Input Frequency Research Articles

A Wide Range Duty‐Cycle PWM Generator Using Oxide‐TFTs on a Flexible Substrate

ABSTRACTThis work presents an experimental characterization of a novel clocked regenerative comparator with oxide TFT (a‐IGZO) technology on a flexible substrate. The circuit functionality is demonstrated as a wide range duty‐cycle PWM signal generator with a triangular input signal. The regenerative latch in the comparator is implemented with diode‐load–based inverters. The proposed circuit has shown a linear variation in the duty‐cycle from 12% to 84%, when the reference voltage () is varied from 0.5 to 3.3 V, respectively, in the clocked comparator. Further, a reliable operation is observed up to an input signal frequency of 2 kHz at a supply voltage of 4 V, with a power dissipation of 20 W. This circuit would find potential applications in wearable bio‐medical and neuromorphic computational systems.

Flexible Photoacoustic Device Integrating Electroluminescence, Piezoelectric Vibration, and Pressure Sensing.

Marine organisms rely on the integration of light, sound, and pressure sensing for essential activities such as communication, hunting, and predator evasion. Current bioinspired devices, however, are limited by independent sensing modules, leading to complex designs and reduced adaptability. This study addresses these challenges by developing a multifunctional flexible photoacoustic device (MFPAD) that integrates electroluminescence, piezoelectric vibration, and pressure sensing into a single structure. Using airflow-assisted electrospinning, the device's fibrous layers were fabricated to optimize mechanical properties and enable synchronized responses to luminescence, sound, and pressure. Evaluations showed that MFPAD is highly sensitive to pressure changes, with corresponding light emissions, and efficient sound output modulated by input voltage and frequency. The device also enabled real-time posture tracking in robotic fish using an image recognition algorithm based on luminescence. Additionally, deep learning models allowed for the reconstruction of missing key points during motion. These findings demonstrate the promising potential of MFPAD for advancing bioinspired systems with multimodal sensing capabilities, offering a scalable solution for complex environments.

Observation of biological and emulsion samples by newly developed three-dimensional impedance scanning electron microscopy

Imaging at nanometre-scale resolution is indispensable for many scientific fields such as biology, chemistry, material science and nanotechnology. Scanning electron microscopes (SEM) are widely used as important tools for the nanometre-scale analysis of various samples. However, because of the vacuum inside the SEM, a typical analysis requires fixation of samples, a drying process, and staining with heavy metals. Therefore, there is a need for convenient and minimally invasive methods of observing samples in solution. Recently, we have developed a new type of impedance microscopy, multi-frequency impedance SEM (IP-SEM), which allows nanoscale imaging of various specimens in water with minimal radiation damage. Here, we report a new IP-SEM system equipped with a linear-array terminal, which allows eight tilted images to be observed in a single capture by applying eight frequencies of input signals to each electrode. Furthermore, we developed a three-dimensional (3D) reconstruction method based on the Simulated Annealing (SA) algorithm, which enables us to construct a high-precision 3D model from the 8 tilted images. The method reported here can be easily used for 3D structural analysis of various biological samples, organic materials, and nanoparticles.

Energy-efficient high-linearity SAR ADC with a unary–binary hybrid capacitor switching method

This study developed a 10-bit 10 MS/s energy-efficient and high-linearity successive approximation register (SAR) analog-to-digital converter (ADC). The design utilized a capacitor array structure employing “3-bit thermometer code + 6-bit binary code” to achieve 10-bit quantization through a Vcm-based three-level capacitor switching scheme. The thermometer codes optimized the switching capacitors of the most significant bits to enhance linearity. Further, a unary and binary code control method was implemented to automatically switch across the remaining unary code capacitors when the differential output of the digital-to-analog converter was below 64 least significant bits (LSB). This method reduces the switching energy by 30% compared to the binary CDAC, while RMSDNL and RMSINL are reduced by 47.50% and 26.08%, respectively. The 10-bit SAR ADC was designed with 0.18μm CMOS technology, and the ADC core occupied an area of 0.077 mm2. At supply and reference voltages of 1.2 V, the ADC achieved differential non-linearity and integral non-linearity values of +0.36/−0.32 and +0.4/−0.37 LSB, respectively, at a sampling frequency of 10 MS/s and with a 1% capacitor mismatch. At an input signal frequency of 4.65 MHz, the ADC achieved a signal-to-noise-and-distortion ratio (SNDR) and spurious-free dynamic range (SFDR) of 60.07 and 80.03 dB, respectively. The ADC consumed a power of 137.36 μW, and the Walden figure of merit was 16.74 fJ/conversion-step.

