Multilayer Theory Research Articles

Exploration of the sum of flexoelectric coefficients of nematic liquid crystals

We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry, which comprises pyramid, matching fluid, and strongly anchored hybrid-aligned nematic liquid crystal (NLC) cell on the internal angle. The calculation is based on the multi-layer optical theory and the elastic theory of liquid crystals. For different sums of flexoelectric coefficients e11 and e33, the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients. Consequently, the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.

Comparison of Design Thicknesses for Flexible Airfield Pavement Based on Agency Limiting Subgrade Strain Criteria

A newly developed mechanistically based design procedure for airfield hot-mix asphalt pavement is studied. The pavement performance is calculated in terms of critical strains on the basis of multilayer theory. Rutting failure criteria from the Asphalt Institute, Shell Oil, and the revised U.S. Army Engineer Waterways Experiment Station (USACE-WES) are used to calculate the thickness requirements necessary for a range of design input variables. The program has been implemented in ZAPRAM, an event-driven, user-friendly educational computer program that runs in the Excel 2007 environment, coupled with Visual Basic programming. Results of the design comparison indicate a significant difference between the three common airfield pavement design procedures used. Differences between the Asphalt Institute procedure and the revised USACE-WES procedure are relatively moderate for all design situations. The greatest deviation is found between the Shell Oil approach and the other two criteria. The design difference depends heavily on several major factors. An analysis of heavy aircraft (B-747) operating on a low-support subgrade foundation may yield pavement design differences of 2 to 3 ft of granular subbase material. A major effort to enhance the state of the art for airfield pavement design models is recommended.

Simulation of Ultrashort Pulse Shaping Filter Based on Multilayer Volume Holographic Gratings

Shaping and filtering of ultrashort pulsed beam at 1.06um by using multilayer volume holographic gratings (MVHGs) is analyzed. The modified multilayer coupled wave theory used to analyze the Bragg diffraction of a system of MVHG is derived. The spectral intensity distributions of the diffracted beam are calculated. The diffraction bandwidth, diffraction pulse duration and the total diffraction efficiency of the filter are also analyzed. Control of the optical pulse shape is accomplished by adjusting the width of the intermediate layer of an optical filter of MVHGs. This pulse shaping technique will be useful in the optical communication and optical computing systems.

Determination of Director Profile in the Vertical Alignment Nematic Liquid Crystal Cell by the Full Leaky Guided Mode Technique

By means of the full leaky guided mode technique, the transmittance of the full leaky waveguide geometry which consists of pyramid, matching fluid of refractivity, the vertical alignment nematic liquid crystal cell are investigated experimentally. The experimental curves with different voltages between polarization-conserving transmittance Tss and the internal angle (the angle of incidence for which light is incident on the vertical alignment liquid crystal cell) are obtained. Comparing these experimental curves with the theoretical curves obtained from multi-layer optics theory, the director profile of vertical alignment nematic liquid crystal cell for different voltages is determined.

Selection of appropriate multilayered plate theories by using a genetic like algorithm

This paper evaluates a number of classical and refined two-dimensional theories for the analysis of metallic and composite layered plates. Thin-plate, shear deformation and higher order plate theories are compared for various plate problems related to different mechanical and geometrical boundary conditions (BCs), as well as geometries and staking sequence lay-out. The theories are implemented by referring to a Unified Formulation (UF) proposed by the first author. The UF allows displacement fields with any order N in the thickness plate direction to be introduced and any variables in the N-order displacement field to be discarded. The finite element method is applied to include anisotropy and complex BCs. The accuracy of given theories for each fixed problem is established in terms of displacement and stress fields. The best plate theories, that is the most accurate plate theories with few computational efforts, is then determined by exploring various possibilities and by selecting appropriate unknown variables upon application of genetic algorithms. A best plate curve is established which shows the best plate theories (number of terms and their meanings) in terms of accuracy. It is concluded that a best plate theory changes with changing geometry, lay-out and BCs. The genetic algorithm used allows the least expensive computational model of each given problem to be detected.

