Attenuation Equation Research Articles

Strain-Based Heating of Polymers under Ultrasonic Excitation

Ultrasonic welding is the most common type of polymer joining used in industry today. It is critical that the energy transfer and heating mechanisms be well understood to enable the use of this process for more challenging applications. This work seeks to provide new tools to predict the heating rate in a molded polymer part excited by ultrasonic energy. Current assumptions for the mechanics of energy transfer are explored, and new equations for attenuation and strain-based heating are proposed.

Seismicity of Morocco and simulation of 08.09.2023 earthuake consequnces with “Extremum” system application

This paper reports the use of regional intensity attenuation equations for the territory of Morocco by modeling the impact of the destructive earthquake of September 8, 2023 in the country. The relevance of the study follows from the needed reliable estimates of possible loss due to earthquakes in order to aid the decision-making process for the response and the proper choice of a search and rescue strategy for the heavily affected settlements. The paper has for its goal the calibration of the “Extremum” system seismic intensity attenuation models for the territory of Morocco. Our study is the first to analyze the seismic intensity attenuation equations obtained by researchers at different times with a view to their applicability to near real time loss assessment for strong events occurring in the area of study. We investigate as well how the results of earthquake loss simulation are affected by regional damage matrixes. Computer simulation was applied to the assessment of the possible impact due to the September 8, 2023 earthquake using the “Extremum” system developed with authors’ participation.This paper provides preliminary results of modeling the impact of the Morocco earthquake, as well as an assessment of the convergence achieved by calculated and observed intensities for various intensity prediction equations obtained before for the Morocco and adjacent areas within the Alpine-Himalayan seismically active belt.

The coupled band gap of longitudinal wave in metamaterial-based double-rod containing resonators

This study investigates the coupled band gap and vibration propagation characteristics of elastic waves in a metamaterial elastic double-rod system with attached periodic resonators. We derive the band gap structure and vibration attenuation equations of double-rod structure using the spectral element method, Bloch’s theorem, and the transfer matrix method. The validity of the coupled band gap is confirmed through forced vibration response analysis. Furthermore, we examine the effects of various parameters on the double-rod system, revealing that coupled band gaps exist with the average vibration attenuation rates of −50.23 dB for rod one and −47.87 dB for rod two, respectively. Remarkably, by adjusting the double-rod parameters, both the band gap frequency range and vibration attenuation ability of the coupled band gap can be adjusted to meet specific engineering requirements in low-frequency regions. This research contributes to developing continuous mechanical structures featuring coupled band gaps.

SITE-SPECIFIC DISAGGREGATION ANALYSIS OF RECENT EARTHQUAKE ON THE AMBON COAST

Seismic activity in the eastern region of Indonesia, particularly in Ambon, has been a matter of great concern because of its high tectonic activity. The devastating magnitude 6.5 earthquake in September 2019, which resulted in fatalities and significant damage, highlighted the region’s vulnerability and emphasized the importance of understanding the area’s seismic hazards. Although previous studies have been conducted, this study aims to fill critical gaps in the literature by using the latest seismic data until 2022 and updated attenuation equations. Disaggregation analysis is employed to identify ground motion characteristics, that are crucial for calculating synthetic ground motion acceleration. Under risk-targeted maximum considered earthquake (MCER) conditions, the study results show a peak ground acceleration of 0.444 g, with spectral acceleration at 0.2 s reaching 1.093 g, which decreases to 0.350 g at 1.0 s. Notably, background earthquake sources play a dominant role in contributing to the region’s high seismic hazard potential. The results of this study highlight the urgency of updating Indonesia’s national seismic hazard map. The study also recommends future studies to explore additional parameters of newly discovered faults to enhance understanding of fault movements and their impacts in the study area.

