A Coupled FE-TLE Model for the Prediction of Subway Train-Induced Ground-Borne Vibrations

2012 ◽  
Vol 256-259 ◽  
pp. 1221-1225
Author(s):  
He Sheng Tang ◽  
Jie Wang ◽  
Jia Wu Shi
Keyword(s):  
Finite Element ◽  
Thin Layer ◽  
Numerical Models ◽  
Dynamic Interaction ◽  
Tunnel Structure ◽  
Layered Soils ◽  
In Situ Experiments ◽  
Subway Train ◽  
Tunnel System

A coupled finite element–thin layer element (FE-TLE) model for the prediction of subway induced vibrations was developed. With this model, the soil-tunnel system is divided into two parts, i.e., the tunnel structure and layered soil with a tunnel type hole. The tunnel structure is simulated by finite elements and the layered soils with hole by thin layer elements. The model fully accounts for the dynamic interaction between the tunnel and the soil. The numerical models for train-induced ground-borne vibrations were validated by in-situ experiments.

scholarly journals Advanced experimental approaches to marine water-column biogeochemical processes

2017 ◽  
Vol 75 (1) ◽  
pp. 30-42 ◽  
Author(s):  
Louis Legendre ◽  
Richard B Rivkin ◽  
Nianzhi Jiao
Keyword(s):  
Water Column ◽  
Numerical Models ◽  
Free Water ◽  
Sea Surface ◽  
Biogeochemical Processes ◽  
In Situ Experiments ◽  
Technological Developments ◽  
Approaches To Study ◽  
Experimental Approaches

Abstract This “Food for Thought” article examines the potential uses of several novel scientific and technological developments, which are currently available or being developed, to significantly advance or supplement existing experimental approaches to study water-column biogeochemical processes (WCB-processes). After examining the complementary roles of observation, experiments and numerical models to study WCB-processes, we focus on the main experimental approaches of free-water in situ experiments, and at-sea and on-land meso- and macrocosms. We identify some of the incompletely resolved aspects of marine WCB-processes, and explore advanced experimental approaches that could be used to reduce their uncertainties. We examine three such approaches: free-water experiments of lengthened duration using bioArgo floats and gliders, at-sea mesocosms deployed several 100s m below the sea-surface using new biogeochemical sensors, and 50 m-tall on-land macrocosms. These approaches could lead to significant progress in concepts related to marine WCB-processes.

scholarly journals Investigating tool engagement in groundwood pulping: finite element modelling and in-situ observations at the microscale

Holzforschung ◽  
2020 ◽  
Vol 74 (5) ◽  
pp. 477-487 ◽  
Author(s):  
Jenny Carlsson ◽  
Magnus Heldin ◽  
Per Isaksson ◽  
Urban Wiklund
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
X Ray ◽  
Tool Geometries ◽  
Commercial Use ◽  
X Ray Computed ◽  
In Situ Observations ◽  
Underlying Mechanisms

AbstractWith industrial groundwood pulping processes relying on carefully designed grit surfaces being developed for commercial use, it is increasingly important to understand the mechanisms occurring in the contact between wood and tool. We present a methodology to experimentally and numerically analyse the effect of different tool geometries on the groundwood pulping defibration process. Using a combination of high-resolution experimental and numerical methods, including finite element (FE) models, digital volume correlation (DVC) of synchrotron radiation-based X-ray computed tomography (CT) of initial grinding and lab-scale grinding experiments, this paper aims to study such mechanisms. Three different asperity geometries were studied in FE simulations and in grinding of wood from Norway spruce. We found a good correlation between strains obtained from FE models and strains calculated using DVC from stacks of CT images of initial grinding. We also correlate the strains obtained from numerical models to the integrity of the separated fibres in lab-scale grinding experiments. In conclusion, we found that, by modifying the asperity geometries, it is, to some extent, possible to control the underlying mechanisms, enabling development of better tools in terms of efficiency, quality of the fibres and stability of the groundwood pulping process.

Finite Element Model of a Cell Incorporating Cell Membrane, Cytoskeletal Structure and Intracellular Fluid Pressure

2002 ◽  
Author(s):  
Vidyashankar Venkatesan ◽  
Nilay Mukherjee
Keyword(s):  
Finite Element ◽  
Compressive Loading ◽  
Fluid Pressure ◽  
Element Model ◽  
Structural Components ◽  
Element Analysis ◽  
In Situ Experiments ◽  
A Cell

Compressive loading is intrinsic to certain tissues in our body like articular cartilage and bone (1). In situ experiments in cartilage suggest that chondrocytes can undergo significant deformation due to compressive loading on the tissue (2). In situ and isolated cell experiments have concluded that cells are quite resilient to compressive loading, aspiration etc. and exhibit a moduli in the range of 0.6 to 2 kPa (3). However, few studies have attempted to understand the compressive behavior of cells in terms of its structural components. The structural components of a cell consist of a membrane and a dense network of at least three elements (actin, microtubules and intermediate filaments). Using finite element analysis techniques we wanted to explore the role of these structural components in determining the ability of the cell to withstand compression.

scholarly journals Versatile Spectroelectrochemical Cell for in Situ Experiments: Development, Applications and Electrochemical Behavior

2020 ◽  
Author(s):  
José L. Bott-Neto ◽  
Marta V.F. Rodrigues ◽  
Mariana C. Silva ◽  
Evaldo Batista Carneiro Neto ◽  
Gabriel Wosiak ◽  
...  
Keyword(s):  
Thin Layer ◽  
Science And Technology ◽  
Computational Experiments ◽  
Spectroscopic Techniques ◽  
Interfacial Processes ◽  
Electrochemical Processes ◽  
In Situ Experiments ◽  
Conventional Cell ◽  
Development Applications

