Sine Wave Input Research Articles

Effect of nonlinearity induced by atomic switch in Ag/Ag2S nanoparticles on performance of in-materio reservoir computing

A random network of Ag/Ag2S nanoparticles (NPs) was used as a physical system in reservoir computing (RC) because the network has nonlinear and dynamical characteristics. Ag/Ag2S NPs were synthesized by the modified Brust–Schiffrin method. Atomic switching among the NPs caused nonlinear dynamical behavior of the random network. The Fourier transform of output signals indicated that the generated harmonics were far higher with a larger amplitude of the input sine wave because the atomic switching occurred only at high bias voltages. Higher accuracy was achieved in the Boolean logic RC task because of the nonlinearity originating from switching. These findings suggest that nonlinearity plays a fundamental role in the design and implementation of RC devices.

Auditory inputs modulate intrinsic neuronal timescales during sleep

Functional magnetic resonance imaging (fMRI) studies have demonstrated that intrinsic neuronal timescales (INT) undergo modulation by external stimulation during consciousness. It remains unclear if INT keep the ability for significant stimulus-induced modulation during primary unconscious states, such as sleep. This fMRI analysis addresses this question via a dataset that comprises an awake resting-state plus rest and stimulus states during sleep. We analyzed INT measured via temporal autocorrelation supported by median frequency (MF) in the frequency-domain. Our results were replicated using a biophysical model. There were two main findings: (1) INT prolonged while MF decreased from the awake resting-state to the N2 resting-state, and (2) INT shortened while MF increased during the auditory stimulus in sleep. The biophysical model supported these results by demonstrating prolonged INT in slowed neuronal populations that simulate the sleep resting-state compared to an awake state. Conversely, under sine wave input simulating the stimulus state during sleep, the model’s regions yielded shortened INT that returned to the awake resting-state level. Our results highlight that INT preserve reactivity to stimuli in states of unconsciousness like sleep, enhancing our understanding of unconscious brain dynamics and their reactivity to stimuli.

Active power measurement uncertainty modelling and propagation analysis in case of harmonically distorted signals

The harmonic distortion of electrical waveforms results in a need for instruments’ performance evaluation in non-sinusoidal conditions. Specifications, which are valid for sine-wave input signals, are not supposed to be applied directly for uncertainty determination in case of harmonics, due to the non-linear dependence between the measured quantities and the single harmonic components’ magnitudes and phase shifts. Uncertainty calculation is especially challenging in case of power and/or energy measurements, because the corresponding instruments are used for legal metrology purposes i.e. in the regulated trade of electrical energy. The starting point for the concrete evaluation is related to determination of influence factors, which affect the recording of single harmonics’ magnitudes and phase shifts. For overall power and/or energy uncertainty calculation, mathematical modelling, based on analytical relations between single harmonic components and the measured quantity, will be performed. A GUM based perspective for uniting single influence factors is implemented and a simplified approach for the correlation coefficients calculation is adopted. The validation of the model, as well as, the uncertainty propagation analysis due to single harmonic components alteration, is backed up by real time measurements, conducted with high accuracy class measurement equipment.

Prototype of a digitizer module based on multicycle-encoding FPGA ADC for a small animal PET

Current research in small animal positron emission tomography (PET) scanners focus on obtaining better spatial resolution and higher sensitivity. These enhancements of scanner performance result in a corresponding increase in the complexity of the electronics, which usually manifests through an increase in the number of electronics channels. Analog-to-digital converters (ADCs) implemented in field programmable gate arrays (FPGAs) are an effective way to simplify electronics complexity. In this paper, a resource-saving multicycle-encoding structure of an FPGA-based ADC with automated calibration is proposed, which achieves a sampling rate of 250 Msps. A digitizer module prototype containing 64 charge measurement channels based on the FPGA ADC is designed using a Kintex-7 FPGA. The effective number of bits (ENOB) achieved using the FPGA ADC is 4.26 bits under a 10.0555 MHz sine wave input. The charge measurement resolution of each channel is better than 5‰ full width half maximum under a 0.8 V signal input and 3% under inputs in the range 0.1 V to 1.2 V. The integral nonlinearity of each channel is within ± 1%.

