Metal Ring Research Articles

Broadband control of flow of light using plasmonic metasurfaces consisting of arrays of metallic split ring nanoantennas

When a metallic U-shaped nanoantenna (split ring resonator) is observed from its sides, variations in the viewing angle can lead to significantly different size and shape projections. In this study, we demonstrate that plasmonic metasurfaces consisting of arrays of such nanoantennas can support unique side (in-plane) scattering switching and routing processes. These processes encompass a polarization switching centered at 1.6 μm, which is driven by the coherent excitation of the nanoantennas’ multipolar modes. They also include spectrally broadband (0.5–1.6 μm) directional control of the flow of in-plane light scattering. Such a process includes a total prohibition of light emerging from one side of the metasurface for a given polarization of the incident light. However, when such polarization is rotated by 90°, the flow of the in-plane scattering opens with high efficiency. We further discuss the impact of the formation of surface lattice resonance on the coherent amplification of infrared scattering around 1.6 μm and its switching process. The results underscore the influence of variations in asymmetry, associated with the sizes and shape projections, on interference processes. They also showcase how in-plane scattering has the capacity to transfer distinct characteristics of plasmonic near-field asymmetries induced by optical fields into far-field scattering.

Measuring device for systems of technical vibro-diagnosis of power equipment

RELEVANCE. Among the various methods for assessing the technical condition of power equipment, vibration diagnostics occupies an important place. Therefore, improving the quality of hardware for vibration diagnostics is currently extremely important. THE PURPOSE. To develop a vibration sensor with a new principle of operation for systems of technical vibration diagnostics of power equipment, as well as to theoretically substantiate the performance of the proposed sensor. METHODS. When solving the set goal, the main provisions of the theory of vibration diagnostics were applied. RESULTS. A design of the vibration acceleration sensor has been developed, the peculiarity of which is that it is excited by means of constructive coupling capacitors, the first electrode of which is made in the form of a thin-walled metal split cylinder, the role of the second electrodes is performed by the lower row of the winding of each measuring coil, and the function of the inertial element is performed by a screen made in the form of a metal ring fixed on a suspension in the form of a membrane. Based on the electrical equivalent circuit of the sensor, a theoretical substantiation of its operability and efficiency was made. Variants of circuit solutions for the primary and secondary measuring transducers of the measuring device for vibration diagnostics systems have been developed. The primary measuring transducer contains directly a vibration displacement sensor, a sinusoidal voltage source, an input differential measuring amplifier and an analog filter containing a narrow-band filter, a broadband amplifier and a buffer amplifier. The secondary measuring transducer contains a quadrature detector of information signals, an output buffer amplifier and a quadrature reference voltage driver. A block diagram of the hardware solution for the vibration acceleration registration system is also proposed. CONCLUSION. The developed sensor has improved output characteristics and can be used not only for vibration control of power equipment, but also for measuring mechanical vibrations in technical diagnostic systems of various other machines and mechanisms, as well as for tasks of spectral seismic exploration.

Together or Separate: What is best practice when imaging bilateral hands for rheumatoid arthritis examinations?

A current gap identified in medical imaging (MI) literature is a standardised approach to bilateral hand examinations. This examination performed concurrently or unilaterally results in different effects on radiation dose and image quality, both of which are important to the diagnostic and follow-up imaging of rheumatoid arthritis (RA) patients. An experimental study was undertaken using anthropomorphic hand phantoms at the Queensland University of Technology (QUT) MI Simulation laboratory. Images of the hand were acquired individually and then concurrently with both hands together. Radiation dose was calculated by observing dose area product (DAP) reading on a digital radiography system, with the additional use of an exposure metre as a secondary data collection method. Image quality was quantified through measuring distortion caused by beam divergence, by exploring the separation of two metal rings fixed to the hand phantom. The overall radiation dose was higher for the unilateral technique by 10.15% at the digital radiography system console and 11.96% recorded by the exposure metre. In the second part of the experiment, the unilateral technique produced 0 mm of distortion when the phantom was positioned in the central part of the beam. The concurrent technique demonstrated an average of 3.65 mm of distortion, when both hands were positioned with the central part of the beam between them. The unilateral technique should be performed for bilateral hand examinations. The increase in distortion from the concurrent technique is clinically significant, as the diagnostic grading of RA is measured in millimetre increments. The additional overall examination dose is minimal when compared to the improvement in image quality.

