenetic radiation damage in aquatic organisms. Detailed procedures for both in vivo and in vitro cytogenetic methods are described, and experimental considerations are discussed. Finally, suggestions for studies that could be of value in establishing protective guidelines for aquatic ecosystems are presented. (author)

On the spot damage detection methodology for highway bridges during natural crises : tech transfer summary.

Science.gov (United States)

2010-07-01

The objective of this work was to develop a : low-cost portable damage detection tool to : assess and predict damage areas in highway : bridges. : The proposed tool was based on standard : vibration-based damage identification (VBDI) : techniques but...

UV-vis spectra as an alternative to the Lowry method for quantify hair damage induced by surfactants.

Science.gov (United States)

Pires-Oliveira, Rafael; Joekes, Inés

2014-11-01

It is well known that long term use of shampoo causes damage to human hair. Although the Lowry method has been widely used to quantify hair damage, it is unsuitable to determine this in the presence of some surfactants and there is no other method proposed in literature. In this work, a different method is used to investigate and compare the hair damage induced by four types of surfactants (including three commercial-grade surfactants) and water. Hair samples were immersed in aqueous solution of surfactants under conditions that resemble a shower (38 °C, constant shaking). These solutions become colored with time of contact with hair and its UV-vis spectra were recorded. For comparison, the amount of extracted proteins from hair by sodium dodecyl sulfate (SDS) and by water were estimated by the Lowry method. Additionally, non-pigmented vs. pigmented hair and also sepia melanin were used to understand the washing solution color and their spectra. The results presented herein show that hair degradation is mostly caused by the extraction of proteins, cuticle fragments and melanin granules from hair fiber. It was found that the intensity of solution color varies with the charge density of the surfactants. Furthermore, the intensity of solution color can be correlated to the amount of proteins quantified by the Lowry method as well as to the degree of hair damage. UV-vis spectrum of hair washing solutions is a simple and straightforward method to quantify and compare hair damages induced by different commercial surfactants. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimal Realtime Damage Identification in Composite Structures, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to develop an effective real-time, in situ damage locating and growth monitoring system of composite...

Fatigue crack detection and identification by the elastic wave propagation method

Science.gov (United States)

Stawiarski, Adam; Barski, Marek; Pająk, Piotr

2017-05-01

In this paper the elastic wave propagation phenomenon was used to detect the initiation of the fatigue damage in isotropic plate with a circular hole. The safety and reliability of structures mostly depend on the effectiveness of the monitoring methods. The Structural Health Monitoring (SHM) system based on the active pitch-catch measurement technique was proposed. The piezoelectric (PZT) elements was used as an actuators and sensors in the multipoint measuring system. The comparison of the intact and defected structures has been used by damage detection algorithm. One part of the SHM system has been responsible for detection of the fatigue crack initiation. The second part observed the evolution of the damage growth and assess the size of the defect. The numerical results of the wave propagation phenomenon has been used to present the effectiveness and accuracy of the proposed method. The preliminary experimental analysis has been carried out during the tension test of the aluminum plate with a circular hole to determine the efficiency of the measurement technique.

Inelastic damage using continuum damage mechanics in composite plate reinforced by unidirectional fibers

Directory of Open Access Journals (Sweden)

Žmindák Milan

2018-01-01

Full Text Available It is well that a finite element method is very popular simulation method to predict the physical behavior of systems and structures. In the last years an increase of interest in a new type of numerical methods known as meshless methods was observed. The paper deals with application of radial basis functions on modelling of inelastic damage using continuum damage mechanics of layered plate composite structures reinforced with long unidirectional fibers. For numerical simulations of elastic-plastic damage of layered composite plates own computational programs were implemented in MATLAB programming language. We will use the Newton-Raphson method to solve nonlinear systems of equations. Evaluation damage during plasticity has been solved using return mapping algorithm. The results of elastic-plastic damage analysis of composite plate with unsymmetrical laminate stacking sequence are presented.

Evaluation of creep damage development by the replica method; Utvaerdering av krypskadeutveckling med replikmetoden

Energy Technology Data Exchange (ETDEWEB)

Storesund, Jan [Det Norske Veritas AB, Stockholm (Sweden); Roennholm, Markku [Fortum (Sweden)

2002-04-01

Creep damage development in high temperature components can be monitored by the replica method. Damage is classified and an experience based time period for safe operation is recommended where a re-inspection should be conducted. Original recommendations are still commonly used but there are also developed ones are mostly less conservative. A data base of more than 6000 replicas, collected from welded components in Swedish and Finnish power plants, has been evaluated with respect to damage development in the present project. The results are in general in good agreement to the existing developed recommendations for re-inspections. Important factors that should be considered for use of the recommendations are highlighted: Service history, Material, welding and heat treatment, Measure of pressure and temperature, System stresses, Geometrical stress concentrations, stress distributions, Design of components and welds, Creep crack growth, Starts and stops, Extent and performance of the replica method. These factors have been analysed with respect to the evaluated data resulting in comments to the existing recommendations. In addition, recommendations and conditions for a high reliability of the replica method are described. The comments and recommendations can be read in separate sections in the end of the report.

A Rapid Identification Method for Calamine Using Near-Infrared Spectroscopy Based on Multi-Reference Correlation Coefficient Method and Back Propagation Artificial Neural Network.

Science.gov (United States)

Sun, Yangbo; Chen, Long; Huang, Bisheng; Chen, Keli

2017-07-01

As a mineral, the traditional Chinese medicine calamine has a similar shape to many other minerals. Investigations of commercially available calamine samples have shown that there are many fake and inferior calamine goods sold on the market. The conventional identification method for calamine is complicated, therefore as a result of the large scale of calamine samples, a rapid identification method is needed. To establish a qualitative model using near-infrared (NIR) spectroscopy for rapid identification of various calamine samples, large quantities of calamine samples including crude products, counterfeits and processed products were collected and correctly identified using the physicochemical and powder X-ray diffraction method. The NIR spectroscopy method was used to analyze these samples by combining the multi-reference correlation coefficient (MRCC) method and the error back propagation artificial neural network algorithm (BP-ANN), so as to realize the qualitative identification of calamine samples. The accuracy rate of the model based on NIR and MRCC methods was 85%; in addition, the model, which took comprehensive multiple factors into consideration, can be used to identify crude calamine products, its counterfeits and processed products. Furthermore, by in-putting the correlation coefficients of multiple references as the spectral feature data of samples into BP-ANN, a BP-ANN model of qualitative identification was established, of which the accuracy rate was increased to 95%. The MRCC method can be used as a NIR-based method in the process of BP-ANN modeling.

Changes of forest stands vulnerability to future wind damage resulting from different management methods

DEFF Research Database (Denmark)

Panferov, O.; Sogachev, Andrey; Ahrends, B.

2010-01-01

The structure of forests stands changes continuously as a result of forest growth and both natural and anthropogenic disturbances like windthrow or management activities – planting/cutting of trees. These structure changes can stabilize or destabilize forest stands in terms of their resistance...... to wind damage. The driving force behind the damage is the climate, but the magnitude and sign of resulting effect depend on tree species, management method and soil conditions. The projected increasing frequency of weather extremes in the whole and severe storms in particular might produce wide area...... damage in European forest ecosystems during the 21st century. To assess the possible wind damage and stabilization/destabilization effects of forest management a number of numeric experiments are carried out for the region of Solling, Germany. The coupled small-scale process-based model combining Brook90...

A feature point identification method for positron emission particle tracking with multiple tracers

Energy Technology Data Exchange (ETDEWEB)

Wiggins, Cody, E-mail: cwiggin2@vols.utk.edu [University of Tennessee-Knoxville, Department of Physics and Astronomy, 1408 Circle Drive, Knoxville, TN 37996 (United States); Santos, Roque [University of Tennessee-Knoxville, Department of Nuclear Engineering (United States); Escuela Politécnica Nacional, Departamento de Ciencias Nucleares (Ecuador); Ruggles, Arthur [University of Tennessee-Knoxville, Department of Nuclear Engineering (United States)

2017-01-21

A novel detection algorithm for Positron Emission Particle Tracking (PEPT) with multiple tracers based on optical feature point identification (FPI) methods is presented. This new method, the FPI method, is compared to a previous multiple PEPT method via analyses of experimental and simulated data. The FPI method outperforms the older method in cases of large particle numbers and fine time resolution. Simulated data show the FPI method to be capable of identifying 100 particles at 0.5 mm average spatial error. Detection error is seen to vary with the inverse square root of the number of lines of response (LORs) used for detection and increases as particle separation decreases. - Highlights: • A new approach to positron emission particle tracking is presented. • Using optical feature point identification analogs, multiple particle tracking is achieved. • Method is compared to previous multiple particle method. • Accuracy and applicability of method is explored.

Creep-fatigue life prediction for different heats of Type 304 stainless steel by linear-damage rule, strain-range partitioning method, and damage-rate approach

International Nuclear Information System (INIS)

Maiya, P.S.

1978-07-01

The creep-fatigue life results for five different heats of Type 304 stainless steel at 593 0 C (1100 0 F), generated under push-pull conditions in the axial strain-control mode, are presented. The life predictions for the various heats based on the linear-damage rule, strain-range partitioning method, and damage-rate approach are discussed. The appropriate material properties required for computation of fatigue life are also included

Vortex Tube Modeling Using the System Identification Method

Energy Technology Data Exchange (ETDEWEB)

Han, Jaeyoung; Jeong, Jiwoong; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Im, Seokyeon [Tongmyong Univ., Busan (Korea, Republic of)

2017-05-15

In this study, vortex tube system model is developed to predict the temperature of the hot and the cold sides. The vortex tube model is developed based on the system identification method, and the model utilized in this work to design the vortex tube is ARX type (Auto-Regressive with eXtra inputs). The derived polynomial model is validated against experimental data to verify the overall model accuracy. It is also shown that the derived model passes the stability test. It is confirmed that the derived model closely mimics the physical behavior of the vortex tube from both the static and dynamic numerical experiments by changing the angles of the low-temperature side throttle valve, clearly showing temperature separation. These results imply that the system identification based modeling can be a promising approach for the prediction of complex physical systems, including the vortex tube.

General Anisotropy Identification of Paperboard with Virtual Fields Method

Science.gov (United States)

J.M. Considine; F. Pierron; K.T. Turner; D.W. Vahey

2014-01-01

This work extends previous efforts in plate bending of Virtual Fields Method (VFM) parameter identification to include a general 2-D anisotropicmaterial. Such an extension was needed for instances in which material principal directions are unknown or when specimen orientation is not aligned with material principal directions. A new fixture with a multiaxial force...

A time reversal damage imaging method for structure health monitoring using Lamb waves

International Nuclear Information System (INIS)

Zhang Hai-Yan; Cao Ya-Ping; Sun Xiu-Li; Chen Xian-Hua; Yu Jian-Bo

2010-01-01

This paper investigates the Lamb wave imaging method combining time reversal for health monitoring of a metallic plate structure. The temporal focusing effect of the time reversal Lamb waves is investigated theoretically. It demonstrates that the focusing effect is related to the frequency dependency of the time reversal operation. Numerical simulations are conducted to study the time reversal behaviour of Lamb wave modes under broadband and narrowband excitations. The results show that the reconstructed time reversed wave exhibits close similarity to the reversed narrowband tone burst signal validating the theoretical model. To enhance the similarity, the cycle number of the excited signal should be increased. Experiments combining finite element model are then conducted to study the imaging method in the presence of damage like hole in the plate structure. In this work, the time reversal technique is used for the recompression of Lamb wave signals. Damage imaging results with time reversal using broadband and narrowband excitations are compared to those without time reversal. It suggests that the narrowband excitation combined time reversal can locate and determine the size of structural damage more precisely, but the cycle number of the excited signal should be chosen reasonably

A Two-Stage Method for Structural Damage Prognosis in Shear Frames Based on Story Displacement Index and Modal Residual Force

Directory of Open Access Journals (Sweden)

Asghar Rasouli

2015-01-01

Full Text Available A two-stage method is proposed to properly identify the location and the extent of damage in shear frames. In the first stage, a story displacement index (SDI is presented to precisely locate the damage in the shear frame which is calculated using the modal analysis information of the damaged structure. In the second stage, by defining a new objective function, the extent of the actual damage is determined via an imperialist competitive algorithm. The performance of the proposed method is demonstrated by implementing the technique to three examples containing five-, ten-, and twenty-five-story shear frames with noises and without them in modal data. Moreover, the performance of the proposed method has been verified through using a benchmark problem. Numerical results show the high efficiency of the proposed method for accurately identifying the location and the extent of structural damage in shear frames.

An Automatic Parameter Identification Method for a PMSM Drive with LC-Filter

DEFF Research Database (Denmark)

Bech, Michael Møller; Christensen, Jeppe Haals; Weber, Magnus L.

2016-01-01

of the PMSM fed through an LC-filter. Based on the measured current response, model parameters for both the filter (L, R, C) and the PMSM (L and R) are estimated: First, the frequency response of the system is estimated using Welch Modified Periodogram method and then an optimization algorithm is used to find...... the parameters in an analytical reference model that minimize the model error. To demonstrate the practical feasibility of the method, a fully functional drive including an embedded real-time controller has been built. In addition to modulation, data acquisition and control the whole parameter identification...... method is also implemented on the real-time controller. Based on laboratory experiments on a 22 kW drive, it is concluded that the embedded identification method can estimate the five parameters in less than ten seconds....

The identification method of the nuclear fragments in emulsions

International Nuclear Information System (INIS)

Jipa, Alexandru; Ocheseanu, Silvia; Caramarcu, Costin; Calin, Marius; Constantin, Florin; Stan, Emil

2003-01-01

The visualization detectors have been successfully used from the beginning of the study of the relativistic nuclear collisions. One of these detectors used in such experiments is the nuclear emulsion. To increase the speed of the passage from pictures to experimental data different methods and tools have been proposed during the time. For identifying the nuclear fragments obtained in the relativistic radioactive beams multiple layers of nuclear emulsions have been exposed in experiments performed at the Synchrophasotron from the JINR Dubna (BECQUEREL Collaboration). The nuclear fragments have been identified using PAVICOM scanning and measuring system. In the present work an identification method based on a real time image processing machine and a reconstruction algorithm based on special conformal transforms is proposed. The results obtained by this method are compared with those obtained using PAVICOM device. Because in this study only pictures have been used, not initial nuclear emulsions, some difficulties in the identification of the nuclear fragments with higher polar angles can appear. Generally, comparable results have been obtained. The authors thank Dr. Pavel Zarubin from JINR Dubna, Laboratory of High Energy Physics, and Dr. Maria Haiduc, Institute of Space Sciences Bucharest-Magurele, for the pictures of the nuclear emulsions exposed in these experiments. (authors)

A comparison of Heuristic method and Llewellyn’s rules for identification of redundant constraints

Science.gov (United States)

Estiningsih, Y.; Farikhin; Tjahjana, R. H.

