Input Frequency Research Articles

Study on dynamic post-buckling stability of fast reactor vessels subjected to vertical vibration

Abstract As a lesson learned from the Fukushima nuclear accident, the importance of accident mitigation for Beyond Design Basis Events (BDBEs) is recognized. Excessive earthquake is a typical BDBE. During such events, the Fast Reactor Vessel (FRV) is vulnerable to buckling. The safety goal of FRV under excessive earthquake is to achieve a stable post-buckling state. Our previous study on bending buckling confirmed a global response stability under horizontal vibration. As a parallel study, this paper focuses on axial compression buckling under vertical vibration. Shaking table experiments using thin-walled cylindrical models (R/t=260) are carried out. Similar methodology is applied to investigate the buckling and post-buckling behavior. It is found that axial compression buckling shares an extensive similarity with bending buckling in both buckling mode and post-buckling behavior. Similar global response stability is confirmed due to phase-inverse phenomenon. After buckling, buckling failure becomes stable and does not progress further even when an intense input amplitude is continuously applied. The vibrational load acts as a displacement-controlled load in the out-of-phase domain such that immediate collapse is prevented. Most input energy is dissipated in hysteresis loops rather than being carried by the mass. These mechanisms are independent of input waveform and can be applied to an arbitrary seismic input. In addition, a conservative limit displacement for global response stability is identified. Moreover, the effect of the input frequency ratio, the initial geometrical imperfection and the gravitational force on the post-buckling behavior are clarified.

Lexical frequency and target language input in the primary languages classroom

ABSTRACT This paper presents an exploratory study of L2 input in the primary languages classroom. Teacher talk in 33 videorecorded lessons taught to Year 3 French beginners by a specialist teacher of French was analysed, in order to document the extent and nature of L2 vocabulary input. Further analyses compared the lexis of teacher talk in this primary setting with high-frequency wordlists derived from two reference corpora designed to support the teaching of L2 French. Results showed that children were exposed to c 45,000 words (tokens) of French, reflecting a teacher vocabulary of c 650 lemmas. Intentionally taught lexis such as foods or animal names typically received massed practice, not always supplemented by distributed practice. The teachers’ partial but consistent use of French for classroom management contributed to a well-balanced distribution of word classes. There was considerable overlap with both reference wordlists, and divergence could largely be explained by the teacher’s choice of topics, and incidental use of French to personalise and engage childrens’ individual interests, as well as for classroom management purposes. In discussion, the need for careful planning and management of vocabulary instruction is highlighted, as well as the significant potential of L2 classroom management to enrich lexical input.

Input, Universals, and Transfer in Developing Rhotics: A Sketch in Bilingualism

Understanding the role of input in bilingual phonological acquisition is revealing for deciphering the workings of language acquisition processes. Input and usage distributional frequencies guide and differentiate speech sound acquisition patterns cross-linguistically. Such processes are operant in first- and second-language acquisition. There is an under-representation of investigations on how context-specific input in bilingualism influences the early acquisition of rhotics in child developmental speech longitudinally. This study addresses the gap by tracing a Greek/English bilingual girl’s rhotic development between ages 2;7 and 3;11, utilizing naturalistic data during daily interactions with an adult interlocutor. The study reports and schematically illustrates the child’s bilingual usage frequencies, informing language choice in her production variables, which demonstrate, quantitatively and qualitatively, the effects of context-specific input on rhotic accuracy levels and substitution patterns in both languages. Specifically, distributional frequencies in the input govern the child’s phonemic and phonetic tendencies in the languages. Findings are compared with previous reports in the literature and enhance language acquisition theory, revealing the pivotal role of input in the dynamic interplay with developmental universals, language-specific tendencies, transfer, and individual variation.

