Shape Of Conductor Research Articles

Novel Slot-MIMO Antenna Approach for Improved Connectivity in Sub-6 GHz Applications

This paper presents a proposed Slot-MIMO antenna with two identical ports, each port is fed through 50-Ohm microstrip line to operate within the sub-6 GHz (3.5-4.5 GHz) for fifth-generation (5G) cellular phone applications. The proposed MIMO antenna has been designed on FR-4 dielectric substrate (ɛ = 4.4, δ = 0.025, and h = 1.6 mm). The ground has two basic slots, one square slot radiator, and one irregular square slot radiator filled with a Diamond conductor shape. In addition, the ground has a DGS structure (8-slots) beside the two basic slots. The ground DGS is used to adjust the resonance frequency as well as to reduce the mutual coupling between the ports. The simulated result indicated that the proposed MIMO antenna has a gain of about 2.5 dBi and an impedance bandwidth of 614 MHz at the -10-dB (3.751-4.365 GHz). However, an impedance bandwidth of 1180 MHz at -6-dB (3.32-4.5 GHz) is achieved. The mutual coupling is less than -24 dB overall the bandwidth, and the efficiency is more than 80% at the antenna resonance frequency (4.15 GHz). This antenna has been implemented and measured, and the results have been agreed with the simulated ones. In addition, the proposed Slot-MIMO antenna can be used as a MIMO antenna-cell with the smartphone. Many MIMO cells can be etched on the smartphone motherboard to improve connectivity with high isolation.

The use of a swept frequency alternating current potential difference method for identifying local geometric features within prismatic conductors

Potential difference methods are widely accepted as means to detect and monitor cracks in safety critical components. This paper investigates the capability of the potential difference method that uses a swept frequency alternating current excitation (i.e. skin effect with varying current penetration depths) in identifying conductor shapes and features through experiments and finite element analysis. The study focused on samples with the size of 55 mm × 100 mm2 and surface features with opening widths vary from 11% to 42% to the sample size. The method has been investigated by finite element analysis with the capability to distinguish cross-sectional shapes of non-magnetic conductors due to prominent current crowding on surfaces, in which the potential differences measured from a SS316 conductor of triangular cross-sectional shape are higher to those of a circular shape by 77% at 300 kHz. The detection capability of the method has also be confirmed, which is attributed to the impact of feature openings on skin effect. At 50 kHz, potential differences measured across features with the same cross-sectional area of 9 mm2 on EN1A samples rise by 130% as the opening width increase from 11% to 42% to the sample size.

A topology optimization of on-chip planar inductor based on evolutional on/off method and CMA-ES

PurposeThere are few reports that evolutional topology optimization methods are applied to the conductor geometry design problems. This paper aims to propose an evolutional topology optimization method is applied to the conductor design problems of an on-chip inductor model.Design/methodology/approachThis paper presents a topology optimization method for conductor shape designs. This method is based on the normalized Gaussian network-based evolutional on/off topology optimization method and the covariance matrix adaptation evolution strategy. As a target device, an on-chip planer inductor is used, and single- and multi-objective optimization problems are defined. These optimization problems are solved by the proposed method.FindingsThrough the single- and multi-objective optimizations of the on-chip inductor, it is shown that the conductor shapes of the inductor can be optimized based on the proposed methods.Originality/valueThe proposed topology optimization method is applicable to the conductor design problems in that the connectivity of the shapes is strongly required.

Near surface assessment of New capital city using geophysical techniques

ABSTRACT The Egyptian government announced the creation of a brand new capital city to address Cairo’s rapid population expansion and improve the quality of life for citizens, which is thought to have a strong demand for housing. In this study, we focused on the application of geophysical techniques, specifically Electrical Resistivity Tomography (ERT) and Very Low Frequency Electromagnetic Method (VLF-EM), to investigate the shallow subsurface in the New Capital city in Egypt. The study area is located in the eastern part of Cairo and is characterised by Oligocene and Miocene rocks. The ERT profiles reveal four geoelectrical layers based on resistivity values, with the first layer (Resistivity >300 Ω.m) interpreted as sand and conglomerate on the surface or basalt below. The second layer (100–300 Ω.m) is identified as sandstone, while the third layer (15–100 Ω.m) is interpreted as humid sandstone. The fourth layer (1–15 Ω.m) is characterised as shale. The abrupt changes in resistivity values horizontally indicate the probability of subsurface structures, including faults. The VLF-EM method is used to identify faults and cracks in the earth’s crust. The results provide information on the size, shape, and depth of both shallow and deep subterranean conductors. Anomalies of high conductivity suggest fault or fracture zones influencing underlying strata.

