Elliptical Hollow Research Articles

Propagation of elliptical Gaussian vortex beam based on angular spectrum representation

Vortex beams with hollow elliptical ring structure have attracted broad interest in applications such as micro-particle trapping and manipulation. The paper investigates the dependence of the hollow elliptic ring structure of vortex beams on the beam order and the topological charge, while propagating in the near- and far-field zones. The electric field of the beam is formulated by using the angular spectrum method, which satisfies rigorously Maxwell's equation. The electric field, linear momentum and orbital angular momentum are calculated. Numerical results show that the hollow elliptical ring structure approximately remains unchanged over a finite propagation distance, accompanied by a rotation whose angle depends on the topological charge. In the far-field zone, the ring structure is broken, leading to two bright spots and several dark islands. It is found that the beam profile in the near-field zone is mainly related to the beam order but in the far-field zone is primarily affected by the topological charge. The results presented in the paper may be useful in predicting and explaining the interaction between the elliptic hollow Gaussian vortex beam and the micro-particles, such as the movement of micro-particles along the orbit and the rolling rotation.

Optical communications with guided wave fibers with rectangular cladding for fuel adulteration detection

Abstract Fuel quality has a significant impact on the lifespan and smooth operation of petroleum engines. Many dishonest merchants mix lower priced oil/ingredients with petroleum products to increase their profit. To solve this problem, a terahertz waveguide-based fuel adulteration sensor that can detect the presence of kerosene in gasoline is proposed. The design procedure is performed by large elliptical hollow core photonic crystal fiber including rectangular cladding. In our study, the used sensor’s performance is investigated and FEM is also used for performing numerical analysis. Our used sensor achieved a maximum 80.34% sensitivity with a negligible total loss having 3.74 × 10−2 cm−1 during 2.8 THz optimum operating frequency conditions which are very impressive. Additionally, under ideal circumstances, the used sensor attained a sound birefringence of 0.01 and 0.034 ranging numerical aperture. The proposed sensor’s structure is quite simple which might make the fabrication process easy. Furthermore, because of the higher sensitivity and guiding properties, the sensor will be an important part of real-life applications in the forthcoming years.

Spiraling elliptic hollow beams with cross phase

We introduced a class of spiraling elliptic hollow beams with the cross phase. Due to the cross phase, the spiraling elliptic hollow beams exhibit three key characteristics, having the elliptic peak ring, carrying the orbital angular momentum (OAM), and performing rotations. We investigated both linear and nonlinear evolutions of the spiraling elliptic hollow beams, and found they can propagate stably, thanks to the cross phase. Especially, we obtained the breather states of spiraling elliptic hollow beams in nonlocally nonlinear medium, and could handily control the rotation by changing optical powers. We discussed both the OAM property and optical force property. By using the spiraling elliptic hollow beams, we can achieve a jointly multiple manipulation on particles at the same time. In one step, we can trap and simultaneously rotate the particles.

A D-shaped elliptical hollow core fiber SPR sensor

A D-shaped elliptical hollow core fiber surface plasmon resonance (SPR) sensor is proposed and analyzed here using gold and titanium oxide (TiO2) layer. The fiber geometry consists of a doped elliptical core with a concentric central elliptical air hole. A finite element method-based simulation software COMSOL Multiphysics is used for numerical analysis. Both gold and TiO2 layers are optimized. The sensor responds over a wide range of refractive index (RI) from 1.33 to 1.40. The average sensitivity obtained for the designed sensor is 4142.85nm/RIU (RI Unit) whereas that for a single mode fiber (SMF) is only 897.55nm/RIU. So, our designed sensor gives more than 4 times enhanced sensitivity and proves to be a potential alternative of SMF based low cost, compatible SPR sensors by covering the low sensitivity issue suffered by SMF sensors.

Exploring the ellipticity dependency on vector helical Ince-Gaussian beams and their focusing properties.

We present a numerical study of the intensity and polarization structure of vector helical Ince-Gaussian (VHIG) modes, which present a distinct subclass of vector Ince-Gaussian modes with defined parameter settings. The intensity profile of VHIG beams has an elliptic hollow structure, while the polarization distribution shows multiple single-charge polarization vortices arranged along a line. By selecting the mode order, phase factor and ellipticity of the VHIG beams, we can control the number of elliptic rings, the number of polarization vortices, and the topology of the vector singularity. Furthermore, we simulate the focusing properties of VHIG beams based on vector diffraction theory. Our results indicate that the ellipticity parameter of VHIG beams could be a valuable degree of freedom to generate attractive transverse profiles and longitudinal distributions under focusing, which may have implications for lithography, material processing, optical communication, and even optical trapping and manipulation.

