Order Resonance Research Articles

Time-step dependent force interpolation scheme for suppressing numerical Cherenkov instability in relativistic particle-in-cell simulations

The WT scheme, a piecewise polynomial force interpolation scheme with time-step dependency, is proposed in this paper for relativistic particle-in-cell (PIC) simulations. The WT scheme removes the lowest order numerical Cherenkov instability (NCI) growth rate for arbitrary time steps allowed by the Courant condition. While NCI from higher order resonances is still present, the numerical tests show that for smaller time steps, the numerical instability grows much slower than using the optimal time step found in previous studies. The WT scheme is efficient for improving the quality and flexibility of relativistic PIC simulations.

A compact dual‐band zeroth‐order resonator antenna loaded with meander line inductor

A novel zeroth-order resonator (ZOR) meta-material (MTM) antenna with dual-band is suggested using compound right/left handed transmission line as MTM. In this article, suggested antenna consists of patch through series gap, two meander line inductors, and two circular stubs. The MTM antenna is compact in size which shows dual-band properties with first band centered at 2.47 GHz (2.05-2.89 GHz) and second band is centered at 5.9 GHz (3.70-8.10 GHz) with impedance bandwidth of (S11 < − 10 dB) 34.69% and 72.45%, respectively. At ZOR mode (2.35 GHz), the suggested antenna has overall dimension of 0.197λo × 0.07λo × 0.011λo with gain of 1.65 dB for ZOR band and 3.35 dB for first positive order resonator band which covers the applications like Bluetooth (2.4 GHZ), TV/Radio/Data (3.700-6.425 GHz), WLAN (5-5.16 GHz), C band frequencies (5.15-5.35, 5.47-5.725, or 5.725-5.875 GHz) and satellite communication (7.25-7.9 GHz). The radiation patterns of suggested structure are steady during the operating band for which sample antenna has been fabricated and confirmed experimentally. It exhibits novel omnidirectional radiation characteristics in phi = 0° plane with lower cross-polarization values.

Constrained layer damping treatment of a model support sting

In transonic wind tunnel tests, the pulsating airflow is prone to induce the first order resonance of the sting support system. The resonance limits the wind tunnel test envelope, makes the test data inaccurate, and brings potential security risks. In this paper, a model support sting with constrained layer damping (CLD) treatment is proposed to reduce the first order resonance response. The CLD treatment mainly consists of material selection and geometric optimization processes. The damping performance of the optimized CLD sting is compared with an AISI 1045 steel sting with the identical diameter in laboratory. The frequency response curves of the CLD sting support system and the AISI 1045 steel sting support system are obtained by sine sweep tests. The test results show that the first order resonance response of the CLD sting support system is 37.3% of that of the AISI 1045 steel sting support system. The first order damping ratios are calculated from the frequency response curves by half power point method. It is found that the first order damping ratio of the CLD sting support system is approximately 2.6 times that of the AISI 1045 steel sting support system.

Studying localized surface plasmon resonances in the THz region for subwavelength spiral disks

Spoof localized surface plasmon resonances (LSPRs) in the THz range are promising for bio-sensing and spectroscopy. Using long spiral grooves allows improving the surface mode confinement of LSPRs in the long-wavelength region. Our numerical simulations of sub-wavelength spiral gold disks in the range of 0.04–6 THz have shown that in case of Drude conductivity and normal incidence of EM radiation only the first- and second-order dipole localized surface plasmon resonances (LSPRs) are excited. High order resonances arise at inclined incidence. The spectra and 2D distributions of the EM field at the resonant frequencies depend on the number of spiral arms and symmetry of the spiral structure.

