Order Resonance Research Articles

Force Feedback Control Method of Active Tuned Mass Damper

Active tuned mass dampers as vibration-control devices are widely used in many fields for their good stability and effectiveness. To improve the performance of such dampers, a control method based on force feedback is proposed. The method offers several advantages such as high-precision control and low-performance requirements for the actuator, as well as not needing additional compensators. The force feedback control strategy was designed based on direct-velocity feedback. The effectiveness of the method was verified in a single-degree-of-freedom system, and factors such as damping effect, required active force, actuator stroke, and power consumption of the damper were analyzed. Finally, a simulation study was performed by configuring a main complex elastic-vibration-damping system. The results show that the method provides effective control over modal resonances of multiple orders of the system and improves its dynamics performance.

Compact Multiband Interdigital-Coupled-Fed Planar Antenna with Stepped-Impedance Structures for Mobile Handsets

A new compact multiband planar antenna combining an interdigital-coupled feeding line and one stepped-impedance structure is presented here. This antenna is capable of generating five resonant modes to cover the ISM 915/2400/5800 MHz bands, GPS band, and IMT C-band, respectively. The five resonant frequencies covered by the proposed antenna can be adjusted individually by controlling the impedances and electrical lengths of the corresponding stepped-impedance sections. An additional advantage of the proposed stepped-impedance structure is its ability to suppress higher order resonance modes, thus filtering out unwanted interference. The proposed antenna utilizes a simple planar compact structure and occupies a small area of only 12 × 30 mm2. Details of the antenna design and experimental results are presented and discussed.

Design of Dual-Band Bandpass Filter With High Isolation and Wide Stopband

A simple and effective method to design a dual-band bandpass filter with high isolation and wide stopband is presented and validated using symmetric open-circuited stub-loaded resonators. By adjusting the electric length and the ratio of characteristic admittance of the resonators, the first two resonant frequencies are identical, but the higher order resonant frequencies dispersed in the upper stopband to extent the bandwidth of stopband. Two transmission zeros are introduced to obtain high isolation and selectivity between the two passbands by placing them in the appropriate position. Proper feeding position is selected to further improve the attenuation of stopband. The measured results highly agree with the simulated one. Measured results demonstrate the isolation level of 40 dB, attenuation of larger than 28 dB, and a wide stopband.

ワイヤレス電力伝送における高次共振を用いたマルチバンドコイルの設計

ワイヤレス電力伝送における高次共振を用いたマルチバンドコイルの設計

The use of stability bands to improve the performance of quadrupole mass filters

The possibility of increasing the resolving power of quadrupole mass filters has been discussed. It has been shown that the limitations associated with the finite time of flight imposed by Von Zahn’s rule are modified while using the islands of stability that appear when quadrupole is excited by the additional signals. By calculation of the exponential increment of growth of the oscillation amplitude the effect of the acceleration of mass separation and improvement of the peak shape, when the islands of stability are used for ion filtering, is explained. The case of the excitation by two signals at different frequencies has been studied theoretically. The conditions under which suppression of the first order resonance for one of the directions of motion is obtained. The direct modeling of the peak shape of the mass filter shows the possibility of obtaining a resolution of 10,000 with a time of flight of ions through the quadrupole of 100 cycles of the main RF supply, and low sensitivity of the new operating mode to the nonlinear field distortions in the quadrupoles with rods of circular cross sections.

Tm-fiber pumped single-longitudinal-mode Ho:LuVO4 laser

We demonstrated a Tm-fiber pumped single-longitudinal-mode Ho:LuVO4 laser with intra-cavity Fabry–Perot etalons. By the use of an output coupler with a transmission of 2%, the Ho:LuVO4 laser generated a continuous-wave output power of 609 mW at 2074.72 nm. By inserting the 1- and 6-mm etalons into the resonator in order, we obtained a single-longitudinal-mode laser with a wavelength of 2074.91 nm, the maximum output power of which is 163 mW with the pump power of 14 W, corresponding to a slope efficiency of 2.3%. To the best of our knowledge, the intra-cavity etalons Ho:LuVO4 laser operating at single-longitudinal-mode is reported for the first time.

