Resonant Load Research Articles

Numerical and Experimental Research on Single-Valve and Multi-Valve Resonant Systems

Multiple valves in the pipeline system belong to obvious periodic structure distribution types. When a high-speed airstream flows through the pipeline valve, it produces obvious aero-acoustic and acoustic resonance. Acoustic resonant systems with single and six-pipe valves were investigated to understand the flow and acoustic characteristics using a numerical simulation method and testing method. The strongest acoustic resonance occurred at a specific flow velocity with a corresponding Strouhal number of 0.47 corresponding to the geometric parameters in the paper. Moreover, acoustic resonance occurred in a certain velocity range, rather than increasing with the increase of the velocity of the pipeline. This regular increase provided an important theoretical basis for the prediction of the acoustic resonant and ultimate acoustic load of a single-valve system. When the pipeline was attached with multiple valves and the physical dimension was large, the conventional aero-acoustics calculation results were seriously attenuated at high frequency; the calculation method involving a cut-off frequency in this paper was presented and could be used to explain the excellent agreement of the sound pressure level (SPL) below the cut-off frequency and the poor agreement above the cut-off frequency. A new method involving steady flow and stochastic noise generation and radiation (SNGR) was proposed to obtain better results for the SPL at the middle and high frequencies. The comparison results indicated that the traditional method of Lighthill analogy and unsteady flow could accurately acquire aerodynamic noise below the cut-off frequency, while the new method involving steady flow and SNGR could quickly acquire aerodynamic noise above the cut-off frequency.

Dynamic response to transverse loading of a single-layered tubular beam via a perturbation approach

A beam-like model is proposed to address nonlinear dynamic response of a thin pipe, under the action of a resonant transverse load. The mechanical model consists of a Timoshenko beam enriched with further kinematic and dynamic variables which, besides extension and bending, consistently describe local effects, related to ovalization and warping of the cross-section. The nonlinear equations of motions are derived via the principle of virtual work, and internal resonance between the global and local modes is addressed by the multiple scale method, after a Galerkin projection of the equations on the first significant modes. The softening behavior induced by the local deformation remarkably affects the asymptotic solution, which turns out to be in good agreement with that provided by numerical integration.

Implementation of left handed transmission lines based on waveguide TM modes

AbstractIn this article, a novel left‐handed (LH) waveguide transmission line with good filtering performance is proposed and implemented below the TM mode cutoff frequency. TM11 mode is employed and transmitted inside the waveguide. The LH passband is achieved by TM mode cutoff operation and complementary split‐ring resonator (CSRR) loading, which are able to provide negative μ and ε, respectively. It constitutes the main novelty here with the rectangular waveguide TM mode and CSRR to realize the LH characteristics, which has not been done before. Based on this passband, two bandpass filters with high‐selectivity are designed and fabricated. The measured results are in agreement with the simulated data. It shows a good LH passband below the cut‐off frequency and TM11 mode propagation is also detected at higher frequency above the cutoff.

Simple Design of a Wideband and Wide-Angle Insensitive Metamaterial Absorber Using Lumped Resistors for X- and Ku-Bands

We report a wideband and polarization-/wide-angle insensitive metamaterial absorber based on a symmetry structure associated with surface mount resistors. The proposed structure consists of a periodic array of a top metal symmetry resonator loading with four lumped resistors and a continuous metal ground plane separated by a dielectric substrate of FR-4. A prototype of the proposed absorber is fabricated and measured, confirming a good agreement between the measurement and simulation results. The proposed absorber shows polarization-insensitive behavior and the absorption response in a frequency range from 8-18 GHz covering the entire X- and Ku- bands with an absorptivity above 80$\%$ for a wide incident angle up to 40 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> for both transverse electric and transverse magnetic polarizations. Compared with the reported broadband absorbers using lumped resistors, our proposed absorber exhibits excellent characteristics in terms of compact and simple structure, high relative absorption bandwidth, and polarization and wide-incident insensitivity. Therefore, this design shows promising potential for both X- and Ku-band applications.

