Copper Ring Research Articles

High sensitivity metamaterial thin film: bio and thermal sensors based on Fano resonances and nematic liquid crystals

ABSTRACT In this research, a new sensor was designed that exhibits high biological and thermal sensitivities. It is suitable for use as a biosensor, a thermal sensor, or both simultaneously. This nanostructure sensor is based on two non-identical copper rings, which are dependent on two dielectric environments, and has been optimised to enhance sensitivity. To control and increase the sensitivity of the designed metamaterial, the E7 liquid crystal was used, which has a temperature-dependent refractive index. The optimised data indicate that the highest sensitivity for the structural parameters; R, dr and d are 70, 43 and 30 nm, respectively. This nanostructure demonstrates a refractive index sensitivity of 500 nm/RIU and a very high temperature sensitivity of 11 nm/K in the wavelength range of 500–1000 nanometres and a temperature range of 290–330 Kelvin. The second peak has the highest sensitivity to the refractive index and the third peak has the highest sensitivity to temperature. The high temperature sensitivity reported is at a 90-degree orientation angle of the liquid crystal director. Therefore, the simulation and optimisation of this ultra-thin film indicates that it can be suitable for use as a high-quality bio-thermal sensor with a high figure of merit.

Analysis of a passive vibration damper for high-speed superconducting magnetic bearings

Superconducting magnetic bearings (SMB) based on a combination of high temperature superconductors and permanent magnets enable the realization of self-stabilized high-speed devices with significantly reduced friction. However, external vibration might couple in the bearing resulting in large amplitude oscillations due to a resonance case. A dedicated eddy current damper (ECD) might be used to eliminate these oscillations for a stable operation. The influence of such damping elements was studied for a frictionless SMB twisting system designed to speed up the conventional ring spinning process. Therefore, conductive copper rings with different thicknesses were implemented at different positions into the bearing setup as ECD. Afterward, the SMB setup was analyzed during acceleration using an array of laser distance sensors to record the displacement of the levitating permanent magnet ring in radial and axial direction, respectively. Simultaneously, a numerical model was developed to investigate the influence of the ECDs on the dynamic and static behavior of the SMB in more detail. It was shown that the simulated damping coefficients are in good agreement with the measured values, which allows further optimization of the ECD with the developed numerical model.

Assessment and factors affecting quality of life among patients with Wilson’s disease

Wilson’s disease is caused by abnormal copper metabolism resulting in deposition in various organs, including the brain, liver, and cornea, thus disrupting organ function. It is characterized by encephalopathy, extrapyramidal symptoms, progressive liver failure, and copper ring deposition in the cornea. Management of this disease should include quality of life maintenance; however, relevant studies on this topic are lacking. This study aimed to assess the factors affecting the quality of life (QoL) of patients with Wilson’s disease. A cross-sectional survey using convenience sampling was conducted between July 2020 and March 2021 at the hospital. Data on patient characteristics, 36-item Short-Form General Health Survey, Uniform Wilson Disease Rating Scale, and Hamilton Depression Rating Scale scores were collected. Associations among quality of life depression, anxiety, and Wilson’s disease progression were examined using Pearson correlation analysis. Factors affecting the quality of life of patients, including depression, anxiety, liver function, clinical symptoms, diet, liver function, brain magnetic resonance imaging (MRI) findings, disease duration, Barthel Index, and Morse scores were examined using multivariate linear regression analysis. This study included 134 patients with Wilson’s disease whose mean age was 29.12 ± 8.59 years. The mean QoL score in the patient group was 71.38 ± 9.55 points and was negatively correlated with anxiety (r = − 0.883, P = 0.000), depression (r = − 0.852 P = 0.000), and clinical symptoms (r = − 0.542, P = 0.000) scores. Anxiety, depression, and clinical symptoms severity are vital factors for the QoL of patients with Wilson’s disease. The study provides foundational evidence to design novel interventions, including symptom management, diet, and self-care ability, which can help in improving the quality of life in patients with Wilson’s disease and decreasing the burden associated with this disease.