2018-03-01

Important techniques in linear programming is modelling and solving practical optimization. Redundant constraints are consider for their effects on general linear programming problems. Identification and reduce redundant constraints are for avoidance of all the calculations associated when solving an associated linear programming problems. Many researchers have been proposed for identification redundant constraints. This paper a compararison of Heuristic method and Llewellyn’s rules for identification of redundant constraints.

System identification by methods from the statistical signal theory, history and state of the art

International Nuclear Information System (INIS)

Christensen, Palle; Gundersen, Vidar B.

1999-01-01

Condition monitoring is an important area in which the OECD Halden Reactor Project has developed several tools. This paper presents a general overview of methods utilised in diagnosis systems, signal validation systems and process optimisation systems such as EFD, Mocom, Aladdin and PEANO. An overview of lessons learned on diagnosis of technical systems with special reference to system identification is reported. The analysis of input-output behaviour by special, suitable methods may be used as a tool for diagnosis. An overview of methods for empirical modelling and data analysis and their major differences is presented. It is explained how system identification methods and transforms may be used to build models based on observed data from a system. According to the Webster dictionary diagnosis is 'Investigation or analysis of the cause or nature of a condition, situation or a problem.' By examining data collected from a process the aim is to detect abnormal conditions and if possible understand what has been the cause of the observed problem. Section 1 gives a retrospective view at the development in the field of system identification. Section 2 presents a classification of the methods, while section 3 provides some practical advice on how diagnosis can be carried out by means of system identification methods (author) (ml)

Dynamic Friction Parameter Identification Method with LuGre Model for Direct-Drive Rotary Torque Motor

Directory of Open Access Journals (Sweden)

Xingjian Wang

2016-01-01

Full Text Available Attainment of high-performance motion/velocity control objectives for the Direct-Drive Rotary (DDR torque motor should fully consider practical nonlinearities in controller design, such as dynamic friction. The LuGre model has been widely utilized to describe nonlinear friction behavior; however, parameter identification for the LuGre model remains a challenge. A new dynamic friction parameter identification method for LuGre model is proposed in this study. Static parameters are identified through a series of constant velocity experiments, while dynamic parameters are obtained through a presliding process. Novel evolutionary algorithm (NEA is utilized to increase identification accuracy. Experimental results gathered from the identification experiments conducted in the study for a practical DDR torque motor control system validate the effectiveness of the proposed method.

Systems and methods for remote long standoff biometric identification using microwave cardiac signals

Science.gov (United States)

McGrath, William R. (Inventor); Talukder, Ashit (Inventor)

2012-01-01

Systems and methods for remote, long standoff biometric identification using microwave cardiac signals are provided. In one embodiment, the invention relates to a method for remote biometric identification using microwave cardiac signals, the method including generating and directing first microwave energy in a direction of a person, receiving microwave energy reflected from the person, the reflected microwave energy indicative of cardiac characteristics of the person, segmenting a signal indicative of the reflected microwave energy into a waveform including a plurality of heart beats, identifying patterns in the microwave heart beats waveform, and identifying the person based on the identified patterns and a stored microwave heart beats waveform.

Concealed identification symbols and nondestructive determination of the identification symbols

Science.gov (United States)

Nance, Thomas A.; Gibbs, Kenneth M.

2014-09-16

The concealing of one or more identification symbols into a target object and the subsequent determination or reading of such symbols through non-destructive testing is described. The symbols can be concealed in a manner so that they are not visible to the human eye and/or cannot be readily revealed to the human eye without damage or destruction of the target object. The identification symbols can be determined after concealment by e.g., the compilation of multiple X-ray images. As such, the present invention can also provide e.g., a deterrent to theft and the recovery of lost or stolen objects.

Direct Linear System Identification Method for Multistory Three-dimensional Building Structure with General Eccentricity

OpenAIRE

Shintani, Kenichirou; Yoshitomi, Shinta; Takewaki, Izuru

2017-01-01

A method of physical parameter system identification (SI) is proposed here for three-dimensional (3D) building structures with in-plane rigid floors in which the stiffness and damping coefficients of each structural frame in the 3D building structure are identified from the measured floor horizontal accelerations. A batch processing least-squares estimation method for many discrete time domain measured data is proposed for the direct identification of the stiffness and damping coefficients of...

[Bacterial identification methods in the microbiology laboratory].

Science.gov (United States)

Bou, Germán; Fernández-Olmos, Ana; García, Celia; Sáez-Nieto, Juan Antonio; Valdezate, Sylvia

2011-10-01

In order to identify the agent responsible of the infectious process and understanding the pathogenic/pathological implications, clinical course, and to implement an effective antimicrobial therapy, a mainstay in the practice of clinical microbiology is the allocation of species to a microbial isolation. In daily routine practice microbiology laboratory phenotypic techniques are applied to achieve this goal. However, they have some limitations that are seen more clearly for some kinds of microorganism. Molecular methods can circumvent some of these limitations, although its implementation is not universal. This is due to higher costs and the level of expertise required for thei implementation, so molecular methods are often centralized in reference laboratories and centers. Recently, proteomics-based methods made an important breakthrough in the field of diagnostic microbiology and will undoubtedly have a major impact on the future organization of the microbiology services. This paper is a short review of the most noteworthy aspects of the three bacterial identification methods described above used in microbiology laboratories. Copyright © 2011 Elsevier España, S.L. All rights reserved.

Experimental system identification of the dynamics of a vibro-impact beam with a view towards structural health monitoring and damage detection

Science.gov (United States)

Chen, Heng; Kurt, Mehmet; Lee, Young S.; McFarland, D. Michael; Bergman, Lawrence A.; Vakakis, Alexander F.

2014-05-01

We perform nonlinear system identification (NSI) on the acceleration signals that were experimentally measured at ten, almost evenly spaced positions along a cantilever beam undergoing vibro-impacts between two rigid stops with clearances. Our goal is to characterize the nonlinear dynamics due to vibro-impacts with a view toward structural health monitoring (SHM) and damage detection (DD). The NSI methodology is based on the correspondence between analytical and empirical slow-flow dynamics, with the first step requiring empirical mode decomposition (EMD) analysis of the measured time series leading to sets of intrinsic modal oscillators (IMOs) governing the vibro-impact dynamics at different time scales. By comparing the spatiotemporal variations of the nonlinear modal interactions (and hence the IMOs), we examine how vibro-impacts influence the low- and high-frequency modes in global and local senses. In applications of the NSI results to SHM/DD, we calculate typical measures such as the modal assurance criterion (MAC) and the coordinate modal assurance criterion (COMAC) by extracting information about the mode shape functions from the spatiotemporal IMO solutions. Whereas the MAC provides a global aspect of damage occurrence (i.e., which modes are more affected by induced defects), the COMAC can narrow down the damage locations (i.e., where in the structure defects exist that yield low correlation values in specific modes).

Damage assessment using flexibility and flexibility-based curvature for structural health monitoring

International Nuclear Information System (INIS)

Catbas, F N; Gul, M; Burkett, J L

2008-01-01

As a result of the recent advances in sensors, information technologies and material science, a considerable amount of research has been conducted in the area of smart infrastructures. While there are many important components of a smart infrastructure, an automated and continuous structural health monitoring (SHM) system is a critical one. SHM is typically used to track and evaluate the performance of a structure, symptoms of operational incidents, anomalies due to deterioration and damage during regular operation as well as after an extreme event. Successful health monitoring applications can be achieved by integrating experimental, analytical and information technologies on real-life operating structures. However, real-life investigations must be backed up by laboratory benchmark studies for validating theory, concepts, and new technologies. For this reason, a physical bridge model is developed to implement SHM methods and technologies. In this study, different aspects of model development are outlined in terms of design considerations, instrumentation, finite element modeling, and simulating damage scenarios. Different damage detection methods are evaluated using the numerical and the physical models. Modal parameter estimation studies are carried out to reliably identify the eigenvalues, eigenvectors and modal scaling from the measurement data. To assess the simulated damage, modal flexibility-based displacements and curvatures are employed. Structural behavior after damage is evaluated by inspecting the deflected shapes obtained using modal flexibility. More localized damage simulations such as stiffness reduction at a joint yield a very subtle stiffness decrease. In this case, the writers use a baseline to identify damage and also investigate the use of curvature as a complementary index. Curvature is advantageous for certain cases where the displacement results do not provide substantial changes. Issues related to using curvature as a damage identification

Identification of the corporate values of an enterprise: theory, approaches, methodic

Directory of Open Access Journals (Sweden)

Kozlov Vladimir Aleksandrovich

2015-07-01

Full Text Available This article focuses on research and composition of the instrument to identify the corporate values of the enterprise and practical activities to support them. The first part based on theoretical evidence of essence and correlation between notions of ‘Corporate culture’ and ‘Corporate values’. The method of corporate values identification, based on indirect approach, is proposed and the examples are provided. The results of implemented project for corporate values identification at industrial enterprise are presented. For further support the tasks and activities for corporate values management are proposed.

The engine maintenance scheduling by using reliability centered maintenance method and the identification of 5S application in PT. XYZ

Science.gov (United States)

Sembiring, N.; Panjaitan, N.; Saragih, A. F.

2018-02-01

PT. XYZ is a manufacturing company that produces fresh fruit bunches (FFB) to Crude Palm Oil (CPO) and Palm Kernel Oil (PKO). PT. XYZ consists of six work stations: receipt station, sterilizing station, thressing station, pressing station, clarification station, and kernelery station. So far, the company is still implementing corrective maintenance maintenance system for production machines where the machine repair is done after damage occurs. Problems at PT. XYZ is the absence of scheduling engine maintenance in a planned manner resulting in the engine often damaged which can disrupt the smooth production. Another factor that is the problem in this research is the kernel station environment that becomes less convenient for operators such as there are machines and equipment not used in the production area, slippery, muddy, scattered fibers, incomplete use of PPE, and lack of employee discipline. The most commonly damaged machine is in the seed processing station (kernel station) which is cake breaker conveyor machine. The solution of this problem is to propose a schedule plan for maintenance of the machine by using the method of reliability centered maintenance and also the application of 5S. The result of the application of Reliability Centered maintenance method is obtained four components that must be treated scheduled (time directed), namely: for bearing component is 37 days, gearbox component is 97 days, CBC pen component is 35 days and conveyor pedal component is 32 days While after identification the application of 5S obtained the proposed corporate environmental improvement measures in accordance with the principles of 5S where unused goods will be moved from the production area, grouping goods based on their use, determining the procedure of cleaning the production area, conducting inspection in the use of PPE, and making 5S slogans.

Noncontact blood species identification method based on spatially resolved near-infrared transmission spectroscopy

Science.gov (United States)

Zhang, Linna; Sun, Meixiu; Wang, Zhennan; Li, Hongxiao; Li, Yingxin; Li, Gang; Lin, Ling

2017-09-01

The inspection and identification of whole blood are crucially significant for import-export ports and inspection and quarantine departments. In our previous research, we proved Near-Infrared diffuse transmitted spectroscopy method was potential for noninvasively identifying three blood species, including macaque, human and mouse, with samples measured in the cuvettes. However, in open sampling cases, inspectors may be endangered by virulence factors in blood samples. In this paper, we explored the noncontact measurement for classification, with blood samples measured in the vacuum blood vessels. Spatially resolved near-infrared spectroscopy was used to improve the prediction accuracy. Results showed that the prediction accuracy of the model built with nine detection points was more than 90% in identification between all five species, including chicken, goat, macaque, pig and rat, far better than the performance of the model built with single-point spectra. The results fully supported the idea that spatially resolved near-infrared spectroscopy method can improve the prediction ability, and demonstrated the feasibility of this method for noncontact blood species identification in practical applications.

Detecting Structural Damage of Nuclear Power Plant by Interactive Data Mining Approach

International Nuclear Information System (INIS)

Yufei Shu

2006-01-01

This paper presents a nonlinear structural damage identification technique, based on an interactive data mining approach, which integrates a human cognitive model in a data mining loop. A mining control agent emulating human analysts is developed, which directly interacts with the data miner, analyzing and verifying the output of the data miner and controlling the data mining process. Additionally, an artificial neural network method, which is adopted as a core component of the proposed interactive data mining method, is evolved by adding a novelty detecting and retraining function for handling complicated nuclear power plant quake-proof data. Plant quake-proof testing data has been applied to the system to show the validation of the proposed method. (author)

Analysis and research status of severe core damage accidents

International Nuclear Information System (INIS)

1984-03-01

The Severe Core Damage Research and Analysis Task Force was established in Nuclear Safety Research Center, Tokai Research Establishment, JAERI, in May, 1982 to make a quantitative analysis on the issues related with the severe core damage accident and also to survey the present status of the research and provide the required research subjects on the severe core damage accident. This report summarizes the results of the works performed by the Task Force during last one and half years. The main subjects investigated are as follows; (1) Discussion on the purposes and necessities of severe core damage accident research, (2) proposal of phenomenological research subjects required in Japan, (3) analysis of severe core damage accidents and identification of risk dominant accident sequences, (4) investigation of significant physical phenomena in severe core damage accidents, and (5) survey of the research status. (author)

A gradient enhanced plasticity-damage microplane model for concrete

Science.gov (United States)

Zreid, Imadeddin; Kaliske, Michael

2018-03-01

Computational modeling of concrete poses two main types of challenges. The first is the mathematical description of local response for such a heterogeneous material under all stress states, and the second is the stability and efficiency of the numerical implementation in finite element codes. The paper at hand presents a comprehensive approach addressing both issues. Adopting the microplane theory, a combined plasticity-damage model is formulated and regularized by an implicit gradient enhancement. The plasticity part introduces a new microplane smooth 3-surface cap yield function, which provides a stable numerical solution within an implicit finite element algorithm. The damage part utilizes a split, which can describe the transition of loading between tension and compression. Regularization of the model by the implicit gradient approach eliminates the mesh sensitivity and numerical instabilities. Identification methods for model parameters are proposed and several numerical examples of plain and reinforced concrete are carried out for illustration.

