scholarly journals Stress distributions and cell flows in a growing cell aggregate

2014 ◽  
Vol 4 (6) ◽  
pp. 20140033 ◽  
Author(s):  
Morgan Delarue ◽  
Jean-François Joanny ◽  
Frank Jülicher ◽  
Jacques Prost
Keyword(s):  
Cell Density ◽  
Cell Polarity ◽  
Local Stress ◽  
External Pressure ◽  
Experimental Results ◽  
Pressure Jump ◽  
Local Pressure ◽  
Active Stress ◽  
Growing Cell ◽  
Short Time

We discuss the short-time response of a multicellular spheroid to an external pressure jump. Our experiments show that 5 min after the pressure jump, the cell density increases in the centre of the spheroid but does not change appreciably close to the surface of the spheroid. This result can be explained if the cells are polarized which we show to be the case. Motivated by the experimental results, we develop a theory for polarized spheroids where the cell polarity is radial (except in a thin shell close to the spheroid surface). The theory takes into account the dependence of cell division and apoptosis rates on the local stress, the cell polarity and active stress generated by the cells and the dependence of active stress on the local pressure. We find a short-time increase of the cell density after a pressure jump that decays as a power law from the spheroid centre, which is in reasonable agreement with the experimental results. By comparing our theory to experiments, we can estimate the isotropic compression modulus of the tissue.

scholarly journals Simulation of the External Pressure Influence on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 247-252
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Suzana Gomes Fries ◽  
Ingo Steinbach ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Microstructural Evolution ◽  
Phase Field ◽  
Structural Evolution ◽  
Field Method ◽  
External Pressure ◽  
Experimental Results ◽  
Alloying Elements ◽  
Phase Field Method

The phase field method has been applied to simulate the microstructural evolution of a commercial single crystal Ni-based superalloy during both, HIP and annealing treatments. The effects of applying high isostatic pressure on the microstructural evolution, which mainly retards the diffusion of the alloying elements causing the loss of the orientational coherency between the phases is demonstrated by the simulation and experimental results

scholarly journals Fault Diagnosis of Rotating Machinery Based on One-Dimensional Deep Residual Shrinkage Network with a Wide Convolution Layer

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Jingli Yang ◽  
Tianyu Gao ◽  
Shouda Jiang ◽  
Shijie Li ◽  
Qing Tang
Keyword(s):  
Fault Diagnosis ◽  
Noise Immunity ◽  
Rotating Machinery ◽  
Experimental Results ◽  
Vibration Signals ◽  
One Dimensional ◽  
Noise Interference ◽  
Diagnosis Method ◽  
Diagnosis Model ◽  
Short Time

In actual engineering applications, inevitable noise seriously affects the accuracy of fault diagnosis for rotating machinery. To effectively identify the fault classes of rotating machinery under noise interference, an efficient fault diagnosis method without additional denoising procedures is proposed. First, a one-dimensional deep residual shrinkage network, which directly takes the raw vibration signals contaminated by noise as input, is developed to realize end-to-end fault diagnosis. Then, to further enhance the noise immunity of the diagnosis model, the first layer of the model is set to a wide convolution layer to extract short time features. Moreover, an adaptive batch normalization algorithm (AdaBN) is introduced into the diagnosis model to enhance the adaptability to noise. Experimental results illustrate that the fault diagnosis model for rotating machinery based on one-dimensional deep residual shrinkage network with a wide convolution layer (1D-WDRSN) can accurately identify the fault classes even under noise interference.

Effect of Creep Relaxation on the Delayed Hydride Cracking Behavior of Irradiated Zirconium 2.5%Wt Niobium Pressure Tube Material

2006 ◽  
Author(s):  
Heather Chaput ◽  
Brian W. Leitch ◽  
Don R. Metzger
Keyword(s):  
High Stress ◽  
Local Stress ◽  
Operating Conditions ◽  
Experimental Results ◽  
Pressure Tube ◽  
Experimental Program ◽  
Tube Material ◽  
Cracking Behavior ◽  
Delayed Hydride Cracking ◽  
Hydride Cracking

Surface scratches and flaws encountered in CANDU nuclear pressure tubes must be evaluated to ensure that a cracking mechanism, called delayed hydride cracking (DHC), is not initiated. The stress concentration due to a flaw can cause diffusion of hydrogen and precipitation of zirconium hydride at the flaw tip. The presence of a hydride results in reduced fracture resistance in a local region where high stress prevails. In many cases, flaws exist for an extended period of time before the hydrogen content in the base material is sufficient to form a hydride. In this situation high stress creep can significantly relax the local stress at the flaw tip. The assessment of flaws on the basis of local stress distribution not considering creep is expected to be overly conservative, and may result in unnecessary remedial action in reactor operation and maintenance procedures. An experimental program has been developed to isolate and quantify the effect of creep on DHC in irradiated Zr-2.5%Nb pressure tube material. As part of this program, the thermal and load histories relevant to reactor operating conditions have been considered, and initial experimental results indicate that the action of creep increases the threshold load for crack initiation. Finite element analysis of creep relaxation around a hydride also supports the experimental results, and a fracture initiation model is applied to the experimental conditions in order to establish an analytical trend for the effect of creep. The quantitative effect predicted by the model is in reasonable agreement with the experimental results, and an improved, less conservative assessment procedure that accounts for creep is deemed to be practical.