Simulation of January 22, 2024 Mw=7.0 Uqturpan earthquake consequences with the "Extremum" system application

This paper reports the use of intensity attenuation equations for the territory of the Northern Tien Shan by modeling the impact of a powerful destructive earthquake of January 22, 2024 in China. The relevance of the study follows from the needed reliable estimates of possible losses due to earthquakes in order to aid the decision making process for the response and the proper choice of a search and rescue strategy for the heavily affected settlements. The paper has as its goal the calibration of the Extremum system models for the territory of the Northern Tien Shan. Our study is the first to analyze the seismic intensity attenuation equations obtained by researchers at different times with a view to their applicability to near real time loss assessment for strong events occurring in the area of study. We investigate how the results of seismic attenuation modeling are affected by the ellipse compression factor k. and the source parameters of a strong event as determined by different seismological agencies in the alert mode. Computer simulation was applied to assess the possible impact of the January 22, 2024 earthquake using the "Extremum" system developed with our participation. This paper provides results of modeling the impact of the 2024 Uqturpan earthquake, as well as an assessment of the convergence achieved by calculated and observed intensities for various intensity prediction equations obtained before for China, Kyrgyzstan and adjacent areas within the Gissar-Kokshaalsky seismically active belt.

Characterization of energy dissipation of particle system in high velocity compaction

Energy transmission and dissipation during HVC lead to the uneven pressing force of the powder in the die cavity, which ultimately affects the densification and mechanical properties of powder metallurgy products. This study used the discrete element method (DEM) to monitor the energy transmission and dissipation of the powder system during HVC, investigate the relationship between the dissipation of kinetic energy and the impact energy during the loading stage, and consider the relationship between the strain energy release rate and the impact energy during the unloading stage. The results show that the boundary energy (impact energy) is mainly converted into strain, frictional, and damping energy, of which the kinetic energy is only an intermediate form and its attenuation equation is also obtained. The larger the porosity of the particle system is, the larger the dissipation factor β is, and the more serious the energy dissipation is. It can be found that the release rate of the strain energy gradually decreases with increasing impact energy, and the strain energy is significantly higher than the frictional energy in the green compacts.

Truncated pseudo-differential operator √−▽2 and its applications in viscoacoustic reverse-time migration

SUMMARY The pseudo-differential operator with symbol |k|α has been widely used in seismic modelling and imaging when involving attenuation, anisotropy and one-way wave equation, which is usually calculated using the pseudo-spectral method. For large-scale problems, applying high-dimensional Fourier transforms to solve the wave equation that includes pseudo-differential operators is much more expensive than finite-difference approaches, and it is not suitable for parallel computing with domain decomposition. To mitigate this difficulty, we present a truncated space-domain convolution method to efficiently compute the pseudo-differential operator $\sqrt{-\nabla ^2}$, and then apply it to viscoacoustic reverse-time migration. Although $\sqrt{-\nabla ^2}$ is theoretically non-local in the space domain, we take the limited frequency band of seismic data into account, and constrain the approximated convolution stencil to a finite length. The convolution coefficients are computed by solving a least-squares inverse problem in the wavenumber domain. In addition, we exploit the symmetry of the resulting convolution stencil and develop a fast spatial convolution algorithm. The applications of the proposed method in Q-compensated reverse-time migration demonstrate that it is a good alternative to the pseudo-spectral method for computing the pseudo-differential operator $\sqrt{-\nabla ^2}$, with almost the same accuracy but much higher efficiency.

Forecasting the onset of volcanic eruptions using the increase in seismicity during magma ascent

The Failure Forecast Method (FFM) has been used to forecast the onset of volcanic eruptions with varying degrees of success. The method involves fitting its empirical equation to precursory observables, e.g., seismic data. Current models explaining the empirical equation assume that the seismic observables used (e.g., seismic event-rate, seismic moment-rate or seismic energy-rate) are related to accelerated fracture growth. In these models, such fracture growth results in an apparent increase in seismic activity. In this study, however, we propose an alternative explanation for the increase in seismicity culminating in volcanic eruptions. We suggest that the increase in seismicity, particularly in the seismic amplitudes, can result from ascending seismic sources towards the surface and that the increase can be used for eruption forecasts using the FFM. Our argument is based on the need for magma to migrate towards the surface to produce an eruption.To test our argument, we used synthetic and field/real data and fitted them with the FFM model. The synthetic data is generated using the body wave attenuation equation, and the real data is from the Piton de la Fournaise eruption on January 2nd, 2010. We used seismic amplitudes and seismic amplitude ratios as the precursory observables and used a combination of Simulated Annealing and Bayesian Inversion algorithms to obtain the best-fit parameters of the FFM model and their posterior distributions. For the synthetic cases, we found that the method gave reasonable estimates of failure or eruption time, suggesting that the seismic amplitudes and the seismic amplitude ratios can be used for forecasting using the FFM. For the field/real cases, the results gave information about the timing of magma chamber failure, magma propagation, and the eruption onset. Our results highlight an example of modelling volcano monitoring data with the FFM that gives reasonable estimates of eruption time even if the data may not fully represent failure processes. We suggest that the result may still be reasonable owing to the empirical and asymptotic nature of the FFM combined with the underlying physics of magma and seismic migrations.

