Resonance Frequency Range Research Articles

Bioinspired Multiresonant Acoustic Devices Based on Electrospun Piezoelectric Polymeric Nanofibers.

Cochlear hair cells are critical for the conversion of acoustic into electrical signals and their dysfunction is a primary cause of acquired hearing impairments, which worsen with aging. Piezoelectric materials can reproduce the acoustic-electrical transduction properties of the cochlea and represent promising candidates for future cochlear prostheses. The majority of piezoelectric hearing devices so far developed are based on thin films, which have not managed to simultaneously provide the desired flexibility, high sensitivity, wide frequency selectivity, and biocompatibility. To overcome these issues, we hypothesized that fibrous membranes made up of polymeric piezoelectric biocompatible nanofibers could be employed to mimic the function of the basilar membrane, by selectively vibrating in response to different frequencies of sound and transmitting the resulting electrical impulses to the vestibulocochlear nerve. In this study, poly(vinylidene fluoride-trifluoroethylene) piezoelectric nanofiber-based acoustic circular sensors were designed and fabricated using the electrospinning technique. The performance of the sensors was investigated with particular focus on the identification of the resonance frequencies and acoustic-electrical conversion in fibrous membrane with different size and fiber orientation. The voltage output (1–17 mV) varied in the range of low resonance frequency (100–400 Hz) depending on the diameter of the macroscale sensors and alignment of the fibers. The devices developed can be regarded as a proof-of-concept demonstrating the possibility of using piezoelectric fibers to convert acoustic waves into electrical signals, through possible synergistic effects of piezoelectricity and triboelectricity. The study has paved the way for the development of self-powered nanofibrous implantable auditory sensors.

Micro-metamaterial antenna characteristics using microring embedded silver bars

A unique micro-metamaterial antenna for light and microwave wavelength conversion is proposed, where the antenna has the form of a panda ring which consists of the mu negative metamaterial silver bars embedded at the microring center. The micro-metamaterial antenna characteristics are investigated, where the antenna resonance frequency and frequency range of 1.60 THz and 1–2.2 THz are achieved. The radiation pattern of the micro-metamaterial antenna is plotted, where the obtained gain and directivity of the antenna are − 8.13 dB. The optimum antenna radiation efficiency is 1 when the antenna has dissipative loss is neglected. The micro-metamaterial antenna can be used as a converter between light and microwave, which is useful for a wavelength converter device.

Modeling and performance analysis of single fiber ring incorporated with fiber Bragg grating

The mathematical model of an optical ring resonator (RR) configuration using a single directional optical coupler (DOC) with a uniform fiber Bragg grating (FBG) incorporated and an RR configuration using two DOCs with an FBG incorporated is developed in the Z-domain. The developed mathematical model is used for the evaluation of transmission response. Spectral characteristics in terms of peak transmittance, resonant frequency, and free spectral range are determined for a single fiber ring configuration using two DOCs with an FBG incorporated. The results are found to be in very close agreement with measured values. The transmission characteristic of the single waveguide structure comprising a ring of length 2 mm enclosing a Bragg grating is analyzed. By properly optimizing the grating reflectivity and power coupling ratios of the coupler, a narrow full width at half maximum of 4.72 GHz that is around 78 times sharper than the normal FBG resonance is obtained. Further narrowing of the spectral width is achieved by increasing the RR length. The grating lengths are chosen judiciously to minimize the side peaks. The group delay and dispersion characteristics are addressed.

Advanced Film-Type Acoustic Reflector Inspired by Helmholtz Resonator

Sound waves propagate in a manner in which energy is transmitted by adjacent molecules in the medium. These adjacent molecules exhibit inherent sound wave characteristics, such as height and wavelength, depending on the sound frequency. The Helmholtz resonator, one of the well-known acoustic elements, comprises a neck and a cavity, and features a resonance at a specific frequency related to structural dimensions. The acoustic characteristics of the Helmholtz resonator can be explained by a lumped spring-mass system in mechanical engineering; the resonant frequency can be calculated with the same analysis. The Helmholtz resonator is widely used as an acoustic filter as it can re-radiate sound waves with the opposite phase and significantly attenuate the original sound wave in the resonance frequency range. In this study, we fabricated a Helmholtz resonator-inspired film-type acoustic absorber (FAA), comprising a microscale resonator array made with polydimethylsiloxane (PDMS). Through acoustic attenuation experiments, the FAA revealed that the novel attenuation values reached up to 36.3 dB mm-1. Additionally, a continuous fabrication of the FAA was achieved via a custom-built roll-type equipment.

