Circular Loop Research Articles

Dual-resonance microwave probe for magnetic field mapping

This paper introduces a dual-resonance probe for mapping magnetic fields in electromagnetic compatibility (EMC) applications. The probe, consisting of a circular loop loaded with a 6-turn circular spiral, exhibits two resonant modes via capacitive coupling, resonating at 1.158 GHz and 1.582 GHz to cover L1 and parts of the L5 band. Designed for GPS applications, the presented equivalent circuit model of the probe simplifies its design. The probe maps the orthogonal magnetic field component at its resonant frequencies. Measurements, taken while scanning over a short-circuited microstrip line and a rat-race hybrid coupler, closely match their simulated orthogonal magnetic field component. The proposed probe offers advancements in sensitivity enhancing EMC in various electronic systems.

A system dynamics model based on ISM for risk perception in emergency by employees in chemical industrial parks

Risk perception is one of the factors that guide human behavior in the workplace. In accident prevention and emergency response, the risk perception of employees affects the safety behaviour and efficiency of emergency disposal. Besides, risk perception is a complicated process restricted by many influencing factors. The study aims to identify the most important factors affecting risk perception. This study had three phases. In the first, factors affecting the risk perception were extracted based on the questionnaire survey and the expert scoring. Then, the Interpretive Structure Model (ISM) was used to stratify the 14 influencing factors of risk perception and obtain a hierarchical structure chart. Finally, by analyzing the influence paths in the ISM, the system dynamics feedback loop diagram was constructed. The model took the state variable “risk perception→ risk response→ risk identification→ risk communication→ risk perception” as the main circular loop, and was supplemented and perfected by multiple feeder loop circuits. Research indicates risk experience is the most fundamental factor affecting risk perception. In the aspect of sensitivity analysis, the study shows that the risk perception of employees is related to the distance of the risk source. Its effectiveness in quantifying qualitative data, identifying influential factors, and establishing cause-effect relationships make it a valuable tool for enhancing risk perception in chemical industry park.

Effect of salinity-clay variation on the transient magnetic field in the Quaternary aquifer, theoretically and practically

This study focuses on understanding the physical foundations of the transient electromagnetic method, such as the transition from a simple basic principle to a more complex principle, starting from the Biot-Savart law until the current concept. It calculates the steady and transient magnetic fields around any electrical wire system. Accordingly, this law will be used to determine the magnetic field around the square loop configuration, which matches the magnetic field arising from the circular loop configuration. The square loop equation was derived and extended to include changes in the half-space, which allows us to understand how the electromagnetic waves travel in the subsurface and the farthest point, that can record the TEM response from the TEM loop, according to the loop size and loop current. Accordingly, the deduced equations were applied to predict the transient magnetic field curves of the Quaternary aquifer in three different water zones along the Nile delta, depending on the values of resistivity and chargeability caused by the variations in salinity and clay contents. The calculated transient magnetic curves were then compared with other measured field curves to confirm the validity of the derived equations. Therefore, these curves are expected to be used as guide curves for the transient magnetic field response in this aquifer. Also, these curves are important in estimating the hydro-geophysical characteristics of the main groundwater aquifer in the selected area and in other areas with the same geologic and hydrogeologic settings. Also, a common model is presented for any delta environment in the world in measured and calculated data.

Application repetition and electrode-tissue contact result in deeper lesions using a pulsed-field ablation circular variable loop catheter.

