Dense Elements Research Articles

Uniform circular photonic bandgap structures (PBGSs) for harmonic suppression of a bandpass filter

Conventional 2-D uniform hole patterned photonic bandgap structures (PBGSs) have been replaced by 1-D uniform circular PBGSs as they provide very similar performances. This concept is utilized to investigate the effectiveness in harmonic suppression. They have been applied in harmonic suppression of an asymmetric coupled line bandpass filter (BPF). It can be seen that the proposed 1-D uniform circular PBGSs under the lines of a BPF yield performance better than other different designs such as conventional 2-D uniform PBGSs and dense PBG elements including few more designs. Such designs are more compact than available designs reported in the open literature.

High-Speed Prediction of Strict Numerical Solutions Using Multiadaptive-Meshing

In this paper, we propose a method to predict the strict numerical solution, which will be given by the infinitely dense finite element mesh, from the solutions obtained by several different meshes generated by the adaptive meshing method. The proposed method is applied to characteristics calculation of several kinds of motors to verify the validity and usefulness. It is clarified that the proposed method gives accurate results with short calculation time. The method is also useful to understand the required mesh in each analyzed model

A hybrid finite element formulation for a beam-plate system

A new development in the area of the hybrid finite element analysis (hybrid FEA) is presented. The hybrid FEA method combines the conventional FEA method with energy FEA (EFEA) for analysis of systems that contain both flexible and stiff members. A formulation for analyzing flexible plates spot-welded to stiff beams when the excitation is applied on the stiff members is developed. Conventional FEA models are employed for modeling the behavior of the stiff members in a system. Appropriate damping elements are introduced in the connections between stiff and flexible members in order to capture the presence of the flexible members during the analyses of the stiff ones. The component mode synthesis method is combined with analytical solutions for determining the driving point conductance at joints between stiff and flexible members and for defining the properties of the damping elements which represent the flexible members when analyzing the stiff components. Once the vibration of the stiff members and the amount of power dissipated at the damping elements has been identified, an EFEA analysis is performed in order to determine the amount of vibrational energy in the flexible members. The new developments are validated by comparing results of the hybrid FEA with results from very dense conventional finite element analyses for structures of increasing complexity.

Negation in bounded commutative DRℓ-monoids

The class of commutative dually residuated lattice ordered monoids (DRℓ-monoids) contains among others Abelian lattice ordered groups, algebras of Hájek’s Basic fuzzy logic and Brouwerian algebras. In the paper, a unary operation of negation in bounded DRℓ-monoids is introduced, its properties are studied and the sets of regular and dense elements of DRℓ-monoids are described.

Subcellular localization of hepatitis C virus structural proteins in a cell culture system that efficiently replicates the virus.

Due to the recent development of a cell culture model, hepatitis C virus (HCV) can be efficiently propagated in cell culture. This allowed us to reinvestigate the subcellular localization of HCV structural proteins in the context of an infectious cycle. In agreement with previous reports, confocal immunofluorescence analysis of the subcellular localization of HCV structural proteins indicated that, in infected cells, the glycoprotein heterodimer is retained in the endoplasmic reticulum. However, in contrast to other studies, the glycoprotein heterodimer did not accumulate in other intracellular compartments or at the plasma membrane. As previously reported, an association between the capsid protein and lipid droplets was also observed. In addition, a fraction of labeling was consistent with the capsid protein being localized in a membranous compartment that is associated with the lipid droplets. However, in contrast to previous reports, the capsid protein was not found in the nucleus or in association with mitochondria or other well-defined intracellular compartments. Surprisingly, no colocalization was observed between the glycoprotein heterodimer and the capsid protein in infected cells. Electron microscopy analyses allowed us to identify a membrane alteration similar to the previously reported "membranous web." However, no virus-like particles were found in this type of structure. In addition, dense elements compatible with the size and shape of a viral particle were seldom observed in infected cells. In conclusion, the cell culture system for HCV allowed us for the first time to characterize the subcellular localization of HCV structural proteins in the context an infectious cycle.

