Determination of growth modes via spectroscopy: new simple analytical models

2005 ◽  
Vol 240 (1-4) ◽  
pp. 189-196 ◽  
Author(s):  
Qiang Fu ◽  
Thomas Wagner
Keyword(s):  
Analytical Models ◽  
Growth Modes

A New Approach for Determining Joint Stiffness of Bolted Joints

2014 ◽  
Vol 670-671 ◽  
pp. 1041-1044 ◽  
Author(s):  
Xi Wang Wang ◽  
Xiao Yang Li ◽  
Lin Lin Zhang ◽  
Xiao Guang Wang
Keyword(s):  
Accurate Determination ◽  
Joint Stiffness ◽  
Fatigue Loading ◽  
Bolted Joints ◽  
Analytical Models ◽  
Bolted Connection ◽  
New Approach ◽  
Axisymmetric Model ◽  
Force Equilibrium

Joint member stiffness in a bolted connection directly influence the safety of a design in regard to both static and fatigue loading as well as in the prevention of separation in the connection. Thus, the accurate determination of the stiffness is of extreme importance to predict the behavior of bolted assemblies. In this paper, An analytical 3D axisymmetric model of bolted joints is proposed to obtain the joint stiffness of Bolted Joints. Considering many different analytical models have been proposed to calculate the joint stiffness, the expression based force equilibrium can be a easy way to choose the best expression for the joint stiffness as a judgment criteria.

scholarly journals Using Bayesian Model Selection to Advise Neutron Reflectometry Analysis from Langmuir-Blodgett Monolayers

2019 ◽  
Author(s):  
Andrew McCluskey ◽  
Tom Arnold ◽  
Joshaniel F. K. Cooper ◽  
Tim Snow
Keyword(s):  
Experimental Data ◽  
Soft Matter ◽  
General Framework ◽  
Neutron Reflectometry ◽  
Analytical Models ◽  
Colloid Interface ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Generic Framework

The analysis of neutron and X-ray reflectometry data is important for the study of interfacial soft matter structures. However, there is still substantial discussion regarding the analytical models<br>that should be used to rationalise relflectometry data. In this work, we outline a robust and generic framework for the determination of the evidence for a particular model given experimental data, by<br>applying Bayesian logic. We apply this framework to the study of Langmuir-Blodgett monolayers by considering three possible analytical models from a recently published investigation [Campbell et al., J. Colloid Interface Sci, 2018, 531, 98]. From this, we can determine which model has the most evidence given the experimental data, and show the effect that different isotopic contrasts of neutron reflectometry will have on this. We believe that this general framework could become an important component of neutron and X-ray reflectometry data analysis, and hope others more regularly consider the relative evidence for their analytical models.<br>

scholarly journals Failure Modes and Resistance of Perforated Steel Rib Shear Connectors under Uplift Forces

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Xiaoqing Xu ◽  
Yuqing Liu
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Analytical Models ◽  
Shear Connectors ◽  
Steel Bar ◽  
Concrete Damage ◽  
Uplift Resistance ◽  
Transverse Steel ◽  
Uplift Forces

In recent years, there is a rapid increase in the application of perforated steel rib shear connectors in steel and concrete composite structures. The connectors must not only ensure shear transfer but also sufficient uplift resistance. The shear behavior of connectors has been extensively investigated. However, studies on uplift resistance are lacking so far. Therefore, three push-out test specimens were tested to investigate the shear and tension behavior of perforated L-shaped and plain steel rib shear connectors. The failure modes of connectors were analyzed, and analytical models for the determination of uplift resistance were derived based on test results. The results showed that the ductility of perforated steel rib shear connectors under uplift force was smaller than that under shear force, and more severe concrete damage surrounding the rib and larger bending deformation of transverse steel bar was observed. The rib flange of L-shaped perforated rib has a significant contribution to the uplift resistance. It was suggested to increase the rib height of L-shaped rib to avoid the horizontal crack at the height of the rib flange. The validity of the proposed analytical models was confirmed by comparing the failure modes and capacities of specimens.