Real-Time Reconfigurable Radio Frequency Arbitrary-Waveform Generation via Temporal Pulse Shaping with a DPMZM and Multi-Tone Inputs

Benefitting from a large bandwidth and compact configuration, a time-domain pulse-shaping (TPS) system provides possibilities for generating broadband radio frequency (RF) arbitrary waveforms based on the Fourier transform relationship between the input–output waveform pair. However, limited by the relatively low sampling rate and bit resolution of an electronic arbitrary-waveform generator (EAWG), the diversity and fidelity of the output waveform as well as its reconfiguration rate are constrained. To remove the EAWG’s limitation and realize dynamic real-time reconfiguration of RF waveforms, we propose and demonstrate a novel approach of RF arbitrary-waveform generation based on an improved TPS system with an integrated dual parallel Mach–Zehnder modulator (DPMZM) and multi-tone inputs. By appropriately adjusting the DC bias voltages of DPMZM and the power values, as well as the center frequencies of the multi-tone inputs, any desired RF arbitrary waveform can be generated and reconfigured in real time. Proof-of-concept experiments on the generation of different user-defined waveforms with a sampling rate up to 27 GSa/s have been successfully carried out. Furthermore, the impact of modulation modes and higher-order dispersion on waveform fidelity is also discussed in detail.

Testing the Early Differentiation Hypothesis: A Case Study of a Spanish-English Bilingual Child

This paper contributes to the field of simultaneous bilingual first language acquisition (2L1). Specifically, it examines the developmental stages of a bilingual child in two languages, Spanish and English. The analysis is performed by analyzing bilingual acquisition data from CHILDES database with the CLAN program. The study aims to support several hypotheses proposed in the field of 2L1 (e. g., The Early Differentiation Hypothesis). The results show that the developmental stages of a bilingual child correspond to the stages of a monolingual child acquiring a language; the only difference is the number of languages that is being acquired. The data also show that the child’s caregivers use certain strategies in their socialization as the important prerequisite for 2L1 (e.g., frequency of input, discourse strategies and maximal engagement with a minority language available in the input). The results of the study confirm the Early Differentiation Hypothesis that argues for the language-specific morphosyntactic patterns in child’s grammar. The study has very important pedagogical implications for parents who raise their children in bi- and multilingual families.

Plasma-based base flow modification on swept-wing boundary layers: dependence on flow parameters

This work examines the control of cross-flow instabilities (CFIs) and laminar–turbulent transition on a swept wing, through the plasma-based base flow modification (BFM) technique. The effect of experimentally derived plasma body forces on the steady boundary layer base flow is explored through numerical simulations. Linear stability theory is subsequently used to predict the net BFM effect on CFIs. Based on these preliminary predictions, experiments are conducted in a low-turbulence wind tunnel where a spanwise-invariant plasma actuator is installed near the wing leading edge and operated at constant input voltage and frequency. Various flow parameters governing the plasma-based BFM technique are investigated, namely the Reynolds number, angle of attack and wavelength of excited stationary CFI modes. Stationary and travelling CFIs are quantified by planar particle image velocimetry while the transition topology and location are recorded by infrared thermography. The results confirm the stabilising effect of BFM on the swept-wing boundary layer. However, the plasma-based BFM is found to render the boundary layer more susceptible to travelling CFIs. In the presence of both net BFM effect and intrinsic plasma unsteady perturbations, the plasma-based BFM technique achieves transition delay with specific combinations of Reynolds number, angle of attack and wavelength of excited stationary CFI modes. The present findings provide insights into the fundamental principles of operating plasma actuators within the context of BFM control.

Compact design of universal gates with non-aligned gate technology and assessment of its performance in a TCAD Environment

ABSTRACT This paper proposes a technology computer-aided design (TCAD) of a compact single-device NAND and NOR logic gates in 215 nm device length along with speed and power performance results. The universal gates are designed with non-aligned double gate technology, and this helps to reduce the transistor count, giving a compact design structure. The static characteristics and input pattern sensitivity of the NAND and NOR structures are investigated in this work. By using graphical method, the optimal supply voltage of the universal gates was determined. The optimal supply voltage of the NAND gate and NOR gate was 0.9 V and 0.84 V, respectively, at an input frequency of 1 GHz. Further, the device scalability of the proposed structures was analysed. When compared to the past work, the proposed NAND gate and NOR gate improves delay performance by 25.02% and 35.63%, respectively. Additionally, a reduction of 10% and 16% in its supply voltage is achieved. Therefore, the proposed gate has potential to operate at higher frequency with reduced supply voltage, making them suitable in circuit applications.