Truncated spherical voids for nearly omnidirectional optical absorption

Truncated spherical voids nanostructured tungsten films are shown to have nearly perfect absorption with characteristics of broad-band, polarization-independent and wide-incidence angle in near infrared and visible regime. Through optimizing material and structural parameters, we can achieve the absorbance above 90% from 420THz to 600THz within incidence angle from 0° to 60° for TE polarization and from 450THz to 800THz within incidence angle from 0° to 75° for TM polarization. In particular, absorbance can achieve 99.9% at 550.5THz for both polarizations under normal incidence. Such strong absorption is explained using multilayer effective media theory and cavity resonance.

Thermomechanical deformations in photovoltaic laminates

Recent experimental results based on the digital image correlation technique (U. Eitner, M. Köntges, R. Brendel, Solar Energy Mater. Solar Cells, 2010, 94, 1346–1351) show that the gap between solar cells embedded into a standard photovoltaic laminate varies with temperature. The variation of this gap is an important quantity to assess the integrity of the electric connection between solar cells when exposed to service conditions. In this paper, the thermo-elastic deformations in photovoltaic laminates are analytically investigated by developing different approximate models based on the multilayered beam theory. It is found that the temperature-dependent thermo-elastic properties of the encapsulating polymer layer are responsible for the deviation from linearity experimentally observed in the diagram relating the gap variation to the temperature. The contribution of the different material constituents to the homogenized elastic modulus and thermal expansion coefficient of the composite system is also properly quantified through the definition of weight factors of practical engineering use.

A novel extension neural network based partial discharge pattern recognition method for high-voltage power apparatus

This paper proposes a novel partial discharge (PD) pattern recognition method based on extension neural network (ENN) using fractal features. Five types of defect models are well-designed on the base of investigation of power apparatus failures. A PD detector is used to measure the raw three-dimension (3D) PD patterns, from which the fractal dimension, the lacunarity, and the mean discharges of phase windows are extracted as PD features. These critical features form the cluster domains of defect types. An ENN is then developed to recognize the pattern of partial discharge, which utilizes an extension distance (ED) instead of Euclidean distance to measure the similarities among the recognized data and the cluster domains. The ENN with simpler structure than traditional neural networks is capable of processing the clustering problems which have a range of feature values, supervised learning, continuous input, and descriptive output. Moreover, the ENN has the advantages of higher accuracy, shorter learning times, and noise tolerance, which are useful in recognizing the PD patterns of electrical apparatus. To demonstrate the effectiveness of the proposed method, comparative studies among multilayer neural network (MNN), extension theory, and K-means are conducted on 200 sets of field-test PD patterns with rather encouraging results.

A Multi-Scale Self-Correction Method for Leaking Current of Insulator in Electric Transmission Line

The insulators leakage current in transmission line can be used to characterize the filth degree of insulator surface and its accurate measurement is very important. An on-line monitor platform for insulators leakage current is introduced. Then a new multiscale self-correcting method for insulators leakage current is put forward. In this method, the leakage current information is decomposed based on multilayer and multiscale theory to gain each scale detailed signal and smooth the information in the coarsest scale at first. Furthermore, each scale detailed signal is decomposed once again and processed at different thresholds. Afterwards, the signal is reconstructed. The reconstructed detailed signal and the coarsest scale smoothed information are filtered using Kalman filter. In the end, the optimal detailed signal and the smoothed detailed signal are reconstructed and the signal is optimally estimated in the finest scale. Finally, the method was been applied to safety monitoring for a real transmission line. The results show that, compared with traditional Kalman filter method, the precision of new method raises 27%. This method has the characteristics of strong denoising ability and good robustness. It can be applied to the similar complex situation.

Constitutionalism Out of a Positivist Mind Cast: The Garantismo Way

Among contemporary forms of constitutionalism, Luigi Ferrajoli’s Garantismo may be considered as the rather unfashionable attempt to build up a comprehensive and multi-layered theory, which still takes seriously the positivist heritage. This paper offers, in brief outline, a synthetic view of the social setting, the philosophical background, and the basic features of this conception of constitutionalism, when compared with legal positivism and other mainstream forms of (neo)constitutionalism.

