Asymmetric Elements Research Articles

DEVELOPMENT OF ADVANCED THERMOSTRENTHENING TECHNIQUE FOR ENVIRONMENTAL PROBLEM SOLUTION IN METALLURGICAL INDUSTRY

Oil quenching of complex bodies with asymmetric elements is a fi re hazardous, high-cost and out-of-control process. Joint bar is one of complex bodies with asymmetric confi guration. This type of heat treatment is applicable for it to meet the Technical requirements. Ecologically friendly technique and water regulated cooling device of joint bar have been developed by OJSC «VNIIMT». Due to using water as a coolant polluting emissions into the atmosphere has been completely eliminated, so there is no need of oil purchase, its replacement and disposal. Test-bench experiments at the pilot-production set resulted in obtaining the requirement level of mechanical properties in accordance with the Technical requirements. Joint bar linearity has been provided by water separate supply for each section of the pipeline. The presented results have given occasion to acquisition of controlled cooling device process conditions. The proposed technique can replace successfully a conventional one – oil quenching.

Pentamode metamaterials with asymmetric double-cone elements

Pentamode metamaterials are a very interesting set of artificial solids. They are difficult to compress but flow easily, hence imitating somehow the behaviours of liquids. In this paper, three-dimensional (3D) pentamode metamaterials based on the asymmetric double-cone element (ADCE) are proposed. The ADCE is composed by two connected truncated cones with different thin diameters. The phonon band structures of the ADCEs pentamode metamaterials are numerically analysed by using the finite element method (FEM). Besides the single phonon mode, the complete 3D band gaps are also found in the phonon band structures. Here, the influence of the degree of asymmetry of ADCE to the figure of merit (FOM), which is the ratio of bulk modulus and shear modulus, is discussed. The FOM can be increased by 21–30% (at FOM ≥ 103) when the degree of asymmetry m ranges from 0.4 to 0.6.

Three–dimensional asymmetrical rolling of an aluminium flat strip using an elastic–plastic finite element method

This study developed a three–dimensional asymmetrical cold rolling finite element method for aluminium flat strips, and analysed the curved deformation of the strip caused by the difference in the rotation speed of the upper and lower rollers, and inconsistency in the radius of the upper and lower roller. As for the determination of the direction of tangential friction force, this study also developed a modification algorithm to adjust to the three–dimensional rolling process. In addition, another rule was devised to identify the neutral point to further the theoretical model develop. A comparison of the part of the computation results derived in this article and the empirical data of relevant studies shows that the finite element method developed in this article is very reasonable. The changes in the rolling force, strip curvature, strain and cross–section bulge of the various points inside a strip are further discussed under different rotation speeds and radii of the upper and lower rollers of the asymmetrical rolling.

A Phase Anti-Ambiguity Method for USBL System

Target localization was generally achieved by range and azimuth measurement for USBL (Ultra-Short Base Line) positioning system, of which the positioning accuracy was restrained by the array aperture. It usually adopted redundant array elements to solve the inconsistence between high precision and phase ambiguity. However, this routine would introduce the additional phase shift calibration problem for the complex and asymmetric array elements, which was not easy to get good results. To solve this problem, an anti-ambiguity method called dual-pulse signal is proposed in this paper to ensure the correct positioning for the improved array formation. Numerical simulations indicate that the proposed method can effectively improve the positioning precision of the USBL positioning system.

Rules relating hepatotoxicity with structural attributes of drugs

The relationship between molecular structures of drugs and their hepatotoxicity was studied by characterizing their structure in a new way and using formal concept analysis, a mathematical technique to condense knowledge into particular rules, which does not imply linearly assumptions as many conventional statistical techniques. The structural characterization was based on molecular descriptors and molecular frameworks, further decomposed into structural elements, rings, and bridges. The methodology was applied to drugs in the liver toxicity knowledge base database with the potential to cause drug-induced liver injury. Numbers of atoms and bonds along with the aromatic ratio were suitable descriptors for such drugs. The higher the number of rings and asymmetric structural elements in their terminal ring systems, the higher is the probability of hepatotoxicity. Rules were found which may help to design drugs which are unlikely to be hepatotoxic.

