scholarly journals Allowable deviation of LC layer thickness in cholesteric LCDs

2002 ◽  
Vol 5 (1) ◽  
Author(s):  
A. Rybalochka ◽  
Keyword(s):  
Layer Thickness ◽  
Allowable Deviation

Tolerance-Based Layer Setup Optimization for Layered Manufacturing

2010 ◽  
Author(s):  
Jack Szu-Shen Chen ◽  
Hsi-Yung Steve Feng
Keyword(s):  
Layer Thickness ◽  
Maximum Error ◽  
Layered Manufacturing ◽  
Design Model ◽  
Maximum Efficiency ◽  
Original Design ◽  
Allowable Deviation ◽  
Number Of Layers ◽  
Build Time ◽  
Model Geometry

This paper introduces a new tolerance-based method to generate the optimum layer setup required to build layered manufacturing (LM) end-user parts for maximized efficiency. To achieve this, the deviation between the final polished LM part geometry and the original design model are formulated and controlled. Maximized layer thicknesses are then realized through optimization of each layer position with respect to the design and final geometry and maximization of the allowable deviation for each layer, which consequently leads to minimization of the build time. Current LM layer setup methods do not take into account of the final part during layer setup generation, rendering layer thickness selection to operator-deemed-best. Without the ability to predict the final geometry and to optimize the layer setup accordingly, layer thickness selection is often overly conservative, causing more layers than necessary to be used. Since the LM build time increases exponentially with an increase in the number of layers, efficiency is greatly reduced with conservative layer setup. To achieve maximum efficiency, this paper proposes a new method based on error compensation and minimization to solve for the optimum layer setup necessary to allow the resulting final physical part to reliably approximate the design model geometry according to a user specified tolerance limit. Case studies have been performed in order to validate that the proposed method is able to minimize the number of layers for constructing an LM part while controlling the maximum error for tolerance conformance.

Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

1991 ◽  
Vol 49 ◽  
pp. 900-901 ◽  
Author(s):  
Alain Claverie ◽  
Zuzanna Liliental-Weber
Keyword(s):  
Transport Properties ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Lattice Parameter ◽  
Crystalline Quality ◽  
Insulating Properties ◽  
Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

On the Effect of 2-Layer Thickness by High-Specific Gravity Armor Blocks on Wave Reflection

1999 ◽  
Author(s):  
Masahiro Ito ◽  
Yuitch Iwagaki ◽  
Hiroshi Murakami ◽  
Kenji Nemoto ◽  
Masato Yamamoto ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Layer Thickness ◽  
Wave Reflection ◽  
High Specific Gravity

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

Making Graphene-type Material via Polymerization of Porphyrin

2020 ◽  
Author(s):  
SANJIB KAR ◽  
Sruti Mondal ◽  
Kasturi Sahu ◽  
Dilruba Hasina ◽  
Tapobrata Som ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Polymeric Material ◽  
Single Layer ◽  
Type Material ◽  
Synthetic Pathway ◽  
Simple Chemical ◽  
Doped Graphene ◽  
Ring Nitrogen ◽  
2D Structure ◽  
Porphyrin Macrocycles

<p>The synthesis of new graphene-type materials (<i>via</i> polymerization of porphyrin macrocycles) through a simple chemical synthetic pathway (at RT) has been demonstrated. This newly synthesized material can be dispersed in water with an average sheet size of few microns and with single layer thickness. As the porphyrin contains four inner ring nitrogen atoms thus the presented polymeric material will be close analogous of N-doped graphene. Porphyrin as the key component to synthesize layered graphene type continuous 2D structure has never been attempted before. </p> <p> </p>

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