Estimation of Ultrasound Attenuation and its Application to Tissue Heterogeneity Study Using Nonlinear Least Square Data Fitting

2009 ◽  
Author(s):  
Xiaoying Li ◽  
Dong Liu
Keyword(s):  
Data Fitting ◽  
Least Square ◽  
Tissue Heterogeneity ◽  
Ultrasound Attenuation

scholarly journals Measurement Data Fitting Based on Moving Least Squares Method

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Huaiqing Zhang ◽  
Chunxian Guo ◽  
Xiangfeng Su ◽  
Chuanbao Zhu
Keyword(s):  
Data Processing ◽  
Least Squares ◽  
Least Squares Method ◽  
Weighted Least Squares ◽  
Measurement Data ◽  
Data Fitting ◽  
Local Approximation ◽  
Least Square ◽  
Superior Performance ◽  
Moving Least Squares

In the electromagnetic field measurement data postprocessing, this paper introduced the moving least squares (MLS) approximation method. The MLS combines the concept of moving window and compact support weighting functions. It can be regarded as a combination of weighted least squares and segmented least square. The MLS not only can acquire higher precision even with low order basis functions, but also has good stability due to its local approximation scheme. An attractive property of MLS is its flexible adjustment ability. Therefore, the data fitting can be easily adjusted by tuning weighting function’s parameters. Numerical examples and measurement data processing reveal its superior performance in curves fitting and surface construction. So the MLS is a promising method for measurement data processing.

scholarly journals Proposal for a Random-based Algorithm to Solve Data-fitting Problems

2020 ◽  
Author(s):  
Giorgio Gambirasio
Keyword(s):  
Differential Calculus ◽  
Least Square Method ◽  
Data Fitting ◽  
Least Square ◽  
Preceding Article ◽  
Python Language ◽  
Experimental Algorithm ◽  
Linear Least Square

This preprint is a complement to a preceding article. Since error-squaring exaggerates the influence of outliers in the linear least square method, a more natural procedure to avoid mutual cancellation of errors would be taking absolute values of errors instead. However, such a choice would prevent using differential calculus. It is then suggested that calculus be replaced by an algorithm which selects the best line from a set of random-generated lines. The proposal has been tested with an experimental algorithm written in Python language and found to work well.

Successive Generation of Chebychev Approximation Solution

1965 ◽  
Vol 87 (1) ◽  
pp. 17-22
Author(s):  
Masanao Aoki
Keyword(s):  
Least Squares ◽  
Recursive Algorithm ◽  
Linear Equations ◽  
Approximation Problem ◽  
Data Fitting ◽  
Least Square ◽  
Approximation Solution ◽  
Absolute Deviation ◽  
Least Square Estimate ◽  
Chebychev Approximation

Problems of filtering and prediction, which are significant parts of many control problems, can be treated as those of data-fitting, usually by the method of least squares. Then, the least-square data-fitting is essentially the process by which a best approximate solution is obtained, in the sense of least squares of deviation, of a system of overdetermined linear equations. The same problem is known as the Chebychev approximation problem when the absolute deviation is used as the measure of goodness of approximation. The paper gives a recursive algorithm for the Chebychev approximation problem by modifying a nonrecursive algorithm of Zuhovickii and Stiefel. An example of estimation processes is given in which the Chebychev approximation method gives an estimate whose variance is smaller than that of the least square estimate.

Least-square refinement of structure parameters from CBED integrated intensities: application to determination of temperature factors in Y BA2CU3O7

1992 ◽  
Vol 50 (2) ◽  
pp. 1456-1457
Author(s):  
Kjersti Gjønnes ◽  
Jon Gjønnes
Keyword(s):  
Least Square ◽  
Measured Intensity ◽  
Structure Information ◽  
Accurate Temperature ◽  
Least Square Fit ◽  
Case Application ◽  
Integrated Intensities ◽  
Temperature Factors ◽  
Narrow Bands

Electron diffraction intensities can be obtained at large scattering angles (sinθ/λ ≥ 2.0), and thus structure information can be collected in regions of reciprocal space that are not accessable with other diffraction methods. LACBED intensities in this range can be utilized for determination of accurate temperature factors or for refinement of coordinates. Such high index reflections can usually be treated kinematically or as a pertubed two-beam case. Application to Y Ba2Cu3O7 shows that a least square refinememt based on integrated intensities can determine temperature factors or coordinates.LACBED patterns taken in the (00l) systematic row show an easily recognisable pattern of narrow bands from reflections in the range 15 < l < 40 (figure 1). Integrated intensities obtained from measured intensity profiles after subtraction of inelastic background (figure 2) were used in the least square fit for determination of temperature factors and refinement of z-coordinates for the Ba- and Cu-atoms.

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.

Ease of Doing Business and Its Impact on Inward FDI

2018 ◽  
Vol 1 (1) ◽  
pp. 52 ◽  
Author(s):  
Mohamed Tareq Hossain ◽  
Zubair Hassan ◽  
Sumaiya Shafiq ◽  
Abdul Basit
Keyword(s):  
Regression Model ◽  
Causal Relationship ◽  
World Bank ◽  
Least Square ◽  
Doing Business ◽  
Least Square Regression ◽  
Foreign Countries ◽  
Ease Of Doing Business ◽  
The Impact ◽  
Starting A Business

This study investigates the impact of Ease of Doing Business on Inward FDI over the period from 2011 to 2015 across the globe. This study measures ease of doing business using starting a business, getting credit, registering property, paying taxes and enforcing contracts. The research used a sample of 177 countries from 190 countries listed in World Bank. Least square regression model via E-views software used to examine causal relationship. The study found that ease of doing business indicators ‘Enforcing Contracts’ was found to have a positive significant impact on Inward FDI. Nevertheless, ‘Getting Credit’ and ‘Registering Property’ were found to have a negative significant impact on Inward FDI. However, ‘Starting a Business’ and ‘Paying Taxes’ have no significant impact on Inward FDI in the studied timeframe of this research. The findings of the study suggested the ease of doing business enables inward FDI through better contract enforcements, getting credit and registering property. The findings of the research will assist international managers and companies to know the importance of ease of doing business when investing in foreign countries through FDI.

Sign in / Sign up

Export Citation Format

Share Document