Double Dipole Research Articles

The high-Q THz stereo metasurface sensor based on double toroidal dipole with wide operating angle bandwidth

A highly sensitive terahertz stereo metasurface sensor, characterized by a high quality factor (Q-factor) and based on dual toroidal dipole (TD) resonance, has been proposed. The optimal structural parameters are ascertained by comparing the pertinent parameters of the stereo and planar structures in relation to TD modal excitation. The effective excitation of the TD mode is demonstrated using the calculations of multipole scattered power, reflection spectra, surface currents, electric fields, and magnetic field distributions. It is crucial that the stereo metasurface exhibits simplicity and that the dual TD resonance can be readily excited through simple adjustments in the distance and height of the intermediate gap. It also demonstrates exceptionally high sensitivity and Q-factor, both of which are essential for sensing applications. Moreover, the proposed stereo terahertz metasurface sensor still shows excellent sensing performance in a wide range of incidence angles (±40°), which is of great significance for practical applications. In conclusion, this structure offers a novel design framework for high-performance terahertz sensors based on the TD mode.

Research on the design of a novel composite solenoid model ship simulation magnetic source based on DTW

In order to study the simulation ability of a solenoid on a ship magnetic field, a new composite model based on a double row magnetic dipole array model with an ellipsoid was designed. The time-domain characteristics, such as magnetic field characteristics, magnetic inclination cosine, magnetic field scalar gradient, and magnetic field spatial distribution characteristics, were extracted. It was verified that the model can accurately simulate the magnetic field characteristics of ships through ship model experiments and simulation analysis. To further quantitatively and accurately analyze the simulation ability of the composite model for ship magnetic fields, a dynamic time wrapping measurement method based on one-dimensional time series was adopted to calculate the similarity of four characteristic quantities: magnetic field vector, magnetic field modulus, magnetic inclination cosine, and magnetic field scalar gradient. The results showed that the composite model has high simulation ability for ship magnetic fields.

A compact wideband hemispherical conformal antenna with pattern diversity

A novel wideband hemispherical conformal antenna with pattern diversity is proposed in this paper. This topology combines a radiator consisting of four double quasi-rhombic dipole antennas and a feeding network composed of four rat-race couplers. The pattern diversity is obtained when four different input ports in the feeding network are excited respectively. This design achieves an overlapping bandwidth of 24.9 % from 8.96 to 11.51 GHz on 4 ports, which is suitable for wideband applications in the X-band. The antenna radiator shares the aperture with the feeding network, resulting in a compact structure. A prototype antenna with a size of π × 0.632 × 0.66 (λ03) is fabricated, and the measured results generally correspond to the simulated results.

EARTHQUAKE FOCAL PARAMETERS in the CRIMEAN-BLACK SEA REGION in 2018–2019

The results of calculation and analysis of spectral and dynamic parameters of the sources (М0,r0, , , ησ, r, ū, Eu и Mw) of 24 Crimean earthquakes for 2018–2019 in the range of energy classes KП=5.8–11 are presented. 157 station amplitude spectra of P- and S- seismic waves recorded at seven regional digital seismic stations were used for calculations. The determination of dynamic parameters of the sources was carried out using the Brune theoretical dislocation model. The average values of the dynamic parameters of earthquake sources for 2018–2019 were in most cases estimated for several stations and for different types of waves, which ensured a small value of the degree of scattering of individual estimates. For the studied 2018–2019 earthquakes, the average values of the seismic moment М0, the radius of the circular dislocation r0, and the stress drop  were within the confidence intervals of the long-term dependencies М0(KП), r0 (KП) and (KП). For five strongest earthquakes of 2018 (January 31, April 24, September 9, September 13, and October 15 with KП=10.5–11) and two earthquakes of 2019 (May 8 and December 4), focal mechanism solutions were obtained within the framework of the double dipole model. Type of movement in the source of January 31, 2018 earthquake is a strike-slip with a normal fault component, of September 9 and September 13, 2018 – a normal fault, of April 24 and October 15, 2018, as well as May 8 and December 4, 2019 – a reverse fault. The spectral composition of seismic oscillations was additionally studied from the energy spectra of 15 earthquakes using records at the Alushta station located at distances 5–285 km from source zones. At the qualitative level, a shift of the spectrum maximum (fqmax) towards higher frequencies for weak shocks and close epicentral distances.

