Elliptical Structure Research Articles

NGC 2022, a case study of a multiple-shell planetary nebula

ABSTRACT We present a detailed study of the physical properties, history of mass loss, and chemical abundances of the planetary nebula NGC 2022. New imaging observations obtained with the OAJ/JAST80 and NOT/ALFOSC confirm the presence of a faint ∼88 arcsec halo surrounding a double-layered elliptical structure that consists of a bright 21.4 × 16.7 arcsec inner shell and a 32 arcsec diameter envelope. The long-slit high-dispersion echelle observations obtained with MES on the OAN-SPM 2.1-m telescope can be well described by a shape model with expansion velocities of 43 ± 3 and 34 ± 3 km s−1 along the major and minor axes of the elliptical inner shell, respectively. In addition, a deep long-slit high-dispersion echelle observation made with the KPNO 4-m telescope detected line-splitting in the faint halo, revealing an expansion velocity of 15.5 ± 2 km s−1. We have also used new intermediate-dispersion optical spectra with the NOT, complemented with IUE data, to study the chemical abundances of each shell. The abundances of the three shells are typical of a Type II in the Peimbert classification of PNe and do not exhibit any notable anomalies. Finally, we estimate the total mass of NGC 2022 to be ≈0.9 M⊙, which consists of 0.64 M⊙ from the CSPN and 0.1, 0.11, and 0.1 × $f_{\mathrm{halo}}^{1/2}$ M⊙ from the ionized inner shell, outer shell, and halo, respectively.

Analysis of dynamic characteristics of liquid-lubricated mechanical face seals with inclined elliptical grooves

PurposeThe purpose of this paper is to study the dynamic characteristics of mechanical face seals with liquid-lubricated inclined elliptical grooves.Design/methodology/approachThe steady-state and perturbation Reynolds control equations of liquid films were established. The film pressure and the liquid film dynamic coefficients were obtained, impacts of groove structures on the liquid film dynamic characteristic coefficients were analyzed.FindingsThe analysis results indicate that the axial dynamic stiffness and damping coefficients of the liquid film seal with inclined elliptical grooves are far greater than those of the angular directions. Furthermore, the dynamic stiffness coefficient of the liquid film with the nonclosed inclined elliptical grooves is higher than those with the closed grooves, whereas the dynamic damping coefficient of the liquid film is lower.Originality/valueThe effects of inclined elliptical groove structures on the dynamic characteristics of the liquid film seal are investigated. The results presented are expected to enrich the theoretical basis of optimizing the dynamic performance of liquid film seals with textures.

The inverse Mellin transform via analytic continuation

We present a method to calculate the x-space expressions of massless or massive operator matrix elements in QCD and QED containing local composite operator insertions, depending on the discrete Mellin index N, directly, without computing the Mellin-space expressions in explicit form analytically. Here N belongs either to the even or odd positive integers. The method is based on the resummation of the operators into effective propagators and relies on an analytic continuation between two continuous variables. We apply it to iterated integrals as well as to the more general case of iterated non-iterative integrals, generalizing the former ones. The x-space expressions are needed to derive the small-x behaviour of the respective quantities, which usually cannot be accessed in N-space. We illustrate the method for different (iterated) alphabets, including non-iterative 2F1 and elliptic structures, as examples. These structures occur in different massless and massive three-loop calculations. Likewise the method applies even to the analytic closed form solutions of more general cases of differential equations which do not factorize into first-order factors.