A vibration analysis of stiffened plates under heavy fluid loading by an energy finite element analysis formulation

An energy finite element analysis (EFEA) formulation for high frequency vibration analysis of stiffened plates under heavy fluid loading is presented. The added mass effect and the radiation damping effect due to the fluid loading are incorporated in the derivation of the EFEA governing differential equations. In addition, the fluid loading effect and the presence of a stiffener are accounted when computing the power transfer coefficients through plate/stiffener junctions. The effect of the fluid on power transfer coefficients of a plate/stiffener junction is analyzed and discussed. The new formulation is validated by comparing EFEA results to solutions by very dense finite element models for several plate/stiffener assemblies, which include two coplanar plates connected by a stiffener, two plates connected at a 45° angle by a stiffener, and a section of a typical naval structure. All plates are considered in contact with dense fluid from one side. The energy ratios between the receiving sections of the plates and the excited sections of the plates are computed and good correlations are observed between the EFEA and the very dense FEA results.

Data-sparse algebraic multigrid methods for large scale boundary element equations

This paper presents new algebraic multigrid (AMG) preconditioners for data-sparse boundary element matrices arising from the adaptive cross approximation (ACA) to dense boundary element matrices. Here we mainly consider the single layer potential integral equation, resulting from the direct boundary integral formulation of the interior, or exterior Dirichlet boundary value problems for the Laplace equation in two, or three spatial dimensions, as the most interesting boundary integral equation. The standard collocation, or Galerkin boundary element discretizations lead to fully populated system matrices which require O ( N h 2 ) of storage units and cause the same complexity for a single matrix-by-vector multiplication, where N h denotes the number of boundary unknowns. Data-sparse matrix approximation schemes such as ACA reduce this complexity to an almost linear behavior in N h . Since the single layer potential operator is a pseudo-differential operator of the order −1, the resulting boundary element matrices have large condition numbers on fine meshes. Iterative solvers dramatically suffer from this property for growing N h . Our AMG-preconditioners avoid the increase of the iteration numbers and result in almost optimal solvers with respect to the total complexity. This behavior is confirmed by our numerical experiments. Let us mention that our AMG-preconditioners use only single grid information provided by the ACA system matrix and by the usual mesh data on the finest level anyway. Similar results are valid for the hypersingular integral operator that is easier to handle since it is a pseudo-differential operator of the order +1.

An energy finite element formulation for high-frequency vibration analysis of externally fluid-loaded cylindrical shells with periodic circumferential stiffeners subjected to axi-symmetric excitation

A hybrid method is developed for predicting the high-frequency vibration response of fluid-loaded cylindrical shells with periodic circumferential stiffeners. In this method, the cylindrical shell is modeled using the Energy Finite Element Analysis (EFEA) method which includes added mass and radiation effects due to the surrounding exterior fluid medium. The joint matrices of the EFEA formulation at the location of the periodic stiffeners are computed based on Periodic Structure (PS) theory. Thus, the periodicity effects such as pass/stop characteristics are captured in the EFEA solution. The hybrid EFEA-PS method is used to analyze the vibration of a fluid-loaded axisymmetric cylindrical shell with periodic circumferential stiffeners. The flexural energy stored in each periodic section is computed. The results are compared with the solution produced by a very dense axisymmetric Finite Element (FE) model with infinite finite elements for the fluid domain. The good correlation indicates that the new hybrid method captures properly both the heavy fluid effects of the exterior fluid medium and the periodicity characteristics due to periodic stiffeners.

No effect of spatial phase randomisation on direction discrimination in dense random element patterns

Two computational strategies have been proposed for motion analysis in the human visual system. Energy-based schemes involve detection of spatiotemporal Fourier energy in the frequency components comprising a moving pattern. Edge-based schemes track shifts in the position of local edges in the pattern over time. This paper describes a stimulus manipulation, spatial phase randomisation, that acts as a diagnostic test for the involvement of energy-based processes, and describes the results of two experiments which apply the manipulation to random element patterns. Both experiments compared direction discrimination performance in patterns before and after the spatial phase of their components was randomised in the Fourier domain. For dense patterns, there was no effect of phase randomisation on the maximum displacement supporting reliable direction discrimination, indicating that energy-based responses were dominant. For sparse patterns, a significant effect of phase randomisation was obtained, indicating a greater role for edge-based responses.