Pulsed-field ablation (PFA) is a novel, myocardial-selective, non-thermal ablation modality used to target cardiac arrhythmias. Although prompt electrogram (EGM) signal disappearance is observed immediately after PFA application in the pulmonary veins, whether this finding results in adequate transmural lesions is unknown. The aim of this study is to check whether application repetition and catheter-tissue contact impact lesion formation during PFA. A circular loop PFA catheter was used to deliver repeated energy applications with various levels of contact force. A benchtop vegetal potato model and a beating heart ventricular myocardial model were utilized to evaluate the impact of application repetition, contact force, and catheter repositioning on contiguity and lesion depth. Lesion development occurred over 18 h in the vegetal model and over 6 h in the porcine model. Lesion formation was found to be dependent on application repetition and contact. In porcine ventricles, single and multiple stacked applications led to a lesion depth of 3.5 ± 0.7 and 4.4 ± 1.3 mm, respectively (P = 0.002). Furthermore, the greater the catheter-tissue contact, the more contiguous and deeper the lesions in the vegetal model (1.0 ± 0.9 mm with no contact vs. 5.4 ± 1.4 mm with 30 g of force; P = 0.0001). Pulsed-field ablation delivered via a circular catheter showed that both repetition and catheter contact led independently to deeper lesion formation. These findings indicate that endpoints for effective PFA are related more to PFA biophysics than to mere EGM attenuation.

Chemical Recycling of Poly(cyclohexene carbonate)s via Synergistic Catalysis.

Chemical recycling of polymers to the corresponding monomers offers a valuable solution to address the current plastics crisis for creating an ideal and circular polymer economy. Here, we present a bimetallic synergistic depolymerization of the widely studied CO2-based polycarbonates, poly(cyclohexene carbonate)s, to epoxide monomers efficiently. The bimetallic CrIII-complex-mediated highly selective depolymerization and repolymerization was achieved via the regulation of reaction temperature, thus closing the circular loop of poly(cyclohexene carbonate)s in situ. Mechanistic investigation has revealed that the formation of epoxides undergoes a direct chain-end unzipping process. A bimetallic catalysis involving a nucleophilic attack of the metal-alkoxide species toward the methine carbon atom bound with an adjacent carbonyl that is activated by the other metal center features a lower energy barrier in DFT calculations, which promotes the epoxide extrusion.

Blockchain-enabled architecture for lead acid battery circularity

Widespread use of lead acid batteries (LABs) is resulting in the generation of million tons of battery waste, globally. LAB waste contains critical and hazardous materials, which have detrimental effects on the environment and human health. In recent times, recycling of the LABs has become efficient but the collection of batteries in developing countries is not efficient, which led to the non-professional treatment and recycling of these batteries in the informal sector. This paper proposes a blockchain-enabled architecture for LAB circularity, which ensures authentic, traceable and transparent system for collection and treatment of batteries. The stakeholders—battery manufacturers, distributors, retailers, users, and validators (governments, domain experts, third party experts, etc.)—are integrated in the circular loop through a blockchain network. A mobile application user interface is provided to all the stakeholders for the ease of adoption. The batteries manufactured and supplied in a geographical region as well as the recycled materials at the battery end-of-life are traced authentically. This architecture is expected to be useful for the battery manufacturers to improve their extended producer responsibility and support responsible consumption and production.

Multi-functional metasurface as a transmissive/reflective FSS and an on-air frequency mixer

In this paper, a multi-functional metasurface is proposed, which can work as a narrowband transmissive/reflective frequency selective surface (FSS) and an on-air frequency mixer based on its switching response. The metasurface is made up of unit cells with square and circular metallic loops connected by PIN diodes controlled by a bias source. In contrast to typical wideband FSSs, the structure provides 0.55 GHz of narrow stopband (a fractional bandwidth of 22%) at 2 GHz in the OFF state bias. The bandstop response can be adjusted by varying the reverse bias voltage. The metasurface alternates between its functionalities when in forward bias by providing a passband at the operational frequency. The structure is compact and operates as a transmissive/reflective surface under two different bias conditions (ON and OFF). The design is angularly stable and polarization-insensitive for both TE and TM polarisation. A prototype of the designed structure is developed and the measured results correlate well with the simulated responses from the finite-difference time-domain (FDTD) method-based simulation of the circuit model. On-air frequency mixing for a wave propagating through the metasurface is demonstrated and the effects of different parameters affecting the mixing are parametrically studied through FDTD simulations and experiments.

