Fundamental Frequency Values Research Articles

Monitoring the behaviour of seven storeyed RC frame subjected to reversed cyclic loading by nonlinear NDT

Large-scale structures are more prone to risk than small-scale structures due to their increased weight, stiffness and ductility parameters. The main focus of this investigative study is on the structural monitoring of a building using the non-destructive method of non-linear ultrasonic pulse velocity. A single-bay seven-storeyed frame model subjected to reverse cyclic loading of varying amplitudes is monitored by non-linear ultrasonic technique based on third harmonic wave generation. The critical nodes are identified in two different ways: the points of possible plastic hinge formation (PPPHF) through the theoretical background of plastic hinge analysis and the highly sensitive regions in structures (HSR) through numerical analysis. The common nodes of PPPHF and HSR are considered to monitor the structure. The invisible primary structural damage in the initial stage and the visible structural damage up to ultimate load are observed using non-linear ultrasonic waves. The fundamental frequency value and the third harmonic frequency value are observed and processed in MATLAB in the form of a Fast Fourier Transform (FFT) algorithm. The relationship between the condition of the structure and the ratio of third harmonic parameter, load and displacement is compared. In the initial stage of loading, only slight change or no variation in third harmonic ratio is observed at the observation points indicating material disintegration. This varies consistently up to the development of visible cracks and the same varies inconsistently on further loading after the appearance of visual cracks.

Metamorphic bedrock geometry of Santorini using HVSR information and geophysical modeling of ambient noise and active-source surface-wave data

Santorini is the most active volcano of the Southern Aegean Volcanic Arc, with volcanic material that has accumulated during the last 600+ Kyrs on top of the pre-volcanic Santorini island. The geometry of the pre-volcanic basement not only provides constraints on the volcanic history, but is also fundamental for seismic hazard assessment, as it partly controls site-effects on strong ground motions. We investigate the geometry of the metamorphic (Cycladic) basement of Santorini using information from both passive (noise) and active source data. We performed a large number (∼280) of single-station ambient noise measurements and collected additional data from 42 previous studies to compute the Horizontal-to-Vertical Spectral Ratio (HVSR) curves. The majority of the recovered HVSR curves show prominent spectral ratio peaks (locally larger than 7–8) indicating a large impedance contrast between pyroclastic volcanic strata and bedrock metamorphic formations. We also performed active (MASW) and passive (Noise Array) surface wave measurements at 4 selected sites to determine local dispersion curves. To find the 1D Vs structure from the surface down to the metamorphic bedrock we performed a joint Monte Carlo inversion of the dispersion curves and the fundamental frequency (f0HVSR) values from the HVSR curves. These models, as well as deep borehole information and HVSR data along the caldera cliff, where the thickness and stratigraphy of the volcanic formations above the bedrock can be directly observed, allowed us to determine a linear relationship between the thickness of the pyroclastic formations and their fundamental resonance period for central-southern Santorini. The resulting geometry of pre-volcanic island shows deep basins around the pre-Alpine bedrock outcrop (Profitis Ilias) and generally agrees with recent results from larger-scale tomographic and gravity data but with some significant local differences. The basins are 200+ meters thick in the Kamari and Perissa area (southeastern Santorini) and >400 m thick in the central (Fira-Imerovigli) area, while there is a thick (∼70-130 m) pyroclastic layer on top of a metamorphic basement “plateau” in the Megalochori area.

Improved Design of a Six-Phase Squirrel Cage Induction Motor With Pseudo-Concentrated Windings

Pseudoconcentrated winding seems to be a promising solution for the six-phase induction motors (6PIMs) because it exposes advantages of concentrated windings (CWs) over the distributed windings (DWs). In addition, this winding has an air gap flux density with higher amplitude of the fundamental frequency and lower total harmonic distortion value compared to the conventional CWs, which results in considerably higher performance. In this article, a design algorithm and an analytical model are developed for a 6PIM to cope with pseudoconcentrated winding. Then, a sensitivity analysis is performed to enhance motor performance. The designed motor with pseudoconcentrated winding shows superior performance compared to the baseline motor with the DWs. The designed motor is manufactured to verify the accuracy of the design procedure, performance calculation, and finite element simulation results.