Investigation of the conditionality of the problem of determining the parameters of a linear N-pole by input frequency characteristics

Investigation of the conditionality of the problem of determining the parameters of a linear N-pole by input frequency characteristics

Analytical solution of seismic power-based equation of motion

This research proposes an innovative power-based equation of motion (PBEM) for the single degree of freedom (SDOF) system considering seismic excitation. The external or input frequency function, solution of time, relation between external and kinetic powers, and equation of strain-power (SP) are obtained by solving the power balance equation (PBE). The external frequency function is related to both the particular and total solutions of the PBEM. The particular solution of PBEM is applied on the shake table test of the tunnel-soil-pile interaction (TSPI) model, real-scale test of 2-storied reinforced concrete frame structure, and case study of Bolu tunnel for the verification purpose. The differences in verification (PBEM and previous works) results are found to be 21.6 % for the real-scale test and 19.5 % for the case study. These differences may represent a reasonable agreement with verification. Also, the relationship between the kinetic and external powers is verified with the previous shake table test of steel cantilever column, whereas the difference in results is found to be 5 %. Finally, a design chart is proposed for predicting the input frequency function for various frequency ratios and damping.

Oral feeding practices in medically complex infants receiving prolonged high-flow nasal cannula support: A retrospective cohort study.

To characterise the feeding profile and care pathway for infants receiving prolonged high-flow nasal cannula (HFNC) respiratory support for management of a chronic condition at one facility from January to December 2021. Data regarding medical history, HFNC admission details (reason for HFNC, HFNC duration, flow rate), feeding outcomes and speech pathology care were collected from electronic records of HFNC-dependent infants (requiring HFNC ≥2-3 L/kg for ≥5 consecutive days). Infants with acute respiratory conditions (e.g. bronchiolitis) were excluded. This study included 24 participants (median corrected age at admission 5.3 weeks, range -6 to 18.6). Of these, 15 (60%) had a condition/s that affected more than one body system (e.g. congenital diaphragmatic hernia), requiring the care of multiple specialities. Median length of HFNC use was 37.5 days (range 11-188). Twenty (83.3%) infants were referred for speech pathology (SLP) input while on HFNC support. For those referred, frequency of SLP input was variable (0-3 sessions/week), and HFNC support requirements were the most common barrier to SLP intervention (n = 9, 45%). Twelve (54.5%) infants demonstrated improvement in their primary feeding method by discharge; however, only two (9.1%) infants were discharged on full oral feeds. This study demonstrates variability in oral feeding management in infants with prolonged HFNC-dependence at our centre. Respiratory support with HFNC was identified as a barrier to progressing oral feeding. Further research is required to determine if oral feeding can be safely undertaken in this cohort. This is imperative to ensure that long-term feeding outcomes are not negatively impacted by current practice.

High-Precision Angle Measurement for Position Control in Industrial Drives Systems with Shaft Resolver

Resolver is a shaft angle sensor, which is mechanically connected to the motor shaft and operates according to the induction principle. A high frequency sinusoidal signal is applied to its input and produces two signals in the form of sine and cosine at its output. The output signals include the angle information of the motor shaft. Using these signals, the shaft angle of the motor is determined. In the study, a sinusoidal signal at the 5 kHz frequency was applied to an input resolver as the conventional method. After, the fact that applied to two PWM signals which has a duty ratio d=0.5 at 20 kHz and 100 kHz frequency is proposed as different from the conventional method. These PWM signals are the input signals of the resolver. Thus, complex equipment will not be needed to produce the high frequency sinusoidal signal. With only a simple amplifier circuit, a high frequency input signal will be produced. More sensitive angle information will be obtained with high frequency stimulation. A simulation study of conventional and proposed methods has been performed in MATLAB/Simscape environment. As a result of the simulation study, the information on the motor angle obtained from both methods was compared by using figures and details. By increasing the applied PWM signal from 20 kHz to 100 kHz, measurement errors related to shaft angle change were minimized and more precise position information was obtained.