Refinement of Thermal Conduction-Based Dew Condensation Detection on Target Solid Surface by Galvanic Arrays Sensor Chip

ABSTRACT A reliable early detection of dew condensation can efficiently protect target solid surfaces from numerous negative effects such as surface fogging and corrosion. Achieving this goal beneficially requires a specially designed moisture sensor whose surface needs to be thermally identical with the target surface via a thermal conductor. However, the effect of the geometrical shape of the thermal conductor on the thermal conduction process is yet to be experimentally emphasized. In this study, we examined the potential detection of dew condensation events at our recently developed moisture sensor chip (MSC) under an effective control of its surface temperature via an attachment with Al-based thermal conductors. Precise and practical dew condensation detections were carried out in a multi-step and a one-step temperature-controlling modes, respectively. The experimental results revealed that the MSC response current (as a measure of dew condensation detection) increased when its surface temperature was dropped below the dew point. Moreover, the geometrical shape of thermal conductor attached to the backside of MSC can affect its thermal resistivity leading to a remarkable improvement in dew condensation detection. Therefore, it can be concluded that the geometrically designed thermal conductor can work effectively to minimize the temperature difference between MSC and target surface. This finding is believed to enable MSC to detect the target surface condition precisely in real time.

Design of Transfer Impedance Measurement Fixture of EMI Gaskets Up to 18 GHz

To achieve the transfer impedance measurement of electromagnetic interference (EMI) gaskets, a fixture useful up to 18 GHz is developed based on the SAE ARP1705C standard. The radial size of the coaxial section of the fixture is shaped from the perspective of its characteristic impedance and suppression of higher-order modes. Subsequently, a parametric analysis is performed to examine the sensitivity of critical dimensions, and the study analyzes the key factors affecting the voltage standing wave ratio (VSWR) of the fixture and its 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> resistor. Based on the preceding analysis, two solutions are proposed to improve the VSWR: reducing the length of the 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> resistor and modifying the shape of the coaxial outer conductor. The ultimate outcome of the transfer impedance measurement fixture yields a VSWR lower than 2.6:1, up to 18 GHz. The functionality of the fixture is demonstrated through the measurement of two gaskets, showcasing its practical utility in engineering applications.

Prediction and characterization of three-dimensional multi-mode coupled galloping of multi-span ice-accreted transmission conductors

This study presents a nonlinear analysis framework of three-dimensional galloping of multi-span ice-accreted transmission line conductors suspended by insulators. The vertical, lateral and torsional conductor displacements are described by modal displacements with mode shapes of single span conductors, and the insulators are modeled as pendulums. The aerodynamic forces on the conductor are modeled using quasi-steady theory. The linear equations of motion with respect to the static equilibrium are also derived. The analysis framework is applied to two- and three-span four-bundled ice-accreted transmission conductors with complex eigenvalue analysis and response history analysis. A harmonic balance approach is also proposed for a direct calculation of steady-state galloping response. The accuracy and efficiency of the proposed frameworks are verified using the results estimated from a finite element model. The similarities and differences of galloping characteristics, i.e., initiation condition, steady-state amplitude, dynamic tension, between single- and multi-span conductors are investigated. The role of suspension insulators on multi-span galloping is clarified. The longitudinal motions of insulators result in reduced vertical modal frequencies of conductor, thus lead to different galloping characters. The galloping of multi-span conductors with closely spaced modal frequencies can be initiated from multiple modal branches with a beating phenomenon.

