Soft cluster-induced desorption and ionization of biomolecules—Influence of surface load and morphology on desorption efficiency

2011 ◽  
Vol 99 (23) ◽  
pp. 234103 ◽  
Author(s):  
M. Baur ◽  
B.-J. Lee ◽  
C. R. Gebhardt ◽  
M. Dürr
Keyword(s):  
Surface Load ◽  
Desorption Efficiency ◽  
Soft Cluster

MODELING OF THE STRESS-STRAIN STATE OF A TRANSPORT TUNNEL UNDER LOAD AS A MEASURE TO REDUCE OPERATIONAL RISKS TO TRANSPORTATION FACILITIES

2020 ◽  
Vol 3 (8) ◽  
pp. 28-34
Author(s):  
N. V. IVANITSKAYA ◽  
◽  
A. K. BAYBULOV ◽  
M. V. SAFRONCHUK ◽  
◽  
...  
Keyword(s):  
Strain State ◽  
Moving Load ◽  
Element Model ◽  
Transport Infrastructure ◽  
Design Stage ◽  
Surface Load ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operational Risks ◽  
Von Mises

In many countries economic policy has been paying increasing attention to the modernization and development of transport infrastructure as a measure of macroeconomic stimulation. Tunnels as an important component of transport infrastructure save a lot of logistical costs. It stimulates increasing freight and passenger traffic as well as the risks of the consequences of unforeseen overloads. The objective of the paper is to suggest the way to reduce operational risks of unforeseen moving load by modeling of the stress-strain state of a transport tunnel under growing load for different conditions and geophysical parameters. The article presents the results of a study of the stress-strain state (SSS) of a transport tunnel exposed to a mobile surface load. Numerical experiments carried out in the ANSYS software package made it possible to obtain diagrams showing the distribution of equivalent stresses (von Mises – stresses) according to the finite element model of the tunnel. The research results give grounds to assert that from external factors the stress state of the tunnel is mainly influenced by the distance to the moving load. The results obtained make it possible to predict in advance the parameters of the stress-strain state in the near-contour area of the tunnel and use the results in the subsequent design of underground facilities, as well as to increase their reliability and operational safety. This investigation gives an opportunity not only to reduce operational risks at the design stage, but to choose an optimal balance between investigation costs and benefits of safety usage period prolongation.

The Numerical Analysis of the Velocity and Pressure Distribution of the Oil Film in Heavy Hydrostatic Thrust Bearing

2014 ◽  
Vol 541-542 ◽  
pp. 658-662
Author(s):  
Jian Li ◽  
Yuan Chen ◽  
Yang Chun Yu ◽  
Zhu Xin Tian ◽  
Yu Huang
Keyword(s):  
Mathematical Model ◽  
Numerical Analysis ◽  
Pressure Distribution ◽  
Working Conditions ◽  
Thrust Bearing ◽  
Rotation Speed ◽  
The Other ◽  
Surface Load ◽  
Oil Film ◽  
Volume Method

To study the velocity and pressure distribution of the oil film in a heavy hydrostatic thrust bearing, a mathematical model of the velocity is proposed and the finite volume method (FVM) has been used to simulate the flow field under different working conditions. Some pressure experiments were carried out and the results verified the correctness of the simulation. It is concluded that the pressure distribution varies small under different rotation speed when the surface load on the workbench is constant. But the velocity of the oil film is influenced greatly by the rotation speed. When the rotation speed of the workbench is as quick as enough, the velocity of the oil film on one radial side of the pad will be zero, that is to say the lubrication oil will be drained from the other three sides of the recess.

