scholarly journals Sensitivity Analysis of a CPAM Inverse Algorithm for Composite Laminates Characterization

2017 ◽  
Vol 2017 ◽  
pp. 1-14
Author(s):  
Farshid Masoumi ◽  
Ahmad Ghasemi Ghalebahman
Keyword(s):  
Sensitivity Analysis ◽  
Composite Laminates ◽  
Numerical Solutions ◽  
Error Function ◽  
Simulated Data ◽  
Optimization Procedure ◽  
Unknown Parameters ◽  
Finite Element Package

Using experimental data and numerical simulations, a new combined technique is presented for characterization of thin and thick orthotropic composite laminates. Four or five elastic constants, as well as ply orientation angles, are considered as the unknown parameters. The material characterization is first examined for isotropic plates under different boundary conditions to evaluate the method’s accuracy. The proposed algorithm, so-called CPAM (Combined Programs of ABAQUS and MATLAB), utilizes an optimization procedure and makes simultaneous use of vibration test data together with their corresponding numerical solutions. The numerical solutions are based on a commercial finite element package for efficiently identifying the material properties. An inverse method based on particle swarm optimization algorithm is further provided using MATLAB software. The error function to be minimized is the sum of squared differences between experimental and simulated data of eigenfrequencies. To evaluate the robustness of the model’s results in the presence of uncertainty and unwanted noises, a sensitivity analysis that employs Gaussian disorder model is directly applied to the measured frequencies. The results with high accuracy confirm the validity and capability of the present method in simultaneous determination of mechanical constants and fiber orientation angles of composite laminates as compared to prior methods.

Critical assessment of bioinformatics methods for the characterization of pathological repeat expansions with single-molecule sequencing data

2019 ◽  
Vol 21 (6) ◽  
pp. 1971-1986 ◽  
Author(s):  
Matteo Chiara ◽  
Federico Zambelli ◽  
Ernesto Picardi ◽  
David S Horner ◽  
Graziano Pesole
Keyword(s):  
Single Molecule ◽  
Tandem Repeats ◽  
Simulated Data ◽  
Detailed Comparison ◽  
Sequencing Data ◽  
Single Molecule Sequencing ◽  
Sequencing Technologies ◽  
Repeat Expansions

Abstract A number of studies have reported the successful application of single-molecule sequencing technologies to the determination of the size and sequence of pathological expanded microsatellite repeats over the last 5 years. However, different custom bioinformatics pipelines were employed in each study, preventing meaningful comparisons and somewhat limiting the reproducibility of the results. In this review, we provide a brief summary of state-of-the-art methods for the characterization of expanded repeats alleles, along with a detailed comparison of bioinformatics tools for the determination of repeat length and sequence, using both real and simulated data. Our reanalysis of publicly available human genome sequencing data suggests a modest, but statistically significant, increase of the error rate of single-molecule sequencing technologies at genomic regions containing short tandem repeats. However, we observe that all the methods herein tested, irrespective of the strategy used for the analysis of the data (either based on the alignment or assembly of the reads), show high levels of sensitivity in both the detection of expanded tandem repeats and the estimation of the expansion size, suggesting that approaches based on single-molecule sequencing technologies are highly effective for the detection and quantification of tandem repeat expansions and contractions.

Parameter Identification for Multibody Dynamic Systems

1997 ◽  
Author(s):  
Radu Serban ◽  
Jeffrey S. Freeman ◽  
Dan Negrut
Keyword(s):  
Sensitivity Analysis ◽  
Parameter Identification ◽  
Dynamic Systems ◽  
Time History ◽  
Optimization Procedure ◽  
Optimal Choice ◽  
Least Square ◽  
Unknown Parameters ◽  
Multibody Dynamic ◽  
Dynamic Sensitivity Analysis

Abstract This paper presents a parameter identification technique for multibody dynamic systems, based on a nonlinear least-square optimization procedure. The procedure identifies unknown parameters in the differential-algebraic multibody system model by matching the acceleration time history of a point of interest with given data. Derivative information for the optimization process is obtained through dynamic sensitivity analysis. Direct differentiation methods are used to perform the sensitivity analysis. Examples of the procedure are presented, applying the technique both to perfect data; i.e. data produced by the assumed model with the optimal choice of parameters, and to experimental data; i.e. data measured on the real system and thus subject to noise and modelling imperfections.