Optimal Coil Design for Coreless Linear Motors Based on the Extended Stream-Function Method

This paper concerns a coil design technique for coreless linear motors that is based on the stream-function methodology. This method allows for the synthesis of the optimal conductor shape on a source surface based on constraints and objectives in an optimization problem. The method is extended to allow for motion and multi-phase commutation and is applied to the design of coils for coreless linear motors with concentrated and distributed winding configurations. A manufacturable conductor is extracted for a motor with a concentrated coil configuration. The resulting coil is compared to a traditional concentrated coil-set by a simulation of a coreless linear motor, in which the windings are produced using printed circuit board technology. It shows an increase in force production for the geometry with the conductor designed using the stream-function method, whereas the average temperatures in the coils of both geometries are identical.

Electromagnetic Imaging for Buried Conductors Using Deep Convolutional Neural Networks

In the past, many conventional algorithms, such as self-adaptive dynamic differential evolution and asynchronous particle swarm optimization, were used to reconstruct buried objects in the frequency domain; these were unfortunately time-consuming during the iterative, repeated computing process of the scattered field. Consequently, we propose an innovative deep convolutional neural network approach to solve the electromagnetic inverse scattering problem for buried conductors in this paper. Different shapes of conductors are buried in one half-space and the electromagnetic wave from the other half-space is incident. The shape of the conductor can be reconstructed promptly by inputting the received scattered fields measured from the upper half-space into the deep convolutional neural network module, which avoids the computational complexity of Green’s function for training. Numerical results show that the root mean square error for differently shaped—circular, elliptical, arrow, peanut, four-petal, and three-petal—reconstructed images are, respectively, 2.95%, 3.11%, 17.81%, 15.10%, 14.14%, and 15.24%. Briefly speaking, not only can circular and elliptical buried conductors be reconstructed; some irregular shapes can be reconstructed well. On the contrary, the reconstruction result by U-Net for buried objects is worse since it is not able to obtain a good preliminary image by processing only the upper scattered field—that is, rather than the full space. In other words, our proposed deep convolutional neural network can efficiently solve the electromagnetic inverse scattering problem of buried conductors and provide a novel method for the microwave imaging of the buried conductors. This is the first successful attempt at using deep convolutional neural networks for buried conductors in the frequency domain, which may be useful for practical applications in various fields such as the medical, military, or industrial fields, including magnetic resonance imaging, mine detection and clearance, non-destructive testing, gas or wire pipeline detection, etc.

Microwave Imaging for Half-Space Conductors Using the Whale Optimization Algorithm and the Spotted Hyena Optimizer

This research implements the whale optimization algorithm (WOA) and spotted hyena optimizer (SHO) in inverse scattering to regenerate the conductor shape concealed in the half-space. TM waves are irradiated from the other half-space to a perfect conductor with an unknown shape buried in one half-space. The scattered field measured outside the conductor surface with the boundary condition is used to reconstruct the object using the WOA and SHO algorithms. Several scenarios of reconstruction accuracy were compared for the WOA and SHO. The numerical simulations prove that the WOA has a better reconstruction capability.

Influence of the cross-sectional shape of conductors of multiconductor transmission lines on the accuracy of their parameters and characteristics calculation

Influence of the cross-sectional shape of conductors of multiconductor transmission lines on the accuracy of their parameters and characteristics calculation

Solution Algorithm and Experimental Verification on Behavior of Crossing Frame Impacted by Conductor Breaking

The problem that impact dynamics caused by conductor breakage is not considered in the design of the crossing frame appear at present. Therefore, the system dynamics solution algorithm of conductor impact crossing frame was established based on the Absolute Nodal Coordinate Formulation (ANCF). Taking the conductor test of free swing and free drop as an example, the correctness of the algorithm was verified. The results shown that the beam element was used to establish the system dynamic equations which was solved by Newmark method. Penalty function method was used to calculate the contact between conductor and hard sealing net pole of crossing frame. The test results indicated that the conductor was in curve bending state when the conductor impacted blocking pole, the conductor shape was in good agreement with the calculation results. The correctness of the algorithm was verified to a certain extent, which provided an effective theoretical basis for the design and calculation of the crossing frame based on the impact dynamic behavior of conductors.