Reinvestigation of spermiogenesis in the proteocephalidean cestode Proteocephalus longicollis (Zeder, 1800).

The reinvestigation of spermiogenesis in the proteocephalidean cestode Proteocephalus longicollis (Zeder, 1800) provides new details that were not described previously for this species. The 2 centrioles with roots are oriented at the first tangential to the long axis of the nucleus in a differentiation zone. They come to be arranged in the same plane only when a single intercentriolar body (ICB) appears between them. The ICB had been described previously as consisting of a number of dense elements (Swiderski, 1985) but, in the present study, appeared as a single, electron-dense plate. Also new for this species is the observation of 2 arching membranes that appear at the base of the differentiation zone only when the 2 flagella rotate toward the median cytoplasmic protrusion. Moreover, the formation of a crested body is described for the first time in P. longicollis. The present data support the suggestion that the process of spermiogenesis in proteocephalidean tapeworms corresponds in most features to that observed in some members of the unrelated tetraphyllidean clades, the Onchobothriidae and Phyllobothriidae. This may represent more evidence regarding the close relationship between tetraphyllidean and proteocephalidean cestodes, but existing information is fragmentary and controversial in some characters.

Algebraic Multigrid Preconditioners for Sparse Approximations of Boundary Element Matrices

AbstractThis paper presents new algebraic multigrid preconditioners for sparse representations of boundary element matrices which arise from the so‐called adaptive‐cross‐approximation to dense boundary element matrices resulting from the standard collocation, or Galerkin boundary element discretization of the single layer potential operator.

Modelling crack propagation in concrete structures with a two scale approach

AbstractA simplified computational technique based on a refined global–local method is applied to the failure analysis of concrete structures. The technique distinguishes the scale of the structure, modelled with large size finite elements, from the scale at which material non‐linearity occurs due to progressive cracking and macro‐crack propagation. The finite element solution is split into two parts: a linear elastic analysis on a coarse mesh over the entire structure and a non‐linear analysis over a small part of the structure where a dense finite element grid is employed. In the non‐linear calculation, a non‐local damage model is implemented. These two computations are coupled with the help of an iterative scheme. The size and location of the region where a non‐linear analysis is performed, is adapted to follow the development of the damage zone. Numerical examples of mode I fracture of concrete specimens with straight and curved cracks are presented. Copyright © 2003 John Wiley & Sons, Ltd.

High-resolution pattern generation using the epoxy novolak SU-8 2000 resist by electron beam lithography

We report the fabrication of high-resolution sub 50 nm patterns by electron beam lithography using the epoxy novolak SU-8 2000 resist formulation. The minimum linewidth achieved is on the order of 30 nm and corresponds to a threefold reduction in minimum linewidth over previous reports describing similar resist chemistries. Our results also show that it is possible to fabricate dense linear grating elements without proximity correction. The dry etch resistance of native SU-8 2000 was found to be nearly twice that of poly(methylmethacrylate), making it ideal for applications that require pattern transfer. These studies are intended to explore the feasibility of SU-8 2000 as an electron beam resist for pattern generation on length scales below 50 nm.

H�jek basic fuzzy logic and ?ukasiewicz infinite-valued logic

Using the theory of BL-algebras, it is shown that a propositional formula ϕ is derivable in Łukasiewicz infinite valued Logic if and only if its double negation ˜˜ϕ is derivable in Hajek Basic Fuzzy logic. If SBL is the extension of Basic Logic by the axiom (φ & (φ→˜φ)) → ψ, then ϕ is derivable in in classical logic if and only if ˜˜ ϕ is derivable in SBL. Axiomatic extensions of Basic Logic are in correspondence with subvarieties of the variety of BL-algebras. It is shown that the MV-algebra of regular elements of a free algebra in a subvariety of BL-algebras is free in the corresponding subvariety of MV-algebras, with the same number of free generators. Similar results are obtained for the generalized BL-algebras of dense elements of free BL-algebras.

