Simple Arc Research Articles

A Circular Shape Arc Slot Ultra-Wideband Antenna for Biomedical Applications

In modern communication systems, ultra-wideband (UWB) technology has garnered substantial attention due to its superior attributes compared to traditional narrowband communication systems. Over the past decade, UWB technology has also found applications in microwave-based imaging systems. This study introduces a simple planar coplanar waveguide-fed circular shape arc slot antenna designed specifically for biomedicine and microwave medical imaging applications. The proposed design is implemented on a 1.6-mm-thick FR4 substrate with a relative permittivity of 4.4 and a loss tangent of 0.0009. The antenna has physical dimensions of 26 mm × 29 mm and achieves an impressive bandwidth of 16.6 GHz, spanning 2.4 to 19 GHz. It exhibits a peak gain of 2.5 dBi and consistent omnidirectional radiation characteristics. Thorough temporal analysis validates the antenna's performance within acceptable limits, which is further affirmed through practical fabrication and testing, demonstrating strong agreement with simulation results.

Computational analysis of piston shape effects on in-cylinder gas flow, fuel-charge mixing, and combustion characteristics in a two-stroke rod-less spark ignition opposed-pistons engine

Compared with the traditional in-cylinder direct-injection spark ignition engine, the side-injection and side-spark-ignition characteristics of the two-stroke opposed-piston engine increase the ignition kernel offset and flame propagation distance. Increasing the flame propagation speed can to some extent solve the drawbacks caused by the non-central arrangement of spark plugs. The combustion chamber structure plays a crucial role in gas flow, fuel-charge mixing, and combustion characteristics. Therefore, three pistons were designed and comparatively analyzed in this study. The results show that: The pancake piston is beneficial to maintaining the intake swirl strength due to its simple and smooth spherical arc structure. The swirl strength of the pit and pit-guided piston decreases obviously, and the tumble strength can be maintained well. Compared to pancake and pit-guided pistons, the average TKE for the pit piston increased by approximately 25%, with a more concentrated distribution at the spark timing. The pancake piston exhibits the best scavenging performance, reducing the residual exhaust gas ratio by 2.1% and fresh air loss by 3.3% to the pit piston. A stable ignition core can be formed at the spark timing, but significant differences are observed in the flame propagation process for three pistons. Compared to the pit-guided piston, the pit piston has a 0.3% decrease in the indicated thermal efficiency, but a 13.1% decrease in combustion duration, which reduces knock tendency.

A Numerical Analysis on the Performance and Optimization of the Savonius Wind Turbine for Agricultural Use

Given the state of the world nowadays, renewable energy is becoming more and more essential rendering wind turbine electricity quite important. Its shape and the fact that the Savonius vertical axis wind turbine runs at relatively low wind speeds with high torque values makes it suitable for practical uses such as that of an irrigation system in agriculture industry. This paper utilizes numerical research with Computational Fluid Dynamics (CFD) to investigate the performance of a vertical-axis wind turbine. The ANSYS CFD program was engaged to construct the simulations during the pre- and post-processing stages. Wind speed remained constant while the angular velocity was altered to enable analysis of the flow through the wind turbine. Because of its mechanical simplicity, the primary profile of a semicircle has remained a typical option for turbines that generate high torque based on drag force. The effects of using elliptical curves and the fluctuation in thickness along the profile chord were both examined in this study. Equivalently, an attempt to optimize the rotor's design was made. After the performance of a numerical simulation, a geometry consisting of simple circle arcs was developed, with a 10.9% improvement in the power coefficient, analogous to prior optimizations with more complicated geometries. The numerical results derived include the torque coefficient evolution throughout a full rotation as well as the distribution of vorticity magnitude at different rotor points.