Construction of 4 × 4 Substitution Box Using Elliptic Curves and Algebraic Group Structures

Construction of 4 × 4 Substitution Box Using Elliptic Curves and Algebraic Group Structures

Case Study: Roof Truss Structure With Large Cut Out and Elliptic Glazing Surface

The article presents the technical solutions implemented during the design of the roof trusses and the elliptic skylight structure (Figure. 1) for the extension of the "Shopping City Sibiu" commercial centre in Romania. The area of the roof structure was approximately 1600 sqm (29x56 m). In the central region of the roof, a 27 m long and 10 m wide elliptic skylight was placed. The challenges of the project arouse from the relatively large span of the structure, being supported only on 13 non-symmetrically placed perimeter concrete columns. Thus, the structure had to be designed in such a way, that it would support the extra 20 tones coming from the skylight structure, while also bring inside the natural light unobstructed by any main structural elements. The relatively large deformations between the supporting points of the skylight under variable loads (especially snow loads) can also have adverse effects on the glazing surface during operational phase. Due to this, also the serviceability limit state checks had an important role in the engineering calculations. The structural configuration steps with performed analyses on the partial structural models and on the complex 3D model were especially useful for the identification of the sensitive zones, helping to create the surface shape and develop adequate structural details. The paper summarizes the structural engineering challenges during the design and execution process.

Synonymic monopredicative utterances with the interjectional head lexeme (based on French fiction of the 20th – the 21st centuries)

In this article interjectional monopredicative utterances (MPU) of modern French fiction are defined as compressed one-basis (with one transformational terminal chain) synonymic transforms of virtual (linguistic) primary proposition actualized in the form of mono- and polysynonymic (with the intra-, interphrastic and intra-interphrastic bi- and polysynonymy) elliptic complex lingua-discursive signs‑preferential options with the interjectional head lexeme.
 The goal of this research is to identify the structural and semantic types and to reveal the co(n)textual (linguistic and / or situational) functions of the interjectional MPU of French fiction of the 20th – the 21st centuries and to determine the degree of their co(n)textual pertinence.
 In this article they use the procedure of the inverse reconstruction (discourse → language) of virtual transformational processes with the aim to identify the primary proposition of each synonymic transform; and the «alternative» linguistic experiment consisting in the artificial substitution by the addresser of some utterance of the analyzed discursive fragment with the synonymic utterance that allows to determine the degree of co(n)textual pertinence of all the members of virtual synonymic chains.
 It is revealed that in the synonymic interjectional MPU with non-derivative (primary) interjections of modern French fiction the author doesn’t exteriorize the structure subject + personal performative predicate with the referentially determined or non-determined actant, explicated in the contact, interphrastic or distant co(n)text (+ circumstance) and the existential structure c’est with the demiactive (active and passive simultaneously) actant referentially non-determined or determined in the intra- or interphrastic co(n)text. The structural and semantic (qualificative, processual, emotional-specificative, volitional-specificative) types of interjectional elliptic structures are distinguished, their co(n)textual functions are revealed and the degree of their co(n)textual pertinence, according to the pragmatic planification of the narration or to the author’s idiostylistic peculiarities, is justified.

Anisotropic vortex core in the nematic state in electron-doped iron-pnictide superconductors

We investigated the vortex states in the electron-doped BaFe1.8Co0.2As2 using Bogoliubov-de Gennes equations, based on a phenomenological model with competing nematic order and extended s-wave superconductivity. Specifically, we considered the spin-driven nematic order for the optimally doped compound. Our findings suggest that there are no Andreev bound states at the Fermi energy in the nematic phase, and the local density of states exhibits a double-peak structure, consistent with scanning tunneling microscopy experiments. Moreover, we propose an elliptic vortex structure in the local density of states map, which we attribute to the presence of the nematic order.

Central limit theorem of linear spectral statistics of high-dimensional sample correlation matrices

A high-dimensional sample correlation matrix is an important random matrix in multivariate statistical analysis. Its central limit theory is one of the main theoretical bases for making statistical inferences on high-dimensional correlation matrices. Under the high-dimensional framework in which the data dimension tends to infinity proportionally with the sample size, we establish the central limit theorems (CLT) for the linear spectral statistics (LSS) of sample correlation matrices in two settings: (1) the population follows an independent component structure; (2) the population follows an elliptical structure, including some heavy-tailed distributions. The results show that the CLTs of the LSS of the sample correlation matrices are very different in the two settings. In particular, even if the population correlation matrix is an identity matrix, the CLTs are different in the two settings. An application of our two established CLTs is provided.