Damage Localization of Cable-Supported Bridges Using Modal Frequency Data and Probabilistic Neural Network

Directory of Open Access Journals (Sweden)

X. T. Zhou

2014-01-01

Full Text Available This paper presents an investigation on using the probabilistic neural network (PNN for damage localization in the suspension Tsing Ma Bridge (TMB and the cable-stayed Ting Kau Bridge (TKB from simulated noisy modal data. Because the PNN approach describes measurement data in a Bayesian probabilistic framework, it is promising for structural damage detection in noisy conditions. For locating damage on the TMB deck, the main span of the TMB is divided into a number of segments, and damage to the deck members in a segment is classified as one pattern class. The characteristic ensembles (training samples for each pattern class are obtained by computing the modal frequency change ratios from a 3D finite element model (FEM when incurring damage at different members of the same segment and then corrupting the analytical results with random noise. The testing samples for damage localization are obtained in a similar way except that damage is generated at locations different from the training samples. For damage region/type identification of the TKB, a series of pattern classes are defined to depict different scenarios with damage occurring at different portions/components. Research efforts have been focused on evaluating the influence of measurement noise level on the identification accuracy.

Simple Sample Preparation Method for Direct Microbial Identification and Susceptibility Testing From Positive Blood Cultures.

Science.gov (United States)

Pan, Hong-Wei; Li, Wei; Li, Rong-Guo; Li, Yong; Zhang, Yi; Sun, En-Hua

2018-01-01

Rapid identification and determination of the antibiotic susceptibility profiles of the infectious agents in patients with bloodstream infections are critical steps in choosing an effective targeted antibiotic for treatment. However, there has been minimal effort focused on developing combined methods for the simultaneous direct identification and antibiotic susceptibility determination of bacteria in positive blood cultures. In this study, we constructed a lysis-centrifugation-wash procedure to prepare a bacterial pellet from positive blood cultures, which can be used directly for identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and antibiotic susceptibility testing by the Vitek 2 system. The method was evaluated using a total of 129 clinical bacteria-positive blood cultures. The whole sample preparation process could be completed in identification was 96.49% for gram-negative bacteria and 97.22% for gram-positive bacteria. Vitek 2 antimicrobial susceptibility testing of gram-negative bacteria showed an agreement rate of antimicrobial categories of 96.89% with a minor error, major error, and very major error rate of 2.63, 0.24, and 0.24%, respectively. Category agreement of antimicrobials against gram-positive bacteria was 92.81%, with a minor error, major error, and very major error rate of 4.51, 1.22, and 1.46%, respectively. These results indicated that our direct antibiotic susceptibility analysis method worked well compared to the conventional culture-dependent laboratory method. Overall, this fast, easy, and accurate method can facilitate the direct identification and antibiotic susceptibility testing of bacteria in positive blood cultures.

Damage detection of rotating wind turbine blades using local flexibility method and long-gauge fiber Bragg grating sensors

Science.gov (United States)

Hsu, Ting-Yu; Shiao, Shen-Yuan; Liao, Wen-I.

2018-01-01

Wind turbines are a cost-effective alternative energy source; however, their blades are susceptible to damage. Therefore, damage detection of wind turbine blades is of great importance for condition monitoring of wind turbines. Many vibration-based structural damage detection techniques have been proposed in the last two decades. The local flexibility method, which can determine local stiffness variations of beam-like structures by using measured modal parameters, is one of the most promising vibration-based approaches. The local flexibility method does not require a finite element model of the structure. A few structural modal parameters identified from the ambient vibration signals both before and after damage are required for this method. In this study, we propose a damage detection approach for rotating wind turbine blades using the local flexibility method based on the dynamic macro-strain signals measured by long-gauge fiber Bragg grating (FBG)-based sensors. A small wind turbine structure was constructed and excited using a shaking table to generate vibration signals. The structure was designed to have natural frequencies as close as possible to those of a typical 1.5 MW wind turbine in real scale. The optical fiber signal of the rotating blades was transmitted to the data acquisition system through a rotary joint fixed inside the hollow shaft of the wind turbine. Reversible damage was simulated by aluminum plates attached to some sections of the wind turbine blades. The damaged locations of the rotating blades were successfully detected using the proposed approach, with the extent of damage somewhat over-estimated. Nevertheless, although the specimen of wind turbine blades cannot represent a real one, the results still manifest that FBG-based macro-strain measurement has potential to be employed to obtain the modal parameters of the rotating wind turbines and then locations of wind turbine segments with a change of rigidity can be estimated effectively by

A method for estimating the local area economic damages of Superfund waste sites

International Nuclear Information System (INIS)

Walker, D.R.

1992-01-01

National Priority List (NPL) sites, or more commonly called Superfund sites, are hazardous waste sites (HWS) deemed by the Environmental Protection Agency (EPA) to impose the greatest risks to human health or welfare or to the environment. HWS are placed and ranked for cleanup on the NPL based on a score derived from the Hazard Ranking System (HRS), which is a scientific assessment of the health and environmental risks posed by HWS. A concern of the HRS is that the rank of sites is not based on benefit-cost analysis. The main objective of this dissertation is to develop a method for estimating the local area economic damages associated with Superfund waste sites. Secondarily, the model is used to derive county-level damage estimates for use in ranking the county level damages from Superfund sites. The conceptual model used to describe the damages associated with Superfund sites is a household-firm location decision model. In this model assumes that households and firms make their location choice based on the local level of wages, rents and amenities. The model was empirically implemented using 1980 census microdata on households and workers in 253 counties across the US. The household sample includes data on the value and structural characteristics of homes. The worker sample includes the annual earnings of workers and a vector worker attributes. The microdata was combined with county level amenity data, including the number of Superfund sites. The hedonic pricing technique was used to estimate the effect of Superfund sites on average annual wages per household and on monthly expenditures on housing. The results show that Superfund sites impose statistically significant damages on households. The annual county damages from Superfund sites for a sample of 151 counties was over 14 billion dollars. The ranking of counties using the damage estimates is correlated with the rank of counties using the HRS

Finite element method for viscoelastic medium with damage and the application to structural analysis of solid rocket motor grain

Science.gov (United States)

Deng, Bin; Shen, ZhiBin; Duan, JingBo; Tang, GuoJin

2014-05-01

This paper studies the damage-viscoelastic behavior of composite solid propellants of solid rocket motors (SRM). Based on viscoelastic theories and strain equivalent hypothesis in damage mechanics, a three-dimensional (3-D) nonlinear viscoelastic constitutive model incorporating with damage is developed. The resulting viscoelastic constitutive equations are numerically discretized by integration algorithm, and a stress-updating method is presented by solving nonlinear equations according to the Newton-Raphson method. A material subroutine of stress-updating is made up and embedded into commercial code of Abaqus. The material subroutine is validated through typical examples. Our results indicate that the finite element results are in good agreement with the analytical ones and have high accuracy, and the suggested method and designed subroutine are efficient and can be further applied to damage-coupling structural analysis of practical SRM grain.

Rapid identification of ascomycetous yeasts from clinical specimens by a molecular method based on flow cytometry and comparison with identifications from phenotypic assays.

Science.gov (United States)

Page, Brent T; Shields, Christine E; Merz, William G; Kurtzman, Cletus P

2006-09-01

This study was designed to compare the identification of ascomycetous yeasts recovered from clinical specimens by using phenotypic assays (PA) and a molecular flow cytometric (FC) method. Large-subunit rRNA domains 1 and 2 (D1/D2) gene sequence analysis was also performed and served as the reference for correct strain identification. A panel of 88 clinical isolates was tested that included representatives of nine commonly encountered species and six infrequently encountered species. The PA included germ tube production, fermentation of seven carbohydrates, morphology on corn meal agar, urease and phenoloxidase activities, and carbohydrate assimilation tests when needed. The FC method (Luminex) employed species-specific oligonucleotides attached to polystyrene beads, which were hybridized with D1/D2 amplicons from the unidentified isolates. The PA identified 81 of 88 strains correctly but misidentified 4 of Candida dubliniensis, 1 of C. bovina, 1 of C. palmioleophila, and 1 of C. bracarensis. The FC method correctly identified 79 of 88 strains and did not misidentify any isolate but did not identify nine isolates because oligonucleotide probes were not available in the current library. The FC assay takes approximately 5 h, whereas the PA takes from 2 h to 5 days for identification. In conclusion, PA did well with the commonly encountered species, was not accurate for uncommon species, and takes significantly longer than the FC method. These data strongly support the potential of FC technology for rapid and accurate identification of medically important yeasts. With the introduction of new antifungals, rapid, accurate identification of pathogenic yeasts is more important than ever for guiding antifungal chemotherapy.

Seismic damage assessment for high-rise buildings

Science.gov (United States)

Scholl, Roger E.

1980-01-01

The problem considered in this project, conducted by URS/John A. Blume & Associates, Engineers (URS/Blume), for the U.S. Geological Survey, is the identification, evaluation, and correlation of ground-motion and structural parameters in order to improve procedures for predicting dollar losses for high-rise structures damaged by earthquakes. Ground-motion data bases, analytical techniques, and known motion-damage relationships already developed for high-rise buildings and for other classes of structures will be refined and extended so that reliable quantitative seismic risk evaluations can be made.

A Novel Coupled State/Input/Parameter Identification Method for Linear Structural Systems

Directory of Open Access Journals (Sweden)

Zhimin Wan

2018-01-01

Full Text Available In many engineering applications, unknown states, inputs, and parameters exist in the structures. However, most methods require one or two of these variables to be known in order to identify the other(s. Recently, the authors have proposed a method called EGDF for coupled state/input/parameter identification for nonlinear system in state space. However, the EGDF method based solely on acceleration measurements is found to be unstable, which can cause the drift of the identified inputs and displacements. Although some regularization methods can be adopted for solving the problem, they are not suitable for joint input-state identification in real time. In this paper, a strategy of data fusion of displacement and acceleration measurements is used to avoid the low-frequency drift in the identified inputs and structural displacements for linear structural systems. Two numerical examples about a plane truss and a single-stage isolation system are conducted to verify the effectiveness of the proposed modified EGDF algorithm.

An improved wavelet-Galerkin method for dynamic response reconstruction and parameter identification of shear-type frames

Science.gov (United States)

Bu, Haifeng; Wang, Dansheng; Zhou, Pin; Zhu, Hongping

2018-04-01

An improved wavelet-Galerkin (IWG) method based on the Daubechies wavelet is proposed for reconstructing the dynamic responses of shear structures. The proposed method flexibly manages wavelet resolution level according to excitation, thereby avoiding the weakness of the wavelet-Galerkin multiresolution analysis (WGMA) method in terms of resolution and the requirement of external excitation. IWG is implemented by this work in certain case studies, involving single- and n-degree-of-freedom frame structures subjected to a determined discrete excitation. Results demonstrate that IWG performs better than WGMA in terms of accuracy and computation efficiency. Furthermore, a new method for parameter identification based on IWG and an optimization algorithm are also developed for shear frame structures, and a simultaneous identification of structural parameters and excitation is implemented. Numerical results demonstrate that the proposed identification method is effective for shear frame structures.

Characterization and calibration of radiation-damaged double-sided silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Kaya, L. [Institut für Kernphysik, Universität zu Köln, D-50937 Köln (Germany); Vogt, A., E-mail: andreas.vogt@ikp.uni-koeln.de [Institut für Kernphysik, Universität zu Köln, D-50937 Köln (Germany); Reiter, P.; Birkenbach, B.; Hirsch, R.; Arnswald, K.; Hess, H.; Seidlitz, M.; Steinbach, T.; Warr, N.; Wolf, K. [Institut für Kernphysik, Universität zu Köln, D-50937 Köln (Germany); Stahl, C.; Pietralla, N. [Institut für Kernphysik, Technische Universität Darmstadt, D-64291 Darmstadt (Germany); Limböck, T.; Meerholz, K. [Physikalische Chemie, Universität zu Köln, D-50939 Köln (Germany); Lutter, R. [Maier-Leibnitz-Laboratorium, Ludwig-Maximilians-Universität München, D-85748 Garching (Germany)

2017-05-21

Double-sided silicon strip detectors (DSSSD) are commonly used for event-by-event identification of charged particles as well as the reconstruction of particle trajectories in nuclear physics experiments with stable and radioactive beams. Intersecting areas of both p- and n-doped front- and back-side segments form individual virtual pixel segments allowing for a high detector granularity. DSSSDs are employed in demanding experimental environments and have to withstand high count rates of impinging nuclei. The illumination of the detector is often not homogeneous. Consequently, radiation damage of the detector is distributed non-uniformly. Position-dependent incomplete charge collection due to radiation damage limits the performance and lifetime of the detectors, the response of different channels may vary drastically. Position-resolved charge-collection losses between front- and back-side segments are investigated in an in-beam experiment and by performing radioactive source measurements. A novel position-resolved calibration method based on mutual consistency of p-side and n-side charges yields a significant enhancement of the energy resolution and the performance of radiation-damaged parts of the detector.

In-core sipping method for the identification of failed fuel assemblies

International Nuclear Information System (INIS)

Wu Zhongwang; Zhang Yajun

2000-01-01

The failed fuel assembly identification system is an important safety system which ensures safe operations of reactor and immediate treatment of failed fuel rod cladding. The system uses an internationally recognized method to identify failed fuel assemblies in a reactor with fuel element cases. The in-core sipping method is customary used to identify failed fuel assemblies during refueling or after fuel rod cladding failure accidents. The test is usually performed after reactor shutdown by taking samples from each fuel element case while the cases are still in their original core positions. The sample activity is then measured to identify failed fuel assemblies. A failed fuel assembly identification system was designed for the NHR-200 based on the properties of the NHR-200 and national requirements. the design provides an internationally recognized level of safety to ensure the safety of NHR-200

Fixture and method for rectifying damaged guide thimble insert sleeves in a reconstitutable fuel assembly

International Nuclear Information System (INIS)

Shallenberger, J.M.; Ferlan, S.J.