Structural studies, dielectric and electrical properties of (1-x) Pb(Zr0.52Ti0.48)O3– xCoFe2O4 multiferroics materials

This work aimed to develop a better combination of PbZr0.52Ti0.48O3 (PZT) and CoFe2O4 (CFO) ceramics with enhanced structural, dielectric, and electric properties. For this aim, (1-x)PZT-xCFO nanocomposites at (0.00, 0.10, 0.20, 0.30, 0.40, 0.50, and 1.00) were synthesized using the combination before calcination of sol–gel (for PZT ceramic) and solid-state (for CFO material) methods. The powder X-ray diffraction analysis reveals that the CFO crystallizes in a spinel cubic structure with the Fd3m space group structure, while the PZT compound crystallizes in two tetragonal and rhombohedral structures with P4mm and R3m space groups respectively, which is confirmed by Raman spectra which also demonstrate that CFO content in (1-x)PZT-xCFO composites affects the vibration types. The scanning electron micrographs (SEM) show that the grains are homogeneous and irregular, with several pores on the surface of ceramics. The dielectric properties of the ceramics were investigated as a function of temperature (from 25 to 500 °C) and frequency (from 100 Hz to 2 MHz) using complex impedance spectroscopy. It shows that with the increase of CFO ratio, the dielectric permittivity values increase in the composites until the composition corresponding to x = 0.3 From 485 to 1620 at 5KHz) and then decreases until 65 for x = 1.00. The dielectric constant a function of frequency at different temperatures of (1-x)CFO-xPZT composites indicated that the dielectric constant increases with the increase of CFO content. The impedance spectrum is characterized by simple semicircular arcs and shows a non-Debye relaxation. The electric conductivity reveals that as CFO increases, conductivity remains constant, and the frequency dependence of conductivity shifts away from high frequencies. Also, the value of the exponent n decreases from 1.44 to 0.26 with an increasing CFO concentration. The activation energy is between 0.32 and 0.16 which confirms that electron hopping is responsible for electrical conduction.

The vestibular system: Contributions of Lorente de Nó.

Rafael Lorente de Nó was a neuroscientist that worked alongside two of the giants of Medicine, the Nobel Prize winners Cajal and Bárány. To describe the contributions of Lorente de Nó to vestibular neuroscience. Detailed review of the publications of Lorente de Nó and analysis of the archives from Junta para Ampliación de Estudios e Investigaciones Científicas at Residencia de Estudiantes (Madrid, Spain), Casa de Salud Valdecilla at Hospital Universitario Marqués de Valdecilla (Santander, Spain), Becker Medical Library at Washington University (St. Louis, MO, USA), Rockefeller Archive Center (Sleepy Hollow, New York, NY, USA), Archivo Fernando de Castro (Madrid, Spain), Biblioteca Nacional de España (Madrid, Spain) and Legado Cajal at Instituto Cajal (Madrid, Spain). Most of this material is unpublished and includes over a hundred letters to or from Lorente. Lorente de Nó made a substantial contribution to our understanding of the vestibular system. Amongst these, he meticulously detailed the course of the vestibular nerve and its central projections. He described the vestibulo-ocular reflex as the consequence of an integration of the various nuclei and connections across the vestibular system, rather than a simple three-neuron arc. He also highlighted the role of the reticular formation in the generation of the fast phase of the nystagmus. Lorente de Nó was a pioneer of modern neuro-otology, having made outstanding contributions to vestibular neuroscience, forging novel discoveries that still burn true today.

MONITORING OF THE COASTAL DYNAMICS ON THE SAND SPIT AT TORTUGUEROS BEACH, MEXICO

Sand spits occur worldwide in different shapes, from a single, relatively simple arc to an irregular, crenulated, and complex barrier. Cross-shore and longshore sediment transport often influence spit dynamics (Nagarajan et al., 2015), strongly linked to wave energy and sediment supply. The present analysis focuses on a dynamic and complex spit at Tortugueros beach, a re-entrant bay, 1 km in length, on the Gulf of Mexico. Tortugueros beach is a wave-dominated beach with very fine to fine sand that forms a fairly gentle sloping beach profile. The sediment sources are longshore sediment transport and onshore sandbar migration, while sediment loss is due to long- and cross shore (during storms) transport. The region is micro-tidal, with mean and maximum high tide levels of 0.18 m and 0.92 m above the mean sea level. Given the high dynamics of the Tortugueros beach spit system and the lack of data measured on the beach, a monitoring system was developed to collect field data regularly to help us improve the understanding of the functioning of the coast on this beach, and the international knowledge related to the formation and morphological evolution of this type of spits in other similar beaches around the world.