Dumbbell shaped structure loaded modified circular ring resonator based perfect metamaterial absorber for S, X and Ku band microwave sensing applications

In this paper, a new metamaterial absorber (MMA) is presented that exhibits peak absorptions at 3.26 GHz, 11.6 GHz, and 17.13 GHz within S, X, and Ku bands. The unit cell of the proposed MMA is constructed on an FR4 substrate having an electrical dimension of 0.144λ × 0.144λ, where wavelength, λ is calculated at the lowest absorption frequency. The unique structural design of the unit cell consists of two concentric copper rings with which dumbbell-shaped structures are attached. The rotating symmetrical structural design of this MMA provides around 93.8%, 96.47%, and 99.95% peak absorptance in the mentioned frequencies, which is invariable with the change of incident angle as well as polarization angle. The metamaterial properties of the proposed absorber are studied along with the surface current analysis. The MMA shows single negative behaviour and it also exhibits high-quality factors (Q factor) of 21.73, 41.42, and 51.90 at maximum absorptance frequencies. The MMA is analysed by it's equivalent circuit to understand the resonance phenomenon, which is verified through simulation in Advanced Design Systems (ADS) software. The testing is done on the developed prototype of the proposed MMA. Measurement results are in close proximity to the simulation results. Due to its high Q factor, high EMR, and insensitivity to polarization and angle of incidence, it can be utilized as a part of miniaturized microwave device. In addition, the proposed MMA can exhibit high sensing performance and flexibility to differentiate different oils in S, X, and Ku bands.

A Model with Feedback Mechanism for Learning Hand-Eye Coordination: A Pilot Study.

Practicing neuroendoscopic skills like hand-eye coordination is mandatory before embarking on actual surgeries. Synthetic models are able alternatives for cadavers and animals. Presently available models in the literature are either very costly or lack a feedback mechanism, which makes training difficult. We aimed to make a basic low-cost neuroendoscopic hand-eye coordination model with a feedback mechanism. An electronic circuit in series was designed inside a clay utensil to test inadvertent contact of the working instrument with implanted steel pins, which on completion lighted a light-emitting diode (LED) and raised an alarm. Two exercises-moving-a-rubber exercise and passing copper rings of multiple sizes were made and tested by 15 neurosurgeons. The moving-a-rubber exercise was completed by 6/15 (40%) neurosurgeons in the first attempt, 6/15 (40%) in the second, and 3/15 (20%) in the third attempt. For the 1.5 cm copper ring passing exercise, 12/15 (80%) successfully performed in the first attempt; for 1 cm copper ring, 6/15 (40%) performed in the first; and for the 0.5 cm copper ring, 1/15 (6.6%) performed in the first attempt. The time to finish all the exercises significantly decreased in the third successful attempt compared to the first. The model gave excellent feedback to the trainee and examiner for basic neuroendoscopic hand-eye coordination skills.

Polarization insensitive passive loaded wideband metamaterial absorber

Abstract This paper proposes a lightweight frequency selective surface polarization-insensitive wideband metamaterial absorber in C band and X band that employs only a few resistive elements. The proposed absorber is embodied with four quadrature slotted inner circular patch, which is horizontally and vertically bisected, and outer concentric copper rings of 0.035 mm thickness are attached with four lumped resistors placed at 90° apart. A slotted inner circular patch provides significant inductive and capacitive loading. The absorption bandwidth of 8.02 GHz with more than 90% absorption is observed from 5.69 to 13.71 GHz under normal incidence and maintains almost same absorptivity range under oblique incidence up to 45° in both transverse electric mode and transverse magnetic mode. The designed metamaterial absorber is fabricated and measured using free space measurement technique. The actual experiments and the simulated ones are in good agreement.

Iskustva u zavarivanju gasovoda "Turski tok" i interconector Srbija - Bugarska

The gas pipeline "Turski Tok" was built in the period from 2019 to 2021 with a total length of 403 km (Zaječar-Horgoš). The pipeline has a capacity of up to 15 billion cubic meters, a diameter of 1219 mm and its thickness is 14.27 mm. The steel L485MEPSL2 was used for production. The SerbiaBulgaria interconnector is 109 km long (Niš-Sofia), with a capacity of 1.8 billion cubic meters of gas, a diameter of 711 mm and the thickness is 8.7 mm. Steel X52 was used for its construction. Different procedures were used for welding: • Welding E-111 (cellulose and basic coating). • MAG 135 with welding of the root of the welded joint with a semi-automatic device STT, and filling with an automatic procedure with two devices. • Welding with the MAG process of the root of the welded joint on the inside, using the internal centralizer, and on the outside with the automatic MAG process with two devices. • Welding from the outside with automatic MAG process with two devices, Self-Shielded Flux Cored Arc Welding wire FCAW-114 using an internal centralizer with a copper ring. The paper presents experiences with gas pipeline welding, with a critical review of selected solutions and suggestions for optimizing welding technology.

