Conical Pattern Research Articles

Hydrothermal behaviour of hybrid nanofluid flow in a shell-and conical coil tube heat exchanger; numerical approach

The present work considers a shell-and-coil heat exchanger, and the hybrid nanofluid's flow and heat transfer inside the proposed thermal system are numerically evaluated. The coil tube has a conical pattern and is oriented horizontally inside the shell. Three water-based hybrid nanofluids are considered here as heat transfer fluids. A commercial CFD code that uses the finite volume method performs the numerical analysis. The regime of fluid flow is turbulent in both coil and shell sections. The validation analysis of the present numerical model was performed using the experimental results of the reference, and accordingly, the accuracy of the present numerical model was proved. This work includes two sectors. In the first part, the volume concentration of the considered hybrid nanofluid was kept constant, and the influence of the hybrid nanofluid kind on the hydrothermal behaviour of the shell-conical-coil heat exchanger was evaluated numerically. In this section, three hybrid nanofluids, (i) Water/MgO–TiO2, (ii) Water/MOS2-CuO, and (iii) Water/Ag-HEG, were employed. Also, for all suggested hybrid nanofluids, the volume concentration of both employed nanoparticles are equal to each other, φ1 = φ2. The obtained outcomes depicted that between various considered heat transfer fluids, the Water/MgO–TiO2 model displayed the most outstanding thermal performance value in all the investigated Dean numbers, and the model Water/MOS2-CuO was in second place. Moreover, the maximum thermal performance for the hybrid nanofluid was obtained at φ1 = φ2 = 0.7. The Ag-HEG/Water and MgO–TiO2/Water hybrid nanofluids have the lowest and maximum thermal performance at the lowest considered Dean number among the evaluated hybrid nanofluids. As a result, the MgO–TiO2/Water hybrid nanofluid has roughly 18.95 % higher thermal performance than the Ag-HEG/Water hybrid nanofluid. Furthermore, the MgO–TiO2/Water and Ag-HEG/Water hybrid nanofluids have the highest and lowest thermal performance at the highest considered Dean number, respectively. Consequently, the MgO–TiO2/Water hybrid nanofluid exhibits approximately 39.22 % higher thermal performance than the Ag-HEG/Water hybrid nanofluid. The MgO–TiO2/Water hybrid nanofluid has the highest and lowest thermal performance at the lowest Dean number, with φ1 = φ2 = 0.7 and φ1 = φ2 = 0.3, respectively. The φ1 = φ2 = 0.7 model has a thermal performance that is approximately 39.28 % greater than the φ1 = φ2 = 0.3 model at the lowest regarded Dean number. At the highest regarded Dean number, the MgO–TiO2/Water hybrid nanofluid with φ1 = φ2 = 0.3 exhibits a lower thermal performance than the model φ1 = φ2 = 0.7 by about 14.28 %.

Wide-angle scanning and Wideband millimeter-wave phased array with Enhanced Isolation using Novel Triple-function Electric Walls

A wide-angle scanning millimeter-wave (mm-wave) phased array with enhanced bandwidth and isolation using novel triple-function electric walls (TEWs) is presented in this work. First, a novel concept for element beamwidth broadening is proposed by using a suspended horizontal magnetic current (SHMC) with a conical pattern. Then, based on this concept, an antenna element is designed using the proposed TEWs. TEWs not only broaden the element beamwidth by forming a suspended horizontal magnetic current(SHMC), but also widen the element bandwidth by introducing a new mode. Meanwhile, the proposed TEWs can be used as a band-stop filter in the array to reduce the mutual coupling. Based on the three beneficial functions of the proposed TEWs, a wide-angle scanning mm wave phased array with enhanced bandwidth and isolation is designed. Measured results show that the phased array achieves an active impedance bandwidth of 19.3% (24.7-30 GHz) and a good isolation of more than 15 dB. Meanwhile, a wide 3 dB scanning angle larger than ±74° is achieved by the proposed array with the maximum scanning angle of ±80° at 27 GHz.