Latest Developments in TIG Welding - A Review

Abstract: TIG welding has been used to join two metals or alloys by continuously providing a wire electrode and a shielding gas to protect the weld pool from air contamination. The supply of inert shielding gas offers a number of benefits over other conventional methods of fusing the metals using simple arc welding procedures. A few benefits of this welding method include improved tensile strength, finer grain hardness, excellent weld quality and appearance, microstructure improvement, and metallurgical properties over the source metal. In order to shed light on those sectors that have not yet realised their full potential, the primary objective of this research is to assess current advances in the TIG welding business. Thus, based on tests, parameters, and the kinds of materials used for welding, numerous TIG welding tales are compiled and investigated in this study article. The bulk of the mentioned studies state that the main parameter among them was found to be current, however gas flow rate and angle of weld utilising modern techniques have not been used up to that point. Based on the study, some recommendations for the manufacturing sectors are included below, which might be useful for future industrial applications.

Modelling a simple arc shaped gold coated PCF-based SPR sensor

Modelling a simple arc shaped gold coated PCF-based SPR sensor

Highly Sensitive, Robust, and Recyclable TiO2/AgNP Substrate for SERS Detection.

Label-free biosensors provide an important platform for detecting chemical and biological substances without needing extra labeling agents. Unlike surface-based techniques such as surface plasmon resonance (SPR), interference, and ellipsometry, surface-enhanced Raman spectroscopy (SERS) possesses the advantage of monitoring analytes both on surfaces and in solutions. Increasing the SERS enhancement is crucial to preparing high-quality substrates without quickly losing their stability, sensitivity, and repeatability. However, fabrication methods based on wet chemistry, nanoimprint lithography, spark discharge, and laser ablation have drawbacks of waste of time, complicated processes, or nonreproducibility in surface topography. This study reports the preparation of recyclable TiO2/Ag nanoparticle (AgNP) substrates by using simple arc ion plating and direct-current (dc) magnetron sputtering technologies. The deposited anatase-phased TiO2 ensured the photocatalytic degradation of analytes. By measuring the Raman spectra of rhodamine 6G (R6G) in titrated concentrations, a limit of detection (LOD) of 10−8 M and a SERS enhancement factor (EF) of 1.01 × 109 were attained. Self-cleaning was performed via UV irradiation, and recyclability was achieved after at least five cycles of detection and degradation. The proposed TiO2/AgNP substrates have the potential to serve as eco-friendly SERS enhancers for label-free detection of various chemical and biological substances.

On the smallest convex cover of a simple arc of space-curve

On the smallest convex cover of a simple arc of space-curve

Enumerating Nontrivial Knot Mosaics with SAT (Student Abstract)

Mathematical knots are interesting topological objects. Using simple arcs, lines, and crossings drawn on eleven possible tiles, knot mosaics are a representation of knots on a mosaic board. Our contribution is using SAT solvers as a tool for enumerating nontrivial knot mosaics. By encoding constraints for local knot mosaic properties, we computationally reduce the search space by factors of up to 6600. Our future research directions include encoding constraints for global properties and using parallel SAT techniques to attack larger boards.

Neural Reflex Networks for Automating Quadcopter Drone Obstacle Avoidance

The physically modelled neural and nervous networks pioneered more than two decades ago by Mark Tilden, E. A. Rietman and collaborators, M. Ashkenazi et al. have proven to be a robust and interesting way to obtain powerful emergent behavior by utilizing neuromimetic circuitry. Using a physical representation of biologic neurons, both motor (NU) and cortical (NV) these structures mimic simple reflex arcs present in a large number of evolved organisms. The simple circuits using logic gate oscillators wired as integrators or pulse delay loops with sensors coupled as current injectors or variable resistors of different types demonstrated unexpected emergent „survival” behaviors when connected in chains or loops of several neurons. Mark Tilden calls the simplest functional unit of such looped structures „bicores”-as two neurons linked together in a loop already generate meaningful behavior when their inputs are linked to appropriate sensors. These powerful neuromimetic machines allow for a robust implementation of automated responses in autonomous or semi-autonomous robots. Quadcopters are a very good target for neural network control/stabilization because of their unique flight dynamics and normal control procedures. Obstacle avoidance and stabilization are simple tasks for a well-tuned physical neural network.