Development of a direct PMMA-PCB bonding method for low cost and rapid prototyping of microfluidic-based gas analysers.

Rapid prototyping of microfluidic devices requires low cost materials and simple fabrication methods. PMMA and PCB have been used separately for the fabrication of microfluidic devices in a wide range of applications. Although the combined use of PMMA and PCB can have considerable merits, few works have been reported on the direct bonding of these materials. In this work we have investigated the fabrication of microfluidic devices using PMMA and PCB for the analysis of gaseous samples. In order to yield a reliable direct bonding method, four parameters including temperature, pressure, solvent and patterned interface material were experimentally investigated. Results of testing various prototypes showed that a patterned interface of concentric rectangular copper rings exposed to solvent at room temperature and under moderate pressure provided better adhesion strength, sealing and durability. After successful development of the PMMA-PCB direct bonding process, sample prototypes were designed and fabricated to practically assess the combined advantages of two materials. Presented concepts include implementation of heater on a PCB, array of gas sensors coupled with microchannels, serpentine microchannel and fast evaporation of liquid sample using an SMD resistor. It has been shown that advantages of utilizing PMMA such as fabricating the channel easily and with low cost, can be combined with benefits of a PCB including simple sensor installation and the use of copper tracks and electronic components for gas flow modulation. Moreover, it is possible to implement channel, circuit and other electronic components such as microprocessors on a single device.

Optimization of the Powers Exchanged between a Cascaded Doubly Fed Induction Generator and the Grid with a Matrix Converter

The use of an electromagnetic converter of great reliability in wind energy, like the cascaded doubly fed induction generator (CDFIG), can solve several problems compared to the doubly fed induction generator (DFIG), among them the elimination of the brushes and copper rings. The work consists of studying the performance of a CDFIG-based wind system using a matrix converter and a variable pitch control system. The traditional PI is able to successfully solve a number of linear control problems. The fuzzy logic controller used can dramatically improve the system's performance. The active and reactive energy transferred between the CDFIG and the grid can be controlled by adjusting the machine inverter. The DC bus voltage has been kept stable by controlling the grid inverter. The pitch controller's objective is to maximise aerodynamic power while staying within the converter's power limits. Numerical simulation results implemented in the MATLAB/Simulink package will be provided in this study to show that the suggested control strategy is both possible and effective.

Triple band frequency tunable polarization insensitive metamaterial absorber for WLAN and 5G applications

A triple band metamaterial absorber (MMA) has been demonstrated in this paper that is developed on an FR4 substrate targeting WLAN and 5G frequencies. The resonating patch contains three modified concentric copper rings having overall unit cell dimensions of 0.16λ0 × 0.16λ0 × 0.0128λ0, where the wavelength, λ0 is for 2.4 GHz. The MMA exhibits 99.3%, 95.68%, and 99.5% peak absorption at 2.4, 3.5, and 5.85 GHz, respectively. Length variation of inwardly extended metallic stubs attached to the innermost ring provides frequency tuning flexibility for peak absorption within 5.67 GHz–5.98 GHz. The absorption process of the MMA is analyzed through the distribution of surface current. The MMA exhibits incident and polarization angle insensitive behaviour up to 60° for both TE and TM modes with near zero polarization conversion ratio. The resonance characteristics are justified through equivalent circuit modelling with validation by Advanced Design software (ADS). The measured absorption indicates a close resemblance with the simulation. Moreover, a good effective medium ratio of 6.25 shows the compactness of MMA. Due to its compact structure, incident, and polarization angle insensitivity, and near unity absorption at application-specific frequencies, this perfect MMA can be suitable for WLAN and 5G applications, especially for microwave shielding and sensing.

Dual ionization sources high-field asymmetric waveform ion mobility spectrometry with combined ultraviolet lamp source and corona discharge source

Dual ionization sources combining an ultraviolet (UV) lamp source and a corona discharge (CD) source were first used as ionization sources for high-field asymmetric waveform ion mobility spectrometry (FAIMS) to switch ionization modes without changing hardware. The CD source was manufactured using a tungsten needle and a copper ring and its usability was verified. The UV source and the CD source were combined into the FAIMS sensor and multiple ionization modes were attempted by controlling their on-off status. The optimal flow rate, quantitative and qualitative capabilities of the system were investigated, and the experiments on the impact of humidity and interferent on the system were conducted. The experimental results indicated that the flow rate of 3–4 L/min could ensure sufficient sensitivity and resolution of the system. The dual ionization sources configuration provided richer qualitative and quantitative information for FAIMS. This platform could operate in three ionization modes and had the potential to expand the analyzable compounds of UV-FAIMS. In summary, the research demonstrates that the dual ionization sources could be used as ionization sources for FAIMS, and the combined system provided convenience for chemical analysis.

