Coaxial Hole Research Articles

Effects of deep hole drilling processes on the fatigue strength of GTD-111 DS

The paper deals with the effects of electrochemical and electro-discharge deep hole drilling on the high-temperature fatigue behavior of a directionally solidified GTD-111 superalloy. High-temperature HCF tests were carried out at 800 °C on specimens having a coaxial hole drilled with the investigated processes. The hole diameter and length were 1.5 and 95 mm, respectively. The material’s high-temperature HCF S-N curve was also obtained to provide a reference curve. Despite the scatter caused by the material microstructure in the fatigue crack nucleation and propagation regime, the fatigue strength was found to be affected by the investigated hole drilling techniques. The electro-discharge deep hole drilling was found to lower the fatigue strength by 8%. Fractographic analyses showed that it can be attributed to the different hole surface roughness and microstructural alteration in the underlying material.

Design of a transmissive dual-frequency polarization rotator for linearly polarized electromagnetic wave

This paper presents the design of a transmission-type dual-frequency polarization rotator for linearly polarized electromagnetic wave. The rotator facilitates polarization conversion for incident waves at any azimuth angle ϕ at two specific frequency points, resulting in a transmission wave with a counterclockwise rotation of 2ϕ. The proposed polarization rotator structure comprises three metal layers separated by two dielectric substrates. It includes two large rectangular metal patches positioned orthogonally along the x- and y-axes, respectively, as well as two small rectangular metal patches also positioned orthogonally along the x- and y-axes, respectively. The upper and lower metal layers act as the receiving and radiation ends, respectively. The transmitting and receiving ends are interconnected through coaxial metal holes. Remarkably, polarization conversion efficiencies exceeding 0.95 and 0.94 at 12 and 17 GHz, respectively, are achieved, and these high conversion efficiencies remain consistent as the azimuth angle of incidence changes. Furthermore, experimental results obtained from fabricated samples align well with the simulation ones, thus validating the effectiveness of the proposed polarization rotator. The proposed transmissive dual-frequency polarization rotator exhibits good practical application prospects in mobile satellite communications, GNSS, WLAN, etc.

ПОВЫШЕНИЕ ИЗНОСОСТОЙКОСТИ ОТВЕРСТИЙ ЭЛЕКТРОМЕХАНИЧЕСКОЙ ОБРАБОТКОЙ

The results of research in the field of improving the reliability of machinery in the manufacture and restoration of holes of critical parts using surfacing methods, machining by cutting and hardening by electromechanical processing are presented. (Research purpose) The research purpose is improving the quality of repair of body parts by increasing the wear resistance of coaxial holes by electromechanical processing. (Materials and methods) Cylindrical samples made of steel 35 were identified as the object of research after they were surfaced with Np-40G wire and hardened by electromechanical processing. (Results and discussion) It was noted that machine manufacturers do not always provide high quality connections, and first of all by the physical and mechanical properties of the most loaded surfaces of parts. Based on the technical and economic analysis, the choice of surfacing materials was justified in relation to the restoration of coaxial holes of excavator boom. One of the promising methods of operational solution of the problem is the use of electric arc surfacing, mechanical processing by cutting and finishing electromechanical processing. This method allows you to restore the geometric parameters of the holes, increase the hardness and increase the wear resistance of parts. It was established experimentally that after electromechanical processing, the hardness of the deposited metal Np-40G increases from 22-25 to 54-56 on the Rockwell hardness scale. Depending on the modes of electromechanical processing, the depth of the hardened zone can vary from 0.3 to 1.8 millimetres. (Conclusions) On the basis of the conducted research, it was revealed that using the equipment and technology of electromechanical processing, it is possible to make high-quality bushings on a lathe-screw-cutting machine or its use at the final stage of restoration of coaxial holes of the excavator boom by surfacing methods as part of a surfacing and boring complex.