Nonlinear Thermoelastic Numerical Frequency Analysis and Experimental Verification of Cutout Abided Laminated Shallow Shell Structure

Abstract The cutout and temperature loading influences on the nonlinear frequencies of the laminated shell structures are predicted numerically using two different types of geometrical nonlinear strain-displacement relationships to count the large deformation. The displacement of any generic point on the structural panel is derived using the third-order shear deformation theory (TSDT). Moreover, the direct iterative method has been adopted to obtain the nonlinear eigenvalues in conjunction with the isoparametric finite element (FE) steps. The present analysis includes the effect of temperature and the temperature-dependent composite elastic properties on the thermoelastic frequencies. This study intends to establish the Green-Lagrange type of nonlinear strain's efficacy in computing the nonlinear frequency of layered structure with and without cutout instead of von-Karman strain kinematics. The numerical model's validity has been established by comparing the results to previously published results. In addition, experimentally obtained fundamental frequency values of a few modes are compared to numerical proposed numerical results under the thermal loading. Finally, the effects of cutout (shape and size) and the associated structural geometrical parameters on the nonlinear thermal frequency responses of the laminated structure are expressed in the final output form.

The impact of the conversion starting threshold on the estimation of the RMS value

This paper presents an optimal solution for the selection of the starting instance of the analog-to-digital conversion for the purpose of the estimation of the root mean square (RMS) value of an arbitrary periodic signal when the ratio of the sampling frequency and the signal's fundamental frequency value is low and a non-integer. This selection of the optimal starting threshold is discussed in the context of the application of the two most common numerical methods used in measurement instrumentation today: the rectangular method and the trapezoidal rule. The appropriate threshold selection results in a significantly reduced measurement uncertainty of the estimated RMS value and improved measurement performances without necessitating major modifications or upgrade of the existing hardware. All theoretical results have been experimentally validated. The research is an original contribution to the field of mathematical modeling of methods implemented in microprocessor used in contemporary instrumentation.

Identifikasi Jenis Kelamin Secara Real Time Berdasarkan Suara Pada Raspberry Pi

The voice of each speaker has a unique specific character, influenced by gender, age, emotion, dialect, etc. The use of voice-based gender identification is growing rapidly, such as in the fields of security systems, speech recognition, artificial intelligence, etc. However, in speech processing, there are difficulties where the characteristics of the speech signal based on increasing age are difficult to determine accuracy, and there are overlapping fundamental frequency values between males and females. In this research, modeling of a gender identification system based on voice in real-time has been carried out on a Raspberry Pi device. This system is implemented by 2 methods, namely the YIN algorithm and feature extraction of Mel-Frequency Cepstral Coefficient (MFCC). The test results showed that the success of identification in the tuning parameters of scheme two is better than the first scheme by narrowing the overlapping frequency parameters. In the female test data in the closed test, the accuracy is from 98% to 100%, then in the open test starts from 92% to 96%. Meanwhile, the test data for the male closed test increased from 92% to 98%, and the open test started at 90% and rose to 94%. It indicates that the data used in this research is more suitable to use the second scheme parameter tuning to increase the accuracy of the results.

Effect of thermal environment on the asymmetric vibration of temperature-dependent two-dimensional functionally graded annular plate by Chebyshev polynomials

In the present paper, an accurate numerical technique is employed to analyze the effect of two-dimensional temperature variation on the free asymmetric vibrations of functionally graded (FG) annular plates using the first-order shear deformation theory. The temperature-dependent mechanical properties of the plate material are graded along the thickness and radial directions. The governing differential equations for asymmetric motion are derived from Hamilton’s principle and the exact solution for the two-dimensional heat conduction equation is obtained using the separation of variables method considering thermal boundary conditions. The Chebyshev collocation technique is adopted to compute the numerical values of fundamental frequency for different boundary conditions. The impact of volume fraction index, heterogeneity parameter, density parameter, nodal lines, radii ratio, and thermal boundary conditions on the frequencies of the plate is investigated. An excellent agreement between the results obtained by the present approach and other methods available in the literature validated the authors’ model and technique. Three-dimensional normalized mode shapes with different nodal lines are illustrated for the specified plates.