Simultaneous Detection of Multiple Surface Acoustic Wave Sensor Tags for Water Quality Monitoring Utilizing Cellular Code-Reuse Approach

A water quality monitoring application often requires the deployment of Internet-of-Things (IoT) sensors over a wide water body with communication links among them to transmit, receive the data, and then uplink it to the cloud for further analytics. Deployment of this kind requires battery-assisted IoT sensors which require monitoring the battery level and replacement when necessary. It is thus desirable to have battery-free sensor tags and a suitable communication infrastructure to obtain data. In this article, a system that facilitates obtaining sensed data, like pH, through passive sensor tags based on surface acoustic wave (SAW) technology and a cellular code-reuse scheme-based reader infrastructure is proposed. The reader in each cell is able to read multiple sensor tags simultaneously, which itself has been a challenge. The SAW sensor tags are appropriately proposed to be designed to be orthogonal to allow simultaneous detection and the cell range of reader-SAW sensor-tags communication is sought to be further enhanced through a resonant loading of interdigital transducer (IDT)-based reflectors.

Compact Band-Pass Filter Using Modified Ω-shaped Resonator and Source Load Coupling for Transmission Zero Improvement

Compact Band-Pass Filter Using Modified Ω-shaped Resonator and Source Load Coupling for Transmission Zero Improvement

Geometric layout optimization of a large aperture thin elliptical mirror’s axial and lateral support

For passive support of large aperture telescopes, geometric layout optimization of the support structure is one of the most critical tasks because it determines the deformation of the mirror under gravity, which affects the wavefront aberration and image quality of the system. Due to a lack of symmetry, the optimization of an elliptical mirror support can be much more complex compared with circular mirrors. We optimize the geometric layout of axial and lateral support for the tertiary mirror of the Thirty Meter Telescope (TMT). Based on a theoretical analysis of the whiffletree principle, a parametric model of axial support is established based on the multi-point constraint equation. The mirror deformation SlopeRMS of the tertiary mirror under vertical gravity is used as the optimization target of the support points. The axial support point position is optimized by means of a simulated annealing algorithm and a mirror-deformed post-processing script written in Python. The TMT tertiary mirror lateral support also uses the whiffletree structure, and its in-plane layout affects the system's resonant modal frequency and the maximum load at each point. According to the dynamic equation and the static principle, the lateral support optimization model is established. The first-order resonant frequency and maximum load of the support point are the objective function. Through optimization of the axial and lateral support, the overall mirror distortion of the system is improved.

Three-Phase AC–AC Converter With Diode Rectifier for Induction Heating Application With Improved Input Current Quality and Coil Modeling

In this article, a three-phase ac-ac resonant converter for an induction heating application is proposed. The system employs three coils in a coaxial arrangement, which is characterized using an resistive-inductive-capacitive (RLC) passive network. For obtaining the parameters of this network, a nonlinear regression from the experimental data was executed using the shuffled complex evolution optimization method, which stands out for its rapid convergence and for providing a well-structured and systematic search for the cost function minimization. The operation stages of the resonant converter are discussed in detail allowing to observe a zero voltage switching (ZVS) behavior for the resonant load inductive region. In addition, the converter operates at unitary power factor because of the smooth dc-link bus voltage and the input current filter. Finally, a 10-kW prototype was built to verify the theoretical analysis and the simulations. As from this comparison was established that the mutual inductance and stray capacitive effects were modeled accurately allowing to reproduce the induced voltages in the coils. Besides, it was corroborated that the coils arrangement influences in the distortion of the input currents, but this distortion can be minimized through the adequate selection of the switching phase angles.