A 3-D Printed Bandpass Filter Using TM₂₁₁-Mode Slotted Spherical Resonators With Enhanced Spurious Suppression

This article presents a Ka -band fourth-order slotted spherical resonator waveguide bandpass filter (BPF) with a wide spurious suppression stopband. It uses the first higher-order TM211 mode rather than the fundamental TM101 mode of the spherical resonator in order to obtain a higher unload quality factor ( $Q_{\mathrm {u}}$ ) for smaller in-band insertion loss, as well as a larger filter volume that gives better tolerance to fabrication errors in high frequency applications. By introducing slots that interrupt surface currents, the fundamental TM101 and two higher spurious modes (TE101 and TM311) can be suppressed without compromising the unloaded quality factor of the TM211 mode. In addition, the filter topology is optimized to further enhance the suppression level of the spurious passbands. A Z-shaped topology has been found effective in decreasing the coupling strength of the spurious TM311 mode. An analysis is performed to demonstrate the better tolerance of the Z-shaped filter over the conventional TM101-mode spherical resonator filter. For verification, a fourth-order slotted spherical resonator waveguide BPF with a center frequency of 31 GHz and bandwidth of 880 MHz is designed and manufactured using a selective laser melting (SLM) 3-D printing process. The measured results show an average in-band insertion loss of 1.53 dB, and a passband return loss better than 13.6 dB. The stopband of the filter is extended up to 40.9 GHz with a rejection level greater than 20 dB.

High-Performance Nano-Sensing and Slow-Light Applications Based on Tunable Multiple Fano Resonances and EIT-Like Effects in Coupled Plasmonic Resonator System

A basic plasmonic system, consisting of a stub metal-insulator-metal (MIM) waveguide coupled with a ring resonator, is presented to realize Fano resonance and electromagnetically induced transparency-like (EIT-like) effect, which are numerically calculated by the finite element method (FEM). Meanwhile, the formation mechanism of Fano resonance is analyzed according to numerical simulations. Besides, the coupled mode theory (CMT) and the standing wave theory are used for explaining the Fano and EIT-like resonances phenomenon. Based on this system, an inner ring cavity is connected to the ring resonator by a slot and another ring cavity is later introduced under the stub resonator in order to constitute a new coupled plasmonic resonator system, providing quadruple Fano resonances and double EIT-like responses finally. In addition, the Fano and EIT-like resonances can be independently tuned by adjusting the structural parameters, which makes the design of highly integrated photonic circuits more flexible. The main contribution of this paper is that the proposed structure has a relatively good sensitivity of 1600 nm/RIU and an ultra-high FOM value of $1.2\times 10^{6}$ as a refractive index nanosensor. Moreover, it can serve as an all-optical switch with a high on/off extinction ratio of about 43 dB. Additionally, its maximum group delay time and group index are about 1.49 ps and 221, indicating that the proposed system has a pretty good slow light effect. Therefore, the proposed structures are believed to have significant applications in high-performance nanosensors, switches, slow light devices and nonlinear areas in highly integrated plasmonic devices.

Voltage-Tunable Superconducting Resonators: A Platform for Random Access Quantum Memory

In quantum computing architectures, one important factor is the trade-off between the need to couple qubits to each other and to an external drive and the need to isolate them well enough in order to protect the information for an extended period of time. In the case of superconducting circuits, one approach is to utilize fixed frequency qubits coupled to coplanar waveguide resonators such that the system can be kept in a configuration that is relatively insensitive to noise. Here, we propose a scalable voltage-tunable quantum memory (QuMem) design concept compatible with superconducting qubit platforms. Our design builds on the recent progress in fabrication of Josephson field effect transistors (JJ-FETs) which use InAs quantum wells. The JJ-FET is incorporated into a tunable coupler between a transmission line and a high-quality resonator in order to control the overall inductance of the coupler. A full isolation of the high-quality resonator can be achieved by turning off the JJ-FET. This could allow for long coherence times and protection of the quantum information inside the storage cavity. The proposed design would facilitate the implementation of random access memory for storage of quantum information in between computational gate operations.

Measurement of RF characteristics for Superconducting Quarter-wave Resonator

RF characteristics of unloaded quality factor (Q0) and accelerating electric field (Eacc) were measured for superconducting quarter-wave resonator (QWR) in order to verify the performance. For the accurate measurement of RF characteristics, the measurement method of Q0 based RF power and RF coupling coefficient was used, and the measurement uncertainty was calculated with statistics analysis of systematic error in RF measurement system. The superconducting QWR was designed with a resonant frequency of 101.28 MHz and an accelerating electric field (Eacc) of 6 MV/m at a cavity dissipation power of 10 W in the high-intensity and energy isotope separator online device (HIE-ISOLDE) project at CERN. Q-slopes and RF coupling coefficients were measured for three QWRs at the resonant frequency 101.28 MHz. Q0 values of QWRs were measured 4.55 × 108, 3.78 × 108 and 3.17 × 108 at the 6 MV/m, respectively, and the measurement uncertainty of Q0 and Eacc were calculated 2.92% and 3.32%. Performances of superconducting QWRs were acceptable to operate the beam acceleration with consideration of cryomodule capacity in HIEISOLDE project.

