BEM-based second-order imperfect interface modeling of potential problems with thin layers

2021 ◽  
pp. 111155
Author(s):  
Zhilin Han ◽  
Sofia G. Mogilevskaya ◽  
Svetlana Baranova ◽  
Dominik Schillinger
Keyword(s):  
Imperfect Interface ◽  
Second Order ◽  
Thin Layers ◽  
Interface Modeling ◽  
Potential Problems

Surface Finite Element for Imperfect Interface Modeling in Elastic Properties Homogenization

2020 ◽  
Vol 833 ◽  
pp. 101-106
Author(s):  
Alexander Pavlovich Sokolov ◽  
Vitaliy Nikolaevich Schetinin ◽  
Mikhail Yurievich Kozlov
Keyword(s):  
Finite Element ◽  
Elastic Properties ◽  
Numerical Experiments ◽  
Averaging Method ◽  
Jump Condition ◽  
Imperfect Interface ◽  
Adhesion Layer ◽  
Interface Modeling ◽  
Asymptotic Averaging

The paper presents a mathematical model of a finite element for modeling imperfect interface conditions for two contacting surfaces. The element is used in the numerical implementation of the Asymptotic Averaging Method (AAM) for the determination of effective elastic properties of composite materials under investigation. Numerical experiments are carried out to calculate the elastic properties taking into account the adhesion layer using a displacements field jump condition at the phase boundary. Results are compared with adhesion modeling using an additional bulk phase.

Creation of a second-order nonlinear susceptibility in As2S3 chalcogenide glass thin layers.

2000 ◽  
Author(s):  
Y. Quiquempois ◽  
A. Villeneuve ◽  
D. Dam ◽  
K. Turcotte ◽  
J. Maier ◽  
...  
Keyword(s):  
Chalcogenide Glass ◽  
Second Order ◽  
Thin Layers ◽  
Nonlinear Susceptibility

MIRRORLESS OPTICAL PARAMETRIC OSCILLATORS

1996 ◽  
Vol 05 (02) ◽  
pp. 223-246 ◽  
Author(s):  
YUJIE J. DING ◽  
JACOB B. KHURGIN
Keyword(s):  
Pump Power ◽  
Incident Angle ◽  
Growth Direction ◽  
Second Order ◽  
Thin Layers ◽  
Optical Parametric Oscillators ◽  
Parametric Oscillators ◽  
Domain Structures ◽  
Optical Parametric ◽  
Asymmetric Quantum

We have considered two novel configurations for optical parametric oscillators (OPO’s): transversely-pumped counter-propagating and nondegenerate backward OPO’s due to the distributed feedback provided through the opposite propagation directions of the signal and idler. In both configurations, by changing the incident angle of the pump beam, one can tune the output frequency in a large range. The threshold pump powers for the oscillation can be as low as ~10 W for the transversely-pumped counter-propagating OPO’s and 44 W for the nondegenerate backward OPO’s. The quasi-phase matching is achieved by spatially modulating second-order susceptibility along the growth direction based on semiconductor alternating thin layers or asymmetric quantum-well domain structures or by electric-field poling in conventional second-order nonlinear materials. The nondegenerate backward OPO’s offer the most efficient conversion among all the configurations for the OPO’s having the same threshold pump power. The transversely-pumped counter-propagating OPO’s have the optimal pump power.

scholarly journals Extending the Numerical Stability Limit of Terrain-Following Coordinate Models over Steep Slopes

2012 ◽  
Vol 140 (11) ◽  
pp. 3722-3733 ◽  
Author(s):  
Günther Zängl
Keyword(s):  
Pressure Gradient ◽  
Numerical Stability ◽  
Stability Limit ◽  
Second Order ◽  
Thin Layers ◽  
Horizontal Pressure Gradient ◽  
Wide Range ◽  
Terrain Following ◽  
Horizontal Pressure ◽  
Steep Slopes

Abstract To extend the numerical stability limit over steep slopes, a truly horizontal pressure-gradient discretization based on the ideas formulated by Mahrer in the 1980s has been developed. Conventionally, the pressure gradient is evaluated in the terrain-following coordinate system, which necessitates a metric correction term that is prone to numerical instability if the height difference between adjacent grid points is much larger than the vertical layer spacing. The alternative way pursued here is to reconstruct the pressure gradient at auxiliary points lying at the same height as the target point on which the velocity is defined. This is accomplished via a second-order Taylor-series expansion in this work, using the hydrostatic approximation to transform the second derivatives into first derivatives to facilitate second-order accurate discretization in the presence of strong vertical grid stretching. Moreover, a reformulated lower boundary condition is used that avoids the extrapolation of vertical derivatives evaluated in potentially very thin layers. A sequence of tests at varying degrees of idealization reveals that the truly horizontal pressure-gradient discretization improves numerical stability over steep slopes for a wide range of horizontal mesh sizes, ranging from a few hundreds of meters to tens of kilometers. In addition, tests initialized with an atmosphere at rest reveal that the spurious circulations developing over steep mountains are usually smaller than for the conventional discretization even in configurations for which the latter does not suffer from stability problems.

Higher-order imperfect interface modeling via complex variables based asymptotic analysis

2020 ◽  
Vol 157 ◽  
pp. 103399 ◽  
Author(s):  
S. Baranova ◽  
S.G. Mogilevskaya ◽  
T.H. Nguyen ◽  
D. Schillinger
Keyword(s):  
Asymptotic Analysis ◽  
Imperfect Interface ◽  
Higher Order ◽  
Complex Variables ◽  
Interface Modeling

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

Microbulldozing and Microchiseling

1969 ◽  
Vol 27 ◽  
pp. 134-135
Author(s):  
J.N. Ramsey ◽  
D.P. Cameron ◽  
F.W. Schneider
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Material Handling ◽  
Microprobe Analysis ◽  
Foreign Matter ◽  
Specific Location ◽  
Potential Problems ◽  
Knoop Indenter ◽  
Scanning Electron ◽  
Microhardness Tester

As computer components become smaller the analytical methods used to examine them and the material handling techniques must become more sensitive, and more sophisticated. We have used microbulldozing and microchiseling in conjunction with scanning electron microscopy, replica electron microscopy, and microprobe analysis for studying actual and potential problems with developmental and pilot line devices. Foreign matter, corrosion, etc, in specific locations are mechanically loosened from their substrates and removed by “extraction replication,” and examined in the appropriate instrument. The mechanical loosening is done in a controlled manner by using a microhardness tester—we use the attachment designed for our Reichert metallograph. The working tool is a pyramid shaped diamond (a Knoop indenter) which can be pushed into the specimen with a controlled pressure and in a specific location.

EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries

1996 ◽  
Vol 54 ◽  
pp. 342-343
Author(s):  
S.J. Splinter ◽  
J. Bruley ◽  
P.E. Batson ◽  
D.A. Smith ◽  
R. Rosenberg
Keyword(s):  
Electronic Structure ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Thin Layers ◽  
Nominal Composition ◽  
Spatially Resolved ◽  
Service Lifetime ◽  
Heat Treated ◽  
Probe Size ◽  
Local Electronic Structure

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

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