Lateral Impact Response of Elliptical Hollow and Partially Concrete-Filled Cold-Formed Steel Columns Under Static Axial Compression Load

In recent years, the use of partially concrete-filled steel tubular (PCFST) columns has been considered due to their cost-effectiveness and reduction of structural weight in bridge piers and building columns. One of the critical discussions about these columns is their impact resistance. In this article, the dynamic response of hollow and PCFST columns with elliptical cross-section under simultaneous loading of static axial compressive load and lateral impact load is presented using finite element modeling in ABAQUS software (FEA). To ensure the accuracy of the numerical modeling, the analysis results are compared with the results of previous works. The effects of different parameters such as impact velocity, the height of the impact location, the impact direction, the impact block mass, the size and shape of the impact block are investigated in this paper. The results of the numerical analysis showed that the partially filled specimens had better performance than the hollow specimens. The changes in impact direction and impact block mass parameters have a significant effect on the failure of the columns, especially when they are under high impact velocity. Changing the impact velocity significantly affects the impact resistance of specimens. However, the size and shape of the impact block did not have a significant effect on the displacement of the column against the impact loading.

Fire resistance of stainless steel slender elliptical hollow section beam-columns

PurposeStainless steel has different advantages when compared to conventional carbon steel. The corrosion resistance and aesthetic appearance are the most known; however, its better behaviour under elevated temperatures can also be important in buildings design. In spite of the initial cost, stainless-steel application as a structural material has been increasing. Elliptical hollow sections integrate the architectural attributes of the circular hollow sections and the structural advantages of the rectangular hollow sections (RHSs). Hence, the application of stainless-steel material combined with elliptical hollow profiles stands as an interesting design option. The purpose of the paper is to better understand the resistance of stainless-steel-beam columns in case of fireDesign/methodology/approachThe research presents a numerical study on the behaviour of stainless-steel members with slender elliptical hollow section (EHS) subjected to axial compression and bending about the strong axis at elevated temperatures. A parametric numerical study is presented here considering with and without out-of-plane buckling different stainless-steel grades, cross-section and member slenderness, bending moment diagrams and elevated temperatures.FindingsThe tested design methodologies proved to be inadequate for the EHS members being in some situations too conservative.Originality/valueThe safety and accuracy of Eurocode 3 (EC3) design methodology and of a recent design proposal developed for I-sections and cold-formed RHSs are analysed applying material and geometric non-linear analysis considering imperfections with the finite element software SAFIR.

Design of stainless steel elliptical hollow sections columns in case of fire: parametric study

AbstractThe application of stainless steel as a structural material has been increasing, due to a number of desirable qualities such as its durability, resistance to corrosion and aesthetic appearance. Since it has a higher fire resistance when compared to carbon steel, it allows in some cases the absence of thermal protection. In addition to the aesthetic nature, elliptical hollow sections integrate the architectural attributes of the circular hollow sections and the structural advantages of the rectangular hollow sections. They have a better torsional behaviour than open sections and due to their shape they have a higher bending strength when compared to circular hollow profiles. Hence, the application of the material stainless steel combined with elliptical hollow sections stands as an interesting design option. The main objective of this study is to perform a parametric study to understand the fire behaviour of stainless steel columns subjected to axial compression, with Elliptical Hollow Sections and to analyse the safety and accuracy of the Eurocode 3 design methodology for these members. From comparing the obtained ultimate load bearing capacities with Eurocode 3 prescriptions, it is concluded that this design methodology is not suitable for this type of cross‐section profiles.

Generation of diffraction-free vectorial elliptic hollow beams with space-varying inhomogeneous polarizations* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11304093 and 11274114), the Hubei Provincial Natural Science Foundation, China (Grant No. 2018CFB320), and the Academic Discipline Project of Hubei Normal University, China (Grant Nos. 2014F012 and 2014F013).

Diffraction-free vectorial elliptic hollow beams (vEHBs) are generated by an optical system composed of a short elliptic hollow fiber (EHF) and an axicon. Each beam has a closed elliptic annular intensity profile and space-varying polarization states in its diffraction-free distance of more than 1 m. The generated beams have a counter-clockwise or clockwise periodically-rotated inhomogeneous polarization. And the spin angular momentum (SAM) of the vEHBs is 1ℏ or –1ℏ which is consistent with the type of dual-mode in the EHF and the periodic polarization rotations of the vEHBs. The vEHBs have potential applications in optically trapping and micromanipulating the micro- or nano-particles, quantum information transmission, and Bose–Einstein condensates, etc.