한국어 낭독과 자유 발화의 운율적 특성*

This study aims to clarify the prosodic differences in speech types by examining the Korean read speech and spontaneous speech in the Korean part of the L2 Korean Speech Corpus (speech corpus for Korean as a foreign language). To this end, the articulation length, articulation speed, pause length and frequency, and the average fundamental frequency values of sentences were set as variables and analyzed via statistical methodologies (<italic>t</italic>-test, correlation analysis, and regression analysis). The results found that read speech and spontaneous speech were structurally different in the form of prosodic phrases constituting each sentence and that the prosodic elements differentiating each speech type were articulation length, pause length, and pause frequency. The statistical results show that the correlation between articulation speed and articulation length was highest in read speech, explaining that the longer a given sentence is, the faster the speaker speaks. In spontaneous speech, however, the relationship between the articulation length and the pause frequency in a sentence was high. Overall, spontaneous speech produces more pauses because short intonation phrases are continuously built to make a sentence, and as a result, the sentence gets lengthened.

Effects of the Voiced Tongue Trill Technique in Glissandos on the Voice Range Profile of Choir Members: A Preliminary Study

The objective of this study was to verify the immediate effect of the voiced tongue trill technique in ascending and descending glissandos on the voice range profile of choir members. A total of 25 sopranos, mezzo-sopranos, contraltos, tenors, and baritones participated in the study. They were choir members, aged 20 to 45 years, with no voice symptoms, and able to perform the voiced tongue trill technique. Their voice range profile was analyzed before and after performing the ascending and descending technique for 2 and 5 minutes. The maximum fundamental frequency values in the study groups increased after performing the ascending and descending technique for 2 minutes (P=0.001) and 5 minutes (P=0.003). The range in Hz increased after 2 minutes (P=0.010) and 5 minutes (P=0.050) of the ascending technique and after 2 minutes (P=0.001) of the descending technique, and the minimum fundamental frequency mean value suffered interference from the type of technique (ascending/descending). The immediate effects of VTTT in glissandos on the VRP of choir members' considering the two factors: condition and time, in ascending and descending glissandos for 2 and 5 minutes increased the maximum frequency and the range in Hz of choristers. Regarding volume levels results, no difference was found in intensity after applying the technique.

Effect of Varied Tube Phonation in Water Exercises on Nasometric and Electroglottographic parameters: Modification in Terms of Fluid Density and Tube Submerged Depth

Within the scope of semi-occluded vocal tract exercises (SOVTEs), we aimed to examine the effects of four exercise combinations, which involved various fluid densities and tube submersion depths, on acoustic and electroglottographic (EGG) parameters. Four procedures (P) were applied consecutively to 30 female participants with normal voices using different tube submersion depths and fluid densities, including P1 (2 cm, water), P2 (2 cm, nectar), P3 (10 cm, water), and P4 (10 cm, nectar). Nasometric (Nasometer II model 6450) and EGG (Electroglottograph model 6103) measurements were taken before the procedures were initiated (pre-test) and at the end of each procedure. In addition, EGG measurements were taken for each procedure during the application. For all three velar positions (oral passage, oro-nasal passage, nasal passage), the only procedure that caused a significant change compared to the pre-test stage in regard to nasalance score was P2 (2 cm nectar) in common. All other procedures except P1 (2 cm water) significantly increased velar closure compared to pre-test levels. However, when the differences between the exercises were examined, the least velar closure, compared to the other procedures, was obtained after P4 (10 cm nectar). While there was no significant difference between the procedures in the EGG measurements during the exercise, a significantly higher tendency to contact was observed after the procedures with a denser consistency, and an increase in the fundamental frequency (fo) values occurred in the pairwise comparisons of the procedures in the measurements after the exercises. In SOVTEs in which water phonation is performed with a tube, the use of a fluid with a consistency denser than water can be considered a particularly promising approach. In addition, exercises performed with increasing consistencies in 2 cm depth can provide more vocal cord and velopharyngeal port closure by increasing EGG-CQ and nasalance score values. However, more care should be taken while increasing the consistency at a submersion depth of 10 cm.