Theoretical modeling and experimental verification of an improved radial composite transducer consisting of a metal ring and a radially polarized piezoelectric stack

In the ring radial transducer, the wall thickness of the radially polarized piezoelectric ceramic is limited by the polarization technology and operating voltage, resulting in the limited power capacity and vibration ability of the transducer. Hence, an improved novel radial composite transducer (nRCT) is proposed in this paper, which consists of a radially polarized piezoelectric stack and a metal ring. Piezoelectric stack is used to enhance vibration and effectively solve the problem of difficult excitation caused by large wall thickness. A new electromechanical equivalent circuit model (EECM) of the nRCT in radial vibration is established, and the relationship between frequency characteristics of the nRCT and geometric size is analyzed. The finite element method (FEM) is used to carry out numerical modeling of the nRCT and the traditional radial composite transducer (tRCT), and preliminarily verify the calculation results of EECM. Compared with the tRCT, under the same electrical excitation, the equivalent electrical impedance of the nRCT designed in this paper decreases to 26%, and the radial vibration displacement increases to 142%. Finally, the nRCT and the tRCT are fabricated, and the experimental results have well verified the results of the theoretical analysis. The proposed radial piezoelectric stack model provides a new idea for the optimal design of radial vibration piezoelectric devices, which is expected to be further applied to the design of hydrophones, piezoelectric transformers, and medical ultrasound devices.

Radio wave propagation analysis with dominant path model using MIMO antenna element for vehicular base station application

AbstractA low-profile slant ±45° polarized antenna for a 4G/5G base station with a dominant path wave propagation model (DPM) is reported in this paper. For dual-polarization and wide impedance bandwidth, the two dipole radiators are crisscrossed and a square metallic ring is integrated with the dipole arms and screwed with the four shorting vias. The antenna operates in Band 40/41/42/43 with strong isolation and low ECC (Envelop Correlation Coefficient). Fabricated antenna results show that the predicted wideband antenna has 13.38% bandwidth in 4G, which is Band 40/41, and 29.33% bandwidth in 5G sub-6 GHz Band 42/43. The antenna has a consistent radiation pattern, a 40 dB XPD (Cross Pol Discrimination), and a beam width of 69.5° ±1.5° in the entire frequency band. Three base station sites were explored to deploy the radiation pattern of a dual-polarized antenna in the 3D EM (Electromagnetic Analysis) tool. To evaluate signal quality, strength, radio network planning, and wave propagation analysis by analyzing antenna performance in real-time scenarios with 64 and 256 QAM (Quadrature Amplitude Modulation) techniques. For the proposed four-stream MIMO (Multiple-Input-Multiple-Output) antenna arrangement at deployed cell sites for 4G/5G base station applications, the maximum downlink and uplink data rates are 3.826/2.8 Mbps and 1044/800 Mbps respectively.

Design of Dual-Band Antenna for Metal-Bezel Smartwatches With Circular Polarization in GPS Band and Low Wrist Effect

A dual-band antenna with circular-polarization (CP) in GPS band and low wrist effect for metal-bezel smartwatches is proposed and studied in this paper. The proposed antenna consists of a metal ring, a capacitor, a system ground plane with a feeding network, and a metal plane. The dual-band operation with CP in GPS band is analyzed based on the theory of characteristic mode (TCM), where the CP is achieved by the capacitor. The low wrist effect, which is analyzed based on the electric-field distributions, is realized by a metal plane. On the wrist, with the help of the metal plane, the antenna efficiencies are improved from -9.8 dB to -6 dB and -7.3 dB to -4.6 dB in the GPS and WiFi/BT bands, respectively. In addition, the AR in GPS band is improved from 4.5 dB to 2.4 dB. A prototype shows that, on the wrist, the measured return loss is better than 8.6 dB and 6.7 dB in the GPS and WiFi/BT bands, respectively. The measured efficiencies are -6.6 dB and -5 dB respectively in the two bands. The measured 3-dB AR bandwidth is 30 MHz (1558 MHz-1588 MHz). Also, the proposed antenna has stable performance on the wrist. The dual-band antenna with high efficiencies in the GPS and WiFi/BT bands, good AR in GPS band, and stable performance on the human wrist, is promising for practical application.