An easy-to-produce HIS-based MIMO radio altimeter antenna design for aircraft

Purpose The purpose of this study is to design a radio altimeter antenna whose production process is facilitated and can work with multiple-input multiple-output (MIMO) properties to provide space gain on the aircraft. Design/methodology/approach To create an easy-to-produce MIMO, a two-storied structure consisting of a reflector and a top antenna was designed. The dimensions of the reflector were prevented to get smaller to supply easy production. The unit cell nearly with the same dimensions of a lower frequency was protected through the original cell design. The co-planar structure with the use of a via connection was modified and a structure was achieved with no need to via for easy production, too. Finally, the antennas were placed side by side and the distance between them was optimized to achieve a MIMO operation. Findings As a result, an easy-to-produce, compact and successful radio altimeter antenna was obtained with high antenna parameters such as 10.14 dBi gain and 10.55 dBi directivity, and the conical pattern along with proper MIMO features, through original reflector surface and top antenna system. Originality/value Since radio altimeter antennas require high radiation properties, the microstrip antenna structure is generally used in literature. This paper contributes by presenting the radio altimeter application with antenna-reflective structure participation. The technical solutions were developed during the design, focusing on an easy manufacturing process for both the reflective surface and the upper antenna. Also, the combination of International Telecommunication Union’s recommended features that require high antenna properties was achieved, which is challenging to reach. In addition, by operating the antenna as a successful MIMO, two goals of easy production and space gain on aircraft have been attained at the same time.

Realization of circular polarized multiple band multi-mode OAM antenna using a ring patch for IoT applications

A multiband and multi-mode antenna with circular polarized conical patterns is suitable for achieving desired spectral efficiency, increased capacity, and spatial diversity for IoT applications. However, simultaneous excitation of such circular polarized multiple Orbital Angular Momentum (OAM) modes through a single patch antenna is challenging due to the complexity of simultaneously fulfilling distinct requirements of each mode. In this paper, a ring patch antenna is designed to excite different OAM states at different frequencies simultaneously. First, characteristic mode analysis is used to analyze the possibility of simultaneous excitation of multiple OAM modes at corresponding frequencies through a simple ring patch antenna. Then, a dual port ring patch antenna is designed and fabricated to verify the capability of generating multiple OAM states at corresponding frequencies. Furthermore, it also presents the guidance to suppress unwanted OAM modes.

A shared aperture antenna with reconfigurable pattern by common and differential modes

AbstractIn this letter, a compact pattern‐reconfigurable (PR) antenna for indoor communication is proposed, which can provide one conical, one broadside, and two tilted patterns. The proposed antenna comprises a shared radiation patch with two highly isolated ports and a reconfigurable feeding network. By activating each port independently, a dipole mode with broadside pattern and a monopole mode with conical pattern are acquired, respectively. Meanwhile, inspired by the theory of common and differential modes, two tilted patterns toward and are realized by combining dipole and monopole modes. As a result, four‐type reconfigurable patterns can be obtained. To realize reconfigurability, a functional reconfigurable feeding network is designed with innovation. The proposed antenna is fabricated and measured. The measured overlapped −10 dB impedance bandwidth is 3.28–3.71 GHz (12.3%), and the peak radiation efficiency is superior to 82.7%. The experimental results indicate that the proposed PR antenna has a wide bandwidth and stable radiation patterns, which exhibits attractive potential for fifth‐generation indoor communication in sub‐6 GHz.

Broadband inhomogeneous lens with conical radiation pattern

This manuscript presents a lens antenna with simultaneous broadside and conical beams. The lens is designed for the Ku band using the ray inserting method. The proposed conical radiation pattern is broadband due to good matching with the source and surroundings. The simulation is conducted using the CST microwave studio solver. Instead of complex antenna shapes used in other works, a simple circular patch ring and RF connector are used as the lens feed to generate broadside and omnidirectional conical patterns, respectively. To validate the performance of the designed lens and its two-port feed antenna, the lens structure is realized and fabricated using the 3D printing method. Polyethylene terephthalate glycol (PETG) plastic material is utilized for constructing the lens in this work. The electromagnetic characteristics of PETG in the Ku band are accurately measured. The results of simulations and experiments demonstrate the good performance of the designed lens over a wide frequency bandwidth. The advantage of this designed structure over other works is its high gain and broad bandwidth.