1987-01-01

A guide thimble damage-rectifying method is described for use on a reconstitutable fuel assembly being held in a work station with its top nozzle removed to expose a plurality of guide thimbles having one of several different types of damage. The method consists of: (a) providing a base having a plurality of tool positioning openings defined therein in a pattern matched with that of the guide thimbles of the fuel assembly; (b) mounting the base on the work station with its tool positioning openings in alignment with the guide thimbles of the fuel assembly and such that the base is movable toward the guide thimbles; (c) providing a plurality of different tools each operable to rectify one of the different types of guide thimble damage; (d) mounting selected ones of the different tools in respective ones of the openings of the base in alignment with ones of the thimbles having the respective types of guide thimble damage capable of being rectified by the selected tools such that upon movement of the base toward the guide thimbles the respective types of guide thimble damage will be rectified by the selected tools; (e) providing a group of positioning elements; (f) mounting the positioning elements in selected ones of the base openings corresponding to undamaged ones of the guide thimbles such that upon movement of the base toward the guide thimbles the positioning elements become mounted on upper end portions of the corresponding undamaged ones of the guide thimbles for precisely locating the fixture relative to the guide thimble upper end portions for accurate performance of the repairable damage rectifying operation by the tools as the base is moved toward the guide thimbles; and (g) moving the base toward the guide thimbles so as to mount the positioning elements on the corresponding ones of the undamaged guide thimbles and effect rectification of the damaged guide thimbles by the selected tools

A New Method of Gold Foil Damage Detection in Stone Carving Relics Based on Multi-Temporal 3D LiDAR Point Clouds

Directory of Open Access Journals (Sweden)

Miaole Hou

2016-05-01

Full Text Available The timely detection of gold foil damage in gold-overlaid stone carvings and the associated maintenance of these relics pose several challenges to both the research and heritage protection communities internationally. This paper presents a new method for detecting gold foil damage by making use of multi-temporal 3D LiDAR point clouds. By analyzing the errors involved in the detection process, a formula is developed for calculation of the damage detection threshold. An improved division method for the linear octree that only allocates memory to the non-blank nodes, is proposed, which improves storage and retrieval efficiency for the point clouds. Meanwhile, the damage-occurrence regions are determined according to Hausdorff distances. Using a triangular mesh, damaged regions can be identified and measured in order to determine the relic’s total damaged area. Results demonstrate that this method can effectively detect gold foil damage in stone carvings. The identified surface area of damaged regions can provide the information needed for subsequent restoration and protection of relics of this type.

Particle identification method in the CsI(Tl) scintillator used for the CHIMERA 4 pi detector

CERN Document Server

Alderighi, M; Basssini, R; Berceanu, I; Blicharska, J; Boiano, C; Borderie, B; Bougault, R; Bruno, M; Cali, C; Cardella, G; Cavallaro, S; D'Agostino, M; D'andrea, M; Dayras, R; De Filippo, E; Fichera, F; Geraci, E; Giustolisi, F; Grzeszczuk, A; Guardone, N; Guazzoni, P; Guinet, D; Iacono-Manno, M; Kowalski, S; La Guidara, E; Lanchais, A L; Lanzalone, G; Lanzanò, G; Le Neindre, N; Li, S; Maiolino, C; Majka, Z; Manfredi, G; Nicotra, D; Paduszynski, T; Pagano, A; Papa, M; Petrovici, C M; Piasecki, E; Pirrone, S; Politi, G; Pop, A; Porto, F; Rivet, M F; Rosato, E; Sacca, G; Sechi, G; Simion, V; Sperduto, M L; Steckmeyer, J C; Trifiró, A; Trimarchi, M; Urso, S; Vannini, G; Vigilante, M; Wilczynski, J; Wu, H; Xiao, Z; Zetta, L; Zipper, W

2002-01-01

The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4 pi heavy-ion detector is presented. A simple double-gate integration method, with the use of the cyclotron radiofrequency as reference time, results in low thresholds for isotopic particle identification. The dependence of the identification quality on the gate generation timing is discussed. Isotopic identification of light ions up to Beryllium is clearly seen. For the first time also the identification of Z=5 particles is observed. The identification of neutrons interacting with CsI(Tl) by (n,alpha) and (n,gamma) reactions is also discussed.

Comparison of various structural damage tracking techniques with unknown excitations based on experimental data

Science.gov (United States)

Huang, Hongwei; Yang, Jann N.; Zhou, Li

2009-03-01

An early detection of structural damages is critical for the decision making of repair and replacement maintenance in order to guarantee a specified structural reliability. Consequently, the structural damage detection, based on vibration data measured from the structural health monitoring (SHM) system, has received considerable attention recently. The traditional time-domain analysis techniques, such as the least square estimation (LSE) method and the extended Kalman filter (EKF) approach, require that all the external excitations (inputs) be available, which may not be the case for some SHM systems. Recently, these two approaches have been extended to cover the general case where some of the external excitations (inputs) are not measured, referred to as the LSE with unknown inputs (LSE-UI) and the EKF with unknown inputs (EKF-UI). Also, new analysis methods, referred to as the sequential non-linear least-square estimation with unknown inputs and unknown outputs (SNLSE-UI-UO) and the quadratic sum-square error with unknown inputs (QSSE-UI), have been proposed for the damage tracking of structures when some of the acceleration responses are not measured and the external excitations are not available. In this paper, these newly proposed analysis methods will be compared in terms of accuracy, convergence and efficiency, for damage identification of structures based on experimental data obtained through a series of experimental tests using a small-scale 3-story building model with white noise excitation. The capability of the LSE-UI, EKF-UI, SNLSE-UI-UO and QSSE-UI approaches in tracking the structural damages will be demonstrated.

Simple Sample Preparation Method for Direct Microbial Identification and Susceptibility Testing From Positive Blood Cultures

Directory of Open Access Journals (Sweden)

Hong-wei Pan

2018-03-01

Full Text Available Rapid identification and determination of the antibiotic susceptibility profiles of the infectious agents in patients with bloodstream infections are critical steps in choosing an effective targeted antibiotic for treatment. However, there has been minimal effort focused on developing combined methods for the simultaneous direct identification and antibiotic susceptibility determination of bacteria in positive blood cultures. In this study, we constructed a lysis-centrifugation-wash procedure to prepare a bacterial pellet from positive blood cultures, which can be used directly for identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS and antibiotic susceptibility testing by the Vitek 2 system. The method was evaluated using a total of 129 clinical bacteria-positive blood cultures. The whole sample preparation process could be completed in <15 min. The correct rate of direct MALDI-TOF MS identification was 96.49% for gram-negative bacteria and 97.22% for gram-positive bacteria. Vitek 2 antimicrobial susceptibility testing of gram-negative bacteria showed an agreement rate of antimicrobial categories of 96.89% with a minor error, major error, and very major error rate of 2.63, 0.24, and 0.24%, respectively. Category agreement of antimicrobials against gram-positive bacteria was 92.81%, with a minor error, major error, and very major error rate of 4.51, 1.22, and 1.46%, respectively. These results indicated that our direct antibiotic susceptibility analysis method worked well compared to the conventional culture-dependent laboratory method. Overall, this fast, easy, and accurate method can facilitate the direct identification and antibiotic susceptibility testing of bacteria in positive blood cultures.

Identification of the parameters of an elastic material model using the constitutive equation gap method

KAUST Repository

Florentin, Éric

2010-04-23

Today, the identification ofmaterialmodel parameters is based more and more on full-field measurements. This article explains how an appropriate use of the constitutive equation gap method (CEGM) can help in this context. The CEGM is a well-known concept which, until now, has been used mainly for the verification of finite element simulations. This has led to many developments, especially concerning the techniques for constructing statically admissible stress fields. The originality of the present study resides in the application of these recent developments to the identification problem. The proposed CEGM is described in detail, then evaluated through the identification of heterogeneous isotropic elastic properties. The results obtained are systematically compared with those of the equilibrium gap method, which is a well-known technique for the resolution of such identification problems. We prove that the use of the enhanced CEGM significantly improves the quality of the results. © Springer-Verlag 2010.

The use of the DInSAR method in the monitoring of road damage caused by mining activities

Science.gov (United States)

Murdzek, Radosław; Malik, Hubert; Leśniak, Andrzej

2018-04-01

This paper reviews existing remote sensing methods of road damage detection and demonstrates the possibility of using DInSAR (Differential Interferometry SAR) method to identify endangered road sections. In this study two radar images collected by Sentinel-1 satellite have been used. Images were acquired with 24 days interval in 2015. The analysis allowed to estimate the scale of the post-mining deformation that occurred in Upper Silesia and to indicate areas where road infrastructure is particularly vulnerable to damage.

An Element Free Galerkin method for an elastoplastic coupled to damage analysis

Directory of Open Access Journals (Sweden)

Sendi Zohra

2016-01-01

Full Text Available In this work, a Meshless approach for nonlinear solid mechanics is developed based on the Element Free Galerkin method. Furthermore, Meshless is combined with an elastoplastic model coupled to ductile damage. The efficiency of the proposed methodology is evaluated through various numerical examples. Besides these, two-dimensional tensile tests under several boundary conditions were studied and solved by a Dynamic-Explicit resolution scheme. Finally, the results obtained from the numerical simulations are analyzed and critically compared with Finite Element Method results.

Parameter Identification of Ship Maneuvering Models Using Recursive Least Square Method Based on Support Vector Machines

Directory of Open Access Journals (Sweden)

Man Zhu

2017-03-01

Full Text Available Determination of ship maneuvering models is a tough task of ship maneuverability prediction. Among several prime approaches of estimating ship maneuvering models, system identification combined with the full-scale or free- running model test is preferred. In this contribution, real-time system identification programs using recursive identification method, such as the recursive least square method (RLS, are exerted for on-line identification of ship maneuvering models. However, this method seriously depends on the objects of study and initial values of identified parameters. To overcome this, an intelligent technology, i.e., support vector machines (SVM, is firstly used to estimate initial values of the identified parameters with finite samples. As real measured motion data of the Mariner class ship always involve noise from sensors and external disturbances, the zigzag simulation test data include a substantial quantity of Gaussian white noise. Wavelet method and empirical mode decomposition (EMD are used to filter the data corrupted by noise, respectively. The choice of the sample number for SVM to decide initial values of identified parameters is extensively discussed and analyzed. With de-noised motion data as input-output training samples, parameters of ship maneuvering models are estimated using RLS and SVM-RLS, respectively. The comparison between identification results and true values of parameters demonstrates that both the identified ship maneuvering models from RLS and SVM-RLS have reasonable agreements with simulated motions of the ship, and the increment of the sample for SVM positively affects the identification results. Furthermore, SVM-RLS using data de-noised by EMD shows the highest accuracy and best convergence.

A Novel Complementary Method for the Point-Scan Nondestructive Tests Based on Lamb Waves

Directory of Open Access Journals (Sweden)

Rahim Gorgin

2014-01-01

Full Text Available This study presents a novel area-scan damage identification method based on Lamb waves which can be used as a complementary method for point-scan nondestructive techniques. The proposed technique is able to identify the most probable locations of damages prior to point-scan test which lead to decreasing the time and cost of inspection. The test-piece surface was partitioned with some smaller areas and the damage probability presence of each area was evaluated. A0 mode of Lamb wave was generated and collected using a mobile handmade transducer set at each area. Subsequently, a damage presence probability index (DPPI based on the energy of captured responses was defined for each area. The area with the highest DPPI value highlights the most probable locations of damages in test-piece. Point-scan nondestructive methods can then be used once these areas are found to identify the damage in detail. The approach was validated by predicting the most probable locations of representative damages including through-thickness hole and crack in aluminum plates. The obtained experimental results demonstrated the high potential of developed method in defining the most probable locations of damages in structures.

Hypertensive retinopathy identification through retinal fundus image using backpropagation neural network

Science.gov (United States)

Syahputra, M. F.; Amalia, C.; Rahmat, R. F.; Abdullah, D.; Napitupulu, D.; Setiawan, M. I.; Albra, W.; Nurdin; Andayani, U.

2018-03-01

Hypertension or high blood pressure can cause damage of blood vessels in the retina of eye called hypertensive retinopathy (HR). In the event Hypertension, it will cause swelling blood vessels and a decrese in retina performance. To detect HR in patients body, it is usually performed through physical examination of opthalmoscope which is still conducted manually by an ophthalmologist. Certainly, in such a manual manner, takes a ong time for a doctor to detetct HR on aa patient based on retina fundus iamge. To overcome ths problem, a method is needed to identify the image of retinal fundus automatically. In this research, backpropagation neural network was used as a method for retinal fundus identification. The steps performed prior to identification were pre-processing (green channel, contrast limited adapative histogram qualization (CLAHE), morphological close, background exclusion, thresholding and connected component analysis), feature extraction using zoning. The results show that the proposed method is able to identify retinal fundus with an accuracy of 95% with maximum epoch of 1500.

Identification Method of Mud Shale Fractures Base on Wavelet Transform

Science.gov (United States)

Xia, Weixu; Lai, Fuqiang; Luo, Han

2018-01-01

In recent years, inspired by seismic analysis technology, a new method for analysing mud shale fractures oil and gas reservoirs by logging properties has emerged. By extracting the high frequency attribute of the wavelet transform in the logging attribute, the formation information hidden in the logging signal is extracted, identified the fractures that are not recognized by conventional logging and in the identified fracture segment to show the “cycle jump”, “high value”, “spike” and other response effect is more obvious. Finally formed a complete wavelet denoising method and wavelet high frequency identification fracture method.

Feasibility Study on Tension Estimation Technique for Hanger Cables Using the FE Model-Based System Identification Method

Directory of Open Access Journals (Sweden)

Kyu-Sik Park

2015-01-01

Full Text Available Hanger cables in suspension bridges are partly constrained by horizontal clamps. So, existing tension estimation methods based on a single cable model are prone to higher errors as the cable gets shorter, making it more sensitive to flexural rigidity. Therefore, inverse analysis and system identification methods based on finite element models are suggested recently. In this paper, the applicability of system identification methods is investigated using the hanger cables of Gwang-An bridge. The test results show that the inverse analysis and systemic identification methods based on finite element models are more reliable than the existing string theory and linear regression method for calculating the tension in terms of natural frequency errors. However, the estimation error of tension can be varied according to the accuracy of finite element model in model based methods. In particular, the boundary conditions affect the results more profoundly when the cable gets shorter. Therefore, it is important to identify the boundary conditions through experiment if it is possible. The FE model-based tension estimation method using system identification method can take various boundary conditions into account. Also, since it is not sensitive to the number of natural frequency inputs, the availability of this system is high.

On-the-spot damage detection methodology for highway bridges.

Science.gov (United States)

2010-07-01

Vibration-based damage identification (VBDI) techniques have been developed in part to address the problems associated with an aging civil infrastructure. To assess the potential of VBDI as it applies to highway bridges in Iowa, three applications of...

Application of a value-based equivalency method to assess environmental damage compensation under the European Environmental Liability Directive

NARCIS (Netherlands)

Martin-Ortega, J.; Brouwer, R.; Aiking, H.

2011-01-01

The Environmental Liability Directive (ELD) establishes a framework of liability based on the 'polluter-pays' principle to prevent and remedy environmental damage. The ELD requires the testing of appropriate equivalency methods to assess the scale of compensatory measures needed to offset damage.

