Reduction of Forced Vibration Response by Optimum Balance of Linkage and Optimum Design of System

1997 ◽  
Author(s):  
She-min Zhang ◽  
Nobuyoshi Morita ◽  
Takao Torii
Keyword(s):  
Objective Function ◽  
Root Mean Square ◽  
Forced Vibration ◽  
Vibration Response ◽  
New Method ◽  
Mean Square ◽  
Design Variables ◽  
Calculation Results ◽  
Angular Velocities ◽  
Optimum Balance

Abstract This paper proposes a new method to reduce the forced vibration response of frame of linkage. It is that the root-mean-square (RMS) value of binary maximum (Bmax) of forced vibration response at a series of angular velocities is taken as the objective function, and the counterweight mass parameters of links and the stiffness factors are used as design variables. Then, it is found out that the responses are related not only to the Bmax value of shaking forces, but also to the shape of curve of shaking forces. The calculation results are compared with those of two other methods used in the reduction of forced vibration response by optimized balance of linkages, and it is shown that the new method can significantly reduce the responses of frame of linkage.

Achieving Heat Flux Uniformity Using an Optimal Arrangement of Impinging Jet Arrays

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
M. Forouzanmehr ◽  
H. Shariatmadar ◽  
F. Kowsary ◽  
M. Ashjaee
Keyword(s):  
Heat Flux ◽  
Nusselt Number ◽  
Objective Function ◽  
Uniform Distribution ◽  
Root Mean Square ◽  
Local Nusselt Number ◽  
Target Surface ◽  
Mean Square ◽  
Optimal Arrangement ◽  
Design Variables

In order to achieve uniform distribution of heat flux over an isothermal heated target surface, a numerical algorithm is developed to obtain an optimized array of four laminar impinging slot jets. Root mean square deviation of the local Nusselt distribution from the desired Nusselt number is considered as the objective function. Jets' widths, jet-to-jet and jet-to-surface spacings, and the overall flow rate are chosen as design variables. Conjugate gradients method along with backtracking line search is applied to optimize the objective function calculated by numerical simulation for three different cases of Nu = 7, 9, and 11. For each of these desired Nusselt numbers, an almost uniform distribution of local Nusselt number with percent of root mean square error less than 2.5% is achieved in fewer than 12 iterations. An experimental study using a Mach–Zehnder interferometer (MZI) has been performed. The measured distribution of local Nusselt number is in good agreement with numerical results in all three optimal configurations.

scholarly journals Normalised Root Mean Square and Amplitude of Sidebands of Vibration Response as Tools for Gearbox Diagnosis

Strain ◽  
2012 ◽  
Vol 48 (6) ◽  
pp. 445-452 ◽  
Author(s):  
P. J. Rzeszucinski ◽  
J. K. Sinha ◽  
R. Edwards ◽  
A. Starr ◽  
B. Allen
Keyword(s):  
Root Mean Square ◽  
Vibration Response ◽  
Mean Square

New method for rapid determination of crystal orientation via Kikuchi patterns

1995 ◽  
Vol 10 (12) ◽  
pp. 3026-3036
Author(s):  
G.P.E.M. Van Bakel ◽  
D.N. Seidman
Keyword(s):  
Electron Microscopy ◽  
Root Mean Square ◽  
Measurement Errors ◽  
Rapid Determination ◽  
New Method ◽  
Complete Analysis ◽  
Mean Square ◽  
Crystal Orientations ◽  
Diffraction Patterns ◽  
Projection Center

Kikuchi electron diffraction patterns are used extensively to determine crystal orientations via transmission electron microscopy (TEM) or in the electron backscattering pattern (EBSP) mode of scanning electron microscopy (SEM). A new method is presented that is capable of finding crystal orientations, the camera length, and the projection center from only one pattern per grain using a least-squares technique. This method eliminates the need to perform an alignment with a reference crystal in the backscattering mode. Application to a Σ = 13a silicon bicrystal is presented for TEM patterns and EBSP's. A complete analysis of the propagation of random measurement errors into the disorientation axis/angle pair is carried out. The root mean square deviation from the nominal disorientation angle is found to be 0.3°in the case of TEM and 0.5°in the case of EBSP. The root mean square inclination between the nominal and measured disorientation axis is found to be 1°in the case of TEM and 0.5°in the case of EBSP.

