High Fundamental Frequency Research Articles

Nonlinear Finite Element Analyses of Prestressed Concrete Beams Strengthened with CFRP Laminate

Nonlinear finite-element (FE)-based quasi-static and vibration analyses of prestressed concrete beams with carbon fiber-reinforced polymer (CFRP) laminate are conducted. To establish nonlinearities in concrete and prestressing steel material properties and concrete–steel interfaces in FE modeling, numerical models of reinforced concrete (RC) and prestressed concrete (PSC) beams are developed, and their response is assessed with experimental results. The established FE model is then extended so as accurately to model CFRP laminate and the nonlinear interaction at concrete–CFRP interfaces between RC and PSC beams. Cohesive interface elements capable of showing delamination failure are introduced to model the adhesion between a concrete beam and the CFRP laminate at its soffit. Ignoring such interaction overestimates the load-carrying capacity of the beam apart from its inability to capture the delamination. The effect of the prestressing force, location and profile of prestressing tendons on the modal frequencies of unstrengthened and CFRP-strengthened beams is studied. Strengthened beams have higher fundamental frequencies, and their modal frequencies are independent of prestressing force, varying significantly with the location and profile of tendons.

Vocal repertoire and sound characteristics in the variegated cardinalfish, Fowleria variegata (Pisces: Apogonidae).

The variegated cardinalfish Fowleria variegata produces grunt and hoot calls during agonistic and courtship interactions. Both sounds are tonal and occur as single and multiunit calls. Grunts are of short duration with variable frequency spectra. Hoots are longer, have a higher fundamental frequency, and a more developed harmonic structure. Agonistic grunt calls and short hoot calls (1-2 hoots) are produced during chases and when striking an individual or a mirror. Grunts are produced primarily in male-female and mirror-image encounters, and short hoot calls are produced primarily in male-male interactions. During the reproductive period, long hoot calls (three and four hoots) are the main sound type in a mix-sexed tank and at Dongsha Atoll. These are likely produced by males because isolated females are silent, and isolated males emit long hoot calls. Courtship interactions are mostly silent, and males are silent after capturing eggs for oral brooding. Tank sounds peak at dusk to early evening with a smaller peak at noon, although there are dusk and dawn peaks at Dongsha Atoll. Tank sounds exhibit a semilunar rhythm with peaks at the new and full moon. Other cardinalfish species from the atoll produce grunts but not hoot calls.

Effect of mouse nerve growth factor combined with the exposure of the external branch of superior laryngeal nerve on voice changes after thyroidectomy: a prospective non-randomized controlled trial.

The superior laryngeal nerve (SLN) injury may also affect vocal fold function and voice quality. It is efficient yet simple approach to expose the external branch of the superior laryngeal nerve (EBSLN). Neurotrophic agent mouse nerve growth factor (mNGF) to treat patients after thyroid surgery, and found it had significant efficacy in improving the voice of patients. However, the potential effectiveness and safety of mNGF combined with EBSLN were unclear. In this study, 96 patients who suffered from hoarseness after thyroidectomy at Hangzhou First People's Hospital between January 2018 and October 2019 were screened and divided into the control group and the observation group by patients' choice. In the control group, the SLN was not exposed. In the observation group, the SLN was exposed. The mNGF treatment was administered for observation group once a day at 20 µg each time for 4 weeks. The data of acoustic voice indicators was analysis by univariate analyses. Patients in both groups were followed up for more than 6 months. The rate of SLN damage was compared between two groups. The baseline clinical characteristics of the two groups showed no statistic difference. The results showed that the fundamental frequency was significantly lower 1 month after surgery than 3 days after surgery in both groups. The fundamental frequency perturbation, shimmer, maximum phonation time, highest fundamental frequency, and dysphonia severity index in 1 month after surgery were significantly higher than they were 3 days after surgery (all P<0.001). There was no significant difference in the postoperative harmonic-to-noise ratio between the 2 groups (P=0.426). MNGF combined with the exposure and protection of the EBSLN effectively may prevent voice damage after thyroid surgery.