Do First Language, Word Frequency and Input Matter in Bilingual’s Language Acquisition?

The acquisition of morphosyntactic features, such as third-person singular (3SG) inflection, is a critical aspect of language development. While much research has focused on monolingual children’s acquisition of 3SG inflection, less is known about how bilingual children navigate this process, particularly those from non-inflectional first language (L1) backgrounds. Furthermore, two well established characteristics found in other bilingual groups: word frequency and L1 transfer are still remain unclear in the acquisition of 3SG inflection in Chinese-English bilingual groups. Addressing these gaps are crucial for understanding the unique challenges bilingual children face and the factors influencing their acquisition of English morphosyntatic feature. In this study, we employed corpus to analyze longitudinal naturalistic data from three Chinese-English bilingual children and one English monolingual child. We investigated the children’s use of 3SG inflection across obligatory contexts, examining the frequency of verb exposure in both parental input and a large corpus (COCA). Our results indicate that bilingual children, especially those from a non-inflectional L1 background, demonstrated delayed acquisition of 3SG inflection compared to monolingual counterparts. However, both groups showed better accuracy with high-frequency verbs, underscoring the importance of input frequency. Additionally, L1 transfer effects were evident in both monolingual children and bilingual children, with the bilingual children struggling more with verbs whose L1 lacked verb agreement. These findings suggest that both input frequency and L1 transfer play significant roles in shaping bilingual children’s acquisition of 3SG inflection. This study contributes to a deeper understanding of bilingual language development, with implications for language acquisition theory and educational practices, particularly in addressing the needs of children from diverse linguistic backgrounds.

Improved MSTOGI-PLL with enhanced control under non-ideal grid voltage conditions

Integration structure of second- and third-order generalized integrator phase-locking loop (MSTOGI-PLL) has received attention for the processing ability of harmonics and DC bias contained in grid voltage. However, due to that MSTOGI-PLL is sensitive to interharmonics and subharmonics, once low order harmonics dominate, the narrow bandwidth will result in slow response. Hence, based on the analysis on input and output frequency characteristics of existing MSTOGI, a frequency gain structure within the MSTOGI structure is added to improve the suppression ability, either to low-frequency or high-frequency harmonics. Secondly, in order to accelerate response and reduce overshoot of the output frequency of the phase-locked loop (PLL), a nonlinear PI dynamic regulator based on a hyperbolic threshold function is constructed. Furthermore, from the perspectives of voltage phase and frequency tracking error indicators, by comparing with three other types of PLL structures in weak grid application, the effectiveness of the proposed method is verified through simulation cases. Finally, a physical hardware platform based on dSPACE1104 is built to extract the grid voltage from the three-phase voltage regulating transformer, the theoretical derivation and simulation results are verified. The phase deviation is controlled within 0.44 rad s-1, and frequency deviation is controlled within 0.07 Hz.

