Resonant Frequency Band Research Articles

An Optimal Design of Compact Ring-Slot Antenna for a Rectenna System With Numerical Manipulation

An improved design of a compact ring-slot type antenna for a rectenna system, which has superior and controllable property in size, directivity, and harmonics suppression is proposed. The conventional ring-slot antenna is modified with the slits and side-cuts to control the resonant frequency band, the suppression band, and the creation of circular polarization. Seven design parameters are selected from the primary research and optimized using the particle swarm optimization method with a numerically manipulated fitness function. The proposed antenna shows desirable performances in simulation and also in measurement with a reduced size.

Frequency Preference Response to Oscillatory Inputs in Two-dimensional Neural Models: A Geometric Approach to Subthreshold Amplitude and Phase Resonance

We investigate the dynamic mechanisms of generation of subthreshold and phase resonance in two-dimensional linear and linearized biophysical (conductance-based) models, and we extend our analysis to account for the effect of simple, but not necessarily weak, types of nonlinearities. Subthreshold resonance refers to the ability of neurons to exhibit a peak in their voltage amplitude response to oscillatory input currents at a preferred non-zero (resonant) frequency. Phase-resonance refers to the ability of neurons to exhibit a zero-phase (or zero-phase-shift) response to oscillatory input currents at a non-zero (phase-resonant) frequency. We adapt the classical phase-plane analysis approach to account for the dynamic effects of oscillatory inputs and develop a tool, the envelope-plane diagrams, that captures the role that conductances and time scales play in amplifying the voltage response at the resonant frequency band as compared to smaller and larger frequencies. We use envelope-plane diagrams in our analysis. We explain why the resonance phenomena do not necessarily arise from the presence of imaginary eigenvalues at rest, but rather they emerge from the interplay of the intrinsic and input time scales. We further explain why an increase in the time-scale separation causes an amplification of the voltage response in addition to shifting the resonant and phase-resonant frequencies. This is of fundamental importance for neural models since neurons typically exhibit a strong separation of time scales. We extend this approach to explain the effects of nonlinearities on both resonance and phase-resonance. We demonstrate that nonlinearities in the voltage equation cause amplifications of the voltage response and shifts in the resonant and phase-resonant frequencies that are not predicted by the corresponding linearized model. The differences between the nonlinear response and the linear prediction increase with increasing levels of the time scale separation between the voltage and the gating variable, and they almost disappear when both equations evolve at comparable rates. In contrast, voltage responses are almost insensitive to nonlinearities located in the gating variable equation. The method we develop provides a framework for the investigation of the preferred frequency responses in three-dimensional and nonlinear neuronal models as well as simple models of coupled neurons.

Modal and Wind Vibration Analysis about Steel Chimney Outer Wall with a Spiral Guide Plate Based on Workbench

This paper analysis a steel chimney outer wall with a spiral guide plate. Through calculation the steel chimney structure modal, self-vibration and wind vibration frequency verify this steel chimney can reduce the wind load impact on the chimney and flange connection. Achieve a method of improved the strength of chimney structure. The chimney under wind load resonant frequency band is reduced effectively and obtained a more stable exterior structure, offered basis for steel chimney transform in wind vibration problem.

Noninvasive Osseointegration Analysis of Skull Implants With Proximity Coupled Split Ring Resonator Antenna

A novel technique for skull implant diagnostics is presented in this paper. Specially designed highly directive antenna is used for osseointegration analysis with respect to the dielectric profile variation of the implant. The extreme dielectric constant variation of implant and bone gives a high degree of discrimination in the resonant frequency of the antenna. Special care is taken in antenna design to give a perfect matching and to keep the resonant frequency band width for different background properties. The antenna simulated on three different substrates is fabricated and experimentally verified with phantom models.