Stability Analysis of 3D UAV Gimbal using Flexible Body

Unmanned aerial vehicle (UAV) application in visual object tracking requires a gimbal to stabilize the camera in following the object’s movement. External disturbance and gimbal stability are the issues in this application. This study aims to analyze disturbance effects and study the stress and modal analysis on UAV gimbal using flexible body concepts. The three-dimensional (3D) gimbal is modeled using the RecurDyn software consisting of 3 arms and a camera. Each of the arms is connected using a revolute joint and a rotational force to represent a motor. The considered disturbances are step, pulse, ramp, and sine wave input. The PID controller is used to stabilize the gimbal arm from the gravity of the camera and external disturbance. The result shows that the PID controller is robust to step, pulse, and ramp disturbance, but not to the sin wave disturbance. In addition, the second arm of the gimbal is the most stressed component and is prone to vibration.

0.3-V Voltage-Mode Versatile First-Order Analog Filter Using Multiple-Input DDTAs.

This paper presents a versatile first-order analog filter using differential difference transconductance amplifiers (DDTAs). The DDTA employs the bulk-driven (BD) multiple-input MOS transistors technique (MI-MOST) operating in the subthreshold region. This results in low-voltage and low-power operational capability. Therefore, the DDTA, designed using 130 nm CMOS technology from UMC in the Cadence environment, operates with 0.3 V and consumes 357.4 nW. Unlike previous works, the proposed versatile first-order analog filter provides first-order transfer functions of low-pass, high-pass, and all-pass filters within a single topology. The non-inverting, inverting, and voltage gain of the transfer functions are available for all filters. Furthermore, the proposed structure provides high-input and low-output impedance, which is required for voltage-mode circuits. The pole frequency and voltage gain of the filters can be electronically controlled. The total harmonic distortion of the low-pass filter was calculated as -39.97 dB with an applied sine wave input signal of 50 mVpp@ 50 Hz. The proposed filter has been used to realize a quadrature oscillator to confirm the advantages of the new structure.

Performance improvement of in-materio reservoir computing by noise injection

Computation performance of in-materio reservoir device was evaluated by varying intensity of noise injection. Materials for the reservoir device was synthesized using a α-Fe2O3/titanium bismuth oxide composite by using the sol–gel method. The prepared samples were characterized by conducting X-ray diffractmetry, transmission electron microscopy, and energy dispersive X-ray spectroscopy to confirm presence of α-Fe2O3, TiO2, and Bi4Ti3O12 nanoparticles. The I–V and V–t curves show nonlinearity, and phase differences between input and output signals, and the fast Fourier transform of the V–t curve showed high harmonics at the input sine wave with 11 Hz of frequency. In the waveform prediction task, the prediction accuracy was improved only when a small intensity of white noise voltage was superimposed to the input information signal.

Shaking Table Test of the Negative Skin Friction of a Single Pile Induced by Seismic Settlement of Model Soft Soil

The negative skin friction (NSF) of pile foundations is one of the most important factors in triggering building subsidence. To study the mechanism and development of the NSF over time, four methods have been used: theoretical calculations, field tests, model tests, and numerical modeling. To address the difficulty of sampling prototype soft soils in model tests, this study uses a dynamic triaxial instrument to select a similar material ratio that can effectively simulate the dynamic properties of the prototype soft soil as a soft soil layer, and input sine waves with different frequencies and peak ground acceleration (PGA) for shaking table tests to investigate the effects of frequency and PGA on the development of the distribution of NSF and the location of the neutral point of the pile foundation. The test results show that the pile NSF is mainly distributed in the upper part of the pile under horizontal sine wave loading, increases rapidly from 0 to 5 s, and stabilizes after 5 s. Its magnitude is influenced by the sine wave frequency and PGA, and the effect of PGA on the NSF is more significant. In addition, the pile neutral point position shifts downwards with increasing sine wave frequency and PGA, but the downwards shift is not significant.