Recognition of Damaged Arrow-Road Markings by Visible Light Camera Sensor Based on Convolutional Neural Network

Directory of Open Access Journals (Sweden)

Husan Vokhidov

2016-12-01

Full Text Available Automobile driver information as displayed on marked road signs indicates the state of the road, traffic conditions, proximity to schools, etc. These signs are important to insure the safety of the driver and pedestrians. They are also important input to the automated advanced driver assistance system (ADAS, installed in many automobiles. Over time, the arrow-road markings may be eroded or otherwise damaged by automobile contact, making it difficult for the driver to correctly identify the marking. Failure to properly identify an arrow-road marker creates a dangerous situation that may result in traffic accidents or pedestrian injury. Very little research exists that studies the problem of automated identification of damaged arrow-road marking painted on the road. In this study, we propose a method that uses a convolutional neural network (CNN to recognize six types of arrow-road markings, possibly damaged, by visible light camera sensor. Experimental results with six databases of Road marking dataset, KITTI dataset, Málaga dataset 2009, Málaga urban dataset, Naver street view dataset, and Road/Lane detection evaluation 2013 dataset, show that our method outperforms conventional methods.

Recognition of Damaged Arrow-Road Markings by Visible Light Camera Sensor Based on Convolutional Neural Network.

Science.gov (United States)

Vokhidov, Husan; Hong, Hyung Gil; Kang, Jin Kyu; Hoang, Toan Minh; Park, Kang Ryoung

2016-12-16

Automobile driver information as displayed on marked road signs indicates the state of the road, traffic conditions, proximity to schools, etc. These signs are important to insure the safety of the driver and pedestrians. They are also important input to the automated advanced driver assistance system (ADAS), installed in many automobiles. Over time, the arrow-road markings may be eroded or otherwise damaged by automobile contact, making it difficult for the driver to correctly identify the marking. Failure to properly identify an arrow-road marker creates a dangerous situation that may result in traffic accidents or pedestrian injury. Very little research exists that studies the problem of automated identification of damaged arrow-road marking painted on the road. In this study, we propose a method that uses a convolutional neural network (CNN) to recognize six types of arrow-road markings, possibly damaged, by visible light camera sensor. Experimental results with six databases of Road marking dataset, KITTI dataset, Málaga dataset 2009, Málaga urban dataset, Naver street view dataset, and Road/Lane detection evaluation 2013 dataset, show that our method outperforms conventional methods.

Recognition of Damaged Arrow-Road Markings by Visible Light Camera Sensor Based on Convolutional Neural Network

Science.gov (United States)

Vokhidov, Husan; Hong, Hyung Gil; Kang, Jin Kyu; Hoang, Toan Minh; Park, Kang Ryoung

2016-01-01

Automobile driver information as displayed on marked road signs indicates the state of the road, traffic conditions, proximity to schools, etc. These signs are important to insure the safety of the driver and pedestrians. They are also important input to the automated advanced driver assistance system (ADAS), installed in many automobiles. Over time, the arrow-road markings may be eroded or otherwise damaged by automobile contact, making it difficult for the driver to correctly identify the marking. Failure to properly identify an arrow-road marker creates a dangerous situation that may result in traffic accidents or pedestrian injury. Very little research exists that studies the problem of automated identification of damaged arrow-road marking painted on the road. In this study, we propose a method that uses a convolutional neural network (CNN) to recognize six types of arrow-road markings, possibly damaged, by visible light camera sensor. Experimental results with six databases of Road marking dataset, KITTI dataset, Málaga dataset 2009, Málaga urban dataset, Naver street view dataset, and Road/Lane detection evaluation 2013 dataset, show that our method outperforms conventional methods. PMID:27999301

Process identification method based on the Z transformation

International Nuclear Information System (INIS)

Zwingelstein, G.

1968-01-01

A simple method is described for identifying the transfer function of a linear retard-less system, based on the inversion of the Z transformation of the transmittance using a computer. It is assumed in this study that the signals at the entrance and at the exit of the circuit considered are of the deterministic type. The study includes: the theoretical principle of the inversion of the Z transformation, details about programming simulation, and identification of filters whose degrees vary from the first to the fifth order. (authors) [fr

Denture identification using unique identification authority of India barcode

OpenAIRE

Sudhindra Mahoorkar; Anoop Jain

2013-01-01

Over the years, various denture marking systems have been reported in the literature for personal identification. They have been broadly divided into surface marking and inclusion methods. In this technique, patient's unique identification number and barcode printed in the patient's Aadhaar card issued by Unique Identification Authority of India (UIDAI) are used as denture markers. This article describes a simple, quick, and economical method for identification of individual.

Denture identification using unique identification authority of India barcode.

Science.gov (United States)

Mahoorkar, Sudhindra; Jain, Anoop

2013-01-01

Over the years, various denture marking systems have been reported in the literature for personal identification. They have been broadly divided into surface marking and inclusion methods. In this technique, patient's unique identification number and barcode printed in the patient's Aadhaar card issued by Unique Identification Authority of India (UIDAI) are used as denture markers. This article describes a simple, quick, and economical method for identification of individual.

Haertel's turbidity test and extraction of conifer needles by benzene as methods for the determination of smoke-induced damage

Energy Technology Data Exchange (ETDEWEB)

Materna, J; Hrncirova, L

1960-01-01

The applicability of the Haertel turbidity test to the assessment of smoke damage to conifers is based on the observation that needles from smoke damage to conifers is based on the observation that needles from smoke-damaged areas eliminate less wax than undamaged needles. Of the various organic solvent and extraction methods tested, best results were obtained by a half-hour extraction of the wax from the needle surface with cold benzene. The evaporation residue from this extraction method contained only traces of components from the inside of the needles; microscopic examination of the surface of the needles revealed that all wax was removed from the needle surface fissures. Comparison of wax quantities extracted from needles from smoke-damage areas with those from healthy needles and comparison of wax yields from areas which suffered different degrees of smoke damage confirmed that higher wax yields are obtained from healthy than from smoke-damaged needles. Comparison with results of turbidity tests disclosed that benzene extraction yields decreased with increasing turbidity test values, indicating that increased turbidity of smoke-damaged needles is not caused by wax. In the Haertel test extract, silicon, calcium, magnesium, phosphorus, potassium, sulfur, iron, nitrogenous substances, tannin, glycides, and waxes were found. It is as yet unresolved which substances contribute to increased turbidity from smoke damage.

An Applied Method for Predicting the Load-Carrying Capacity in Compression of Thin-Wall Composite Structures with Impact Damage

Science.gov (United States)

Mitrofanov, O.; Pavelko, I.; Varickis, S.; Vagele, A.

2018-03-01

The necessity for considering both strength criteria and postbuckling effects in calculating the load-carrying capacity in compression of thin-wall composite structures with impact damage is substantiated. An original applied method ensuring solution of these problems with an accuracy sufficient for practical design tasks is developed. The main advantage of the method is its applicability in terms of computing resources and the set of initial data required. The results of application of the method to solution of the problem of compression of fragments of thin-wall honeycomb panel damaged by impacts of various energies are presented. After a comparison of calculation results with experimental data, a working algorithm for calculating the reduction in the load-carrying capacity of a composite object with impact damage is adopted.

Damage development in 9%Cr steels

International Nuclear Information System (INIS)

Rauch, M.; Maile, K.

2003-01-01

Modern 9-11% martensitic steels are candidate materials to be used in modern fossil fired power plants with high efficiency rates. The focus of the R and D work is put on the further development and optimisation, the determination of material characteristics but also on the identification and quantification of damage mechanisms and the damage evolution. For this purpose extensive experiments such as long creep tests on specimens under internal pressure, metallurgical examinations and theoretical investigations for determination of stress-strain state which have been conducted. The laboratory tests are completed by examination of real components. As a result an empirical description of the creep cavity density as a function of deformation and multiaxiality of stress state has been carried out which can be used in further FE-calculations determining the damage state. The results of all metallographical examinations on specimens with different heat treatments and service loads are summarised in a structure atlas and are published for further usage. Damage development, martensitic 9 % Cr steels, creep cavity density, creep tests under multiaxial load, metallographical investigations, and measurements on pipe bends. (author)

Microbiological method for radiation sterilization (I). General knowledge and handling technique for bacterial identification

International Nuclear Information System (INIS)

Koshikawa, Tomihiko

2004-01-01

The part I in this title series describes the basic knowledge and technique for identification of bacteria in the radiation sterilization of medical devices, where the radiation dose can be decided from the number and radio-resistance of the bioburden (bacteria on the device). Four essential, actual technologies for identification are described: isolation and storage of bacteria; decision of bacterial natures, involving 3 Gram staining methods, morphology by microscopy and/or phase-contrast microscopy, spore-forming bacteria, and size measurement by micrometry; Other test items for identification of genus, involving motility, oxygen demand, catalase, oxidase, acid production from glucose, and OF (oxidation or fermentation for glucose degradation) test; and colony observation. Media, identification kits and record forms for these are presented. (N.I.)

On the modal characteristics of damaging structures subjected to earthquakes

Science.gov (United States)

Carlo Ponzo, Felice; Ditommaso, Rocco; Auletta, Gianluca; Iacovino, Chiara; Mossucca, Antonello; Nigro, Antonella; Nigro, Domenico

2015-04-01

Structural Health Monitoring, especially for structures located in seismic prone areas, has assumed a meaning of great importance in last years, for the possibility to make a more objective and more rapid estimation of the damage occurred on buildings after a seismic event. In the last years many researchers are working to set-up new methodologies for Non-destructive Damage Evaluation based on the variation of the dynamic behaviour of structures under seismic loads. The NDE methods for damage detection and evaluation can be classified into four levels, according to the specific criteria provided by the Rytter. Each level of identification is correlated with specific information related to monitored structure. In fact, by increasing the level it is possible to obtain more information about the state of the health of the structures, to know if damage occurred on the structures, to quantify and localize the damage and to evaluate its impact on the monitored structure. Several authors discussed on the possibility to use the mode shape curvature to localize damage on structural elements, for example, by applying the curvature-based method to frequency response function instead of mode shape, and demonstrated the potential of this approach by considering real data. Damage detection approach based on dynamic monitoring of structural properties over time has received a considerable attention in recent scientific literature. In earthquake engineering field, the recourse to experimental research is necessary to understand the mechanical behaviour of the various structural and non-structural components. In this paper a new methodology to detect and localize a possible damage occurred on a framed structure after an earthquake is presented and discussed. The main outcomes retrieved from many numerical non linear dynamic models of reinforced concrete framed structures characterized by 3, 5 and 8 floors with different geometric configurations and designed for gravity loads only

Benchmarking of methods for identification of antimicrobial resistance genes in bacterial whole genome data

DEFF Research Database (Denmark)

Clausen, Philip T. L. C.; Zankari, Ea; Aarestrup, Frank Møller

2016-01-01

to two different methods in current use for identification of antibiotic resistance genes in bacterial WGS data. A novel method, KmerResistance, which examines the co-occurrence of k-mers between the WGS data and a database of resistance genes, was developed. The performance of this method was compared...... with two previously described methods; ResFinder and SRST2, which use an assembly/BLAST method and BWA, respectively, using two datasets with a total of 339 isolates, covering five species, originating from the Oxford University Hospitals NHS Trust and Danish pig farms. The predicted resistance...... was compared with the observed phenotypes for all isolates. To challenge further the sensitivity of the in silico methods, the datasets were also down-sampled to 1% of the reads and reanalysed. The best results were obtained by identification of resistance genes by mapping directly against the raw reads...

A method for crack profiles identification in eddy current testing by the multi-directional scan

International Nuclear Information System (INIS)

Kojima, Fumio; Ikeda, Takuya; Nguyen, Doung

2006-01-01

This paper is concerned with a method for identification of crack shape in conducting materials. Multi-directional scanning strategies using Eddy Current Testing is performed for sizing complex natural crackings. Two dimensional measurements by means of multi-directional scan are used in a output least square identifications. (author)

A measurement fusion method for nonlinear system identification using a cooperative learning algorithm.

Science.gov (United States)

Xia, Youshen; Kamel, Mohamed S

2007-06-01

Identification of a general nonlinear noisy system viewed as an estimation of a predictor function is studied in this article. A measurement fusion method for the predictor function estimate is proposed. In the proposed scheme, observed data are first fused by using an optimal fusion technique, and then the optimal fused data are incorporated in a nonlinear function estimator based on a robust least squares support vector machine (LS-SVM). A cooperative learning algorithm is proposed to implement the proposed measurement fusion method. Compared with related identification methods, the proposed method can minimize both the approximation error and the noise error. The performance analysis shows that the proposed optimal measurement fusion function estimate has a smaller mean square error than the LS-SVM function estimate. Moreover, the proposed cooperative learning algorithm can converge globally to the optimal measurement fusion function estimate. Finally, the proposed measurement fusion method is applied to ARMA signal and spatial temporal signal modeling. Experimental results show that the proposed measurement fusion method can provide a more accurate model.

The Art of Intraoperative Glioma Identification

Directory of Open Access Journals (Sweden)

Zoe Z Zhang

2015-07-01

Full Text Available A major dilemma in brain tumor surgery is the identification of tumor boundaries to maximize tumor excision and minimize postoperative neurological damage. Gliomas, especially low-grade tumors, and normal brain have a similar color and texture which poses a challenge to the neurosurgeon. Advances in glioma resection techniques combine the experience of the neurosurgeon and various advanced technologies. Intraoperative methods to delineate gliomas from normal tissue consist of 1 image-based navigation, 2 intraoperative sampling, 3 electrophysiological monitoring, and 4 enhanced visual tumor demarcation. The advantages and disadvantages of each technique are discussed. A combination of these methods is becoming widely accepted in routine glioma surgery. Gross total resection in conjunction with radiation, chemotherapy, or immune/gene therapy may increase the rates of cure in this devastating disease.

An identification method for damping ratio in rotor systems

Science.gov (United States)

Wang, Weimin; Li, Qihang; Gao, Jinji; Yao, Jianfei; Allaire, Paul

2016-02-01

Centrifugal compressor testing with magnetic bearing excitations is the last step to assure the compressor rotordynamic stability in the designed operating conditions. To meet the challenges of stability evaluation, a new method combining the rational polynomials method (RPM) with the weighted instrumental variables (WIV) estimator to fit the directional frequency response function (dFRF) is presented. Numerical simulation results show that the method suggested in this paper can identify the damping ratio of the first forward and backward modes with high accuracy, even in a severe noise environment. Experimental tests were conducted to study the effect of different bearing configurations on the stability of rotor. Furthermore, two example centrifugal compressors (a nine-stage straight-through and a six-stage back-to-back) were employed to verify the feasibility of identification method in industrial configurations as well.

The power grid AGC frequency bias coefficient online identification method based on wide area information

Science.gov (United States)

Wang, Zian; Li, Shiguang; Yu, Ting

2015-12-01

This paper propose online identification method of regional frequency deviation coefficient based on the analysis of interconnected grid AGC adjustment response mechanism of regional frequency deviation coefficient and the generator online real-time operation state by measured data through PMU, analyze the optimization method of regional frequency deviation coefficient in case of the actual operation state of the power system and achieve a more accurate and efficient automatic generation control in power system. Verify the validity of the online identification method of regional frequency deviation coefficient by establishing the long-term frequency control simulation model of two-regional interconnected power system.