LEXICAL AND STYLISTIC FEAUTURES OF ANTI-WAR PROSE BY E.M. REMARQUE AND ISSUES OF THEIR TRANSLATION

The article deals with lexical and stylistic features of anti-war prose by a German-born novelist E.M. Remarque and analyzes issues of their translation. It has been revealed that anti-war prose by E.M. Remarque is characterized by the use of lexical and syntactic language means. Everyday vocabulary, phraseologisms, emotional and expressive language units, filler words play key role among the means of colloquial language implementation. Features of literary and colloquial syntax of novels by E.M. Remarque include extensive use of question and imperative sentences, simple sentences in dialogues, lexical repetitions, elliptical structures.

Charge density wave-templated spin cycloid in topological semimetal NdSbxTe2−x−δ

Magnetic topological semimetals present open questions regarding the interplay of crystal symmetry, magnetism, band topology, and electron correlations. Ln${\mathrm{Sb}}_{x}{\mathrm{Te}}_{2\text{\ensuremath{-}}x\text{\ensuremath{-}}\ensuremath{\delta}}$ (Ln denotes Lanthanide) is a family of square-net-derived topological semimetals that allows compositional control of band filling, and access to different topological states via an evolving charge density wave (CDW) distortion. Previously studied Gd and Ce members containing a CDW have shown complex magnetic phase diagrams, which implied that spins localized on Ln interact with the CDW, but to this date no magnetic structures have been solved within the CDW regime of this family of compounds. Here, we report on the interplay of the CDW with magnetism in ${\mathrm{NdSb}}_{x}{\mathrm{Te}}_{2\text{\ensuremath{-}}x\text{\ensuremath{-}}\ensuremath{\delta}}$ by comparing the undistorted square net member ${\mathrm{NdSb}}_{0.94}{\mathrm{Te}}_{0.92}$ with the CDW-distorted phase ${\mathrm{NdSb}}_{0.48}{\mathrm{Te}}_{1.37}$, via single-crystal x-ray diffraction, magnetometry, heat capacity, and neutron powder diffraction. ${\mathrm{NdSb}}_{0.94}{\mathrm{Te}}_{0.92}$ is a collinear antiferromagnet with ${T}_{N}\ensuremath{\sim}2.7\phantom{\rule{4pt}{0ex}}\mathrm{K}$, where spins align antiparallel to each other, but parallel to the square net of the nuclear structure. ${\mathrm{NdSb}}_{0.48}{\mathrm{Te}}_{1.37}$ exhibits a nearly fivefold-modulated CDW (${q}_{\text{CDW}}=0.18$), isostructural to other Ln${\mathrm{Sb}}_{x}{\mathrm{Te}}_{2\text{\ensuremath{-}}x\text{\ensuremath{-}}\ensuremath{\delta}}$ at similar $x$. ${\mathrm{NdSb}}_{0.48}{\mathrm{Te}}_{1.37}$ displays more complex magnetism with ${T}_{N}=2.3\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, additional metamagnetic transitions, and an elliptical cycloid magnetic structure with ${q}_{\text{mag}}=\ensuremath{-}0.41{\mathrm{b}}^{*}$. The magnitudes of ${q}_{\text{CDW}}$ and ${q}_{\text{mag}}$ exhibit an integer relationship, $1+2{q}_{\text{mag}}={q}_{\text{CDW}}$, implying a coupling between the CDW and magnetic structure. Given that the CDW is localized within the nonmagnetic distorted square net, we propose that conduction electrons ``template'' the spin modulation via the Ruderman-Kittel-Kasuya-Yosida interaction.

