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Статті в журналах з теми "Main frequencies"

Автор: Grafiati

Опубліковано: 3 червня 2025

Оновлено: 31 липня 2025

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1

Levy, Yeshayahou, Asaf Modelevsky, Joseph Pismenny, Jens Friedrichs, and Detlev Wulff. "Links between Main Frequencies of Established Rotating Stall and Rotational Frequencies and/or Blade Passing Frequencies." International Journal of Rotating Machinery 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/283930.

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The ratios between the main frequency of rotating stall and rotational frequency may be considered in the form of exact ratios of small natural numbers if the pressure signals in compressors during rotating stall include the rotor rotation frequency component. During rotating stall in compressors with good rotor balancing (with absence of the rotational frequency component in the frequency characteristics of pressure signals), these ratios between the main frequency of rotating stall and rotational frequency are or are not in the form of ratios of small natural numbers. The experimentally rece

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2

Balona, L. A., D. L. Holdsworth, and M. S. Cunha. "High frequencies in TESS A–F main-sequence stars." Monthly Notices of the Royal Astronomical Society 487, no. 2 (2019): 2117–32. http://dx.doi.org/10.1093/mnras/stz1423.

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Abstract The driving mechanism for high-frequency oscillations in some chemically peculiar Ap stars, the rapidly oscillating Ap stars (roAp stars), is not understood. The Transiting Exoplanet Survey Satellite mission (TESS) data provide an ideal opportunity to extend the number of roAp stars that might provide further clues to address this problem. From an examination of over 18 000 stars in TESS sectors 1–7, we have discovered high-frequency pulsations in 14 A–F stars, of which only 3 are classified as Ap stars. In addition to these new discoveries, we discuss the frequencies in nine previous

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3

Ball, Warrick H., Jesper Schou, Laurent Gizon, and João P. C. Marques. "Precise and accurate interpolated stellar oscillation frequencies on the main sequence." Proceedings of the International Astronomical Union 9, S301 (2013): 379–80. http://dx.doi.org/10.1017/s1743921313014646.

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AbstractHigh-quality data from space-based observatories present an opportunity to fit stellar models to observations of individually-identified oscillation frequencies, not just the large and small frequency separations. But such fits require the evaluation of a large number of accurate stellar models, which remains expensive. Here, we show that global-mode oscillation frequencies interpolated in a grid of stellar models are precise and accurate, at least in the neighbourhood of a solar model.

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4

Mousavian, R., and M. Mashhadi Hossainali. "Detection of main tidal frequencies using least squares harmonic estimation method." Journal of Geodetic Science 2, no. 3 (2012): 224–33. http://dx.doi.org/10.2478/v10156-011-0043-6.

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AbstractIn this paper the efficiency of the method of Least Squares Harmonic Estimation (LS-HE) for detecting the main tidal frequencies is investigated. Using this method, the tidal spectrum of the sea level data is evaluated at two tidal stations: Bandar Abbas in south of Iran and Workington on the eastern coast of the UK. The amplitudes of the tidal constituents at these two tidal stations are not the same. Moreover, in contrary to the Workington station, the Bandar Abbas tidal record is not an equispaced time series. Therefore, the analysis of the hourly tidal observations in Bandar Abbas

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5

Sharma, M. K. "A Note on Main Effect Plans." Calcutta Statistical Association Bulletin 47, no. 1-2 (1997): 111–16. http://dx.doi.org/10.1177/0008068319970109.

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Method of construction of main effect plans (saturated and unsaturated) through BIB designs, using necessary and sufficient condition of proportional frequencies, is proposed. Using this condition, we obtain two new plans 216/18 and 225/27 not reported earlier. Utilising these plans, we have obtained two new asymmetrical orthogonal main effect plans.

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6

Gasperini, Paolo, Barbara Lolli, and Gianfranco Vannucci. "Relative frequencies of seismic main shocks after strong shocks in Italy." Geophysical Journal International 207, no. 1 (2016): 150–59. http://dx.doi.org/10.1093/gji/ggw263.

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7

Pshenichnyy, V. V., and A. F. Salnikov. "Vibration Dynamic Characteristics Simulation for Helicopter Main Gear Box Test Bench." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 3 (132) (June 2020): 18–28. http://dx.doi.org/10.18698/0236-3941-2020-3-18-28.