Partitioned R-matrixtheory

The traditional implementation of R-matrix theory to electronscattering and photoionization requires the computationallydemanding diagonalization of dense symmetric matrices ofHamiltonian elements. To make this task more efficient and toimprove the convergence of the R-matrix basis, we develop analternative R-matrix theory based on partitioning theeigenvectors and eigenvalues into a group of accurately knownlow-lying ones and derive an approximation to account for theremainder. We give the appropriate expressions for the R-matrix,its energy derivative, and the dipole matrix in this basis.Scattering from a diffuse hydrogen-like oxygen target withn⩽8 states is used to illustrate the convergence ofthe method.

An alternative energy finite element formulation based on incoherent orthogonal waves and its validation for marine structures

An alternate formulation is presented for deriving the governing differential equations of the energy finite element analysis (EFEA). The formulations for interior acoustic spaces and for thin plates are presented. The new formulations are based on considering the acoustic or the flexural response as a summation of incoherent orthogonal waves. The validity of the EFEA is demonstrated by comparing vibration results from very dense conventional finite element models to EFEA results. Actual marine structures are analyzed. Comparison between statistical energy analysis and EFEA is also performed for a vessel that is comprised by both acoustic spaces and structural components. Good agreement is demonstrated between the two methods and the validity of the EFEA is established.

Mass absorption coefficient of tungsten for 1600–2100 eV

The transmission of soft x rays with photon energies from 1606 eV to 2106 eV was measured for tungsten using thin-film samples and a synchrotron source. This region includes the ${M}_{\mathrm{IV}}$ and ${M}_{\mathrm{V}}$ edges. The two tungsten films had thicknesses of $107.7\ifmmode\pm\else\textpm\fi{}10 \mathrm{nm}$ and $51.5\ifmmode\pm\else\textpm\fi{}10 \mathrm{nm};$ the intensity of the transmitted x rays was measured with a silicon photodiode. The values for the mass absorption coefficient reported here were determined from the ratios of the transmission through the two samples, i.e., through a net $56.2\ifmmode\pm\else\textpm\fi{}14 \mathrm{nm}$ of tungsten, and some additional constant factors. The ${M}_{\mathrm{V},\mathrm{I}\mathrm{V}}$ edges have widths (10%--90% after background subtraction) of $33\ifmmode\pm\else\textpm\fi{}5 \mathrm{eV}$ and $28\ifmmode\pm\else\textpm\fi{}5 \mathrm{eV},$ respectively, compared to zero width in all x-ray tables based on atomic form factors and to 41 eV and 44 eV within a real-space multiple-scattering theory. The measurements are relevant to microspectroscopy and microtomography of integrated circuit interconnects and may be applicable to accurate measurement of the mass absorption coefficients of similar dense elements.

Neuronal localization of sterol regulatory element binding protein-1 in the rodent and primate brain: a light and electron microscopic immunocytochemical study