Mechanical Analysis of Full-Scale Nb3Sn CICC Designs for Tokamaks

Several designs of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn Cable-In-Conduit Conductors (CICCs) have been proposed so far for high-performance tokamak magnets. The Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn strands composing the conductors are subjected to mechanical stresses of electromagnetic (EM) and thermal origin, inducing local deformations and affecting the strands critical current carrying capability. In the last ten years a numerical tool based on a finite element (FE) code has been developed to simulate the mechanical behavior of the CICCs subjected to operating loads. The main goal of this tool is to predict the electro-mechanical performance of the conductor in operation as a function of the design parameters such as the void fraction, the twist pitches and the conductor shape. In this work, a detailed model of a full-cable ITER TF CICC is presented. This model proves useful for a deeper understanding of the mechanical phenomena occurring among the sub-cables during the conductor operation. Moreover, the numerical modelling of different conductors from the ITER, DTT and JT60 projects is also presented to highlight the versatility of the code.

Comparison of AC Losses in the Winding of Electrical Machines with Fixed Strands Positions, Fixed Conductor Shapes and Random Winding

In high performance electric machines, the increase of fundamental frequency leads to additional losses in the winding due to parasitic effects such as the associated skin and proximity effects. In the first part, this paper presents an investigation into accurate modelling of AC losses in the winding using numerical methods and their experimental verification. Then, using experimental motorette setups, this research provides a comparative study between fixed strand positioning and fixed conductor shapes on the AC losses in the winding. It is shown that the exact position of strands in the conductor is not a critical factor; however, it is very important to control the conductor shape inside the slot. In the final section of this paper, an investigation into the relationship between AC losses in the winding and copper filling factor is presented. It is shown experimentally that counter-intuitive design choices such as using a lower copper fill factor and thicker strand diameters may be beneficial in achieving the highest overall efficiency.

The genus Lycosoides Lucas, 1846 in the Maghreb region, with the description of five new species (Araneae: Agelenidae)

North African species of the genus Lycosoides Lucas, 1846 are revised. Five new species are described: L. incisofemoralis Bosmans, sp. n. (♂♀) from Algeria, L. kabyliana Bosmans, sp. n. (♂♀) from Algeria, L. murphyorum Bosmans, sp. n. (♂♀) from Morocco, L. robertsi Bosmans, sp. n. (♂) from Tunisia, and L. saiss Bosmans, sp. n. (♂♀) from Morocco. Previously unknown sexes are first described for two species: L. leprieuri (Simon, 1875) from Algeria (♀) and L. parva (Denis, 1954) from Morocco (♂). One synonym is proposed: Lycosoides subfasciata (Simon, 1870) with L. flavomaculata (Lucas, 1843), syn. n. An identification key to all Lycosoides species of the Maghreb is provided. A complicated shape of the palpal conductor, with distinct dorsal and ventral branches, appears to be an important diagnostic character for the genus Lycosoides.

Organic Molecular Conductors Based on Tetramethyl-TTP: Structural and Electrical Properties Modulated by the Anion Size and Shape.

The tetramethyl derivative of bis-fused tetrathiafulvalene, 2,5-bis(4,5-dimethyl-1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene (TMTTP), has been successfully synthesized. Most of the radical cation salts consisting of TMTTP feature a high electrical conductivity of σrt = 101 to 102 S cm-1 on a single crystal. The anion shape and size of TMTTP conductors modulate the electrical properties. The PF6- and AsF6- salts exhibit metallic conductivity down to 10 K, while the ReO4- and AuI2- salts show metal-to-insulator (MI) transition at 126 and 11 K, respectively. Single-crystal X-ray structure analysis of (TMTTP)2X (X = PF6, AsF6, BF4, and ReO4) and (TMTTP)3AuI2 reveals that the donor packing motif is categorized as the so-called β-type. The tight-binding band calculations of (TMTTP)2X (X = ReO4, BF4, PF6, and AsF6) suggest these salts are characterized by quasi-one-dimensional Fermi surfaces. The band calculation based on X-ray structure analysis of (TMTTP)2ReO4 at 100 K demonstrates that the MI transition of this salt is associated with the charge ordering with the zigzag stripe pattern.