A design-oriented method for response prediction of light-weight timber floors under bouncing excitation

Owing to the light weight and high fundamental frequency, timber floors exhibit impulse-like responses under human-induced excitation, which is different with the resonance-like responses for heavy concrete structures. The vibration serviceability of timber floors thus needs to be considered in a different manner. Many design codes for timber structures have required that the static displacement or dynamic response under human excitation should be limited within a threshold for the purpose of serviceability, while failing to provide appropriate method for predicting structural responses considering various affecting factors. Inspired by the idea of response spectrum, this paper proposed a design-oriented method for the peak acceleration prediction of high-frequency floors under human bouncing excitation. The prediction can be obtained for any desired confidence level. Statistical analysis shows that the acceleration responses are mostly dependent on structural fundamental frequency, structural damping ratio, and excitation frequency, which are considered in the proposed mathematical model. The application procedure and the experimental assessment of the proposed model are provided, showing the decent applicability of the proposed method.

Acoustic cues to the perception of Danish stød

This study examines the effect of F0 and creak (raspiness) on Danish stød perception. Stød is typically characterized by high fundamental frequency (F0) at the beginning of the syllable and low F0, often with creaky phonation, at the end of the syllable (Fischer-Jørgensen, 1989). However, it is not clear how these acoustic cues, high F0 at rhyme onset, low F0 at rhyme offset, and creak, contribute to the percept of stød for listeners. A nonce word ABX task and a perceptual rhyming task were conducted. Results from the ABX task indicate that nonce words with high-mid or high-low F0 contours and added raspiness (Corretge, 2012) or a sustained high F0 with or without raspiness were more likely to be considered the “same” as naturally produced nonce words with stød. In the rhyming task, nonce words with high F0 and raspiness were significantly more likely to be considered as rhyming with a naturally produced real word with stød for all tonal contours tested. Overall, the results indicate that both high F0 onset{Citation} and creaky phonation contribute to the stød percept. Furthermore, both cues were almost always needed to increase stød responses in both tasks, suggesting little evidence of cue trading.

Cat vocalization in aversive and pleasant situations

Vocalization may transmit information from the emitting animal, including information about his or her emotional state. This study aimed to compare the vocal and the behavioral responses of domestic cats during an aversive and a pleasant situation. A total of 74 cats (29 males and 45 females) in the city of Curitiba, Southern Brazil, participated in the study; 68 (26 males and 42 females) were divided into 2 treatments: an aversive situation (AS), which was a car transport event where the cat was in a crate, or a pleasant situation (PS), where the cat was offered a snack. The other animals (3 males and 3 females) participated in both situations. Behavioral signals and individual vocalizations were registered through video recordings and further evaluated in each scenario. Cats in the PS had a higher fundamental frequency of vocalizations (10.1%), a lower range of pitches (tessitura) (33.9%) and twice the rate of head movement rates as compared to AS. For call duration there was significant interaction between treatment and sex. Additionally, there were differences in the vocal parameters and the behavioral signals due to sex, age, and coat color. Females and kittens have higher fundamental frequencies may be due to anatomical characteristics. Solid-colored coated cats presented higher fundamental frequency than other coat colors. Overall, vocal parameters and behavioral signals seem useful indicators for studying the emotions of cats in different situations. Further studies are warranted to understand the subtleties of cat vocalization across sex, age, and coat color.

