Rectilinear low-frequency shear of homogeneously aligned nematic liquid crystals

1993 ◽  
Vol 441 (1913) ◽  
pp. 559-573 ◽  
Keyword(s):  
Thin Film ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Theoretical Analysis ◽  
Low Frequency ◽  
The Other ◽  
Critical Amplitude ◽  
Linear Shear ◽  
Theoretical Results ◽  
Good Agreement

A thin film of nematic liquid crystal (ZLI 1085) is sandwiched between two horizontally mounted glass blocks, whose faces have been treated to align the molecules of the liquid parallel to the plane of the blocks. By moving one block relative to the other in its own plane, the liquid crystal is subjected to an oscillatory linear shear. Above a certain frequency-dependent amplitude, mechanical Williams domains of alternating bright and dark stripes are observed perpendicular to the direction of shear. A theoretical analysis of this phenomenon is carried out to provide predictions for both the thickness of the stripes and the critical amplitude as a function of frequency. Good agreement is found between the experimental and theoretical results.

scholarly journals Optical Kossel Lines and Fluorescence in Photonic Liquid Crystals

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 541
Author(s):  
Vladimir A. Belyakov
Keyword(s):  
Experimental Data ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Light Absorption ◽  
Fluorescence Polarization ◽  
Direct Connection ◽  
X Ray ◽  
Optical Analog ◽  
Theoretical Results ◽  
Observation Results

We propose a general analytical way to describe the fluorescence peculiarities in photonic liquid crystals (revealing themselves as an optical analog of the X-ray Kossel lines in conventional crystals) based at the localized optical edge modes existing in perfect photonic liquid crystal layers. The proposed approach allows us to predict theoretically the properties of optical Kossel lines in photonic liquid crystal (fluorescence polarization, spectral and angular fluorescence distribution, influence of the light absorption in liquid crystal, and, in particular, existing the optical Borrmann effect if the absorption in liquid crystal is locally anisotropic). Comparison of the theoretical results and the known experimental data shows that the theory reproduces sufficiently well the observation results on the fluorescence in photonic liquid crystals. For confirming a direct connection of the optical Kossel lines to the localized optical edge modes in perfect photonic liquid crystal, we propose the application of time-delayed techniques in studying the optical Kossel lines.

Pattern Formation During the Growth of Liquid Crystal Phases

MRS Bulletin ◽  
1991 ◽  
Vol 16 (1) ◽  
pp. 38-45 ◽  
Author(s):  
Patrick Oswald ◽  
John Bechhoefer ◽  
Francisco Melo
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Unit Vector ◽  
The Other ◽  
Two Dimensional ◽  
Smectic A ◽  
Anisotropic Plastic ◽  
Fundamental Research ◽  
Crystal Phases ◽  
Columnar Mesophases

Liquid crystals, discovered just a century ago, have wide application to electrooptic displays and thermography. Their physical properties have also made them fascinating materials for more fundamental research.The name “liquid crystals” is actually a misnomer for what are more properly termed “mesophases,” that is, phases having symmetries intermediate between ordinary solids and liquids. There are three major classes of liquid crystals: nematics, smectics, and columnar mesophases. In nematics, although there is no correlation between positions of the rodlike molecules, the molecules tend to lie parallel along a common axis, labeled by a unit vector (or director) n. Smectics are more ordered. The molecules are also rodlike and are in layers. Different subtypes of smectics (labeled, for historical reasons, smectic A, smectic B,…) have layers that are more or less organized. In the smectic A phase, the layers are fluid and can glide easily over each other. In the smectic B phase, the layers have hexagonal ordering and strong interlayer corrélations. Indeed, the smectic B phase is more a highly anisotropic plastic crystal than it is a liquid crystal. Finally, columnar mesophases are obtained with disklike molecules. These molecules can stack up in columns which are themselves organized in a two-dimensional array. There is no positional correlation between molecules in one column and molecules in the other columns.