Identification of mechanical and damage parameters of composite laminates based on a CPAM method

2018 ◽  
Vol 37 (17) ◽  
pp. 1114-1128 ◽  
Author(s):  
Farshid Masoumi ◽  
Ahmad Ghasemi-Ghalebahman ◽  
Mohammad-Javad Kokabi
Keyword(s):  
Mechanical Properties ◽  
Numerical Solution ◽  
Composite Laminates ◽  
Natural Frequencies ◽  
Error Function ◽  
Numerical Data ◽  
Optimization Procedure ◽  
Composite Plates ◽  
Mode Shapes ◽  
Layer Width

A new method combining experimental and numerical data is proposed to simultaneously determine the mechanical properties and damage parameters in multilayered composite plates. Studied parameters are mechanical properties of each layer, width and length of delamination zone, location of damage’s center, and interface location of the damage. In this method, the PSO optimization procedure based on a CPAM algorithm uses vibration test data along with their corresponding numerical solution. Vibration data are the plates’ natural frequencies and mode shapes obtained in the modal laboratory. In order to efficiently investigate the studied parameters, the numerical solution is investigated by a commercial finite element package. The error function constitutes two parts, one part is included by the sum of the squared differences between experimental and numerical natural frequencies and the other is based on the mode shapes data. The mode shapes’ curvatures are also utilized to achieve high sensitivity to small faults. Moreover, by applying a Gaussian disorder model to the vibrational data, the sensitivity of the method is evaluated in the presence of unwanted noises. The results confirm the robustness of the proposed study for identifying both mechanical constants and damage parameters in composite plates.

scholarly journals QUANTUM ESTIMATION FOR QUANTUM TECHNOLOGY

2009 ◽  
Vol 07 (supp01) ◽  
pp. 125-137 ◽  
Author(s):  
MATTEO G. A. PARIS
Keyword(s):  
Quantum Noise ◽  
Signal To Noise Ratio ◽  
Logarithmic Derivative ◽  
Quantum Fisher Information ◽  
Optimization Procedure ◽  
Nonlinear Functions ◽  
Quantum Observables ◽  
Quantum Technology

Several quantities of interest in quantum information, including entanglement and purity, are nonlinear functions of the density matrix and cannot, even in principle, correspond to proper quantum observables. Any method aimed to determine the value of these quantities should resort to indirect measurements and thus corresponds to a parameter estimation problem whose solution, i.e. the determination of the most precise estimator, unavoidably involves an optimization procedure. We review local quantum estimation theory and present explicit formulas for the symmetric logarithmic derivative and the quantum Fisher information of relevant families of quantum states. Estimability of a parameter is defined in terms of the quantum signal-to-noise ratio and the number of measurements needed to achieve a given relative error. The connections between the optmization procedure and the geometry of quantum statistical models are discussed. Our analysis allows to quantify quantum noise in the measurements of non observable quantities and provides a tools for the characterization of signals and devices in quantum technology.

DETERMINATION OF PROPERTIES OF THIN FILMS USING X-RAY REFLECTIVITY

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1072-1079 ◽  
Author(s):  
K. CHEW ◽  
S. F. YOON ◽  
H. K. CHAN ◽  
C. F. NG ◽  
Q. ZHANG ◽  
...  
Keyword(s):  
Direct Determination ◽  
Interface Layer ◽  
Unknown Parameters ◽  
Film Properties ◽  
X Ray ◽  
Main Layer ◽  
Reflectivity Spectra ◽  
Non Destructive

X-ray reflectivity (XRR) is a sensitive and non-destructive technique for the characterization of surfaces and thin film properties. Due to the spectroscopic nature of the problem, the unknown parameters are solved indirectly by fitting the theoretical reflectivity spectra to the experimental spectra. In this work, we propose three algorithms that allow the direct determination of the properties, which are more efficient compared to the fitting process that requires initial guesses, and whose convergence depends critically on the goodness of the guesses. The algorithms are developed for a structure with a one-layer film on a substrate. However, for films having an additional top surface layer, or an interface layer next to the substrate, the algorithms can also be applied to approximately deduce the parameters of the main layer of film.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

SEM/EDS Characterization of Uncommon Metal Whiskers and Determination of Underlying Growth Mechanisms

2018 ◽  
Author(s):  
D. Basak ◽  
L. H. Ponce
Keyword(s):  
Reliability Analysis ◽  
Case Studies ◽  
Whisker Growth ◽  
Innovation Systems ◽  
Growth Mechanisms ◽  
Crystal Oscillator ◽  
Analysis Laboratory ◽  
Investigative Techniques

Abstract Two case-studies on uncommon metals whiskers, performed at the Reliability Analysis Laboratory (RAL) of Northrop Grumman Innovation Systems, are presented. The components analyzed are an Oven Controlled Crystal Oscillator (OCXO) and an Electromechanical Relay. Investigative techniques were used to determine the chemical and physical makeup of the metal whiskers and develop an understanding of the underlying effects and mechanisms that caused the conditions conducive to whisker growth.

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