Experimental verification of the bistable behavior of conical Kresling origami

Origami-inspired structures have attracted various multidisciplinary applications in the field of science and technology. Among these, the classical Kresling origami pattern has been widely exploited for its bistable behavior. However, the experimental investigation and verification of the bistability phenomenon of non-prismatic Kresling origami pattern has not been presented in the literature. This study focuses on the mathematical and experimental investigations of the bistable behavior of the conical Kresling pattern. The paper utilizes a mathematical investigation based on the energy approach to develop qualitative and quantitative stability maps for conical Kresling structures while considering the conicity of the structure with respective design parameters of the conical Kresling pattern. A systematic experimental methodology is introduced to investigate the quasistatic behavior of conical Kresling structures under applied vertical displacement, followed by the experimental characterization of the restoring force behavior considering different design parameters. Moreover, the bistability points obtained from experimental investigations are verified with mathematically developed bistability maps.

Generation of Periodic Nondiffractive Beams Along Straight and Curved Trajectories Based on 3-D-Printed Metasurface

In this paper, two kinds of periodic nondiffractive beams along arbitrary trajectories, including non-accelerating and self-acceleration types, are generated by 3D-printed all-dielectric metasurfaces. The first step is to produce continuous non-accelerating and self-acceleration beams, i.e. Bessel beam and Bessel-like beams. By an appropriate modification of the conical ray pattern of the standard Bessel beams, self-accelerating Bessel-like beams can be realized. In the second step, by removing some expanding phase equivalent circles in a periodic fashion and binary modulating of the phase masks, the central main lobe of continuous beams can be modified into pulsating ones. In the third step, we construct real physical models based on the derived theories. All phase coverage can be achieved by changing the height of the proposed cube element. Therefore, the final phase distribution can be mapped to height information of each unit cell. For demonstration, several proof-of-principle metasurfaces are printed and measured, two of which are used to generate Bessel beams along different straight directions, and two of which are used to produce Bessel-like beams along C-shaped and S-shaped trajectories. In all cases, during propagation, the intensity peak alternately switches its position between the main lobe and the outing rings. Meanwhile, the measured trajectories are highly consistent with the predefined ones. The proposed metasurfaces are expected to be utilized in numerous applications like secure communication.

Design and Kinematics of Origami Inspired Non-Prismatic Foldable Truss Modules

Abstract Origami inspired deployable structures have received significant attention due to their exceptional kinematic and mechanical characteristics. Specifically, the cylindrical Kresling origami pattern has been extensively investigated for its multi-stable properties in past studies. This study presents the design and analysis of a novel non-prismatic foldable/deployable truss module inspired from the conical Kresling origami pattern. The intrinsic relationship between the kinematics and mechanics of non-prismatic foldable truss (NPFT) modules is investigated. First, the geometric design and the analytical modeling of the motion behavior of NPFT modules are presented, followed by the development of design maps considering a range of design parameters to demarcate the domains of qualitatively different deployment behavior. The numerical simulations were performed to validate the findings of analytical investigations. Later, the comparative analysis is presented to highlight the advancements of the proposed NPFT modules over conical Kresling truss structures. The programability of the deployment characteristics of NPFT modules is investigated considering different design parameters and the influence of scaling. The outcomes demonstrate that the proposed design of NPFT modules offers enhanced deployable and tunable properties along with ease of manufacturing for reconfigurable truss structures.

Frequency-resolved characterization of broadband two-color air-plasma terahertz beam profiles.

The frequency-resolved terahertz (THz) beam profile characteristics of a two-color air-plasma THz source were investigated in the broadband frequency range (1-15 THz). The frequency resolution is achieved by combining THz waveform measurements and the knife-edge technique. Our results show that the THz focal spot size is strongly frequency dependent. This has important implications on nonlinear THz spectroscopy applications where accurate knowledge of the applied THz electrical field strength onto the sample is important. In addition, the transition between the solid and hollow beam profile of the air-plasma THz beam was carefully identified. Far from the focus, the features across the 1-15 THz range have also been carefully examined, revealing the characteristic conical emission patterns at all frequencies.