Broadband Microwave Microfluidic Spectroscopy to Capture Product Evolution in Electrosynthesis Reactions

Electrosynthesis plays an important role in chemical manufacturing with over 2 billion dollars in annual sales worldwide of products such as chlor-alkali and aluminum. Synthesis with an electrochemical driving force can afford unique chemical products that are difficult to achieve with conventional synthesis techniques. Electrosynthesis can also provide a more sustainable alternative to energy-intensive processes. For example, the most profitable electro-organic synthesis in industry is adiponitrile production, a precursor to Nylon 6,6, and the electrochemical route consumes less energy than conventional thermochemical methods. However, electrosynthesis reaction mechanisms are often complex and involve multiple biproducts that are difficult to distinguish, limiting product yield and cost efficiency. Prior work involves characterization with techniques such as NMR spectroscopy, mass spectrometry, and optical spectroscopy to understand product evolution during the reaction. These methods tend not to capture intermolecular interactions between substances, which is important for understanding the influence of the dielectric environment on reaction outcomes.Here, we propose to analyze the dielectric environment of electrosynthesis reaction mixtures with on-chip broadband microwave microfluidic spectroscopy (MMS) from 40 kHz – 110 GHz (see attached figure). MMS has been implemented previously for capturing broadband fluid effects such as electric double layer formation, ionic conduction, ion pairing, and dipole relaxations in a single measurement. We want to use MMS to diagnose the interactions between species during an electrolysis reaction and correlate these interactions with specific electrochemical mechanisms. We plan to test our idea by analyzing a model reaction, namely the Shono oxidation of N-Boc pyrrolidine, which is a well-studied electrosynthesis reaction. The goal is to validate our method with a known electrosynthesis reaction mechanism, then extend the technique to systems with an unknown mechanism.We performed broadband MMS of the reaction mixture at different time points to capture product evolution during the electrolysis. Then, we calibrated the resulting S-parameters and fit the data to equivalent circuit models. The equivalent circuit parameters were correlated to signatures from specific entities in the product mixture and used to develop a picture of the evolving dielectric environment. After validating our models with known literature about the Shono oxidation mechanism, we plan to extend our technique to other electrolysis reactions with unknown mechanisms. The goal is to provide a high-throughput technique for identifying key species and interactions that influence the outcome of electrolysis reactions. Figure 1

A Damped Double Dipole Antenna for UHF RFID Sensing in the Frequency Domain

Ultrahigh frequency (UHF) radio frequency identification (RFID) tags provide an inexpensive framework for distributed sensing, yet for the most cost-effective implementation, it is necessary to consider antenna design in concert with the capabilities of responsive materials that can be coupled to the tag response. Materials, such as functionalized carbon nanotubes (CNTs), have been engineered to change in resistance when exposed to a variety of analytes and have been incorporated in RFID tags to create low-cost sensors that work at a fixed reader–tag separation distance. This article presents a damped double dipole antenna design enabling UHF RFID tags that are able to sense changes in resistance of a sensing element (with a conductivity similar to that of printed CNT networks) regardless of reader–tag distance within the far-field read range. Simulations of the proposed design show two methods of operation, either by comparing the damping between two resonant peaks or by shifting the resonant frequency of the RFID tag. The first method is validated experimentally with surface mount resistors, showing a relative change in the effective antenna transmission coefficient, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\tau _{e}$ </tex-math></inline-formula> , of 0.2 for a 35% change in resistance of the sensing element.

An Adaptive Control Strategy for Underwater Wireless Charging System Output Power with an Arc-Shaped Magnetic Core Structure