scholarly journals A bistable structural element

2008 ◽  
Vol 222 (11) ◽  
pp. 2045-2051 ◽  
Author(s):  
T Schioler ◽  
S Pellegrino
Keyword(s):  
Theoretical Analysis ◽  
Analytical Model ◽  
Mechanical Behaviour ◽  
The Other ◽  
Experimental Measurements ◽  
Structural Element ◽  
High Stiffness ◽  
Revolute Joints ◽  
Prototype Structure ◽  
Good Agreement

This article presents a novel bistable structural element that has high stiffness in stable configurations, but requires only a small amount of energy to be switched from one configuration to the other. The element is based on a planar linkage of four bars connected by revolute joints, braced by tape-spring diagonals. A description of the concept is presented, along with a detailed theoretical analysis of its mechanical behaviour. Experimental measurements obtained from a prototype structure are found to be in very good agreement with the predictions from this analytical model.

Tunable properties of light propagation in photonic liquid crystal fibers

2006 ◽  
Vol 14 (4) ◽  
Author(s):  
K. Szaniawska ◽  
T. Nasilowski ◽  
T. Woliński ◽  
H. Thienpont
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Light Propagation ◽  
Solid Core ◽  
Simulation Methods ◽  
Pure Silica ◽  
Tunable Properties ◽  
Crystal Fibers ◽  
Propagation Properties ◽  
Good Agreement

AbstractTunable properties of light propagation in photonic crystal fibers filled with liquid crystals, called photonic liquid crystal fibers (PLCFs) are presented. The propagation properties of PLCFs strongly depend on contrast between refractive indices of the solid core (pure silica glass) and liquid crystals (LCs) filing the holes of the fiber. Due to relatively strong thermo-optical effect, we can change the refractive index of the LC by changing its temperature. Numerical analysis of light propagation in PLCF, based on two simulation methods, such as finite difference (FD) and multipole method (MM) is presented. The numerical results obtained are in good agreement with our earlier experimental results presented elsewhere [1].

The Separation of Light Gaseous Isotopes by Mass Diffusion Columns II

1964 ◽  
Vol 19 (6) ◽  
pp. 747-755
Author(s):  
W. J. De Wet ◽  
J. Los
Keyword(s):  
Theoretical Analysis ◽  
Mass Diffusion ◽  
Experimental Results ◽  
The Other ◽  
Countercurrent Flow ◽  
Gas Solubility ◽  
Flow Rates ◽  
Mixing Effects ◽  
Other Hand ◽  
Good Agreement

The design of mass diffusion columns operated with partition membranes, for the separation of light gaseous isotopes, is discussed. A theoretical analysis of experimental results obtained indicates that a good agreement between experimental results and theory is only obtained at low column pressures and moderate countercurrent flow rates. At fairly low countercurrent flow rates mixing effects due to viscous dragging and gas solubility by the condensate appear to be considerable whereas excessively high countercurrent flow rates, on the other hand, also seem undesirable. Some suggestions are proposed to obviate impairing effects at least to some extent.

Analysis of Ship End Launching Without Fore Poppet

1996 ◽  
Vol 12 (03) ◽  
pp. 172-177
Author(s):  
Wei Qin Shen
Keyword(s):  
Theoretical Analysis ◽  
Computer Program ◽  
New Technology ◽  
Ritz Method ◽  
Measured Data ◽  
Bending Moments ◽  
Optimum Arrangement ◽  
Longitudinal Bending ◽  
Theoretical Results ◽  
Good Agreement

A new technology on the end launching of a ship without fore poppet is presented. A theoretical analysis of the new technology is carried out based on the actual measurements which were recorded during the launching. By means of the Ritz method, the reactive forces from launching ways, the deflection curves and the longitudinal bending moments of ship hull beams are calculated for two ships under three assumptions. The theoretical results are in good agreement with the measured data. The strength of ships in the launching process is examined. A computer program for an optimum arrangement of the blocks is proposed.