On the Natural Lubrication of Synovial Joints: Normal and Degenerate

1977 ◽  
Vol 99 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Joseph M. Mansour ◽  
Van C. Mow
Keyword(s):  
Articular Cartilage ◽  
Solid Phase ◽  
Articular Surface ◽  
Moving Load ◽  
Frictional Resistance ◽  
Elastic Solid ◽  
Surface Load ◽  
Two Phase ◽  
Tissue Properties ◽  
Synovial Joints

Fluid flow and mass transport mechanisms associated with articular cartilage function are important biomechanical processes of normal and pathological synovial joints. A three-layer permeable, two-phase medium of an incompressible fluid and a linear elastic solid are used to model the flow and deformational behavior of articular cartilage. The frictional resistance of the relative motion of the fluid phase with respect to the solid phase is given by a linear diffusive dissipation term. The subchondral bony substrate is represented by an elastic solid. The three-layer model of articular cartilage is chosen because of the known histological, ultrastructural, and biomechanical variations of the tissue properties. The calculated flow field shows that for material properties of normal healthy articular cartilage the tissue creates a naturally lubricated surface. The movement of the interstitial fluid at the surface is circulatory in manner, being exuded in front and near the leading half of the moving surface load and imbibed behind and near the trailing half of the moving load. The flow fields of healthy tissues are capable of sustaining a film of fluid at the articular surface whereas pathological tissues cannot.

Manufacturing and Characterization of Nanostructures Using Scanning Tunneling Microscopy with Diamond Tip

2016 ◽  
Vol 42 ◽  
pp. 14-46 ◽  
Author(s):  
Oleg G. Lysenko ◽  
Vladimir I. Grushko ◽  
Sergey N. Dub ◽  
Eugene I. Mitskevich ◽  
Nikolay V. Novikov ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Measuring System ◽  
Scanning Tunneling ◽  
Surface Load ◽  
Tunneling Microscopy ◽  
Electromagnetic Probe ◽  
High Pressure High Temperature ◽  
Single Crystal Diamond ◽  
Selection Of

Nanoscale experiments with diamond tip that include processing, visualization and tunneling spectroscopy of the surface are presented. Single crystal diamond synthesized by the temperature gradient method under high pressure–high temperature (HPHT) conditions is proposed as a multifunctional tip for scanning tunneling microscopy (STM). Sequence of the procedures covering growing crystals with predetermined physical properties, selection of the synthesized crystals with the desired habit and their precise shaping have been developed. The original STM’s peculiarity is the electromagnetic probe-to-surface load measuring system. The results of fabrication and characterization of nanostructures for nanoelectronics, data storages and biology are demonstrated and discussed.

Assessment of AASHTO Load-Spreading Method for Buried Culverts and Proposed Improvement

2021 ◽  
pp. 036119812110215
Author(s):  
Michael G. Katona
Keyword(s):  
Ad Hoc ◽  
Soil Depth ◽  
Free Field ◽  
Peak Stress ◽  
Element Model ◽  
Surface Load ◽  
Accuracy Evaluation ◽  
Simple Modification ◽  
Homogeneous Half Space ◽  
Order Of Magnitude

AASHTO’s ad hoc method (AAM) for predicting free-field soil stress under a rectangular loading area is a simple and very useful tool for the analysis of buried culverts subject to vehicular wheel loads. AAM assumes the surface load spreads with soil depth into an ever-increasing rectangular area whose dimensions are controlled by a constant spread angle θ usually taken as 30°, denoted as AAM-30°. Both simplified and comprehensive culvert analysis procedures utilize AAM predictions for adjusting pressure distributions acting on the culvert periphery. Also, AAM-30° is routinely used to determine the two-wheel soil interaction depth, in which the combined effect of both axial wheels need to be considered. To date, a thorough accuracy analysis of AAM-30° has not been published in the open literature. This paper provides a unique and rigorous evaluation of AAM-30° using an exact solution from an elasticity-based model (EBM) of a homogeneous half-space with rectangular surface load. One key discovery is the depth parameter called y*, which is the soil depth at which AAM-30° peak-stress prediction exactly matches the exact EBM solution. Moreover, it is shown that y* may be determined by a simple, yet accurate formula that only depends on the square root of the load area. However, the investigation reveals that AAM-30° significantly underestimates peak stress in the shallow-depth zone 0 <  y < ½ y* by as much as 31.3% of the applied surface pressure. As this is a large nonconservative error it cannot be ignored. Accordingly, a very simple modification is introduced called AAM-θ*, in which θ* is a spread angle that linearly increases to 30° at soil depth ½ y* and thereafter θ* remains constant at 30°. An accuracy evaluation of AAM-θ* reveals an order of magnitude increase in accuracy in which the small residual error is conservative, not nonconservative. The paper concludes with discussions on applying AAM-θ* to the analysis of buried culverts when using either simple or finite element model solution procedures.

