Non-resonant Type Research Articles

Investigations on piezo actuator-based non-resonant type workpiece vibratory system for vibration-assisted micro-milling

Investigations on piezo actuator-based non-resonant type workpiece vibratory system for vibration-assisted micro-milling

Can Perfectly Electric Conducting Obstacles Modify the Permeability of Metamaterial? An Investigation Using Lorentz, Floquet, and Full-Wave Models

The Lorentz model shows that inclusion of perfectly electric conducting (PEC) obstacles in a host medium introduces both electric and magnetic polarizabilities that modify the permittivity and permeability tensors of the composite medium. On the other hand, the Floquet eigenmodal analysis shows that the PEC obstacles, while modify the permittivity tensor, have no effect on the permeability tensor. Interestingly, numerical results obtained from full wave analyses of metamaterial-slabs support the Floquet model. The source for the inaccuracy in Lorentz model is critically examined. Characteristic features of metamaterials made with non-resonant and resonant types of obstacles are investigated and the numerical results obtained from four independent models are compared and discussed.

Development of microwave technology of selective heating the components of heterogeneous media

The relevance of solving the technological problem of guaranteed inactivation of microflora by heating in liquid media and the preservation of their useful components, in particular, in wine materials, is substantiated. Traditional heat treatment with heating up to 70...75 °C leads to a deterioration in the properties of the medium due to the thermal decomposition of its useful components. Newer is the technology of heating by the energy of the microwave field in the working chamber. But its significant drawback is the formation of standing waves in the metal chamber, causing local zones of overheating in places of maxima and underheating in places of wave minima. The consequence of this is the deterioration of the chemical composition of products and unsatisfactory inactivation of microflora. The elimination of these disadvantages of microwave processing of media is proposed to be carried out in a non-resonant chamber developed by the authors. Selective heating in the new chamber is produced by the energy of a uniform microwave field. At the same time, there are no local overheating and underheating of products. The technical implementation of a non-resonant type chamber involves the concentration of field energy in the volume of production, the conversion of the ballast field energy into thermal energy and its utilization. The work includes theoretical substantiation and experimental confirmation of the advantages of the new technology compared to the traditional one. Selective heating of products in a non-resonant working chamber entails the possibility of reducing the temperature required for guaranteed inactivation of microflora by 25...30 °C. This helps to preserve the components of the product due to the absence of overheating and reduce energy costs. In addition, it provides: exclusion of harmful radiation from the working chamber; prevention of self-overheating of the generator and exclusion of the dependence of the energy efficiency of the chamber on the level of its loading with products.

A Decoupling Network for Resonant and Non-Resonant Sub-1 GHz MIMO Mobile Terminal Antennas With Improved Compactness and Efficiency

In this work, the design procedure of a new decoupling network for different antennas is presented for mobile terminals operating in the Sub-1 GHz band (from 0.698 to 0.96 GHz). To evaluate its applicability for different resonant and non-resonant antenna types, two antenna elements have been chosen to be decoupled using the proposed decoupling network: a printed inverted-F antenna and a capacitive coupling element antenna. Simulation and measurement results showed that the decoupling network offer promising improvements in terms of impedance matching, port isolation, envelope correlation coefficient (ECC), and total efficiency. In addition, the antennas are also investigated with the ergodic capacity, multiplexing efficiency, gain, and diversity gain (both calculated using maximal ratio combining technique). Due to the contribution of the decoupling network, the ECC of both types of multiple antennas are less than 0.3, with a 30 % improvement in total efficiency and an inter-element spacing miniaturization of 34 %.

Recent Progress on Ultrathin Metalenses for Flat Optics.

SummaryAs technology advances, electrical devices such as smartphones have become more and more compact, leading to a demand for the continuous miniaturization of optical components. Metalenses, ultrathin flat optical elements composed of metasurfaces consisting of arrays of subwavelength optical antennas, provide a method of meeting those requirements. Moreover, metalenses have many other distinctive advantages including aberration correction, active tunability, and semi-transparency, compared to their conventional refractive and diffractive counterparts. Therefore, over the last decade, great effort has been focused on developing metalenses to investigate and broaden the capabilities of metalenses for integration into future applications. Here, we discuss recent progress on metalenses including their basic design principles and notable characteristics such as aberration correction, tunability, and multifunctionality.