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New elements are usually used in developing promising products, and they are introduced to improve its characteristics. This study objective is aimed at making certain decisions to eliminate or reduce negative effects of design and technological solutions that are being identified only at the bench testing stage. Problem of resonant interactions between bench elements and main gear box units is connected to significant distortion of the product under development dynamic analysis results. Therefore, identifying resonant interaction conditions and obtaining reliable results in the course of deve

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8

Романовский, М. В., and А. И. Солдатов. "ACOUSTIC SIGNALS PROCESSING IN UNAUTHORIZED OPERATION ON THE MAIN PIPELINE." Proceedings in Cybernetics 23, no. 1 (2024): 60–67. http://dx.doi.org/10.35266/1999-7604-2024-1-8.

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The article demonstrates an approach for acoustic signal processing under conditions of unauthorized operation on the main pipeline. A case study included tests that simulated illegal pipeline tie-ins using metal pipe drilling. In the course of the study, acoustic signals were recorded and processed using the Fourier transform method. The fi ndings revealed the apexes of common frequencies for each test. The study aims to advance the protection of long-distance high-priority facilities from illegal actions by detecting any threat based on the common apexes of frequencies recorded during acoust

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9

Grigas, Gintautas, and Anita Juškevičienė. "Letter Frequency Analysis of Lithuanian and Other Languages Using the Latin Alphabet." Coactivity: Philology, Educology 23, no. 2 (2015): 81–91. http://dx.doi.org/10.3846/cpe.2015.271.

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It is important to evaluate specificities of alphabets, particularly the letter frequencies while designing keyboards, analyzing texts, designing games based on alphabets, and doing some text mining. In order to adequately compare lettter frequences of Lithuanian language to other languages in the Internet space, Wikipedia source was selected which content is common to different languages. The method of letter frequency jumps is used. The main attention is paid to the analysis of letter frequencies at the boundary between native letters and foreign letters used in Lithuanian and other language

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10

Fuchs-Hanusch, D., F. Friedl, R. Scheucher, B. Kogseder, and D. Muschalla. "Effect of seasonal climatic variance on water main failure frequencies in moderate climate regions." Water Supply 13, no. 2 (2013): 435–46. http://dx.doi.org/10.2166/ws.2013.033.

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The yearly water main failure frequency is a central performance indicator to describe the structural quality of a water distribution network. Besides age related deterioration, events such as severe climatic conditions or intensified third party construction may cause sudden seasonal increases in failure frequency trends. For the cold regions of Canada and the dry regions of Australia, several studies exist describing the impacts of climatic failure frequencies on water main failure variations. Failure prediction modelling applied to Austrian supply systems have shown that irregularities in o

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11

Orazkhan, B., С. Kuttybekova, A. Baymakhan, and R. Baymakhan. "Criteria truth computer simulation of frequency response curves of the free oscillations hillsides systems." Bulletin of Science and Practice, no. 11 (November 14, 2017): 243–50. https://doi.org/10.5281/zenodo.1048459.

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The information database on the accuracy of the computed values of the frequency characteristics of free oscillations of a triangular-shaped dam rigidly fixed to a rock foundation decided by different authors is analyzed. As a result of the analysis of the influence of the finite element forms, a special criterion is proposed that allows to assign a minimum amount of the design of the target nodal masses. The results of a finite element calculation for finding the frequency characteristics of a complex large-scale object-consisting of mountain slope systems in the interrelation between themsel

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12

Balona, L. A. "Rapidly oscillating TESS A–F main-sequence stars: are the roAp stars a distinct class?" Monthly Notices of the Royal Astronomical Society 510, no. 4 (2022): 5743–59. http://dx.doi.org/10.1093/mnras/stac011.

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ABSTRACT From sector 1–44 TESS observations, 19 new rapidly oscillating Ap (roAp) stars, 103 ostensibly non-peculiar stars with roAp-like frequencies, and 617 δ Scuti stars with independent frequencies typical of roAp stars were found. Examination of all chemically peculiar stars observed by TESS resulted in the discovery of 199 Ap stars that pulsate as δ Sct or γ Dor variables. The fraction of pulsating Ap stars is the same as the fraction of pulsating chemically normal stars. There is no distinct separation in frequency or radial order between chemically peculiar δ Sct stars and roAp stars.

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13

YU, XUEPING, ZHILIANG CAO, and RUSHAN HAN. "A MAIN DIMER OF FULLERENES: C118." Modern Physics Letters B 10, no. 28 (1996): 1423–30. http://dx.doi.org/10.1142/s0217984996001607.