Vibration Characteristics and Location of Buried Gas Pipeline under the Action of Pulse Excitation

In this paper, the attenuation of sound waves in underground gas pipelines and the vibration characteristics of pipelines are studied, and the feasibility and effectiveness of acoustic measurement of PE pipelines are verified. In this paper, the attenuation equation of sound waves in an underground gas transmission pipeline is derived based on the propagation characteristics of gas and the vibration characteristics of the pipeline itself. In order to verify the experimental results, we conducted an experimental test on the air pipeline model and verified the feasibility and effectiveness of the acoustic measurement of the PE pipeline through the test under the action of pulse excitation. Then, we detect the background noise, design the test scheme according to the characteristics of the buried pipeline, and select the test site for field test. In the test process, we collected the test data and obtained the spectrum diagram of the test data by fast Fourier transform (FFT). By analyzing the results of the spectrogram, we find that the pulse signal can penetrate the medium composed of the pipe formation, but the amplitude of the sound will be sharply attenuated. At the same time, according to the size of the peak in the spectrum, we can determine the location of the pipe. In summary, the feasibility and effectiveness of acoustic measurement of the PE pipeline are verified through experimental tests, and attenuation equations based on acoustic wave propagation characteristics and pipeline vibration characteristics are proposed. It has important practical application value for the safety monitoring and positioning of the buried gas pipeline.

Seismic Load Design of Rukoh Dam Suppletion Tunnel in Pidie Regency, Aceh, Indonesia, Based on Deterministic and Probabilistic Seismic Hazard Analyses

The Rukoh Dam suppletion tunnel construction site in Pidie Regency, Aceh province, is located 5.6 kilometers from the Seulimeum-South segment of the active Sumatran fault. The active fault features a strike-slip fault mechanism with a slip rate of 7.0 millimeters per year and a maximum earthquake-recorded magnitude of 6.9 Mw. Considering that the construction site is located less than 10 kilometers from the active fault, which may cause earthquakes with a magnitude of at least 6 Mw, the SNI 1729:2019, which describes the procedures for planning earthquake resistance for buildings and non-building structures, requires the seismic load to be designed based on the site-specific responses analysis. Determination of the seismic load using a deterministic seismic hazard analysis was the objective of this study. The seismic load based on the probabilistic seismic hazard analysis by Pusat Studi Gempa Nasional (PusGen) in 2017 is also compared. The 2017 Indonesian Earthquake Source and Hazard Map were used to find out about the fault mechanism, slip rate, deterministic magnitude, orientation, and coordinates of traces. The deterministic seismic hazard analysis was conducted using EZ-FRISK 8.07 software and attenuation equations with shallow crustal earthquake sources for fault and shallow background earthquake sources, i.e., the Boore-Atkinson NGA 2014, the Campbell-Bozorgnia NGA 2014, and the Chiou-Youngs NGA 2014 equations. The deterministic analysis based on those attenuation equations predicted the active fault to result in a peak ground acceleration (PGA) value of 0.66 g at the construction site of the Rukoh Dam suppletion tunnel. In comparison, the probabilistic hazard analysis conducted by Pusat Studi Gempa Nasional (PusGen) in 2017 indicated a peak ground acceleration (PGA) of 0.537 g. Therefore, the seismic load is recommended for the structural designs of the embankment dam and the other infrastructures, particularly the suppletion tunnel.