Lithosphere flexure estimation of an non-uniform flexural rigidity plate：A quantitative modeling approach

2021 ◽  
Author(s):  
Mingju Xu ◽  
Zhaocai Wu ◽  
Fei Ji ◽  
Aiguo Ruan ◽  
Chunfeng Li
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Flexural Rigidity ◽  
Density Contrast ◽  
Surface Load ◽  
Model Errors ◽  
Mantle Material ◽  
Partial Differential ◽  
Estimation Errors ◽  
Tectonic Plates

&lt;p&gt;Lithosphere motion is one of the fundamental processes in Earth tectonics. To understand the processes involving the nature of tectonic evolution and dynamics, it is critical to figure out the lithosphere flexure of tectonic plates. Over long-term (&gt; 10&lt;sup&gt;5&lt;/sup&gt;&amp;#160;yr) geological timescales, the lithosphere can be modelled as flexing like a thin,&amp;#160;elastic plate, using the partial differential equation for flexure of an orthotropic plate. The partial differential equation is used indirectly to form theoretical admittance and coherence curves, which are then compared against the observed admittance and coherence to invert a non-uniform flexural rigidity (or effective elastic thickness, &lt;em&gt;T&lt;sub&gt;e&lt;/sub&gt;&lt;/em&gt;) plate. The non-uniform flexural rigidity lithosphere flexure amplitude can be estimated after that.&lt;/p&gt;&lt;p&gt;In this presentation, we use the classic lithosphere model with applied surface load at ground and internal load at Moho,&amp;#160;but assume that the compensation material is denser than the mantle material beneath Moho. The density contrast between compensation material and mantle material beneath Moho is set to be 200 kg/m&lt;sup&gt;3&lt;/sup&gt;&amp;#160;referring to the density contrast of the uppermost and bottom lithosphere mantle. In such a lithosphere model, errors of lithosphere flexure estimation are mainly&amp;#160;contributed by&amp;#160;the errors of&lt;em&gt; T&lt;sub&gt;e&lt;/sub&gt;&amp;#160;&lt;/em&gt;and Moho recovering.&amp;#160;Synthetic modelling is then performed to analyze the incoming influence deriving from&lt;em&gt; T&lt;sub&gt;e&lt;/sub&gt;&lt;/em&gt;&amp;#160;and Moho errors.&lt;/p&gt;&lt;p&gt;The synthetic modelling reflects 1) the lithosphere flexure estimation errors are not sensitive to the errors of &lt;em&gt;T&lt;sub&gt;e &lt;/sub&gt;&lt;/em&gt;recovering, even an error of about 10 km of &lt;em&gt;T&lt;sub&gt;e &lt;/sub&gt;&lt;/em&gt;only result in an error within 1km of lithosphere flexure, 2) the influence of Moho errors to lithosphere flexure errors will be magnified in regions where &lt;em&gt;T&lt;sub&gt;e&lt;/sub&gt;&amp;#160;&lt;/em&gt;is low, as lithosphere flexure errors over 1km mainly occur in regions where &lt;em&gt;T&lt;sub&gt;e&lt;/sub&gt;&lt;/em&gt;&amp;#160;is lower than 8km.&lt;/p&gt;

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