A damage cumulation method for crack initiation prediction under non proportional loading and overloading

International Nuclear Information System (INIS)

Taheri, S.

1992-04-01

For a sequence of constant amplitude cyclic loading containing overloads, we propose a method for damage cumulation in non proportional loading. This method uses as data cyclic stabilized states at non proportional loading and initiation or fatigue curve in uniaxial case. For that, we take into account the dependence of Cyclic Strain Stress Curves (C.S.S.C.) and mean cell size on prehardening and we define a stabilized uniaxial state cyclically equivalent to a non proportional stabilized state through a family of C.S.S.C. Although simple assumptions like linear damage function and linear cumulation is used we obtain a sequence effect for difficult cross slip materials as 316 stainless steel, but the Miner rule for easy cross-slip materials. We show then differences between a load-controlled test and a strain controlled test: for a 316 stainless steel in a load controlled test, the non proportional loading at each cycle is less damaging than the uniaxial one for the same equivalent stress, while the result is opposite in a strain controlled test. We show also that an overloading retards initiation in a load controlled test while it accelerates initiation in a strain controlled test. (author). 26 refs., 8 figs

Tomography reconstruction methods for damage diagnosis of wood structure in construction field

Science.gov (United States)

Qiu, Qiwen; Lau, Denvid

2018-03-01

The structural integrity of wood building element plays a critical role in the public safety, which requires effective methods for diagnosis of internal damage inside the wood body. Conventionally, the non-destructive testing (NDT) methods such as X-ray computed tomography, thermography, radar imaging reconstruction method, ultrasonic tomography, nuclear magnetic imaging techniques, and sonic tomography have been used to obtain the information about the internal structure of wood. In this paper, the applications, advantages and disadvantages of these traditional tomography methods are reviewed. Additionally, the present article gives an overview of recently developed tomography approach that relies on the use of mechanical and electromagnetic waves for assessing the structural integrity of wood buildings. This developed tomography reconstruction method is believed to provide a more accurate, reliable, and comprehensive assessment of wood structural integrity

Strategy for identification & characterization of Bartonella henselae with conventional & molecular methods

Directory of Open Access Journals (Sweden)

Kavita Diddi

2013-01-01

Full Text Available Background & objectives: Bartonella henselae is a fastidious gram-negative bacterium usually causing self limiting infections in immunocompetent individuals but often causes potentially life threatening infection, such as bacillary angiomatosis in immunocompromised patients. Both diagnosis of infections and research into molecular mechanisms of pathogenesis have been hindered by lack of appropriate and reliable diagnostic techniques. We undertook this study to standardize methods to characterize B. henselae in clinical samples to diagnose Bartonella infection correctly. Methods: B. henselae ATCC 49882 strain was procured from American type culture collection, USA. This strain was revived and maintained in the laboratory, and identification and characterization of this strain was done by conventional and molecular techniques, which included culture on various media, staining by different methods including electron microscopy, biochemical analysis by conventional methods and API, polymerase chain reaction (PCR for amplification of citrate synthase gene followed by restriction fragment length polymorphism (RFLP. Results: This organism was biochemically inert due to slow growth and generated unique identification code with API. The amplification of the citrate-synthase gene with primers yielded a 381 bp product followed by specific RFLP profile for B. henselae. Interpretation & conclusions: Bartonella is fastidious and fragile organism and should be handled carefully. Extra effort and careful observation are required to isolate and characterize this organism.

A pattern recognition approach based on DTW for automatic transient identification in nuclear power plants

International Nuclear Information System (INIS)

Galbally, Javier; Galbally, David

2015-01-01

Highlights: • Novel transient identification method for NPPs. • Low-complexity. • Low training data requirements. • High accuracy. • Fully reproducible protocol carried out on a real benchmark. - Abstract: Automatic identification of transients in nuclear power plants (NPPs) allows monitoring the fatigue damage accumulated by critical components during plant operation, and is therefore of great importance for ensuring that usage factors remain within the original design bases postulated by the plant designer. Although several schemes to address this important issue have been explored in the literature, there is still no definitive solution available. In the present work, a new method for automatic transient identification is proposed, based on the Dynamic Time Warping (DTW) algorithm, largely used in other related areas such as signature or speech recognition. The novel transient identification system is evaluated on real operational data following a rigorous pattern recognition protocol. Results show the high accuracy of the proposed approach, which is combined with other interesting features such as its low complexity and its very limited requirements of training data

An elastic-visco-plastic damage model: from theory to application

International Nuclear Information System (INIS)

Wang, X.C.; Habraken, A.M.

1996-01-01

An energy-based two-variable damage theory is applied to Bodner's model. It gives an elastic-viscoplastic damage model. Some theoretical details are described in this paper. The parameters identification procedure is discussed and a complete set of parameters for an aluminium is presented. Numerical modelling of the laboratory tests are used to validate the model. An industrial aeronautic rod fabrication process is simulated and some numerical results are presented in this paper. (orig.)

Comparison of residual strength-grounding damage index diagrams for tankers produced by the ALPS/HULL ISFEM and design formula method

Directory of Open Access Journals (Sweden)

Do Kyun Kim

2013-03-01

Full Text Available This study compares the Residual ultimate longitudinal strength – grounding Damage index (R-D diagrams produced by two analysis methods: the ALPS/HULL Intelligent Supersize Finite Element Method (ISFEM and the design formula (modified Paik and Mansour method – used to assess the safety of damaged ships. The comparison includes four types of double-hull oil tankers: Panamax, Aframax, Suezmax and VLCC. The R-D diagrams were calculated for a series of 50 grounding scenarios. The diagrams were efficiently sampled using the Latin Hypercube Sampling (LHS technique and comprehensively analysed based on ship size. Finally, the two methods were compared by statistically analysing the differences between their grounding damage indices and ultimate longitudinal strength predictions. The findings provide a useful example of how to apply the ultimate longitudinal strength analysis method to grounded ships.

The identification of carbide phases by XRD analysis as the method of assess the extent of the steel damage after long time in service

Directory of Open Access Journals (Sweden)

I. Pietryka

2010-07-01

Full Text Available After long time in service in contact in a superheated steam mechanical properties of materials decrease. Experiments revealed that the XRD analysis of electrocemically separated carbide phase is a rapid and informative method of evaluation the service condition of steel. Mechanical properties of ferritic and bainitic low-alloy steels are caused by many factors like: chemical composition, quantity and the kind of microstructural constituent, the precipitation hardening, substructure of matrix and index of matrix lattice defects. In this paper the results of investigations 13CrMo4-5 steel was shown. The material for research was taken from thermal power plant elements. Material A was after 150.000 hours of work as the pressure chamber in which was the temperature 530-580oC and the pressure was 12 MPa. Material B was after 250000 hours of work as the pipeline of superheated steam. The temperature in this case was 530oC but the pressure was 12 MPa as well. The mechanical properties after long time service and changes in fine structure were tested. Parameters of carbide phase electrochemical separation in electrolytes solutions are presented in this work.The most relevant electrolyte and the far better conditions of extraction process were chosen taking into consideration the time needed to get considerable amount of carbide phase constituents. The identification of carbide phases was the special goal of this work. Identification of electrochemically separated carbide phases by means of the XRD analysis was used.

Review on applied foods and analyzed methods in identification testing of irradiated foods

International Nuclear Information System (INIS)

Kim, Kwang Hoon; Lee, Hoo Chul; Park, Sung Hyun; Kim, Soo Jin; Kim, Kwan Soo; Jeong, Il Yun; Lee, Ju Woon; Yook, Hong Sun

2010-01-01

Identification methods of irradiated foods have been adopted as official test by EU and Codex. PSL, TL, ESR and GC/MS methods were registered in Korea food code on 2009 and put in force as control system of verification for labelling of food irradiation. But most generally applicable PSL and TL methods are specified applicable foods according to domestic approved items. Unlike these specifications, foods unpermitted in Korea are included in applicable items of ESR and GC/MS methods. According to recent research data, numerous food groups are possible to effective legal control by identification and these items are demanded to permit regulations for irradiation additionally. Especially, the prohibition of irradiation for meats or seafoods is not harmonized with international standards and interacts as trade friction or industrial restrictions due to unprepared domestic regulation. Hence, extension of domestic legal permission for food irradiation can contrive to related industrial development and also can reduce trade friction and enhance international competitiveness

ITPI: Initial Transcription Process-Based Identification Method of Bioactive Components in Traditional Chinese Medicine Formula

Directory of Open Access Journals (Sweden)

Baixia Zhang

2016-01-01

Full Text Available Identification of bioactive components is an important area of research in traditional Chinese medicine (TCM formula. The reported identification methods only consider the interaction between the components and the target proteins, which is not sufficient to explain the influence of TCM on the gene expression. Here, we propose the Initial Transcription Process-based Identification (ITPI method for the discovery of bioactive components that influence transcription factors (TFs. In this method, genome-wide chip detection technology was used to identify differentially expressed genes (DEGs. The TFs of DEGs were derived from GeneCards. The components influencing the TFs were derived from STITCH. The bioactive components in the formula were identified by evaluating the molecular similarity between the components in formula and the components that influence the TF of DEGs. Using the formula of Tian-Zhu-San (TZS as an example, the reliability and limitation of ITPI were examined and 16 bioactive components that influence TFs were identified.

Identification of ATM Protein Kinase Phosphorylation Sites by Mass Spectrometry.

Science.gov (United States)

Graham, Mark E; Lavin, Martin F; Kozlov, Sergei V

2017-01-01

ATM (ataxia-telangiectasia mutated) protein kinase is a key regulator of cellular responses to DNA damage and oxidative stress. DNA damage triggers complex cascade of signaling events leading to numerous posttranslational modification on multitude of proteins. Understanding the regulation of ATM kinase is therefore critical not only for understanding the human genetic disorder ataxia-telangiectasia and potential treatment strategies, but essential for deciphering physiological responses of cells to stress. These responses play an important role in carcinogenesis, neurodegeneration, and aging. We focus here on the identification of DNA damage inducible ATM phosphorylation sites to understand the importance of autophosphorylation in the mechanism of ATM kinase activation. We demonstrate the utility of using immunoprecipitated ATM in quantitative LC-MS/MS workflow with stable isotope dimethyl labeling of ATM peptides for identification of phosphorylation sites.

Frequency domain fatigue damage estimation methods suitable for deterministic load spectra

Energy Technology Data Exchange (ETDEWEB)

Henderson, A.R.; Patel, M.H. [University Coll., Dept. of Mechanical Engineering, London (United Kingdom)

2000-07-01

The evaluation of fatigue damage due to load spectra, directly in the frequency domain, is a complex phenomena but with the benefit of significant computation time savings. Various formulae have been suggested but have usually relating to a specific application only. The Dirlik method is the exception and is applicable to general cases of continuous stochastic spectra. This paper describes three approaches for evaluating discrete deterministic load spectra generated by the floating wind turbine model developed the UCL/RAL research project. (Author)

A Review of Spectral Methods for Variable Amplitude Fatigue Prediction and New Results

Science.gov (United States)

Larsen, Curtis E.; Irvine, Tom

2013-01-01

A comprehensive review of the available methods for estimating fatigue damage from variable amplitude loading is presented. The dependence of fatigue damage accumulation on power spectral density (psd) is investigated for random processes relevant to real structures such as in offshore or aerospace applications. Beginning with the Rayleigh (or narrow band) approximation, attempts at improved approximations or corrections to the Rayleigh approximation are examined by comparison to rainflow analysis of time histories simulated from psd functions representative of simple theoretical and real world applications. Spectral methods investigated include corrections by Wirsching and Light, Ortiz and Chen, the Dirlik formula, and the Single-Moment method, among other more recent proposed methods. Good agreement is obtained between the spectral methods and the time-domain rainflow identification for most cases, with some limitations. Guidelines are given for using the several spectral methods to increase confidence in the damage estimate.

Signal trend identification with fuzzy methods

International Nuclear Information System (INIS)

Reifman, J.; Tsoukalas, L. H.; Wang, X.; Wei, T. Y. C.

1999-01-01

A fuzzy-logic-based methodology for on-line signal trend identification is introduced. Although signal trend identification is complicated by the presence of noise, fuzzy logic can help capture important features of on-line signals and classify incoming power plant signals into increasing, decreasing and steady-state trend categories. In order to verify the methodology, a code named PROTREN is developed and tested using plant data. The results indicate that the code is capable of detecting transients accurately, identifying trends reliably, and not misinterpreting a steady-state signal as a transient one

Comparison Study of Subspace Identification Methods Applied to Flexible Structures

Science.gov (United States)

Abdelghani, M.; Verhaegen, M.; Van Overschee, P.; De Moor, B.

1998-09-01

In the past few years, various time domain methods for identifying dynamic models of mechanical structures from modal experimental data have appeared. Much attention has been given recently to so-called subspace methods for identifying state space models. This paper presents a detailed comparison study of these subspace identification methods: the eigensystem realisation algorithm with observer/Kalman filter Markov parameters computed from input/output data (ERA/OM), the robust version of the numerical algorithm for subspace system identification (N4SID), and a refined version of the past outputs scheme of the multiple-output error state space (MOESP) family of algorithms. The comparison is performed by simulating experimental data using the five mode reduced model of the NASA Mini-Mast structure. The general conclusion is that for the case of white noise excitations as well as coloured noise excitations, the N4SID/MOESP algorithms perform equally well but give better results (improved transfer function estimates, improved estimates of the output) compared to the ERA/OM algorithm. The key computational step in the three algorithms is the approximation of the extended observability matrix of the system to be identified, for N4SID/MOESP, or of the observer for the system to be identified, for the ERA/OM. Furthermore, the three algorithms only require the specification of one dimensioning parameter.

Wireless and real-time structural damage detection: A novel decentralized method for wireless sensor networks

Science.gov (United States)

Avci, Onur; Abdeljaber, Osama; Kiranyaz, Serkan; Hussein, Mohammed; Inman, Daniel J.