Effects of gas inlet orientation on discharge characteristics of coaxial dual-channel cross-field atmospheric plasma jet

In this paper, the effect of the gas inlet orientation on the discharge characteristics of the coaxial dual-channel cross-field plasma jet is investigated. A working gas helium is separately flowed into the annular space between the hollow needle tube and the quartz tube (called Q-Jet), as well as the hollow needle tube (called N-Jet). With the same discharge parameters, the results show that the radial and axial dimensions of Q-Jet plasma jet are larger than that of N-Jet. Compared with the latter, the discharge current amplitude of the former increases by about 3.8-fold, the net charge transferred increases by about 8.8-fold, and the variety and density of reactive species produced are remarkably increased. For Q-Jet, the 706-nm spectral band is distributed inside and outside the quartz tube, while the 391-nm spectral band is mainly distributed outside the quartz tube, and the plasma jet forms a conical luminous pattern in the quartz tube during the positive half cycle of the voltage, due to the influence of helium viscosity. For N-Jet, 706- and 391-nm spectral bands are only just distributed in the axis of the quartz tube, and the charges left by the first discharge in the axial position of the quartz tube remarkably amplify the intensity of the second discharge in the positive half cycle.

Cactus-Inspired Photonic Crystal Chip for Attomolar Fluorescence Multi-analysis.

Automation and efficiency requirements of environmental monitoring are the pursuit of spontaneous sampling and ultrasensitivity for current sensory systems or detection apparatuses. In this work, inspired by cactus hierarchical structures, we develop a cactus-inspired photonic crystal chip to integrate spontaneous droplet sampling and fluorescence enhancement for sensitive multi-analyte detection. A conical hydrophilic pattern on hydrophobic surfaces can give rise to unidirectional Laplace pressure, which drives droplet transport to the assigned photonic crystal site. The nanostructure of photonic crystals has bigger capillarity to drive the droplet wetting uniformly into the photonic crystal matrix while performing prominent fluorescence enhancement by their photonic bandgap. A low to attomolar (2.24 × 10-19 M) fluorescence limit of detection (LOD) sensitivity can be achieved by the synergy of spontaneous droplet sampling and fluorescence enhancement. Focused on eutrophic water problems and algae pollution monitoring, a femtomolar (1.83 × 10-15 M) LOD and identification of various microcystins in urban environmental water can be achieved. The suitable integration of the unidirectional droplet transport by Laplace pressure and fluorescence enhancement by photonic crystals can achieve the spontaneous sampling and signal enhancement for ultratrace detections and sample survey of environmental monitoring and disease diagnosis.

Gunshots through laminated glass: expelled compounded fragments as a function of bullet type

In the frame of an experimental setting, the formation of round-shaped compounded glass fragments on the exit site after gunshots through a windshield was examined. For that purpose, a 9 × 19 mm pistol (HK P30) and two different cartridges containing (a) a full metal jacketed round-nosed projectile and (b) a deformation projectile were used. On the basis of 52 gunshots, the morphology, impact angles and terminal ballistics of occurring compounded glass fragments were examined. The results showed that the compounded glass fragments’ morphology allowed for the differentiation of two used projectiles. Fragments were able to cause round-shaped defects in a single cotton layer (T-shirt) with subsequent penetration of up to 2.4 cm into ballistic gelatin (10%, 4 °C). As a function of the projectile type, the compounded glass fragments showed different reproducible impact angles that differed notably from the known conical pattern of expelled glass fragments after bullet penetration. These findings might help to explain the atypical morphology of gunshot wounds with laminated glass as an intermediate target and prevent possible misinterpretations when reconstructing the sequence of events.