Husserl’s Foundation of the Formal Sciences in his “Logical Investigations”

This article is composed of three sections that investigate the epistemological foundations of Husserl’s idea of logic from the Logical Investigations. First, it shows the general structure of this logic. Husserl conceives of logic as a comprehensive, multi-layered theory of possible theories that has its most fundamental level in a doctrine of meaning. This doctrine aims to determine the elementary categories that constitute every possible meaning (meaning-categories). The second section presents the main idea of Husserl’s search for an epistemological foundation for knowledge, science and logic. Their epistemological clarification can only be reached through a detailed analysis of the structure of those intentions that give us what is meant in our intentions. To reveal the intuitive giveness of logical forms is the ultimate aim of Husserl’s epistemology of logic. Logical forms and meaning-categories can only be given in a certain higher-order intuition that Husserl calls categorical intuition. The third section of this article distinguishes different kinds of categorical intuition and shows how the most basic logical categories and concepts are given to us in a categorical abstraction.

Electromagnetic Effects and Layer Thickness Influence on Natural Characteristics of Multiferroics Composite Structure

Based on the elastic theory of anisotropic materials multilayers, using the finite element method, the dynamic characteristics are investigated for the composite structure which is composed of the electromagnetic multiferroic layer and isotropic metal layer. Firstly, the finite element model of the multilayers structure is built with shell and solid elements capable of contributing anisotropic materials. Then, based on the model analyses, the natural characteristics of the composite structure are obtained with considering the electric-magnetic-elastic effect and the layer thickness. It is also shown that the electromagnetic effects have a certain influence on the natural frequencies vibration patterns, and the thickness of the multiferroic layers has more important influence.

Overview and applicability of residual stress estimation of film–substrate structure

Residual stresses arising from thermal mismatch in layered structures rank among the major causes of mechanical failures in light-emitting diodes, integrated circuits, electronic packages, and micro-electro-mechanical systems. Applying analytical solutions to predict or calculate residual stresses’ magnitude and distribution in multilayer film–substrate system has been widely adopted by many researchers. These researches are based on multilayer theories of film–substrate systems, such as Suhir's formula, Stoney's equation, and extend Stoney's equations. To discuss and distinguish the characteristics of these approaches, finite element analysis numerical solutions and multilayer theory analytical solutions are compared and analyzed. This encompasses the theories’ application spectrum as well as their prediction capability. In addition, this work not only discusses the theories’ property and workability but also demonstrate the feasibility of the finite element method (FEM) and bilayer theories in experiment. The experimental result demonstrates that FEM is a reliable approach in predicting the mechanical behavior of multilayer structures. Hence, when calculating or predicting thin film stress using the aforementioned theories, the methodology proposed in this research can be employed to effectively validate the feasibility of these theories.

Polarized iridescence of the multilayered elytra of the Japanese jewel beetle,Chrysochroa fulgidissima

The elytra of the Japanese jewel beetle Chrysochroa fulgidissima are metallic green with purple stripes. Scanning electron microscopy and atomic force microscopy demonstrated that the elytral surface is approximately flat. The accordingly specular green and purple areas have, with normal illumination, 100-150 nm broad reflectance bands, peaking at about 530 and 700 nm. The bands shift progressively towards shorter wavelengths with increasing oblique illumination, and the reflection then becomes highly polarized. Transmission electron microscopy revealed that the epicuticle of the green and purple areas consists of stacks of 16 and 12 layers, respectively. Assuming gradient refractive index values of the layers between 1.6 and 1.7 and applying the classical multilayer theory allowed modelling of the measured polarization- and angle-dependent reflectance spectra. The extreme polarized iridescence exhibited by the elytra of the jewel beetle may have a function in intraspecific recognition.

Spectral reflectance properties of iridescent pierid butterfly wings

The wings of most pierid butterflies exhibit a main, pigmentary colouration: white, yellow or orange. The males of many species have in restricted areas of the wing upper sides a distinct structural colouration, which is created by stacks of lamellae in the ridges of the wing scales, resulting in iridescence. The amplitude of the reflectance is proportional to the number of lamellae in the ridge stacks. The angle-dependent peak wavelength of the observed iridescence is in agreement with classical multilayer theory. The iridescence is virtually always in the ultraviolet wavelength range, but some species have a blue-peaking iridescence. The spectral properties of the pigmentary and structural colourations are presumably tuned to the spectral sensitivities of the butterflies’ photoreceptors.