Estimation of the heat capacity of CdTe semiconductor

2016 ◽  
Vol 30 (04) ◽  
pp. 1650026 ◽  
Author(s):  
Hüseyin Koç ◽  
Erhan Eser
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Binomial Coefficient ◽  
Debye Model ◽  
The Other ◽  
Temperature Range ◽  
Theoretical Results ◽  
Good Agreement

The aim of this paper is to provide a simple and reliable analytical expression for the thermodynamic properties calculated in terms of the Debye model using the binomial coefficient, and examine specific heat capacity of CdTe in the 300–1400 K temperature range. The obtained results have been compared with the corresponding experimental and theoretical results. The calculated results are in good agreement with the other results over the entire temperature range.

Alternative Complex Liquid Crystal Displays

1989 ◽  
Vol 149 ◽  
Author(s):  
E P Raynes
Keyword(s):  
Thin Film ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Liquid Crystal Displays ◽  
Ferroelectric Liquid Crystals ◽  
Alternative Technologies ◽  
Complex Liquid ◽  
Major Progress

ABSTRACTThe first major progress towards complex LCD's has been made using arrays of thin film transistors (TFT's) fabricated using amorphous silicon (a - Si) technology. However, apart from other two and three terminal devices, there are also two new LCD technologies which directly improve the performance of the LCD without the need for extra switching elements. These are the supertwist (or STN) LCD and displays based on ferroelectric liquid crystals (FELC). These two alternative technologies are described and teir performance compared with that of displays fabricated using α - Si TFT's.

scholarly journals Ion-Generating and Ion-Capturing Nanomaterials in Liquid Crystals

Proceedings ◽  
2018 ◽  
Vol 2 (14) ◽  
pp. 1122
Author(s):  
Yuriy Garbovskiy
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Fields ◽  
Future Research ◽  
Research Directions ◽  
Liquid Crystal Devices ◽  
Proposed Model ◽  
Future Research Directions ◽  
Practical Implications ◽  
Good Agreement

The majority of tunable liquid crystal devices are driven by electric fields. The performance of such devices can be altered by the presence of small amounts of ions in liquid crystals. Therefore, the understanding of possible sources of ions in liquid crystal materials is very critical to a broad range of existing and future applications employing liquid crystals. Recently, nanomaterials in liquid crystals have emerged as a hot research topic, promising for its implementation in the design of wearable and tunable liquid crystal devices. An analysis of published results revealed that nanodopants in liquid crystals can act as either ion-capturing agents or ion-generating objects. In this presentation, a recently developed model of contaminated nanomaterials is analyzed. Nanoparticle-enabled ion capturing and ion generation regimes in liquid crystals are discussed within the framework of the proposed model. This model is in very good agreement with existing experimental results. Practical implications and future research directions are also discussed.

scholarly journals Theoretical Analysis of the Influence of Asperity’s Dimensions Affected by a Scale Factor on the Mixed Lubrication between Parallel Surfaces

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
F. Robbe-Valloire ◽  
R. Progri ◽  
T. Da Silva Botelho
Keyword(s):  
Theoretical Analysis ◽  
Boundary Lubrication ◽  
Scaling Factor ◽  
Mixed Lubrication ◽  
Local Boundary ◽  
Mixed Regime ◽  
Parallel Surfaces ◽  
Speed Parameter ◽  
Theoretical Results ◽  
Good Agreement

Mixed lubrication between a given pair of surfaces is directly related to the parameter ηu/p. Any change in microgeometry produces a shift in the transition between the boundary and lubricated regimes. Using an asperity based model including five families of asperities (2 for full fluid lubrication and 3 for local boundary lubrication), we simulate mixed lubricated behavior. Our theoretical results confirm the relation between the mixed regime and the ηu/p parameter. All homothetic changes in microgeometry affecting the vertical and horizontal directions by the same scaling factor Sc induce a shift in the transition. The most interesting result is that this shift is exactly the same if speed u is scaled by 1/Sc with the initial microgeometry. This particular behavior, which is in good agreement with experimental results proposed in the literature, comes from the fact that behavior at each asperity can be written using dimensionless parameters. Most of these parameters are independent to any scaling of the microgeometry and only one, the speed parameter, needs to be artificially scaled in order to remain unchanged by the modification of the microgeometry.

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