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A photopolymerization of C 60 molecules occurs in the irradiation of oxygen-free C 60 film with visible or ultraviolet light. Results from mass spectroscopy indicate that C 118 is the principal dimer among the dimers around C 120. Three most possible isomers of C 118 are presented and studied. Geometries are optimized with tight-binding method and two techniques. Vibrational modes are also obtained. Their stretching frequencies are from 106 cm −1 to 133 cm −1, which are consistent with the experimental value 116 cm −1.

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14

Moerman, A., B. A. Wols, and R. Diemel. "The effects of traffic loads on drinking water main failure frequencies in the Netherlands." Water Practice and Technology 11, no. 3 (2016): 524–30. http://dx.doi.org/10.2166/wpt.2016.057.

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Understanding pipe failure is essential for effective asset management. Buried drinking water pipes are exposed to several types of external loads, e.g. soil weight, loads due to soil settling differences and traffic loads. The hypothesis that traffic loads positively affects the number of failures was statistically tested. For three out of four studied water companies significant higher failure frequencies than average were found at road crossings. Frequencies equal to average were found for pipes which are installed under other road sections. Frequencies higher than average–but not statistic

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15

Appourchaux, T., W. J. Chaplin, R. A. García, et al. "Oscillation mode frequencies of 61 main-sequence and subgiant stars observed byKepler." Astronomy & Astrophysics 543 (June 27, 2012): A54. http://dx.doi.org/10.1051/0004-6361/201218948.

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16

Kuzin, P. I., E. I. Kuzina, A. P. Boyko, D. A. Starikov, and E. N. Chapurin. "ACCURACY OF DETERMINATION OF LINEAR SPECTRAL FREQUENCIES." Vestnik komp'iuternykh i informatsionnykh tekhnologii, no. 211 (January 2022): 3–10. http://dx.doi.org/10.14489/vkit.2022.01.pp.003-010.

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The article describes the basic idea of coding a speech signal by the method of linear prediction (Linear Predictive Coding – LPC), which consists in the fact that instead of the parameters of the speech signal, the encoded parameters of a certain filter are transmitted over the communication line, which is, in a sense, an equivalent of the human vocal tract, as well as parameters of the excitation signal of this filter: tone or noise. The essence of the parameters of the synthesizing filter – linear prediction coefficients (LP), calculated in the process of frame-by-frame adaptive filtering –

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17

Balona, Luis A. "Pulsation in Hot Main-Sequence Stars: Comparison of Observations with Models." Universe 10, no. 12 (2024): 437. http://dx.doi.org/10.3390/universe10120437.

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The locations of hot pulsating variables in the H–R diagram are found using the effective temperatures derived from spectroscopic analysis and luminosities from Gaia parallaxes. Frequency peaks extracted from TESS photometry were used to compare with model predictions. A large number of stars with pulsation frequencies similar to δ Scuti variables were found between the predicted δ Scuti and β Cephei instability regions, contrary to the models. These Maia variables cannot be explained by rapid rotation. There is a serious mismatch between the observed and predicted frequencies for stars within

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18

Braude, S. Ya, A. A. Konovalenko, and A. V. Megn. "The Universe at Very Low Radio Frequencies." Symposium - International Astronomical Union 199 (2002): 490–91. http://dx.doi.org/10.1017/s0074180900169633.

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19

Piankitrungreang, Pimolkan, Kantawatchr Chaiprabha, Worathris Chungsangsatiporn, Chanat Ratanasumawong, Peemdej Chancharoen, and Ratchatin Chancharoen. "Acoustic-Based Machine Main State Monitoring for High-Speed CNC Drilling." Machines 13, no. 5 (2025): 372. https://doi.org/10.3390/machines13050372.

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This paper introduces an acoustic-based monitoring system for high-speed CNC drilling, aimed at optimizing processes and enabling real-time machine state detection. High-fidelity acoustic sensors capture sound signals during drilling operations, allowing the identification of critical events such as tool engagement, material breakthrough, and tool withdrawal. Advanced signal processing techniques, including spectrogram analysis and Fast Fourier Transform, extract dominant frequencies and acoustic patterns, while machine learning algorithms like DBSCAN clustering classify operational states suc

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20

Daszyńska-Daszkiewicz, Jadwiga, and Przemysław Walczak. "Complex asteroseismology of the B-type main sequence pulsators." Proceedings of the International Astronomical Union 5, H15 (2009): 364–65. http://dx.doi.org/10.1017/s1743921310009828.