The Transmission Characteristics of Asymmetrical Multi-Teeth-Shaped Plasmonic Waveguide Structure

The transmission characteristics of asymmetrical multi-teeth-shaped plasmonic waveguide structure are investigated theoretically and numerically. The tunable dual flat bandgaps are achieved in our proposed structure. This feature can provide a promising application for plasmonic bandstop filter. In addition, according to the hybrid effects of the first order resonance and high order resonance of N identical asymmetrical teeth, a sharp transmission peak can be obtained. This peak, which is within two bandgaps, possesses a relative small full-width at half-maximum, about 11.5 nm. Moreover, the resonant wavelength of this sharp peak can be regulated by adjusting the relative depths of N asymmetrical teeth. These results that we acquire may have important application potential on high-density nanoplasmonic integration circuits.

A Systematic Method for Developing Harmonic Cantilevers for Atomic Force Microscopy

This paper proposes a method for developing harmonic cantilevers for tapping mode atomic force microscopy (AFM). The natural frequencies of an AFM cantilever are tuned by inserting gridiron holes with specific sizes and locations, such that the higher order resonance frequencies can be assigned to be integer harmonics generated by the nonlinear tip–sample interaction force. The cantilever is modeled using the vibration theory of the Timoshenko beam with a nonuniform cross section. The designed cantilever is fabricated by modifying a commercial cantilever through focused ion beam (FIB) milling. The resonant frequencies of the designed cantilever are verified using a commercial AFM.

Suppression of wolf-tone based on equivalent circuit model

Large size bowed stringed instruments, such as cello can pose undesired phenomenon called “wolf-tone” when you play at the specific pitch. When it occurs, a body strongly vibrates and a bow leaps on a string continuously. So, we are trying to figure out the cause of the wolf-tone and control it effectively. Thus, we devised “body-string coupled model” where body and string are coupled at bridge, and “bowed-string model” which expresses the relation between frictional force and relative speed, as it is called “stick and slip motion.” We simulated using finite-difference time-domain method and figured out the result that reproduces particular string motion called “Helmholz motion.” In addition, we set two parameters, speed of bow and pressure of bow, and calculated sound wave, oscillation mode, and the number of stick and slip. Then, we got the result of some existence ranges for wolf-tone. On this simulation, we added a small resonator in order to suppress the specific resonance mode which provides wolf-tone and observed wave forms. Based on these simulation results, we verified its effect experimentally on a real instrument.

Linear stability and resonance of triangular equilibrium points in elliptic restricted three body problem with radiating primary and triaxial secondary

The present paper studies the linear stability of the triangular equilibrium points of the system. The system comprises of a radiating primary and a triaxial secondary in elliptic restricted three body problem. The existence of third order resonances has been shown and the linear stability has been analyzed for these resonance cases. For the resonance case, and , the conditions of the linear stability are satisfied and the system is stable. But, for the resonance cases and the system is unstable.

A Triple-Band Voltage-Controlled Oscillator Using Two Shunt Right-Handed 4th-Order Resonators

A triple-band (TB) oscillator was implemented in the TSMC 0.18 ㎛ 1P6M CMOS process, and it uses a cross-coupled nMOS pair and two shunt 4SUPth/SUP order LC resonators to form a 6SUPth/SUP order resonator with three resonant frequencies. The oscillator uses the varactors for band switching and frequency tuning. The core current and power consumption of the high (middle, low)- band core oscillator are 3.59(3.42, 3.4) ㎃ and 2.4(2.29, 2.28) ㎽, respectively at the dc drain-source bias of 0.67V. The oscillator can generate differential signals in the frequency range of 8.04-8.68 ㎓, 5.82-6.15 ㎓, and 3.68-4.08 ㎓. The die area of the triple-band oscillator is 0.835 × 1.103 ㎟.

Quasiperiodic galloping of a wind-excited tower near secondary resonances of order 2

Quasiperiodic galloping of a wind-excited tower under unsteady wind is investigated analytically near secondary (sub/superharmonic) resonances of order 2 considering a single degree-of-freedom model. The case where the unsteady wind develops multiharmonic excitations consisting of the two first harmonic terms is examined. We perform two successive multiple scale methods to obtain analytical expressions of a quasiperiodic solution and its modulation envelope near the secondary resonances. The influence of unsteady wind on the quasiperiodic galloping and on the frequency of its modulation is examined for different cases of wind excitation. The results show that the quasiperiodic galloping onset and its modulation envelope can be influenced, depending on the activated resonance and the harmonic component induced by the unsteady wind. It is also shown that the frequency of the quasiperiodic galloping is higher near the 2-superharmonic resonance in all cases of wind excitation.