Ultrasound pulse repetition frequency preferentially activates different neuron populations independent of cell type

Objective. Transcranial ultrasound (US) stimulation serves as an external input to a neuron, and thus the evoked response relies on neurons' intrinsic properties. Neural activity is limited to a couple hundred hertz and often exhibits preference to input frequencies. Accordingly, US pulsed at specific physiologic pulse repetition frequencies (PRFs) may selectively engage neurons with the corresponding input frequency preference. However, most US parametric studies examine the effects of supraphysiologic PRFs. It remains unclear whether pulsing US at different physiologic PRFs could activate distinct neurons in the awake mammalian brain.Approach. We recorded cellular calcium responses of individual motor cortex neurons to US pulsed at PRFs of 10, 40, and 140 Hz in awake mice. We compared the evoked responses across these PRFs in the same neurons. To further understand the cell-type dependent effects, we categorized the recorded neurons as parvalbumin positive fast spiking interneurons or putative excitatory neurons and analyzed single-cell mechanosensitive channel expression in mice and humans using the Allen Brain Institute's RNA-sequencing databases.Main results. We discovered that many neurons were preferentially activated by only one PRF and different PRFs selectively engaged distinct neuronal populations. US-evoked cellular calcium responses exhibited the same characteristics as those naturally occurring during spiking, suggesting that US increases intrinsic neuronal activity. Furthermore, evoked responses were similar between fast-spiking inhibitory neurons and putative excitatory neurons. Thus, variation in individual neuron's cellular properties dominates US-evoked response heterogeneity, consistent with our observed cell-type independent expression patterns of mechanosensitive channels across individual neurons in mice and humans. Finally, US transiently increased network synchrony without producing prolonged over-synchronization that could be detrimental to neural circuit functions.Significance. These results highlight the feasibility of activating distinct neuronal subgroups by varying PRF and the potential to improve neuromodulation effects by combining physiologic PRFs.

Design and simulation of a Ka-band frequency doubling gyroklystron amplifier

The design methodology of a Ka-band frequency doubling two cavity gyroklystron has been discussed in this paper. In this study, the amplifier’s design and simulation are accomplished by employing nonlinear analysis and validated using particle-in-cell simulation techniques. The output cavity functions in the TE02 mode at two times the input signal frequency at the second harmonic of the cyclotron frequency, while the input cavity is powered by a 17.5 GHz source and functions in the TE01 mode at the first harmonic of the cyclotron resonance. The device’s performance has been examined both in the presence and in the absence of a beam. A number of factors were taken into account in order to optimize the interaction structure dimension to reach the device’s targeted performance. By adjusting the structural features and electron beam parameters, the device’s RF output power is assessed in an effort to increase efficiency. Simulation results estimate that the device displays a gain of 21.5 dB, an efficiency of 21.6%, a power of 227 kW, and a −3 dB bandwidth of ∼0.3%.

A 10-bit 70-MS/s SAR ADC with Reference Buffer in 40nm CMOS

Abstract A 10-bit 70-MS/s successive approximation register (SAR) analog-to-digital converter (ADC) with reference buffer is presented in this paper. Segmented capacitive DAC with redundant 2bits is designed to relax the design of reference buffer. A hybrid switching sequence is applied to the ADC to optimize power consumption. The Measurement results Show that the core SAR ADC achieves 48.52 dB SNDR and 56.67 dB SFDR at 70 MS/s sampling rate and Nyquist input frequency, consuming 2.50mW power consumption, achieving a FoM of 163.6 fJ/step. The ADC occupies an active area of 0.017 mm2 in 40nm CMOS technology.

Robust 3-D Path Following Control Framework for Magnetic Helical Millirobots Subject to Fluid Flow and Input Saturation.

Precise trajectory control is imperative to ensure the safety and efficacy of in vivo therapy employing the magnetic helical millirobots. However, achieving accurate 3-D path following of helical millirobots under fluid flow conditions remains challenging due to the presence of the lumped disturbances, encompassing complex fluid dynamics and input frequency saturation. This study proposes a robust 3-D path following control framework that combines a disturbance observer for perturbation estimation with an adaptive finite-time sliding mode controller for autonomous navigation along the reference trajectories. First, a magnetic helical millirobot's kinematic model based on the 3-D hand position approach is established. Subsequently, a robust smooth differentiator is implemented as an observer to estimate disturbances within a finite time. We then investigate an adaptive finite-time sliding mode controller incorporating an auxiliary system to mitigate the estimated disturbance and achieve precise 3-D path tracking while respecting the input constraints. The adaptive mechanism of this controller ensures fast convergence of the system while alleviating the chattering effects. Finally, we provide a rigorous theoretical analysis of the finite-time stability of the closed-loop system based on the Lyapunov functions. Utilizing a robotically-actuated magnetic manipulation system, experimental results demonstrate the efficacy of the proposed approach in terms of the control accuracy and convergence time.