Pore-scale study of mineral dissolution in heterogeneous structures and deep learning prediction of permeability

Reactive transport processes in porous media with dissolution of solid structures are widely encountered in scientific and engineering problems. In the present work, the reactive transport processes in heterogeneous porous structures generated by Monte Carlo stochastic movement are simulated by using the lattice Boltzmann method. Six dissolution patterns are identified under different Peclet and Damkohler numbers, including uniform pattern, hybrid pattern, compact pattern, conical pattern, dominant pattern, and ramified pattern. Particularly, when Peclet and Damkohler numbers are larger than 1, the increase in the heterogeneity rises the chance of preferential channel flow in the porous medium and thus intensifies the wormhole phenomena, leading to higher permeability. The pore-scale results also show that compared with the specific surface area, the permeability is more sensitive to the alteration of the structural heterogeneity, and it is challenging to propose a general formula between permeability and porosity under different reactive transport conditions and structural heterogeneity. Thus, deep neural network is employed to predict the permeability–porosity relationship. The average value of mean absolute percentage error of prediction of 12 additional permeability–porosity curves is 6.89%, indicating the promising potential of using deep learning for predicting the complicated variations of permeability in heterogeneous porous media with dissolution of solid structures.

Modal Analysis, Inverse-Design, and Experimental Validation of Bandwidth-Controllable Suspended Patch Antennas Loaded With Cylindrical Anisotropic Impedance Surfaces

In this article, bandwidth-controllable suspended patch antennas (SPAs) loaded by anisotropic impedance surfaces (AISs) are proposed. A highly efficient yet accurate semianalytical modal expansion method (MEM) is developed for calculating the input impedance and radiation properties of the proposed antenna, which greatly reduces the simulation time and consumed memory compared to a commercial full-wave solver. The MEM is further utilized by coupling it with a genetic algorithm for effectively performing inverse-design, i.e., optimizing AIS-loaded SPAs with different predefined frequency responses. Three proof-of-concept antenna examples are designed, fabricated, and characterized, including an ultrawideband (UWB) antenna, a dual-wideband antenna, and a band-notched UWB antenna. The operating principle is illustrated by investigating the resonant modes of the AIS-loaded SPAs. The measured results of the three antennas exhibit good agreement with theoretical predictions, demonstrating that all three antennas have vertically polarized conical patterns in the E-plane and omnidirectional patterns in the H-plane with a cross polarization of smaller than −15 dB in their respective operational frequency band(s). The good performance demonstrates that the proposed AIS-loaded SPAs are promising candidates for broadband and multiband communications.

A Compact Wideband Pattern Diversity Antenna for 5G-NR Applications

In this letter, a novel compact wideband antenna with broadside and conical diversity patterns is presented for fifth-generation (5G)-NR applications. The capacitive loading is implemented to enhance the port isolation and for size reduction (0.35 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.29 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.047 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ). With an extra slot mode introduced by the coupled feeding scheme, a wide impedance bandwidth is obtained. A miniaturized broadband 180° hybrid coupler is designed to provide in-phase and out-of-phase excitations. It is composed of a quarter-wavelength parallel coupled-line and lumped <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> components. As a result, conical and broadside diversity radiation patterns are achieved. The proposed antenna is analyzed, fabricated, and measured. Good agreement is achieved between the simulated and measured results. The measured overlapped −10 dB impedance bandwidth is 20.5% (3.16–3.81 GHz). The measured in-band isolation is better than 22.7 dB and the peak value achieves 34.7 dB. The proposed pattern diversity antenna exhibits good overall performance, including compact size, wide bandwidth, high isolation, and good radiation performance. Therefore, it is suitable for space-limited 5G-NR applications.