Efficiency Analysis and Design Considerations of a Hysteretic Current Controlled Parallel Hybrid Envelope Tracking Power Supply

This paper presents the realization of an Envelope Tracking Power Supply (ETPS), for a sinusoidal envelope input signal. A parallel hybrid topology is chosen for the implementation. In this topology, a voltage-controlled Class-AB linear amplifier stage and a current-controlled switching converter stage operate in parallel. A hysteretic current control scheme is employed to control the operation of the switching converter. Block-level implementation of the ETPS is done using Simulink 2017b, continuous mode simulation. Simulations are performed using a sinewave input envelope signal = 1.94+ 1.2 sin(ω∙t). The input frequency varied from 1MHz to 60MHz. As the input frequency is increased, the ETPS moves from the linear to the non-linear region of operation. During the transition, the slew rates of the load current and the switching current match at a particular input frequency of 2MHz while the efficiency peaks. The maximum obtained efficiency while tracking the sinewave input signal is 82.3%. The way the efficiency can be optimized by focusing on the matching of the slew rates of load and switching currents is explained. Also, an insight into the study of various circuit parameters and the trade-offs that the designer needs to consider while designing an ETPS, is provided.

Drain-bias dependence of low-frequency Y22 signals for Fe-related GaN traps in GaN HEMTs with different Fe doping concentrations

The bias dependence of trap properties for GaN HEMTs with Fe-doped GaN layers was investigated using low-frequency Y-parameters measurement in the two-port network. This measurement technique can be estimated quasi-equilibrium trap properties and location by changing the combination between gate/drain current response and gate/drain input voltage with small AC signal overlapped fixed DC bias. We focused on Y22 which can be detected only in GaN traps. Activation energies for the GaN traps were estimated bias-by-bias for wide drain voltage (VDS) ranging from 2 V below the knee voltage to 15 V for the saturation region with high current at the gate voltage of 0 V (on-state condition). Fe-related GaN traps with low-frequency Y22 characteristics were identified experimentally using GaN HEMTs including GaN layers with different Fe doping concentrations. The Fe-related GaN trap signals in the imaginary part of Y22 (Im(Y22)) appeared at a peak near 200 Hz at a low VDS of 3 V under on-state conditions and moved to a higher frequency with an increase of VDS. The amplitudes of the trap peaks enhanced around VDS of 3 V. The maximum value in the amplitude of the trap peaks was large for the high-concentration Fe doping. On the other hand, the peak frequency depending on VDS had a similar trend for both the low- and high-concentration Fe doping. The activation energy for the Fe-related trap decreased for VDS up to 7 V and saturated for both Fe doping concentrations. Device simulation was performed to analyze the location in GaN HEMTs for GaN trap response and bias dependence of the activation energy. To simulate the characteristics of Im(Y22), drain current (ID) responses against AC (sine wave) input signal of VDS were calculated at the frequency corresponding to the trap peak. Because ID led VDS in phase, the trap effect is considered to change the trapped charge. From two-dimensional plots for the difference in ionized trap density, trap response regions were located under the gate edge at the drain side. Because the imaginary part of the admittance vector between ID and VDS corresponded with Im(Y22), the Fe-related traps under the gate of the drain side changed the charge condition according to the AC signal and generated the peak in Im(Y22) depending on the frequency. Furthermore, the saturation of the activation energy in the bias-dependence characteristics occurred due to decreasing the thermal conductivity at high temperatures. The temperature in GaN HEMTs at high VDS became high because of the self-heating effect in addition to the high ambient temperature. The internal temperature increase induced the trap peak frequency increase, and the activation energies were saturated.