A Novel Direct-Binary Amplitude Modulator Integrated with a 16-Times Frequency Multiplier for 5G+ Applications

This article presents a novel passive direct binary amplitude modulator (AM) integrated with two frequency multipliers (FMs) and a drive amplifier. Both FMs are composed of a harmonic generator and a modified cascode buffer, along with an additional single-to-differential amplifier added in front of the first FM. The input frequency band (1.5–1.75 GHz) is up-converted to the intermediate frequency band of 4–5 GHz by the first FM, while the second FM up-converts the IF band to the target millimeter wave band of 24–28 GHz. Furthermore, the mm-wave amplitude is directly modulated by a capacitor ladder whose ratio is digitally programmable. This unique capacitor-ladder structure AM is employed to attain uniformly distributed constellation points and improve the output signal-to-noise ratio. The proposed modulator is fabricated on a 65-nm CMOS with a die size of 0.73 mm<sup>2</sup>. When applying the modulator to I/Q paths, 1.33% error vector magnitude for 256-QAM was measured at 26 GHz.

Effects of input frequency and microvariation on knowledge of negative inversion in L2 English

Abstract The present study investigates whether L2 learners of English distinguish between (un)grammatical word orders after fronted negative adverbials to identify negative inversion. Previous research on transfer and resetting of verb second (V2) in L1 German–L2 English is extended to explore residual V2 in the form of negative inversion. An acceptability judgment task elicited sentence ratings from advanced German-speaking learners of English for fronted negative adverbials with local and sentential scope. In addition, corpus frequency data of these negative adverbials were related to the learners’ ratings in order to investigate the potential role of input effects. Results suggest that linguistic constraints on microvariation with respect to fronting negative adverbials are broadly in place for learners at this proficiency level, as the scope of fronted negation has an effect on acceptability of negative inversion. Continued significant differences in acceptability judgements of advanced learners compared to native speakers indicate, however, that learners have not completely converged on the target pattern of microvariation. This is related to frequency and reliability of input.

Hybridization of Cockcroft-Walton and Dickson Voltage Multipliers for Maximum Output Through Effective Frequency Dedication in Harvesting Radio Frequency Energy

Objective: This study investigates solutions to the challenges of limited RF energy harvesting by designing a hybridized voltage multiplier system aimed at optimizing output across a wide frequency range. Theoretical Framework: The research centers on the principles and comparative efficiencies of the Cockcroft-Walton and Dickson voltage multipliers, known for their applications in RF energy harvesting. These multipliers’ performance was analyzed theoretically to guide a hybrid design that could adaptively respond to input frequency variations. Method: Voltage multipliers were designed and simulated in Multisim, with further analysis in MATLAB. Both the Cockcroft-Walton and Dickson voltage multipliers were subjected to a constant input of 1V across frequencies from 50 Hz to 5 GHz to assess their respective efficiencies. Subsequently, a hybrid voltage multiplier system was developed, combining an 8-stage Cockcroft-Walton and an 8-stage Dickson multiplier. A fast Fourier transform (FFT) frequency-selective algorithm, implemented in MATLAB, dynamically directed input voltages to the optimal multiplier based on frequency. Results and Discussion: Results showed that the Dickson multiplier excelled in the lower frequency range (50 Hz to 1 MHz), achieving a maximum output of 14.763V at 5 kHz and 10 kHz. In contrast, the Cockcroft-Walton multiplier was more effective in the higher frequency range (1 MHz to 5 GHz), reaching a peak output of 6.671V at 5 GHz. The hybrid system demonstrated efficient, frequency-dependent voltage multiplication and aligned well with anticipated performance metrics, suggesting an improvement in RF energy harvesting across the tested frequency range. Research Implications: This work contributes to the field of RF energy harvesting by introducing a frequency-adaptive system that enhances voltage output through targeted frequency routing. The results underscore the potential for hybrid designs to overcome limitations associated with individual voltage multipliers, presenting a versatile approach to harvesting RF energy effectively across broad frequency spectra. Originality/Value: By implementing a hybrid approach with a frequency-selective algorithm, this study offers an innovative solution for frequency-dependent RF energy harvesting. The findings provide a foundation for future research into adaptable energy harvesting systems that optimize voltage output across diverse frequencies, with practical implications for RF-powered devices and wireless energy transfer applications.