Aiming at the problem of unstable output power of wireless charging systems for autonomous underwater vehicles (AUVs), a magnetic coupler (MC) with an arc-shaped core structure is introduced and an output power stabilization control strategy based on mutual inductance identification algorithm is proposed. Firstly, an arc-shaped MC with high tolerances, excellent magnetic coupling and weak electromagnetic interference (EMI) is designed for the cylinder-shaped AUV. Based on ANSYS Maxwell simulation, an analysis of the magnetic field and comparative misalignment tests are carried out for the arc-shaped and the double dipole core structures. Secondly, a mathematical model of the LCC-S type magnetically coupled resonant wireless power transfer (MCR-WPT) system is developed, and a particle swarm parameter identification algorithm with adaptive inertia weights is proposed. Finally, the output power is steadily controlled by real-time adaptation of the duty cycle for the Buck-Boost circuit. The results show there is a maximum error within 2.5% in mutual inductance identification when the load is changed from 0 Ω to 12 Ω and the mutual inductance is changed from 25 μH to 50 μH. The system output power is steady at around 680 W with a maximum fluctuation rate of 4.90%, which verifies the efficiency of the power stabilization control strategy.

A Compact Filter and Dipole Antenna With Its Phased Array Filtenna and ADMM-BO Learning for Use-Case Analog/Hybrid Beamforming in 5G mmWave Communications

In this article, a 5G compact millimeter-wave dipole antenna with high gain and its array filter-antenna is proposed, following a theoretical discussion is proposed. To increase the gain and focused mainbeam, the double dipole is inserted at the ground plane. The results show that the proposed antenna has an impedance band-width (IBW) of around 7.14% and 6.7 dBi gain at 28 GHz. Next, a 5G filter is proposed with 4% IBW and lower than 0.6 dB gain insertion loss. A simple phase-shifter with 2-bit structure is designed in an 8-elemens array filter-antenna with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.35\lambda $ </tex-math></inline-formula> spacing between the two elements which uses a meander-line to reduce mutual-coupling. First, the phased-array filtenna (filter-antenna) is fabricated to meet the analog beamforming challenge. The IBWs of the array filter antenna are approximately 3.5% with a high gain of 15 dBi. Second, a novel machine learning method is proposed as an alternating direction method of multipliers and Bayesian Optimization (ADMM-BO) is used in the hybrid beamforming for such partially-connected phased-array structures. Simulation and measurement results show that the proposed antenna and its array have a high gain in analog and hybrid beamforming and acceptable data rates. The data-rates of this array reach 100 Mb/s in SNRs higher than 10 dB. The amount for 0 dB SNR is 75 Mb/s. These results also indicate that the mainbeam shift is in the range of [−50°, 50°] with a gain in variations of around 1.5 dB and side lobe level (SLL) of about −10 dB at 50°.

Tectonic Earthquake Source Mechanism Model Based on Moment Theory

During the construction of strategic facilities, micro zoning is required to determine the peak values of terrain acceleration due to possible earthquakes. The acceleration of the soil in this case strongly depends not only on the power of the earthquake, but also on the earthquake source mechanism and the geodynamic state of the terrain. The known dislocation models of a single dipole with a moment and a pair of dipoles without a moment of the earthquake source mechanism satisfactorily describe the observed effects of the quadrant stress distribution on the Earth’s surface during earthquakes. When carrying out calculations within the framework of the theory of elasticity, the actions of the dipoles are expressed through volumetric forces. There are two known models of replacing the moments with equivalent forces: one of them is based on the equilibrium equations for an infinitely elastic space (Landau and Lifshitz,1965; Maruyama,1963), and the other is based on the representation theorem for elastic bodies, by introducing a singular internal volume, at the boundary of which there are dislocations (Vvedenskaya, 1969; Aki and Richards, 1983). Although these models involve moment effects, they themselves are derived from the momentless theory of elasticity. In our work, we propose a double dipole effect without a moment based on the moment theory of elasticity. The proposed model of the earthquake source mechanism is applied to solve the problem of stress variations in the Earth’s crust in Central Asia using the example of a particular earthquake with a simplified orientation of the rupture plane. Stress variation is understood as the difference in stresses in problems with and without an earthquake mechanism. Static stresses are obtained by solving the inverse elasticity problem with partially unknown boundary conditions. The lithosphere is a prismatic body consisting of several homogeneous blocks, the upper surfaces of which correspond to the relief of Central Asia. Verification of the results of the numerical solution is carried out by comparing the obtained stresses with previously established empirical values. As a priori stresses for solving the inverse problem, we used the solution of the elastic plane problem, the boundary conditions in which correspond to the lateral compression of the lithosphere of the region of the Indian and Arabian plates on the one hand, and the Eurasian plate on the other hand. The obtained solutions of the problem were used to analyze the geodynamic state of Central Asia. Based on the results of laboratory experiments, the unambiguity of the conclusions about the geodynamic state of the Earth’s crust (compression, extension) according to the Lode-Nadai coefficient, which are currently used by many researchers, is questioned. It is shown, contrary to earlier statements, that the values μσ = +1 and μσ = –1 can correspond simultaneously to both tension and compression cases, depending on the spatial form (ellipsoid) of the stress state. Geodynamic analysis of the Earth’s crust is carried out according to the Anderson method.