Crack identification in a cross-stiffened plate system using the root mean square of time domain responses

2006 ◽  
Vol 33 (8) ◽  
pp. 989-1004 ◽  
Author(s):  
A Budipriyanto ◽  
M R Haddara ◽  
A S.J Swamidas
Keyword(s):  
Root Mean Square ◽  
Vibration Response ◽  
Physical Models ◽  
Scale Model ◽  
Resonance Excitation ◽  
Easy Access ◽  
Crack Identification ◽  
Mean Square ◽  
Crack Location ◽  
Side Shell

On-line identification of cracks occurring in large structures has attracted the attention of many researchers. Identification becomes difficult when there is no easy access available for investigators to employ conventional nondestructive evaluation techniques. In this paper, a scheme is presented for identifying the crack location and its extent using vibration response. Numerical studies were carried out on a 1/20th-scale model of the side shell of the structure of a ship. The first natural frequency of the numerical model was 584.3 Hz. The numerical and physical models were excited by a random force having a dominant spectral frequency of 2 Hz. Cracks under investigation occurred at the connection between a horizontal and bulkheads and at the intersection between horizontals and a web frame. A scheme using the root mean square of vibration response is presented for identifying cracks occurring in the flange and web of the horizontal. It is demonstrated that the scheme can identify the crack location and size.Key words: side shell of a ship model, pre-resonance excitation regime, vibration-based monitoring.

scholarly journals ANALISIS KALIBRASI MODEL HSS CLARK DENGAN MENGGUNAKAN PROGRAM HEC-HMS

2018 ◽  
Vol 6 (2) ◽  
pp. 15-22
Author(s):  
Syahrul Ramadhani ◽  
Yohanna Lilis Handayani ◽  
Sigit Sutikno
Keyword(s):  
Objective Function ◽  
Root Mean Square ◽  
Mean Square ◽  
Loss Model ◽  
Percent Error ◽  
Rms Error

Penerapan Hidrograf Satuan Sintetik (HSS) Clark pada DAS Lubuk Bendahara membutuhkan analisis yanglebih detail. Data curah hujan dan pencatatan muka air otomatis (AWLR) lapangan diperlukan sebagai bahankalibrasi. Parameter kehilangan air (loss model), aliran dasar (baseflow) dan transformasi aliran (transformmethod) dalam hidrograf satuan sintetik Clark dikalibrasi dengan menggunakan program HEC-HMS. Proseskalibrasi ini menggunakan tiga metode objective function yaitu Peak Weighted Root Mean Square (RMS) Error,Percent Error Peak dan Percent Error Volume. Hasil kalibrasi menunjukkan nilai yang dihasilkanmenggunakan metode Peak-Weighted RMS Error sebesar 2,57, selisih volume -0,09% dan selisih debit puncak1,1%.

Metaheuristic data fitting methods to estimate Weibull parameters for wind speed data: a case study of Hasan Polatkan Airport

2021 ◽  
pp. 1-33
Author(s):  
A. Kaba ◽  
A. E. Suzer
Keyword(s):  
Wind Speed ◽  
Numerical Methods ◽  
Root Mean Square Error ◽  
Objective Function ◽  
Mean Square Error ◽  
Root Mean Square ◽  
Statistical Tests ◽  
Mean Square ◽  
Flight Delays

ABSTRACT Flight delays may be decreased in a predictable way if the Weibull wind speed parameters of a runway, which are an important aspect of safety during the take-off and landing phases of aircraft, can be determined. One aim of this work is to determine the wind profile of Hasan Polatkan Airport (HPA) as a case study. Numerical methods for Weibull parameter determination perform better when the average wind speed estimation is the main objective. In this paper, a novel objective function that minimises the root-mean-square error by employing the cumulative distribution function is proposed based on the genetic algorithm and particle swarm optimisation. The results are compared with well-known numerical methods, such as maximum-likelihood estimation, the empirical method, the graphical method and the equivalent energy method, as well as the available objective function. Various statistical tests in the literature are applied, such as R2, Root-Mean-Square Error (RMSE) and $\chi$ 2. In addition, the Mean Absolute Error (MAE) and total elapsed time calculated using the algorithms are compared. According to the results of the statistical tests, the proposed methods outperform others, achieving scores as high as 0.9789 and 0.9996 for the R2 test, as low as 0.0058 and 0.0057 for the RMSE test, 0.0036 and 0.0045 for the MAE test and 3.53 × 10−5 and 3.50 × 10−5 for the $\chi$ 2 test. In addition, the determination of the wind speed characteristics at HPA show that low wind speed characteristics and regimes throughout the year offer safer take-off and landing schedules for target aircraft. The principle aim of this paper is to help establish the correct orientation of new runways at HPA and maximise the capacity of the airport by minimising flight delays, which represent a significant impediment to air traffic flow.