Nonlinear instability of interfacial waves in stratified laminar channel flow

The evolution of interfacial waves is investigated for a stratified laminar-laminar flow in a plane channel using numerical simulations based on the Volume of Fluid (VOF) method. Different nonlinear instability mechanisms that can promote saturation or rapid amplification of interfacial waves are investigated. Controlled disturbances are introduced at the interface between the two fluids, to assess five different scenarios of nonlinear interactions including harmonic excitation, subharmonic resonance, interaction between a short and a long wave, and two kinds of modulated wavepackets. Present simulations suggest that the same non-resonant type of wave interaction dominates the nonlinear stages of evolution in all the scenarios, for the fluid properties and parameters covered in this work. This mechanism involves the amplification of harmonics by quadratic nonlinearities and leads to the finite-amplitude saturation of interfacial waves, which results in a wavy flow. Reduced order models based on interaction of few wavelengths and described by the Stuart–Landau equation are proposed for the prediction of the nonlinear flow dynamics of laminar liquid-liquid two-phase flows.

Comparison between Resonance and Non-Resonance Type Piezoelectric Acoustic Absorbers.

In this study, piezoelectric acoustic absorbers employing two receivers and one transmitter with a feedback controller were evaluated. Based on the target and resonance frequencies of the system, resonance and non-resonance models were designed and fabricated. With a lateral size less than half the wavelength, the model had stacked structures of lossy acoustic windows, polyvinylidene difluoride, and lead zirconate titanate-5A. The structures of both models were identical, except that the resonance model had steel backing material to adjust the center frequency. Both models were analyzed in the frequency and time domains, and the effectiveness of the absorbers was compared at the target and off-target frequencies. Both models were fabricated and acoustically and electrically characterized. Their reflection reduction ratios were evaluated in the quasi-continuous-wave and time-transient modes.

Study of Energy Harvesting from Low-Frequency Vibration with Ferromagnetic Powder and Non-magnetic Fluid

The movement of the creature and the almost wave in the ocean is a low vibration of random energy with a frequency range of 0.1–10 Hz. Because of its low frequency, the opinion has been that electrical energy generation from this low-frequency wave motion through the electromagnetic induction method is difficult. In this study, an electrical generator was created by the electromagnetic induction method by putting a small mass of ferromagnetic powder in nonmagnetic fluid. A broadband vibration energy harvesting model was created in which vibrations are broadened through a multi-degree of freedom oscillation system using ferromagnetic powder. To generate electricity from low-frequency vibrations (1 Hz or less), a non-resonant type model was created by adding fluid to the ferromagnetic powder model and the simulation results confirmed using computational fluid dynamics by creating a working energy harvesting device.

A non-resonant sandwich type bidirectional stepping piezoelectric actuator driven by oblique two-dimensional trajectory: Design, analysis and experiment evaluation

Abstract This work proposed a non-resonant sandwich type bidirectional stepping piezoelectric actuator driven by an oblique two-dimensional trajectory. This trajectory was formed on the driving tip by compositing the longitudinal deformation of a PZT stack and the bending deformation of a PZT_B group. The longitudinal and bending deformations were employed to press and drive the runner, respectively. The configuration of the actuator was exhibited and its principles were illustrated. A static model of the bending deformation of this actuator was built. Finite element method was used to analyze the motion trajectory of driving tip. A prototype was fabricated to verify the feasibility and evaluate the output characteristics. Experiments denoted that the proposed actuator had coincident characteristics along forward and backward directions. The forward and backward velocities were tested as 154.2 μm/s and 152.7 μm/s when the voltages of PZT_B group and PZT stack were 210 Vp-p and 210 V0-p, respectively. The maximum output forces were tested as about 31.6 N and 31 N along two directions. The tested results also indicated that the proposed actuator could output precision motions with the minimum step sizes of 24 nm and 25 nm along forward and backward directions, respectively.

Design and experiment of a slender nonresonant linear piezoelectric motor based on bridge-type amplification mechanism

A miniature non-resonance type linear piezoelectric motor based on a mechanical bridge-type amplification mechanism has been developed. The slender motor measures 29 mm × 5 mm × 3.5 mm. The stator consists of a parallel bridge amplifier and two multilayer piezoelectric actuators. The working principle of the motor is analyzed, and the physical performance of the bridge amplification mechanism is obtained by a finite element analysis. A prototype of the motor is manufactured, and the model is verified by experiment, and the mechanical properties of the motor characterized. The test results show that when the phase difference between the two driving signals is 90°, the output driving force of the motor reaches its maximum. The motor speed increases linearly from 2.2 mm/s to 7.6 mm/s when the driving frequency ranges from 100 Hz to 1100 Hz under the conditions of peak driving voltage 140 V, bias voltage 70 V and holding force 2.2 N. The motor speed decreases with the increase of load. When the driving frequency is 900 Hz and the holding force is 6 N, the maximum driving force can reach 1.41 N.