Simple birefringent Terahertz fiber based on elliptical hollow core

Abstract In this paper, a simple birefringent Terahertz fiber based on elliptical hollow core is proposed which is easy to be fabricated by 3D printer. The birefringence of the proposed fiber is obtained by the difference in resonance frequency of two polarization modes caused by structural asymmetry which is not similar to that caused by a simple asymmetric structure. A modal birefringence of the order of 10−3 is obtained with the loss of 0.005 cm−1. The sample is measured experimental. The experimental results are consistent well with the simulation results. And a fast light phenomenon was found during the measurement of the sample.

Düzlem İçi Eğilme Momenti Altındaki Elips Enkesitli T-birleşimlerinin Dayanımları

Elliptical Hollow Sections (EHS) have become popular in recent years due to their aesthetic and elegant appearance. Apart from its architectural advantages, it has many advantages in terms of engineering. However, there is no design guide for the design of the joints made of EHS. In the structural applications, equivalent box profile approach is generally used. Since the EHSs have two different diameters, the joint can be formed by four different orientations. Therefore, the equivalent box profile approach may not always yield economic and safe results.

Coupling characteristics and kurtosis parameter of partially coherent beams in turbulent atmosphere

ABSTRACTCoupling properties and kurtosis parameter (K parameter) of arbitrary beams propagating through atmospheric turbulence are investigated. A correlation factor (C4-factor) is introduced to describe the influence of turbulence on coupling characteristics. The general analytical expression for C4-factor of arbitrary beams in atmospheric turbulence is derived. It is shown that C4-factor of arbitrary beams in the turbulent atmosphere depends on the initial second-order moments and fourth-order moments and turbulence quantities. Taking the partially coherent anomalous elliptical hollow Gaussian (PCAEHG) beam as an example, we can obtain that C4-factor decreases as structure constant of the refractive index fluctuations and inner scale increase, and waist width and transverse coherence length decrease when z > 5 km. Moreover, K parameter of PCAEHG beam in turbulent atmosphere converges to 2 when propagation distance is large enough. It indicates that the profile of PCAEHG beams in turbulent atmosphere finally evolves into fundamental Gaussian distribution.

Study on the Influence of Two Relativistic Circular Electron Beam Columns Placed in an Elliptical Dielectric Waveguide on Excitation and Amplification of Electromagnetic Waves Using Finite-Element Method

In this paper, the finite-element method (FEM) is applied for an exact solution of the dispersion of hybrid electromagnetic waves excited in a novel combined elliptical waveguide. This special configuration is included of an elliptical metallic waveguide filled with a dielectric material, whereas two axial hollows with circular cross section have been created in it. A hollow is placed in one of focuses of the elliptical waveguide and second hollow is located in another focus or shifted from it. Two straight relativistic electron beams with the same currents and velocities in opposite directions are injected inside the hollows. Here, we apply an accurate approach in which the electromagnetic fields described by the FEM and satisfies boundary conditions at the interfaces of different regions. Then, the time growth rate of slow waves amplified by the electron beam is numerically calculated. The excited waves are in microwave range. The effects of accelerating voltage and current density of electron beams, and geometrical parameters such as radius and location of electron beam, on the frequency spectra, the growth rate, and profiles of axial electric and magnetic fields of excited slow waves are studied. Our research shows, the novel waveguide studied in this paper is superior to other waveguide structures in wave amplification with applying minimum input electrical power.

A study of electromagnetic free forming in AA5052 using digital image correlation method and FE analysis

Electromagnetic forming (EMF) is a promising process that can improve the forming limit under room temperature. In this work, AA5052 sheets were electromagnetic free formed at various discharging energies with an elliptic spiral coil and an elliptical hollow die. Two high-speed cameras with a certain angle to each other photographed the entire deformation process. Full-field displacement, velocity, strain and strain rate were calculated by a digital image correlation (DIC) system. The sheets were deformed into oval domes and the peak strain rate measured was about 12,400 s-1. A 3D numerical model was established using the method of combing Finite Analysis (FEA) and Boundary Element Method (BEM). The simulation results were in good agreement with the experiments. Sheet deformation at the center region had a significant delay relative to the periphery region, and the velocity curves could be divided into three stages: initial increase, speed sustention and second-time increase. Several microscopic test regions with same final equivalent strain but different strain histories were confirmed by DIC technology and FEA/BEM model. Different strain histories would affect grain distribution and local hardness.