A double dipole kicker for off and on-axis injection into ALBA-II

Injection into the ALBA-II storage ring will be performed off-axis in a 4 meters straight section with a single multipole kicker. We present a novel topology for the coils of the injection kicker, named double dipole kicker (DDK). The resulting magnetic field is the superposition of two opposite dipoles, generated by four inner and four outer conductor rods. When the eight rods are powered, the dipole term cancels and the remaining multipole field is used for off-axis injection. Alternatively, when the four inner rods are switched off, an almost pure dipole is produced, that is useful for on-axis injection during the commissioning. A prototype of DDK is presently under design to be installed and tested in the existing ALBA storage ring. The positioning of the rods is calculated in order to maximize the kick efficiency in mrad/kA and minimise the disturbance to the orbit and the emittance of the stored beam. A metallic coating with optimised thickness along the inner ceramic vacuum chamber should provide compensation for the eddy currents induced field in order to minimize the disturbance to the stored beam while ensuring sufficiently low heat dissipation by the beam image currents.

Use of Thermochromic Properties of VO2 for Reconfigurable Frequency Selection

The thermochromic nature of vanadium dioxide (VO2) has facilitated many promising applications for reconfigurable frequency selectivity. The phase-changing property of VO2 was used to realise a reconfigurable frequency-selective surface (FSS) capable of manipulating electromagnetic waves for different functionalities. Diffractive optical elements (DOE) are used for diffracting laser beams to form conductive FSS images on the VO2 wafer for frequency selectivity. The dipoles on the VO2 wafer generate a stop band response of 12 dB and 10 dB for unit cells of the single dipole and double dipole at 3.5 GHz, respectively. A 10 GHz FSS array is projected by DOE on the 2-inch VO2 wafer with a filtering effect of 13 dB at 9.5–10.5 GHz. This solution is used to design a radar cross-section (RCS) modification FSS with reflected waves of about 20 dB higher reflectivity in the backscattering direction than in the specular direction.

Significance of non-Fourier heat flux on ferromagnetic Powell-Eyring fluid subject to cubic autocatalysis kind of chemical reaction

The transport of heat and mass has numerous uses in scientific engineering progression. The established laws of heat and mass transport i.e., Fourier and Fick laws do not foresee thermo-solute phenomena of relaxation time. The aim of current study is to analyze the concept of ferromagnetic flow of Eyring-Powell liquid with double magnetic dipole and homogeneous/heterogamous reactions over a flat plate. An external magnetic field by reason of two equivalent line dipole which are equidistant from the wall and normal to the flow plane has been applied. The heat flux model of Cattaneo-Christov is employed to modified method of Fourier's law to show the transport of heat structures. Convergent solutions to the non-linear formulation are derivative and scrutinized using homotopic technique. Characteristic of various parameter like magneto-thermomechanical [ferro-hydrodynamic] interface parameter, homogeneous/heterogeneous reaction, dimensionless temperature relaxation for thermal profile are displayed through graphs. This study reports that the fluid factor and ferro-hydrodynamic interaction factor show conflicting behaviour on velocity field. Further analysis shows that the Prandtl number decline the temperature field.

