scholarly journals Estimation of Acoustic Source Positioning Error Determined by One-Dimensional Linear Location Technique

2021 ◽  
Vol 12 (1) ◽  
pp. 224
Author(s):  
Artem Marchenkov ◽  
Igor Vasiliev ◽  
Dmitriy Chernov ◽  
Daria Zhgut ◽  
Daria Moskovskaya ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Element Model ◽  
Positioning Error ◽  
Acoustic Source ◽  
New Approach ◽  
One Dimensional ◽  
Flat Steel ◽  
The One ◽  
Source Positioning ◽  
Ae Signals

The one-dimensional (1D) linear location technique has been considered as one of the methods for determining the position of acoustic emission (AE) sources in metallic objects. However, this approach does not take into account the heterogeneity of materials and that leads to poor accuracy of AE sources localization. To estimate the positioning error of the linear location technique which is typically used to determine the AE source location a new approach based on the combination of experimental and simulation methods is proposed. This approach for error estimation contains a finite element model construction of the AE signals localization. The model consists of transmitting and receiving transducers mounted on the test object, the frequency response of which selected close to the characteristics of acoustic emission transducers applied in the preliminary experiments. The application of the approach in current research showed that a reduced positioning error on a flat steel plate reaches 15%. The proposed technique can be used to optimize the number of preliminary tests required to calculate the reduced error of the 1D linear location technique applied for the AE sources localization during the inspection of the structure.

Analysis of 1D Abrasive Vibratory Finishing Using Acoustic Emission

2013 ◽  
Author(s):  
Pradeep Kumar Prakasam ◽  
Sathyan Subbiah
Keyword(s):  
Acoustic Emission ◽  
Monitoring And Control ◽  
Machining Processes ◽  
Vibratory Finishing ◽  
One Dimensional ◽  
Oblique Impacts ◽  
The Media ◽  
The One ◽  
And Control ◽  
Ae Signals

Acoustic emission (AE) is a widely used non-destructive method for monitoring and control of machining processes. Vibratory finishing is a surface modification process used for polishing, deburring and finishing of components (aerospace, automotive and other industries). The polishing action takes place due to the action of abrasive particles called media on the components subjected to finishing. The media motion is complex and involves a combination of normal and oblique impacts, scratching and rolling. This work deals with the characterization of basic types of media contact occurring in the vibratory finishing process using acoustic emission signals. A novel one dimensional vibratory simulator was developed for this purpose using a tribometer setup. The one dimensional simulator was used to differentiate between the normal and scratching types of media contact and corresponding AE signals were measured. The preliminary results shows that the AE signals obtained for normal and scratching type of contacts are different. In addition to this, AE signals were used to characterize the amount of media.

scholarly journals On a direct method for the determination of an exact invariant for the time-dependent harmonic oscillator

1977 ◽  
Vol 20 (1) ◽  
pp. 97-105 ◽  
Author(s):  
P. G. L. Leach
Keyword(s):  
Direct Method ◽  
Dynamical Symmetry ◽  
Time Dependent ◽  
Symmetry Groups ◽  
New Approach ◽  
One Dimensional ◽  
The One ◽  
A Direct Method ◽  
Exact Invariant

AbstractAn exact invariant is found for the one-dimensional oscillator with equation of motion . The method used is that of linear canonical transformations with time-dependent coeffcients. This is a new approach to the problem and has the advantage of simplicity. When f(t) and g(t) are zero, the invariant is related to the well-known Lewis invariant. The significance of extension to higher dimension of these results is indicated, in particular for the existence of non-invariance dynamical symmetry groups.

Analysis of Thin-Walled Closed Beams With General Quadrilateral Cross Sections

1999 ◽  
Vol 66 (4) ◽  
pp. 904-912 ◽  
Author(s):  
J. H. Kim ◽  
Y. Y. Kim
Keyword(s):  
Finite Element ◽  
Cross Sections ◽  
Distortion Function ◽  
Element Formulation ◽  
Numerical Work ◽  
New Approach ◽  
One Dimensional ◽  
Static And Dynamic Analysis ◽  
Thin Walled ◽  
The One

This paper deals with the one-dimensional static and dynamic analysis of thin-walled closed beams with general quadrilateral cross sections. The coupled deformations of distortion as well as torsion and warping are investigated in this work. A new approach to determine the functions describing section deformations is proposed. In particular, the present distortion function satisfies all the necessary continuity conditions unlike Vlasov's distortion function. Based on these section deformation functions, a one-dimensional theory dealing with the coupled deformations is presented. The actual numerical work is carried out using two-node C0 finite element formulation. The present one-dimensional results for some static and free-vibration problems are compared with the existing and the plate finite element results.