Performance assessment of innovative concave type shear connector in a composite structure subjected to push-out loading

The use of shear connectors in steel beams with reinforced concrete (RCC) slabs has increased in favor in the past few decades as it is advantageous for quick, simple, and cost-effective composite construction. The current study proposes an innovative concave type shear connector for the composite steel beams-RCC structure in buildings and bridges. Installation of headed shear connectors requires gun welding, which is costly and not readily available for small-scale works. In contrast, the novel concave shear connector developed can be economically installed using a simple arc welding technique by bending rebars readily available on site. Its performance was evaluated through numerical analysis. Nonlinear finite element (F.E.) analysis using ABAQUS software was performed on the push-out test of the shear connector using Eurocode 4 specification guidelines. For the effectiveness of shear connectors in the composite systems, the performance of the concave shear connector was compared with the 19 mm standard headed stud shear connectors. The main outputs were the load-slip characteristics like the ultimate slip and ductility, stiffness, and shear strength in the composite steel beams-RCC slab structure. The results indicate that concave type shear connectors offer 2.5 times higher stiffness and 20% connector material savings having identical shear strength compared to 19 mm diameter headed stud. Moreover, although the slip of the concave type shear connector was less than 19 mm headed stud, satisfying 6 mm ductility criteria as per Eurocode 4 specific guidelines.

Geochronology, geochemistry and tectonic implications of early Carboniferous plutons in the southwestern Alxa Block

AbstractThe southeastern Central Asian Orogenic Belt (CAOB) records the assembly process between several micro-continental blocks and the North China Craton (NCC), with the consumption of the Paleo-Asian Ocean (PAO), but whether the S-wards subduction of the PAO beneath the northern NCC was ongoing during Carboniferous–Permian time is still being debated. A key issue to resolve this controversy is whether the Carboniferous magmatism in the northern NCC was continental arc magmatism. The Alxa Block is the western segment of the northern NCC and contiguous to the southeastern CAOB, and their Carboniferous–Permian magmatism could have occurred in similar tectonic settings. In this contribution, new zircon U–Pb ages, elemental geochemistry and Sr–Nd isotopic analyses are presented for three early Carboniferous granitic plutons in the southwestern Alxa Block. Two newly identified aluminous A-type granites, an alkali-feldspar granite (331.6 ± 1.6 Ma) and a monzogranite (331.8 ± 1.7 Ma), exhibit juvenile and radiogenic Sr–Nd isotopic features, respectively. Although a granodiorite (326.2 ± 6.6 Ma) is characterized by high Sr/Y ratios (97.4–139.9), which is generally treated as an adikitic feature, this sample has highly radiogenic Sr–Nd isotopes and displays significantly higher K2O/Na2O ratios than typical adakites. These three granites were probably derived from the partial melting of Precambrian continental crustal sources heated by upwelling asthenosphere in lithospheric extensional setting. Regionally, both the Alxa Block and the southeastern CAOB are characterized by the formation of early Carboniferous extension-related magmatic rocks but lack coeval sedimentary deposits, suggesting a uniform lithospheric extensional setting rather than a simple continental arc.