2A26 A Bistable Mechanical Oscillator with Stoppers for Wideband Vibration Energy Harvesting(The 12th International Conference on Motion and Vibration Control)

This study concerns a piezoelectric vibration energy harvester consisting of a bistable nonlinear oscillator with hardening behavior designed to have wideband resonance characteristics. A vibration energy harvester is an energy-harvesting device that is designed to collect mechanical energy from vibrating objects which is ordinarily discarded as heat. A conventional energy harvester is composed of a linear oscillator. In this design, the natural frequency of the oscillator is matched with the dominant frequency of the vibration source and the mechanical Q factor is designed as large as possible in order to maximize the captured power. The large Q factor, however, bounds resonance in a narrow frequency band, therefore, the converted power decreases significantly if the dominant frequency of the source moves out of this band. This trade-off is recognized as one of the most significant issues in resonance-type vibration energy harvesters because the actual vibration sources present in the environment are likely to have fluctuations in their frequency components. In this paper, in order to mitigate the power-bandwidth trade-off, the resonance frequency band of the harvester is extended by introducing a bistable oscillator with mechanical stoppers which is designed to have widely changing stiffness from nearly zero to quite hard. The presented design enables the harvester to generate larger electric power in a wider frequency range, exploiting the given stroke limit. An oscillator design to improve the global stability by eliminating the hysteresis phenomenon is also presented.

Design and Implementation of Internal Multiband Loop Embedded Monopole Antenna for Mobile Handset

In this paper, we proposed an internal multiband loop embedded monopole antenna for mobile handset that could be used for smart phones. The proposed antenna has a volume of 40 mm(W) 15 mm(L) 5 mm(H), ground plane size is 40 mm(W) 80 mm(L), and covers the GSM900 (Global System for Mobile communications : 880-960 MHz), K-PCS (Korea-Personal Communications Service : 1750-1870 MHz), US-PCS (US Personal Communications Service : 1850-1990 MHz), WCDMA (Wideband Code Division Multiple Access : 1920-2170 MHz), Wibro (2300-2390 MHz), Bluetooth (2400-2483 MHz) and WLAN (Wireless Local Area Network : 2400-2483.5 MHz) bands for VSWR (voltage standing wave ration) less than 3. The proposed loop adding design at middle section of longest branch showed wide impedance bandwidth for the lowest resonance frequency band. The proposed antenna have a lowest resonance frequency band from 738 MHz to 1075 MHz for S 11 value of -6dB. A HFSS (High Frequency Structure Simulator) of the Ansys Corporation based on a finite element method is employed to analyze the proposed antenna in the design process and to compare the simulation and experimental results.

Preferred frequency responses to oscillatory inputs in an electrochemical cell model: Linear amplitude and phase resonance

We investigate the dynamic mechanisms of generation of amplitude and phase resonance in a phenomenological electrochemical cell model in response to sinusoidal inputs. We describe how the attributes of the impedance and phase profiles change as the participating physicochemical parameters vary within a range corresponding to the existence of stable nodes and foci in the corresponding autonomous system, thus extending previous work that considered systems close to limit cycle regimes. The method we use permits us to understand how changes in these parameters generate amplifications of the cell's response at the resonant frequency band and captures some important nonlinear effects.

Vibration signal demodulation and bearing fault detection: A clustering-based segmentation method

The resonance demodulation technique has been widely employed in vibration signal analysis. In order to construct a proper bandpass filter, the prior knowledge, i.e. the resonance frequency band of the mechanical system is required in the traditional demodulation method. However, as the collected vibration signal is often tainted by the background noise and interferences often with unknown frequency contents, it is difficult to identify the center frequency and the bandwidth of the filter. This paper introduces a clustering-based segmentation method to determine these parameters automatically. Envelope analysis is then applied to demodulating the vibration data. According to the simulated cases, the proposed approach is robust to Gaussian noise and interferences. Its effectiveness is further validated by applying it to detect rolling bearing faults based on experimental data.