Multiparameter cascaded quantum interferometer

We theoretically propose a multiparameter cascaded quantum interferometer in which a two-input and two-output setup is obtained by concatenating 50:50 beam splitters with n independent and adjustable time delays. A general method for deriving the coincidence probability of such an interferometer is given based on the linear transformation of the matrix of beam splitters. As examples, we analyze the interference characteristics of one-, two-, and three-parameter cascaded quantum interferometers with different frequency correlations and input states. Some typical interferograms of such interferometers are provided to reveal richer and more complicated two-photon interference phenomena. This work offers a general theoretical framework for designing versatile quantum interferometers and provides a convenient method for deriving the coincidence probabilities involved. In principle, arbitrary two-input and two-output experimental setups can be designed with the framework. Potential applications can be found in the complete spectral characterization of two-photon states, multiparameter estimation, and quantum metrology.

X-Band Single Chip Integrated Pulsed Electron Spin Resonance Microsystem.

We report on the design and characterization of a single chip integrated pulsed electron spin resonance detector operating at 9.1 GHz. The microsystem consists of an excitation microcoil, a detection microcoil, a low noise microwave preamplifier, a mixer, and an intermediate frequency (IF) amplifier. The chip area is about 0.7 mm2. To exemplify its possible applications, we report the results of single pulse, Rabi nutation, Hahn echo, two echoes, Carr-Purcell, and inversion recovery echo experiments performed on 0.02 and 0.05 nL samples of α, γ-bisdiphenylene-β-phenylallyl (BDPA) and 1% BDPA in polystyrene (BDPA:PS) at room temperature. The measured spin sensitivity is about 8 × 107 spins/Hz1/2 on a sensitive volume of about 0.1 nL. The microsystem power consumption is less than 100 mW, the radio frequency (RF) input bandwidth is 8.8 to 9.8 GHz, the IF output bandwidth is DC to 350 MHz, and the deadtime is less than 30 ns.

Nonreciprocal synchronization in embryonic oscillator ensembles

Synchronization of coupled oscillators is a universal phenomenon encountered across different scales and contexts, e.g., chemical wave patterns, superconductors, and the unison applause we witness in concert halls. The existence of common underlying coupling rules defines universality classes, revealing a fundamental sameness between seemingly distinct systems. Identifying rules of synchronization in any particular setting is hence of paramount relevance. Here, we address the coupling rules within an embryonic oscillator ensemble linked to vertebrate embryo body axis segmentation. In vertebrates, the periodic segmentation of the body axis involves synchronized signaling oscillations in cells within the presomitic mesoderm (PSM), from which somites, the prevertebrae, form. At the molecular level, it is known that intact Notch-signaling and cell-to-cell contact are required for synchronization between PSM cells. However, an understanding of the coupling rules is still lacking. To identify these, we develop an experimental assay that enables direct quantification of synchronization dynamics within mixtures of oscillating cell ensembles, for which the initial input frequency and phase distribution are known. Our results reveal a "winner-takes-it-all" synchronization outcome, i.e., the emerging collective rhythm matches one of the input rhythms. Using a combination of theory and experimental validation, we develop a coupling model, the "Rectified Kuramoto" (ReKu) model, characterized by a phase-dependent, nonreciprocal interaction in the coupling of oscillatory cells. Such nonreciprocal synchronization rules reveal fundamental similarities between embryonic oscillators and a class of collective behaviors seen in neurons and fireflies, where higher-level computations are performed and linked to nonreciprocal synchronization.