Novel thin polymeric magnetic membranes study for applications in the future biomedical devices

Biomedical devices such as pumping/mixing fluids, cell-culturing, and drug delivery often use different actuation methods. Magnetic actuation using magnetic particles that are embedded in thin flexible polymeric sheets (membranes) is convenient to use, especially for medical implantable devices such as micropumps, due to the fact they do not require board batteries and exhibit better performances than other actuation methods. The fabrication process of these membranes uses a random distribution of particles. In this work, membranes with a local distribution of magnetic particles are investigated and compared to membranes with randomly distributed magnetic particles, which in turn may enhance the actuation performance for certain applications. Iron oxide particles are embedded into polydimethylsiloxane, and micromagnets are used to localize the position of the magnetic particles within the polymeric mixture during the fabrication process. Three different concentrations are investigated: low (7.5 w/v%), medium (10 w/v%), and high (12.5 w/v%). Static and dynamic measurements of membrane’s maximum deflection values are compared for both types of membranes with a random and a local distribution of magnetic particles. The maximum deflection location is shifted due to the presence of the localized magnetic field for a membrane with a local distribution of magnetic particles. From the experimental results, it is evident that the deflection performance result is much higher for the local distribution of the magnetic particles’ membrane during a static magnetic load and slightly lower during a dynamic (sinewave input) magnetic load at frequencies of 1 and 5 Hz.

Evaluation of Liquefaction Properties of East Coast Sand of New Zealand Mixed with Varied Kaolinite Contents Using the Dynamically Induced Porewater Pressure Characteristics

In earthquake geotechnical engineering, physical model experiments have proven to be significant and valuable in understanding the complex physics and engineering behaviors of prototype undrained soils in fields. An executed literature review indicated that large-scale physical model testing, such as shaking table (ST) and centrifuge devices, have associated advantages and limitations. The current paper presents the design, fabrication, and calibration of a 600N-capacity, small-scale, one-directional (1-D) laboratory ST device that enables quick and valuable assessment of soil liquefaction mechanisms. The dynamically induced porewater pressure (PWP) generation characteristics of sand soil mixed with different percentage weights of clay were evaluated and illustrated as a case study for testing the ST device’s performance. The east coast sand (ECS) of New Zealand’s North Island was mixed with different percentages of kaolinite clay to produce five variants of ECS (00, 05, 10, 20, 25, and 30). Three input sine wave ground motions of a constant frequency of 10 Hz and amplitudes of 2, 3, and 4 were applied and classified in the current study as low, intermediate, and moderate ground motions, respectively, to evaluate the evolution of the dynamic excess pore pressures in the soil samples. The results indicated that the clean ECS and mixed samples with lower clay content (ECS00, ECS05, ECS10, and ECS15) produced the highest excess PWP throughout the three shaking cycles, with higher tendencies of contraction and liquefaction properties. On the other hand, soil samples with a higher percentage of clay (ECS20 and ECS20) yielded the lowest PWP, with softening and dilative properties.

A time-interleaved ADC calibration technique for spectrum monitoring applications

A fully background estimation and calibration technique to reduce the spur powers caused by time-interleaved ADC architecture is presented. The estimations of mismatches are succeeded using easily generated calibration signals. The implementation details for the mismatch estimations and calibrations are provided using a 2.8 GSPS ADC and a FPGA device. Continuous operation of the spectrum monitoring applications is allowed while the mismatch estimation and the calibration process in progress. The offset mismatch calibration is realized using an adder circuit at the background and more than 10 dB spur power reduction is obtained from the proposed method. A digital multiplier circuit is used to realize the gain calibration. The timing skew calibration is fulfilled by the addition of a small offset to the DDS (Direct Digital Synthesizer) phase offset of DDC (Digital Down Converter). It is possible to get more than 6 dB power reduction at some critical spur signals after the application of proposed timing mismatch calibration technique when a single tone sine wave input is applied.