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AbstractWe present examples of an extended asteroseismic modelling in which we aim at fitting not only pulsational frequencies but also certain complex parameter related to each frequency. This kind of studies, called complex asteroseismology, has been successfully applied to a few main sequence B-type pulsators and provided, in particular, plausible constraints on stellar opacities. Here, we briefly describe our results for three early B-type stars.

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21

B., U. Agbo, A. T. Ebuehi O., and A. Osuntoki A. "Ethnic Origin of Crime Scene Evidential Materials Determination in Three Main Ethno-linguistic Population Groups in Nigeria." Annual Research & Review in Biology 12, no. 4 (2017): 1–8. https://doi.org/10.9734/ARRB/2017/32783.

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DNA analysis using autosomal short tandem repeat (microsatellite) polymorphism is a useful tool for forensic purposes, such as individual identification, stain analysis and paternity testing. Analyses of such materials are carried out by the comparison of profiles from questioned samples or crime scene with those from suspects or victims or from database. In some instances, the profiles generated will neither match that from suspects nor the database. The objective of the current study is to identify population specific markers that will show distinct genetic variability among the three main e

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22

Panova, N. V., and E. A. Spiridonov. "Stress-strain State and Vibration Frequencies of Blades of the Main Mine Fan Impeller." Open Journal of Applied Sciences 03, no. 02 (2013): 56–60. http://dx.doi.org/10.4236/ojapps.2013.32b011.

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23

Thomas, Alexandra E. L., William J. Chaplin, Sarbani Basu, Ben Rendle, Guy Davies, and Andrea Miglio. "Impact of magnetic activity on inferred stellar properties of main-sequence Sun-like stars." Monthly Notices of the Royal Astronomical Society 502, no. 4 (2021): 5808–20. http://dx.doi.org/10.1093/mnras/stab354.

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ABSTRACT The oscillation frequencies observed in Sun-like stars are susceptible to being shifted by magnetic activity effects. The measured shifts depend on a complex relationship involving the mode type, the field strength, and spatial distribution of activity, as well as the inclination angle of the star. Evidence of these shifts is also present in frequency separation ratios that are often used when inferring global properties of stars in order to avoid surface effects. However, one assumption when using frequency ratios for this purpose is that there are no near-surface perturbations that

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24

Bugnet, L., V. Prat, S. Mathis, et al. "Magnetic signatures on mixed-mode frequencies." Astronomy & Astrophysics 650 (June 2021): A53. http://dx.doi.org/10.1051/0004-6361/202039159.

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Context. The discovery of moderate differential rotation between the core and the envelope of evolved solar-like stars could be the signature of a strong magnetic field trapped inside the radiative interior. The population of intermediate-mass red giants presenting surprisingly low-amplitude mixed modes (i.e. oscillation modes that behave as acoustic modes in their external envelope and as gravity modes in their core) could also arise from the effect of an internal magnetic field. Indeed, stars more massive than about 1.1 solar masses are known to develop a convective core during their main se

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25

Zhong, Bin, Shengdun Zhao, Renfeng Zhao, and Jiean Liao. "Numerical and experimental investigation on the influence of main motor rotational frequency in fine-cropping." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 3 (2013): 514–24. http://dx.doi.org/10.1177/0954406213486592.

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The bar fine-cropping, the first and one of the most important metal-forming procedure, separates the work-piece into accurate products and billets. The aim of this article is to investigate the influence of different main motor rotational frequencies on a new fine-cropping system. Five different rotational frequencies are applied to both the numerical simulations and the fine-cropping experiments. The numerical and experimental results show that good agreement is achieved by combining the average stress triaxiality under different stress states: the equivalent plastic strain, the fatigue-crac

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26

Nie, Zhi Feng, and Xing Long Li. "Modal Analysis of Coal Preparation Plant Based on ANSYS." Applied Mechanics and Materials 353-356 (August 2013): 3541–44. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.3541.

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Finite element model of the main building of Zhaoguan coal preparation plant was established and its modal analysis was carried out based on ANSYS. The front six orders natural frequencies and modal shapes were calculated and the vibration characteristics were carried out. Results of modal analysis showed that the front six orders natural frequencies of the main building are between 1.7252 Hz to 5.1332Hz, which are far less than the working frequency of vibrating screen 15 Hz, so that the resonance phenomenon would not exist in the main building of the coal preparation plant.