The Architecture and Strict-Sense Nonblocking Conditions of a New Baseline-Based Optical Switching Network Composed of Symmetrical and Asymmetrical Switching Elements

In this paper, we introduce a new multiplane optical switching fabric structure based on a baseline type switching network. The new structure is built from symmetrical and asymmetrical optical switching elements. This new architecture can be extended to structures of greater size (it means capacity as a number of inputs and outputs). To compare different types of switching architectures, we define the cost of an appropriate structure as the number of its passive and active optical elements. Generally, structure with smallest number of these elements constitutes a cheaper solution. We also introduce a strict-sense nonblocking conditions for the proposed multiplane structure and compare them with an optical baseline multiplane switching networks of the same capacity. We show that for most capacities of the switching network, the new multiplane architecture is a cheaper solution than the multiplane baseline network even when the number of planes in the new architecture is greater than the number of one planes in the baseline structure — cost of the whole new structure expressed as the number of passive and active optical elements is fewer than baseline network of the same capacity.

Biomechanical effect of graded facetectomy on asymmetrical finite element model of the lumbar spin.

Facetectomy is a leading surgical method for stenosis treatment. The objective of this study was to investigate biomechanical effect of graded facetectomy on the lumbar spine using an asymmetrical finite element model. A validated 3-dimensional asymmetrical finite element model of lumbar L1-L5 was developed based on computerized tomography (CT) scans. All components were assigned material properties mimicking original spinal components. Graded facetectomy was performed by removing facet elements along with surrounding capsular ligaments. All three planes of motion were simulated and resulting range of motion at the index level, L4-L5, was compared with the intact model. Left unilateral facetectomy caused increase in range of motion by 14.6%, 87.4%, 94.5%, 10.5%, 6.3% and 8.8% for flexion, extension, left and right axial rotation, and left and right lateral bending, respectively. Total bilateral facetectomy resulted in an increase in motion by 33.6%, 238.7%, 120.4, 151.3%, 15.6% and 12.4% for flexion, extension, left and right axial rotation, and left and right lateral bending, respectively. Extension and axial rotation were found to be affected by the facet removal whereas flexion and lateral bending were mildly affected.

Electromagnetically induced transparency and slow light in a simple complementary metamaterial constructed by two bright slot-structures

We numerically demonstrate a plasmonic analogue of electromagnetically induced transparency in a simple complementary metamaterial, the unit cell of which consists of two bright slot-structures in a homogenous gold film deposited on a glass substrate. A pronounced transparency peak within a broad reflectance resonance spectrum is activated through the coupling in the asymmetric elements when the symmetry of two slot-structures is broken. Moreover, the strength and width of the reflectance transparency peak can be tuned by controlling the asymmetric degree or spacing of two slot-structures. In addition, the presence of the reflectance transparency window is also accompanied by slow-light effect, where its group velocity is reduced by a factor of over 100. Therefore, this complementary metamaterial could have the potential applications in slow-light and filtering devices.

On the Merit of Asymmetric Phased Array Elements

Phased array antennas with a desired symmetric scan range about broadside usually are designed with array elements that have a corresponding symmetry. However, this appears to be an unnecessary restriction. We 1) show analytically that symmetric scan performance normally is maintained even with asymmetric array elements, and 2) compare conventional symmetric patch elements, which have <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$E$</tex></formula> - and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex></formula> -plane symmetry, with patches which are asymmetric in the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$E$</tex></formula> -plane, and with fully non-symmetric patches which have neither <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$E$</tex> </formula> - nor <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex> </formula> -plane symmetry. The comparison is based on patch designs obtained by numerical optimization, over a 90 degree scan volume and 3:1 bandwidth, using a genetic algorithm. The elements with spoiled symmetry clearly have better scan and/or bandwidth performance. The results support our view that spoiling the symmetry may be a general technique to improve the bandwidth of phased array elements.

Optical isotropization of anisotropic wurtzite Al-rich AlGaN via asymmetric modulation with ultrathin (GaN) m /(AlN) n superlattices

Symmetric anisotropy in wurtzite semiconductors, e.g., AlGaN, has led to the significant optical anisotropy that is rather difficult to resolve. Here, a novel scheme for achieving optical isotropization in Al-rich AlGaN through the introduction of additional asymmetric elements is demonstrated to compensate the native asymmetry. Asymmetric modulation of alloy composition and periodicity of (GaN)m/(AlN)n superlatices was proposed with first-principles simulations. Results showed that the compensation for the c-axial symmetry with the asymmetric ultrathin (GaN)m/(AlN)n superlatices (m ≤ 2) could well achieve the equivalence of the ordinary and extraordinary imaginary dielectric functions ε2 at the band edge. Measurement with spectroscopic ellipsometry for this (GaN)m/(AlN)n superlatice insertion in AlGaN host confirmed the theoretical predictions of the optical isotropization. This method can be transferred to other semiconductors in anisotropic structure and with troubles of optical anisotropy.