Preconception contraceptive use and miscarriage: prospective cohort study

ObjectivesTo evaluate the association between preconception contraceptive use and miscarriage.DesignProspective cohort study.SettingResidents of the United States of America or Canada, recruited from 2013 until the end of 2022.Participants13 460 female...

FFT-Based Approach for the Mechanical Analysis of Superconducting Rutherford-Type Cables

Low-temperature superconductors are widely used in high field accelerator magnets, mostly within Rutherford type cables. We have proposed the “CoCaSCOPE” approach in order to build a numerical model of impregnated low-temperature Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting Rutherford-type cables dedicated to mechanical computation. Here the strand structure is described as a bi-metallic material: a copper core, a superconducting bundle region and an outer copper ring. In this paper, we explore the use of the distributed solver AMITEX_FFTP based on Fast Fourier Transform (FFT). The main interest of this method is to reduce the simulation time. This approach is investigated for structures with linear material behavior in this paper. This work compares the results from the FFT approach (using AMITEX) and from the 3D Finite Elements approach (using Cast3M). In this way, we can demonstrate the higher performances of FFT-based solving method compared to the finite elements method for multi-scale structure such as Rutherford-type cables in terms of computation time. With this approach, we can reduce the computation time or, alternatively, increase the size of our models in order to analyze the behavior of a macroscale model under mechanical solicitation.

Concepts of heat dissipation of a disposal canister and its computational analysis

The stability of engineered barriers in high-level radioactive waste disposal systems can be influenced by the decay heat generated by the waste. This study focuses on the thermal analysis of various canister designs to effectively lower the maximum temperature of the engineered barrier. A numerical model was developed and employed to investigate the heat dissipation potential of copper rings placed across the buffer. Various canister designs incorporating copper rings were presented, and numerical analysis was performed to identify the design with the most significant temperature reduction effect. The results confirmed that the temperature of the buffer material was effectively lowered with an increase in the number of copper rings penetrating the buffer. Parametric studies were also conducted to analyze the impact of technical gaps, copper thickness, and collar height on the temperature reduction. The numerical model revealed that the presence of gaps between the components of the engineered barrier significantly increased the buffer temperature. Furthermore, the reduction in buffer temperature varied depending on the location of the gap and collar. The methods proposed in this study for reducing the buffer temperature hold promise for contributing to cost reduction in radioactive waste disposal.

Simulation model of a non‐contact triboelectric nanogenerator based on electrostatic induction

AbstractBased on the coupling effects of contact electrification and electrostatic induction, a triboelectric nanogenerator (TENG) can convert mechanical energy into electric power, which is at the cutting edge of alternative energy technology. Although a considerable number of TENGs with different configurations have been designed, some of them however, which only depend on the electrostatic induction effect have not received enough attention. Here, a non‐contact TENG model consists of copper rings and charged dielectric sphere is presented, which is aimed at exploring the working process of TENGs caused by electrostatic induction. Two classical models, including vertical and horizontal double copper rings models are also proposed. Relevant advanced and accurate models of TENGs have been established through the finite element method. We anticipate that the constructed model and theoretical analysis are helpful for the design of non‐contact model TENGs with complicated geometric construction, and expand their applications in various fields.image

Research on the Vibration Behavior of Ring–Block Friction Pair Made of Materials of Water-Lubricated Rubber Bearing under Special Operating Conditions

A water-lubricated rubber bearing (WLRB) is prone to generate frictional vibration noise under special operating conditions, which seriously affects the acoustic stealth performance of warships and threatens their navigation safety. Meanwhile, the main factor affecting the frictional vibration behavior of a WLRB is the materials of the friction pair. Therefore, this work selects a friction pair composed of a copper ring and a rubber block as the research object and studies the frictional vibration behavior of the ring–block friction pair under low-speed and starting conditions. The real friction coefficient curve is used to establish a transient dynamic finite element analysis model for the ring–block friction pair. The effects of the load, friction coefficient, and Young’s modulus on the frictional vibration behavior under special operating conditions are studied. The analysis’s results show that the frequency of the medium-high frequency friction-induced vibration disappears under low-speed operating conditions when the friction coefficient is below 0.1. During the startup process, even if the friction coefficient is very low, the medium-high frequency friction-induced vibration still exists. The research results provide ideas for future theoretical research and guidance suggestions for engineering practice.