2018-06-01

Being an alternative to conventional wired sensors, wireless sensor networks (WSNs) are extensively used in Structural Health Monitoring (SHM) applications. Most of the Structural Damage Detection (SDD) approaches available in the SHM literature are centralized as they require transferring data from all sensors within the network to a single processing unit to evaluate the structural condition. These methods are found predominantly feasible for wired SHM systems; however, transmission and synchronization of huge data sets in WSNs has been found to be arduous. As such, the application of centralized methods with WSNs has been a challenge for engineers. In this paper, the authors are presenting a novel application of 1D Convolutional Neural Networks (1D CNNs) on WSNs for SDD purposes. The SDD is successfully performed completely wireless and real-time under ambient conditions. As a result of this, a decentralized damage detection method suitable for wireless SHM systems is proposed. The proposed method is based on 1D CNNs and it involves training an individual 1D CNN for each wireless sensor in the network in a format where each CNN is assigned to process the locally-available data only, eliminating the need for data transmission and synchronization. The proposed damage detection method operates directly on the raw ambient vibration condition signals without any filtering or preprocessing. Moreover, the proposed approach requires minimal computational time and power since 1D CNNs merge both feature extraction and classification tasks into a single learning block. This ability is prevailingly cost-effective and evidently practical in WSNs considering the hardware systems have been occasionally reported to suffer from limited power supply in these networks. To display the capability and verify the success of the proposed method, large-scale experiments conducted on a laboratory structure equipped with a state-of-the-art WSN are reported.

Radioisotope identification method for poorly resolved gamma-ray spectrum of nuclear security concern

Energy Technology Data Exchange (ETDEWEB)

Ninh, Giang Nguyen; Phongphaeth, Pengvanich, E-mail: phongphaeth.p@chula.ac.th; Nares, Chankow [Nuclear Engineering Department, Faculty of Engineering, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330 (Thailand); Hao, Quang Nguyen [Vietnam Atomic Energy Institute, Ministry of Science and Technology, Hanoi (Viet Nam)

2016-01-22

Gamma-ray signal can be used as a fingerprint for radioisotope identification. In the context of radioactive and nuclear materials security at the border control point, the detection task can present a significant challenge due to various constraints such as the limited measurement time, the shielding conditions, and the noise interference. This study proposes a novel method to identify the signal of one or several radioisotopes from a poorly resolved gamma-ray spectrum. In this method, the noise component in the raw spectrum is reduced by the wavelet decomposition approach, and the removal of the continuum background is performed using the baseline determination algorithm. Finally, the identification of radioisotope is completed using the matrix linear regression method. The proposed method has been verified by experiments using the poorly resolved gamma-ray signals from various scenarios including single source, mixing of natural uranium with five of the most common industrial radioactive sources (57Co, 60Co, 133Ba, 137Cs, and 241Am). The preliminary results show that the proposed algorithm is comparable with the commercial method.

Radioisotope identification method for poorly resolved gamma-ray spectrum of nuclear security concern

International Nuclear Information System (INIS)

Ninh, Giang Nguyen; Phongphaeth, Pengvanich; Nares, Chankow; Hao, Quang Nguyen

2016-01-01

Gamma-ray signal can be used as a fingerprint for radioisotope identification. In the context of radioactive and nuclear materials security at the border control point, the detection task can present a significant challenge due to various constraints such as the limited measurement time, the shielding conditions, and the noise interference. This study proposes a novel method to identify the signal of one or several radioisotopes from a poorly resolved gamma-ray spectrum. In this method, the noise component in the raw spectrum is reduced by the wavelet decomposition approach, and the removal of the continuum background is performed using the baseline determination algorithm. Finally, the identification of radioisotope is completed using the matrix linear regression method. The proposed method has been verified by experiments using the poorly resolved gamma-ray signals from various scenarios including single source, mixing of natural uranium with five of the most common industrial radioactive sources (57Co, 60Co, 133Ba, 137Cs, and 241Am). The preliminary results show that the proposed algorithm is comparable with the commercial method

Damaged Watermarks Detection in Frequency Domain as a Primary Method for Video Concealment

Directory of Open Access Journals (Sweden)

Robert Hudec

2011-01-01

Full Text Available This paper deals with video transmission over lossy communication networks. The main idea is to develop video concealment method for information losses and errors correction. At the beginning, three main groups of video concealment methods, divided by encoder/decoder collaboration, are briefly described. The modified algorithm based on the detection and filtration of damaged watermark blocks encapsulated to the transmitted video was developed. Finally, the efficiency of developed algorithm is presented in experimental part of this paper.

Measurement methods for high energy particle identification in gaseous mixture detectors

International Nuclear Information System (INIS)

Marchand, Patrick.

1981-01-01

In this work, we discuss some methods for high energy particle identification. We study and design a MWPC equipped with a preamplifier gap for increased resolution. In addition, we propose a new mehod of counting primary collisions. The electronic system used for multiplexing analog wire signals is also described [fr

A Reference-Free and Non-Contact Method for Detecting and Imaging Damage in Adhesive-Bonded Structures Using Air-Coupled Ultrasonic Transducers

Directory of Open Access Journals (Sweden)

Timotius Yonathan Sunarsa

2017-12-01

Full Text Available Adhesive bonded structures have been widely used in aerospace, automobile, and marine industries. Due to the complex nature of the failure mechanisms of bonded structures, cost-effective and reliable damage detection is crucial for these industries. Most of the common damage detection methods are not adequately sensitive to the presence of weakened bonding. This paper presents an experimental and analytical method for the in-situ detection of damage in adhesive-bonded structures. The method is fully non-contact, using air-coupled ultrasonic transducers (ACT for ultrasonic wave generation and sensing. The uniqueness of the proposed method relies on accurate detection and localization of weakened bonding in complex adhesive bonded structures. The specimens tested in this study are parts of real-world structures with critical and complex damage types, provided by Hyundai Heavy Industries® and IKTS Fraunhofer®. Various transmitter and receiver configurations, including through transmission, pitch-catch scanning, and probe holder angles, were attempted, and the obtained results were analyzed. The method examines the time-of-flight of the ultrasonic waves over a target inspection area, and the spatial variation of the time-of-flight information was examined to visualize and locate damage. The proposed method works without relying on reference data obtained from the pristine condition of the target specimen. Aluminum bonded plates and triplex adhesive layers with debonding and weakened bonding were used to examine the effectiveness of the method.

Nonlinear system identification NARMAX methods in the time, frequency, and spatio-temporal domains

CERN Document Server

Billings, Stephen A

2013-01-01

Nonlinear System Identification: NARMAX Methods in the Time, Frequency, and Spatio-Temporal Domains describes a comprehensive framework for the identification and analysis of nonlinear dynamic systems in the time, frequency, and spatio-temporal domains. This book is written with an emphasis on making the algorithms accessible so that they can be applied and used in practice. Includes coverage of: The NARMAX (nonlinear autoregressive moving average with exogenous inputs) modelThe orthogonal least squares algorithm that allows models to be built term by

Development of an ultrasonic nondestructive inspection method for impact damage detection in composite aircraft structures

Science.gov (United States)

Capriotti, M.; Kim, H. E.; Lanza di Scalea, F.; Kim, H.

2017-04-01

High Energy Wide Area Blunt Impact (HEWABI) due to ground service equipment can often occur in aircraft structures causing major damages. These Wide Area Impact Damages (WAID) can affect the internal components of the structure, hence are usually not visible nor detectable by typical one-sided NDE techniques and can easily compromise the structural safety of the aircraft. In this study, the development of an NDI method is presented together with its application to impacted aircraft frames. The HEWABI from a typical ground service scenario has been previously tested and the desired type of damages have been generated, so that the aircraft panels could become representative study cases. The need of the aircraft industry for a rapid, ramp-friendly system to detect such WAID is here approached with guided ultrasonic waves (GUW) and a scanning tool that accesses the whole structure from the exterior side only. The wide coverage of the specimen provided by GUW has been coupled to a differential detection approach and is aided by an outlier statistical analysis to be able to inspect and detect faults in the challenging composite material and complex structure. The results will be presented and discussed with respect to the detection capability of the system and its response to the different damage types. Receiving Operating Characteristics curves (ROC) are also produced to quantify and assess the performance of the proposed method. Ongoing work is currently aimed at the penetration of the inner components of the structure, such as shear ties and C-frames, exploiting different frequency ranges and signal processing techniques. From the hardware and tool development side, different transducers and coupling methods, such as air-coupled transducers, are under investigation together with the design of a more suitable scanning technique.

A Maximum Power Transfer Tracking Method for WPT Systems with Coupling Coefficient Identification Considering Two-Value Problem

Directory of Open Access Journals (Sweden)

Xin Dai

2017-10-01

Full Text Available Maximum power transfer tracking (MPTT is meant to track the maximum power point during the system operation of wireless power transfer (WPT systems. Traditionally, MPTT is achieved by impedance matching at the secondary side when the load resistance is varied. However, due to a loosely coupling characteristic, the variation of coupling coefficient will certainly affect the performance of impedance matching, therefore MPTT will fail accordingly. This paper presents an identification method of coupling coefficient for MPTT in WPT systems. Especially, the two-value issue during the identification is considered. The identification approach is easy to implement because it does not require additional circuit. Furthermore, MPTT is easy to realize because only two easily measured DC parameters are needed. The detailed identification procedure corresponding to the two-value issue and the maximum power transfer tracking process are presented, and both the simulation analysis and experimental results verified the identification method and MPTT.

On the orthogonalised reverse path method for nonlinear system identification

Science.gov (United States)

Muhamad, P.; Sims, N. D.; Worden, K.

2012-09-01

The problem of obtaining the underlying linear dynamic compliance matrix in the presence of nonlinearities in a general multi-degree-of-freedom (MDOF) system can be solved using the conditioned reverse path (CRP) method introduced by Richards and Singh (1998 Journal of Sound and Vibration, 213(4): pp. 673-708). The CRP method also provides a means of identifying the coefficients of any nonlinear terms which can be specified a priori in the candidate equations of motion. Although the CRP has proved extremely useful in the context of nonlinear system identification, it has a number of small issues associated with it. One of these issues is the fact that the nonlinear coefficients are actually returned in the form of spectra which need to be averaged over frequency in order to generate parameter estimates. The parameter spectra are typically polluted by artefacts from the identification of the underlying linear system which manifest themselves at the resonance and anti-resonance frequencies. A further problem is associated with the fact that the parameter estimates are extracted in a recursive fashion which leads to an accumulation of errors. The first minor objective of this paper is to suggest ways to alleviate these problems without major modification to the algorithm. The results are demonstrated on numerically-simulated responses from MDOF systems. In the second part of the paper, a more radical suggestion is made, to replace the conditioned spectral analysis (which is the basis of the CRP method) with an alternative time domain decorrelation method. The suggested approach - the orthogonalised reverse path (ORP) method - is illustrated here using data from simulated single-degree-of-freedom (SDOF) and MDOF systems.

Comparison of Vitek Matrix-assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Versus Conventional Methods in Candida Identification.

Science.gov (United States)

Keçeli, Sema Aşkın; Dündar, Devrim; Tamer, Gülden Sönmez

2016-02-01

Candida species are generally identified by conventional methods such as germ tube or morphological appearance on corn meal agar, biochemical methods using API kits and molecular biological methods. Alternative to these methods, rapid and accurate identification methods of microorganisms called matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDİ-TOF MS) has recently been described. In this study, Candida identification results by API Candida kit, API 20C AUX kit and identifications on corn meal agar (CMA) are compared with the results obtained on Vitek-MS. All results were confirmed by sequencing internal transcribed spacer (ITS) regions of rDNA. Totally, 97 Candida strains were identified by germ tube test, CMA, API and Vitek-MS. Vitek-MS results were compatible with 74.2 % of API 20C AUX and 81.4 % of CMA results. The difference between the results of API Candida and API 20C AUX was detected. The ratio of discrepancy between Vitek-MS and API 20C AUX was 25.8 %. Candida species mostly identified as C. famata or C. tropicalis by and not compatible with API kits were identified as C. albicans by Vitek-MS. Sixteen Candida species having discrepant results with Vitek-MS, API or CMA were randomly chosen, and ITS sequence analysis was performed. The results of sequencing were compatible 56.2 % with API 20C AUX, 50 % with CMA and 93.7 % with Vitek-MS. When compared with conventional identification methods, MS results are more reliable and rapid for Candida identification. MS system may be used as routine identification method in clinical microbiology laboratories.

Building Damage Extraction Triggered by Earthquake Using the Uav Imagery

Science.gov (United States)

Li, S.; Tang, H.

2018-04-01

When extracting building damage information, we can only determine whether the building is collapsed using the post-earthquake satellite images. Even the satellite images have the sub-meter resolution, the identification of slightly damaged buildings is still a challenge. As the complementary data to satellite images, the UAV images have unique advantages, such as stronger flexibility and higher resolution. In this paper, according to the spectral feature of UAV images and the morphological feature of the reconstructed point clouds, the building damage was classified into four levels: basically intact buildings, slightly damaged buildings, partially collapsed buildings and totally collapsed buildings, and give the rules of damage grades. In particular, the slightly damaged buildings are determined using the detected roof-holes. In order to verify the approach, we conduct experimental simulations in the cases of Wenchuan and Ya'an earthquakes. By analyzing the post-earthquake UAV images of the two earthquakes, the building damage was classified into four levels, and the quantitative statistics of the damaged buildings is given in the experiments.

Quantifying traces of tool use: a novel morphometric analysis of damage patterns on percussive tools.

Directory of Open Access Journals (Sweden)

Matthew V Caruana

Full Text Available Percussive technology continues to play an increasingly important role in understanding the evolution of tool use. Comparing the archaeological record with extractive foraging behaviors in nonhuman primates has focused on percussive implements as a key to investigating the origins of lithic technology. Despite this, archaeological approaches towards percussive tools have been obscured by a lack of standardized methodologies. Central to this issue have been the use of qualitative, non-diagnostic techniques to identify percussive tools from archaeological contexts. Here we describe a new morphometric method for distinguishing anthropogenically-generated damage patterns on percussive tools from naturally damaged river cobbles. We employ a geomatic approach through the use of three-dimensional scanning and geographical information systems software to statistically quantify the identification process in percussive technology research. This will strengthen current technological analyses of percussive tools in archaeological frameworks and open new avenues for translating behavioral inferences of early hominins from percussive damage patterns.

Quantifying Traces of Tool Use: A Novel Morphometric Analysis of Damage Patterns on Percussive Tools

Science.gov (United States)

Caruana, Matthew V.; Carvalho, Susana; Braun, David R.; Presnyakova, Darya; Haslam, Michael; Archer, Will; Bobe, Rene; Harris, John W. K.

2014-01-01

Percussive technology continues to play an increasingly important role in understanding the evolution of tool use. Comparing the archaeological record with extractive foraging behaviors in nonhuman primates has focused on percussive implements as a key to investigating the origins of lithic technology. Despite this, archaeological approaches towards percussive tools have been obscured by a lack of standardized methodologies. Central to this issue have been the use of qualitative, non-diagnostic techniques to identify percussive tools from archaeological contexts. Here we describe a new morphometric method for distinguishing anthropogenically-generated damage patterns on percussive tools from naturally damaged river cobbles. We employ a geomatic approach through the use of three-dimensional scanning and geographical information systems software to statistically quantify the identification process in percussive technology research. This will strengthen current technological analyses of percussive tools in archaeological frameworks and open new avenues for translating behavioral inferences of early hominins from percussive damage patterns. PMID:25415303

Rapid method for direct identification of bacteria in urine and blood culture samples by matrix-assisted laser desorption ionization time-of-flight mass spectrometry: intact cell vs. extraction method.