Estimation of the cavity volume in the gasification zone for underground coal gasification under different oxygen flow conditions

In this study, the impact of oxygen flow rate on the cavity of the gasification zone was analyzed through two experiments using a coaxial hole model. The oxygen flow rate was controlled between 3 L/min and 5 L/min for experiment one and between 7.5 L/min and 15 L/min for experiment two. For the estimation of the cavity volume of the gasification zone in UCG, the stoichiometric method, the Delaunay triangulation approach, and the voxelization method were used. The actual gasification zone cavity volume change was obtained by dividing the coal consumption monitored by electronic mass balance by the apparent density of the coal. After analyzing and comparing the cavity volumes of the gasification zone obtained by the three estimation methods with the actual cavity volume of the gasification zone, the results showed that the stoichiometric method had an estimation error of less than 6.5 %. The Delaunay triangulation approach could reduce the estimation error for the convex cavity volume of the gasification zone to within 10 %. The voxelization method could reduce the estimation error for the cavity volume of the gasification zone to below 8 % and accurately describe the shape of the cavity.

14‐2: Angle‐insensitive meta‐surface color filters designed by integrating genetic algorithm with artificial neural network

Next‐generation displays require tiny pixel sizes and are applied to AR/VR and holograms. Conventional color filters have limitations in miniaturization and shows poor reliability from heat, light and other environment. Meta‐surface color filters (MCFs) are one of the solutions to replace conventional color filters, suitable for high‐resolution displays. Structural design parameters are adjusted to determine the filtering properties of the MCFs. In addition, the metal based meta‐surface shows better durability cause of the intrinsic characteristics of the material. However, if the structure is complicated, there require many case‐ studies for verification, which increases trial and error. In addition, resonance by phase matching between structures changes according to the angle of incident light. In this study, we suggest a method to reduce the trial and error required in designing structure. Also, the design parameters of the MCFs of the desired color was extracted through an AI model capable of reverse design. Furthermore, we propose a novel MCFs that shows characteristics independent to the angle of incident light through a coaxial hole and disk array structure.

Operating regimes of a constricted arc discharge in a forevacuum-pressure, plasma-cathode electron source of pulsed large-radius electron beams

We have investigated the operating regimes of a pulsed constricted arc discharge in a forevacuum plasma-cathode electron source of large-radius electron beams. The configuration of the intermediate electrode (IE) with a constricting channel (CC) determines the maximum parameters (current and pulse duration) and operating regimes of the constricted arc. An IE with ceramic (aluminum nitride) CC and an IE with sectional tantalum CC, formed by several electrically insulated tantalum disks with co-axial holes, lead to an increase in the maximum parameters compared to an IE with metal CC. In particular, an IE with sectional tantalum CC provides the highest maximum parameters. The ceramic and sectional tantalum constricting channels also provide lower minimum pressure for which the constricted arc operates stably. When the pressure reaches a certain threshold value, which depends on arc current, a discharge system with IE with sectional tantalum CC provides stable operation for pulse duration up to 10 ms. An increase in pressure provides higher discharge current in the millisecond regime of the discharge operation. When the arc current reaches threshold values from 84 to 92 A (depending on gas pressure), a self-compressed (pinched) mode of operation of the constricted arc occurs. The pinched arc regime is characterized by the highest current and the longest pulse duration. The forevacuum electron source based on the constricted arc discharge with IE with sectional tantalum CC offers generation of low-energy (up to 8 keV) electron beam with current up to tens of amperes and pulse duration up to 10 ms.

Are there bound states in the continuum in a dielectric ring?

Trapping and confining electromagnetic waves is important in both basic research and a variety of applications. For these purposes, various physical mechanisms are exploited including bound states in the continuum, which have been actively investigated recently. Bound states in the continuum have been observed in various objects consisting of both one and a number of dielectric structures. In particular, these photonic states were observed in high-contrast dielectric cylinders in the regime of strong eigenmode coupling, which leads to destructive interference in the far-field zone. In this article, we present the results of a study of bound states in a continuum in a dielectric ring, i.e. cylinder with coaxial air hole. The dependence of the quality factor Q on the normalized diameter of the hole is discussed.