Designing Robust and Automated Treatment Plans Utilizing Dynamic Couch Motion With Automated Treatment Planning: Delivering Dose to a New Dimension ― Part B

<h3>Purpose/Objective(s)</h3> To develop a novel treatment technique, with automated treatment planning, that will yield superior dose distribution with dynamic couch motion at static gantry positions. <h3>Materials/Methods</h3> Modern treatment planning systems (TPS) cannot design, calculate, or optimize treatment plans utilizing continuous couch-based delivery. Based on the current limitation of modern TPS, the need to plan dynamic couch-based dose delivery arises for our investigation. We implement an automatic method utilizing the TPS scripting application programming interface (ESAPI). Additionally, we introduce a novel gantry static couch motion technique (GsCM) with static gantry positions and dynamic couch motion for brain treatment. The script interface allows selection of PTV, adding MLCs and PTV margin, choosing the number of fields, and initiation of the dose calculation within the TPS environment. We can automatically design custom treatment plans with simple 3-dimentional (3D) planning and conformal arc. This script based automated planning was retrospectively applied to brain patients (n = 5) using 200 cGy for 23 fractions. Initial development required implementing a conversion from the TPS mechanical axes to that of the machine. The readable Extensible markup language (XML) files are generated in the TPS environment using ESAPI by combining the fields at each couch position into a single deliverable field for each gantry angle utilizing continuous couch motion. The entire workflow is feasible within our script interface. The last part of this study focused on verifying the dose delivery. We used an ion chamber array positioned in the vertical direction to avoid side beam entrance. Trajectory log files were also analyzed using root mean square error (RMSE) to verify the MLC, gantry, and couch position accuracy. <h3>Results</h3> All treatment plans satisfy the criteria of V100% ≥ 95% and respect the dose to organs-at-risk (OARs). Automated script-based plans took less than a minute (excluding dose calculation) to design as compared to manual planning (2-8 hours per plan). The delivery was found to be less than 2 minutes for two 90 degrees partial arcs as compared to field-by-field delivery (15-30 minutes based on the plan type). All script-based plans (n = 5) passed patient-specific QA (> 95%) using the criteria of 2 mm distance to agreement and 2% dose difference. The couch rotational RMSE error for step and shoot and continuous delivery was 0.1 degrees and 0.12 degrees, respectively. MLC RMSE was 0.005 mm, and 0.006 mm for step and shoot and continuous delivery. <h3>Conclusion</h3> The results of our study indicate that the automated custom planning with couch motion is feasible and comparable with clinical planning in terms of dosimetric quality. The developed methodology provides a tool that is integratable with the current TPS without any additional resources. It designs script-based plans for dynamic couch motion-based dose delivery.

On the existence of four or more curved foldings with common creases and crease patterns

Consider an oriented curve Gamma in a domain D in the plane {varvec{R}}^2. Thinking of D as a piece of paper, one can make a curved folding in the Euclidean space {varvec{R}}^3. This can be expressed as the image of an “origami map” Phi :Drightarrow {varvec{R}}^3 such that Gamma is the singular set of Phi , the word “origami” coming from the Japanese term for paper folding. We call the singular set image C:=Phi (Gamma ) the crease of Phi and the singular set Gamma the crease pattern of Phi . We are interested in the number of origami maps whose creases and crease patterns are C and Gamma , respectively. Two such possibilities have been known. In the authors’ previous work, two other new possibilities and an explicit example with four such non-congruent distinct curved foldings were established. In this paper, we determine the possible values for the number N of congruence classes of curved foldings with the same crease and crease pattern. As a consequence, if C is a non-closed simple arc, then N=4 if and only if both Gamma and C do not admit any symmetries. On the other hand, when C is a closed curve, there are infinitely many distinct possibilities for curved foldings with the same crease and crease pattern, in general.