The Effects of Infilled Walls on Seismic Performance of RC Frame Structures with Eccentrically Placed Open Corridor

In this paper, an RC frame model with infilled walls was built and tested, including by a modal test, percussion test and shaking table test, the prototype of which was a collapsed teaching building with an eccentrically placed open corridor during the Wenchuan Earthquake in Xuankou Middle School. The natural frequency of the model was obtained by microseism testing, and the contribution of the infilled walls with different openings to the lateral stiffness of the model was discussed. In addition, the damping ratio, strain responses and internal force distribution of the columns were analysed by knocking the roof of the RC frame model, and then a shaking table test was conducted to study the seismic performance of the model. The results show that the value of longitudinal fundamental frequency increased from 1.88 Hz to 6.65 Hz, and the transverse one increased from 1.90 Hz to 13.40 Hz. The torsion frequency was increased by 6.65 times compared with that when the wall was not built. Furthermore, the damping ratio of the model was significantly increased after the infilled walls were built. When the floor moves longitudinally, the strain at the end of the columns restrained by semi-high continuous infilled walls is 2–4 times that in the unconstrained columns, and the shear force in the restrained columns is 4–8 times that in the unstrained columns. As a result, plastic hinges would form in the constrained columns; then, the columns would lose their vertical load capacity.

Determination of the Fundamental Lateral Bending Mode Frequency of a Spacecraft from its Static Deflection

The primary structure of a spacecraft that involves the central cylinder is designed to meet a specific value of fundamental lateral mode frequency. Though this frequency can be theoretically estimated by using a finite element model, its experimental verification is only possible when the entire spacecraft is made ready. However, static load tests are done on the primary structure of the spacecraft as soon as the structure is realized. In this work, a methodology to determine the fundamental bending mode frequency of a spacecraft from the deflections measured when the structure alone is subjected to static load tests is developed. An expression relating the fundamental lateral bending mode frequency of a spacecraft, having several masses attached at different locations, and the deflection at its tip is derived. Two spacecraft, one of 3000kg class and the other of 6000kg class are taken as examples. The fundamental lateral frequencies are determined using this methodology. These frequencies are also obtained through resonance search tests. It is shown that the derived expression will be very useful in estimating the fundamental lateral mode frequency of a spacecraft with the help of the measured deflection.

On the static deformation and frequency analysis of functionally graded porous circular beams

Due to the availability of limited literature on functionally graded porous circular beams, the static deformation and free vibration analysis of simply supported functionally graded porous circular beams considering the effects of even and uneven porosities are presented in this paper. The Navier type closed-form solutions are obtained for both static and vibration problems within the framework of the higher-order hyperbolic circular beam theory. The theory considers the effects of transverse shear deformation and rotary inertia. The theory satisfies the transverse shear-stress free boundary conditions at the upper and lower surfaces of the beam. The circular beam is made up of the functionally graded material in which material characteristics vary across the thickness direction using the power-law technique which has been adjusted to approximate the porosity effects with even and uneven distributions. A dynamic version of the virtual work principle is employed to derive the governing differential equations of motion, which are then solved analytically using the Navier solution technique. The non-dimensional values of displacements, stresses, and fundamental frequencies are presented for various values of the power-law index (pi), the radius of curvature (R), porosity volume fraction (α), and type of porosity distribution (even and uneven). The present results are compared in few problems with existing literature and found in good agreement with those. This study also highlights some new results for the reference of future researchers, especially on circular beams.

Static Bending and Vibration Analysis of a Rectangular Functionally Gradient Piezoelectric Plate on an Elastic Foundation

In this paper, a functionally graded piezoelectric plate on an elastic foundation composed of two different piezoelectric materials bonded together in the form of plate is studied, and its static bending and fundamental frequencies are analyzed. First, based on Kirchhoff plate theory and the Hamilton principle, the governing equations and corresponding boundary conditions of the model are derived, and then the equations are discretized and solved by the differential quadrature method (DQM). Finally, the effects of physical parameters such as length-to-height ratio, length-to-width ratio, material graded index, foundation stiffness coefficient, temperature change value and external voltage value on static bending deflection, and fundamental frequency value of the functionally graded piezoelectric plate with four sides simply supported are discussed. The calculated results are in good agreement with those in the literature. The data results show that the increase in the elastic foundation stiffness coefficient will increase the equivalent stiffness of the plate. In the process of work, due to the equivalent pressure value generated by the influence of the external voltage, it will lead to unstable phenomena.