Experimental study on evaluation of underground coal gasification with a horizontal hole using two different coals

Underground coal gasification (UCG) is a technique to extract coal energy with heat energy and combustible gases through chemical reactions in the underground gasifier. In this study, an application of a coaxial UCG system with a horizontal hole is discussed by means of the model UCG experiments with a large-scale simulated coal seam having dimensions of 550 × 600 × 2740 mm. The two types of coal having 30.18 MJ/kg of calorific value with 7.9% of ash (type 1) and 22.66 MJ/kg of calorific value with 28.3% of ash (type 2) were used for the experiments to evaluate the effect of coal quality on temperature distribution of the gasification area and product gas quality. The oxygen-enriched air was used. The injection rate of the gasification agents was elevated during the experiments to analyze the effect on the product gas. The results show that the gasification area is expanded along the wall of a coaxial hole, not upwards for the type 2 coal with high ash content. The average calorific value of product gas for types 1 and 2 is 8.05 MJ/m3 and 6.91 MJ/m3 respectively, while an increase of injection flow rate produces an improvement of the calorific value for both types of coal. Additionally, it is suggested that the reacted carbon and the product gas volume can be estimated with the volume of oxygen injected regardless of the coal quality if the gasification efficiency and the reaction temperature are similar. These results help to estimate several important parameters, e.g. reacted coal amount, recovered gas volume, and recovered energy from the coal when the actual field implementation is designed.

Axisymmetric acoustic oscillations of a rigid spherical shell with two symmetric circular apertures

The plane wave scattering problem for a rigid spherical shell with two coaxial circular holes has been solved rigorously by the Method of Analytical Regularization. An original approach to solving the triple series equations with Legendre polynomials as kernels that arise in the formulation of the problem led to its solution, which is uniformly valid with respect to aperture size. The solution presents two independent infinite systems of linear algebraic equations of the second kind for the even and odd Fourier coefficients respectively. The fast convergence of the systems when truncated is the key to accurate and comprehensive studies of scattering characteristics (total and sonar cross-sections, mechanical force on the walls of doubly-connected sphere) in a wide frequency range. The solution is valid for investigation of the Rayleigh scattering region (where the sphere radius a is much smaller that the wavelength λ), for the resonance region (a∼λ), and also for the deep quasi-optics region (a≫λ), where the radius a of the sphere may be thousands of wavelengths. The unique properties of the obtained solution have been used for calculation of the first 16 complex eigenvalues (in the rigid doubly-connected sphere) with a guaranteed accuracy of 8 significant decimal digits. The new phenomenon of a huge drop in the sonar cross-section σB near the Helmholtz mode (σB/πa2∼10−10) was identified and studied both analytically and numerically. The resonance behaviour of the reflectivity and mechanical force factor is studied in a wide frequency range.

Optical Chirality Enhancement in Hollow Silicon Disk by Dipolar Interference

AbstractOptical chirality enhancement is highly demanded for enantioselective interaction of circularly polarized light with chiral molecules. The chirality enhancement in the coaxial air hole of a hollow silicon disk depends on three aspects, namely, the enhancements of electric and magnetic fields and a factor determined by the phases of their field components. In the spectral regime of dipole resonances, maximum chirality enhancement with sign consistency and uniform spatial distribution in the air hole can be obtained in association with both magnetic dipole resonance and anapole. Due to dipolar interference, the chirality is nulled at their coincidence, around which the sign of chirality is reversed. Maximum chirality with both positive and negative signs can be found between magnetic dipole resonance and anapole in the vicinity of their coincidence. This situation is maintained under size scaling so that the operation wavelength can be broadly tuned. The optical chirality can be further improved by merely adjusting the hole radius, by which the optimal spatially averaged optical chirality enhancement factor can reach 39 and −23. The simple strategy for optimizing Mie resonators presented in this work may benefit the design of Mie resonator‐based achiral metasurfaces for chirality detection application.

