Truncated Hollow Cones Research Articles

High-performance THz Metallic Axial Mode Helix Antenna with Optimised Truncated Hollow Cone Ground Plane for 6G Wireless Communication System

The Terahertz (THz) band antenna configuration operates in the 0.1–10 THz frequency range and offers a stable performance for future 6th Generation (6G) wireless communication systems. However, the available metallic axial mode helix antenna designs exhibit a peak directivity of lower than 18 dBi within 0.5–1 THz, making it inappropriate to be applied in wireless communication systems. Therefore, this study proposed a high-performance THz metallic five-turn axial mode helix antenna with an optimised truncated hollow cone ground plane for 6G wireless communication systems. Following the creation of the proposed antenna design using cost-effective copper (annealed), the truncated hollow cone ground plane of the THz axial mode helix antenna was optimised via simulation in a Computer Simulation Technology Microwave Studio (CST MWS) software and a verification of the proposed THz antenna design in Analysis System High-Frequency Structure Simulator (Ansys HFSS) software for a fair comparison. Based on the results, the proposed THz metallic axial mode helix antenna with optimised truncated hollow cone ground plane recorded an impedance bandwidth of 0.46 THz, Fractional Bandwidth (FBW) of 61.33% for |S11| ≤ -10 dB, and a maximum directivity and realised gain of 21.8 dBi and 21.5 dBi at 0.85 THz, respectively. Within the 0.5–1 THz, the proposed optimised THz antenna design achieved an outstanding performance, including an FBW of more than 50%, excellent directivity of higher than 15.8 dBi, radiation efficiency of greater than 87%, circular polarisation, and low-profile helix turns. In short, the proposed THz metallic axial mode helix antenna with optimised truncated hollow cone ground plane design is appropriate for various THz 6G wireless applications.

Performance evaluation of a solar thermal storage system proposed for concentrated solar power plants

This study aims to assess the performance of the Hybrid Solar Thermal Storage (HSTS) system, the storage system proposed for concentrated solar power (CSP) plants. The heat storage hybridisation concept is based on coupling latent phase change material (PCM) and thermochemical storage system containing paired metal hydride (MH) beds. One base design which uses only thermochemical heat storage mode and two designs of the HSTS system with two distinct PCM heat exchanger designs (i.e., shell-and-tube and cylinder with truncated hollow cones) are proposed and numerically investigated. To predict the dynamic behavior of the three storage systems, a bidimensional mathematical model is established and a numerical code written in Fortran-90 is developed. Key performance indicators used to evaluate the performance of the three storage systems include volumetric storage capacity, specific power, state of hydrogen charge, and energy storage efficiency. Comparing the performance of the three systems reveals that the HSTS system's energy storage efficiency increased by 36% due to the integration of a reaction heat recovery internal system based on Na3Al as PCM. The use of the PCM in truncated hollow cones resulted in a 36.4% reduction of the heat charging and discharging time, an 18.5% increase storage capacity, and a 54.1% increase in specific power. In addition, this study proves that the third design can be imlpemented as a HSTS system in a solar power plant with the following performance indexes: 128 W/kg- Mg2FeH6, 160 MJ/m3 and 88% for specific power, volumetric storage capacity and energy storage efficiency, respectively.

4D Printing of shape-memory polymeric scaffolds for adaptive biomedical implantation

4D printing has shown great potential in a variety of biomedical applications due to the adaptability and minimal invasiveness of fabricated devices. However, commonly employed shape memory polymers (SMPs) possess undesirable transition temperatures (Ttranss), leading to complications in implantation operations. Herein, we demonstrate 4D printing of a new SMP named poly(glycerol dodecanoate) acrylate (PGDA) with a Ttrans in a range of 20 °C - 37 °C making it appropriate for shape programming at room temperature and then shape deployment within the human body. In addition, the material possesses suitable rheological properties to allow for the fabrication of a variety of delicate 3D structures such as “triangular star”, “six-petal flower”, “honeycomb”, “tube”, tilted “truncated hollow cones”, as well as overhanging “bridge”, “cage”, and “mesh”. The printed 3D structures show shape memory properties including a large fixity ratio of 100% at 20 °C, a large recovery ratio of 98% at 37 °C, a stable cyclability of > 100 times, and a fast recovery speed of 0.4 s at 37 °C. Moreover, the Young's moduli of the printed structures can be decreased by 5 times due to the phase transition of PGDA, which is compatible with biological tissues. Finally, in vitro stenting and in vivo vascular grafting demonstrated the geometrical and mechanical adaptivity of the printed constructs for biomedical implantation. This newly developed PGDA SMP based 4D printing technology has the potential to pave a new route to the fabrication of shape memory scaffolds for personalized biomedical applications.