A compliant mechanism actuated bistable hybrid mode triboelectric nanogenerator

Abstract Traditional contact-separation mode triboelectric nanogenerators (CS-TENGs) and lateral sliding mode TENGs exhibit distinct strengths and weaknesses in terms of their charge generation capability and durability. In this study, by leveraging a bistable compliant mechanism (BHM-TENG), we propose a hybrid mode TENG, which synthesizes the features of two traditional working modes to achieve both high durability and satisfactory performance. The proposed design exhibited a 78.6% surge in voltage output and a 142% surge in power density compared to CS-TENG. The design also maintains over 95% power generation capability after 100 000 cycles. Moreover, the compliant bistable mechanism offers a reliable actuation method at low frequencies, validated through experiments supported with a mathematical model. Real-world energy harvesting applications enabled by BHM-TENG are also discussed.

Input / Output Relationships for the Primary Hippocampal Circuit.

The hippocampus is the most studied brain region but little is known about signal throughput -- the simplest, yet most essential of circuit operations -- across its multiple stages from perforant path input to CA1 output. Using hippocampal slices derived from male mice, we have found that single-pulse lateral perforant path (LPP) stimulation produces a two-part CA1 response generated by LPP projections to CA3 ('direct path') and the dentate gyrus ('indirect path'). The latter, indirect path was far more potent in driving CA1 but did so only after a lengthy delay. Rather than operating as expected from the much discussed trisynaptic circuit argument, the indirect path used the massive CA3 recurrent collateral system to trigger a high frequency sequence of fEPSPs and spikes. The latter events promoted reliable signal transfer to CA1 but the mobilization time for the stereotyped, CA3 response resulted in surprisingly slow throughput. The circuit transmitted theta (5Hz) but not gamma (50Hz) frequency input, thus acting as a low-pass filter. It reliably transmitted short bursts of gamma input separated by the period of theta wave - CA1 spiking output under these conditions closely resembled the input signal. In all, the primary hippocampal circuit does not behave as a linear, three-part system but instead uses novel filtering and amplification steps to shape throughput and restrict effective input to select patterns. We suggest that the operations described here constitute a default mode for processing cortical inputs with other types of functions being enabled by projections from outside the extended hippocampus.Significance statement Despite intense interest in hippocampal contributions to behavior, surprisingly little is known about how signals are processed across the network linking cortical input to CA1 output. Here, we describe the first input/output relationship for the system with results challenging the traditional tri-synaptic circuit concept. Signal throughput requires mobilization of recurrent activity within CA3 to amplify sparse input from the dentate gyrus into an unexpectedly stereotyped composite response. Potent low-pass filters determine effective input patterns. These results open the way to new analyses of how variables such as aging affect hippocampus and its contributions to behavior while providing material needed for biologically realistic models of the structure.

Directional control law functional analysis and design for civil aircraft simulator

Abstract Functional analyses of directional flight control law for a typical civil aircraft are conducted, including directional maneuver, rudder limiter, coordinated turn, Yaw Damper, Thrust Asymmetrical Compensation, Gust Alleviation, manual rudder trim, etc. Through inputs of doublet, step input, and sweeping frequency, open loop control characteristics are analyzed based on a linearized state-space matrix. Simulink block architecture of a closed-loop directional control law is constructed, aiming to fulfill flight control functions, including pedal-to-rudder control, Yaw Damper, coordinated turn, and gain-tuned rudder limiter. Simulations for the previously designed closed-loop directional control law are performed to verify the characteristics of directional handling qualities in the aspect of the Yaw Damper, directional static and dynamic stability, maneuverability, and sweeping frequency.