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27

Cahyono, Arif, Eka Fadilah, and Lailatul Musyarofah. "Analysis of speech acts in Charles Dickens' Great Expectations: A politeness language analysis." Jurnal CULTURE (Culture, Language, and Literature Review) 10, no. 1 (2023): 30–39. http://dx.doi.org/10.53873/culture.v10i1.501.

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This research studies about politeness strategies in Charles Dickens Great Expectations. The writer analyze of Speech Acts in Charles Dickens' Great Expectations: A Politeness Language Analysis. The purposes of the research were to know the kinds of politeness strategies which used by the main characters in directive utterance and the politeness strategies of directive act in title. The data of this research was Charles Dickens' Great Expectations. This research was done by descriptive qualitative method. The research findings show that there were 2 types of politeness strategies. Based on the

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28

Pu, Weiming, Kewei Feng, Xiaoping Wang, Zhennan Liang, Xinliang Chen, and Quanhua Liu. "Enhanced Mainlobe Jamming Suppression in Distributed Array Radar via Joint Optimization of Radar Positions and Subpulse Frequencies." Remote Sensing 17, no. 14 (2025): 2423. https://doi.org/10.3390/rs17142423.

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This study presents a joint optimization framework for radar positions and subpulse carrier frequencies to address mainlobe jamming suppression in a distributed array radar system with one main and multiple auxiliary radars. Accounting for gain and aperture differences between the main and auxiliary radars, the grating lobe effect on jamming suppression performance is analyzed. Unlike conventional sparse array design approaches, this work introduces an architecture leveraging subpulses at distinct carrier frequencies to enhance grating lobe suppression and jamming suppression. A specific joint

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29

Suleymanova, Svetlana A., and V. D. Pugachev. "A Decade of Low Frequency Pulsar Polarimetry at PRAO: a Review of the Main Results." International Astronomical Union Colloquium 177 (2000): 201–4. http://dx.doi.org/10.1017/s0252921100059479.

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AbstractThe main results of the linear polarization measurements of pulsars done at the lowest radio frequencies 40, 60 and 103 MHz are summarized in this paper. We have analyzed 35 integrated polarization profiles and 20 statistical distribution displays and compared them with published high frequency results.

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30

Yang, Wuming. "ESTIMATING THE RADIUS OF THE CONVECTIVE CORE OF MAIN-SEQUENCE STARS FROM OBSERVED OSCILLATION FREQUENCIES." Astrophysical Journal 829, no. 2 (2016): 68. http://dx.doi.org/10.3847/0004-637x/829/2/68.

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31

Srivastava, J. N., and S. Ghosh. "On nonorthogonality and nonoptimality of Addelman's main-effect plans satisfying the condition of proportional frequencies." Statistics & Probability Letters 26, no. 1 (1996): 51–60. http://dx.doi.org/10.1016/0167-7152(94)00251-7.

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32

Tsaliev, T. A., and A. O. Vakarchuk. "CHARACTERISTICS OF VIBRATOR ARRAYS DIRECTIVITY ON HARMONICS OF MAIN FREQUENCY." Proceedings of the O.S. Popov ОNAT 1, no. 2 (2020): 40–49. http://dx.doi.org/10.33243/2518-7139-2020-1-2-40-49.

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Antenna patterns representing dependences of the directivity factor (DF) on angular coordinates for arrays formed from Yagi-Uda aerials are considered and discussed. The results of computer modelling are based on the decision of integral equations by the method of moments. Patterns that represent dependences of the coefficient of the directivity factor (DF) for an array and her elements from angular coordinates are counted on fundamental frequency and four harmonics. The data obtained confirmed the validity of the assumptions that the directivity properties of vibrator antenna arrays can signi

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33

Qui, Hua, and Yang Enhui. "Effect of Thickness, Density and Cavity Depth on the Sound Absorption Properties of Wool Boards." Autex Research Journal 18, no. 2 (2018): 203–8. http://dx.doi.org/10.1515/aut-2017-0020.

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Abstract A novel wool absorption board was prepared by using a traditional non-woven technique with coarse wools as the main raw material mixed with heat binding fibers. By using the transfer-function method and standing wave tube method, the sound absorption properties of wool boards in a frequency range of 250-6300 Hz were studied by changing the thickness, density, and cavity depth. Results indicated that wool boards exhibited excellent sound absorption properties, which at high frequencies were better than that at low frequencies. With increasing thickness, the sound absorption coefficient

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34

Vijayalakshmi, N., Dr P.Sekhar, and Dr G.Mokesh Rayalu. "Estimation of Gene Frequencies in Clinical Research." International Journal of Engineering & Technology 7, no. 4.10 (2018): 508. http://dx.doi.org/10.14419/ijet.v7i4.10.21213.