A New Approach to The Design of Fan Volute Profiles

1996 ◽  
Vol 210 (3) ◽  
pp. 287-294 ◽  
Author(s):  
D T Qi ◽  
M J Pomfret ◽  
K Lam
Keyword(s):  
Design Method ◽  
Operating Conditions ◽  
Flow Angle ◽  
New Approach ◽  
One Dimensional ◽  
Distribution Form ◽  
Flow Parameters ◽  
Centrifugal Fans ◽  
Ultimate Objective ◽  
The One

In traditional volute design methods, the flow at the volute inlet is assumed to be uniform according to one-dimensional theory. However, many experimental results have shown that under the design operating conditions, the actual distributions of the flow parameters at the volute inlet are different from those predicted by the ideal assumption. This is because of the influence of the non-axisymmetrical volute geometry, especially due to the presence of the volute tongue. Based on this fact, a new method was considered whereby different volute profiles can be generated by varying the distributions of flow parameters at the volute inlet. The ultimate objective is to achieve the optimal volute profile design so that the performance of a centrifugal machine can be improved. In this paper, a two-dimensional inverse method has been used to redesign the original volute profiles of two centrifugal fans. The results show that the method presented provides effective improvement to the one-dimensional volute design method. The controlled distribution form of volute inlet flow angle α4 in the redesign is qualitatively discussed and can be used for reference in the volute design and further research.

scholarly journals A New Approach for Error Reduction in the Volume Penalization Method

2014 ◽  
Vol 16 (5) ◽  
pp. 1181-1200 ◽  
Author(s):  
Wakana Iwakami ◽  
Yuzuru Yatagai ◽  
Nozomu Hatakeyama ◽  
Yuji Hattori
Keyword(s):  
Diffusion Equation ◽  
Stokes Equations ◽  
Error Reduction ◽  
Penalization Method ◽  
New Approach ◽  
One Dimensional ◽  
Dimensional Diffusion ◽  
Mask Function ◽  
The One ◽  
Volume Penalization Method

AbstractA new approach for reducing error of the volume penalization method is proposed. The mask function is modified by shifting the interface between solid and fluid by toward the fluid region, where v and η are the viscosity and the permeability, respectively. The shift length is derived from the analytical solution of the one-dimensional diffusion equation with a penalization term. The effect of the error reduction is verified numerically for the one-dimensional diffusion equation, Burgers’ equation, and the two-dimensional Navier-Stokes equations. The results show that the numerical error is reduced except in the vicinity of the interface showing overall second-order accuracy, while it converges to a non-zero constant value as the number of grid points increases for the original mask function. However, the new approach is effectivewhen the grid resolution is sufficiently high so that the boundary layer,whose width is proportional to , is resolved. Hence, the approach should be used when an appropriate combination of ν and η is chosen with a given numerical grid.

A Finite-Element Simulation of Pulsatile Flow in Flexible Obstructed Tubes

1982 ◽  
Vol 104 (2) ◽  
pp. 119-124 ◽  
Author(s):  
E. Rooz ◽  
D. F. Young ◽  
T. R. Rogge
Keyword(s):  
Finite Element ◽  
Pulsatile Flow ◽  
Continuity Equation ◽  
Element Model ◽  
Momentum Equation ◽  
Cross Sectional ◽  
One Dimensional ◽  
Element Simulation ◽  
The One

A finite-element model for pulsatile flow in a straight flexible partially obstructed tube is developed. In the unobstructed sections of the tube the model considers the continuity equation, the one-dimensional momentum equation, and an equation of state relating tube cross-sectional area to pressure. For the obstructed region, a nonlinear relationship between the flow and the pressure drop across the stenosis is considered. The applicability of a model is checked by comparing predicted flow and pressure waveforms with corresponding in-vitro experimental measurements obtained on a mechanical system. These comparisons indicate that the model satisfactorily predicts pressures and flows under variety of frequencies of oscillation and stenosis severities.