ВЛИЯНИЕ ДИАМЕТРА СЕМЯПРОВОДА НА ПОКАЗАТЕЛИ ВЫСЕВА

To ensure a high performance indicator of the seeders, it is necessary to pay due attention to each element of the equipment used. In order to assess the effect of the diameter of the seed duct on the uniformity of its flight time by corn seeds, laboratory experimental studies were conducted in which corn seeds were passed through nozzles with diameters of 14, 20, 27, and 38 mm. In addition, during the experiment, the frequency of seed entry into the seed duct was changed in the range from 6.5 pcs/s to 23.7 pcs/s and the change in the coefficient of variation of intervals and seeding quality were evaluated. It was found that with an increase in the diameter of the seed duct from 14 to 38 mm, there is a deterioration in the uniformity of its flight time by corn seeds of various fractions. An increase in the air flow velocity helps to improve the uniformity of the flight time of the seed ducts. With a seed input frequency of 6.5 pcs/s, their inversion inside the seed duct is practically absent, the coefficient of variation of seed ejection intervals increases with increasing diameter of the seed duct. An increase in the frequency of seed entry into the seed duct to 23.7 pcs / s leads to a sharp violation of the quality of seed supply by the seed duct with a diameter of 14 mm, up to the absence of inversion of seeds inside. The quality of the seeding machine when using a seed pipe with a diameter of 20 mm is not impaired. The seed line ensures a uniform supply of seeds and ensures a set seeding rate. The uniformity of seeding in this seed duct is higher than in large-diameter seed ducts, and the air consumption is lower. These indicators give reason to recommend seed lines with a diameter of 20 mm for use in pneumatic seed drills for sowing corn.

Age-related increase in the excitability of mouse layer V pyramidal neurons in the primary motor cortex is accompanied by an increased persistent inward current.

Sarcopenia, or pathological age-related loss of muscle strength and mass, contributes to physical function impairment in older adults. While current understanding of sarcopenia is centered mostly on neuromuscular mechanisms, mounting evidence supports that deficits at the level of the primary motor cortex (PMC) play a significant role. Despite the importance of the PMC to initiate movement, understanding of how age affects the excitability of layer V pyramidal neurons (LVPNs) of the PMC is limited. To address this, we used the whole-cell patch clamp technique to measure the excitability of LVPNs of the PMC in young, late adulthood, and old mice. Old LVPNs had increased firing frequency and membrane input resistance, but no differences in action potential kinetics versus young and late adulthood mice. Since changes in the persistent inward current (PIC) are known to contribute to changes in motor neuron excitability, we measured LVPN PICs as a putative contributor to LVPN excitability. The PIC amplitude was increased in old LVPN via increases in Na+ and Ca2+ PICs, in addition to being active across a wider voltage range. Given that LVPN function is integral to initiation of voluntary muscle contraction, altered LVPN excitability likely contributes to age-related impairment of physical function.

Seismic mitigation of porcelain cylindrical electrical equipment using synergistic concept with base isolation and tuned mass damper

Porcelain cylindrical electrical equipment (PCEEs), such as potential and current transformers, are critical components of electrical substations and essential to power supply networks. Nevertheless, previous strong earthquakes have rendered high vulnerability and poor performance of PCEE during seismic occurrences. To improve seismic performance of PCEE and alleviate adverse seismic impacts, an innovative synergistic mitigation method based on base isolation (BI) and tuned mass damper (TMD) was proposed and subsequently employed to PCEE. Combining BI with TMD allows for a greater utilization of each technology’s capabilities while also circumventing some of the limits of each. While TMD effectiveness is sensitive to input ground motion frequencies, BI could act as a filter to tune input frequency and help TMD fulfill better damping effectiveness. TMD could in return help BI achieve better stability under long-period dominant or pulse-like ground motions. The BI-TMD effectiveness and robustness were investigated using finite element modeling and nonlinear time history analysis. A comprehensive parametric study that considers variable PCEE frequencies, BI periods, TMD mass ratios, and TMD control frequencies was conducted. Results show that the proposed BI-TMD method can significantly enhance the effectiveness and robustness beyond BI single control in mitigating seismic responses of PCEE.