A review of recent studies on non-resonant piezoelectric actuators

Abstract Various non-resonant piezoelectric actuators have been emerged in recent decades and they have been applied successfully in many industrial fields, such as medical apparatuses, optical instruments and semiconductor technologies. They are generally classified into three categories according to their different working principles: the direct drive type, the inertial drive type and the inchworm type, respectively. The main contribution of this work is to provide a comprehensive review of recent studies on the non-resonant type piezoelectric actuators. In this review, the operating principles, some representative designs, performance analyses and practical applications of each type of non-resonant piezoelectric actuators are provided. Finally, a summary is concluded and the future development perspectives of these non-resonant type piezoelectric actuators are discussed. This review contributes to giving a comprehensive understanding of the non-resonant type piezoelectric actuators. It also provides guidance on designing new piezoelectric actuators for improving their mechanical output performances.

Non-resonant type electromagnetic micro energy harvester using collision of steel ball

Non-resonant type electromagnetic micro energy harvester using collision of steel ball

Viscoelastic and acoustic characterization of polyurethane‐based acoustic absorber panels for underwater applications

ABSTRACTAcoustic absorbers that can have applications in a desired frequency band are a challenge often encountered in underwater acoustic absorber panel design. Polyurethane‐based sound absorbing composite panels were designed with the help of finite element method (FEM) modeling using COMSOL for material formulations that can give optimum performance of echo reduction (ER) with minimum thickness. Polyurethanes of different compositions were evaluated for their acoustic performance using FEM modeling and experimental validation of the modeling results was done. The frequency‐dependent modulus and damping properties were generated using dynamic mechanical analyzer and time–temperature superposition were performed to generate the material properties in the high frequency range (up to 25 kHz), which are significant for underwater acoustic detection applications and these data were used as inputs for modeling studies. Acoustic properties of the samples were experimentally evaluated using a water‐filled pulse tube in 2–15 kHz frequency range as well as in an acoustic tank test facility for bigger dimension panels. These are nonresonant type absorbers capable to overcome limitations arising from environmental factors such as high hydrostatic pressures and also they are effective over a broad range of frequency (500 Hz–15 kHz) with ER > 15 dB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47165.

Development of electrical generator using ferromagnetic powders and non-magnetic fluid

This paper reports a broadband vibration resonance model for vibration energy harvesting using ferromagnetic powders and suggested a non-resonance type device model by adding a non-magnetic fluid(water) to this device model to support frequencies lower than 10 Hz. The work builds on a vibration energy harvesting device reported at Mechanical Engineering Journal [1].In this study, because the electric generator can convert the reciprocating motion into electrical energy without rotary motion by ferromagnetic powders and non-magnetic fluid for the naturally occurring kinetic energy that is small such as the creature exercise, it may be said that this electricity generator is effective. We suggest that using ferromagnetic powders for broadband vibration and non-magnetic fluid for the low-frequency vibrations as devised in this study could be a breakthrough in solving the technical problems that arise in vibration energy harvesting.

Preparation of water-soluble asphalt carbon dots and hyperchromic effect to Cr (VI)

Water-soluble asphalt carbon dots (W-CDs) was prepared from medium - temperature coal tar pitch as raw material, via mixed acid oxidation, alkali solubilization and acid precipitation method. It was observed that as-prepared W-CDs were irregular particles with good water dispersibility and the particle size was controlled by the pH of the acid precipitation solution by a polarizing microscope. Infrared spectroscopy confirmed that the surface of the W-CDs was functionalized by hydrophilic and color-promoting functional groups, which had good water solubility; the thermal weight loss proved to be good thermal stability below 200°C; the fluorescence spectrum proved that the fluorescence emission peak position of the carbon dots appears red shift with increase of excitation wavelength, with fluorescence conversion property, and its emission light intensity decreases, belonging to non-resonant fluorescence type of direct jump fluorescence; UV spectrum proves that the addition of W-CDs can be chromium (VI) CrO42- content The detection limit was increased from milligram to microgram; the molar absorptivity of CrO42- was increased by 4 times. The experimentally optimized W-CDs-ultraviolet-viscometry method for measuring CrO42- conditions: W-CDs to chromium ratio of 8:2, pH of 8, hexamethylenetetramine as a surfactant, and the solution was allowed to stand at room temperature for 45 min.