Structure design and analysis of tracking frame for horizontal telescope

针对某700 mm口径地平式望远镜系统，提出了一种U型跟踪架的结构设计方案。跟踪架结构中方位轴系采用双排密珠球轴承，轴承设计为双排轴向止推钢珠及双排径向钢珠结构，滚珠的密集及均化作用可保证轴系具有高回转精度。俯仰轴系设计采用一端固定、一端游动的结构方式，以补偿机械误差及热变形对回转精度的影响。对望远镜跟踪架进行有限元建模，分析得出其一阶谐振频率可达到47.6 Hz，说明它具有良好的模态特性。使用电子水平仪及自准直仪分别对方位轴及俯仰轴进行定量检测，方位轴轴系晃动优于1.3″，俯仰轴轴系晃动优于1.8″。通过仿真分析及实验测试，证明设计的望远镜跟踪架结构具有高刚度及高回转精度，为同类跟踪架的结构设计提供了一定的参考价值。

Finite element simulations of second order wave resonance by motions of two bodies in a steady current

Wave resonance by forced motions of two bodies in a steady current is investigated in this paper. The work is based on second order theory of potential flow and the simulation is through a higher order finite element method with 12-node elements in time domain. Boundary conditions are imposed on mean positions of all boundaries. The i-th (i = 1,2) order potentials in the fluid domain at each time step are obtained by solving the finite element system and the spatial derivatives of the potential are calculated by differencing the shape functions directly. Numerical cases are given for two rectangular cylinders undergoing in specified oscillations in a steady current. The first and second order resonances have been captured at their resonant frequencies at different current speeds, which does not seem to have been studied yet. The numerical result shows that the current speed has important influence on the wave and force at both first and second order resonances.

Strongly confined localized surface plasmon resonance (LSPR) bands of Pt, AgPt, AgAuPt nanoparticles

Multi-metallic alloy nanoparticles (NPs) can enable the advanced applications in the energy, biology, electronics, optics and catalysis due to their multi-functionality, wide tunable range and electronic heterogeneity. In this work, various mono-, bi- and tri-metallic nanostructures composed of Ag, Au and Pt are demonstrated on transparent c-plane sapphire (0001) substrates and the corresponding morphological and optical characteristics are thoroughly investigated. The resulting Pt and AuPt NPs in this study demonstrate much enhanced LSPR responses as compared to the pure Pt NPs from the previous studies, which was contributed by the synergistic effect of Au and Pt and improved surface morphology. These results are sharply distinct in terms of surface morphology and elemental variability from those obtained by the dewetting of monometallic Ag, Au and Pt films under the similar growth conditions, which is due to the distinct dewetting kinetics of the bi-layer and tri-layer films. These NPs exhibit strongly enhanced localized surface plasmon resonance (LSPR) bands in the UV-VIS wavelengths such as dipolar, quadrupolar, multipolar and higher order resonance modes depending upon the size and elemental composition of NPs. The LSPR bands are much stronger with the high Ag content and gradually attenuated with the Ag sublimation. Furthermore, the VIS region LSPR bands are readily blue shifted along with the reduction of NP size. The Ag/Pt bi-layers and Ag/Au/Pt tri-layers are systematically dewetted and transformed into various AgPt and AgAuPt nanostructures such as networked, elongated and semispherical configurations by means of enhanced surface diffusion, intermixing and energy minimization along with the temperature control. The sublimation of Ag atoms plays a significant role in the structural and elemental composition of NPs such that more isolated and semispherical Pt and AuPt NPs are evolved from the AgPt and AgAuPt NPs respectively.