Rapid Characterization of Polymer Materials Using Arc Plasma-Based Dissociation-Mass Spectrometry

Fingerprinting spectra of polymer materials containing information of monomers' molecular weight and detailed structure, constituents, and sequences were obtained by a direct analytical process using arc plasma-based dissociation (APD)-mass spectrometry. The thermal arc plasma generated using a simple arc discharge device induces the dissociation of the polymeric backbone, producing mass spectra with strong regularity within seconds. The molecular weight of the repeating unit was revealed by equal intervals between peak series and protonated monomer ions in the mass spectra. Meanwhile, lots of secondary fragment ions were produced to provide abundant structural information. For polyethers, it is even possible to decipher (read) the "sequence" directly from their spectra. Polymers composed of isomers or only differing in their initiator moieties were easily distinguished with their characteristic APD mass spectra. The spectra were highly reproducible according to the results of similarity calculation. Unlike pyrolysis mass spectrometry, in the APD device, polymers in liquid, solid, powder, and crude samples can be analyzed directly without any pretreatment, and the regular spectra are easier to interpret. Compared with other direct analytical methods, more structural informative spectra can be acquired owing to the high energy, high temperature, and unique chemical reactivity of arc plasma. Thus, this technique is promising to be a valuable tool in rapid elucidation of polymer materials.

Comprehensive nodal breast VMAT: solving the low-dose wash dilemma using an iterative knowledge-based radiotherapy planning solution.

IntroductionAimed to develop a simple and robust volumetric modulated arc radiotherapy (VMAT) solution for comprehensive lymph node (CLN) breast cancer without increase in low‐dose wash.MethodsForty CLN‐breast patient data sets were utilised to develop a knowledge‐based planning (KBP) VMAT model, which limits low‐dose wash using iterative learning and base‐tangential methods as benchmark. Another twenty data sets were employed to validate the model comparing KBP‐generated ipsilateral VMAT (ipsi‐VMAT) plans against the benchmarked hybrid (h)‐VMAT (departmental standard) and bowtie‐VMAT (published best practice) methods. Planning target volume (PTV), conformity/homogeneity index (CI/HI), organ‐at‐risk (OAR), remaining‐volume‐at‐risk (RVR) and blinded radiation oncologist (RO) plan preference were evaluated.ResultsIpsi‐ and bowtie‐VMAT plans were dosimetrically equivalent, achieving greater nodal target coverage (P < 0.05) compared to h‐VMAT with minor reduction in breast coverage. CI was enhanced for a small reduction in breast HI with improved dose sparing to ipsilateral‐lung and humeral head (P < 0.05) at immaterial expense to spinal cord. Significantly, low‐dose wash to OARs and RVR were comparable between all plan types demonstrating a simple VMAT class solution robust to patient‐specific anatomic variation can be applied to CLN breast without need for complex beam modification (hybrid plans, avoidance sectors or other). This result was supported by blinded RO review.ConclusionsA simple and robust ipsilateral VMAT class solution for CLN breast generated using iterative KBP modelling can achieve clinically acceptable target coverage and OAR sparing without unwanted increase in low‐dose wash associated with increased second malignancy risk.

Simulation study of influence of the outlet elastic baffle on pressure in arc chamber during the interrupting process of low-voltage circuit breaker

In this paper, a bidirectional fluid–solid interaction method is established to investigate the influence of the outlet elastic baffle on the pressure in the arc chamber in the breaking process of a low-voltage circuit breaker. Based on the computational fluid dynamic method, the flow model in the arc chamber is established. The model of the outlet baffle, with consideration of the nonlinear behavior, is established by the finite element method. By introducing dynamic grid technology, the interaction process of deformation of the outlet baffle and arc chamber pressure can be analyzed. A simple arc extinguishing chamber with an outlet baffle is designed, and experiments with a LC oscillating circuit are carried out. By using a high-speed camera and a pressure sensor, the deformation of the baffle and the pressure of the arc chamber are measured in the breaking process. The simulation model is verified by experimental results. It is worth noting that the flutter behavior of the elastic baffle was observed in the experiments and in the numerical simulation. Through simulation analysis, it is found that the flutter behavior is caused by the first-order mode of the elastic baffle under the excitation of arc chamber pressure.

Z-arcs in the thirty degrees sector

Abstract In this detailed study of 3-segment non-convex simple arcs inscribed in the 30 ∘ {30^{\circ}} sector, we show that each such arc of length one fits in the interior of the sector of radius one with the prescribed embedding. We discuss implications of this study for covering problems involving triangular covers and for the worm problem of Leo Moser.