Quench Behavior of Prototype Nb-Ti HL-LHC Dipole Canted Cos-Theta Orbit Corrector Magnets

The HL-LHC project is an upgrade of the LHC that requires double aperture dipole correctors. In 2015, CERN selected Canted Cos-Theta (CCT) magnet, and the development of the MCBRD magnets followed. Since then, a prototype (P1) has been built and measured at CERN, and quench results agree with simulations. In 2017, China joined the programme with in-kind prototypes and twelve (four spares) series magnets with WST, IMP, IHEP, and BAMA efforts. The first MCBRD magnet built in China is the second prototype (P2) of the programme. This magnet was subjected to triggered energy extractions at CERN magnet test facility. The energy extraction is used for magnet protection, keeping voltage-to-ground and hot-spot temperature below 560 V and 250 K, respectively. A high magnetic-field change rate during the magnet discharge from high currents causes a substantial quench-back due to the heat generated by the eddy currents in the magnet formers. A specialized software, ProteCCT, was developed as part of the STEAM project to simulate such a unique quench behaviour. This contribution focuses on comparing measured results between the P1 and P2 magnets, and P2 quench measurement and simulation results. The correction factors available in the ProteCCT software allow matching the measured results. We identify measurements needed to refine simulation inputs further and improve the simulation predictive capability.

Active continuous control of terahertz wave based on a reflectarray element-liquid crystal-grating electrode hybrid structure.

In this work, a new and efficient terahertz reflective phase shifter is proposed. The phase shifter is composed of a metal-dielectric-metal structure with a double dipole patch array, as well as copper grating electrodes immersed within the nematic liquid crystal. More specifically, the employed copper grating electrodes consist of two sets of cross-distributed comb grids, whereas at each set of comb grids can be applied an external bias voltage separately. On top of that, the electric field in the liquid crystal (LC) layer can be continuously changed by enforcing an innovative technique. Consequently, the orientation of the LC molecules was fully controlled by the applied electric field, since the dielectric constant of the LC is controlled by the biased voltage. The phase of the reflective electromagnetic wave can be continuously manipulated. Under this direction, the experimental results show that the phase shift exceeds the value of 180° in the range of 102.5 GHz-104.3 GHz, where the maximum phase shift is 249° at 103 GHz. The proposed work provides a new regulation concept for the implementation of LC-based terahertz devices and the respective applications in the terahertz reconfigurable antennas field.

A Wideband Endfire Double Dipole Antenna Fed From Double-Ridge Gap Waveguides for Multibeam Array Application

In this letter, an endfire double dipole antenna fed from double-ridge gap waveguides (DRGWG) is proposed and designed for multibeam array application. Two dipoles with different lengths are connected to the extension of the ridges of DRGWG in series. Different resonances can be generated by these two dipoles, which contributes to a wide impedance bandwidth, high gain, and stable radiation patterns across the working band. The double dipole antenna is vertically polarized and has a wide H-plane beamwidth suitable for beam scanning application. To verify the performance of the double dipole antenna, a Butler matrix is designed based on ridge gap waveguides to feed a 1 &#x00D7; 4 double dipole array arranging in H-plane. The maximum gains achieved for Ports 1 and 2 are 13.94 and 12.68 dBi, respectively. Besides, the simulated radiation efficiencies for Ports 1 and 2 are both above 83&#x0025;.

Impact of Ferromagnetic Nanoparticles Submerged in Chemically Reactive Viscoelastic Fluid Transport Influenced by Double Magnetic Dipole

The present article summarized the effects of double magnetic dipole for chemically reactive viscoelastic fluid in the presence of two different ferromagnetic particles, namely, nickel zinc ferrite (NiZnFe2O4) and magnetite ferrite (Fe3O4). Due to double magnetic dipole, an external magnetic field is applied normal to the flow. Blood is used as base fluid due to its viscoelastic fluid properties. The Cattaneo‐Christov heat flux model is used for heat transport phenomena. The physical model is formulated in the form of partial differential equations which are then converted into ordinary differential equations using the suitable transformations. The system is solved numerically using shooting method along with Runge‐Kutta‐Fehlberg method. The characteristics of different parameters like the strength of homogeneous‐heterogeneous reactions (k1 and k2), ferrohydrodynamic interaction (β1), Schmidt number (Sc), Deborah number (α1a), and thermal relaxation time (α1c) on velocity, temperature, and concentration profiles are analyzed through graphs and in tabular form. It has been observed that as magnetic dipole creates a force which attracts the ferrite particles, hence, it slows down the velocity profile. Concentration field depresses due to the presence of strength of heterogeneous reaction parameter k2.It is also noted that by expanding values of thermal relaxation time (α1c), the temperature profile shows a reverse behavior.