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Biometrics is a branch of statistics in which various mathematical and statistical techniques can be applied to biological research problems. These are two main areas of specialization of Biometry namely, Bioassays and Quantitative Genetics. Genetics concerns with Heredity and variation. Quantitative Genetics is concerned with the inheritances of quantitative differences between individuals.The essence of Quantitative Genetics is to estimate the genetic parameters such as Gene frequencies, segregation Ratios, Recombination of Genes and so on. Among them, the estimation of Gene Frequencies in t

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35

Harger, Arthur, Lucas H. S. Carmo, Alfredo Gay Neto, Alexandre N. Simos, Guilherme R. Franzini, and Guilherme Henrique Rossi Vieira. "Modal Analysis of 15 MW Semi-Submersible Floating Wind Turbine: Investigation on the Main Influences in Natural Vibration." Wind 3, no. 4 (2023): 548–66. http://dx.doi.org/10.3390/wind3040031.

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One of the sources of sustainable energy with great, still untapped potential is wind power. One way to harness such potential is to develop technology for offshore use, more specifically at high depths with floating turbines. It is always critical that their structural designs guarantee that their natural frequencies of vibration do not match the frequencies of the most important oscillatory loads to which they will be subjected. This avoids resonance and its excessive undesired oscillatory responses. Based on that, a 3D finite element model of a 15 MW semi-submersible floating offshore wind

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36

Ancans, G., A. Stafecka, V. Bobrovs, A. Ancans, and J. Caiko. "Analysis of Characteristics and Requirements for 5G Mobile Communication Systems." Latvian Journal of Physics and Technical Sciences 54, no. 4 (2017): 69–78. http://dx.doi.org/10.1515/lpts-2017-0028.

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Abstract One of the main objectives of the fifth generation (5G) mobile communication systems, also known as IMT-2020, is to increase the current data rates up to several gigabits per second (Gbit/s) or even up to 10 Gbit/s and higher. One of the possibilities to consider is the use of higher frequencies in order to enlarge the available bandwidth. Wider bandwidth is necessary to achieve much higher data rates. It should be noted that wireless broadband transmission technologies require frequencies for their development. The main goal of the research is to investigate the characteristics and r

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Semaan, T., A. M. Hubert, J. Zorec, et al. "Study of a sample of faint Be stars in the exofield of CoRoT." Astronomy & Astrophysics 613 (May 2018): A70. http://dx.doi.org/10.1051/0004-6361/201629243.

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Context. The class of Be stars are the epitome of rapid rotators in the main sequence. These stars are privileged candidates for studying the incidence of rotation on the stellar internal structure and on non-radial pulsations. Pulsations are considered possible mechanisms to trigger mass-ejection phenomena required to build up the circumstellar disks of Be stars. Aims. Time series analyses of the light curves of 15 faint Be stars observed with the CoRoT satellite were performed to obtain the distribution of non-radial pulsation (NRP) frequencies in their power spectra at epochs with and witho

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38

Agüero-Valdez, Diana, Alain González-Sánchez, María Teresa Rodríguez-Hernández, et al. "Ultrasound-Assisted Melt Extrusion of Polymers with the Main Harmonics of 10–60 kHz." Fluids 10, no. 6 (2025): 150. https://doi.org/10.3390/fluids10060150.

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Using a digital oscilloscope, the main harmonics resulting from the application of different frequencies and power levels of ultrasonic waves during the polymer extrusion process were identified. The primary harmonics are located between 10 and 60 kHz and exhibit unique characteristics, such as shape, crest, and trough, the latter being associated with voltage and current. The crest-to-trough distance (height) observed during processing at 34 kHz and 375 W shows the highest value, which correlates with the highest melt flow index and the lowest apparent viscosity. It is well known that the app

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39

KOMAROV, P. V., and D. S. POTEKHIN. "INVESTIGATION OF A DYNAMICALLY CHANGING SIGNAL USING WAVELET TRANSFORMATIONS." Computational nanotechnology 11, no. 3 (2024): 34–42. http://dx.doi.org/10.33693/2313-223x-2024-11-3-34-42.