A Review of the Information Technology and Operational Technology Convergence Using Internet of Things within the Circular Economy

Abstract The historical separation of Information Technology and Operational Technology in organizations, particularly in the industrial sector, is being challenged by the digital transformation. This shift towards a converged platform is driven by technological advancements, market pressures, and environmental and regulatory considerations. This paper explores the convergence of Information Technology and Operational Technology through the Internet of Things within the Circular Economy. A comprehensive overview of the current scientific literature is provided using a systematic review method. Initially, the evolving landscape of the Information Technology and Operational Technology integration is reviewed, then Internet of Things and Circular Economy are presented. The findings of this study include the challenges of the converged solution implementation, such as the technical integration complexities, cybersecurity risks, organizational and cultural barriers, and workforce skills gap. Furthermore, the role of the Internet of Things is demonstrated using novel smart circular loops, products, and applications showcasing innovative ideas such as product-as-a-service models, digital circular practices, products with embedded sensors, energy harvesting, and modular and upgrade capabilities as well as novel digital factory use cases such as smart manufacturing and industrial symbiosis networks. The key findings also outline the best practices and recommendations for a successful implementation of this converged infrastructure, highlighting the importance of a strategic implementation and cross-domain collaboration to achieve operational efficiency and environmental sustainability. The insights provided in this paper are valuable for academics, practitioners, and policymakers aimed to understand and harness the digital technologies for advancing sustainable practices towards a smart circular economy.

Mutual inductance between an infinite solenoid and a surrounding loop—A paradox resolved

Students may calculate the mutual inductance between an infinite solenoid and a surrounding circular loop using an incorrect method that yields the correct answer, causing frustration and confusion. A physical explanation for the agreement of the two methods is provided that is based on the translational symmetry of the solenoid. As a consequence, the conclusion generalizes to infinite uniform solenoids of arbitrary cross section.

Ar-ion- and electron-irradiated ZrC layers in ZrC-SiC-coated surrogate TRISO fuel particles

Surrogate tristructural isotropic (TRISO) particles, including ZrC and SiC layers, were manufactured through fluidized-bed chemical vapor deposition and irradiated. ZrC layers exhibited C/Zr atomic ratio of 0.95 without distinct crevices at interfaces in microscopy, but underwent significant microstructural changes post-irradiation. Defects included black dots and Frank loops, with increasing irradiation doses augmenting their area fractions. Frank loop density reduced at 9.4dpa due to the formation of fewer, fully circular loops. The ZrC hardness and modulus rose by 25% and 26% following Ar-ion irradiation at 9.4dpa, linked to the formed defects and implanted Ar ions. Electron irradiation expanded the defect-prone zone up to 100nm from the ZrC grain boundary and led to ZrO2 formation. ZrC grains recrystallized post electron irradiation at 700 °C, causing initial grain decomposition, amorphization, and nanocrystal formation. These nanocrystals, formed at 3.3dpa, closely aligned with ZrC diffraction patterns with no preferred orientations.

Radiation of twisted waves from a phased array of loop antennas in a resonant magnetoplasma

A study is made of the radiation from a phased array of circular loop antennas in a resonant magnetoplasma. The loops are assumed to have a finite radius and be located on a circumference in such a manner that their axes are aligned with a static magnetic field superimposed on the plasma. The emphasis is placed on determining the total radiated power of such an array and the partial powers going to different azimuthal field harmonics. For these quantities, rigorous integral representations are obtained using an expansion of the excited field in terms of cylindrical vector eigenfunctions of a magnetized plasma medium. Numerical results are reported for the radiation characteristics of the phased array in the whistler frequency range under conditions of the Earth's ionosphere. It is shown that an appropriately phased array is capable of selectively exciting waves with the desired helicity of the phase front and can be useful as a source of twisted whistler-mode waves in a magnetoplasma.

