Stiffness matrix method for analysis of torsionally loaded piles in multi-layered soil

2021 ◽  
pp. 1-19
Author(s):  
Carlos A. Vega-Posada
Keyword(s):  
Stiffness Matrix ◽  
Soil Layer ◽  
Quadratic Function ◽  
Practical Method ◽  
Transformation Method ◽  
Layered Soil ◽  
Structural Element ◽  
The Matrix ◽  
Governing Differential Equation ◽  
Air Interfaces

A new, simple, and practical method to investigate the response of torsionally loaded piles on homogeneous or non-homogeneous multi-layered elastic soil is developed. The soil non-homogeneity is accounted for by assuming for each layer a shear modulus distribution that fits a quadratic function. The analysis of piles in multi-layered soil is carried out by subdividing the pile, at the soil-soil layer and soil-air interfaces, into multiple elements, and then using conventional matrix methods -such as those commonly implemented in structural analysis- to connect them. The governing differential equation (GDE) of an individual structural element is solved using the Differential Transformation Method (DTM). Next, the stiffness matrix is derived by applying compatibility conditions at the ends of the element. Piles partially or fully embedded in multiple layers and subjected to torsion can be analyzed in a simple manner with the proposed formulation -a tedious endeavor with other available solutions. Finally, explicit expressions for the coefficients of the matrix are provided. Four examples are presented to show the simplicity, accuracy, and capabilities of the proposed formulation.

scholarly journals A new method for identifying the role of marital preferences at shaping marriage patterns

2021 ◽  
pp. 1-27
Author(s):  
Anna Naszodi ◽  
Francisco Mendonca
Keyword(s):  
Contingency Table ◽  
Transformation Method ◽  
New Method ◽  
Marriage Patterns ◽  
The Us ◽  
Analytical Properties ◽  
The Matrix ◽  
Transformation Methods

Abstract We develop a method which assumes that marital preferences are characterized either by the scalar-valued measure proposed by Liu and Lu, or by the matrix-valued generalized Liu–Lu measure. The new method transforms an observed contingency table into a counterfactual table while preserving its (generalized) Liu–Lu value. After exploring some analytical properties of the new method, we illustrate its application by decomposing changes in the prevalence of homogamy in the US between 1980 and 2010. We perform this decomposition with two alternative transformation methods as well where both methods capture preferences differently from Liu and Lu. Finally, we use survey evidence to support our claim that out of the three considered methods, the new transformation method is the most suitable for identifying the role of marital preferences at shaping marriage patterns. These data are also in favor of measuring assortativity in preferences à la Liu and Lu.

scholarly journals Dilution of QuEChERS Extracts Without Cleanup Improves Results in the UHPLC-MS/MS Multiresidue Analysis of Pesticides in Tomato

2021 ◽  
Author(s):  
Fabiane M. Stringhini ◽  
Lucila C. Ribeiro ◽  
Graziela I. Rocha ◽  
Juliana D. de B. Kuntz ◽  
Renato Zanella ◽  
...  
Keyword(s):  
Matrix Effect ◽  
Practical Method ◽  
Analysis Method ◽  
Multiresidue Analysis ◽  
Limit Of Quantification ◽  
Chromatography Tandem Mass Spectrometry ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Ultrahigh Performance Liquid Chromatography ◽  
Positive Results

AbstractTomato is well-known to be one of the most cultivated and consumed vegetables worldwide and frequently contain pesticide residues. Therefore, a simple multiresidue method was established and validated to determine 129 pesticides and metabolites in tomato samples using a modified acetate QuEChERS without cleanup for sample preparation and determination by ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Dilution of the raw extract in different proportions of mobile phase was evaluated and a dilution of 10 times presented adequate results improving analysis performance while minimizing the matrix effect. Validation performed according to SANTE guideline presented satisfactory results. Practical method limit of quantification was 0.01 mg kg−1 for most compounds. Recoveries between 70 and 120% with precision ≤ 20% were found for most compounds and spike levels evaluated. Matrix effect results were not significant for most part of compounds. Method proved to be simple, robust, and effective to be applied in routine analysis. Method applicability was performed by analysis of samples commercialized in Brazil and positive results were found demonstrating the importance of the proposed method.