Design of Wideband Bandstop Frequency-Selective Structures Using Stacked Parallel Strip Line Arrays

We present a novel design procedure to implement wide bandstop frequency-selective structures using the periodic arrays of vertically stacked parallel strip lines (PSLs). The proposed structures employing the PSLs can simplify their design through equivalent circuit models. Three structures are designed based on the simple equations to demonstrate the proposed procedure. The first structure features an independent design of the air and substrate regions, allowing the use of higher order resonances to extend the bandwidth. The second structure employs a cascaded array, and the third represents a hybrid of both the first and second structures. Design examples have been provided for each proposed structure, achieving −10 dB fractional bandwidths of 78%, 100%, and 137% for the first, second, and third structures, respectively. The operating principles and the design procedures are explained along with the experimental verification for the first two structures.

Characteristics of a dynamic atomic force microscopy based on a higher-order resonant silicon cantilever and experiments

Abstract In order to improve the sensitivity and scanning speed of the dynamic AFM, a surface scanning method using higher-order resonant cantilever is adopted and investigated based on the higher-order resonance characteristics of the silicon cantilever, and the theoretical analysis and experimental verification on the higher-order resonance characteristics of the corresponding dynamic AFM cantilever are given. In this method, the cantilever is excited to oscillate near to its higher-order resonant frequency which is several times higher than that of the fundamental mode. Then the characteristic changes a lot compared with the first-order resonant cantilever. Because of the changes of the quality factor, amplitude and the mode shape of the cantilever, the higher-order resonant AFM gets higher sensitivity and scanning speed. Based on the home-built tapping-mode AFM experiment system, the resolution and the response time of the first and second order resonance measured by experiment are respectively: 0.83 nm, 0.42 nm; 1265 μs, 573 μs. The higher-order resonance cantilever has higher sensitivity and the dynamic measurement performance of the cantilever is significantly improved from the experimental results. This can be a useful method to develop AFM with high speed and high sensitivity. Besides above, the surface profile of a grating sample and its three-dimensional topography are obtained by the higher-order resonant mode AFM.

Fabrication and optical measurement of double-overlapped annular apertures

We demonstrate double-overlapped annular aperture (DOAA) arrays fabricated in a gold film via focused ion beam milling. The high order resonance modes of DOAA are investigated both theoretically and experimentally. Polarization dependency is observed for DOAA arrays and lower order resonance modes in the mid-infrared range exhibit extraordinary optical transmission and dependency on geometric parameters.

중형 컨테이너 운반선 축계장치의 선미관 선수베어링 설치 유무에 따른 횡진동 사례 연구

At the initial stage of propulsion shaft design, in line with shaft alignment, an intensified consideration of lateral vibration is needed to verify its operational safety. Recently the alignment problem affecting the lateral vibration has been becoming issues. However, the theoretical method of forced lateral vibration analysis is not cleary established so far and it is about to simply limited among the classification societies and international standards to avoid the blade natural frequency resonance cpm outside of of engine rpm at MCR. On the other hand, longer center distance between each support bearing shows an affirmative result normally in shaft alignment analysis whereas the blade order resonance speed may cause lowering near the limitation in the aspect of lateral vibration. Therefore, it is required careful attention to engineers as described above. As a method to solve the problem, it is mainly considered that remove forward stern tube bearing. In this paper, based on a medium size container ship case, theoretical study was carried out in the context of the forward stern tube bearing. The various effects and functions of forward stern tube bearing are reviewed and evaluated. Then an guidance note to lead the conclusion is proposed.