Erratum to the article “Nonstationary Quasielectrostatic Radiation Field of Dipole Antennas in a Magnetized Plasma in the Resonance Frequency Band,” by E.A. Shirokov and Yu.V.Chugunov, Vol. 54, No. 7, pp. 463-473, December, 2011.

Erratum to the article “Nonstationary Quasielectrostatic Radiation Field of Dipole Antennas in a Magnetized Plasma in the Resonance Frequency Band,” by E.A. Shirokov and Yu.V.Chugunov, Vol. 54, No. 7, pp. 463-473, December, 2011.

Transmission Loss Reduction of Circular Terahertz Waveguide Using Dielectric–Lined Method

In this paper, the transmission loss reduction for circular terahertz waveguide is investigated using dielectric-lined method. As is well known, the guided terahertz radiation suffers from high transmission loss due to the increase of ohmic loss and the lack of dielectric materials which has sufficiently transparency. As the existence of transmission loss, the quality of communication is therefore affected thoroughly. Here, the modification of hollow circular metallic terahertz waveguide by coating the inner surface of waveguide walls using some dielectric material, i.e. polystyrene, called as dielectric-lined method is proposed to reduce the transmission loss. The investigation is performed at THz frequencies from 0.1THz to 1.0THz including the analysis of transmission loss for each resonance mode and frequency band. The result shows that the proposed method with 15μm thickness of polystyrene coating is successfully decreasing the transmission loss for the TE01 wave mode below 1dB/m with smaller amplitude of electric field around the inner surface of waveguide walls. Furthermore, the discussion of investigation results for diameter variation and different thicknesses of polystyrene coating is also presented.

EMD and Zoom Envelope Spectrum for Rolling Bearing Fault Diagnosis

ntrinsic mode function component (IMF) has been effectively decomposed by using empirical mode (EMD) decomposition method, and the high-frequency resonance frequency band the rolling bearing components is extracted. Then the high frequency component of the IMF is shifted to the lower frequency by using real frequency modulation principle, and a new envelope refining spectrum is obtained through the Hilbert transform after low frequency sampling. The method not only simplifies the design of band-pass filtering process but improves refinement computational efficiency of the envelope spectrum. The method verifies the correctness of the theory and practical method through the analysis of the fault diagnosis of rolling bearing inner ring experiment.

The design of a new sparsogram for fast bearing fault diagnosis: Part 1 of the two related manuscripts that have a joint title as “Two automatic vibration-based fault diagnostic methods using the novel sparsity measurement – Parts 1 and 2”

Rolling element bearings are widely used in rotating machines. An early warning of bearing faults helps to prevent machinery breakdown and economic loss. Vibration-based envelope analysis has been proven to be one of the most effective methods for bearing fault diagnosis. The core of an envelope analysis is to find a resonant frequency band for a band-pass filtering for the enhancement of weak bearing fault signals. A new concept called a sparsogram is proposed in Part 1 paper. The aim of the sparsogram is to quickly determine the resonant frequency bands. The sparsogram is constructed using the sparsity measurements of the power spectra from the envelopes of wavelet packet coefficients at different wavelet packet decomposition depths. The optimal wavelet packet node can be selected by visually inspecting the largest sparsity value of the wavelet packet coefficients obtained from all wavelet packet nodes. Then, the wavelet packet coefficients extracted from the selected wavelet packet node is demodulated for envelope analysis. Several case studies including a simulated bearing fault signal mixed with heavy noise and real bearing fault signals collected from a rotary motor were used to validate the sparsogram. The results show that the sparsogram effectively locates the resonant frequency bands, where the bearing fault signature has been magnified in these bands. Several comparison studies with three popular wavelet packet decomposition based methods were conducted to show the superior capability of sparsogram in bearing fault diagnosis.