Radio‐magnetotelluric and controlled‐source magnetotelluric surveys on a frozen lake: Opportunities for urban applications in Nordic countries

ABSTRACTIn a novel approach, we have carried out controlled‐source and radio‐magnetotelluric measurements in the frequency range of 2–250 kHz on a frozen lake located over a planned major multi‐lane underground road tunnel near the city of Stockholm. The aim was to gain a better understanding of the resistivity variations above and, potentially, within the crystalline bedrock. Previous studies on the lake water using the boat‐towed radio‐magnetotelluric technique at the higher end of the frequency band lacked resolution at depth and could not provide conclusive information about bedrock level and potential fracture systems within the bedrock. Taking advantage of Nordic winters, we measured four profiles on the frozen lake complementing the previously acquired boat‐towed radio‐magnetotelluric data utilizing a double horizontal magnetic dipole transmitter that generated signals down to 1 kHz. The new resistivity models, incorporating the lower frequency data, show improvements and deeper penetrations based on a combined analysis of penetration depth, data misfits and sensitivity studies. The resistivity models also show better correlation with the available high‐resolution shallow water seismic reflection data and the geological observations. A potential fracture system within the bedrock can also be inferred better in the new models. The idea of running similar surveys on frozen lakes can be further exploited in similar conditions in countries such as Sweden, where approximately 7% of the land is covered by freshwater bodies and poorly explored for infrastructure planning projects.

Double Meander Dipole Antenna Array with Enhanced Bandwidth and Gain

In this paper, a new design of high gain and wide bandwidth microstrip patch antenna array containing double meander dipole structure is proposed. Two in-phase resonant frequencies in the Ku-band (12–18 GHz) could be achieved in the double meander dipole array structure, which lead to enhance impedance bandwidth without costing extra design section. Besides, further enhanced gain of 2 dBi of the array over the entire operating frequency range has been achieved by introducing a double-layer substrate technique. The proposed antenna has been fabricated using the E33 model LPKF prototyping PCB machine. The measurement results have been performed, and they are in very good agreement with the simulation results. The measured –10 dB impedance bandwidth indicates that the array provides a very wide bandwidth which is around 30% at the center frequency of 15.5 GHz. A stable gain with a peak value of 10 dBi is achieved over the operating frequency range. The E- and H-plane radiation patterns are simulated, and a very low sidelobe level is predicted. The proposed antenna is simple and has relatively low-profile, and it could be a good candidate for millimeter wave communications.

Double electric dipole moment contribution model of the Verdet constant of paramagnetic magneto-optical materials

Besides considering the influence of the transition dipole moment, the impact of the external magnetic field and photoelectric field on the electron’s movement is also taken into account by using forced vibration to correct the electric dipole moment, and a unique double electric dipole moment contribution model of the Verdet constant of paramagnetic magneto-optic materials is deduced. Using terbium gallium garnet (TGG) crystal as an example, various microscopic effects and energy levels splitting inside the paramagnetic magneto-optic materials are analyzed in detail. Then, the Verdet constant of TGG crystal under different theoretical models is quantitatively solved. Compared with current theories, the results calculated using the double electric dipole moment contribution model are more consistent with the experimental data, indicating that the model has certain advantages.

Understanding Interface Dipoles at an Electron Transport Material/Electrode Modifier for Organic Electronics.

Interface dipoles formed at an electrolyte/electrode interface have been widely studied and interpreted using the “double dipole step” model, where the dipole vector is determined by the size and/or range of motion of the charged ions. Some electron transport materials (ETMs) with lone pairs of electrons on heteroatoms exhibit a similar interfacial behavior. However, the origin of the dipoles in such materials has not yet been explored in great depth. Herein, we systematically investigate the influence of the lone pair of electrons on the interface dipole through three pyridine derivatives B2–B4PyMPM. Experiments show that different positions of nitrogen atoms in the three materials give rise to different hydrogen bonds and molecular orientations, thereby affecting the areal density and direction of the lone pair of electrons. The interface dipoles of the three materials predicted by the “double dipole step” model are in good agreement with the ultraviolet photoelectron spectroscopy results both in spin-coated and vacuum-deposited films. These findings help to better understand the ETMs/electrode interfacial behaviors and provide new guidelines for the molecular design of the interlayer.