Broadband achromatic electromagnetic beam control based on reflective metamaterial

The emergence of metasurfaces has shown great potential in planar optics. From visible light to infrared wavelengths, various forms of metasurfaces have been studied to control electromagnetic waves. Due to the dispersive properties of light waves, the application of metasurfaces in broadband devices is limited. We design a metasurface for broadband efficient achromatic transmission in the terahertz band. After optimized design, an achromatic deflector and an achromatic focusing device were obtained. By changing the geometric parameters of the metal ring to meet the phase and dispersion requirements of the metasurface, broadband achromatic metasurfaces and focusing metasurfaces are realized in the range of 1.8–2.3 THz.

(286) Goldmember: A Novel Approach to Remove Entrapped Metal Rings Around a Penis

Abstract Introduction Penile strangulation with metal objects is a rare urologic emergency that can present considerable challenges. The treatment approach can vary depending on the type of constricting device, degree of injury, and available equipment. Prior medical reports document the use of various instruments such as bolt cutters, oscillating saws, and power drills. Our case demonstrates a safe and reproducible means to remove metal rings entrapped around a penis using the Midas Rex® drill. Objective To describe a novel treatment approach in penile strangulation with the use of the Midas Rex® drill. Methods A 70-year-old male with a history of paranoid schizophrenia presented to our institution’s emergency department with urinary retention and penile pain due to the placement of five rings onto the penis two weeks prior. On exam, he had swelling of the glans and skin necrosis underneath the rings (Figure 1). After initial bedside attempts to remove the rings proved unsuccessful, he was promptly taken to the operating room. Further attempts to remove the rings using orthopedic pin cutters were also unsuccessful. Next, the Midas Rex® drill (Figure 2a) was used to cut each ring into two segments. The penis was protected from traumatic and thermal injury with careful retraction and continuous irrigation (Figure 2b). All five rings were successfully removed without sustaining iatrogenic injuries (Figure 2c). The injuries were limited to pre-existing superficial wounds of the penile skin (Figure 3a). A cystoscopy was performed and did not reveal any evidence of urethral injury. A suprapubic catheter (SPC) was placed to allow for urethral rest with 1,200 ml of urine drained. Postoperatively, the patient was stable and was transferred to the inpatient psychiatric unit the next day. After adjustment of his psychiatric medications and six days of observation, he was discharged. At his two-week urology follow-up, he had near-complete healing of the penile skin (Figure 3b). His SPC was also removed with low post-void residual noted. Results We present a case where mechanical methods could not be used to remove entrapped metal rings around a penis. In cases requiring the use of electrical tools, it is of utmost importance to protect the penis from iatrogenic injuries. Although the use of non-medical devices such as electric saws have been described in penile strangulation, they can often be bulky. Also, in several reports these devices have caused thermal injuries, leading to urethral strictures and urethrocutaneous fistulae. We were able to use the Midas Rex® drill, an instrument typically used in neurosurgical and orthopedic procedures, with excellent results. By using the diamond-tipped metal cutter attachment and powering the drill with compressed nitrogen set at 120 psi, all five metal rings were safely removed in under 30 minutes. Conclusions Penile strangulation represents a rare urologic entity requiring prompt removal of constricting devices to avoid ischemic complications. From our experience, we demonstrated that the Midas Rex® drill can be safely and expeditiously used to remove metal rings entrapped around a penis with minimal risk of iatrogenic injury. Disclosure No