Design of a photonic crystal fiber polarization beam splitter with simple structure and ultra-wide bandwidth

A novel polarization beam splitter (PBS) based on dual-core photonic crystal fiber (DC-PCF) is proposed in this work. The proposed DC-PCF PBS contains two kinds of lattices and three kinds of air holes to form the asymmetrical elliptic dual-core structure. By using the full-vector finite element method, the propagation characteristics of the proposed DC-PCF PBS are investigated. The simulation results show that the bandwidth of the proposed DC-PCF PBS can reach to 340 nm, which covers the S + C + L + U communication bands, the shortest splitting length is 1.97 mm, and the maximum extinction ratio appears near wavelength 1550 nm. Moreover, the insertion loss of the proposed DC-PCF PBS is very low. It is believed that the proposed DC-PCF PBS has important applications in the field of all-optical communication and network.

Electric split-ring metamaterial based microfluidic chip with multi-resonances for microparticle trapping and chemical sensing applications

In this work, an integration of terahertz (THz) electrical split-ring metamaterial (eSRM) with microfluidic chip is presented. This eSRM-based microfluidic chip exhibits multiple resonances in the THz spectrum and trapping selectively microparticle size characteristics. The arrangement of eSRM array is dislocation. It generates the fundamental inductive-capacitive (LC) resonant mode, quadrupole, and octupolar plasmon resonant modes and then exhibits high sensitivity to the environmental refraction index. The trapping structures of microparticles are elliptical barricades on eSRM surface. Thus, the electric field energy is strongly confined within the gap of eSRM in transverse electric (TE) mode and then the elliptical trapping structures are anchored on both sides of the split gap to ensure the microparticles can be trapped and located on the gap. To imitate the microparticle sensing ambient environment qualitatively and quantitatively in the THz spectrum, the microparticles are designed different feature sizes with different refraction index from 1.0 to 2.0 in ethanol medium. The results show the proposed eSRM-based microfluidic chip possesses the trapping and sensing abilities in single microparticle and high sensitivity for fungus, microorganism, chemical and environmental applications.

Theoretical analysis of hybrid surface plasmon polaritons in plasma-based elliptical structures with graphene layers for THz applications

Theoretical analysis of hybrid surface plasmon polaritons in plasma-based elliptical structures with graphene layers for THz applications

Chrystal Ann Chemris. The Spanish Baroque and Latin American Literary Modernity: Writing in Constellation

Chrystal Ann Chemris. <i>The Spanish Baroque and Latin American Literary Modernity: Writing in Constellation</i>

Spectral characteristics of the integral operator of the internal problem of electrodynamics for elliptical frame structure

The article is devoted to the analysis of electrodynamic properties elliptical frame structure. Taking into account double symmetry internal problem of electrodynamics for the structure under consideration in the framework of the thin-wire approximation is reduced to four integral Fredholm equations of the first kind, written with respect to independent current functions. A study of spectral characteristics of the integral operators of the corresponding integral equations for various values of the electrical length and ellipticity of the frame. It is shown that the eigenfunctions of integral operators for close values of these parameters have a high degree of correlation, with In this case, the eigenfunctions are close in form to trigonometric functions. Features of the frequency dependence of the eigenvalues integral operators. The conclusion is made about the resonant nature of these dependences, what makes an elliptical frame structure in many respects similar to the previously considered tubular vibrator and spherical spiral particle. The results presented in the article form an in-depth understanding of the processes occurring in the structure under consideration, and also serve as a guideline in the construction of approximation models for solving the internal tasks.

Determination of Magnetic Structures in Magnetic Microwires with Longitudinally Distributed Magnetic Anisotropy.

We studied the magnetic properties of a glass-covered amorphous microwire that was stress-annealed at temperatures distributed along the microwire length. The Sixtus-Tonks, Kerr effect microscopy and magnetic impedance techniques have been applied. There was a transformation of the magnetic structure across the zones subjected to annealing at different temperatures. The annealing temperature distribution induces the graded magnetic anisotropy in the studied sample. The variety of the surface domain structures depending on the longitudinal location has been discovered. Spiral, circular, curved, elliptic and longitudinal domain structures coexist and replace each other in the process of magnetization reversal. The analysis of the obtained results was carried out based on the calculations of the magnetic structure, assuming the distribution of internal stresses.