An investigation on the vacuum brazed diamond film and copper using low-temperature Ag-Cu-Sn-Ti filler alloys: Interfacial microstructure and mechanical performance

The diamond microwave window is usually employed in the fusion reactor such as the international thermonuclear experimental reactor (ITER). To promote its fabrication, the diamond film needs to be brazed with copper rings. In this work, the diamond-copper combination was vacuum brazed using low-temperature AgCu-10Sn-1Ti filler alloys. The effects of brazing temperature and soaking time on the microstructure and mechanical performance of the joints were investigated. The Raman technique was used to probe the distribution of notorious residual stresses in the joints. Lastly, the intrinsic relationship between the microstructure, shear strength, and residual stresses of the joints was built. When brazed at low temperature or for short soaking duration (720 °C/5 min), some solidification defects and intermetallic clusters were formed, due to insufficient elemental diffusion and poor flowability of the interlayer. Increasing the brazing temperature or extending the soaking time would eliminate these defects, leading to microstructural homogeneity. The joint average shear strength optimized reached 256 MPa at 750 °C for 10 min. In such a case, the tensile stresses near the diamond/interlayer interface guided the fracture process. Otherwise, the metallurgical quality of interlayer would be responsible for the joint bond strength. The work performed furnished the way for the preparation of diamond microwave windows from technical and theoretical aspects.

Optimized AgCuSnTi filler alloy for brazing of diamond/copper combination used in microwave windows: Microstructure and mechanical performance

For the fabrication of diamond microwave windows, a solid joining of diamond with copper rings is critically required. In this work, the AgCu-mSn-nTi filler alloys were designed to braze the diamond and copper. The typical joint microstructure was characterized and its formation mechanism was unveiled. The effect of Ti or Sn fraction on the microstructure and joint shear strength was examined. Finally, an inherent relationship between the microstructure and joint bond strength was clarified. The joint average shear strength optimized reached 256.1 MPa when brazed using AgCu–10Sn–1Ti. With more Ti addition, excessive CuSn3Ti5 compounds produced early failure in the interlayer. Increasing Sn content helped to densify the interlayer. However, rigid Cu5Sn formed declined the joint strength when Sn was over 15 wt%. The work performed provided an optimized filler composition for low-temperature joining of diamond and copper and would guide the fabrication of diamond windows theoretically and technologically.

The analysis and experimental research of ultrahigh vacuum ConFlat-type flange joints applied in accelerator and space technology

Finite element analysis (FEA) of ultrahigh vacuum ConFlat-type flange joints for both Wheeler's and CERN's models were carried out. These models differ in the angle of inclination between the two shelves of knife-edge. The main value of this research is a computer simulation for deformable flanges and gaskets because all analyses before this have been done for absolutely rigid flanges (non-deformable flanges) and deformable gaskets. The analysis variable parameters are the radius of rounding at the tip of the knife-edge (0.05 … 0.2 mm), the angle between the shelves forming the knife-edge (70° and 90°) and the material properties of the copper ring (annealed and 1/4 hard). The calculation of bolted connections for tightening the flanges was also carried out as the experience has shown that during the tightening of bolts, they reach the yield point and begin to deform plastically. That leads to incomplete tightening of the flanges and, therefore incomplete sealing of the joint. The experimental research of the flanges tightening and the comparison with computer simulation results were carried out.

Transmission Performance of Halbach Array Cylindrical Permanent Magnet Governor

A novel cylinder permanent magnet governor (CPMG) with Halbach segmentation is proposed in this paper. In order to improve the transmission performance of the CPMG, different permanent magnet (PM) arrangement methods are adopted. To achieve a fair comparison result, all the PMs are of the same size. The main magnetic fluxes are considered to obtain a comprehensive equivalent magnetic circuit model of the CPMG with Halbach array and analytical output torque that is calculated. The analytical method of transmitted torque for CPMG is then presented. Additionally, the effect of the average output torque of CPMG under parameters of the thickness of the copper rings, the slip rate and the effective coupling of the copper rings are investigated. Finally, the prototype platform is ready for testing on the field. The results were consistent with the results of the simulation, and the error was kept within the range of 5%. This research can provide a theoretical and practical reference for the optimal design of the transmission characteristic of CPMG.