Gas gun driven dynamic expansion of 3D-printed AlSi10Mg rings

This paper presents a new experimental setup to study dynamic fragmentation of metallic rings manufactured by 3D-printing technology. The ring is inserted over a ductile thin-walled tube which is impacted axially by a conical-nosed cylindrical projectile fired by a single-stage light–gas gun. The diameter of the projectile is larger than the internal diameter of the thin-walled tube, which expands as the projectile advances, pushing radially outwards the metallic ring, that eventually breaks into multiple fragments. The impact velocities considered in the present experimental campaign range from 197 m/s to 385 m/s. The AlSi10Mg ring specimens are printed by Selective Laser Melting technique, with an inner diameter of 14 mm and square cross section of 2 × 2 mm2. To obtain time-resolved information on the mechanics of fragmentation, the number of fractures, and the size of the fragments, the tests have been recorded with two-high speed cameras. A tunnel-shaped soft casing made of polymer foam is placed around the specimen to softly recover the ejected fragments, that have been weighted and sized to determine the statistics of the fragments size distribution. In addition, the predictions of the fragmentation theory of Kipp and Grady (1985) for the evolution of the number of fragments with the impact velocity have been compared with the experimental evidence, and an excellent quantitative agreement has been found within the whole range of loading rates investigated. Compared to other available techniques for dynamic fragmentation of rings, in which the expansion of the specimen is driven by electromagnetic or explosive loading, this experimental setup stands out for its simplicity, fast operation, quick assembly, and flexibility to test different engineering materials, which facilitates performing extensive experimental campaigns (34 successful tests have been carried out in this research). To the authors’ knowledge, this paper presents the most comprehensive data set to date on the fragmentation of dynamically expanded printed rings, including the first high-resolution video recordings of the formation of multiple cracks throughout the circumference of the samples, and scanning electron microscopy images of the fractures showing the porous microstructure on the cracks surface.

Plasmonic Photochemistry as a Tool to Prepare Metallic Nanopores with Controlled Diameter for Optimized Detection of Single Entities

AbstractPlasmonic solid‐state nanopores with tunable hole diameters can be prepared via a photocatalytic effect resulting from the enhanced electromagnetic (EM) field inside a metallic ring on top of a dielectric nanotube. Under white light illumination, the plasmon‐enhanced EM‐field induces a site‐selective metal nucleation and growth within the ring. This approach is used to prepare Au and bimetallic Au–Ag nano‐rings and demonstrate the reduction of the initial inner diameter of the nanopore down to 4 nm. The tunability of the nanopore diameter can be used to enable optimized detection of single entities with different sizes. As a proof‐of‐concept, single object detection of double stranded DNA (dsDNA) and Au nanoparticles (AuNPs) with a diameter down to 15 nm is performed. Numerical simulations provide insights into the EM‐field distribution and confinement, showing that a field intensity enhancement of up to 104 can be achieved inside the nanopores. This localized EM‐field can be used to perform enhanced optical measurements and generate local heating, thereby modifying the properties of the nanopore. Such a flexible approach also represents a valuable tool to investigate plasmon‐driven photochemical reactions, and it can represent an important step toward the realization of new plasmonic devices.

A Rare Case of Fatal Penile Strangulation in a Transgender Woman.

Penile strangulation is a surgical emergency with significant morbidity and potential mortality. It is often associated with psychiatric disorders; objects such as metal rings, plastic bottles, and rubber bands are commonly used. The San Francisco Office of the Chief Medical Examiner was presented with a 50-year-old transgender female decedent with a medical history of psychiatric and substance use disorders. Autopsy revealed external genitalia entrapped by a plastic bottle encircling the penile shaft at the base, causing severe edema and skin blebs of the penile shaft and glans, and evidence of urinary obstruction. We describe the accidental death of an adult transgender female decedent due to penile strangulation, which ultimately led to acute renal failure and death.

Enhanced Deep-Red Phosphorescence in Cyclometalated Iridium Complexes with Quinoline-Based Ancillary Ligands.

Compounds with good photoluminescence quantum yields (ΦPL) in the deep-red to near-infrared parts of the spectrum are desired for a variety of applications in optoelectronics, imaging, and sensing. However, in this region of the spectrum, quantum yields are usually modest, which is explained by the energy gap law and the inherently slower radiative decay rates for low-energy emitters according to the second-order perturbation theory. In this work, we outline a new direction in deep-red luminescence, introducing a new suite of bis-cyclometalated iridium complexes with efficient luminescence beyond 650 nm. Seven new complexes are prepared using two different cyclometalating (C^N) ligands with four quinoline-derived ancillary ligands (L^X). The chosen cyclometalating ligands are well-established to produce deep-red phosphorescence and include a metalated phenyl ring appended to a conjugated heterocycle. The ancillary ligands combine a rigid quinoline or benzoquinoline "L" donor with a variable anionic "X" donor comprised of an O-donor aryloxy or carboxylate or an N-donor amidate. These complexes phosphoresce in the deep-red region with wavelengths between 650 and 700 nm and solution quantum yields between 0.018 and 0.42.

