Estimation of Weibull parameter with a modified weight function

1997 ◽  
Vol 12 (10) ◽  
pp. 2638-2642 ◽  
Author(s):  
B. K. Chandrasekhar
Keyword(s):  
Weight Function ◽  
Weibull Modulus ◽  
Least Square Method ◽  
Probability Of Failure ◽  
Strength Distribution ◽  
Least Square ◽  
Weight Functions ◽  
Distribution Data ◽  
Ceramic Components ◽  
Data Points

The Weibull modulus is widely used for estimating the reliability of ceramic components in engineering applications. An improvement in the evaluation of the Weibull modulus is achieved by using an appropriate weight function to the data points while fitting a straight line to the Weibull plot by the least square method. The conventional weight function is a function of the probability of failure. This paper describes an alternate method of obtaining the weight function based on first principles. This modified weight function is a function of the stress at failure rather than probability of failure. Evaluation of the two-parameter Weibull modulus was estimated on simulated strength distribution data with both the weight functions. A comparative analysis indicates that the modified weight function gives a different result than the conventional weight function. The paper also highlights the effect and importance of uncertainties in the measurement of strength on the calculated Weibull modulus.

scholarly journals Fuzzy Logic-Based Aerodynamic Modeling with Continuous Differentiability

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Ray C. Chang
Keyword(s):  
Fuzzy Logic ◽  
Atmospheric Turbulence ◽  
Model Development ◽  
Unsteady Aerodynamics ◽  
Least Square Method ◽  
Least Square ◽  
Transport Aircraft ◽  
Fuzzy Logic Algorithm ◽  
Modeling Process ◽  
Data Points

This paper presents a modeling method based on a fuzzy-logic algorithm to establish aerodynamic models by using the datasets from flight data recorder (FDR). The fuzzy-logic aerodynamic models are utilized to estimate more accurately the nonlinear unsteady aerodynamics for a transport aircraft, including the effects of atmospheric turbulence. The main objective in this paper is to present the model development and the resulting models with continuous differentiability. The uncertainty and correlation of the data points are estimated and improved by monitoring a multivariable correlation coefficient in the modeling process. The latter is increased by applying a least square method to a set of data points to train a set of modeling coefficients. A commercial transport aircraft encountered severe atmospheric turbulence twice at transonic flight in descending phase is the study case in the present paper. The robustness and nonlinear interpolation capability of the fuzzy-logic algorithm are demonstrated in predicting the degradation in performance and stability characteristics of this transport in severe atmospheric turbulence with sudden plunging motion.

Numerical Simulation Based on Meshless Formulation: Application to 2D Solid Mechanics

2012 ◽  
Author(s):  
Y. Ghozzi ◽  
C. Labergere ◽  
P. Villon
Keyword(s):  
Weight Function ◽  
Solid Mechanics ◽  
Specific Weight ◽  
Least Square ◽  
Weight Functions ◽  
Boundary Line ◽  
Moving Least Square ◽  
Simulation Based ◽  
Moving Least Square Approximation ◽  
The Galerkin Method

This paper presents the development of Meshless Methods based on Moving Least Square Approximation (MLSA) [3][10][14]. In the case of solid mechanics, the shape displacement functions are computed for each node with a centered scheme approximation [3][12] associated with a specific weight function [10]. Both interpolated and approximated weight functions are studied [10][9][15]. We propose to build a new C1 weight function based on a 2d boundary line. The Galerkin Method is used to solve the mechanical equilibrium balance problems [14]. A 2-dimensional example is presented to validate the Meshless Method.

scholarly journals Die herleiding van ’n datapuntkonsentrasie - afhanklike gewigsfunksie vir interpolasie na reënval - roosterpuntvelde

1996 ◽  
Vol 15 (4) ◽  
pp. 168-171
Author(s):  
C. J. de W. Rautenbach
Keyword(s):  
South Africa ◽  
Weight Function ◽  
Rainfall Data ◽  
Weight Functions ◽  
Distributed Data ◽  
Interpolation Algorithms ◽  
Data Field ◽  
Data Points ◽  
Field Area

Several interpolation algorithms have been developed to create homogeneous gridfields from heterogeneously distributed data. A shortcoming in most of these algorithms is the assumption that data field concentrations are fairly homogeneous over the grid field area. The method for constructing the weight functions as discussed here overcomes this problem by including a variable dependent on the concentration of data points in the weight function. A rainfall data field for South Africa is compiled by this algorithm. The concentration of climate stations in South Africa varies significantly.

scholarly journals Low-Cost GNSS-R Altimetry on a UAV for Water-Level Measurements at Arbitrary Times and Locations

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 998
Author(s):  
Kaoru Ichikawa ◽  
Takuji Ebinuma ◽  
Masanori Konda ◽  
Kei Yufu
Keyword(s):  
Water Level ◽  
Least Squares Method ◽  
Low Cost ◽  
Weighted Least Squares ◽  
Least Square Method ◽  
Satellite System ◽  
High Elevation ◽  
Least Square ◽  
Weight Functions ◽  
Weighted Least Squares Method