Asymmetric quadrilateral shell elements for finite strains

Very good results in infinitesimal and finite strain analysis of shells are achieved by combining either the enhanced-metric technique or the selective-reduced integration for the in-plane shear energy and an assumed natural strain technique (ANS) in a non-symmetric Petrov---Galerkin arrangement which complies with the patch-test. A recovery of the original Wilson incompatible mode element is shown for the trial functions in the in-plane components. As a beneficial side-effect, Newton---Raphson convergence behavior for non-linear problems is improved with respect to symmetric formulations. Transverse-shear and in-plane patch tests are satisfied while distorted-mesh accuracy is higher than with symmetric formulations. Classical test functions with assumed-metric components are required for compatibility reasons. Verification tests are performed with advantageous comparisons being observed in all of them. Applications to large displacement elasticity and finite strain plasticity are shown with both low sensitivity to mesh distortion and (relatively) high accuracy. A equilibrium-consistent (and consistently linearized) updated-Lagrangian algorithm is proposed and tested. Concerning the time-step dependency, it was found that the consistent updated-Lagrangian algorithm is nearly time-step independent and can replace the multiplicative plasticity approach if only moderate elastic strains are present, as is the case of most metals.

The Medaka zic1/zic4 Mutant Provides Molecular Insights into Teleost Caudal Fin Evolution

Teleosts have an asymmetrical caudal fin skeleton formed by the upward bending of the caudal-most portion of the body axis, the ural region. This homocercal type of caudal fin ensures powerful and complex locomotion and is regarded as one of the most important innovations for teleosts during adaptive radiation in an aquatic environment. However, the mechanisms that create asymmetric caudal fin remain largely unknown. The spontaneous medaka (teleost fish) mutant, Double anal fin (Da), exhibits a unique symmetrical caudal skeleton that resembles the diphycercal type seen in Polypterus and Coelacanth. We performed a detailed analysis of the Da mutant to obtain molecular insight into caudal fin morphogenesis. We first demonstrate that a large transposon, inserted into the enhancer region of the zic1 and zic4 genes (zic1/zic4) in Da, is associated with the mesoderm-specific loss of their transcription. We then show that zic1/zic4 are strongly expressed in the dorsal part of the ural mesenchyme and thereby induce asymmetric caudal fin development in wild-type embryos, whereas their expression is lost in Da. Comparative analysis further indicates that the dorsal mesoderm expression of zic1/zic4 is conserved in teleosts, highlighting the crucial role of zic1/zic4 in caudal fin morphogenesis.

Improving the actuating response of carbon nanotube/ionic liquid composites by the addition of conductive nanoparticles

Polyaniline (PANI) or carbon black (CB) was used as a conductive additive in porous electrodes of a dry-type carbon nanotube (CNT)-polymer actuator to improve the actuation properties. We estimated the strain from the bending motion of the actuator in the frequency range of 200–0.005 Hz. The generated stress was calculated from the Young’s modulus of the electrode film and the maximum strain. Eight different types of electrode films were prepared by changing the mixed amount of PANI or CB into the CNT electrode film. When a same amount of PANI (50 mg) against CNT (50 mg) was added to the CNT electrode (in the case of CNT/PANI(50/50)), the strain of CNT/PANI(50/50) was increased to be almost three times larger than that of CNT(50) (without any additives). As a result, CNT/PANI(50/50) showed more than five times the generated stress compared to CNT(50). Using 40 mg of CB as an additive, CNT/CB(50/40) showed a more than four times larger stress compared to CNT(50). The electrochemical properties such as conductivity and capacitance were also investigated and discussed. An asymmetrical three-layered actuator element was fabricated to investigate the actuation mechanism. The results imply that the anode contracts and the cathode expands.

Determination of crack tip parameters for ASCB specimen under mixed mode loading using finite element method

In this paper, a new asymmetric semicircular bend specimen (ASCB) is presented. Having more geometric parameters in asymmetric bend elements gives the opportunity of covering a wider range of KІ, KІІ and T-stress in comparison with classical SCB specimens. Finite element method is used to obtain these parameters from pure mode I to pure mode II. Extensive numerical calculations are made to get a wide range data for crack tip parameters of this specimen. It is observed that for ASCB specimens with specified geometries under pure mode II loading, one of the bottom supports can move horizontally without significant variation in YI. The complete sets of numerical results are obtained and can be used for verification and interpretation of future experimental results.