Natural frequency analysis of imperfect FG sandwich plates resting on Winkler-Pasternak foundation

The present research analyzes the natural frequencies of the imperfect functionally graded sandwich plate (FGSP) comprised of porous face sheets made of functionally graded materials (FGMs) and an isotropic homogeneous core resting on the elastic foundation. To accomplish this, the material characteristics of the FGSP are taken to be changed incessantly along the thickness direction based on the volume fraction of constituents expressed by the modified rule of the mixture, which includes porosity volume fraction with three diverse kinds of porosity distribution models. Furthermore, to describe the two-parameter elastic foundation's response on the imperfect FGSP, the medium is supposed to be linear, homogenous, and isotropic, and it has been modelled using the Winkler-Pasternak model. Moreover, in the kinematic relationship of the imperfect FGSP resting on the Winkler-Pasternak foundation, third-order shear deformation theory (TSDT) is used, and the motion equations are set up employing Hamilton's principle. For natural frequency analysis of imperfect FGSPs resting on the Winkler-Pasternak foundation with simply supported edges, an analytical solution is obtained. To verify the current formulation, comprehensive comparisons are performed with the available data. The impacts of the two-parameter elastic foundation, porosity volume fraction, porosity distribution types, lay-up scheme, and side to thickness ratio, on the values of the non-dimensional fundamental natural frequency (NDFNF) of the imperfect FGSPs, are investigated, thoroughly.

Vocal Changes in Different Phases of Menstrual Cycle

Introduction Spectral and cepstral analyses of voice have potential clinical implications and can be used as a quantitative acoustic index to assess vocal function in various phases of the menstrual cycle. However, only a handful of studies have attempted to investigate these measures to document the vocal changes across various phases of the menstrual cycle and the results are not conclusive. Therefore, the study aimed to document the acoustic, spectral, and cepstral parameters of voice across the four phases of the menstrual cycle. Methods Phonation samples were recorded during four phases of the menstrual cycle –menstrual phase, follicular phase, ovulation phase, and luteal phase – from 30 female participants. None of the participants reported any hormone-related problems, presence, or history of any voice problems and had a regular menstrual cycle at least from the past 5 years. All the phonation samples were analyzed, and the acoustic, spectral, and cepstral parameters were extracted. Results Fundamental frequency, H1-H2, and cepstral peak prominence (CPP) values were significantly different across the phases of the menstrual cycle. Across the phases of the menstrual cycle, the fundamental frequency, H1-H2, and the CPP values were optimal during the follicular phase and the deviant values were noted during the luteal phase of the menstrual cycle. Conclusion Future investigations could include the analysis of cepstral and spectral parameters extracted from both the phonation and speech samples that can provide more penetrating and ample in-depth insights into the voice changes across the various phases of the menstrual cycle.

Enhancing the Bending Stiffness of Nanosatellite Composite Panel

The extreme working environment presented in many forms such as inevitable vibrations caused by various sources can lead to problems of the impairment of the nanosatellite functionality and integrity of its structure, as well as weakening the protection of internal components, which may trigger minor structural damage to total failure. To solve these addressed problems in this work, the bending stiffness of square laminated composite panel used in the structure of CubeSat, a version of nanosatellite, has been improved. A literature review for the previous studies and publications related to the current work has been studied. A mathematical equation that describes the stiffness behaviour of the composite panel has been derived based on the classical laminated plate theory (CLPT). The equation of motion (E.O.M) is also derived according to the Euler-Lagrange energy equation of the second kind. For determining the eigenfrequencies and eigenmodes of vibrating panel, Fourier series is used to solve the E.O.M of plate supported with a numerical solution using finite element method (FEM) for verification. The optimisation process is conducted to improve the bending stiffness of the structure, which is indicated by the increased value of first mode fundamental frequency, by finding the optimum stacking sequence for a set of design constraints using Miki Diagram method. The obtained results and conclusion from the addressed problem have been reported at the end of this work presenting the enhanced composite-panel bending stiffness and showed a promising findings that believed to contribute solving problems relevant to structural performance of aerospace structures.