Linear and nonlinear response for radiative heat transfer in many-body systems

A theory of temperature dynamics in many-body systems driven by time-dependent external sources is introduced. The formalism based on the combination of the perturbation theory and the fluctuational-electrodynamics approach in many-body systems. By using response theory, explicit formula for the temperature and phase shifts is derived and expressed in terms of the amplitude and phase of external power sources. Although the proposed method is highly efficient because it can skip the transient response, it is valid when external powers are weak. As an illustration of this theoretical framework, we have shown the dynamics of temperatures in one, two, and three degree of freedom systems driven by sine wave input powers. Finally, we highlighted some emergent phenomena arising from purely dynamical many-body effects, including amplification, attenuation, delaying or accelerating temperature responses. This work could find important applications in the domain of dynamical thermal management at the nanoscale.

A Low Power Sigma-Delta Modulator with Hybrid Architecture.

Analogue-to-digital converters (ADC) using oversampling technology and the Σ-∆ modulation mechanism are widely applied in digital audio systems. This paper presents an audio modulator with high accuracy and low power consumption by using a discrete second-order feedforward structure. A 5-bit successive approximation register (SAR) quantizer is integrated into the chip, which reduces the number of comparators and the power consumption of the quantizer compared with flash ADC-type quantizers. An analogue passive adder is used to sum the input signals and it is embedded in a SAR ADC composed of a capacitor array and a dynamic comparator which has no static power consumption. To validate the design concept, the designed modulator is developed in a 180 nm CMOS process. The peak signal to noise distortion ratio (SNDR) is calculated as 106 dB and the total power consumption of the chip is recorded as 3.654 mW at the chip supply voltage of 1.8 V. The input sine wave of 0 to 25 kHz is sampled at a sampling frequency of 3.2 Ms/s. Moreover, the results achieve a 16-bit effective number of bits (ENOB) when the amplitude of the input signal is varied between 0.15 and 1.65 V. By comparing with other modulators which were realized by a 180 nm CMOS process, the proposed architecture outperforms with lower power consumption.

Design of prototype Front-End Electronics for the Gamma-Gamma collider

The Gamma-Gamma collider is a scientific facility proposed in China to observe two unique interactions at the center-of-mass energy of 1–2 MeV, namely γγ scattering and electron-positron pairs. In the experiment, two γ beams generated by the Compton back-scattering of high-energy electron beams (∼200 MeV) and high-intensity laser beams will collide at the interaction point, and the products will be collected by CsI(Na) crystals and plastic scintillators, and then converted into electric signals by silicon photomultiplier (SiPM) detectors. In this paper, a prototype Front-End Electronics (FEE) is implemented to verify the design requirements concerning the noise level (no more than 3 mV), high sampling rate (1 GS/s) and low power consumption. The prototype FEE comprised 8 differential drivers, 2 low-power switch capacitor array (SCA) DRS4 chips, and an 8-channel Analog-to-Digital Converter (ADC). The input signals were first stored in DRS4 chips for time stretching, then digitized by the ADC, and finally sent to back-end electronics via an optical link. The noise (RMS) of each readout channel on the prototype FEE was less than 3 mV after offset correction, and the ENOB of the channels was better than 6.7 bit when the frequency of input sine waves was less than 70 MHz and the sampling rate of the DRS4 was 1 GS/s. Therefore, the performance of the prototype FEE meets the requirements of the Gamma-Gamma collider.

Design and implementation of higher order sigma delta modulator circuits using FPAA

In this paper, the prototyping of 3rd order, 4th order, 5th order, and 6th order sigma-delta analog to digital converters (Σ∆ ADCs) has been presented. It summarily portrays the method implemented for configuration and reconfiguration of the proposed circuits by using Field Programmable Analog Array (FPAA). Their function was determined in the time domain at a constant 1 V supply voltages which is a sinewave input signal of 20 kHz frequency. The sampling frequency is fs = 4 MHz and the Oversampling ratio is OSR = 50 which yields a bandwidth of 40 kHz. Practical experimentation of the circuits was carried out using the AN221E04 FPAA device from Anadigm. Circuit realization of 3rd order, 4th order, 5th order, and 6th order sigma-delta analog to digital converters (Σ∆ ADCs) using FPAA are shown in figures. Also, sinusoidal input and output waveforms of implemented architectures are shown. A comparison of the proposed designed circuits with the various sigma-delta modulators published in the previous paper is also shown. The proposed sigma-delta modulators can be applied in the investigation and practical study of designing programmable analog devices and systems based on FPAA.