Analysis of liquefaction potential in the Malalayang beach area, North Sulawesi

North Sulawesi Province was locating in a tectonically active area, affected by subduction of the Sulawesi Sea plate, Sangihe, and Halmahera. These plates are still active to provide an earthquake threat. Several large earthquakes that came from various plates around Manado City have been recorded. A large earthquake that shakes sandy soil can produce liquefaction events. The Malalayang beach area, located in the West of Manado City a part of Malalayang Beach Area Arrangement Work Package and the Bunaken Village Ecotourism Arrangement, was chosen as the research object to analyse the possibility of liquefaction. The research begin with collect boring testing data, lab test data, and earthquake data such as the moment of magnitude and Peak Ground Acceleration (PGA). This study also uses various methods or attenuation equations to determine the peak ground acceleration from the history of earthquakes obtained from multiple sources. Based on the data obtained from the field and laboratory tests, data processing is carried out to determine the liquefaction potential. From the results of the Liquefaction Potential Index (LPI) calculation, it was found that the Malalayang Beach Area has the potential for the occurrence of the liquefaction phenomenon.

Two layer shallow water equations for wave attenuation of a submerged porous breakwater

In this study, we investigate the effectiveness of submerged porous medium on reducing incoming wave amplitude using a Two-Layer Shallow Water Type model. A new formula for the wave transmission coefficient, which is a ratio of the wave transmitted amplitude to the incoming wave amplitude, is then derived from the model analytically. This coefficient is the main instrument for evaluating the effectiveness of the porous submerged breakwater. In addition, the finite volume method on a staggered grid is used to solve the model numerically. We then validate the numerical scheme by comparing simulation results to the analytical solutions and experimental data. The verified scheme is ready to be implemented to simulate and predict wave transmission coefficient over actual coastal areas. Further, we examine the effect of the dimension and characteristics of the porous medium on the wave attenuation. We believe that these findings would be beneficial in the design of a coastal protection system.

A predictive algorithm to identify ever smoking in medical claims-based epidemiologic studies

To develop and validate an algorithm to estimate probability of ever smoking using administrative claims. Using population-based samples of Medicare-aged individuals (121,278 Behavioral Risk Factor Surveillance System survey respondents and 207,885 Medicare beneficiaries), we developed a logistic regression model to predict probability of ever smoking from demographic and claims data. We applied the model in 1,657,266 additional Medicare beneficiaries and calculated area under the receiver operating characteristic curve (AUC) using presence or absence of a tobacco-specific diagnosis or procedure code as our "gold standard." We used these "gold standard" and lung/laryngeal cancer codes to over-ride predicted probability as 100%. We calculated Spearman's rho between probability from this full algorithm and smoking assessed in prior Parkinson disease studies, by substituting our observed and prior ("true") smoking-Parkinson disease odds ratios into the attenuation equation. The predictive model contained 23 variables, including basic demographics, high alcohol consumption, asthma, cardiovascular disease and associated risk factors, selected cancers, and indicators of routine medical usage. The AUC was 67.6% (95% confidence interval 67.5%-67.7%) comparing smoking probability to tobacco-specific diagnosis or procedure codes. Spearman's rho for the full algorithm was 0.82. Ever smoking might be approximated in administrative data for use as a continuous, probabilistic variable in epidemiologic analyses.

A case study of blasting vibration attenuation based on wave component characteristics

A typical blasting vibration wave is a composite wave, and its attenuation law is affected by the type of dominant wave component. The purpose of the present study is to establish an attenuation equation of the peak particle velocity (PPV), taking into account the attenuation characteristics of P-, S- and R-waves in the blasting vibration wave. Field blasting tests were carried out as a case to specifically apply the proposed equation. In view of the fact that the discrete properties of rock mass will inevitably cause the uncertainty of blasting vibration, we also carried out a probability analysis of PPV uncertainty, and introduced the concept of reliability to evaluate blasting vibration. The results showed that the established attenuation equation had a higher prediction accuracy, and can be considered as a promising equation implemented on more complex sites. The adopted uncertainty analysis method can comprehensively take account of the attenuation law of blasting vibration measured on site and discrete properties of rock masses. The obtained distribution of the PPV uncertainty factor can quantitatively evaluate the reliability of blasting vibration, which is a powerful and necessary supplement to the PPV attenuation equation. • The dominant wave component type affected the attenuation law of blasting vibration. • A PPV attenuation equation considering the wave components was established. • A field blasting test verified the feasibility of the proposed equation. • An uncertainty probability analysis method of blasting vibration was proposed. • Both lithological parameters and vibration law were considered in the method.