Highly stretchable and mechanically tunable antennas based on three-dimensional liquid metal network

We develop a class of stretchable dipole antennas based on embedding three-dimensional liquid metal network into an elastically soft elastomer as conductive branches, which can be highly stretched up to a strain of 300% while presenting high-quality reflection coefficient around −30 dB and a wide range of tunable resonant frequency from 1.55 to 0.45 GHz simultaneously. Neither mechanical damage nor performance degradation was observed during 100 stretch-release cycles under 100% strain for the antennas. The high electrical conductivity and deformation reversibility of the liquid metal, super stretchability of the soft elastomer and protection from the rigid layer are responsible for such a unique performance, enabling potential application for wireless strain sensors.

Skin-Type Proximity Sensor by Using the Change of Electromagnetic Field

This article presents a sensor, called a skin-type dual proximity sensor (STPS) that can provide distance information in the form of impedance between a sensor and an approaching object before the collision. Meanwhile, a new method regarding the selection of the resonant frequency range for optimizing the measured distance is validated. The sensor adopts the combined sensing principle of inductive-capacitive proximity sensing. STPS can be fabricated with various dimensions and shapes, and easily attached to robot surfaces. Represented by the series of sensors studied with the dimensions of 100 × 100 × 2.75 mm, the proposed sensor can detect an approaching human body up to 300 mm away. In this article, sensor system modeling and simulation are conducted, followed by fabrication and signal processing methods. Finally, the performances of the sensor are experimentally validated, thoroughly analyzed concerning various parameters, and demonstrated with the collaboration between human and robots.

Tunable, multi-modal, and multi-directional vibration energy harvester based on three-dimensional architected metastructures

Conventional vibration energy harvesters based on two-dimensional planar layouts have limited harvesting capacities due to narrow frequency bandwidth and because their vibratory motion is mainly restricted to one plane. Three-dimensional architected structures and advanced materials with multifunctional properties are being developed in a broad range of technological fields. Structural topologies exploiting compressive buckling deformation mechanisms however provide a versatile route to transform planar structures into sophisticated three-dimensional architectures and functional devices. Designed geometries and Kirigami cut patterns defined on planar precursors contribute to the controlled formation of diverse three-dimensional forms. In this work, we propose an energy harvesting system with tunable dynamic properties, where piezoelectric materials are integrated and strategically designed into three-dimensional compliant architected metastructures. This concept enables energy scavenging from vibrations not only in multiple directions but also across a broad frequency bandwidth, thus increasing the energy harvesting efficiency. The proposed system comprises a buckled ribbon with optional Kirigami cuts. This platform enables the induction of vibration modes across a wide range of resonance frequencies and in arbitrary directions, mechanically coupling with four cantilever piezoelectric beams to capture vibrations. The multi-modal and multi-directional harvesting performance of the proposed configurations has been demonstrated in comparison with planar systems. The results suggest this is a facile strategy for the realization of compliant and high-performance energy harvesting and advanced electronics systems based on mechanically assembled platforms.

On the mechanical behavior of a wide tunable capacitive MEMS resonator for low frequency energy harvesting applications

We present a method for tuning the resonance frequency of a comb resonator using a combination of mechanically softening and hardening springs in order to achieve a high tuning range of resonant frequency. The nonlinear behavior of the structure is due to an angle in the main beam of a crab-leg flexure. Theoretical and simulation results are done to analyze the linear, quadratic, and cubic stiffness as well as frequency changes of the comb drive actuators. The frequency response of the resonator is achieved using the Lindstedt-Poincare perturbation technique. In order to validate the theoretical analysis, the results are compared with simulation results obtained by COMSOL software.