Experimental and Numerical Analysis of Wood-Framed Buildings

2018 ◽  
Vol 878 ◽  
pp. 13-17
Author(s):  
Jaroslaw Malesza ◽  
Czeslaw Miedziałowski
Keyword(s):  
Vertical Displacement ◽  
Analytical Models ◽  
Industrial Plant ◽  
Building Structure ◽  
Shell Elements ◽  
Multistory Buildings ◽  
Precise Analysis ◽  
Modular Technology ◽  
Story Building

Paper presents current technologies and building structure used in wood-framed multistory buildings and also refers to calculation methods of strains and stresses. Structure of these buildings is recently based on modular technology. Elements in the form of module are constructed in the industrial plant and then delivered to the site for assembling. The wood-framed building structure undergoes significant deformations relevant to changes of moisture content in material and resulted from load acting perpendicular to the grain direction in wood. In four story building the vertical displacement of the top floor has been estimated to over 80 mm. FEM model with application of the shell elements in description of posts, beams and sheathing and applying the beam finite elements in description of linking fasteners is used in stress evaluation in structure. The model permits for precise analysis of stresses in overloaded parts of structure distinguishing to the other simplified analytical models of analyses. Analytical model leads to determination of stresses under typical exploitation standard loadings and in result of non-typical loadings arising at the time of module handling within assembling.

scholarly journals On the Force Drop Off Phenomenon in Shaker Testing in Experimental Modal Analysis

2002 ◽  
Vol 9 (4-5) ◽  
pp. 165-175 ◽  
Author(s):  
Paulo Sergio Varoto ◽  
Leopoldo Pisanelli Rodrigues de Oliveira
Keyword(s):  
Input Signal ◽  
Modal Testing ◽  
Analytical Models ◽  
Vibration Exciter ◽  
Electromechanical Device ◽  
Vibration Tests ◽  
Operational Modes ◽  
Electrodynamic Vibration ◽  
Force Drop

The Electrodynamic Vibration Exciter (shakers) has been one of the most employed excitation sources in modal tests. The shaker is an electromechanical device that provides a mechanical motion due to the input signal sent to its coil. Despite being widely used, it is well known that the shaker interacts with the structure under test. In particular, when the structure passes through a given resonance, the force delivered by the shaker abruptly decreases, causing the so called drop off phenomenon. This paper aims to study this force drop off phenomenon in the single shaker modal testing. Analytical models are developed to help in understanding the physical principles involved in the interaction between the shaker and the structure under test. Experimental analyses are performed using different shakers as well as excitation signals, in order to evaluate the effects of the input signal, as well as the power amplifier operational modes, on the structure dynamics. Preliminary tests revealed that significant distortions might occur during vibration tests using shakers and these distortions significantly affect the determination of the structure response.

scholarly journals FRP-Confined Concrete Columns: A New Procedure for Evaluating the Performance of Square and Circular Sections

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Marinella Fossetti ◽  
Francesco Basone ◽  
Giuseppe D’Arenzo ◽  
Giuseppe Macaluso ◽  
Alfio Francesco Siciliano
Keyword(s):  
Concrete Columns ◽  
Confined Concrete ◽  
Analytical Models ◽  
Dissipated Energy ◽  
Element Analysis ◽  
The Many ◽  
Open Question ◽  
Semiempirical Models ◽  
Strength And Ductility

In the last few decades, the upgrading of existing reinforced concrete columns with the use of FRP jackets has met with increasing interest for its effectiveness and ease of application. The use of these kinds of jackets ensures an improvement of the affected column in terms of strength and ductility; however, the prediction of behavior of columns wrapped with FRP jackets is still an open question because of the many parameters that influence the effectiveness of the upgrading technique, and several semiempirical models are proposed. Because these models are often only applicable to specific cases, in this paper, a generalized criterion for the determination of the increase in strength, in ductility, and in dissipated energy for varying corner radius ratios of the cross section and fiber volumetric ratios is shown. Numerical results using a finite element analysis, calibrated on the basis of experimental data available in the literature, are carried out to calibrate the new analytical models. A comparison with some available models confirms the reliability of the proposed procedure.