Sterol regulatory element binding proteins are membrane-bound transcription factors that activate expression of several genes controlling cellular cholesterol and fatty acid homeostasis. The present study aimed to investigate the in vivo expression of sterol regulatory element binding protein-1 in the normal rodent and primate brain, and in the brain in Niemann–Pick type C disease mice. These mutant animals have lysosomal cholesterol accumulation and progressive neurodegeneration caused by an inactivating mutation of the NPC1 gene whose protein product functions in vesicular lipid trafficking. Western blot analysis of rat hippocampal homogenates with an affinity purified rabbit polyclonal antibody directed against an internal epitope of sterol regulatory element binding protein-1 identified a major 68,000 mol. wt protein consistent with the amino-terminal, transcriptionally active fragment of sterol regulatory element binding proteins-1. Immunocytochemically, this antibody revealed dense sterol regulatory element binding protein-1 staining of nuclei and light staining of the cytoplasm of cells in the neocortex and hippocampus in the rat, mouse and monkey brain. By electron microscopy of immunogold-labeled brain sections, these densely labeled cells were found to be neurons. In contrast, normal glial cells had little or no sterol regulatory element binding protein-1 immunoreactivity even at a developmental stage (postnatal day 9) which coincides with active myelination in the rat brain. Also, in contrast to the normal mouse brain, Niemann–Pick type C mice showed reduced staining of cortical and hippocampal neuronal nuclei. Since sterol regulatory element binding protein-1 has been shown to be a transcriptional regulator of fatty acid synthesis in vivo, the current findings of a predominantly neuronal nuclear expression of the 68,000 mol. wt transcriptionally active fragment of sterol regulatory element binding protein-1 highlights the established role of phospholipid metabolites and other fatty-acid containing lipids in neuronal signal transduction and other neuronal functions. Reduced sterol regulatory element binding protein-1 expression in neurons in Niemann–Pick type C may reflect a deficiency in fatty acid synthesis that could contribute to the neuronal dysfunction in this disorder.

Anatomical bases of glottic widening surgery related to arytenoidectomy.

Derived from arytenoidectomy, different surgical techniques have been developed for widening the glottis in cases of bilateral vocal cord paralysis. Their anatomical bases were reinvestigated in plastinated serial sections of 25 adult human larynges. At the anterolateral surface of the arytenoid cartilage, blood vessels crossing the crista arcuata may cause bleeding complications. The arytenoid cartilage is related to three major histologic complexes which must be taken into account during surgery. The dense connective tissue complex consists of the cricoarytenoid ligament and the conus elasticus, which are connected ventrocaudally. The cricoarytenoid ligament and the vocal cord are separated by the cartilaginous inscription of the vocal process. The muscular complex consists of the transverse arytenoid muscle, which is the posterior wall of the glottis, and the thyroarytenoid muscle, which is intimately fixed to the conus elasticus near the arytenoid cartilage. The loose connective tissue complex is represented by the vestibular fold, containing adipose tissue, mucous glands, few collagenous fiber septa, and at its posterior end, a small cranial extension of the vocal cord. For glottic widening surgery, the arytenoid cartilage must be regarded as an integrated component of an extended fibro-cartilaginous framework supporting the laryngeal airway. Shrinking processes of the dense connective tissue elements may complicate surgical interventions. Iatrogenic lesions of the posterior glottis should be avoided to prevent the development of synechia or insufficient closure of the larynx during swallowing.

Performance Evaluation of a Titania-coated Reticulated Foam Photocatalytic Oxidation Reactor

AbstractWe have constructed and evaluated the performance of a gas-solid annular photocatalytic oxidation reactor that incorporates an alumina reticulated foam monolith element as a titania catalyst support. The reticulate occupies the annular region formed by the lamp and the outer reactor tube. Three alumina reticulates possessing different mean pore sizes and pore densities, designated as 10, 20 and 30 pores-per-inch (PPI) were employed. The reticulates were wash-coated with Degussa P25 titania. Light transmittance measurements through the reticulates showed that 30 PPI reticulate, the least optically dense element, captures the most light. Photocatalytic oxidation of dilute isopropanol (IPA) in air was chosen as the probe reaction to assess the performance of each reticulate- catalyst coating configuration. Process parameters varied were inlet IPA concentration, incident UV intensity, and mean gas residence time. For similar catalyst loadings, the 30 PPI reticulate outperformed both the 20 and 10 PPI reticulates, while the 20 PPI reticulate modestly outperformed the 10 PPI reticulate. With increasing titania coating yielding thicker titania films, general performance increases until a critical thickness is achieved. Light intensity measurements and simple forward UV intensity profile calculations reveal that reticulate performance is largely governed by the UV intensity profile. For a given reticulate, results suggest that the optimum thickness of the TiO