The influence of pragmatic function on children's comprehension of complex because- and if-sentences

IntroductionIn complex adverbial sentences, the connectives because and if can perform different pragmatic functions (e.g. Content, Speech-Act), although this is often overlooked in studies investigating children's acquisition of these connectives. In this study, we investigated whether pragmatic variation is responsible for some of the difficulty young children have in understanding because- and if-sentences and tested the extent to which patterns of acquisition are related to the cognitive complexity or input frequency of the different pragmatic types.MethodsNinety-two children (aged 3–5; F = 39) and 20 adults (F = 12) took part in a forced-choice picture task where they had to identify correct pictures after hearing Content and Speech-Act because- and if-sentences.ResultsResults showed that children were most accurate on the sentence type where cognitive simplicity and input frequency converge (If Content), but this pattern was largely driven by the girls in the study. For response times, children were fastest with the least cognitively complex sentence types. However, for because Speech-Act sentences, there was an inverse relationship between response time and input frequency.DiscussionTaken together, these findings suggest that neither account (cognitive complexity or input frequency) can fully explain the findings. Instead, we suggest that the relative contributions of both factors are best understood in terms of the relevance of these utterances to children and the precise contexts in which children hear these utterances produced.

Effects of Input Frequency Distribution on L2 Acquisition of Chinese Contraction Constructions

Effects of Input Frequency Distribution on L2 Acquisition of Chinese Contraction Constructions

Effect of the method of excitation of the plasma antenna on the spectral characteristics of the radiated signal

The radiation of signal by the plasma asymmetrical vibrator antenna is studied for two methods of its excitation. Earlier, it was shown that the 2nd and 3rd harmonics of the input signal frequency in the radiation spectrum of the plasma antenna are 10—20 dB stronger than those of a metal antenna with the same geometry. In this work, we study experimentally and by computer simulations the effect of the method of excitation of the plasma asymmetrical vibrator antenna on the spectral characteristics of the signal that it radiates. For the two excitation methods of the antenna, through an electrode and through a coaxial coupler, it was shown that the strength of the signal components at the frequency of the radiated signal and its multiple harmonics is different. The introduction of the coaxial coupler in the antenna excitation scheme allowed us to improve the coupling at the input signal frequency and decrease its components at the 2nd and 3rd harmonics. For the plasma antenna with the coaxial coupler, the difference between the 1st and 2nd harmonics was increased by almost 6 dB, and between the 1st and the 3rd ones by almost 20 dB compared to the antenna excitation scheme through the electrode.

Modulation of Phase-Locking Characteristics of NbOx Memristor by Ag Doping.

Memristors based on niobium oxide have attracted wide interest due to their applications in artificial neural network. Phase-locking (PL) characteristics of NbOx newly explored roots in complex nonlinear dynamics and exhibits great potential in periodical signal handling because of its bioinspired nature. In this study, we fabricate a Pd/Nb/Ag-NbOx/Nb/Pd memristive structure and study the effects of Ag doping on the PL characteristics. We clearly see that the NbOx memristor responds to signal in three distinct patterns. For the low-frequency input, the memristor fires spike series and locks the phase near during the positive period of sinusoidal input, and it encodes the input features by the spike number per period. For the middle-frequency input, the memristor fires one spike per period at a definite phase. The output has the same frequency as the input. The locked phase is proportional to the input frequency. For the high-frequency input, the memristor transforms high frequency to low frequency signal and locks at a definite phase higher than 2π. We combined the microstructural analysis and chaos dynamics to know that Ag doping will lower the activation energy, enhance the responding rate, and enhance thermal conductivity, which extends the locked frequency to 1.7 times the value of the undoped NbOx memristor. We also obtained the locked frequency of even 40 MHz after modulating the elementary circuit configuration according to the material modification and chaos model. Our study proposes to handle a signal with high efficiency resembling auditory sense and inspires a novel artificial intelligent computation prototype.