Vibration Analysis of a Rotating Flywheel/Flexible Coupling System with Angular Misalignment and Rubbing Using Smoothed Pseudo Wigner–Ville Distributions

Detection of early faults such as misalignment, rotor rubbing, shaft crack and bearing fault is necessary to avoid harmful and even catastrophic influences on rotating machinery. In this paper, the accelerating horizontal and pitching vibration responses of flywheel/flexible coupling model of an actual diesel generator, with angular misalignment and rubbing faults, are investigated using the smoothed pseudo-Wigner–Ville distributions (SPWVDs). Numerical simulations are performed through the dynamical equations of the flywheel/flexible coupling system; the results suggest that when an angular misalignment fault occurs, the super-harmonic resonance of order 3 can be found in the horizontal and pitching vibration signals. Meanwhile, both the 3fr and 5fr components (i.e., 3 and 5 times of the rotating frequencies) can also be found in SPWV distribution spectra. When rubbing fault occurs, more abundant sub- and super-harmonic frequency components can be observed in SPWV distribution spectra. Overall, the investigation shows that the smoothed pseudo-Wigner–Ville distribution spectra reveal obvious differences between the acceleration responses of the rotating system with different faults.

Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes

In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.

Frequency tunable printed antenna with 90% size reduction for wireless communication applications

A compact single layer coaxial probe-fed microstrip antenna with frequency tuning capability is proposed in this paper. The proposed antenna occupies a compact size of only 35 × 35 × 1.6 mm3. The proposed antenna consists of a rectangular defected microstrip structure (DMS) embedded at the rectangular patch and narrow rectangular slot loaded modified ground plane structure (MGS) to create a lower order resonance at 1.85 GHz, which corresponds to 90% miniaturization of the proposed antenna. The lower resonant frequency of the proposed antenna can be adjusted from 4.35 GHz down to 1.85 GHz with 3.59% fractional bandwidth by increasing the length of the slot embedded in the ground plane. The design structure yields an independent control of the desired resonant frequency, gain, fractional bandwidth and compactness of the antenna. By changing the dimension of the ground plane slot, the same antenna geometry supports any wireless communication applications in the frequency range of 1.85 to 4.35 GHz such as 1.92 GHz PCS, 1.9 GHz PHS, 2.4 GHz Bluetooth, 2.6 GHz extended UMTS, 2.8 GHz IMT, 2.4/3.6 GHz WLAN and 2.5/3.5 GHz Wi–MAX etc.

Systematic investigation on quad-metallic AgAuPdPt and tri-metallic AuPdPt NPs through the solid-state dewetting of quad-layer Ag/Au/Pd/Pt thin films on c-plane sapphire.

Multi-metallic alloy nanoparticles (MNPs) can offer valuable opportunities to meet the various demands of applications. MNPs consist of various noble metallic elements can combine diverse electronic, optical and catalytic properties in a single NP configuration, thus taking the advantage of each element. In this paper, the fabrication of tri- and quad- metallic alloy NPs with noble elements (Ag, Au, Pd and Pt) and the corresponding localized surface plasmon resonance (LPSR) properties are systematically demonstrated. Tri- and quad-metallic alloy NPs come in various size and configurations by the solid-state dewetting of Ag/Au/Pd/Pt quad-layers on sapphire (0001). Tri-metallic AuPdPt NPs are demonstrated by the systematic control of growth temperature along with the significant Ag atom sublimation. Strongly enhanced and tunable LPSR is exerted in the UV-VIS regions depending upon the size, configuration, spacing and elemental composition of the MNPs. The size dependent LSPR response of MNPs is discussed based on the absorption and scattering along with the excitation of dipolar, quadrupolar, high order and multipolar resonance modes. The MNPs exhibit much stronger and dynamic LSPR bands as compared with the monometallic Pt and Pd NPs with the comparable size and configurations.

New results on orbital resonances.