Buckling of Fibre-Reinforced Plastic-Steel Torispherical Shells Under External Pressure

1988 ◽  
Vol 202 (6) ◽  
pp. 409-420 ◽  
Author(s):  
G D Galletly ◽  
A Muc
Keyword(s):  
External Pressure ◽  
Experimental Results ◽  
Steel Shell ◽  
Elastic Buckling ◽  
Geometrical Parameters ◽  
Initial Shape ◽  
Buckling Modes ◽  
Reinforced Plastic ◽  
Composite Layers ◽  
Spherical Caps

The paper deals with the buckling of torispherical shells consisting of a steel external layer plus different numbers of composite layers. It is assumed that the total thickness of the fibre-reinforced plastic (FRP)-steel shell is constant but that the thickness of the steel and of the composite may be varied. In the paper it is shown (a) how the orientation of the fibres and the composite lamina thicknesses affect the elastic buckling modes and (b) how substantial increases in elastic buckling pressures may be achieved by reinforcing the steel torispheres with layers of composite. The analysis is carried out for various values of the geometrical parameters describing torispheres, including spherical caps. The influence of the yielding of the steel layer on the buckling pressures of FRP-steel torispheres is also discussed. As might be expected, it is necessary to take plasticity into account when predicting the buckling pressures of these shells. Some experimental results are given which confirm this expectation. The effect of initial shape imperfections in the shells is also considered briefly. However, the dearth of experimental results on FRP-steel shells prevents a proper evaluation of the way in which imperfections decrease their buckling strength.

The Effect of Pressure on the Bending Characteristics of an Actuator System

1960 ◽  
Vol 27 (3) ◽  
pp. 429-437 ◽  
Author(s):  
Paul Seide
Keyword(s):  
Fixed Point ◽  
Longitudinal Axis ◽  
External Pressure ◽  
Experimental Results ◽  
Point Location ◽  
Pivot Point ◽  
Effect Of Pressure ◽  
Actuator System

The effect of internal or external pressure on the bending of a cantilevered bellows, the movable end of which is permitted only to rotate about a fixed point on the longitudinal axis of the beam, is investigated. It is found that the bending characteristics of the system vary considerably with changes in pressure and pivot-point location and that instability of the system may occur. The experimental results given lend to confirm the behavior predicted by the theory.

The Quantitative Use of the Seinhorst ‘Mistifier’ to Recover Nematodes from Soil, Faeces and Herbage

1961 ◽  
Vol 35 (3-4) ◽  
pp. 309-314 ◽  
Author(s):  
R. F. Sturrock
Keyword(s):  
Experimental Results ◽  
High Rate ◽  
Rate Of Recovery ◽  
Short Time ◽  
Quantitative Recovery

A modified form of the Seinhorst “Mistifie.” is described which allows the quantitative recovery of nematodes from infested material. Experimental results are given showing the high rate of recovery in a short time, the recovery from a known number of nematodes and a not excessive degree of variation between recoveries from a replicated series of mistifier units. These results are discussed and the value of the technique for replicated quantitative work is stressed.

Comparison of Analytical and Experimental Results for Longitudinal Impacts on Elastic Rods

2003 ◽  
Vol 9 (1-2) ◽  
pp. 157-174 ◽  
Author(s):  
Bin Hu ◽  
Werner Schiehlen ◽  
Peter Eberhard
Keyword(s):  
Rigid Body ◽  
Elastic Vibration ◽  
Rigid Body Dynamics ◽  
Experimental Results ◽  
Hertzian Contact ◽  
Time Behavior ◽  
Elastic Rod ◽  
Hertzian Contact Law ◽  
Short Time

In this paper, the dynamic problem of a rigid body colliding with an elastic rod is studied in some detail. Different contact theories for modeling impact responses are compared with experimental measurements. Based on an idea originally presented by Sears for collisions of two rods with rounded ends, a boundary approach combining Hertzian contact law and St. Venant's elastodynamics is developed to describe longitudinal waves in rods. It is shown that this boundary approach agrees very well with experimental results. For the simulation of long-term dynamic behavior after impact, a traditional rigid-body approach is advantageous because the elastic vibration of the rod will decay fast due to the structural damping and the elastic rod then moves like a rigid body. Hence, for modeling longitudinal impacts, it is suggested that both elastodynamics and rigid-body dynamics are combined into a two-timescale model. The short time behavior of wave propagation due to impacts is modeled using elastodynamics, and the state of the rigid-body mode is transferred to the rigid-body approach as the initial condition for the motion. The long-term behavior after impact is then computed using the rigid-body approach.