SiC/W/Ir multilayer-coated grating for enhanced efficiency in 50–100 nm wavelength range in Seya–Namioka mount

A broadband [SiC/W/Ir](2) multilayer coating was deposited onto a diffraction grating to enhance the grating efficiency in the 50-100 nm wavelength range in a Seya-Namioka mount. The holographic ion-beam etched grating had a laminar profile with 1200 lines/mm. The coating was designed by using the subquarterwave multilayer theory. The measurement results show that the efficiency in the -1st diffraction order is greater than 9.3% throughout the wavelength range of 50-100 nm, which is obviously higher than that of single-layer gratings with SiC, Ir, or Au coatings.

用光导波方法确定扭曲向列相液晶盒指向矢剖面

Using the optical guided wave method,the full leaky waveguide mode assembled by prism,matching fluid of refractivity and twisted nematic liquid crystal cell is studied under different voltages.Some experimental data of reflected light corresponding to different external angles through the full leaky guided mode of twisted nematic liquid crystal are obtained.From Snell law,some experimental curves between the reflectivity and the internal angle are also obtained.By comparing these experimental curves with the theoretical curves obtained from multi-layer optics theory,with a greatly good accordance,the director profile of twisted nematic liquid crystal cell for different voltages is determined.

Erōs in horasis v Plotinovem spisu O ljubezni

Članek obravnava Plotinovo teorijo ljubezni v okviru njegovega kontemplativnega nauka, ki lik Erosa kot »očesa« duše interpretira kot substancializiran odnos, čigar narava je sorodna tako duši kot predmetu njene ljubezni, ki je najvišje Lépo. Poleg tega skuša pravilno razumeti Plotinovo simboliko lika Penija iz Platonovega mita v Simpoziju; tam namreč Penija predstavlja vzrok nepopolne in nezadovoljne narave dajmonskega Erosa, pri Plotinu pa se kot še neopredeljivo zrenje vključuje celo v emanacijski proces nastanka Duše. Neopredeljiva narava, ki jo pri Plotinu predstavlja Penija, je pravzaprav odgovor na presežek Dobrega v duši, ki ga simbolizira Poros; iz nje rojeni Eros pa predstavlja gonilo kontemplativne dejavnosti Duše, ki se trudi doseči prvotno ravnovesje.

Reversing the size-dependence of surface plasmon resonances

The size-dependence of surface plasmon resonances (SPRs) is poorly understood in the small particle limit due to complex physical/chemical effects and uncertainties in experimental samples. In this article, we report an approach for synthesizing an ideal class of colloidal Ag nanoparticles with highly uniform morphologies and narrow size distributions. Optical measurements and theoretical analyses for particle diameters in the d approximately 2-20 nm range are presented. The SPR absorption band exhibits an exceptional behavior: As size decreases from d approximately 20 nm it blue-shifts but then turns over near d approximately 12 nm and strongly red-shifts. A multilayer Mie theory model agrees well with the observations, indicating that lowered electron conductivity in the outermost atomic layer, due to chemical interactions, is the cause of the red-shift. We corroborate this picture by experimentally demonstrating precise chemical control of the SPR peak positions via ligand exchange.

A thermodynamically consistent explicit competitive adsorption isotherm model based on second-order single component behaviour

A competitive adsorption isotherm model is derived for binary mixtures of components characterized by single component isotherms which are second-order truncations of higher order equilibrium models suggested by multi-layer theory and statistical thermodynamics. The competitive isotherms are determined using the ideal adsorbed solution (IAS) theory which, in case of complex single component isotherms, does not generate explicit expressions to calculated equilibrium loadings and causes time consuming iterations in simulations of adsorption processes. The explicit model derived in this work is based on an analysis of the roots of a cubic polynomial resulting from the set of IAS equations. The suggested thermodynamically consistent and widely applicable competitive isotherm model can be recommended as a flexible tool for efficient simulations of fixed-bed adsorber dynamics.