Combination of Reactive-Ion Etching and Chemical Etching as a Method for Optimizing the Surface Relief on AlGaInN Heterostructures

A relief on the surface of GaN previously released from the growth substrate is formed by a combined method in which reactive ion etching is used in combination with liquid etching (in KOH or hydrochloric-acid solutions). The dependence of obtained relief on the sequence of operations used is studied. It is shown that etching in a KOH solution followed by reactive ion etching provides the appearance of truncated hollow cones on the surface. In experiments, the ability of a hydrochloric-acid solution for etching exclusively GaN relief elements formed by reactive ion etching of the surface is also found. As a result, reactive ion etching of the sample followed by immersion into hydrochloric acid forms objects of cylindrical shape on its surface transforming at the base into conical or strongly distorted pyramidal structures. The appearance of this relief can be explained by the predominance of the chemical component in reactive ion etching with increasing distance from the sample surface. Further optimization of the relief parameters obtained as a result of combined etching is possible by varying the modes of operation under use.

A Paul trap with sectored ring electrodes for experiments with two-dimensional ion crystals.

We have developed a trapped ion system for producing two-dimensional (2D) ion crystals for applications in scalable quantum computing, quantum simulations, and 2D crystal phase transition and defect studies. The trap is a modification of a Paul trap with its ring electrode flattened and split into eight identical sectors and its two endcap electrodes shaped as truncated hollow cones for laser and imaging optics access. All ten trap electrodes can be independently DC-biased to create various aspect ratio trap geometries. We trap and Doppler cool 2D crystals of up to 30 Ba+ ions and demonstrate the tunability of the trapping potential both in the plane of the crystal and in the transverse direction.

Portable Skin Analyzers with Simultaneous Measurements of Transepidermal Water Loss, Skin Conductance and Skin Hardness.

Simultaneous measurement of skin physiological and physical properties are important for the diagnosis of skin diseases and monitoring of human performance, since it provides more comprehensive understanding on the skin conditions. Current skin analysis devices, however, require each of probes and unique protocols for the measurement of individual skin properties, resulting in inconvenience and increase of measurement uncertainty. This paper presents a pen-type skin analyzing device capable tomeasure three key skin properties at the same time: transepidermal water loss (TEWL), skin conductance, and skin hardness. It uses a single truncated hollow cone (THC) probe integrated with a humidity sensor, paired electrodes, and a load cell for the multimodal assessment of the skin properties. The present device measured TEWL with a sensitivity of 0.0068 (%/s)/(g/m2/h) and a linearity of 99.63%, conductance with a sensitivity of 1.02 µS/µS and a linearity of 99.36%, and hardness with a sensitivity of 0.98 Shore 00/Shore 00 and a linearity of 99.85%, within the appropriate ranges for the human skin. The present pen-type device has a high potential for the skin health diagnosis as well as the human performance monitoring applications.

Truncated Hollow Cone Probe for Assessing Transepidermal Water Loss and Skin Hardness.

This study proposes a skin analysis device using a truncate hollow cone (THC) probe for measuring both transepidermal water loss (TEWL) and skin hardness. Because skin health is closely related to the epidermal barrier function and skin mechanical property, it isimportant to measuretheirbiophysical indicatorsat the same time, to understand skin conditions anddiagnose skin disorders such as atopic dermatitis and systemic sclerosis. Previous skin analyzers, however,required different probes with different protocols for eachbiophysical indicators, whichmakes the measurement inconvenient and increases the measurement uncertainty. The present device consists of a THC probe equipped with humidity and force sensors, and an actuator that simultaneously measure both TEWL and skin hardness which indicate the integrity of the epidermal barrier function and the skin mechanical property, respectively. Using artificial reference skins, the prototype device showedthe TEWL with a sensitivity and linearity of0.011 (%/s)/(g/m2/h) and 99.5%, and the hardness with 0.075 N/(Shore 00) and 97.6%, respectively, which are within the appropriate range for the properties of human skin. The on-body measurement of five subjects showed that the proposed device could measure both the TEWL and skin hardness without any crosstalk from each other. The proposed device has great potential for in-depth analysis of the health status of the skin which could indicate various skin diseases.