scholarly journals Fermentation alcoolique : observations cinétiques

OENO One ◽  
1979 ◽  
Vol 13 (4) ◽  
pp. 281
Author(s):  
Pierre Strehaiano ◽  
Marc Moreno ◽  
Gérard Goma
Keyword(s):  
Ethanol Production ◽  
Cell Density ◽  
Alcoholic Fermentation ◽  
Initial Level ◽  
Cell Concentration ◽  
Experimental Results ◽  
Initial Concentration ◽  
Mise En Œuvre ◽  
Cette Observation ◽  
Nous Montrons

<p style="text-align: justify;">Dans un premier temps, les concepts cinétiques nécessaires à la compréhension et à la mise en œuvre de la fermentation alcoolique sont discutés.</p><p style="text-align: justify;">Dans un deuxième temps, à la lumière des résultats expérimentaux, nous montrons l'influence de la concentration initiale en sucre (glucose) sur les rendements en biomasse et en éthanol, sur la densité cellulaire et la vitesse moyenne de production d'éthanol. La concentration cellulaire est relativement faible (1,5 à 3 gl<sup>-1</sup>) et ce, quelle que soit la concentration initiale en substrat.</p><p style="text-align: justify;">Après avoir discuté cette observation, nous montrons qu'il n'existe pas de phase exponentielle de croissance et que, lorsque la concentration initiale en sucre augmente, la fraction de temps de fermentation qui s'effectue à un taux de croissance supérieur à 10<sup>-2</sup> µm diminue très sensiblement.</p><p style="text-align: justify;">+++</p><p style="text-align: justify;">In that work, kinetic concepts concerning understanding and process of alcoholic fermentation are discussed. Refering to experimental results, it is shown that yield of biomass and of ethanol, cell density and mean speed of ethanol production are in connection with the initial level of glucose. Cell concentration is relatively low without any correlation with the initial concentration of substrate.</p><p style="text-align: justify;">It is shown that exponential growing phase does not exist; when increases the initial level of glucose decreases strongly the time of fermentation occuring with a level growing higher than 10<sup>-2</sup> µm.</p>

Crack Position and Depth Identification in Rotating Shafts: Part 2 — Experimental Results

2005 ◽  
Author(s):  
Nicolo` Bachschmid ◽  
Paolo Pennacchi ◽  
Ezio Tanzi
Keyword(s):  
Dynamical Behavior ◽  
Industrial Applications ◽  
Experimental Results ◽  
Crack Identification ◽  
Identification Method ◽  
Different Types ◽  
Rotating Shafts ◽  
Short Time ◽  
Crack Position ◽  
Deep Crack

This paper presents the experimental validation of a model based transverse crack identification method suitable for industrial machines, described in part 1. The method is validated by experimental results obtained on two test rigs, which were expressly designed for investigating the dynamical behavior of cracked horizontal rotors. On the first test rig, only one crack type is considered, while on the second one three different types of crack have been analyzed: the first is a slot, therefore not actually a crack since it has not the typical breathing behavior, the second a small crack (14% of the diameter) and the third a deep crack (47% of the diameter). The excellent accuracy obtained in identifying position and depth of different cracks proves the effectiveness and reliability of the proposed method. Moreover, the implementation of identification method operates on a PC and takes short time to run, therefore is suitable for industrial applications.

Collapse Strength of Complex Metal Shell Intersections by the Effective Area Method

1998 ◽  
Vol 120 (3) ◽  
pp. 217-222 ◽  
Author(s):  
J. G. Teng
Keyword(s):  
Effective Area ◽  
External Pressure ◽  
Pressure Vessels ◽  
Metal Shell ◽  
Local Pressure ◽  
Area Method ◽  
Different Types ◽  
Bending Stresses ◽  
Slope Discontinuity ◽  
Shell Intersections

Cone-cone intersections and cone-cylinder intersections with or without ring stiffeners are common features in silos, tanks, pressure vessels, piping components, and other industrial shell structures. Under internal or external pressure, these intersections are subject to high circumferential membrane stresses as well as high bending stresses due to the presence of a slope discontinuity. As a result, they are susceptible to local plastic collapse. This paper first provides a summary of the effective area method initially proposed by Rotter for the plastic limit loads of cone-cylinder intersections in silos. The method is then generalized for complex intersections of cones and cylinders under uniform pressure and improved by including the local pressure effect. Results from the effective area method are compared with rigorous finite element results for a number of cases to demonstrate its accuracy. It is shown that the method is not only elegant and accurate, but also leads to a single simple formula for different types of intersections which is particularly suitable for codification purposes.

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