Off-centered Double-slit Metamaterial for Elastic Wave Polarization Anomaly

The polarization anomaly refers to the polarization transition from longitudinal to shear modes along an equi-frequency contour of the same branch, which occurs only in some anisotropic elastic media, but the lack of natural materials exhibiting desired anisotropy makes its utilization impossible for potential novel applications. In this paper, we present a unique, non-resonant type elastic metamaterial made of off-centered, double-slit unit cells. We show that its wave polarization characteristics that determine the desired anomalous polarization for a certain application are tailorable. As an application, a mode converting wedge that transforms pure longitudinal into pure shear modes is designed by the proposed metamaterial. The physics involved in the mode conversion is investigated by simulations and experiments.

Local Area Radiation Sidelobe Suppression of Reflector Antennas by Embedding Periodic Metallic Elements Along the Edge Boundary

This communication presents a simple and useful technique to suppress the radiation sidelobe levels (SLLs) of reflector antennas by embedding reflecting elements around the edge boundary. Due to the fact that sidelobes mainly arise from the edge diffractions, the reflecting elements can alter the phase distribution of induced currents along the edge boundary, and therefore reduce the sidelobes through the destructive cancellation of fields radiated from these elements. The desired phases are found through the implementation of pattern synthesis technique such as genetic algorithm to optimize the SLLs. This technique of edge current phase alternation may be employed, in conjunction with using a tapered feed radiation to illuminate the reflector, to control both amplitudes and phases of edge currents. Thus, the edge diffraction mechanism may be better controlled to optimize SLLs. In this communication, both resonant and nonresonant types of metallic elements are implemented and compared to illustrate their characteristics of radiations in SLL suppression. This technique is particularly useful to suppress the SLLs within a local angular region. Numerical results based on the method of moment analysis are presented to validate the feasibility.

Near-field edge fringes at sharp material boundaries.

We have studied the formation of near-field fringes when sharp edges of materials are imaged using scattering-type scanning near-field optical microscope (s-SNOM). The materials we have investigated include dielectrics, metals, a near-perfect conductor, and those that possess anisotropic permittivity and hyperbolic dispersion. For our theoretical analysis, we use a technique that combines full-wave numerical simulations of tip-sample near-field interaction and signal demodulation at higher orders akin to what is done in typical s-SNOM experiments. Unlike previous tip-sample interaction near-field models, our advanced technique allows simulation of the realistic tip and sample structure. Our analysis clarifies edge imaging of recently emerged layered materials such as hexagonal boron nitride and transition metal dichalcogenides (in particular, molybdenum disulfide), as well as traditional plasmonic materials such as gold. Hexagonal boron nitride is studied at several wavelengths, including the wavelength where it possesses excitation of phonon-polaritons and hyperbolic dispersion. Based on our results of s-SNOM imaging in different demodulation orders, we specify resonant and non-resonant types of edges and describe the edge fringes for each case. We clarify near-field edge-fringe formation at material sharp boundaries, both outside bright fringes and the low-contrast region at the edge, and elaborate on the necessity of separating them from propagating waves on the surface of polaritonic materials.

Magnetoelectric Current Sensors.

In this work a magnetoelectric (ME) current sensor design based on a magnetoelectric effect is presented and discussed. The resonant and non-resonant type of ME current sensors are considered. Theoretical calculations of the ME current sensors by the equivalent circuit method were conducted. The application of different sensors using the new effects, for example, the ME effect, is made possible with the development of new ME composites. A large number of studies conducted in the field of new composites, allowed us to obtain a high magnetostrictive-piezoelectric laminate sensitivity. An optimal ME structure composition was matched. The characterization of a non-resonant current sensor showed that in the operation range to 5 A, the sensor had a sensitivity of 0.34 V/A, non-linearity less than 1% and for a resonant current sensor in the same operation range, the sensitivity was of 0.53 V/A, non-linearity less than 0.5%.

A flexible hybrid strain energy harvester using piezoelectric and electrostatic conversion

A new design of flexible energy harvester to utilize piezoelectric and electrostatic energy conversion mechanisms simultaneously from a single mechanical energy source is proposed. This non-resonant type harvester enables low-frequency mechanical inputs to be converted to electricity, and the polymeric structures make the harvester mechanically flexible, allowing it to be applied to non-planar surfaces. The fabricated harvester generated peak- and average power densities of 159 and 1.79 μW cm−2 respectively by piezoelectric conversion, and 52.9 μW cm−2 and 1.59 nW cm−2 respectively by electrostatic conversion from an input force of 1.2 N at 3 Hz. Considering its flexibility and ability to harvest mechanical inputs at frequencies below 3 Hz, low-frequency human movements could be a potential energy source for the proposed hybrid harvester to exploit.