Theoretical, numerical, and experimental study on quasi-static compressive behaviors of elliptical anti-chiral auxetic structure

Theoretical, numerical, and experimental study on quasi-static compressive behaviors of elliptical anti-chiral auxetic structure

Embroidered Annular Elliptical E-Textile Antenna Sensor for Knee Effusion Diagnosis

This article presents the design of a wearable textile antenna sensor for knee effusion diagnosis application. According to human anatomy, effusion is the collection of synovial fluid in a specific anatomic space. Knee effusion, often known as water on the knee, is a condition in which excess fluid collects around the knee joint. The antenna sensing patch region is embroidered using an automated computerized embroidery machine, while the design parameters were optimized using machine learning (ML) algorithms, including deep neural network (DNN). For the best fit on a knee joint, an annular elliptical structure of electronic textile (E-textile) antenna sensor is developed. Pure silver-coated highly conductive thread with improved flexibility is used for embroidering the patchwork in order to enhance the feasibility of the proposed device. The fabricated antenna sensor has the operating resonance frequency at 2.19 GHz and performs diagnosis based on the concept of reflection coefficient parameter. Furthermore, the specific absorption rate (SAR) level of a proposed sensor device is being evaluated on the knee joint and has been kept below the safety limit value of 1.6 W/kg averaged over 1 g of tissue model.

Mapping the shape and dimension of three-dimensional Lagrangian coherent structures and invariant manifolds

We introduce maps of Cauchy–Green strain tensor eigenvalues to barycentric coordinates to quantify and visualize the full geometry of three-dimensional deformation in stationary and non-stationary fluid flows. As a natural extension of Lagrangian coherent structure diagnostics, which provide separate scalar fields and a one-dimensional quantification of fluid deformation, our barycentric mapping visualizes the role of all three Cauchy–Green eigenvalues (or rates of stretching) in a single plot through a novel stretching coordinate system. The coordinate system is based on the distance from three distinct limiting states of deformation that correspond with the dimension of the underlying invariant manifolds. One-dimensional axisymmetric deformation (sphere to rod deformation) corresponds to one-dimensional unstable manifolds, two-dimensional axisymmetric deformation (sphere to disk deformation) corresponds to two-dimensional unstable manifolds and the rare three-dimensional isometric case (sphere to sphere translation and rotation) corresponds to shear-free elliptic Lagrangian coherent structures (LCSs). We provide methods to visualize the degree to which fluid deformation approximates these limiting states, and tools to quantify differences between flows based on the compositional geometry of invariant manifolds in the flow. We also develop a simple analogue for bilinearly representing and plotting both rates of stretching and rotation as a single vector. As with other LCS techniques, these diagnostics define frame-indifferent material features in the flow. We provide multiple computed examples of LCS and momentum transport barriers, and show advantages over other coherent structure diagnostics.

Symmetries of Calabi-Yau prepotentials with isomorphic flops

Calabi-Yau threefolds with infinitely many flops to isomorphic manifolds have an extended Kähler cone made up from an infinite number of individual Kähler cones. These cones are related by reflection symmetries across flop walls. We study the implications of this cone structure for mirror symmetry, by considering the instanton part of the prepotential in Calabi-Yau threefolds. We show that such isomorphic flops across facets of the Kähler cone boundary give rise to symmetry groups isomorphic to Coxeter groups. In the dual Mori cone, non-flopping curve classes that are identified under these groups have the same Gopakumar-Vafa invariants. This leads to instanton prepotentials invariant under Coxeter groups, which we make manifest by introducing appropriate invariant functions. For some cases, these functions can be expressed in terms of theta functions whose appearance can be linked to an elliptic fibration structure of the Calabi-Yau manifold.