A Novel Printed Monopole Antenna With A Tapered-line Resonator Loading

In this paper, a novel compact printed monopole antenna is presented. The antenna consists of a planar monopole antenna and a tapered-line resonator with inner coupled section, which works as a near-field resonant parasitic (NFRP) element. The resonant frequency can be decreased dramatically by the strong coupling between the resonator and the monopole antenna. Thus, the miniaturization of the antenna is realized. The simulated results show that the resonant frequency decreases from 2.98 GHz to 2.4 GHz and the electric length of the antenna is reduced from 0.32 λ to 0.25 λ by loading a tapered-line resonator as NFRP element. After theoretical analysis is presented, sample antenna is manufactured and measured to verify the predictive performance of the proposed antenna. The overall size of the antenna is only 44.6×31.8×0.5mm3, and the operation frequency of the antenna ranges from 2.59 GHz to 2.85 GHz (9.5%) based on |S11| ≤ -10 dB, the gain is about 1.98dBi, which are in well agreement with the simulated results.

Compact Co-Linearly Polarized Microstrip Antenna With Fence-Strip Resonator Loading for In-Band Full-Duplex Systems

A compact co-linearly polarized microstrip antenna with identical radiation properties is proposed and validated for in-band full-duplex systems. By exploring a fence-strip resonator (FSR) in the central plane of a patch, good isolation is achieved between the transmitting and receiving ports. The proposed FSR consists of a metallic vias fence and a strip with a distance away from the ground, performing as a pair of distributed inductor and capacitor. When the FSR is resonating, the radiating current is concentrated in the half part of the patch, performing at its half-TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode with high port isolation. To validate the proposed antenna, a prototype with the size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.25\lambda _{0} \times 0.25\lambda _{0} \times 0.04\lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at center frequency) has been fabricated and characterized, with experiments consistent well with simulations. A measured port isolation higher than 20 dB is achieved over the operating bandwidth of 2.40–2.52 GHz with the maximum of 30 dB. The proposed antenna is with the merits of compact size, low profile, simple feed, and planar-integrated structure for in-band full-duplex systems.

A SVPWM Method for Parallel Resonant DC Link Inverter With the Smallest Loss in the Auxiliary Commutation Circuit

In order to reduce the operating frequency and loss of the auxiliary commutation circuit (ACC) and current stress of auxiliary switches of a parallel resonant dc-link inverter (PRDCLI), this article proposes a novel space vector pulsewidth modulation (SVPWM) method. The novel SVPWM method can reduce the number of operations of the ACC to once in every PWM cycle on the premise of realizing soft switching of all switches, thereby reducing the operating frequency and loss of the ACC. At the same time, by adding the shunt dead time, the novel SVPWM method can avoid the superposition of the resonant current and load current, thereby minimizing the current stress of auxiliary switches. In addition, the novel SVPWM method can apply to any PRDCLI with the ability of variable zero voltage durations. Under the novel SVPWM method, according to the equivalent circuits of different operation modes, the operation principle, soft switching realization conditions and parameter design methods of the inverter are analyzed. Finally, a 10-kW/16-kHz prototype is built using insulated gate bipolar transistors to verify the validity of the novel SVPWM method.

Determining potential passive islanding detection indicators for single-point single inverter, single-point multi-inverter and multi-point multi-inverter scenarios

Distributed Generation (DG) sources predominantly renewable energy-based like solar photovoltaic and wind energy sources are considerably penetrated in power system networks. This high penetration of DG sources may lead to the formation of unintentional islands which is hazardous to both the equipment and personnel, if sustained. In this paper, 46 passive parameters are considered to find out which candidate(s) are promising for detecting sustained unintentional islands and avoid false DG trips. These 46 parameters are derived from point of common coupling (PCC) voltage, DG output current, frequency, power factor angle, active and reactive powers. All these parameters are tested on standard IEEE 13 and 34 bus distribution networks integrated with inverter-interfaced DGs at different locations for different penetration levels in MATLAB/SIMULINK environment. The parameters are tested for different islanding events (comprising of various local loads such as conventional parallel RLC resonant load, R, RC, and RL loads) and for different non-islanding events. The parameters are then ranked accordingly by a suitable averaging approach based performance ranking technique. From this analysis, the best candidates are obtained for detecting inverter DG islands at single-point (or single PCC) location and multi-point (or multiple PCCs) locations. Multiple best passive candidates are obtained for different island scenarios from which a set of promising islanding detection indicators are proposed.