<p><b>Abstract:</b> (Photo)electrochemical processes are involved in many fields of science and technology. The use of spectroscopic techniques coupled to (photo)electrochemistry, are mandatory to get information about interfacial processes on scale ranges from millimeters to the nanoscale. The development of spectroelectrochemical cells (SEC) contribute to the progress of the field of (photo)electrochemistry and its impact in science and technology. Therefore, in this work, we describe in detail the development of a versatile SEC that can be used for several <i>in situ</i> techniques. We performed electrochemical and computational experiments to analyze the response of our SEC as a function of the working electrode size, position and distance to the window. We found that our SEC behaves as the conventional cell when the electrode is far from the window. However, important differences arise in the thin layer configuration. The computational experiments suggest that to mitigate these problems, it is important to perform <i>in situ</i> experiments in the thin layer configuration using electrodes as small as possible.</p>

scholarly journals Versatile Spectroelectrochemical Cell for in Situ Experiments: Development, Applications and Electrochemical Behavior

2020 ◽  
Author(s):  
José L. Bott-Neto ◽  
Marta V.F. Rodrigues ◽  
Mariana C. Silva ◽  
Evaldo Batista Carneiro Neto ◽  
Gabriel Wosiak ◽  
...  
Keyword(s):  
Thin Layer ◽  
Science And Technology ◽  
Computational Experiments ◽  
Spectroscopic Techniques ◽  
Interfacial Processes ◽  
Electrochemical Processes ◽  
In Situ Experiments ◽  
Conventional Cell ◽  
Development Applications

<p><b>Abstract:</b> (Photo)electrochemical processes are involved in many fields of science and technology. The use of spectroscopic techniques coupled to (photo)electrochemistry, are mandatory to get information about interfacial processes on scale ranges from millimeters to the nanoscale. The development of spectroelectrochemical cells (SEC) contribute to the progress of the field of (photo)electrochemistry and its impact in science and technology. Therefore, in this work, we describe in detail the development of a versatile SEC that can be used for several <i>in situ</i> techniques. We performed electrochemical and computational experiments to analyze the response of our SEC as a function of the working electrode size, position and distance to the window. We found that our SEC behaves as the conventional cell when the electrode is far from the window. However, important differences arise in the thin layer configuration. The computational experiments suggest that to mitigate these problems, it is important to perform <i>in situ</i> experiments in the thin layer configuration using electrodes as small as possible.</p>

scholarly journals Effect of unsteady wind on drifting snow: first investigations

2002 ◽  
Vol 2 (3/4) ◽  
pp. 129-136 ◽  
Author(s):  
J.-L. Michaux ◽  
F. Naaim-Bouvet ◽  
M. Naaim ◽  
M. Lehning ◽  
G. Guyomarc’h
Keyword(s):  
Wind Tunnel ◽  
Numerical Models ◽  
Wind Gust ◽  
Strong Wind ◽  
Blowing Snow ◽  
Wind Tunnel Experiments ◽  
Drifting Snow ◽  
In Situ Experiments

Abstract. Wind is not always a steady flow. It can oscillate, producing blasts. However, most of the current numerical models of drifting snow are constrained by one major assumption: forcing winds are steady and uniform. Moreover, very few studies have been done to verify this hypothesis, because of the lack of available instrumentation and measurement difficulties. Therefore, too little is known about the possible role of wind gust in drifting snow. In order to better understand the effect of unsteady winds, we have performed both experiments at the climatic wind tunnel at the CSTB (Centre Scientifique et Technique des Bâtiments) in Nantes, France, and in situ experiments on our experimental high-altitude site, at the Lac Blanc Pass. These experiments were carried out collaboratively with Cemagref (France), Météo-France, and the IFENA (Switzerland). Through the wind tunnel experiments, we found that drifting snow is in a state of permanent disequilibrium in the presence of fluctuating airflows. In addition, the in situ experiments show that the largest drifting snow episodes appear during periods of roughly constant strong wind, whereas a short but strong blast does not produce significant drifting snow.  Key words. Drifting snow, blowing snow, gust, blast, acoustic sensor

EFFECT OF IMPROPER BALLAST PACKING/TAMPING ON DYNAMIC BEHAVIORS OF ON-TRACK RAILWAY CONCRETE SLEEPER

2007 ◽  
Vol 07 (01) ◽  
pp. 167-177 ◽  
Author(s):  
SAKDIRAT KAEWUNRUEN ◽  
ALEX M. REMENNIKOV
Keyword(s):  
Finite Element ◽  
Free Vibration ◽  
Dynamic Interaction ◽  
Two Dimensional ◽  
Shear Deformations ◽  
Dynamic Behaviors ◽  
Dimensional Finite Element ◽  
Parametric Studies ◽  
Nonlinear Distribution

Ballasted railway tracks are impaired due to either normal or abnormal operations. One of the problems is the differential settlements along the track. Clearly, there is the need to maintain periodically the track substructures by means of ballast packing/tamping. Inappropriate conducts result in the nonlinear distributions of support stiffness. This study firstly demonstrates the effects of improper ballast packing/tamping on the free vibration behaviors of in situ railway concrete sleepers. The two-dimensional finite element modeling of an in situ concrete sleeper was employed in the parametric studies. This model takes into account the coupled flexural-and-shear deformations of concrete sleepers, elastic displacements of fastening system, and nonlinear dynamic interaction between the sleeper and ballast support. Dynamic interaction between sleepers and ballast was investigated based on the nonlinear distribution of ballast support stiffness underneath the sleeper. Effects of both symmetrical and asymmetrical stiffness distributions on dynamic behaviors of the local in situ concrete sleeper were also highlighted.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

Sign in / Sign up

Export Citation Format

Share Document