Estimation of Damping Correction Factors Using Duration Defined by the Standard Deviation of Phase Difference

The damping correction factors (DCFs) to convert the 5% damping acceleration response spectra to those for other damping levels are computed for the records of 13 Japanese earthquakes. Their correlation with the standard deviation of phase difference ( σ) is also investigated in ten frequency bands. The σ-DCF relations obtained are found to be very similar across the different types of earthquakes. Further, regression analysis suggests that for damping ratios of 1% and 2%, with the increase in σ, the DCFs increase in low-frequency bands (up to 4–5 Hz), whereas they decrease in higher frequency bands. On the other hand, for damping ratios of more than 5%, with the increase in σ, the DCFs decrease in low-frequency bands (up to 1 Hz), whereas the opposite tendency is observed in higher frequency ranges. This research also discusses the applicability of the σ-DCF relations to design ground motion simulation.

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Comparison of the Dynamic and Static Corner Frequencies in Ground Motion Simulation: Cases Study of Jiuzhaigou Earthquake and Northridge Earthquake

Frontiers in Earth Science ◽

10.3389/feart.2021.813089 ◽

2022 ◽

Vol 9 ◽

Author(s):

Pengfei Dang ◽

Qifang Liu ◽

Linjian Ji

Keyword(s):

Response Spectra ◽

Corner Frequency ◽

Northridge Earthquake ◽

Acceleration Response ◽

Jiuzhaigou Earthquake ◽

Frequency Model ◽

Ground Motion Simulation ◽

Finite Fault ◽

Finite Fault Method ◽

Dynamic Corner Frequency

By using the stochastic finite-fault method based on static corner frequency (Model 1) and dynamic corner frequency (Model 2), we calculate the far-field received energy (FRE) and acceleration response spectra (SA) and then compare it with the observed SA. The results show that FRE obtained by the two models depends on the subfault size regardless of high-frequency scaling factor (HSF). Considering the HSF, the results obtained by Model 1 and Model 2 are found to be consistent. Then, similar conclusion was obtained from the Northridge earthquake. Finally, we analyzed the reasons and proposed the areas that need to be improved.

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THE INFLUENCE OF ROOM ACOUSTIC PARAMETERS ON THE PERCEPTION OF ROOM CHARACTERISTICS

Akustika ◽

10.36336/akustika20203728 ◽

2020 ◽

pp. 28

Author(s):

Alicja Jasińska ◽

Maurycy Kin

Keyword(s):

Standard Deviation ◽

Subjective Evaluation ◽

Strength Parameter ◽

Acoustic Parameters ◽

Sound Sources ◽

Different Types

The article presents the possibility of identification of rooms on the basis of binaural perception. Results of subjective evaluation were compared with the values of sound strength, G. A previously unknown sound term was introduced: the strength of spatial impression as the inverse of standard deviation of the results obtained. It turned out that the results presenting the sound strength parameter can be correlated with the subjective evaluation of the spatial impression, which is the size of the room. It can be helpful in the process of room identification, probably due to the reverberation impression in the room. Authors plan to continue the study with more rooms and different types of sound sources.

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Spillovers of Stock Markets among the BRICS: New Evidence in Time and Frequency Domains before the Outbreak of COVID-19 Pandemic

Journal of Risk and Financial Management ◽

10.3390/jrfm14030112 ◽

2021 ◽

Vol 14 (3) ◽

pp. 112

Author(s):

Kai Shi

Keyword(s):

Stock Market ◽

Frequency Band ◽

Stock Markets ◽

Emerging Market ◽

Low Frequency ◽

Systematic Risk ◽

Error Variance ◽

Frequency Bands ◽

Volatility Spillovers ◽

Risk Sources

We attempted to comprehensively decode the connectedness among the abbreviation of five emerging market countries (BRICS) stock markets between 1 August 2002 and 31 December 2019 not only in time domain but also in frequency domain. A continuously varying spillover index based on forecasting error variance decomposition within a generalized abbreviation of vector-autoregression (VAR) framework was computed. With the help of spectral representation, heterogeneous frequency responses to shocks were separated into frequency-specific spillovers in five different frequency bands to reveal differentiated linkages among BRICS markets. Rolling sample analyses were introduced to allow for multiple changes during the sample period. It is found that return spillovers dominated by the high frequency band (within 1 week) part declined with the drop of frequencies, while volatility spillovers dominated by the low frequency band (above 1 quarter) part grew with the decline in frequencies; the dynamics of spillovers were influenced by crucial systematic risk events, and some similarities implied in the spillover dynamics in different frequency bands were found. From the perspective of identifying systematic risk sources, China’s stock market and Russia’s stock market, respectively, played an influential role for return spillover and volatility spillover across BRICS markets.