Impedance of a Spacecraft-Borne Antenna in the Magnetospheric Plasma and Quasi-Equilibrium Noise EMF in the Lower-Hybrid Frequency Band

We present analytical and numerical estimations of the value and frequency dependence of the impedance and noise electromotive force (EMF) in the context of the conditions which correspond to the trajectories and parameters of the antennas borne by geophysical monitoring satellites. The estimations were obtained for two circular orbits at altitudes of 600 and 1200 km over the Earth’s surface in the frequency range from 20 to 120 kHz, which corresponded to the area of the lower-hybrid resonance, where a higher level of noise emissions is observed at the altitudes under consideration. It is shown that near the lower-hybrid resonance frequency, the real part of the antenna impedance is determined by the resonant “monopole” loss by radiation of quasipotential waves. In the nonresonant frequency band (at the frequencies below the frequency of the lowerhybrid resonance), the antenna reactance is determined by the transit loss, which is, however, low as compared with the resonant loss. When the noise was calculated, the medium was assumed to be a two-temperature plasma. The spectral density of the power of the noise EMF lies in the range $$ V_{\omega}^2\approx \left( {2-4} \right)\cdot {10^{-12 }}-{10^{-13 }}\;{V^2}\cdot H{z^{-1 }} $$ and is determined mainly by suprathermal electrons. In the nonresonant frequency band, the efficient temperature of noise radiation is equal to the temperature of the “cold” plasma component, and the antenna reactance is determined by the transit loss, i.e., the level of the noise EMF is low as compared with the EMF in the resonant frequency band.

Structure Design and Simulation Analysis of Multiple Micro Piezoelectric Cantilevers

In order to effectively capture the environment vibration energy, convert it into electricity and supply energy for the microelectronics devices, multiple micro piezoelectric cantilevers are designed. It is composed of more than one piezoelectric cantilever array, which broaden the resonant frequency band of the piezoelectric vibrator, and it can produce resonance or similar to the resonance in a frequency range. Compared to a single piezoelectric cantilever, multiple piezoelectric cantilevers can effectively broaden the resonant frequency and improve the piezoelectric power generation capacity. The simulation results show that the finite element method can provide important theoretical guidance for the structural design of multiple micro piezoelectric cantilevers.

LTE용 L형 슬롯 마이크로스트립 패치 안테나 설계

In this paper was The dielectric constant of 4.4 and thickness of 0.6mm FR-4 substrate were implanted including the L-Slot in microstrip patch antenna to design a microstrip patch antenna for LTE. The proposed antenna is compact and lightweight compared to existing antenna and This antenna can be used as transmission ommidirectional radiation pattern of propagation was compared to the input return loss than -10dB (VSWR 2:1) to allow communication from the resonant frequency band.

The automatic selection of an optimal wavelet filter and its enhancement by the new sparsogram for bearing fault detection: Part 2 of the two related manuscripts that have a joint title as “Two automatic vibration-based fault diagnostic methods using the novel sparsity measurement—Parts 1 and 2”

Rolling element bearings are the most important components used in machinery. Bearing faults, once they have developed, quickly become severe and can result in fatal breakdowns. Envelope spectrum analysis is one effective approach to detect early bearing faults through the identification of bearing fault characteristic frequencies (BFCFs). To achieve this, it is necessary to find a band-pass filter to retain a resonant frequency band for the enhancement of weak bearing fault signatures. In Part 1 paper, the wavelet packet filters with fixed center frequencies and bandwidths used in a sparsogram may not cover a whole bearing resonant frequency band. Besides, a bearing resonant frequency band may be split into two adjacent imperfect orthogonal frequency bands, which reduce the bearing fault features. Considering the above two reasons, a sparsity measurement based optimal wavelet filter is required to be designed for providing more flexible center frequency and bandwidth for covering a bearing resonant frequency band. Part 2 paper presents an automatic selection process for finding the optimal complex Morlet wavelet filter with the help of genetic algorithm that maximizes the sparsity measurement value. Then, the modulus of the wavelet coefficients obtained by the optimal wavelet filter is used to extract the envelope. Finally, a non-linear function is introduced to enhance the visual inspection ability of BFCFs. The convergence of the optimal filter is fastened by the center frequencies and bandwidths of the optimal wavelet packet nodes established by the new sparsogram. Previous case studies including a simulated bearing fault signal and real bearing fault signals were used to show that the effectiveness of the optimal wavelet filtering method in detecting bearing faults. Finally, the results obtained from comparison studies are presented to verify that the proposed method is superior to the other three popular methods.