Optimization of Bio-Implantable Power Transmission Efficiency Based on Input Impedance

Recently, the inductive coupling link is the most robust method for powering implanted biomedical devices, such as micro-system stimulators, cochlear implants, and retinal implants. This research provides a novel theoretical and mathematical analysis to optimize the inductive coupling link efficiency driven by efficient proposed class-E power amplifiers using high and optimum input impedance. The design of the coupling link is based on two pairs of aligned, single-layer, planar spiral circular coils with a proposed geometric dimension, operating at a resonant frequency of 13.56 MHz. Both transmitter and receiver coils are small in size. Implanted device resistance varies from 200 Ω to 500 Ω with 50 Ω of stepes. When the conventional load resistance of power amplifiers is 50 Ω, the efficiency is 45%; when the optimum resonant load is 41.89 Ω with a coupling coefficient of 0.087, the efficiency increases to 49%. The efficiency optimization is reached by calculating the matching network for the external LC tank of the transmitter coil. The proposed design may be suitable for active implantable devices.

Delay-Sum Group Delay Controller With Low-Loss and Low-Phase Variation

This article presents a group delay controller (GDC) circuit based on the delay-sum method. The proposed circuit can potentially be employed in a self-interference cancellation circuit in full-duplex radio systems. The proposed GDC splits the input signal into two signals with different magnitudes and then combines them in-phase at the output port. Variable group delay can be achieved by changing the power ratio of the two signals. The power dividing ratio (PDR) is changed by employing a variable power divider/combiner (VPD/VPC). The resonant reflective loads substitute for a single varactor diode such that the limited PDR of the VPD/VPC does not degrade the group delay variation range of the GDC. The resonant load can provide infinite PDR by covering open to short susceptance. In addition, asymmetrically connecting the VPD and VPC provides a flatter group delay response. As a result, the delay-sum method enables the proposed GDC to provide low and constant insertion loss while providing low insertion phase variation. The proposed delay sum GDC is demonstrated at 2.5 GHz. The measured insertion loss is only 2.18± 0.28 dB with a continuously controlled relative group delay of 430 ps. Furthermore, the insertion phase variation is only 7.3° at 2.5 GHz, and input/output matchings are maintained for all delay settings.

Vibration Suppression Through Variable Stiffness and Damping Structural Joints

This paper introduces a new semi-active strategy for vibration control of truss and frame structures equipped with variable stiffness and damping joints which consist of a shape memory polymer (SMP) core reinforced by an SMP-aramid composite skin. When the joints are actuated to the transition temperature through thermal actuation, the SMP core transitions from a glassy to a rubbery state through a viscoelastic region, which causes a stiffness reduction and an increase of damping. The mechanic behavior of the joint can be thought of as transitioning from a moment to a pin connection. This way, it is possible to cause a shift of the structure natural frequencies and to increase damping, which is employed to obtain a significant reduction of the dynamic response. This paper comprises two parts: (1) characterization of a variable stiffness and damping material model through experimental testing; (2) numerical simulations of a truss bridge and a four-story frame, which are equipped with variable stiffness and damping joints. The truss bridge (case A) is subjected to a resonance and a moving load while the four-story frame (case B) is subjected to El Centro earthquake loading. For case A under resonance loading, the dynamic response can be reduced exclusively through a frequency shift and ignoring viscoelastic effects. For case A under moving load and case B under earthquake loading, vibration suppression is mostly caused by the increase of damping due to viscoelastic effects. Control time delays due to joint heating have been included in the analysis. When the joints are actuated to the transition range 55°C–65°C, which is specific to the SMP adopted in this study, the acceleration peak amplitude reduces by up to 95% and 87%, for case A and case B, respectively. For both cases, damping increases by up to 2.2% from undamped conditions (25°C). This work has shown that the adoption of variable stiffness and damping structural joints has great potential to enable a new and effective semi-active control strategy to significantly reduce the structure response under a wide range of dynamic loading conditions.