Reduction in the Electromagnetic Interference Generated by AC Overhead Power Lines on Buried Metallic Pipelines with Screening Conductors

This paper presents a numerical study on the reduction in the voltage and current induced on a 13.5 km buried metallic pipeline by an overhead power line. The mitigation effectiveness of different configurations and cross-section shapes of screening conductors is computed by means of a methodology that combines a 2D Finite Element Analysis with circuital analysis. A 35.72% reduction of the maximum induced voltage is obtained when 4 cylindrical steel screening conductors with 8 mm radius are buried 0.25m below the soil surface, along the pipeline path. The maximum induced pipeline current is reduced by 26.98%. A parametric study is also performed, to assess the influence of the per-unit-length admittance to earth of the screening conductors on the mitigation efficacy. The results show that screening conductors may help in reducing the inductive coupling between overhead power lines and buried metallic pipelines, and that the assumption of perfectly insulated screening conductors leads to an underestimation of the produced mitigation effect.

Compact Wideband Coplanar Stripline-to-Microstrip Line Transition Using a Bended Structure on a Two-Layered Substrate

A design of a compact coplanar strip (CPS)-to-microstrip line (MSL) transition using a bended structure on a two-layered substrate is presented. The proposed transition consists of a CPS taper and a bended CPS-to-MSL transition on a two-layered substrate. The CPS taper is formed on the lower substrate with low permittivity (εr = 3.38), and the bended CPS-to-MSL transition is formed on the upper substrate with high permittivity (εr= 10.2). The proposed transition is designed with analytical formulas obtained by applying EM-based conformal mapping without parametric tuning trials. The conductor shape of the bended CPS-to-MSL transition is adjusted to form an optimal Klopfenstein impedance taper. The proposed CPS-to-MSL transition optimally connects between a high impedance CPS line (~160 Ω) and a 50 Ω MSL, which typically results in a long transition length for ultra-wideband performance. The implemented transition bended in a sinusoid shape on the two-layered substrate provides good performance from 2 GHz to 17 GHz with the maximum 2 dB insertion loss per transition, and the horizontal length of the bended transition is reduced to 42.9% of the straight transition length. This bended transition is developed for use in mm-wave balanced antenna/detector feeds but can be applied to a variety of wideband balanced circuit modules, where compact circuit size is critical.

High Efficiency PMSM With High Slot Fill Factor Coil for Heavy-Duty EV Traction Considering AC Resistance

Electric vehicle (EV) systems require a high energy-efficiency traction motor so that the motors for EV traction should achieve high efficiency and power density. Hence, a permanent magnet synchronous motor (PMSM) for EV traction using a maximum slot occupation (MSO) coil has been investigated in this study. By applying the MSO coil, high torque density was achieved, but an additional loss, which decreases the efficiency, was incurred through alternating current (AC) resistance. To reduce the AC resistance of the MSO coil, the following process was performed: First, by investigation using the analytical method, pole/slot numbers, current density and number of parallel circuits affecting the frequency, the shape and number of conductors were chosen as important variables. Resistances of the MSO coil with a stator core were analyzed according to the chosen variables above. From the results, MSO coil applied PMSM with proper pole/slot numbers, current density, and parallel circuits was determined to improve the efficiencies at the base and maximum speeds. To accurately estimate the efficiency of the determined model, loss evaluation methods were explained. Subsequently, the determined MSO coil applied model was compared with the conventional model having round wires, and the improvements were verified by load testing.

Design of an ultra‐wideband coplanar strip‐to‐parallel stripline transition using an analytical model based on conformal mapping

AbstractA new design method of an ultra‐wideband coplanar strip (CPS)‐to‐parallel stripline (PSL) transition is presented. The proposed design is based on an analytical transition model obtained by conformal mapping. The proposed transition consists of a CPS‐to‐asymmetric PSL transition and an asymmetric PSL‐to‐PSL transition. The conductor shapes of the transition at top and bottom sides of the substrate are adjusted to obtain the optimal impedance matching and smooth field transformation. For measurements, the proposed transition is designed in a back‐to‐back configuration. To verify the proposed design, two transitions with different substrates are designed and fabricated. The PSL impedance is set at 50 Ω, but the CPS impedances are set at 147 and 120 Ω, respectively. The measured insertion loss of &lt;1 dB and return loss of &gt;10 dB have been obtained for more than 30 and 20 GHz bandwidths, respectively.