Acoustic characteristics of sound produced by males of Bactrocera oleae change in the presence of conspecifics

Males of the olive fruit fly Bactrocera oleae vibrate and stridulate their wings at dusk producing sounds different from flight sounds with no confirmed behavior role. We recorded and performed a temporal-spectral analysis of this sound. Sound produced by male wing vibration/stridulation consists of intermittent pulses of highly variable duration and of fundamental frequency of around 350 Hz. Flight sound has a much lower fundamental frequency of approximately 180 Hz. Males begin to display wing vibration and sound production at the beginning of their sexual maturity at the 5th day of their age. This behavior is more pronounced in the presence of another conspecific male and observed less in male–female pairs or in solitary males. Broadcasts of the recorded sound did not attract flies of either sex. The highest fundamental frequency was found in association with wing vibrations emitted by male–male pairs, followed by those emitted by male–female pairs and then solitary males, which showed the lowest frequency values. The mean pulse duration and interpulse interval were shorter in male–male pairs than in male–female pairs. We assume that the male wing vibration and the produced signal, apart from its possible role in the courtship of the females, could also be associated with male–male interactions for territorial and rival activities, for which further experiments are required.

Novel Axial Flux-Switching Permanent Magnet Machine for High-Speed Applications

Conventional high-speed flux-switching machines have either a high fundamental frequency or more even harmonics. This paper proposes a novel six-slot four-pole axial flux-switching permanent magnet machine for high-speed applications. The machine, consisting of two radially distributed stators and one rotor, can effectively eliminate even harmonics in the flux linkage. First, the structural parameters that affect the performance of the motor are determined by the equivalent magnetic circuit method, and the optimal structural parameters of the motor are obtained by simulation optimization. Then, through finite element analysis, the three-dimensional model of the proposed machine is built, and the static electromagnetic characteristics are analyzed, including magnetic field distribution, flux linkage, back-electromotive force, cogging torque, and efficiency. The simulation results show that the total harmonic distortion of the flux linkage and back-electromotive force waveforms of the proposed novel machine is 2.2% and 9.8% respectively. The cogging torque of the optimal model is only 9 N.

Perceiving Body Height From Connected Speech: Higher Fundamental Frequency Is Associated With the Speaker's Height.

To a certain degree, human listeners can perceive a speaker's body size from their voice. The speaker's voice pitch or fundamental frequency (Fo) and the vocal formant frequencies are the voice parameters that have been most intensively studied in past body size perception research (particularly for body height). Artificially lowering the Fo of isolated vowels from male speakers improved listeners' accuracy of binary (i.e., tall vs not tall) body height perceptions. This has been explained by the theory that a denser harmonic spectrum provided by a low pitch improved the perceptual resolution of formants that aid formant-based size assessments. In the present study, we extended this research using connected speech (i.e., words and sentences) pronounced by speakers of both sexes. Unexpectedly, we found that raising Fo, not lowering it, increased the participants' perceptual performance in two binary discrimination tasks of body size. We explain our new finding in the temporal domain by the dynamic and time-varying acoustic properties of connected speech. Increased Fo might increase the sampling density of sound wave acoustic cycles and provide more detailed information, such as higher resolution, on the envelope shape.

High Fundamental Frequency (HFF) Monolithic Quartz Crystal Microbalance with Dissipation Array for the Simultaneous Detection of Pesticides and Antibiotics in Complex Food.

As in the case of the food industry in general, there is a global concern about safety and quality in complex food matrices, such as honey, which is driving the demand for fast, sensitive and affordable analytical techniques across the honey-packaging industry. Although excellent techniques such as liquid chromatography-tandem mass spectrometry (LC-MS/MS) are available, these are located in centralized laboratories and are still lacking in speed, simplicity and cost-effectiveness. Here, a new approach is presented where a competitive immunoassay is combined with a novel High Fundamental Frequency Quartz Crystal Microbalance with Dissipation (HFF-QCMD) array biosensor for the simultaneous detection of antibiotics and pesticides in honey. Concretely, thiabendazole and sulfathiazole residues were monitored in spiked honey samples. Results revealed that HFF-QCMD arrays provide a complementary and reliable tool to LC-MS/MS for the analysis of contaminants in these kinds of complex matrices, while avoiding elaborate sample pre-treatment. The good sensitivity achieved (I50 values in the 70–720 µg/kg range) and the short analysis time (60 min for 24 individual assays), together with the ability for multiple analyte detection (24 sensor array) and its cost-effectiveness, pave the way for the implementation of a fast on-line, in situ routine control of potentially hazardous chemical residues in honey.