Catalytic Degradation of Bisphenol A in Water by Non-Thermal Plasma Coupled with Persulfate

Bisphenol A (BPA) has become prevalent in the environment due to its extensive use in industrial materials, thus raising significant concerns regarding its potential toxicity and health effects. In this study, an efficient and eco-friendly non-thermal plasma (NTP) was used to catalyze persulfate (PS) for BPA decomposition, and the results showed that the integrated system could effectively degrade BPA. The best performance was attained at a PS to BPA mass ratio of 5:1, with a degradation rate of 91.3% following a 30 min treatment. The degradation rate of BPA increased with increasing input voltage and frequency; conversely, it decreased with an increase in BPA’s initial concentration. Higher BPA degradation rates could be achieved in alkaline environments. Radical quenching experiments revealed that SO4−•, OH•, O2−• and 1O2 were important active substances involved in BPA degradation. Nine intermediate products were identified by liquid chromatography–mass spectrometry (LC-MS), and four degradation pathways were deduced. Additionally, a toxicity analysis of intermediate products was performed. The significant decrease in chemical oxygen demand (COD) during the actual wastewater treatment suggested that the NTP/PS system has good applicability in actual wastewater treatment.

Multi-task photonic reservoir computing: wavelength division multiplexing for parallel computing with a silicon microring resonator

Nowadays, as the ever-increasing demand for more powerful computing resources continues, alternative advanced computing paradigms are under extensive investigation. Significant effort has been made to deviate from conventional Von Neumann architectures. In-memory computing has emerged in the field of electronics as a possible solution to the infamous bottleneck between memory and computing processors, which reduces the effective throughput of data. In photonics, novel schemes attempt to collocate the computing processor and memory in a single device. Photonics offers the flexibility of multiplexing streams of data not only spatially and in time, but also in frequency or, equivalently, in wavelength, which makes it highly suitable for parallel computing. Here, we numerically show the use of time and wavelength division multiplexing (WDM) to solve four independent tasks at the same time in a single photonic chip, serving as a proof of concept for our proposal. The system is a time-delay reservoir computing (TDRC) based on a microring resonator (MRR). The addressed tasks cover different applications: Time-series prediction, waveform signal classification, wireless channel equalization, and radar signal prediction. The system is also tested for simultaneous computing of up to 10 instances of the same task, exhibiting excellent performance. The footprint of the system is reduced by using time-division multiplexing of the nodes that act as the neurons of the studied neural network scheme. WDM is used for the parallelization of wavelength channels, each addressing a single task. By adjusting the input power and frequency of each optical channel, we can achieve levels of performance for each of the tasks that are comparable to those quoted in state-of-the-art reports focusing on single-task operation. We also quantify the memory capacity and nonlinearity of each parallelized RC and relate these properties to the performance of each task. Finally, we provide insight into the impact of the feedback mechanism on the performance of the system.

An Inductor‐Less Zero‐IF Down‐Conversion Mixer With Low Flicker Noise and High Conversion Gain

ABSTRACTThis paper presents a novel active inductor (AI) to improve the performance of a down‐conversion active mixer in terms of conversion gain (CG) and flicker noise. The proposed AI exhibits negative resistance and partially flat inductance over a wide frequency band of 0.5–4.5 GHz. The effect of inserting the AI between the source of the switching quad of a Gilbert cell mixer is theoretically analyzed. The proposed inductor‐less mixer, designed to operate at a 2.4‐GHz RF input frequency and a 10‐MHz IF output frequency, employs current reuse and self‐forward body bias (SFBB) techniques. The proposed circuit is simulated in Cadence Spectre‐RF using RF‐TSMC 0.18‐μm CMOS technology. Post‐layout simulations demonstrate that the proposed AI significantly reduces flicker noise by over 23 dB at an IF output frequency of 1 kHz and improves the CG by over 16 dB at an RF frequency of 2.4 GHz. The proposed mixer achieves a CG of 37.6 dB and a flicker noise corner frequency of 6 kHz. Additionally, it exhibits a third‐order intermodulation intercept point (IIP3) of −5.2 dBm and a double‐sideband noise figure (DSB‐NF) of 6.1 dB at the IF output frequency of 10 MHz. Operating with a 1.5‐V supply, the proposed mixer consumes 10.6 mW of power.