Dielectric barrier discharge in radially converging gas flow generating two coaxial and opposite directed non-thermal plasma jets

An original source of non-equilibrium low-temperature plasma jets based on a barrier discharge in a radially converging flow of atomic and molecular gases at atmospheric pressure was developed and created. The discharge electrode system consists of two parallel and coaxial quartz disks, in the geometric center of those two coaxial identical holes were made. On the outer side of each disk a metal foil in the form of a wide ring is glued coaxially to the holes. The gas flow is directed from the periphery of the disks to their center and exits normally to the disks surfaces through narrow holes. As a result, two coaxial and opposite directed plasma jets are formed, which are perpendicular to the disks. There are no analogs of the developed source in literature. The source has been tested for plasma treatment of dielectric yarns that are transported through holes in dielectric barriers and are constantly enveloped in plasma jets. The results show practical possibility of using the developed gas-discharge source for continuous “roll-to-roll” plasma treatment of polymer filaments with the aim to improve their hydrophilicity.

Coaxial hole array fabricated by ultrafast femtosecond-laser processing with spatially multiplexed vortex beams for surface enhanced infrared absorption

Here, we combined shaping and multiplexing of the laser beam to achieve ultrafast femtosecond-laser patterning of Au films with coaxial and circular hole arrays at a printing rate of 106 elements per second. Fabrication quality of the developed parallel laser-printing approach was found to be enough to replicate coaxial hole arrays with a resonant transmission over 90% in the mid-IR spectral range resulted from coupling between localized electromagnetic mode supported by coaxial unit cell and the lattice-type SPPs. Coupling of the surface plasmons localized within the coaxial holes to the vibration modes of the deposited analyte, widely used antihistamine drag Diphendramine, was found to provide around 800-fold enhancement of the amplitude of characteristic IR bands allowing reliable SEIRA-based fingerprint identification at trace concentrations. Our findings are consistent with the calculated amplitude of the electromagnetic hot spots suggesting their predominant contribution to the observed SEIRA effect. The ability to tune in a facile way the hole geometry and arrangement in the process of fabrication allows to tailor the spectral position of the resonance spanning practically relevant spectral range from 4 to 10 μm. This makes the coaxial microhole arrays produced with ultrafast direct laser printing promising for IR filtering and sensing.

Measuring Coaxial Hole Size of Finite-Size Metallic Disk Based on a Dual-Constraint Integration Feature Using Multifrequency Eddy Current Testing

This article presents a new approach of eddy current methods for determining the size of the coaxial hole in the metallic circular disk. In recent decades, for the air-cored sensor probe, the impedance change due to the presence of an infinite metal plate can be calculated by the Dodd–Deeds model. However, in practical measurements, the sample cannot match with the condition required—“infinite”; thus, the Dodd–Deeds model could not be applied to the disk with finite size and certainly not a coaxial hole in the center. In this article, a dual-constraint analytical method is proposed. That is, the upper and lower limits of the integration are substituted with specific values instead of the original 0 and $\infty $ . Besides, it is found that, once the outer radius of the disk is fixed (i.e., the lower limit of integration is fixed), the upper limit reduces linearly as the size of the coaxial hole increases. Both the FEM simulation and experiments have been carried out to validate this method. The radius of the hole can be estimated based on the dual-constraint integration feature.

Measurements of Thickness for Metallic Plates With Co-Axial Holes Using a Novel Analytical Method With the Modified Integration Range

The existence of the hole on a plate affects the calculation of eddy current problems. Consequently, the accuracy for the prediction of the material properties decreases if the effect of the hole is not taken into account. In this paper, a novel analytical method based on the modified integration range is proposed which can address the presence of the hole. Due to the presence of the hole, the conventional Dodd-Deeds analytical solution cannot be used to calculate the inductance change. Therefore, a revised upper integration limit is introduced to replace the original limit - ∞ when using the co-axially air-core electromagnetic sensor. With the presence of the hole, the magnitude of the received signal reduces, and the peak frequency feature changes. The analytical method is validated by measured and numerical simulation results. It is found that the upper limit is related to the radius of the open hole. With the new technique, the thickness of sample plates with holes can be estimated based on the peak frequency feature.