Hybrid TM/TE Cylindrical Leaky Waves: Electromagnetic Radiation at Broadside From Radially Periodic Structures

The nature of broadside radiation from planar, radially periodic structures excited at the center is investigated in this article by considering an annular microstrip antenna operating in the microwave range. This kind of antenna, capable of radiating either a scanned conical pattern or a broadside pencil beam, is typically designed by enforcing that its linearized version supports a single TM leaky mode. However, a single TM cylindrical leaky wave is known to be incapable of radiating a directive broadside beam. To solve the conundrum, a generalized pencil-of-function analysis of the exciting field is performed. It is found that a nonnegligible TE component is present, which exhibits a radial decay different from the TM component but the same complex radial wavenumber. Based on the geometrical symmetries of the structure, an electromagnetic model for the surface currents excited on the annular microstrips is developed and validated by full-wave results for both the currents and the associated radiation patterns. The generality of the adopted approach sheds new light on the nature of the electromagnetic field radiated at broadside by the general class of annular, radially periodic structures, including novel terahertz antennas and plasmonic structures used for achieving extraordinary transmission at optical frequencies.

Conical Kresling origami and its applications to curvature and energy programming

Kresling origami has recently been widely used to design mechanical metamaterials, soft robots and smart devices, benefiting from its bistability and compression-twist coupling deformation. However, previous studies mostly focus on the traditional parallelogram Kresling patterns which can only be folded to cylindrical configurations. In this paper, we generalize the Kresling patterns by introducing free-form quadrilateral unit cells, leading to diverse conical folded configurations. The conical Kresling origami is modelled with a truss system, by which the stable states and energy landscapes are derived analytically. We find that the generalization preserves the bistable nature of parallelogram Kresling patterns, while enabling an enlarged design space of geometric parameters for structural and mechanical applications. To demonstrate this, we develop inverse design frameworks to employ conical Kresling origami to approximate arbitrary target surfaces of revolution and achieve prescribed energy landscapes. Various numerical examples obtained from our framework are presented, which agree well with the paper models and the finite-element simulations. We envision that the proposed conical Kresling pattern and inverse design framework can provide a new perspective for applications in deployable structures, shape-morphing devices, multi-modal robots and multistable metamaterials.

Formation of spiraling infrared emission patterns by controlled interaction of optical filaments.

We analyzed the formation of mid-infrared conical emission patterns possessing spiral and half-ring shaped wavelength contours from a beam of a few optical filaments. The complex patterns were generated and modified experimentally by adaptive wavefront shaping of the femtosecond laser pulse. Mutual interactions between co-propagating filaments can induce curvature in their paths, and the spiral and half-ring emissions were shown to be a direct consequence of this angular deflection. Based on our experimental and computational results, the spirals form in the far-field due to self-interference of conical emission from a helically moving filament. The presented findings will advance the tailoring of spatial conical emission patterns potentially beneficial for spectroscopic applications and terahertz generation.

RESEARCH ON INFLUENCE OF CONSTRUCTIONS SIZES OF THE INTAKE AND CALIBRATION SURFACE OF CHIPLESS TAPS FOR THE PROCESS OF EXTRACTION OF THREAD

The analysis of modern existing methods for producing internal thread showed that one of the most promising methods, with significant technological capabilities and high productivity, is the method of plastic shaping (extrusion) of the thread with chipless taps. The complex of known measures aimed at increasing the stability of taps and their reliability, consisting in the creation of new tool materials, improvement of the design and optimization of the geometry of the cutting part of the taps, improvement of the quality of working surfaces, the use of new types of cooling and optimal settings, do not solve the final issue of high performance and high quality manufacturing of thread holes in stainless and heat-resistant steels not only on highly automated equipment, but even on conventional ones. It is substantiated that the most widespread are taps with a conical full-profile intake part; distortion of the pitch ΔР at he tops of the turns in the transition zone is one of the main design disadvantages of chipless taps. A diagram of the formation of a thread profile by chipless taps with a conical deformation pattern is presented. It is proved that the geometric incompatibility between the thread profile of the tap and the thread formed by it is one of the main reasons for the chipping of the tops located in the transition zone and a sharp increase in the torque of the thread extrusion The parameters of chipless taps are optimized and the advantages of their use in the process of thread extrusion are determined. The main objectives of the research: to investigate the power features of the process of manufacturing threaded holes with chipless taps in stainless steel parts in order to develop optimal designs of taps for through and blind holes; to develop a technological process for the manufacture of chipless taps of the necessary technological equipment for a grinding machine, as well as for grinding the threaded profile of taps.