Assessment of the performance and effects of metro-induced ground-borne vibration for mitigation measures of resilient tracks

2017 ◽  
Vol 232 (5) ◽  
pp. 1448-1463 ◽  
Author(s):  
TX Wu ◽  
HL Xing
Keyword(s):  
Root Mean Square ◽  
High Efficiency ◽  
Mitigation Measures ◽  
Mean Square ◽  
Environment Factors ◽  
The Real ◽  
Real Effects ◽  
Force Ratio ◽  
Calculation Results ◽  
Reference Track

A methodology that judges the performance and estimates the effects of metro-induced ground-borne vibration is presented for the mitigation measures of resilient tracks. Two criteria are proposed for the purpose of judgment and estimation, respectively. One is the force ratio obtained by comparing the forces transmitted to the track bed of the resilient track with those of a reference track. As the force ratio of the track bed does not vary with the excitation and environment conditions, it can be used for judging the performance of the ground-borne vibration, i.e. the inherent ability to mitigate vibration, of the resilient track. Another criterion is the overall frequency-weighted root-mean-square acceleration at the receivers. This criterion is used for the estimation of the real effects of the ground-borne vibration of a resilient track in practical conditions. Calculation results demonstrate that the practical effects of ground-borne vibration of the mitigation measures studied vary with the excitation and environment factors and tend to be more effective when the unevenness excitation is rougher or the monitoring points are closer to the source of vibration. The proposed criteria, the corresponding models developed, and the methodology presented exhibit both high efficiency in computation and great convenience for assessing the mitigation measures of resilient tracks.

A NEW METHOD FOR CALCULATING THE FRACTAL DIMENSION OF SURFACE TOPOGRAPHY

Fractals ◽  
2015 ◽  
Vol 23 (03) ◽  
pp. 1550022 ◽  
Author(s):  
XUE ZUO ◽  
HUA ZHU ◽  
YUANKAI ZHOU ◽  
YAN LI
Keyword(s):  
Fractal Dimension ◽  
Root Mean Square ◽  
Relative Error ◽  
New Method ◽  
Variation Method ◽  
Triangular Prism ◽  
Mean Square ◽  
Fractal Function ◽  
Fractal Curve ◽  
Machined Surfaces

A new method termed as three-dimensional root-mean-square (3D-RMS) method, is proposed to calculate the fractal dimension (FD) of machined surfaces. The measure of this method is the root-mean-square value of surface data, and the scale is the side length of square in the projection plane. In order to evaluate the calculation accuracy of the proposed method, the isotropic surfaces with deterministic FD are generated based on the fractional Brownian function and Weierstrass–Mandelbrot (WM) fractal function, and two kinds of anisotropic surfaces are generated by stretching or rotating a WM fractal curve. Their FDs are estimated by the proposed method, as well as differential boxing-counting (DBC) method, triangular prism surface area (TPSA) method and variation method (VM). The results show that the 3D-RMS method performs better than the other methods with a lower relative error for both isotropic and anisotropic surfaces, especially for the surfaces with dimensions higher than 2.5, since the relative error between the estimated value and its theoretical value decreases with theoretical FD. Finally, the electrodeposited surface, end-turning surface and grinding surface are chosen as examples to illustrate the application of 3D-RMS method on the real machined surfaces. This method gives a new way to accurately calculate the FD from the surface topographic data.

scholarly journals A study into the propagation of the uncertainties in nuclear data to the nuclear concentrations of nuclides in burn-up calculations

2020 ◽  
Vol 6 (3) ◽  
pp. 161-166
Author(s):  
Alexander N. Pisarev ◽  
Valerii V. Kolesov
Keyword(s):  
Neutron Flux ◽  
Root Mean Square ◽  
Estimation Method ◽  
Nuclear Data ◽  
Reaction Rates ◽  
Mean Square ◽  
Fuel Burn ◽  
Calculation Results ◽  
Effective Multiplication Factor ◽  
Effective Multiplication

The key papers on estimating the uncertainties in nuclear data deal with the influence of these uncertainties on the effective multiplication factor by introducing the so-called sensitivity factors and only some of these are concerned with the influence of such uncertainties on the life calculation results. On the other hand, the uncertainties in reaction rates, the neutron flux, and other quantities may lead to major distortions in findings, this making it important to be able to determine the influence of uncertainties on the nuclear concentrations of nuclides in their burn-up process. The possibility for the neutron flux and reaction rate uncertainties to propagate to the nuclear concentrations of nuclides obtained as part of burn-up calculations are considered using an example of a MOX-fuel PWR reactor cell. To this end, three burn-up calculation cycles were performed, and the propagation of uncertainties was analyzed. The advantages of the uncertainty estimation method implemented in the VisualBurnOut code consists in that all root-mean-square deviations are obtained as part of one calculation as the statistical method, e.g. GRS (Generation Random Sampled), requires multiple calculations. The VisualBurnOut calculation results for the root-mean-square deviations in nuclear concentrations were verified using a simple model problem. It is shown that there is a complex dependence of the propagation of the root-mean-square deviations in the nuclear concentrations of nuclides in the process of fuel burn-up, and, therefore, further studies need to aim at investigating the influence of uncertainties in nuclear data on the nuclear concentrations of nuclides.

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