Predictors of Success for Pulmonary Vein Isolation With Pulsed-field Ablation Using a Variable-loop Catheter With 3D Mapping Integration: Complete 12-month Outcomes From inspIRE.

We previously presented the safety and early efficacy of the inspIRE study (Study for Treatment of Paroxysmal Atrial Fibrillation [PAF] by Pulsed-field Ablation [PFA] System With Irreversible Electroporation [IRE]). With the study's conclusion, we report the outcomes of the full pivotal study cohort, with an additional analysis of predictors of success. InspIRE was a prospective, multicenter, single-arm clinical trial of drug-refractory paroxysmal atrial fibrillation. Pulmonary vein isolation was performed with a variable-loop circular catheter integrated with a 3-dimensional mapping system. Follow-up with 24-hour Holter was at 3, 6, and 12 months, as well as remote rhythm monitoring: weekly from 3 to 5 months, monthly from 6 to 12 months, and for symptoms. The primary effectiveness end point (PEE) was acute pulmonary vein isolation plus freedom from any atrial arrhythmia at 12 months. Additional subanalyses report predictors of PEE success. The patient cohort included 186 patients: aged 59±10 years, female 30%, and CHA2DS2-VASc 1.3±1.2. The previously reported primary adverse event rate was 0%. One serious procedure-related adverse event, urinary retention, was reported. The PEE was achieved in 75.6% (95% CI, 69.5%-81.8%). The clinical success of freedom from symptomatic recurrence was 81.7% (95% CI, 76.1%-87.2%). Simulating a monitoring method used in standard real-world practice (without protocol-driven remote rhythm monitoring), this translates to a freedom from all and symptomatic recurrence of 85.8% (95% CI, 80.8%-90.9%) or 94.0% (95% CI, 90.6%-97.5%), respectively. Multivariate analyses revealed that left ventricular ejection fraction ≥60% (adjusted odds ratio, 0.30) and patients receiving ≥48 PFA applications (adjusted odds ratio, 0.28) were independent predictors of PEE success. Moreover, PEE success was 79.2% in patients who received ≥12 PFA applications per vein compared with 57.1% in patients receiving fewer PFA applications. The inspIRE study confirms the safety and effectiveness of pulmonary vein isolation using the novel 3-dimensional mapping integrated circular loop catheter. An optimal number of PFA applications (≥48 total or ≥12 per vein) resulted in an improved 1-year success rate of ≈80%. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04524364.

Simple Method for Re-tightening IMF Wires without Breakage.

This clinical technique aims to retighten intermaxillary fixation (IMF) wires when loosened intra/postoperatively. Intermaxillary fixation is one of the most important steps to obtain stable and functional occlusion in maxillofacial trauma. However, IMF wires tend to loosen over time. This loosened wire is generally removed and a new wire is used for IMF. Removal and refixation is time-consuming for surgeon and unconformable for the patient. We recommend a simple technique for re-tightening IMF wires without breakage, with the use of shepherd's crook explorer by making a small circular loop. This technique of re-tightening by looping further stretches and tightens the wire to regain stabilized occlusion with maximal intercuspation. This technique eliminates the need for removal and refixation of IMF wires, thereby improving patient comfort, yet obtaining stable occlusion over a long period of time. How to cite this article: Madhu SK, Dominic S, Baptist J, et al. Simple Method for Re-tightening IMF Wires without Breakage. J Contemp Dent Pract 2024;25(3):289-291.