Effect of mechanical activation and ferritization on the phase composition of W-type hexaferrites obtained by the method of self-propagating high-temperature synthesis

Hexagonal oxide W-type ferrimagnetic powders (BaCo0.7Zn1,3Fe16O27) are obtained by the method of self-propagating high-temperature synthesis (SHS) in combination with preliminary or further mechanochemical activation in a high-energy unit and ferritization. The data on the phase composition, structural parameters and fundamental magnetic properties of synthesized ferrimagnetic used to create effective absorbers of electromagnetic radiation in the range of natural ferrimagnetic resonance frequencies are presented. Dispersion of the SHS product is found to significantly affects the value of the effective constant of magnetic crystallographic anisotropy. To explain this fact, a model that considers the contribution to magnetic anisotropy from magnetoelastic interaction and a perturbed near-surface layer, which are additive, is used. SHS with further mechanical activation and fine grinding shows that the mechanical treatment of the SHS product in a high-energy unit (planetary mill) is a way of controlling the magnetic properties of oxide hexagonal ferrimagnetic and, in this sense, affects like chemical doping

The anti‐icing and deicing robot system for electricity transmission line based on external excitation resonant

Aiming at the problem of off‐line deicing in overhead transmission lines, such as poor continuity of power supply and possible damage of lines caused by over‐thick deicing, a new online anti‐icing and deicing method based on external excitation resonance is proposed. The theoretical basis of the external excitation resonance to anti‐icing and deicing is established. Then the modal characteristics of the external excitation resonance are determined through the modal analysis of the ice‐coated transmission lines, and the reasonable frequency range of the external excitation resonance is obtained. According to the theoretical analysis and calculation results, the anti‐icing and deicing robot system is designed by the external excitation resonance. Intelligent video technology is used to detect the icing condition of transmission lines in real time, and the vibration frequency range of transmission lines is analyzed and calculated. The vibration frequency is adjusted through the real‐time tracking of the resonance feedback mechanism to ensure the continuity of the resonance working state, so as to effectively realize the efficient anti‐icing and deicing of the transmission lines with the thickness of 1–3 mm at the initial icing stage. Finally, the parameters of the key components of the system are calculated and determined, and the related influencing factors are analyzed. A new deicing theory based on anti‐icing theory is proposed, and specific engineering measures are given. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Tuning of a wide range of low resonance frequencies by a novel multi-resonant piezoelectric energy harvester

The power generation from environment vibrations through piezoelectric energy harvesting devices gained a huge research attention because of its ability to provide consistent power source to the wireless sensor networks. In recent years, researchers are attracted towards multi-resonant piezoelectric energy harvesters because of their wide operating bandwidth. This paper introducing a novel multi-resonant piezoelectric energy harvester that consisting two L-shaped and one straight branched beam along with proof masses on their free ends. The proposed device is capable to provide maximum peak of its output response at three close resonant frequencies. The main emphasis of the present paper is towards analyzing the geometry of L-shaped branched beams in view of tune up the three fundamental resonant frequencies within 10 Hz along with achieving first and third higher mode frequencies below 100 Hz. This study has been carried out by eigen frequency analysis using COMSOL multiphysics software under 0.2 g base acceleration excitation. It has been optimized from the study that the three close resonant frequencies have been reduced down within 10 Hz range by increasing the width of vertical part of L-shaped branched beams.

Eigenvalue Analysis and Behavioural Common-Mode Equivalent Circuit for an Asymmetric Active Phase Converter

A common-mode (CM) filter for a reduced switch active phase converter (APC) is proposed in this article for mitigation of switching frequency, and higher order CM current (CMC) injected into the grid. Due to asymmetry of the APC topology, a mixed-mode analysis of the differential-mode (DM) and CM components becomes essential. The presented state-space approach for the converter analysis captures the mixed-mode behavior of the APC. The eigenvalue analysis of the system shows that the inclusion of the proposed CM filter does not affect the existing DM APC system poles. Hence, the CM filter does not affect the APC control structure. This work also introduces an equivalent behavioral circuit which simplifies the CM filter component selection. This article provides a design methodology for the selection of the CM filter components by identifying the range of CM resonance frequencies. This design method results in active damping of the CM resonance without any additional control loop. The simulation results validate the behavioral CM equivalent circuit. The experimental validation is carried out on a laboratory APC prototype feeding a three-phase 3 hp induction motor from a single-phase grid. The measured CM voltages and currents validate the efficacy of the proposed CM filter for the APC.

Passive wideband concentric rings resonator for vocal cords abnormalities detection: Application on larynx cancer pathologies.

This work addresses the study and design of a diagnostic device consisting of a thin-film sensor array based on 8-mm concentered rings, acting as an autonomous acoustic sensor covering a wide range of resonance frequencies (0.1 KHz-2 MHz). In addition to its advantageous shape, this device integrates both the active vibratory element and the embedded electronics dedicated to coding, control, and analysis. The results show that the experimental device could be the basis of a telemedical platform for the objective assessment and monitoring of chronic laryngeal dysphonia through the spectro-temporal analysis of the vibration of the vocal cords. Furthermore, this non-invasive, non-intrusive protocol does not require the physical cooperation of the patient.