Design and Development of a Multiphase Inverter for Automotive Applications

This work describes the development of a multiphase inverter that can operate as a platform for driving and testing electrical machines with up to 15 phases, in addition, it can operate with a fundamental frequency of up to 1 kHz and a switching frequency of 100 kHz. Therefore, a multiphase voltage source inverter (VSI) topology using SiC MOSFETs and approved components for automotive applications was designed and constructed. The developed platform is composed of independent power modules and a control module with technology that uses only a single microcontroller capable of generating all signals with pulse width modulation (PWM). To validate the inverter, experimental tests were carried out with a YASA (Yokeless and Segmented Armature) machine that can operate with 3, 5, or 15 phases and also with multi-star connections, one with three independent systems of five phases and another with five independent three-phase systems. Experimental results show that the inverter is capable of driving and testing multiphase machines with a wide variety of electrical connections using high fundamental and carrier frequencies. Therefore, the developed platform is an important tool that allows the testing of multiphase and multi-star electrical machines operating under the most diverse configurations and operating conditions.

High Frequency (100, 150 MHz) Quartz Crystal Microbalance (QCM) Piezoelectric Genosensor for the Determination of the Escherichia coli O157 rfbE Gene

Escherichia coli O157 (E. coli O157) is responsible for outbreaks of high morbidity in food-borne infections. The development of sensitive, reliable, and selective detection systems is of great importance in food safety. In this work, two high fundamental frequency (HFF) piezoelectric genosensors (100 and 150 MHz) were designed and validated for the rfbE gene detection, which encodes O-antigen in E. coli O157. HFF resonators offer improved sensitivity, small sample volumes, and the possibility of integration into lab-on-a-chip devices, but their sensing capabilities have not yet been fully explored. This HFF-QCM genosensor uses the method of physisorption based on the union between the streptavidin and the biotin to immobilize the genetic bioreceptor on the surface and detect its hybridization with the target sequence. Parameters such as molecular coating, specificity, and variability were tested to enhance its performance. Although both genosensors evaluated are able to determine the target, the 100 MHz device has a higher response to the analyte than the 150 MHz platform. This is the first step in the development of an HFF-QCM genosensor that may be used as a trial test of E. coli O157 in large batches of samples.

A Medium-Voltage Current Source Inverter for Synchronous Electrostatic Drives

Macro scale synchronous electrostatic machines (SEMs) require medium voltage (5kV) and high fundamental frequencies (high pole number ~ 96) to be competitive with traditional electromagnetic machines. This paper focuses on the design, modeling, and characterization of a medium voltage current source inverter hardware platform to meet the low current and high frequency requirements of SEMs. The inverter stage utilizes JFET super cascodes for the medium voltage switches. A full-bridge front end regulates the necessary dc-link current and provides some of the voltage gain from the low voltage dc input. A sensitivity analyses shows that the system losses have a quadratic dependence on output voltage and a linear dependence on switching frequency and dc-link current. Minimal dependence on output power and fundamental frequency were measured. Averaged modeling shows a right-half-plane pole exists for the dc-link control. Two methods for stabilizing the machine drive were proposed and validated. Active damping via virtual resistance on the dc link was used to shift the pole to the left half plane. The second method utilizes q-axis voltage decoupling to remove the voltage disturbance of the inverter controller on the dc-link current. The impacts on system stability and disturbance rejection were measured and correlate with modeling.