Axisymmetric problems of the theory of elasticity for a truncated hollow cone

An exact solution of the axisymmetric problem of the theory of elasticity for a hollow circular cone, truncated by two spherical surfaces (the ends of the cone), taking into account the natural weight or temperature (the inhomogeneous Lame equations) is given. The conditions of sliding clamping are satisfied on the conical surfaces, the stresses on one of the ends of the cone are specified, while the boundary conditions can be arbitrary on the other end.

Frequencies and mode shapes for thick truncated hollow cones

The finite element method of analysis is employed to study the vibration of truncated thick hollow cones. The three-dimensional strain–displacement equations are used to formulate the finite element in the conical coordinate system. Axial symmetry is assumed and the formulation is reduced to two dimensions while maintaining the three-dimensional character of the analysis. The accuracy of the analysis is established by comparing results for free–free boundary conditions with existing solutions. The effects of different boundary conditions, including fixed–free and fixed–fixed, are studied to determine their effects on the frequency of vibration. Frequency results are given for an additional boundary condition corresponding to a layer attached to the exterior of a rigid cone. Nondimensional results for an isotropic material with Poisson's ratio of 0.3 are presented in terms of tables, plots of frequency versus cone apex angle and plots of selected mode shapes.

Vibration of Truncated Conical Cylinders of Crystal Class 6/mmm

A nine-node Lagrangian finite element is formulated in an axisymmetric conical coordinate sys tem and used to study the vibration of truncated hollow cones. The governing elasticity equations (strain- displacement) are derived using the generalized expressions for orthogonal curvilinear coordinates. The transformation for hexagonal material constants from a Cartesian coordinate system to the conical coordi nate system is illustrated and results are presented for titanium and beryllium. Results for frequency and mode shape are presented in tabular form and graphically for hexagonal materials of class 6/mmm for a vari ety of truncated cone parameters. Vibration frequencies for isotropic cones are compared with similar results in the existing literature.

NUMERICAL CALCULATION OF VIEW FACTORS FOR AN AXIALLY SYMMETRICAL GEOMETRY

Abstract A new numerical method for calculating the view factors for an axially symmetrical geometry has been developed. The assumption is that each object can be approximated by a truncated hollow cone. The method consists of two parts. One is to determine the accepting region and the other the integration over that region. It is accurate and fast since the determination and the integration are analytical. It was compared with the area integration and Monte Carlo methods for concentric coaxial cylinders, and was seen to be 19 times and 3 times faster than them, respectively. It was applied to a CZ puller.

Three-Dimensional Vibrations of Truncated Hollow Cones

This work presents a three-dimensional (3-D) method of analysis for determining the free vibration frequencies and corresponding mode shapes of truncated hollow cones of arbitrary thickness and having arbitrary boundary conditions. It also supplies the first known numerical results from 3-D analysis for such problems. The analysis is based upon the Ritz method. The vibration modes are separated into their Fourier components in terms of the circumferential coordinate. For each Fourier component, displacements are expressed as algebraic polynomials in the thickness and slant length coordinates. These polynomials satisfy the geometric boundary conditions exactly. Because the displacement functions are mathematically complete, upper bound values of the vibration frequencies are obtained that are as close to the exact values as desired. This convergence is demonstrated for a representative truncated hollow cone configuration where six-digit exactitude in the frequencies is achieved. The method is then used to obtain accurate and extensive frequencies for two sets of completely free, truncated hollow cones, one set consisting of thick conical shells and the other being tori having square-generating cross sections. Frequencies are presented for combinations of two values of apex angles and two values of inner hole radius ratios for each set of problems.