Perturbative analyses of planetary resonances commonly predict singularities and/or divergences of resonance widths at very low and very high eccentricities. We have recently reexamined the nature of these divergences using non-perturbative numerical analyses, making use of Poincaré sections but from a different perspective relative to previous implementations of this method. This perspective reveals fine structure of resonances which otherwise remains hidden in conventional approaches, including analytical, semi-analytical and numerical-averaging approaches based on the critical resonant angle. At low eccentricity, first order resonances do not have diverging widths but have two asymmetric branches leading away from the nominal resonance location. A sequence of structures called "low-eccentricity resonant bridges" connecting neighboring resonances is revealed. At planet-grazing eccentricity, the true resonance width is non-divergent. At higher eccentricities, the new results reveal hitherto unknown resonant structures and show that these parameter regions have a loss of some - though not necessarily entire - resonance libration zones to chaos. The chaos at high eccentricities was previously attributed to the overlap of neighboring resonances. The new results reveal the additional role of bifurcations and co-existence of phase-shifted resonance zones at higher eccentricities. By employing a geometric point of view, we relate the high eccentricity phase space structures and their transitions to the shapes of resonant orbits in the rotating frame. We outline some directions for future research to advance understanding of the dynamics of mean motion resonances.

Class-F GaN HEMT Amplifiers Using Compact CRLH Harmonic Tuning Stubs Designed Based on Negative Order Resonance Modes

Class-F GaN HEMT Amplifiers Using Compact CRLH Harmonic Tuning Stubs Designed Based on Negative Order Resonance Modes

Miniaturized RFID Reader Antennas Based on CRLH Negative Order Resonance

This article presents a type of miniaturized high-efficiency patch antennas for UHF radio frequency identification (RFID) reader applications based on the composite right-/left-handed (CRLH) negative order resonance. Miniaturization is achieved by using the first negative order resonance (−1st mode). These proposed CRLH resonators are realized by etching gap on the patch surface, which acts as a series left-handed (LH) capacitor as well as an effective radiator, and using metallic screws on the corner as steadying posts while also providing an LH inductor. Different from the traditional mushroom structures, these screws are placed on the two sides or corner of the unit cells allowing unobstructed current and field flowing inside the cavity. This enhances the quality factor and radiation efficiency. In addition, only metallic sheets, screws, and one thin substrate are used in the design, therefore dielectric loss is basically eliminated. Overall, these proposed antennas achieve a miniaturized size, as well as a high gain and radiation efficiency. The radiation characteristics of these RFID antennas are similar to the conventional patch antennas due to the −1st-order operation. Four antennas, including linearly polarized, circularly polarized (CP), frequency-tunable, and polarization/frequency-reconfigurable antennas, are carefully designed, investigated, and experimentally verified. Remarkable agreement has been observed between simulation and measurement. These antennas well cover 902–928 MHz UHF band. RF range tests are carried out for application verification. They demonstrate a compact size, low-cost, low-loss, and high efficiency with easy implementation. The CP antennas exhibit a good bandwidth and an excellent axial ratio in the whole upper semisphere. They have been selected for mass production, which illustrates a good engineering application example of CRLH metamaterial antennas.

Digital electro-optic exclusive OR and NOR gates utilizing a single micro-ring resonator

In this paper, we present the concept design and implementation of a single silicon-based micro-ring resonator in order for it to operate as exclusive OR and NOR mode. The micro-ring resonator utilizes carrier-injection based electro-optic modulation scheme, with modulation voltage ranging from 0 V up to 1.4 V. A single micro-ring resonator is used to simultaneously generate both XOR and XNOR digital output mode operation at the drop as well as through port respectively. The modulation voltage required for the proposed design together with its operation wavelength is found by resonance spectra analysis on the ring. Time domain simulations where two electrical information bit streams of 10 Gbps data rate injected into the circuit design have been carried out to display its working operation.

Features of the Dynamics of Objects Moving in the Neighborhood of the 1 : 3 Resonance with the Earth’s Rotation

The paper presents the results of the study of the dynamic structure of near-Earth orbital space in the region of the 1 : 3 resonance with the Earth’s rotation. The results of an extensive numerical-analytical experiment to study the orbital evolution of objects moving in the range of semimajor axes from 20 250 to 20 280 km, with inclinations from 0 to 90 degrees, are presented. The zones of action of five components of orbital resonance and apsidal-nodal secular resonances of low orders are revealed. Maps of the distribution of identified resonances are given. The analysis of the dynamic structure of the orbital space using the fast Lyapunov characteristic (MEGNO) is presented, and the MEGNO map of the region in the plane section (orbit inclination, semimajor axis) is given. It has been shown that the dynamic evolution of most of the orbits is chaotic, which is due to the superposition of different types of resonances.