Vector approach in modeling the accuracy of body parts holes manufacturing in aspect of the additive technologies application

The article deals with the issues of ensuring the specified accuracy in the processing of the coaxial and intersecting body parts holes. Features of a details design this type body parts are considered. Parametric analysis was performed, and the key parameters affecting the accuracy of machining body parts internal holes were identified. It is offered at development of details production technology to use in the course of technological parameters system calculation of the vector equations which solution is the only combination of technological parameters of processing of body parts holes. The geometric parameters that determine the position of the basing holes in space are determined. In the vector form shows the influence of the location errors of the base holes and the intersecting and coaxial body parts holes during processing. A spatial calculation scheme for determining the error of the arrangement of the group of coaxial holes of the body part is presented. The work compares results of simulation of the processing errors of the body type parts holes of the for standard cycles for machining holes with the simulation results of the error processing errors of the body type parts holes of manufacturing processes based with additive technologies. It is established a significant impact on the accuracy of the holes location the rotation of details in the working area of the machine, as well as its reinstallation. The efficiency of application of hybrid technological cycles based on additive technologies in the production of coaxial holes in the body type parts is shown.

Numerical study on the flow over two circular disks in tandem arrangement

The flows over the two circular disks in tandem arrangement at low Reynolds numbers are numerically studied using large-eddy simulations. Both disks have the same aspect ratio (χ = d/w = 5, where d and w are, respectively, the diameter and the thickness of the disk), while the upstream disk has a coaxial hole in D diameter. First, the effect of the Reynolds number on the near-wake evolution of the tandem disks with spacing of l/d = 0.1 is investigated. Compared with a single circular disk, it is found that the upstream apertured disk (D/d = 0.2) delays the wake transition. Four bifurcations, i.e., “Steady state,” “Zig-zig,” “Zig-Zag,” and “Weakly chaotic” modes, are captured at critical Reynolds numbers of 178, 207, 212, and 275, respectively. Second, the effect of disk spacing on near-wake evolution is studied for Re = 200 and D/d = 0.2. The wake is steady and planar-symmetric at l/d = 1, in which a totally new wake mode characterized by a three-thread wake is observed. The wake becomes unsteady but planar-symmetric at l/d = 1.5. At l/d = 2, however, the planar-symmetric wake structures are all broken. The upstream disk wake retains planar-symmetry, while the downstream disk wake is similar to the “Reflectional-symmetry-broken” mode in a single disk wake. The planar symmetry is recovered for both disks at l/d = 6. It is found that for l/d > 3, the interaction between the two disks becomes weaker as the spacing increases. Finally, the effect of disk spacing on the drag and lift coefficients for each disk is examined. When disk spacing is constant, the lift coefficient of the upstream disk is always lower than that of the downstream disk. The drag coefficient of each disk in tandem is smaller than that of a single disk. With the increase in disk spacing, the drag coefficient of the upstream disk changes little while the drag coefficient of the downstream disk increases rapidly.

Transmission Enhancement in Coaxial Hole Array Based Plasmonic Color Filter for Image Sensor Applications

Plasmonic color filters based on the hexagonal arrangement of coaxial hole array in aluminum have been demonstrated as a promising candidate for color filter development due to polarization and incident angle insensitivity. They also comprise a single nanometer thick metal film, demonstrate good line width, CMOS compatibility, and fine color tunability. However, the low transmittance of the coaxial hole array based filters limits their use in potential applications such as image sensors and displays. This paper introduces a new method to increase transmittance in coaxial hole array based filters by tuning localized surface plasmons and surface plasmon polaritons. In this method, coaxial holes of small diameters are filled along with a large size coaxial hole array to form a combined filter geometry with optimized parameters in aluminum film using computational techniques. The simulation results will have potential applications in CMOS image sensors, submicron pixel development, microdisplays, and liquid crystal over silicon devices.

Autonomous neuro-registration for robot-based neurosurgery.