Four-dimensional \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{N}$$\\end{document} = 2 superconformal long circular quivers

We study four-dimensional \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{N}$$\\end{document} = 2 superconformal circular, cyclic symmetric quiver theories which are planar equivalent to \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal{N}$$\\end{document} = 4 super Yang-Mills. We use localization to compute nonplanar corrections to the free energy and the circular half-BPS Wilson loop in these theories for an arbitrary number of nodes, and examine their behaviour in the limit of long quivers. Exploiting the relationship between the localization quiver matrix integrals and an integrable Bessel operator, we find a closed-form expression for the leading nonplanar correction to both observables in the limit when the number of nodes and ’t Hooft coupling become large. We demonstrate that it has different asymptotic behaviour depending on how the two parameters are compared, and interpret this behaviour in terms of properties of a lattice model defined on the quiver diagram.

Crossed arm-based quad T-shaped metallic arm with a circular loop resonator with wider bandwidth for high-frequency-based wireless communication

Crossed arm-based quad T-shaped metallic arm with a circular loop resonator with wider bandwidth for high-frequency-based wireless communication

On-Chip Circularly Polarized Circular Loop Antennas Utilizing 4H-SiC and GaAs Substrates in the Q/V Band.

This paper presents a comprehensive assessment of the performance of on-chip circularly polarized (CP) circular loop antennas that have been designed and fabricated to operate in the Q/V frequency band. The proposed antenna design incorporates two concentric loops, with the outer loop as the active element and the inner loop enhancing the CP bandwidth. The study utilizes gallium arsenide (GaAs) and silicon carbide (4H-SiC) semiconductor wafer substrates. The measured results highlight the successful achievement of impedance matching at 40 GHz and 44 GHz for the 4H-SiC and GaAs substrates, respectively. Furthermore, both cases yield an axial ratio (AR) of less than 3 dB, with variations in bandwidths and frequency bands contingent upon the dielectric constant of the respective substrate material. Moreover, the outcomes confirm that utilizing 4H-SiC substrates results in a significantly higher radiation efficiency of 95%, owing to lower substrate losses. In pursuit of these findings, a 4-element circularly polarized loop array antenna has been fabricated for operation at 40 GHz, employing a 4H-SiC wafer as a low-loss substrate. The results underscore the antenna's remarkable performance, exemplified by a broadside gain of approximately 9.7 dBic and a total efficiency of circa 92%. A close agreement has been achieved between simulated and measured results.

The Circular Current Loop as a Model of Fundamental Particles

The Circular Current Loop as a Model of Fundamental Particles

Transient Magnetic Shielding of a Planar Conductive Screen in the Presence of a Parallel Circular Loop Carrying Pulsed Current

Transient Magnetic Shielding of a Planar Conductive Screen in the Presence of a Parallel Circular Loop Carrying Pulsed Current

Exact Expressions for the Near Field of a Thin Uniform Circular Loop Current with Application to Loops Lying on a Half Space

Exact Expressions for the Near Field of a Thin Uniform Circular Loop Current with Application to Loops Lying on a Half Space

Magnetostatic Simulation and Design of Novel Radiofrequency Coils Based on Transverse Field Current Elements for Magnetic Resonance Applications.

Radiofrequency (RF) coils are key components in Magnetic Resonance (MR) systems and can be categorized into volume and surface coils according to their shapes. Volume RF coils can generate a uniform field in a large central sample's region, while surface RF coils, usually smaller than volume coils, typically have a higher Signal-to-Noise Ratio (SNR) in a reduced Region Of Interest (ROI) close to the coil plane but a relatively poorer field homogeneity. Circular and square loops are the simplest and most used design for developing axial field surface RF coils. However, for specific MR applications, the use of dedicated transverse field RF coils can be necessary or advantageous. Building on a previously developed and validated RF coil simulator, based on the magnetostatic approach, here we explore the potential applications of novel multiple axial field and transverse field surface RF coils in non-standard configurations. We demonstrate via numerical simulations that simple volume RF coils, matching a Helmholtz-like design, can be built with two identical transverse field RF coils separated by a given distance. Following well-known principles, the SNR of such novel configurations can be improved by a factor of up to √2 by combining two 90° rotated coils, producing, inside a central ROI, a circularly polarized B1 field.