Research on Dynamic Modeling and Parameter Influence of Adaptive Gun Head Jet System of Fire-Fighting Monitor

The jet medium of the adaptive gun head jet system of the fire-fighting monitor is generally a mixture of air and water. During the operation, the equivalent stiffness of the jet fluid fluctuates periodically or randomly due to the pressure pulsation of the jet system and the external excitation such as wind, thus the dynamic behavior of the adaptive gun head jet system of the fire-fighting monitor has typical nonlinear characteristics. In this paper, based on the assumption that the equivalent stiffness of the fluid fluctuates in type of simple harmonic motion, a nonlinear dynamic model of the jet system is established, and the model is solved by the multi-scale method. The influence of design parameters such as fluid pulsation frequency, air inlet rate and fluid pressure on the amplitude of the main resonance and combined resonance of the jet system is analyzed. Results show that the existence of the fluid pulsation frequency increases the resonance frequency range of the jet system. As to the influence of design parameters on the dynamic characteristics of the jet system, from the point of view of amplitude change, the air inlet rate has the greatest impact on the main resonance, and the fluid pulsation frequency has the dominant influence on the combined resonance. This research can provide theoretical support for the dynamic optimization of the adaptive gun head jet system of the fire-fighting monitor.

Miniature microstrip antenna for IoT application

Wireless technology is greatly influenced by the advanced technological development of the antenna. With the rapid expansion of Internet of Things (IoT) application in the modern communication system, the demand for micro antennas is increasing. Microstrip patch antennas are generally used in IoT applications due to itscompatibility. The key benefit of the microstrip antenna is that it allows easy integration into IoT devices. Thus, in this work, rectangular microstrip patch antenna is designed and the performance was analysed. In this work,the antenna resonant frequency range was 100 MHz and 5.8 GHz, which is appropriate for IoT application was used. The antenna was designed with FR-4 substrate material. For this work, CST software (version 2014) was used as simulation software. In this work, two types of antenna were designed, which was conventional microstrip antenna and optimized microstrip antenna containing U-shaped structure. The performance of these two antennas was compared in terms of bandwidth, gain and return of loss. The key results of this work showed that the optimized U-shaped antenna improved the bandwidth from 134.1 MHz to 167.6 MHz, gain from 1.83 dB to 2.54 dB and return of loss-20.32 dB to −26.56 dB compared to the conventional antenna. In addition, the optimized antenna achieved operating frequency of 5.755 GHz, which is suitable for IoT applications.

Multi-Tuned Radiofrequency Coil Using Microfluidically Tunable Capacitor for Magnetic Resonance Imaging/Spectroscopy at 7-Tesla

Multi-nuclear magnetic resonance imaging and spectroscopy are considered valuable tools due to their capability of diagnosis and monitoring of several diseases. They require multi-nuclear Radiofrequency coils in order to interrogate the proton (1H) and other nuclei (X-nuclei) in the human body. Such coils provide anatomical images by acquiring (1H) spectra and metabolites information by acquiring spectra of X-nuclei. In addition, the high signal received from proton (1H) is used for B0 shimming purposes. However, the signal strength for these X-nuclei is too low. Hence, the signal-to-noise-ratio is low. The main advantages of using multinuclear Radiofrequency coils are that they speed up the imaging process and reduce the spatial positioning error that might arise when replacing the Radiofrequency coil in order to perform imaging of different nuclei. In addition, comfortable environment will be provided for patients by avoiding any inconvenience of moving out and asking to replace the coils. In this paper, a multi-tunable microstrip transmission line Radiofrequency coil has been designed by using microfluidically tunable Radiofrequency capacitor. This capacitor offers a wide range of capacitance tuning which extends between Cmin=1.76 pF and Cmax=48.7 pF. Hence, a wide range of resonant frequencies (fmin=75 MHz - fmax=298 MHz) can be offered by this coil in order to excite several nuclei at a field strength of 7-Tesla.