scholarly journals Analytical Models for Determination of Complex Permittivity

1997 ◽  
Vol 15 ◽  
pp. 109-139
Author(s):  
J. A. K. Adopley ◽  
D. G. Dudley ◽  
R. Taherian
Keyword(s):  
Complex Permittivity ◽  
Analytical Models

Explicit Determination of Reserves for Variable-Bottomhole-Pressure Conditions in Gas Rate-Transient Analysis

SPE Journal ◽  
2019 ◽  
Vol 25 (01) ◽  
pp. 369-390 ◽  
Author(s):  
Yang Wang ◽  
Luis F. Ayala
Keyword(s):  
Transient Analysis ◽  
Gas Flow ◽  
Hyperbolic Equations ◽  
Analytical Models ◽  
Pvt Properties ◽  
Reservoir Properties ◽  
Rate Transient Analysis ◽  
Straight Line ◽  
Bottomhole Pressure

Summary Current rate-transient-analysis tools for gas wells producing under boundary-dominated-flow (BDF) conditions largely rely on the deployment of the Arps empirical decline models (Arps 1945), or liquid-based analytical models rewritten in terms of pseudofunctions. Recently, Stumpf and Ayala (2016) demonstrated that, contrary to common practice, decline exponents (b) used in Arps’ hyperbolic equations when applied to gas-well analysis can be rigorously estimated before any field-production data are collected. This determination is solely dependent on gas pressure/volume/temperature (PVT) properties and prevailing constant-bottomhole-pressure (BHP) specification for volumetric, single-phase gas-flow conditions. In the study, we extend that work to a more-realistic variable-BHP condition, which is the most common production-specification condition, in terms of the ratio of changing BHP to average reservoir pressure. The decline exponent (b) is thus rederived, and it is shown that under such conditions, variable BHP hyperbolic decline coefficients become solely dependent on fluid PVT properties and take their largest possible magnitude compared with constant-BHP production. Step-by-step analysis procedures are presented that enable explicit and straightforward estimation of original gas in place (OGIP) and other reservoir properties by universal-type-curve and straight-line analysis. Finally, several cases using simulated and field data are discussed in detail to validate the capabilities of the proposed approach.

The interaction of tube waves with borehole fractures, Part II: Analytical models

Geophysics ◽  
1998 ◽  
Vol 63 (3) ◽  
pp. 809-815 ◽  
Author(s):  
Sergio Kostek ◽  
David Linton Johnson ◽  
Kenneth W. Winkler ◽  
Brian E. Hornby
Keyword(s):  
Finite Difference ◽  
Analytical Models ◽  
Stoneley Wave ◽  
Single Fracture ◽  
Elastic Model ◽  
Formation Model ◽  
Wave Reflections ◽  
Fracture Width ◽  
Fracture Apertures

We develop a series of analytical models that can be used to interpret Stoneley‐wave reflections from fractures intersecting a borehole, thus facilitating the determination of effective fracture apertures from logs. The first model considers the combined effects of borehole enlargements (e.g., washouts) and fractures on the reflection coefficient of Stoneley waves. The result is expressed in terms of the washout volume, which can be obtained from a caliper log, as well as the fracture width. The predictions of this model are in excellent agreement with finite‐difference calculations. Next we develop an analytical elastic model that generalizes the rigid formation model. It also agrees with finite‐difference calculations. Finally, we establish the equivalence between a closely spaced multiple fracture and a permeable medium. In all the examples, the generalization of the result for the single fracture in a rigid formation can be accomplished with standard logging measurements.

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