A study on the annual industrial permeability attenuation phenomena of MBR membrane

Defined “industrial permeability VMD” as the permeable volume (m3) of unit membrane area (1000 m2) at unit time (1 day) and unit cross-membrane pressure difference (1 kPa). The VMD is directly calculated by using the daily computer’s records of Xi’an Siyuan A2/O-MBR system. After excluding five anomalies, 71% to 78% of effective industrial permeability was obtained from water yield and cross-membrane pressure difference of 3520 days original data. Each 25 effective industrial permeability was artificially divided into a group unit, and calculated the VMD arithmetic average of the group units. Then, group units are reduced into the annual units. A power equation is fitted into annual VMD arithmetic mean and annual units as the annual industrial permeability attenuation equation. The predicting value of industrial permeability is calculated by the previous attenuation equation, and the measuring value of industrial permeability is calculated by the present attenuation equation. The error ratio is defined as the relative size of the predicted and measured values. Calculating the annual industrial permeability attenuation is straightforward, simple, and convenient. It also show that the prediction period should not be less than three years, so it is best to choose four to five years.

New assessment of the probabilistic seismic hazard analysis for the greater Jakarta area, Indonesia

The greater Jakarta area is located in west Java and has a high earthquake risk due to the subduction of the Australian Plate beneath the Eurasian Plate. Previous hazard studies have been carried out using various seismic probability approaches. This study presents a new probabilistic seismic hazard analysis (PSHA) by developing an updated seismic model for the crustal active fault database, using a new set of ground motion prediction equations (GMPE), and taking into consideration the effect of site amplification. The logic tree method was used to quantify the epistemic uncertainty of the source parameter components and the attenuation equation was used. We calculate the peak ground acceleration (PGA) and spectral acceleration (SA) for West Java, including metropolitan Jakarta, Bogor and Serang, which have the greatest concentrations of population and business. We found that the mean PGA reaches 1.0 g or a 2% probability of exceedance in 50 years, including site amplification factors. The seismic hazard is dominated by the shallow crustal fault near metropolitan Jakarta. The result of this study may be useful for updating the existing Indonesian hazard map.

A Comprehensive Correction Method for Radiation Distortion of Multi-Strip Airborne Hyperspectral Images

Airborne hyperspectral imaging plays an increasingly important role in environmental monitoring. However, due to the limitations of the acquisition conditions, there are uneven radiation and chromatic aberrations in the mosaic data. Accurate preprocessing of the original data is the premise of qualitative and quantitative remote sensing. In this study, we proposed a comprehensive radiation distortion correction method that integrates radiation attenuation difference correction, topographic correction, and multi-strip images consistency adjustment (RA-TOC-CA). First, the radiation attenuation equation was constructed by combining the viewing geometry, terrain, and the elevation difference between the UAV and the ground to eliminate the radiation attenuation difference of pixels acquired at the different instantaneous field of view (IFOV). Second, an improved kernel-driven BRDF model was built combining terrain information and illumination-viewing (flight attitude and sensor IFOV) geometry to eliminate the radiation unevenness and BRDF distortion caused by topography. Third, adjusting the reflectance of multi-strip images according to the homonymous points’ reflectance of adjacent strips should be equal, eliminating the radiation differences between multiple strips. Based on multi-strip airborne hyperspectral images collected in the Shaanxi province of China, the correction results of the RA-TOC-CA method were compared with those of the SCS+C and Minnaert+SCS methods regarding various evaluation criteria. The results showed that SCS+C and Minnaert+SCS can reduce the topographic effect but cannot eliminate the reflectance difference at the edges of adjacent images, and SCS+C overcorrects the reflectance. RA-TOC-CA weakened the topographic effects and brightness gradient, which was physically stable and generalizable. Compared with previous studies, RA-TOC-CA provided a complete radiation distortion correction method for airborne hyperspectral images and had a solid theoretical basis. This study introduces an effective method for radiation distortion correction of airborne hyperspectral images and provides technical support for large-scale applications of hyperspectral images.