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In the presented work, a wavelet analysis of the patient’s electroencephalogram was performed, followed by the construction of a scalogram. This approach made it possible to identify the frequency components of the electroencephalogram and conduct a comprehensive analysis of them. The obtained results can be used to monitor the state of the patient’s brain activity. The main purpose of the study is to analyze and filter the signal to determine the main composite frequencies of the electroencephalographic signal, on the basis of which it is possible to determine the state of brain activity at c

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40

Dulinska, Joanna M., and Pawel Boron. "Changes of Natural Frequencies of Industrial Steel Hall due to Simplifications of Numerical Model." Advanced Materials Research 790 (September 2013): 16–20. http://dx.doi.org/10.4028/www.scientific.net/amr.790.16.

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The paper presents changes of natural frequencies of industrial steel hall due to simplifications or changes of numerical model. Firstly, the natural frequencies were calculated for basic Variant A of the numerical model of the steel hall which consisted of the main frames, footings, roof purlins and girts. In this Variant columns were fixed at bases, both purlins and girts were rigidly connected to main frames and designed as continuous beams. Then, in Variant B of the model columns were pinned at bases. Next, in Variant C different types of connections (semi-flexible joints) of roof purlins

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Modebadze, Iuri, and Vakhtang Abuladze. "Calculation of the Parasitic Frequencies Generated in the Optical Fiber Using the LabVIEW Program in Case of the Initial Five Waves." Works of Georgian Technical University, no. 2(528) (May 29, 2023): 27–34. http://dx.doi.org/10.36073/1512-0996-2023-2-27-34.

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The calculation of the parasitic frequencies generated by the four-wave mixing method during the passage of the five main frequencies in the optical fiber using the LabVIEW program is discussed. The virtual tool used for this is built using mathematical expressions and a program for calculating the approximate values of parasitic frequencies given in the article. It counts the number of parasitic frequencies and calculates their corresponding values that will be placed in the 185-189 terahertz frequency range of the first five frequencies. An algorithm has been compiled for the construction of

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42

Klaassen, T., M. Teder, M. Viikmaa та A. Metspalu. "Neonatal screening for the cystic fibrosis main mutation ΔF508 in Estonia". Journal of Medical Screening 5, № 1 (1998): 16–19. http://dx.doi.org/10.1136/jms.5.1.16.

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In this pilot study the frequency of ΔF508 mutation carriers, their geographic distribution, and the prevalence of cystic fibrosis (CF) in Estonia were investigated. During the screening programme 7396 newborns were tested for ΔF508 mutation and 88 were found to carry this deletion. The mean frequency of ΔF508 mutation carriers in Estonia was thus estimated as 1 out of 84 live births. In eight separate districts of Estonia the heterozygote frequencies differed significantly (p=0.0369), with the highest incidence (1:36) on the Baltic Sea islands and western coastal region and with the lowest in

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43

Zhou, Si Zhu, Xin Long Chen, Jian Ping Li, Jun Xu, and Yong Wang. "Vibration Testing and Analysis of ZJ70D Rig Base." Applied Mechanics and Materials 318 (May 2013): 11–14. http://dx.doi.org/10.4028/www.scientific.net/amm.318.11.

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In order to obtain the first 4 natural frequencies and vibration modals of ZJ70D drilling rig base. The experimental modal of the base is measured under the environment of uTekMa modal test system. Testing result shows it is identical to actual vibration condition. Comparing to the power frequency of engine, reducer, etc, it is found their working frequencies and frequency multiplications approach the drilling rig base natural frequencies, which are the main reason of drilling rig base vibration.

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Nizom, Ermatov. "HYGIENE ASSESSMENT OF NOISE LEVELS IN MAIN WORKPLACES IN THE PLASTICS INDUSTRY." Community Practitioner 20, no. 08 (2023): 171–75. https://doi.org/10.5281/zenodo.8255614.

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<strong>Abstract</strong> Labour of workers of the main occupations of plastic products manufacturing is connected with complex influence of harmful factors, of which one of the leading ones is mechanical, inconstant, broadband noise with predominance of high and middle frequencies. At frequency of 500 Hz the high level was set at sawing operation 83,6±1,1 dB, at frequency of 1000 Hz - 80,8±0,37 dB, that on the average exceeds by 5 dB the normative value. Noise with predominance of high frequencies of 2000 and 4000 Hz was also determined during sawing in the chipper, respectively

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Segun, Adewumi Adebayo, Eleyele Dolapo Emmanuel, Alagbe Atilade George, and Azeez Ibraheem Abiodun. "DESIGN, SIMULATION AND PERFORMANCE EVALUATION OF HELICAL ANTENNA FOR 4G AND 5G MOBILE NETWORKS COMPLIANCE." Acta Electronica Malaysia 8, no. 2 (2024): 39–44. https://doi.org/10.26480/aem.02.2024.39.44.