Speaker anonymization by modifying fundamental frequency and x-vector singular value

Speaker anonymization is a method of protecting voice privacy by concealing individual speaker characteristics while preserving linguistic information. The VoicePrivacy Challenge 2020 was initiated to generalize the task of speaker anonymization. In the challenge, two frameworks for speaker anonymization were introduced; in this study, we propose a method of improving the primary framework by modifying the state-of-the-art speaker individuality feature (namely, x-vector) in a neural waveform speech synthesis model. Our proposed method is constructed based on x-vector singular value modification with a clustering model. We also propose a technique of modifying the fundamental frequency and speech duration to enhance the anonymization performance. To evaluate our method, we carried out objective and subjective tests. The overall objective test results show that our proposed method improves the anonymization performance in terms of the speaker verifiability, whereas the subjective evaluation results show improvement in terms of the speaker dissimilarity. The intelligibility and naturalness of the anonymized speech with speech prosody modification were slightly reduced (less than 5% of word error rate) compared to the results obtained by the baseline system.

Dynamic characteristics assessment of the Denis‐Perron dam (SM‐3) based on ambient noise measurements

AbstractStanding at a height of 171 m in a narrow valley, the Denis‐Perron dam is the highest embankment dam in Québec, Canada. Between 1998 and 2002, the structure was equipped with three‐component digital strong‐motion accelerometers. The seismic data recorded during three small earthquakes allowed for the estimation of the fundamental vibration frequency (fn) values of the dam in three directions. As part of the present research study, 10 sets of ambient noise measurements were acquired at the dam using six velocimeters, aiming to evaluate the possible 3D site effects and determine the fn values. The first analyses of these experimental data consisted of processing the individual signals with the simple “reference‐dependent spectral” and “ambient vibration horizontal‐to‐vertical spectral ratio (HVSR)” methods. A more advanced modal analysis combining synchronized measurements led to the establishment of additional higher vibration frequency modes and modal shapes. The consistency between the fn values obtained using the simple methods and those from the advanced modal analysis was noticeable. The seismic data provided an exceptional opportunity to validate the experimental data. A comprehensive analysis was thus conducted to compare the dynamic parameters calculated from the processed experimental data with those resulting from the seismic data and proved the values to be similar. In addition, a numerical modal analysis of the 3D valley‐dam system corroborated the plausibility of the vibration modes obtained from the experimental synchronized ambient noise modal analysis. All of these analyses demonstrate the potential of the ambient noise technique for identifying the dynamic characteristics of large rockfill dams built in narrow valleys, without the need for the costly installation and maintenance of accelerometers in low‐seismicity areas.

Source and Filter Acoustic Measures of Young, Middle-Aged and Elderly Adults for Application in Vowel Synthesis

IntroductionThe output sound has important changes throughout life due to anatomical and physiological modifications in the larynx and vocal tract. Understanding the young adult to the elderly speech acoustic characteristics may assist in the synthesis of representative voices of men and women of different age groups. ObjectiveTo obtain the fundamental frequency (f0), formant frequencies (F1, F2, F3, F4), and bandwidth (B1, B2, B3, B4) values extracted from the sustained vowel /a/ of young, middle-aged, and elderly adults who are Brazilian Portuguese speakers; to present the application of these parameters in vowel synthesis. Study DesignProspective study. MethodsThe acoustic analysis of tokens of the 162 sustained vowel /a/ produced by vocally healthy adults, men, and women, between 18 and 80 years old, was performed. The adults were divided into three groups: young adults (18 to 44 years old); middle-aged adults (45 to 59 years old) and, elderly adults (60 to 80 years old). The f0, F1, F2, F3, F4, B1, B2, B3, B4 were extracted from the audio signals. Their average values were applied to a source-filter mathematical model to perform vowel synthesis in each age group both men and woman. ResultsYoung women had higher f0 than middle-aged and elderly women. Elderly women had lower F1 than middle-aged women. Young women had higher F2 than elderly women. For the men's output sound, the source-filter acoustic measures were statistically equivalent among the age groups. Average values of the f0, F1, F2, F3, F4, B1, and B2 were higher in women. The sound waves distance in signals, the position of formant frequencies and the dimension of the bandwidths visible in spectra of the synthesized sounds represent the average values extracted from the volunteers' emissions for the sustained vowel /a/ in Brazilian Portuguese. ConclusionSustained vowel /a/ produced by women presented different values of f0,F1 and F2 between age groups, which was not observed for men. In addition to the f0 and the formant frequencies, the bandwidths were also different between women and men. The synthetic vowels available represent the acoustic changes found for each sex as a function of age.