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Electrically small dual-band substrate-integrated-waveguide antenna with fixed low-frequency and tunable high-frequency bands

IEICE Electronics Express ◽

10.1587/elex.11.20140007 ◽

2014 ◽

Vol 11 (5) ◽

pp. 20140007-20140007 ◽

Cited By ~ 3

Author(s):

Hyunseong Kang ◽

Sungjoon Lim

Keyword(s):

High Frequency ◽

Low Frequency ◽

Dual Band ◽

Substrate Integrated Waveguide ◽

Frequency Bands

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Ground Attenuation Factor Based on Measurements

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-2405 ◽

2021 ◽

Vol 263 (3) ◽

pp. 3436-3447

Author(s):

Dan Lin ◽

Andrew Eng

Keyword(s):

Near Field ◽

Attenuation Factor ◽

Measurement Data ◽

Low Frequency ◽

Sound Sources ◽

Frequency Sound ◽

Sound Levels ◽

Different Types ◽

Noise Measurements ◽

Field Sound

Assumptions made on the ground types between sound sources and receivers can significantly impact the accuracy of environmental outdoor noise prediction. A guideline is provided in ISO 9613-2 and the value of ground factor ranges from 0 to 1, depending on the coverage of porous ground. For example, a ground absorption factor of 1 is suggested for grass ground covers. However, it is unclear if the suggested values are validated. The purpose of this study is to determine the sound absorption of different types of ground by measurements. Field noise measurements were made using an omnidirectional loudspeaker and two microphones on three different types of ground in a quiet neighborhood. One microphone was located 3ft from the loudspeaker to record near field sound levels in 1/3 and 1 octave bands every second. The other microphone was located a few hundred feet away to record far field sound in the same fashion as the near field microphone. The types of ground tested were concrete, grass, and grass with trees. Based on the measurement data, it was found that grass and trees absorb high frequency sound well and a ground factor of 1 may be used for 500Hz and up when using ISO 9613-2 methodology. However, at lower frequencies (125 Hz octave band and below), grassy ground reflects sound the same as concrete surfaces. Trees absorb more low frequency sound than grass, but less than ISO 9613-2 suggested.

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Study of the significance of the ph of the substrate of the biogas installation during treating it with a low-frequency electromagnetic field

Energy and automation ◽

10.31548/energiya2021.05.106 ◽

2021 ◽

pp. 106-114

Author(s):

M.M. Zablodsky ◽

◽

P.B. Klendiy ◽

O. P. Dudar ◽

◽

...

Keyword(s):

Electromagnetic Field ◽

Electromagnetic Induction ◽

Ph Value ◽

Low Frequency ◽

Decisive Role ◽

Methane Fermentation ◽

Different Types ◽

Substrate Ph ◽

Fermentation Substrate ◽

Industrial Frequency

The article considers the issue of studying the value of pH, substrate in the process of methane fermentation in the mesophilic regime and the influence of the electromagnetic field of industrial frequency. The aim is to investigate the influence of electromagnetic fields on the pH value of the substrate during fermentation. Different types of microorganisms are involved in the process of methanogenesis, and the decisive role in it is played by methane-forming archaea, which are most sensitive to pH and should be in the range of 6.5 - 8. Therefore, it is necessary to check the effect of low frequency electromagnetic field on substrate pH. The study was performed for 25 days on two substrates, one of which was exposed to a low-frequency electromagnetic field with an electromagnetic induction of 3.5 mT. The research results show that the pH value of the substrate exposed to the electromagnetic field during the methane fermentation process was within acceptable limits, and the second substrate decreased, that is, it was acidified. Key words: methane fermentation, substrate, pH value, electromagnetic field

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An Effective Brain Imaging Biomarker for AD and aMCI: ALFF in Slow-5 Frequency Band

Current Alzheimer Research ◽

10.2174/1567205018666210324130502 ◽

2021 ◽

Vol 18 ◽

Author(s):

Luoyu Wang ◽

Qi Feng ◽

Mei Wang ◽

Tingting Zhu ◽

Enyan Yu ◽

...

Keyword(s):