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The 5G cellular network aims to address bandwidth needs due to the large number of subscribers worldwide. However, higher-bandwidth antennas are needed to integrate into the design. Helical antennas offer design simplicity, gain, and wider bandwidth, but their radiation pattern narrows bandwidth as diameter and turn increase. This paper aims to develop and evaluate the performance of helical antennas at different dimensions and turns for 4G and 5G network frequency applications. The study used MATLAB 2021a to design and simulate helical antennas with various turns. Parameters like width, spaci

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Minowa, Chikahiro, Djamshid Kaniev, and Akmal Rustamov. "Vibration measurement of KIUT building by MEMS accelerometer." E3S Web of Conferences 401 (2023): 05031. http://dx.doi.org/10.1051/e3sconf/202340105031.

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This paper describes the measurements of structure small vibration in buildings of Yeoju Technical Institute in Tashkent (YTIT) in the use of MEMS accelerometer. The natural frequencies of main 6-story building were about 1.55Hz in both directions. In additions, the frequencies were measured for 10-story curve building under construction.

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47

Balona, L. A., and D. Ozuyar. "Pulsation among TESS A and B stars and the Maia variables." Monthly Notices of the Royal Astronomical Society 493, no. 4 (2020): 5871–79. http://dx.doi.org/10.1093/mnras/staa670.

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ABSTRACT Classification of over 50 000 TESS stars in sectors 1–18 has resulted in the detection of 766 pulsating main-sequence B stars as well as over 5000 δ Scuti, 2300 γ Doradus, and 114 roAp candidates. Whereas it has been assumed that high-frequency pulsations among B-type main-sequence stars are confined to the early B-type β Cephei stars, the observations indicate that high frequencies are to be found over the whole B-star range, eventually merging with δ Scuti stars. The cool B stars pulsating in high frequencies are called Maia variables. It is shown that Maia variables are not rapidly

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Dolmatov, E. N., S. Y. Ilin, and V. V. Eliferov. "Air Injection as a Solution to the Problem for Reducing High-Frequency Acoustic Noise in Some Operating Modes of Francis Hydro Turbines." E3S Web of Conferences 320 (2021): 04005. http://dx.doi.org/10.1051/e3sconf/202132004005.

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During operation of Francis hydro turbines at the regimes of 70–95 % of Nrated, high-frequency acoustic phenomena (noise) were recorded. In order to study and identify the causes of these phenomena, special field tests were conducted. The main objectives of the tests were: determination of the main frequencies of acoustic phenomena, comparison with natural frequencies of the turbine water passages elements and the search for solutions to reduce acoustic phenomena. During the tests, the natural frequencies of the elements of turbine water path were investigated. Several methods of air injection

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49

Morales-Sánchez, Gerardo, Antonio Collazo, and Jesús Doval-Gandoy. "Influence of the Process Parameters on the Quality and Efficiency of the Resistance Spot Welding Process of Advanced High-Strength Complex-Phase Steels." Metals 11, no. 10 (2021): 1545. http://dx.doi.org/10.3390/met11101545.

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In this study, the effects of electrical characteristics of an inverter combined with main welding parameters on the resistance spot weldability of advanced high strength steels (AHSS) CP1000 is investigated. The main welding parameters, current and time, were varied. The effects on the geometry and microstructure of the weld spot, the diameter of the weld pad, the hardness, the shear strength, and the efficiency of the process were studied, and the results were compared for two switching frequencies of the medium frequency converter. Furthermore, the weldability lobes were obtained as a funct

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50

Rebelo, Glória, and António R. Almeida. "Accidents at work – a qualitative study on the main procedural vicissitudes in Portuguese case law." International Journal on Working Conditions, no. 28 (June 2, 2025): 109–25. https://doi.org/10.5281/zenodo.15575279.

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<u>Abstract</u>: The issue of accidents at work linked to the protection of occupational safety and health has been an international political concern for decades. Despite various advances, statistics on accidents at work (fatal and non-fatal) still show a relatively high incidence in some EU countries, particularly in Portugal. Occupational safety and health issues are at the centre of European social policies and national public policies. The aim of this article is to identify, based on an analysis of Portuguese case law, the most frequent issues relating to accidents at work in the courts.

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