Performance of Elliptical Hollow Sections under Combined Compression and Cyclic Bending

AbstractThis paper comprehensively discusses the potential of applying elliptical hollow sections (EHSs) for seismic regions. The study commenced with an experimental investigation of 12 EHS beam-c...

Axicon aberration leading to short-range nondiverging optical array and elliptical dark hollow beam

We propose a unique method for producing nondiverging optical array and elliptical hollow beam in a controlled manner using aberration patterns generated from oblique illumination of axicon. The optical arrays with propagation invariance property are persisted for short ranges in the focal depth, whereas diverging array with a constant number of bright spots is produced beyond bottle beam. The measured variation in the geometrical parameters of obliquely illuminated axicon setup has facilitated precise control on the dimension of optical array and shape of the elliptical hollow beam, respectively. The theoretical analysis confirms the experimental results for the generation of short-range nondiverging optical array and elliptical dark hollow beam with fine control. To the best of our knowledge, this is the first experimental approach to extend the potential of axicon beyond generation of Bessel and circular hollow beams.

YANGINDA ELİPS ENKESİTLİ KOLONLARIN DAVRANIŞI

This paper presents the results of a numerical study to understand the behavior of Elliptical Hollow Section (EHS) columns at elevated temperatures. A large number of numerical studies have been carried out using the non-linear finite element software ABAQUS v6.14-1 to investigate the influence of slenderness, initial applied load level and axial restraint stiffness on the fire resistance of EHS steel columns at high temperatures. The uniform temperature distribution is assumed. The Finite Element simulation results have been compared with the calculation results using the Eurocode EN 1993-1-1 and Turkish design guide equations in order to check whether the current design method is safe or not. It has been found that the current method for calculating critical temperatures of axially restrained EHS steel column is unsafe. Therefore, a new simple design method has been introduced.

A novel plasmonic elliptical nanocluster and investigating Fano response in π- and T-shaped arrays

ABSTRACTFano resonance has been considered especially in nanostructures for energy enhancement and creating hot spots in nanoparticles based on plasmonic properties. In this paper, a novel arrangement of elliptical nanoantenna has been noticed for improving the electric field and energy enhancement in hot spots for mid-infrared range. For this, elliptical cylinders and elliptical rings are developed for dark mode by the concentration of plasmonic charges in a limited area, and the interaction between bright and dark mode has been used for the Fano shape of the extinction cross section. The combination of dipole arrangement has been implemented based on elliptical hollow cylindrical particles with various inner radios for arousing the Fano resonance. Finally, π- and T-shaped models are studied for Fano resonance, and the electric fields are compared in all cases. Exactly, this study is important for two main reasons: (1) it shows how we can control the extinction cross section and (2) it shows that by distortion for linear array the Lorentzian shape is changed to Fano shape.

Effect of outer membrane vesicles derived from Escherichia coli on proliferation, apoptosis and migration of human neuroblastoma SK-N-SH cells in vitro

To investigate the effect of outer membrane vesicles derived from Escherichia coli on proliferation, apoptosis and migration of human neuroblastoma SK-N-SH cells in vitro. The outer membrane vesicles (OMVs) were obtained from wild-type Escherichia coli with ultracentrifugation method, and the morphology of the OMVs was observed by transmission electron microscopy and the vesicle diameter was determined using MALVERN ZEN3690. Human neuroblastoma SK-N-SH cells were treated with the OMVs at low (100 µg/mL), moderate (500 µg/mL) and high (1000 µg/mL) doses, and 24, 48 and 72 h later, the cell proliferation activity was detected with MTT assay. The expressions of apoptosis-related marker caspase-3 was detected using Western blotting, and TUNEL assay was performed to detect the cell apoptosis. The migration capacity of SK-N-SH cells was evaluated using Transwell migration assay. The isolated OMVs showed a circular or elliptical hollow structure with double-layer membrane and a diameter range of 30-450 nm. Compared with the control cells, SK-N-SH cells treated with the OMVs showed significantly lowered cell proliferation capacity with enhanced expression of caspase-3. Treatment of the cells with the OMVs resulted in increased cell apoptosis and significantly lowered migration capacity (P<0.05). The OMVs derived from Escherichia coli can produce cytotoxicity against SK-N-SH cells and might serve as a therapeutic agent for refractory neuroblastoma.

Behavior of Concrete-Filled Circular, Square, Rectangular, and Elliptical Hollow Columns Subjected to Fire

AbstractThis paper presents and discusses the results of experiments on the behavior of composite columns made of concrete-filled hollow sections subjected to fire and restrained thermal elongation...