Together with direct Global Navigation Satellite System (GNSS) signals, the signals reflected at the water surface can be received by an unmanned aerial vehicle (UAV). From the range difference between two GNSS signal paths, the height of the UAV above the water level can be geometrically estimated using the weighted least squares method, called GNSS reflectometry (GNSS-R) altimetry. Experimental low-cost GNSS-R altimetry flights with a UAV were conducted at the coast of Lake Biwa, Japan. Although the height estimated by the GNSS-R altimeter included large short-term noises up to 8 m amplitude, it agreed well with the UAV altitude measured by the post-processed kinematic positioning. By selecting better weight functions in the least square method and using sufficient temporal averaging, the GNSS-R altimetry achieved accuracy in the order of 0.01 m if a sufficient number of GNSS satellites with high elevation angles were available. The dependency of the results on the weight functions is also discussed.

scholarly journals Cubic B-spline Least-square Method Combine with a Quadratic Weight Function for Solving Integro-Differential Equations

2020 ◽  
pp. 99-113
Author(s):  
Hameeda O. Al-Humedi ◽  
Zahraa Adnan Jameel
Keyword(s):  
Differential Equations ◽  
Weight Function ◽  
Current Method ◽  
Least Square Method ◽  
Least Square ◽  
Weakly Singular Kernel ◽  
Von Neumann ◽  
B Spline ◽  
Quadratic Weight ◽  
The Stability

In this article, a numerical scheme was implemented for solving the integro-differential equations (IDEs) with the weakly singular kernel by using a new scheme depend on the cubic B-spline least-square method and a quadratic B-spline as a weight function. The numerical results are in suitable agreement with the exact solutions via calculating L2 and L∞ norms errors. Theoretically, we discussed the stability evaluation of the current method using the Von-Neumann method, which explained that this technique is unconditionally stable.

Direct Assessment of Effective Renal Plasma Flow from Renoscintigraphy with a Gamma Camera and an On-Line Computer

1981 ◽  
Vol 20 (06) ◽  
pp. 274-278
Author(s):  
J. Liniecki ◽  
J. Bialobrzeski ◽  
Ewa Mlodkowska ◽  
M. J. Surma
Keyword(s):  
Count Rate ◽  
Renal Plasma Flow ◽  
Early Period ◽  
Least Square Method ◽  
Least Square ◽  
Uptake Coefficient ◽  
Positive Linear Correlation ◽  
On Line ◽  
Best Fit ◽  
Plasma Activity

A concept of a kidney uptake coefficient (UC) of 131I-o-hippurate was developed by analogy from the corresponding kidney clearance of blood plasma in the early period after injection of the hippurate. The UC for each kidney was defined as the count-rate over its ROI at a time shorter than the peak in the renoscintigraphic curve divided by the integral of the count-rate curve over the "blood"-ROI. A procedure for normalization of both curves against each other was also developed. The total kidney clearance of the hippurate was determined from the function of plasma activity concentration vs. time after a single injection; the determinations were made at 5, 10, 15, 20, 30, 45, 60, 75 and 90 min after intravenous administration of 131I-o-hippurate and the best-fit curve was obtained by means of the least-square method. When the UC was related to the absolute value of the clearance a positive linear correlation was found (r = 0.922, ρ > 0.99). Using this regression equation the clearance could be estimated in reverse from the uptake coefficient calculated solely on the basis of the renoscintigraphic curves without blood sampling. The errors of the estimate are compatible with the requirement of a fast appraisal of renal function for purposes of clinical diagknosis.

PENGARUH KNOWLEDGE MANAGEMENT, KOMPETENSI, MOTIVASI TERHADAP KINERJA KARYAWAN

2015 ◽  
Vol 5 (2) ◽  
pp. 1
Author(s):  
Miftahol Arifin
Keyword(s):  
Knowledge Management ◽  
Linear Regression ◽  
Significant Influence ◽  
Employee Performance ◽  
Least Square Method ◽  
Least Square ◽  
Analysis Tool ◽  
Ordinary Least Square ◽  
Competence Motivation ◽  
Performance Analyze

The purpose of this research is to analyze the influence of knowledge management on employee performance, analyze the effect of competence on employee performance, analyze the influence of motivation on employee performance). In this study, samples taken are structural employees PT.centris Kingdom Taxi Yogyakarta. The analysis tool in this study using multiple linear regression with Ordinary Least Square method (OLS). The conclusion of this study showed that the variables of knowledge management has a significant influence on employee performance, competence variables have an influence on employee performance, motivation variables have an influence on employee performance, The analysis showed that the variables of knowledge management, competence, motivation on employee performance.Keywords: knowledge management, competence, motivation, employee performance.

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