Wideband Dual-Frequency Dual-Polarized Dipole-Like Antenna

A wideband dual-frequency dual-polarized printed antenna is proposed for LTE, WLAN, and UWB systems. The dual-band antenna provides wide impedance bandwidths of 74% with respect to the center frequency of 2.725 GHz, and 39% with respect to the center frequency of 7.15 GHz. An open slot in the ground plane between the feed arms provides an orthogonal path to realize an embedded circularly polarized band at 2.35 GHz with an axial-ratio bandwidth of 16%. Dual-band characteristics are achieved by an asymmetrical dipole-like element and the coupling configuration between the T-shaped feed line and the wide ground-plane slot.

Diffusion on asymmetric fractal networks

We derive a renormalization method to calculate the spectral dimension d of deterministic self-similar networks with arbitrary base units and branching constants. The generality of the method allows the affect of a multitude of microstructural details to be quantitatively investigated. In addition to providing models for physical networks, the results allow precise tests of theories of diffusive transport. For example, the properties of a class of nonrecurrent trees (d > 2) with asymmetric elements and branching violate the Alexander-Orbach scaling law.

Optical bistability involving planar metamaterials with broken structural symmetry

We report on a bistable light transmission through a planar metamaterial composed of a metal pattern of weakly asymmetric elements placed on a nonlinear substrate. Such structure bears the Fano-like sharp resonance response of a trapped-mode excitation. The feedback required for bistability is provided by the coupling between the strong antiphased trapped-mode-resonance currents excited on the metal elements and the intensity of inner field in the nonlinear substrate.

Asymmetry and Symmetry in the Beauty of Human Faces

The emphasis in the published literature has mostly been on symmetry as the critical source for beauty judgment. In fact, both symmetry and asymmetry serve as highly aesthetic sources of beauty, whether the context is perceptual or conceptual. The human brain is characterized by symbolic cognition and this type of cognition facilitates a range of aesthetic reactions. For example, both art and natural scenery contain asymmetrical elements, which nevertheless render the whole effect beautiful. A further good case in point is, in fact, human faces. Normally, faces are structurally left-right symmetrical content-wise but not size-wise or function-wise. Attractiveness has often been discussed in terms of content-wise full-face symmetry. To test whether or not attractiveness can be gleaned only from the presence of left-right full-faces we tested half faces. Three separate groups of participants viewed and rated the attractiveness of 56 full-faces (women’s and men’s), their 56 vertical left hemi-faces and 56 vertical right hemi-faces. We found no statistically significant differences in the attractiveness ratings of full- and hemi-faces (whether left or right). Instead, we found a strong and significant positive correlation between the ratings of the hemi- and full-faces. These results are consistent with the view that the underpinning of human facial beauty is complex and that bilateral symmetry does not constitute a principle factor in beauty assessment. We discuss that the highly evolved human brain, compared to other animals, as well as symbolic and abstract cognition in humans enable a wide variety of aesthetic reactions.

Polarized infrared emission using frequency selective surfaces

An emission frequency selective surface, or eFSS, is made up of a periodic arrangement of resonant antenna structures above a ground plane. By exploiting the coupling and symmetry properties of an eFSS, it is possible to introduce polarization sensitive thermal emission and, subsequently, coherent emission. Two surfaces are considered: a linearly polarized emission surface and a circularly polarized emission surface. The linearly polarized surface consisted of an array of dipole elements and measurements demonstrate these surfaces can be fabricated into high polarization contrast patterns. The circularly polarized surface required the use of an asymmetrical tripole element to maintain coherence between orthogonal current modes and introduce the necessary phase delay to realize circularly polarized radiation.

The chiral Gaussian two-matrix ensemble of real asymmetric matrices

We solve a family of Gaussian two-matrix models with rectangular N × (N + ν) matrices, having real asymmetric matrix elements and depending on a non-Hermiticity parameter μ. Our model can be thought of as the chiral extension of the real Ginibre ensemble, relevant for Dirac operators in the same symmetry class. It has the property that its eigenvalues are either real, purely imaginary or come in complex conjugate eigenvalue pairs. The eigenvalue joint probability distribution for our model is explicitly computed, leading to a non-Gaussian distribution including K-Bessel functions. All n-point density correlation functions are expressed for finite N in terms of a Pfaffian form. This contains a kernel involving Laguerre polynomials in the complex plane as a building block which was previously computed by the authors. This kernel can be expressed in terms of the kernel for complex non-Hermitian matrices, generalizing the known relation among ensembles of Hermitian random matrices. Compact expressions are given for the density at finite N as an example, as well as its microscopic large-N limits at the origin for fixed ν at strong and weak non-Hermiticity.