Multi-Band Acoustic Monitoring of Aerial Signatures

The acoustic monitoring, omni-directional system (AMOS) in the Galileo Project is a passive, multi-band, field microphone suite designed to aid in the detection and characterization of aerial phenomena. Acoustic monitoring augments the Project’s electromagnetic sensors suite by providing a relatively independent physical signal modality with which to validate the identification of known phenomena and to more fully characterize detected objects. The AMOS system spans infrasonic frequencies down to 0.05[Formula: see text]Hz, all of audible, and ultrasonic frequencies up to 190[Formula: see text]kHz. It uses three distinct systems with overlapping bandwidths: infrasonic (0.05[Formula: see text]Hz – 20[Formula: see text]Hz), audible (10[Formula: see text]Hz – 20[Formula: see text]kHz), and ultrasonic (16[Formula: see text]kHz – 190[Formula: see text]kHz). The sensors and their capture devices allow AMOS to monitor and characterize the tremendous range of sounds produced by natural and human-made aerial phenomena, and to encompass possible acoustic characteristics of novel sources. Sound signals from aerial objects can be captured and classified with a single microphone under the following conditions: the sound reaches the sensor; the sound level is above ambient noise; and the signal has not been excessively distorted by the transmission path. A preliminary examination of the signal and noise environment required for the detection and characterization of aerial objects, based on theoretical and empirical equations for sound attenuation in air, finds that moderately loud audible sources (100[Formula: see text]dB) at 1[Formula: see text]km are detectable, especially for frequencies below 1[Formula: see text]kHz and in quiet, rural environments. Infrasonic sources are detectable at much longer distances and ultrasonic at much shorter distances. Preliminary aircraft recordings collected using the single, omni-directional audible microphone are presented, along with basic spectral analysis. Such data will be used in conjunction with flight transponder data to develop algorithms and corresponding software for quickly identifying known aircraft and characterizing the sound transmission path. Future work will include multi-sensor audible and infrasonic arrays for sound localization; analysis of larger and more diverse data sets; and exploration of machine learning and artificial intelligence integration for the detection and identification of many more types of known phenomena in all three frequency bands.

Wave-based numerical investigation on diffraction correction for a low-height barrier in energy-based sound propagation model for road traffic noise

In energy-based noise propagation prediction methods, such as CNOSSOS-EU in Europe and ASJ RTN-Model in Japan, sound propagation is calculated by using the equation of sound attenuation by the geometrical divergence of the sound power from a sound source and adding various attenuation corrections such as diffraction effect and ground effect. In the ASJ RTN-Model, the insertion loss due to a semi-infinite barrier to a free field is generally used for the diffraction correction for a single barrier, the top of which is regarded as a knife wedge, whereas the diffraction correction for a low-height barrier is different from that for a general single barrier. It is given as the insertion loss due to a low-height barrier to a semi-infinite barrier, the top height of which is at the ground surface level, in a free field: the diffraction correction is zero when the low-height barrier is 0 m high. However, its range of application is not clear. In this paper, the diffraction correction for a low-height barrier is discussed by comparing the results of three-dimensional wave-based numerical analysis and propagation calculations using the ASJ RTN-Model.

Calculation of hole spacing and surrounding rock damage analysis under the action of in situ stress and joints

In situ stress and joints have a significant impact on the propagation and attenuation pattern of blast stress waves, and they are two important factors that must be considered for tunnel blasting hole network deployment. This paper proposes a blast stress wave attenuation equation and a peripheral hole distance calculation method under the combined action of in situ stress and joints. First, the static and dynamic parameters of the jointed slate are obtained by drilling core samples in the field and conducting indoor tests. Next, considering the geometric and physical attenuation of the blast stress wave, the attenuation formula of the blast stress wave under the combined action of in situ stress and joints is derived. Based on the theory of the combined action of stress waves and explosive gas, a formula for calculating the peripheral hole distance that integrates the effects of in situ stress, joints, and tensile strength of the rock body is proposed. Finally, LS-PREPOST software is used to analyze the damage to the surrounding rock, verified by an on-site blasting test. The results show that the blast stress wave attenuation formula proposed in this paper can accurately predict the stress wave peak value under the combined action of in situ stress and joints. Combining the geological conditions and blasting parameters of the Bayueshan Tunnel study section, the optimal peripheral hole spacing is calculated to be 45 cm. The average over-excavation value of the grade IV surrounding rock is controlled within 22 cm and the over-consumption of concrete per linear meter is controlled within 100% using the peripheral hole layout method and the hole network layout parameters proposed in this paper. The research results provide a reference for the control of over-excavation and under-excavation in large-section tunnel blasting.