Interplay of space-charge fourth order resonance and envelope instability

Since the finding of the space charge fourth order 4σ=360° resonance [Jeon et al., 2009 [3]], studies have been carried out to better understand the fourth order resonance and the envelope instability in high intensity linear accelerators. The questions remained unanswered under what conditions the envelope instability is excited or suppressed following the development of the fourth order resonance. Simulations suggest that the variation of σo and σ along the linac, the halo particles and the resonance islands of the fourth order resonance play an important role in exciting or suppressing the envelope instability after the fourth order resonance is manifested for initially well-matched beams. Here σ(σo) is the depressed (zero-current) phase advance per cell. The envelope instability is excited from the mismatch generated by the fourth order resonance, 1) when σo is maintained approximately constant or increases along the linac with σo>90° and 2) when the extent of the fourth order resonance shrinks, as σ increases approaching 90°. On the other hand, when σ stays almost constant (maintaining the fourth order resonance) or when σo decreases and gets close to 90° (getting out of the envelope instability), the envelope instability is suppressed and the halo particles formed by the fourth order resonance preserves a four-fold structure in the phase space.

Giant in-particle field concentration and Fano resonances at light scattering by high-refractive-index particles

A detailed analytical inspection of light scattering by a particle with high refractive index m+i\kappa and small dissipative constant \kappa is presented. We have shown that there is a dramatic difference in the behavior of the electromagnetic field within the particle (inner problem) and the scattered field outside it (outer problem). With an increase in m at fix values of the other parameters, the field within the particle asymptotically converges to a periodic function of m. The electric and magnetic type Mie resonances of different orders overlap substantially. It may lead to a giant concentration of the electromagnetic energy within the particle. At the same time, we demonstrate that identical transformations of the solution for the outer problem allow to present each partial scattered wave as a sum of two partitions. One of them corresponds to the m-independent wave, scattered by a perfectly reflecting particle and plays the role of a background, while the other is associated with the excitation of a sharply-m-dependent resonant Mie mode. The interference of the partitions brings about a typical asymmetric Fano profile. The explicit expressions for the parameters of the Fano profile have been obtained "from the first principles" without any additional assumptions and/or fitting. In contrast to the inner problem, at an increase in m the resonant modes of the outer problem die out, and the scattered field converges to the universal, m-independent profile of the perfectly reflecting sphere. Numerical estimates of the discussed effects for a gallium phosphide particle are presented.

ORBITAL STABILITY OF MULTI-PLANET SYSTEMS: BEHAVIOR AT HIGH MASSES

ABSTRACT In the coming years, high-contrast imaging surveys are expected to reveal the characteristics of the population of wide-orbit, massive, exoplanets. To date, a handful of wide planetary mass companions are known, but only one such multi-planet system has been discovered: HR 8799. For low mass planetary systems, multi-planet interactions play an important role in setting system architecture. In this paper, we explore the stability of these high mass, multi-planet systems. While empirical relationships exist that predict how system stability scales with planet spacing at low masses, we show that extrapolating to super-Jupiter masses can lead to up to an order of magnitude overestimate of stability for massive, tightly packed systems. We show that at both low and high planet masses, overlapping mean-motion resonances trigger chaotic orbital evolution, which leads to system instability. We attribute some of the difference in behavior as a function of mass to the increasing importance of second order resonances at high planet–star mass ratios. We use our tailored high mass planet results to estimate the maximum number of planets that might reside in double component debris disk systems, whose gaps may indicate the presence of massive bodies.

Sensing Application in Fano Resonance With T-Shape Structure

A T-shape plasmonic structure, consisting of a stub resonator coupled with bus waveguide and cavity, has been investigated numerically and theoretically. Due to the near-field coupling mechanism between bright and dark modes, plasmon induced transparency can be observed in transmission spectrum. Moreover, it is demonstrated theoretically that the first order resonance mode can exist or not in the cavity by adjusting lateral displacement ( S ), which leads to the appearance or disappearance of the narrow transmission dip together with a steep Fano resonance in reflection spectrum. The effects of different parameters on a figure of merit (FOM) are investigated in detail. In sensing applications, the T-shape structure yields a sensitivity of ∼1090 nm shift per refractive index unit and a FOM of 33340. The results indicate that the width of cavity ( w c) is more sensitive than the distance ( g ) and length ( L ) for FOM. The transparency and Fano resonance effects may have potential applications in optical switch, slow-light devices, and nano sensor in highly integrated optical circuits.