Numerical Analysis of Dual Band Mirrored-F Antenna for WLAN and Mobile WiMAX Applications

The numerical simulation of a low-profile dual band mirroredF antenna for 3.5/5.5 GHz WiMAX and 5.2 GHz WLAN applications is proposed. It has a dimension of 29×14.5 mm and the two resonant modes of the antenna provide bandwidth of 13.8% (3.35 GHz-3.85 GHz) and 17.4% (4.9 GHz-5.85 GHz) with maximum gain of 3.36 and 7.35 dBi respectively. The peak values of return loss are -22.124 and -52.282 dB and VSWR varies between 1.83~1.17 and 1.004~1.9 at the lower and upper resonant frequency bands. In addition, the antenna also provides almost omnidirectional radiation characteristics and excellent impedance matching.

Global stabilization of high-energy response for a Duffing-type wideband nonlinear energy harvester via self-excitation and entrainment

This article presents a resonance-type vibration energy harvester with a Duffing-type nonlinear oscillator that can perform effectively in a wide frequency range. To mitigate the power-bandwidth trade-off in conventional linear harvesters, the resonance frequency band of the harvester is expanded by introducing a Duffing-type nonlinear oscillator in order to enable the harvester to generate larger electric power in a wider frequency range. Such a nonlinear oscillator, however, can have multiple stable steady-state responses in the resonance band with different levels of regeneration energy. In this study, the principle of self-excitation is utilized to destabilize the solutions, except for the highest energy solution. A load circuit with a switch between the conventional load circuit and a negative resistance circuit and the switching control law, which depends on the amplitude of the oscillator’s response, are introduced to impart the self-excitation capability in order to entrain the oscillator with the excitation only in the highest energy solution. Theoretical and numerical analyses are conducted to show that the proposed harvester can respond in a large amplitude in a wide frequency range, and a significant improvement in the regenerated power is achieved as compared to the one without self-excitation control.

Using appropriate IMFs for envelope analysis in multiple fault diagnosis of ball bearings

The traditional envelope analysis is an effective method for the fault detection of rolling bearings. However, all the resonant frequency bands must be examined during the bearing-fault detection process. To ameliorate the above deficiency, this paper presents a new concept based on the empirical mode decomposition (EMD) to choose an appropriate intrinsic mode function (IMF) for the subsequent envelope analysis. By virtue of the band-pass filtering nature of EMD, the resonant frequency bands of structure to be measured are captured in the IMFs. As impulses arising from rolling elements striking bearing faults modulate with structure resonance, appropriate IMFs are potentially able to characterize fault signatures, instead of always using IMF 1. In the study, dual- and triple-fault bearings are used to justify the proposed method and comparisons with the traditional envelope analysis are made.

Design, measurement, and characterization of dual‐band left‐handed metamaterials with combined elements

AbstractWe report on a new kind of planar left‐handed metamaterial with both simulations and experiments in this article. Dual electric and magnetic resonance frequency bands are experimentally realized by introducing two different metallic elements in one unit cell, which offers a convenient approach in building dual‐band or multiband negative‐index metamaterials. The effective electromagnetic parameters obtained from the measured S‐parameters indicate that negative refractive indexes are verified near 8.5 and 12 GHz with both negative permittivity and negative permeability. Field and current distribution at the dual resonances are also examined. At last, we calculated the radiated power of the magnetic dipole moments along y‐axis. The idea can help us to fabricate dual‐band or multiband metamaterial absorbers, filters, and antennas. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:493–497, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27399