Mixed Inverter Regulation Method for Induction Heating

One of the commonly used methods of voltage source inverter regulation for induction heating is a frequency method of regulating the output power of the inverter, based on the frequency selectivity of the resonance load circuit. With frequency regulation at low values of the Q-factor of the resonance circuit, deep regulation of the output power is impossible. As a result, other methods of regulation are desirable. The article discusses the issue of using a mixed pulse and frequency phase or latitude regulation method under the obligatory conditions of the soft switching mode.

An 8.5-Gb/s/Pin 12-Gb LPDDR5 SDRAM With a Hybrid-Bank Architecture, Low Power, and Speed-Boosting Techniques

An 8.5-Gb/s/pin (Gb/s) 12-Gb LPDDR5 SDRAM is implemented in a second-generation 10-nm DRAM process with a hybrid-bank architecture that provides a power-optimized bank solution depending on the bank modes (4B/4BG, 16B-merged bank, 8B-split bank). Based on the specified bank modes, vertical and horizontal skew-cancel schemes for high density and an RBUS-based DBI ac to minimize data transition are newly proposed. Thus, the switching power of RBUS DBI ac is saved by 8.9% compared to that of DBI ac “OFF.” To improve the rank interleaving efficiency with a current increase, partially enabled WCK (PE-WCK) mode is proposed, which minimizes the number of enabled circuits for maintaining the WCK2CK synchronization. Therefore, the current can be saved by 62% without a timing constraint compared to the WCK always-ON mode. To achieve high-speed operation beyond 6.4 Gb/s, speed-boosting techniques, namely, the two-step duty corrector, active resonant load (ARL), and one-tap decision feedback equalizer (DFE) with offset calibration, are newly adopted. In the coarse step in the two-step duty corrector, the value of the duty error decreases to below 5% by suppressing the dc signal. In the fine step, the remaining duty error is further reduced within 2.5 ps by the duty cycle monitor (DCM) and duty cycle adjustor (DCA). Moreover, the skew increase beyond 6.4 Gb/s due to the bandwidth limit by the heavy loading of four-phase WCK signals is alleviated by the ARL, where the four-phase skew is within 5 ps irrespective of process, voltage, and temperature (PVT) variations. The direct feedback DFE enables fast feedback (<; 118 ps) for tap coefficient control, and offset calibration reduces the three-sigma offset of the four dynamic latches in DQ within 5 mV.

Resonant Frequency and Load Voltage in Voltage-Source Type Wireless Power Transfer Circuits using Series and Parallel Resonant Capacitors

Resonant Frequency and Load Voltage in Voltage-Source Type Wireless Power Transfer Circuits using Series and Parallel Resonant Capacitors

Test strategy for a 25-dBm 1-GHz CMOS power amplifier in a wireless power transfer context

ABSTRACT In this article, we report the test strategy and the results obtained from measurements of a CMOS integrated power amplifier. The power amplifier was designed to optimally-drive an inductive link used in wireless power transfer. As part of the proposed strategy, we designed an integrated oscillator to generate the carrier frequency, as well as dc and ac envelope detectors to estimate the output power and the backscatter response. A printed board based on a microcontroller was designed to implement several test functions in a compact way. The oscillator frequency and the power delivered to the resonant load can be digitally controlled, giving flexibility to the system. Using all the designed circuits we measured the performance of the power amplifier, that achieved a maximum output power of 24.2 dBm with 48.1% efficiency at the 986 MHz frequency.

Monolithic CMOS Microwave Heater With Programmable Thermostat Function for Thermotherapy

A monolithic microwave heater with programmable thermostat function is implemented for thermotherapy. To achieve microwave heating, the heater adopts a 2.4-GHz oscillator to generate the microwave and uses an amplifier with LC resonance load to enhance the signal strength. Consuming the power of 113.0 mW, the amplifier delivers the power of 13.2 dBm. The microwave heater is integrated with temperature sensors, an 11-bit SAR-ADC and a comparator to achieve the programmable thermostat function. For 3-mm thick agar phantoms, the heating rate is around 0.16°C/min. The heater successively achieves the programmed temperature increases of 1.5, 3.0 and 4.5°C, with the standard deviation <; 0.19°C under the thermostat condition.