The distribution of fibronectin, laminin and entactin in the neurulating rat embryo studied by indirect immunofluorescence

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 95-112
Author(s):  
Fiona Tuckett ◽  
Gillian M. Morriss-Kay
Keyword(s):  
Extracellular Matrix ◽  
Indirect Immunofluorescence ◽  
Active Sites ◽  
Polyclonal Antibodies ◽  
Tube Formation ◽  
Basement Membranes ◽  
General Distribution ◽  
Rat Embryo ◽  
Structural Element ◽  
The Matrix

This paper forms part of our study of the extracellular matrix and its role in the morphogenesis of the brain during the period of neurulation in the rat embryo. Using indirect immunofluorescence with polyclonal antibodies, we present here a descriptive study of the distribution of the matrix glycoproteins fibronectin, laminin and entactin. The observed distribution of the fibronectin matrix implicates it in providing a structural element in several morphologically active sites; in addition our observations support the previously suggested involvement of fibronectin in the migration of neural crest cells. Entactin was present only in the basement membranes in conjunction with laminin which was not itself confined to these regions. Laminin was also identified within the mesenchymal extracellular matrix, and its general distribution confirms the previously documented role of laminin in maintaining epithelial structure and organization. No patterning in the distribution of these three glycoproteins could be correlated with the change in shape of the neural epithelium associated with either tube formation or neuromere morphogenesis.

scholarly journals An Analytical Study of Weakly Nonlinear Dynamics of a Walters’ Liquid B around a Flexible Sheet Undergoing Super Linear Stretching

2012 ◽  
Vol 2012 ◽  
pp. 1-13
Author(s):  
P. G. Siddheshwar ◽  
A. Chan ◽  
U. S. Mahabaleswar
Keyword(s):  
Nonlinear Dynamics ◽  
Differential Equation ◽  
Boundary Layer ◽  
Analytical Study ◽  
Stretching Sheet ◽  
Quadratic Function ◽  
Weakly Nonlinear ◽  
Governing Differential Equation ◽  
Layer Flow ◽  
Analytical Expressions

The paper discusses the boundary layer flow of Walters’ liquid B over a stretching sheet. The stretching is assumed to be a quadratic function of the coordinate along the direction of stretching. The study encompasses within its realm both Walters’ liquid B and second order liquid. The velocity distribution is obtained by solving the nonlinear governing differential equation. Analytical expressions are obtained for stream function and velocity components as functions of the viscoelastic and stretching related parameters. It is shown that the viscoelasticity goes hand in hand with quadratic stretching in enhancing the lifting of the liquid as we go along the sheet.

Buckling of Piles in Layered Soils by Transfer Matrix Method

2021 ◽  
pp. 2150109
Author(s):  
Lu Zheng ◽  
Tao Deng ◽  
Qijian Liu
Keyword(s):  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Present Method ◽  
Soil Layer ◽  
Layered Soils ◽  
Subgrade Reaction ◽  
Soil Stiffness ◽  
Governing Differential Equation ◽  
The Stability

The transfer matrix method is applied to the buckling of end-bearing piles partially or fully embedded in a layered elastic medium with a constant coefficient of subgrade reaction for each layer. The solution of the governing differential equation for each pile segment can be expressed as the product of a fourth-order matrix and a coefficient determinant. Using the transfer matrix method and combining the boundary conditions at both ends of the pile, the buckling load is obtained by solving the eigenvalue equation. A parametric study is performed to investigate the effects of the properties of the soil–pile system on the stability capacity of the pile. It is shown that the effects of the embedment ratio, soil layer thickness, and soil stiffness on the buckling of piles are quite significant. Several calculation examples are presented to verify the present method.

A New Quadratic Membrane Element

2004 ◽  
Vol 261-263 ◽  
pp. 537-542
Author(s):  
Shui Lin Wang ◽  
Xia Ting Feng ◽  
Xiu Run Ge
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stiffness Matrix ◽  
Quadratic Function ◽  
High Accuracy ◽  
Displacement Function ◽  
Test Problems ◽  
Interpolation Function ◽  
Membrane Element ◽  
Quadrilateral Element

In finite element method, the order of complete polynomial of the interpolation function is related to the number of nodes in the element. This paper presents a four-node quadrilateral element with quadratic function on it. The presented displacement functions maintain C0-continuity. Meanwhile, the element stiffness matrix is derived from the displacement functions. Test problems show that high accuracy can be achieved by the use of the new displacement function on the element.

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