Ferromagnetic resonance over-voltage identification method based on Gram angle field

In neutral point non-grounding systems with 35 kV and below, ferromagnetic resonance over-voltage faults often occurs, which brings safety hazards to power systems. Ferromagnetic resonance occurs for a short time and is similar to other faults in the power system and is not easy to be detected by direct observation. Deep learning has obvious advantages in image recognition and classification, but it is difficult to deal with over-voltage one-dimensional time series monitored in power system, and a deep learning recognition model based on Gram angle field and improving Convolutional Neural Network (CNN) structure is proposed, the voltage time series is converted into two-dimensional image, and the voltage classification task is performed by extracting image features and entering them into two channels of CNN-SPP (Spatial Pyramid Pooling). The two-channel structure solves the problem of high-dimensional time series learning, SPP solves the problem that CNN requires the input over-voltage conversion image must be the same size, and optimizes the network structure and parameters to obtain the optimal identification model. Finally, the experimental comparison shows that the ferromagnetic resonant over-voltage voltage recognition based on Gram angle field and improving CNN has higher recognition accuracy than other time domain and frequency domain characteristic algorithms. The high frequency, division frequency and fundamental frequency ferroresonance identification accurate rate based on the proposed method is 94.2%, 93.8% and 90.5% respectively.

Full-Bandwidth Mission Profile Emulation of the Electric Machine System With Voltage Reference Signal Transmission

Electric machine emulation (EME) is becoming a popular solution in advanced testing and validation of power-electronics-based machine drive systems. In terms of a typical EME, the stator current references are first calculated in response to the sampled terminal voltage, and then, are electrically generated by power electronics converters. In this type of structure, closed-loop current control and low-pass sampling for the voltage are inevitably introduced, resulting in distortion in frequency-domain behaviors of EME. Consequently, the steady-state performance under a high fundamental frequency, and the dynamic performance under load transients, may deviate from those of the target machine system. In this article, the bandwidth limitations of the typical EME are identified and analyzed in detail, and a novel structure that realizes full-bandwidth mission profile emulation is proposed. Theoretical analyses are given to prove that the frequency-domain characteristics of the proposed structure would be identical to the actual machine systems, which allows for the extended operating range of mission profile emulation. Simulation and experimental results are provided to validate the effectiveness of the proposed method.

Stød Timing and Domain in Danish

This study investigates the timing of stød, a type of phonological nonmodal phonation related to creaky voice in Danish, relative to the syllable. Stød-bearing syllables are characterized by high fundamental frequency (F0) and modal phonation at the beginning of the syllable followed by nonmodal, often creaky phonation and low F0 towards the end of the syllable (the stød phase proper). However, the timing of these two phases relative to the syllable and to each other has been debated. To investigate this, F0 throughout the word and the timing of the stød phase proper relative to the syllable were analyzed in five types of monosyllabic words. The results show that across word types the first stød phase (high F0) coordinates with the syllable rhyme onset, whilst the second phase is timed to the center of the sonorant rhyme, in contrast to previous hypotheses of stød timing. This relationship is formalized using the framework of Articulatory Phonology. In doing so, two additions to the theory are proposed to account for the biphasic nature of stød and the timing of the stød phase proper relative to the syllable.

Acoustic Array Biochip Combined with Allele-Specific PCR for Multiple Cancer Mutation Analysis in Tissue and Liquid Biopsy.

Regular screening of point mutations is of importance to cancer management and treatment selection. Although techniques like next-generation sequencing and digital polymerase chain reaction (PCR) are available, these are lacking in speed, simplicity, and cost-effectiveness. The development of alternative methods that can detect the extremely low concentrations of the target mutation in a fast and cost-effective way presents an analytical and technological challenge. Here, an approach is presented where for the first time an allele-specific PCR (AS-PCR) is combined with a newly developed high fundamental frequency quartz crystal microbalance array as biosensor for the amplification and detection, respectively, of cancer point mutations. Increased sensitivity, compared to fluorescence detection of the AS-PCR amplicons, is achieved through energy dissipation measurement of acoustically "lossy" liposomes binding to surface-anchored dsDNA targets. The method, applied to the screening of BRAF V600E and KRAS G12D mutations in spiked-in samples, was shown to be able to detect 1 mutant copy of genomic DNA in an excess of 104 wild-type molecules, that is, with a mutant allele frequency (MAF) of 0.01%. Moreover, validation of tissue and plasma samples obtained from melanoma, colorectal, and lung cancer patients showed excellent agreement with Sanger sequencing and ddPCR; remarkably, the efficiency of this AS-PCR/acoustic methodology to detect mutations in real samples was demonstrated to be below 1% MAF. The combined high sensitivity and technology-readiness level of the methodology, together with the ability for multiple sample analysis (24 array biochip), cost-effectiveness, and compatibility with routine workflow, make this approach a promising tool for implementation in clinical oncology labs for tissue and liquid biopsy.