Hydrological signatures describing the translation of climate seasonality into streamflow seasonality

Abstract. Seasonality is ubiquitous in nature, and it is closely linked to water quality, ecology, hydrological extremes, and water resources management. Hydrological signatures aim at extracting information about certain aspects of hydrological behaviour. Commonly used seasonal hydro-climatological signatures consider climate or streamflow seasonality, but they do not consider how climate seasonality translates into streamflow seasonality. In order to analyse the translation of seasonal climate input (precipitation minus potential evapotranspiration) into seasonal catchment output (streamflow), we represent the two time series by their seasonal (annual) Fourier mode, i.e. by sine waves. A catchment alters the input sine wave by reducing its amplitude and by shifting its phase. We propose to use these quantities, the amplitude ratio and the phase shift, as seasonal hydrological signatures. We present analytical solutions describing the response of linear reservoirs to periodic forcing to interpret the seasonal signatures in terms of configurations of linear reservoirs. Using data from the UK and the US, we show that the seasonal signatures exhibit hydrologically interpretable patterns and that they are a function of both climate and catchment attributes. Wet, rather impermeable catchments hardly attenuate the seasonal climate input. Drier catchments, especially if underlain by a productive aquifer, strongly attenuate the input sine wave leading to phase shifts up to several months. As an example application, we test whether two commonly used hydrological models (Identification of unit Hydrographs and Component flows from Rainfall, Evaporation and Streamflow – IHACRES; modèle du Génie Rural à 4 paramètres Journalier – GR4J) can reproduce the observed ranges of seasonal signatures in the UK. The results show that the seasonal signatures have the potential to be useful for catchment classification, predictions in ungauged catchments, and model building and evaluation. The use of potential evapotranspiration in the input restricts the applicability of the signatures to energy-limited (humid) catchments.

A comparison of test manoeuvres for determining rearward amplification of articulated heavy vehicles

Rearward amplification (RA) is an effective indicator of lateral stability for multi-trailer articulated heavy vehicles (MTAHVs). The International Organization for Standardization released the test manoeuvres, ISO-14791, for determining the indicator for MTAHVs. ISO-14791 recommends three methods, including two time-domain and one frequency-domain, to derive the RA measures. It was reported that the results from the three methods were not in good agreement. To explore this inconsistency among these methods, a multiple cycle sine-wave steering input (MCSSI) manoeuvre was simulated to obtain steady-state responses of MTAHVs. Furthermore, an automated frequency response method (AFRM) was used to derive the measures in the frequency-domain. This paper presents simulation results based on an A-Train Double. Results demonstrate that the steady-state RA measures under a MCSSI manoeuvre are in excellent agreement with those from frequency-domain methods. It is revealed that driver's steering behaviours impose a non-negligible impact on the transient RA measures of MTAHVs.

A comparison of test manoeuvres for determining rearward amplification of articulated heavy vehicles

Rearward amplification (RA) is an effective indicator of lateral stability for multi-trailer articulated heavy vehicles (MTAHVs). The International Organization for Standardization released the test manoeuvres, ISO-14791, for determining the indicator for MTAHVs. ISO-14791 recommends three methods, including two time-domain and one frequency-domain, to derive the RA measures. It was reported that the results from the three methods were not in good agreement. To explore this inconsistency among these methods, a multiple cycle sine-wave steering input (MCSSI) manoeuvre was simulated to obtain steady-state responses of MTAHVs. Furthermore, an automated frequency response method (AFRM) was used to derive the measures in the frequency-domain. This paper presents simulation results based on an A-Train Double. Results demonstrate that the steady-state RA measures under a MCSSI manoeuvre are in excellent agreement with those from frequency-domain methods. It is revealed that driver's steering behaviours impose a non-negligible impact on the transient RA measures of MTAHVs.