Spoof surface plasmon polariton supported by square ring metasurface for wearable body area network

A metasurface consisting of a 2D periodic square lattice of metallic square ring resonators is considered for supporting spoof surface plasmon polariton (SSPP) modes. First, SSPP modes are highlighted by simulated dispersion curves. The dispersion curves are analyzed by considering hybridization of modes in either a patch or an aperture array with frequency shifts. Hybridization of modes is also supported by means of surface current and electric field mappings showing consistent symmetric and anti-symmetric fields. Second, it is shown that a dipole antenna located near the metasurface is able to generate SSPP modes. The transmission spectra between two antennas located at each extremity of the metasurface show transmission enhancements compared with propagation in free space. The transmission enhancements are shown for different locations of the antennas either facing each other or positioned in diagonal. Finally, the transmission enhancement is connected to SSPP modes by comparing the transmission spectra and the measured dispersion curves with each other. Specifically, two transmission windows measured for an embroidered metasurface are related to the cutoff frequency of the two SSPP modes supported by the metasurface as evidenced by the measured dispersion curves.

Evaluation the behavior of Ring Footing on Gypseous Soil Subjected to Eccentric and Inclined Loads

An extensive program of laboratory testing was conducted on ring footing rested on gypseous soil brought from the north of Iraq (Salah El-Deen governorate) with a gypsum content of 59%. There are limited researches available, and even fewer have been done experimentally to understand how to ring footings behave; almost all the previous works only concern the behavior of ring footing under vertical loads, Moreover, relatively few studies have examined the impact of eccentric load and inclined load on such footing. In this study, a series of tests, including dry and wet tests, were carried out using a steel container (600×600×600) mm, metal ring footing (100 mm outer diameter and 40 mm inner diameter) was placed in the middle of the container top surface that filled with the gypseous soil. Subject to (vertical and inclined) (concentric and eccentric) loads was carried out for dry and soaking soil to discover the differences in bearing capacity as well as ring behaviors. According to the results when the load eccentricity increases on the ring footing from the rate (e = 0B, e = 0.04B e = 0.08B, e = 0.16B) and the inclination load increases as (0°, 5°, 10°, 15°) respectively the ring footing ultimate loads will be reduced.

Thermally controllable electromagnetically induced transparency in a coupled terahertz metamaterial

We investigate the thermally controllable electromagnetically induced transparency (EIT) effect in a planar terahertz (THz) metamaterial configuration comprising metallic semi-circular split ring resonators (MSCSRR) integrated with indium antimonide (InSb). In transmission configuration, a transparency window is observed by placing a horizontal cut wire (HCW) in close proximity to the MSCSRR. It develops by frequency detuning and strong near-field coupling between both the bright resonators. The transparency window is found to be controllable with temperature along with the structural parameters of the unit cell. The blue shift of 0.028 THz is observed when the temperature increases from 260 K to 320 K. Moreover, the group delay of the designed EIT structure can also dynamically tune by varying temperature of InSb. The shift from 3.19 ps to 1.98 ps is observed when the temperature increases from 260 K to 320 K. We used a coupled harmonic oscillator model to thoroughly understand the coupling between resonators and interpret the transparency effect. Our findings can be closely predicted from the model. The present study can be significant for the development of active and controllable terahertz photonic components such as slow light systems, buffers, etc.

Numerical Analysis of the New Wireless Relay Transmission Model Based on FEM

In this article, a wireless relay transmission system in long-distance wells with new close winding helical coils is proposed. This system can realize more efficient bottom-up superposition transmission of signals in long transmission wells. At the same time, by redesigning the structure of the transmitting and relay antennas, a close winding helical coil structure with metal ring protection is proposed to excite quasi-TEM waves, which improves the efficiency of signal transmission in each channel and the compressive strength of the antenna. The simulation and experimental results demonstrate that under long distance and harsh stratum conditions, the wireless transmission system in long-distance wells has excellent signal transmission performance at extremely low frequencies. Compared with previous antenna structures, the new helical coil has better performance in transmission efficiency. This new wireless relay transmission system can greatly meet the long-distance transmission and conditions of oil and gas wells in the future.