The effect of detuned wavelength in the dynamic performance of distributed feedback lasers operating at O band and C band

AbstractA comparison is presented between the experimental dynamic behavior of detuned AlInGaAs ridge waveguide distributed feedback lasers operating at O band and C band at two different temperatures. The nominal center wavelengths at 25°C for the set of devices studied were 1270, 1310, and 1550 nm. Preliminary static characterization of the samples showed consistent trends between wavelength detuning, characteristic temperature, and power output. For all set of samples, the characteristic temperature was substantially higher for the samples detuned to longer wavelengths (red) at room temperature. At the temperature of 85°C, a higher power efficiency was observed for those samples that thermally shifted nearer the peak optical gain. Resonance frequencies were extracted at 25°C and 85°C by means of electro‐optical transmission measurements and relative intensity noise measurements. The extracted values confirmed that at room temperature the samples detuned to shorter wavelengths (blue) showed the highest modulation efficiencies. At the temperature of 85°C, however, the wavelength and optical gain thermal shift makes those same samples to have the lowest resonant frequencies. The dynamic trends over temperature were clearer for the O band set of samples, while the detuning had a less pronounced effect at C band. The range of maximum resonance frequencies studied was from 12 to 14 GHz, which makes the devices suitable for uncooled communication applications at multi‐gigabit data rates.

A Design of Wide-range Frequency-tracking Ultrasonic Power Supply

Aiming at the problem that the frequency tracking range of commercial ultrasonic power supply on the market is narrow, which makes the load of ultrasonic power supply, a structure of transducer-horn-tool, difficult to match. This paper presents a kind of ultrasonic power supply based on TMS320F28335, which can track the frequency in a wide range(15-21kHz). The advantages, theory, software and hardware structure of the power supply are introduced, which can realize the functions of wide range frequency tracking, power regulation, human-computer interaction and so on. Experiments show that the power supply can well match the ultrasonic vibration load with a wide range of resonant frequencies, and has good human-computer interaction function.

One-Dimensional Non-Uniform Dielectric Structure as Tunable Resonator

The paper presents research on the composite dielectric resonators. This type of resonator consists of dielectric parts, which can move with respect to each other using an external actuator. The air discontinuity between dielectric parts perturbs the electromagnetic field of the resonator and as a result, shifts resonance frequency. As an analytical solution for this kind of structure does not exist, most practical techniques resort to approximate numerical solutions. The electromagnetic field problem for an inhomogeneous dielectric structure consisting of two infinite plates separated by a dielectric layer with a different dielectric constant is solved rigorously. The problem is reduced to a nonlinear eigenvalues and vectors problem. The eigenvalues determine the resonant frequencies, and the vectors represent the electromagnetic field of the resonance structure. It is shown, that the resonant frequency of the basic LM -mode has a high sensitivity to the change of the air layer between dielectric plates. Displacement of the plates in a few percent of its thickness leads to a change in the resonant frequency by tens of percent, depending on the dielectric constant of the plate. The sensitivity of the resonant frequency shift and the tuning range increases as the dielectric constant grows up and the plate thickness decreases. Another factor affected on resonant frequency tuning sensitivity and range is the distribution of the electromagnetic field along the dielectric plate plane. The increase of the electromagnetic field variation in such directions leads to growing sensitivity but reducing the tuning range. Resonant frequencies of LE -mode are less sensitive to a displacement of resonator's parts. The main reason for such a difference is the direction of E -field in inhomogeneity regions. E -field of LM -modes is directed normally to the border between the dialectic plate and air, but the E -field of LE -modes is located parallel to the border. The correlation characteristics of the tuning with the geometric and electrophysical parameters of the plates were established. It has been shown, that resonance frequency tuning occurs without degradation of the resonator's unloaded Q -factor. Moreover, the Q -factor increases due to the redistribution of electromagnetic field energy into the air region where the loss is almost absent. It has been demonstrated, that the regularities for a one-dimensional inhomogeneous structure are valid for inhomogeneous cylindrical dielectric resonators.

Experimental observations of diurnal acoustic propagation effects in seagrass meadows on the Dongsha Atoll

Large regions with seagrass meadows have been discovered on Dongsha Atoll located in the South China Sea. The aim of this study is the estimation of acoustic propagation loss in the frequency range of individual bubble resonance due to the gas content of seagrass in seagrass meadows. Specifically, this study seeks to (a) investigate the attenuation of the mid-frequency (2-8 kHz) signal induced by the gas content in a seagrass meadow and (b) present the diurnal variation of sound attenuation. The results demonstrate that >40 dB diurnal variations of mid-frequency propagation loss was observed in shallow seagrass meadow region.