Science.gov (United States)

Ferreira, L; Sánchez-Juanes, F; Muñoz-Bellido, J L; González-Buitrago, J M

2011-07-01

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is a fast and reliable technology for the identification of microorganisms with proteomics approaches. Here, we compare an intact cell method and a protein extraction method before application on the MALDI plate for the direct identification of microorganisms in both urine and blood culture samples from clinical microbiology laboratories. The results show that the intact cell method provides excellent results for urine and is a good initial method for blood cultures. The extraction method complements the intact cell method, improving microorganism identification from blood culture. Thus, we consider that MALDI-TOF MS performed directly on urine and blood culture samples, with the protocols that we propose, is a suitable technique for microorganism identification, as compared with the routine methods used in the clinical microbiology laboratory. © 2010 The Authors. Clinical Microbiology and Infection © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Detection and Identification of Loss of Efficiency Faults of Flight Actuators

Directory of Open Access Journals (Sweden)

Ossmann Daniel

2015-03-01

Full Text Available We propose linear parameter-varying (LPV model-based approaches to the synthesis of robust fault detection and diagnosis (FDD systems for loss of efficiency (LOE faults of flight actuators. The proposed methods are applicable to several types of parametric (or multiplicative LOE faults such as actuator disconnection, surface damage, actuator power loss or stall loads. For the detection of these parametric faults, advanced LPV-model detection techniques are proposed, which implicitly provide fault identification information. Fast detection of intermittent stall loads (seen as nuisances, rather than faults is important in enhancing the performance of various fault detection schemes dealing with large input signals. For this case, a dedicated fast identification algorithm is devised. The developed FDD systems are tested on a nonlinear actuator model which is implemented in a full nonlinear aircraft simulation model. This enables the validation of the FDD system’s detection and identification characteristics under realistic conditions.

New logarithmic technique of diffusivity identification using the flash method; Nouvelle technique logarithmique d`identification de la diffusivite par la methode flash

Energy Technology Data Exchange (ETDEWEB)

Thermitus, M.A.; Laurent, M. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

1997-12-31

Using a logarithmic transformation, the thermogram of a flash experiment can be interpreted as the sum of the adiabatic model solution with a term representative of the losses. Two methods based on this transformation are proposed in this study. They are based on the identification of a parameter that depends on the thickness of the sample and on its diffusivity and not on the experimental conditions. They allow to identify the diffusivity with a high precision even for materials with a low conductivity at high temperatures. (J.S.) 12 refs.

A Simple and Effective Isocratic HPLC Method for Fast Identification and Quantification of Surfactin

International Nuclear Information System (INIS)

Muhammad Qadri Effendy Mubarak; Abdul Rahman Hassan; Aidil Abdul Hamid; Sahaid Khalil; Mohd Hafez Mohd Isa

2015-01-01

The aim of this study was to establish a simple, accurate and reproducible method for the identification and quantification of surfactin using high-performance liquid chromatography (HPLC). Previously reported method of identification and quantification of surfactin were time consuming and requires a large quantity of mobile phase. The new method was achieved by application of Chromolith® high performance RP-18 (100 x 4.6 mm, 5 μm) as the stationary phase and optimization of mobile phase ratio and flow rate. Mobile phase consisted of acetonitrile (ACN) and 3.8 mM trifluroacetic acid (TFA) solution of 80:20 ratio at flow rate of 2.2 mL/ min was obtained as the optimal conditions. Total elution time of the obtained surfactin peaks was four times quicker than various methods previously reported in the literature. The method described here allowed for fine separation of surfactin in standard sample (98 % purity) and surfactin in fermentation broth. (author)

Comparing the ISO-recommended and the cumulative data-reduction algorithms in S-on-1 laser damage test by a reverse approach method

Science.gov (United States)

Zorila, Alexandru; Stratan, Aurel; Nemes, George

2018-01-01

We compare the ISO-recommended (the standard) data-reduction algorithm used to determine the surface laser-induced damage threshold of optical materials by the S-on-1 test with two newly suggested algorithms, both named "cumulative" algorithms/methods, a regular one and a limit-case one, intended to perform in some respects better than the standard one. To avoid additional errors due to real experiments, a simulated test is performed, named the reverse approach. This approach simulates the real damage experiments, by generating artificial test-data of damaged and non-damaged sites, based on an assumed, known damage threshold fluence of the target and on a given probability distribution function to induce the damage. In this work, a database of 12 sets of test-data containing both damaged and non-damaged sites was generated by using four different reverse techniques and by assuming three specific damage probability distribution functions. The same value for the threshold fluence was assumed, and a Gaussian fluence distribution on each irradiated site was considered, as usual for the S-on-1 test. Each of the test-data was independently processed by the standard and by the two cumulative data-reduction algorithms, the resulting fitted probability distributions were compared with the initially assumed probability distribution functions, and the quantities used to compare these algorithms were determined. These quantities characterize the accuracy and the precision in determining the damage threshold and the goodness of fit of the damage probability curves. The results indicate that the accuracy in determining the absolute damage threshold is best for the ISO-recommended method, the precision is best for the limit-case of the cumulative method, and the goodness of fit estimator (adjusted R-squared) is almost the same for all three algorithms.

Simple estimating method of damages of concrete gravity dam based on linear dynamic analysis

Energy Technology Data Exchange (ETDEWEB)

Sasaki, T.; Kanenawa, K.; Yamaguchi, Y. [Public Works Research Institute, Tsukuba, Ibaraki (Japan). Hydraulic Engineering Research Group

2004-07-01

Due to the occurrence of large earthquakes like the Kobe Earthquake in 1995, there is a strong need to verify seismic resistance of dams against much larger earthquake motions than those considered in the present design standard in Japan. Problems exist in using nonlinear analysis to evaluate the safety of dams including: that the influence which the set material properties have on the results of nonlinear analysis is large, and that the results of nonlinear analysis differ greatly according to the damage estimation models or analysis programs. This paper reports the evaluation indices based on a linear dynamic analysis method and the characteristics of the progress of cracks in concrete gravity dams with different shapes using a nonlinear dynamic analysis method. The study concludes that if simple linear dynamic analysis is appropriately conducted to estimate tensile stress at potential locations of initiating cracks, the damage due to cracks would be predicted roughly. 4 refs., 1 tab., 13 figs.

Comparing Methods of Calculating Expected Annual Damage in Urban Pluvial Flood Risk Assessments

Directory of Open Access Journals (Sweden)

Anders Skovgård Olsen

2015-01-01

Full Text Available Estimating the expected annual damage (EAD due to flooding in an urban area is of great interest for urban water managers and other stakeholders. It is a strong indicator for a given area showing how vulnerable it is to flood risk and how much can be gained by implementing e.g., climate change adaptation measures. This study identifies and compares three different methods for estimating the EAD based on unit costs of flooding of urban assets. One of these methods was used in previous studies and calculates the EAD based on a few extreme events by assuming a log-linear relationship between cost of an event and the corresponding return period. This method is compared to methods that are either more complicated or require more calculations. The choice of method by which the EAD is calculated appears to be of minor importance. At all three case study areas it seems more important that there is a shift in the damage costs as a function of the return period. The shift occurs approximately at the 10 year return period and can perhaps be related to the design criteria for sewer systems. Further, it was tested if the EAD estimation could be simplified by assuming a single unit cost per flooded area. The results indicate that within each catchment this may be a feasible approach. However the unit costs varies substantially between different case study areas. Hence it is not feasible to develop unit costs that can be used to calculate EAD, most likely because the urban landscape is too heterogeneous.

Radiation damage and its repair in non-sporulating bacteria

International Nuclear Information System (INIS)

Moseley, B.E.B.

1984-01-01

A review is given of radiation damage and its repair in non-sporulating bacteria. The identification and measurement of radiation damage in the DNA of the bacteria after exposure to ultraviolet radiation and ionizing radiation is described. Measuring the extent of DNA repair and ways of isolating repair mutants are also described. The DNA repair mechanisms for UV-induced damage are discussed including photoreactivation repair, excision repair, post-replication recombination repair and induced error-prone repair. The DNA repair mechanisms for ionizing radiation damage are also discussed including the repair of both single and double-strand breaks. Other aspects discussed include the effects of growth, irradiation medium and recovery medium on survival, DNA repair in humans, the commercial use of UV and ionizing radiations and the future of ionizing irradiation as a food treatment process. (U.K.)

OPTICAL correlation identification technology applied in underwater laser imaging target identification

Science.gov (United States)

Yao, Guang-tao; Zhang, Xiao-hui; Ge, Wei-long

2012-01-01

The underwater laser imaging detection is an effective method of detecting short distance target underwater as an important complement of sonar detection. With the development of underwater laser imaging technology and underwater vehicle technology, the underwater automatic target identification has gotten more and more attention, and is a research difficulty in the area of underwater optical imaging information processing. Today, underwater automatic target identification based on optical imaging is usually realized with the method of digital circuit software programming. The algorithm realization and control of this method is very flexible. However, the optical imaging information is 2D image even 3D image, the amount of imaging processing information is abundant, so the electronic hardware with pure digital algorithm will need long identification time and is hard to meet the demands of real-time identification. If adopt computer parallel processing, the identification speed can be improved, but it will increase complexity, size and power consumption. This paper attempts to apply optical correlation identification technology to realize underwater automatic target identification. The optics correlation identification technology utilizes the Fourier transform characteristic of Fourier lens which can accomplish Fourier transform of image information in the level of nanosecond, and optical space interconnection calculation has the features of parallel, high speed, large capacity and high resolution, combines the flexibility of calculation and control of digital circuit method to realize optoelectronic hybrid identification mode. We reduce theoretical formulation of correlation identification and analyze the principle of optical correlation identification, and write MATLAB simulation program. We adopt single frame image obtained in underwater range gating laser imaging to identify, and through identifying and locating the different positions of target, we can improve

Size-related variation in arm damage frequency in the crown-of-thorns sea star, Acanthaster planci

Directory of Open Access Journals (Sweden)

Jairo Rivera-Posada

2014-03-01

Full Text Available Objective: To examine variation in the frequency of arm damage in different sizes of Acanthaster planci (A. planci, assess how this damage is inflicted by fish predators, and infer the potential role of predation in population regulation. Methods: Diameters of A. planci collected from three sites in the Philippines were measured and arm damage frequency and severity was assessed. Frequency of arm damage was compared between sizes. Feeding behavior of fish predators was also observed in the laboratory. Results: This study demonstrates that sublethal predation by triggerfishes on A. planci result in extensive arm damage. Overall, 60% of A. planci sampled across all sites had sublethal injuries. The frequency of individuals with missing or regenerating arms was highest in medium-sized young adults (11-20 cm, which coincides with the phase where A. planci shift from cryptic to exposed daytime feeding. Conclusions: The high incidence of arm damage within intermediate-sized sea stars indicates that predators exercise some level of regulation on A. planci populations at a local scale. Identification and protection of putative predators that target the most vulnerable life history stages of A. planci are essential in developing population control strategies and reverse sustained declines in coral cover.

Comparison among three methods for mycobacteria identification Comparación entre tres métodos para identificar micobacterias

OpenAIRE

Misael Mondragón-Barreto; Carlos A. Vázquez-Chacón; Candelaria Barrón-Rivero; Patricia Acosta-Blanco; Kenneth C. Jost Jr; Susana Balandrano; Hiram Olivera-Díaz

2000-01-01

OBJECTIVE: To compare three methods: Biochemical tests, high-performance liquid chromatography (HPLC) and polymerase chain reaction-restriction fragments length polymorphism (PCR-RFLP), for the identification of mycobacteria, and to perform a cost-benefit analysis to define an optimum identification algorithm. MATERIAL AND METHODS: One-hundred-and-seven mycobacteria isolates were identified by the three methods at Instituto de Diagnóstico y Referencia Epidemiológicos, between February of 1999...

Bayesian inference method for stochastic damage accumulation modeling

International Nuclear Information System (INIS)

Jiang, Xiaomo; Yuan, Yong; Liu, Xian

2013-01-01

Damage accumulation based reliability model plays an increasingly important role in successful realization of condition based maintenance for complicated engineering systems. This paper developed a Bayesian framework to establish stochastic damage accumulation model from historical inspection data, considering data uncertainty. Proportional hazards modeling technique is developed to model the nonlinear effect of multiple influencing factors on system reliability. Different from other hazard modeling techniques such as normal linear regression model, the approach does not require any distribution assumption for the hazard model, and can be applied for a wide variety of distribution models. A Bayesian network is created to represent the nonlinear proportional hazards models and to estimate model parameters by Bayesian inference with Markov Chain Monte Carlo simulation. Both qualitative and quantitative approaches are developed to assess the validity of the established damage accumulation model. Anderson–Darling goodness-of-fit test is employed to perform the normality test, and Box–Cox transformation approach is utilized to convert the non-normality data into normal distribution for hypothesis testing in quantitative model validation. The methodology is illustrated with the seepage data collected from real-world subway tunnels.

Evaluation of Different Methods for Identification of Structural Alerts Using Chemical Ames Mutagenicity Data Set as a Benchmark.

Science.gov (United States)

Yang, Hongbin; Li, Jie; Wu, Zengrui; Li, Weihua; Liu, Guixia; Tang, Yun

2017-06-19

Identification of structural alerts for toxicity is useful in drug discovery and other fields such as environmental protection. With structural alerts, researchers can quickly identify potential toxic compounds and learn how to modify them. Hence, it is important to determine structural alerts from a large number of compounds quickly and accurately. There are already many methods reported for identification of structural alerts. However, how to evaluate those methods is a problem. In this paper, we tried to evaluate four of the methods for monosubstructure identification with three indices including accuracy rate, coverage rate, and information gain to compare their advantages and disadvantages. The Kazius' Ames mutagenicity data set was used as the benchmark, and the four methods were MoSS (graph-based), SARpy (fragment-based), and two fingerprint-based methods including Bioalerts and the fingerprint (FP) method we previously used. The results showed that Bioalerts and FP could detect key substructures with high accuracy and coverage rates because they allowed unclosed rings and wildcard atom or bond types. However, they also resulted in redundancy so that their predictive performance was not as good as that of SARpy. SARpy was competitive in predictive performance in both training set and external validation set. These results might be helpful for users to select appropriate methods and further development of methods for identification of structural alerts.