Strangulation of the Penis by Metal Ring on a Right Inguino-Scrotal Hernia: About a Case at Sikasso Hospital

Strangulation of the penis by a metal ring is a rare situation in urology. It requires emergency care because it can jeopardize the functional prognosis of the penis. We report the case of strangulation of the penis by a metal steel ring associated with a right inguino-scrotal hernia from which we will present the non-surgical management of this urological emergency.

Dry reforming in a dielectric barrier discharge reactor with non-uniform discharge gap: Effects of metal rings on the discharge behavior and performance

The application of dielectric barrier discharge (DBD) plasma reactors is promising in various environmental and energy processes, but is limited by their low energy yield. In this study, we put a number of stainless steel rings over the inner electrode rod of the DBD reactor to change the local discharge gap and electric field, and we studied the dry reforming performance. At 50 W supplied power, the metal rings mostly have a negative impact on the performance, which we attribute to the non-uniform spatial distribution of the discharges caused by the rings. However, at 30 W supplied power, the energy yield is higher than at 50 W and the placement of the rings improves the performance of the reactor. More rings and with a larger cross-sectional diameter can further improve the performance. The reactor with 20 rings with a 3.2 mm cross-sectional diameter exhibits the best performance in this study. Compared to the reactor without rings, it increases the CO2 conversion from 7% to 16 %, the CH4 conversion from 12% to 23%, and the energy yield from 0.05 mmol/kJ supplied power to 0.1 mmol/kJ (0.19 mmol/kJ if calculated from the plasma power), respectively. The presence of the rings increases the local electric field, the displaced charge and the discharge fraction, and also makes the discharge more stable and with more uniform intensity. It also slightly improves the selectivity to syngas. The performance improvement observed by placing stainless steel rings in this study may also be applicable to other plasma-based processes.

Multi-functional metamaterial polarization convertor in S/C/X bands

In this study, a reflective multi-functional metamaterial polarization converter printing two connected metal rings and two unconnected metal square patches on a metal backed FR4 substrate is designed in S/C/X Bands. The lowest operating frequency of the proposed polarizer is starting from 2.41 GHz. Linear to linear (LTL) polarization conversion at three bands: 2.41–2.52 GHz, 3.77–4.16 GHz, and 7.02–7.37 GHz as well as linear to circular (LTC) polarization conversion at 7 bands: 2.35–2.38 GHz, 2.58–2.65 GHz, 3.49–3.63 GHz, 4.32–4.36 GHz, 6.73–6.86 GHz, 7.5–7.62 GHz, 9.77–9.87 GHz are achieved in this design. Both numerical simulations and experimental validation are provided for this polarization converter. Performance of the proposed and some referenced polarization converters are also compared to represent the advantages of the proposed design.

EFFICIENCY ENHANCEMENT OF PHOTOVOLTAIC SOLAR CELLS USING METAMATERIALS ABSORBING SCREEN

This paper proposes a novel technique for the efficiency enhancement of photovoltaic (PV) solar cells using metamaterials absorbing screens. This kind of engineered material comprises resonant metallic rings that are printed on a host low-loss dielectric substance and made periodic in a two-dimensional lattice. The absorbing screen has been carefully designed, and its retrieved effective constitutive parameters, effective electric permittivity ϵeff and effective magnetic permeability µeff, are integrated within a numerically modelled amorphous-Silicon-based PV solar cell structure as an impedance matching layer. Such arrangement will greatly achieve matching between the effective impedance of the composite solar cell structure and free-space impedance and will result in higher photons absorption through the metamaterials anti-reflective screen. Numerical full-wave electromagnetic simulations are carried out using CST Microwave Studio for the design of a metamaterial absorbing screen. Due to the large computational resources required, COMSOL Multiphysics was adopted in the design and analysis of the composite structure comprising a two-dimensional PV solar cells layer. Based on the numerical results, both optical and electric characteristics of the PV solar cell structure were enhanced with the use of a metamaterial layer. Moreover, efficiency enhancement by 5% was permissible, in which efficiency reached 12% with the use of metamaterials as compared to the efficiency of the classical PV cells of 7%. The obtained results are very promising, and the potential integration of metamaterials in commercial PV solar cells will show significant advancement in efficiency enhancement of PV cells and realization of smart PV solar cells with the consideration of additional features from metamaterials.