Neuro-registration is of primary importance as it has a bearing on the accuracy of neurosurgery. Although the accuracy of surgical robots is within the acceptable medical standards, the overall surgical accuracy is dictated by the errors in the neuro-registration process. The purpose of this work is to automate the neuro-registration process to improve the overall accuracy of the robot-based neurosurgery. A highly accurate 6-degree-of-freedom Parallel Kinematic Mechanism (6D-PKM) robot is used for both neuro-registration and neurosurgery. In neuro-registration, after measurement of points in the medical image space, the end-platform of the 6D-PKM surgical robot carrying the camera will autonomously navigate towards the fiducial markers to measure its coordinates in the real patient space. An accurate relationship between the medical image space and the real patient space is established, and the same robot will navigate the surgical tool to the target. In order to validate the proposed method for autonomous neuro-registration, experiments are performed using four phantoms. The four phantoms are as follows: PVC skull model, two acrylic blocks and a glass jar with coaxial shells. These phantoms are specifically designed to simulate the neurosurgical process. All the phantoms are registered successfully using the above-stated method. After autonomous neuro-registration, the coordinates of the target point are determined. Neurosurgery validation is carried out by attaching a 1-mm-diameter needle to the robot platform, which is autonomously traversed to reach the target point passing through the two 2-mm-diameter coaxial holes. The experiments are repeated, and the results reveal very good repeatability. A method for autonomous neuro-registration has been developed. The robot has been successfully registered using the above method. After successful neuro-registration the overall accuracy of the robot-based neurosurgery is considerably improved. The other benefits of the above method are as follows: elimination of line-of-sight problem, no need of extra unit for neuro-registration, less time for registration, intraoperative registration, human error reduction and low cost.

РАЗРАБОТКА И ОБОСНОВАНИЕ ПАРАМЕТОВ СВЧ УСТАНОВКИ СО СФЕРИЧЕСКИМ РЕЗОНАТОРОМ ДЛЯ ТЕРМООБРАБОТКИ БОЕНСКИХ ОТХОДОВ

The improvement of microwave technology and the design of installations, that ensure the matching of the processes of dehydration, grinding and heat treatment of non-food animal slaughter waste is an urgent task. The purpose of the work is the development and justification of the effective parameters of the operation of a microwave plant for heat treatment of non-food waste of animal origin of high humidity in a continuous mode, which ensures the improvement of the quality of the feed product with the least operating costs. In the work we used statistical processing of the results of the research, using computer programs Microsoft Excel 10.0, Statistic 5.0, 3D modeling of the design of microwave installations in the Compass-3D V15 program. The developed microwave device with a spherical perforated resonator provides for combining the processes of dewatering, grinding and heat treatment of raw materials in a continuous mode. It contains a rotating spherical resonator in a spherical shielding body, with a receiving and unloading nozzles. A dielectric shaft is rotated along the vertical axis of the resonator, rotating from the electric motor. The upper parts of the spherical shielding unit and the spherical resonator, whose diameter is matched to the wavelength, are as close as possible to each other, and have coaxial holes for fixing the receiving branch pipe and the dielectric shaft. On the outside of the shielding case, a chopper and microwave generators are installed, so that the emitters are directed into the rotating spherical resonator uniformly along the perimeter of the dielectric plate segment. The spherical resonator is perforated, the dimensions of the holes are coordinated with the particle sizes of the finished products. An operating-technological scheme for the operation of a device with a spherical diffraction cavity for heat treatment of raw materials in a continuous mode is developed. The microbiological indices of the non-food waste of animals slaughter after exposure of electromagnetic fields and ultrahigh frequencies were estimated. As a result of the research, a microwave technology was developed for heat treatment of non-food waste of slaughter animals with high humidity for the production line of protein feed, using a spherical perforated resonator. A positive evaluation of the microbiological indices of a product, treated in an electromagnetic field of an ultrahigh frequency, was carried out.

Plasmonic Colour Filters Based on Coaxial Holes in Aluminium.

Aluminum is an alternative plasmonic material in the visible regions of the spectrum due to its attractive properties such as low cost, high natural abundance, ease of processing, and complementary metal-oxide-semiconductor (CMOS) and liquid crystal display (LCD) compatibility. Here, we present plasmonic colour filters based on coaxial holes in aluminium that operate in the visible range. Using both computational and experimental methods, fine-tuning of resonance peaks through precise geometric control of the coaxial holes is demonstrated. These results will lay the basis for the development of filters in high-resolution liquid crystal displays, RGB-spatial light modulators, liquid crystal over silicon devices and novel displays.