Mathematical models of arterial transmural transport

1985 ◽  
Vol 248 (2) ◽  
pp. H240-H263 ◽  
Author(s):  
D. L. Fry
Keyword(s):  
Driving Forces ◽  
Water Flux ◽  
Element Model ◽  
Parameter Estimates ◽  
Convective Velocity ◽  
Reversible Binding ◽  
One Dimensional ◽  
Coefficients Of Variation ◽  
The One ◽  
Molecular Sieving

A finite-element model (FEM) and corresponding five-parameter analytical model (AM) were derived to study the one-dimensional transport of chemically reactive macro-molecules across (x) arterial tissue. Derivations emphasize chemical activity [a(x)], its gradient, and water flux as driving forces for chemical reactions and transport. The AM was fitted to 28 measured 125I-albumin transmural concentration [c(x)] curves giving parameter estimates of diffusivity (DA), convective velocity (nu A), and so on as functions of pressure (P), location (z) along the vessel, etc. The FEM was used to study 1) intimal-medial a(x) associated with molecular sieving and medial edema, 2) reversible binding, and 3) errors of AM in analysis of c(x). Results are as follows. Average relative error for the 28 AM fits was 5.3%. Only estimates of DA and nu A had acceptable coefficients of variation. DA (approximately 0.10 X 10(-7) cm2 X s-1) decreased with P, increased with z to a maximum, and then decreased; nu A was approximately proportional to P (approximately 0.12 X 10(-7) cm X s-1 X mmHg-1) and decreased slightly with z; distribution coefficient (epsilon F) decreased with z and was smaller for serum than for simple albumin reagent. Assumed boundary conditions for AM were associated with approximately 1.4% error in AM c(x). Parameter estimates were sensitive to wall inhomogeneity, e.g., approximately 15% error. In conclusion, the AM and FEM simulated measured c(x) well; the FEM is useful for study of mechanisms, experimental designs, and AM errors; trends of AM parameter estimates suggest dependence on P, z, and composition of reagent for further FEM and experimental study.

Application of Genetic Algorithm to Minimize the Number of Objects Processed and Setup in a One-Dimensional Cutting Stock Problem

2013 ◽  
pp. 32-45
Author(s):  
Julliany Sales Brandão ◽  
Alessandra Martins Coelho ◽  
João Flávio V. Vasconcellos ◽  
Luiz Leduíno de Salles Neto ◽  
André Vieira Pinto
Keyword(s):  
Genetic Algorithm ◽  
Objective Function ◽  
Model Problem ◽  
Cutting Stock Problem ◽  
Cutting Stock ◽  
Computational Results ◽  
New Approach ◽  
One Dimensional ◽  
The One

This paper presents the application of the one new approach using Genetic Algorithm in solving One-Dimensional Cutting Stock Problems in order to minimize two objectives, usually conflicting, i.e., the number of processed objects and setup while simultaneously treating them as a single goal. The model problem, the objective function, the method denominated SingleGA10 and the steps used to solve the problem are also presented. The obtained results of the SingleGA10 are compared to the following methods: SHP, Kombi234, ANLCP300 and Symbio10, found in literature, verifying its capacity to find feasible and competitive solutions. The computational results show that the proposed method, which only uses a genetic algorithm to solve these two objectives inversely related, provides good results.

The New Approach to the Invariant Feature Extraction Using Ridgelet Transform

2014 ◽  
Vol 651-653 ◽  
pp. 2241-2244
Author(s):  
Ying Yu ◽  
Cai Lin Dong ◽  
Bo Wen Sheng ◽  
Wei Dan Zhong ◽  
Xiang Lin Zou
Keyword(s):  
Feature Extraction ◽  
Fourier Transform ◽  
Feature Vector ◽  
Typical Feature ◽  
Chinese Characters ◽  
New Approach ◽  
Ridgelet Transform ◽  
One Dimensional ◽  
Invariant Feature ◽  
The One

With the aim to meet the requirements of multi-directional choice, the paper raise a new approach to the invariant feature extraction of handwritten Chinese characters, with ridgelet transform as its foundation. First of all, the original images will be rotated to the Radon circular shift by means of Radon transform. On the basis of the characteristic that Fourier transform is row shift invariant, then, the one-dimensional Fourier transform will be adopted in the Radon domain to gain the conclusion that magnitude matrixes bear the rotation-invariance as a typical feature, which is pretty beneficial to the invariant feature extraction of rotation. When such is done, one-dimensional wavelet transform will be carried out in the direction of rows, thus achieving perfect choice of frequency, which makes it possible to extract the features of sub-line in the appropriate frequencies. Finally, the average values, standard deviations and the energy values will form the feature vector which is extracted from the ridgelet sub-bands. The approaches mentioned in the paper could satisfy the requirements from the form automatic processing on the recognition of handwritten Chinese characters.

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