Analysing Efficiency and Reliability of High Speed Drive Inverters Using Wide Band Gap Power Devices

Within the project ‘ARIEL’ an electrical turbo compressor unit for fuel cell applications is deeply investigated. The necessary drive inverter is especially designed for high fundamental frequency and high switching frequency to cope with the requirements of the implemented electrical machine. This paper presents investigations on the inverter’s efficiency and its prospective lifetime at different stages of the development. In the design process different wide band gap power semiconductor devices in discrete packages are evaluated in terms of the achievable power density and efficiency, both by simulations and measurements. Finally, an optimised design using surface mount silicon carbide MOSFETs is developed. Compared to a former inverter design using silicon devices in a three-level topology, the power density of the inverter is significantly increased. The lifetime of power electronic systems is often limited by the lifetime of the power semiconductor devices. Based on loss calculations and the resulting temperature swing of the virtual junction the lifetime of the inverter is estimated for the most frequent operating points and for different mission profiles.

Analysis and Experimental Verification of a Conventional Inverter With Output LC Filter to Drive Ironless Stator Axial-Flux PM Motor

Ironless stator axial-flux permanent magnet (PM) machines are becoming a promising choice in aerospace and automotive applications. However, they come with the characteristic of extremely small armature inductance, which will result in a challenging difficulty to drive with the conventional inverter. Considering the limitation on increasing the switching frequency of high-power devices, a practical and cost-effective power circuit for driving an axial-flux ironless stator PM motor is developed for the application with high dc-link voltage, high-power level, and high fundamental frequency. A new and simple control strategy of the inverter with output inductor–capacitor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> ) filter is studied to achieve a well steady and dynamic performance for driving ironless stator PM motors. The dual closed loop of the phase current of the motor and the branch current of capacitors ensures the stability and torque control of the system. Due to the dual-loop current regulator, the maximum torque per ampere control is achieved. Meanwhile, the sinusoidal current with low harmonic content injected into the armature winding is of great significance for improving the performance of ironless stator AFPM motor. It proves that the development of the power circuit topology and effective control method provides an available solution for ironless stator motors or high-speed motors with small inductance.

An Efficient Classification of Neonates Cry Using Extreme Gradient Boosting-Assisted Grouped-Support-Vector Network.

The cry is a loud, high pitched verbal communication of infants. The very high fundamental frequency and resonance frequency characterize a neonatal infant cry having certain sudden variations. Furthermore, in a tiny duration solitary utterance, the cry signal also possesses both voiced and unvoiced features. Mostly, infants communicate with their caretakers through cries, and sometimes, it becomes difficult for the caretakers to comprehend the reason behind the newborn infant cry. As a result, this research proposes a novel work for classifying the newborn infant cries under three groups such as hunger, sleep, and discomfort. For each crying frame, twelve features get extracted through acoustic feature engineering, and the variable selection using random forests was used for selecting the highly discriminative features among the twelve time and frequency domain features. Subsequently, the extreme gradient boosting-powered grouped-support-vector network is deployed for neonate cry classification. The empirical results show that the proposed method could effectively classify the neonate cries under three different groups. The finest experimental results showed a mean accuracy of around 91% for most scenarios, and this exhibits the potential of the proposed extreme gradient boosting-powered grouped-support-vector network in neonate cry classification. Also, the proposed method has a fast recognition rate of 27 seconds in the identification of these emotional cries.