Brain Imaging ◽

Frequency Band ◽

Low Frequency ◽

Posterior Cingulate Cortex ◽

Angular Gyrus ◽

Imaging Biomarker ◽

Support Vector ◽

Frequency Bands ◽

Local Functional ◽

Left Angular Gyrus

Background: As a potential brain imaging biomarker, amplitude of low frequency fluc-tuation (ALFF) has been used as a feature to distinguish patients with Alzheimer’s disease (AD) and amnestic mild cognitive impairment (aMCI) from normal controls (NC). However, it remains unclear whether the frequency-dependent pattern of ALFF alterations can effectively distinguish the different phases of the disease. Methods: In the present study, 52 AD and 50 aMCI patients were enrolled together with 43 NC in total. The ALFF values were calculated in the following three frequency bands: classical (0.01-0.08 Hz), slow-4 (0.027-0.073 Hz) and slow-5 (0.01-0.027 Hz) for the three different groups. Subsequently, the local functional abnormalities were employed as features to examine the effect of classification among AD, aMCI and NC using a support vector machine (SVM). Results: We found that the among-group differences of ALFF in the different frequency bands were mainly located in the left hippocampus (HP), right HP, bilateral posterior cingulate cortex (PCC) and bilateral precuneus (PCu), left angular gyrus (AG) and left medial prefrontal cortex (mPFC). When the local functional abnormalities were employed as features, we identified that the ALFF in the slow-5 frequency band showed the highest accuracy to distinguish among the three groups. Conclusion: These findings may deepen our understanding of the pathogenesis of AD and suggest that slow-5 frequency band may be helpful to explore the pathogenesis and distinguish the phases of this disease.

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A Numerical Study on the Seismic Site Response of Rocky Valleys with Irregular Topographic Conditions

Journal of Multiscale Modelling ◽

10.1142/s1756973718500117 ◽

2019 ◽

Vol 10 (04) ◽

pp. 1850011 ◽

Cited By ~ 1

Author(s):

Mohammad Katebi ◽

Behrouz Gatmiri ◽

Pooneh Maghoul

Keyword(s):

Seismic Analysis ◽

Numerical Study ◽

Site Response ◽

Slope Angle ◽

Response Spectra ◽

Topographic Effects ◽

Combined Effects ◽

Acceleration Response ◽

Vertically Propagating ◽

Maximum Amplification

This paper investigates topographic effects of rocky valleys with irregular topographic conditions subjected to vertically propagating SV waves of Ricker type using a boundary element code. Valleys with two intersecting slopes, [Formula: see text] and [Formula: see text], are modelled in order to study their combined effects on ground motion. Presented in the form of pseudo-acceleration response spectra, results of this work can be extended to similar topographies. The main findings are: (i) [Formula: see text] (the first slope angle) and [Formula: see text] (L is the half width of the valley and [Formula: see text] is its corresponding height) have amplifying effects, and [Formula: see text] (the second slope angle) has de-amplifying effects on the site response. (ii) [Formula: see text] has a straight effect on intensifying the effects of both [Formula: see text] and [Formula: see text]. (iii) The combined effects of slope angles have been found to be important in modifying the response so more than a single slope should be considered for seismic analysis. (iv) Engineers should use the maximum amplification of 2.4 in case of valleys with the first and second slope angles below [Formula: see text].

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Disparity in interaural time difference improves the accuracy of neural representations of individual concurrent narrowband sounds in rat inferior colliculus and auditory cortex

Journal of Neurophysiology ◽

10.1152/jn.00284.2019 ◽

2020 ◽

Vol 123 (2) ◽

pp. 695-706

Author(s):

Lu Luo ◽

Na Xu ◽

Qian Wang ◽

Liang Li

Keyword(s):

Auditory Cortex ◽

Inferior Colliculus ◽

Interaural Time Difference ◽

Critical Role ◽

Low Frequency ◽

Time Difference ◽

Neural Representation ◽

Frequency Bands ◽

Neural Segregation ◽

Peripheral Auditory System

The central mechanisms underlying binaural unmasking for spectrally overlapping concurrent sounds, which are unresolved in the peripheral auditory system, remain largely unknown. In this study, frequency-following responses (FFRs) to two binaurally presented independent narrowband noises (NBNs) with overlapping spectra were recorded simultaneously in the inferior colliculus (IC) and auditory cortex (AC) in anesthetized rats. The results showed that for both IC FFRs and AC FFRs, introducing an interaural time difference (ITD) disparity between the two concurrent NBNs enhanced the representation fidelity, reflected by the increased coherence between the responses evoked by double-NBN stimulation and the responses evoked by single NBNs. The ITD disparity effect varied across frequency bands, being more marked for higher frequency bands in the IC and lower frequency bands in the AC. Moreover, the coherence between IC responses and AC responses was also enhanced by the ITD disparity, and the enhancement was most prominent for low-frequency bands and the IC and the AC on the same side. These results suggest a critical role of the ITD cue in the neural segregation of spectrotemporally overlapping sounds. NEW & NOTEWORTHY When two spectrally overlapped narrowband noises are presented at the same time with the same sound-pressure level, they mask each other. Introducing a disparity in interaural time difference between these two narrowband noises improves the accuracy of the neural representation of individual sounds in both the inferior colliculus and the auditory cortex. The lower frequency signal transformation from the inferior colliculus to the auditory cortex on the same side is also enhanced, showing the effect of binaural unmasking.

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