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In order to develop green energy, reduce carbon emissions, and alleviate global warming and the green energy crisis, many researchers focus on wave energy, using a device to convert wave energy into electricity. The three main types of wave energy converters are the overtopping type, the oscillating water column type, and the oscillating body type, and for most of them, the power generation efficiency is low. The research team in this paper proposed a wave energy converter for a wave-induced oscillation heave plate. The plate vibrates up and down under the action of waves, and the captured energy of the vibrating plate transfers the energy to the generator, so as to generate electricity. There is electricity only when there is vibration; therefore, the vibration characteristic of the converter is crucial to power generation. So, the vibration characteristics of the energy capture structure of the converter were studied experimentally. The test results show that the energy harvesting device can vibrate, and the vibration effect is good, which further indicates that the device can generate electricity. The effects of different wave conditions and system stiffnesses on amplitude and corresponding amplitude were studied, and the amplitude increases with the increase in wave height and period and decreases with the increase in system stiffness. The amplitude response decreases with the increase in wave height and system stiffness. Under the test conditions, the maximum amplitude of the system is 6.23 cm (when the wave period is 1.40 s, the wave height is 0.25 m, and the system stiffness is 1735.62 N/m), and the maximum amplitude ratio is 0.34 (when the wave period is 1.1 s, the wave height is 0.10 m, and the system stiffness is 1735.62 N/m). [ABSTRACT FROM AUTHOR]

The use of advanced brittle composites in engineering systems has necessitated robotic rotary ultrasonic machining to attain high precision with minimal machining defects such as delamination, burrs, and cracks. Longitudinal–torsional coupled (LTC) vibrations are created by introducing helical slots to a horn's profile to enhance the quality of ultrasonic machining. In this investigative research, modified ultrasonic horns were designed for a giant magnetostrictive transducer by generating helical slots in catenoidal and cubic polynomial profiles to attain a high amplitude ratio ( T A / L A ) and low stress concentrations. Novel ultrasonic horns with a giant magnetostrictive transducer were modelled to compute impedances and harmonic excitation responses. A structural dynamic analysis was conducted to investigate the effect of the location, width, depth and angle of helical slots on the Eigenfrequencies, torsional vibration amplitude, longitudinal vibration amplitude, stresses and amplitude ratio in novel LTC ultrasonic horns for different materials using the finite element method (FEM) based on the block Lanczos and full-solution methods. The newly designed horns achieved a higher amplitude ratio and lower stresses in comparison to the Bezier and industrial stepped LTC horns with the same length, end diameters and operating conditions. The novel cubic polynomial LTC ultrasonic horn was found superior to its catenoidal counterpart as a result of an 8.45 % higher amplitude ratio. However, the catenoidal LTC ultrasonic horn exhibited 1.87% lower stress levels. The position of the helical slots was found to have the most significant influence on the vibration characteristics of LTC ultrasonic horns followed by the width, depth and angle. This high amplitude ratio will contribute to the improved vibration characteristics that will help realize good surface morphology when machining advanced materials. [ABSTRACT FROM AUTHOR]

Wheel polygons pose a threat to the safety of train operations due to wheel fatigue, necessitating online identification. The online identification of wheel polygons predominantly relies on the axle box vertical nx (n-multiple integer of axle rotation frequency) signals generated by wheel polygons. The low-order vertical nx signals are easy coupling to other faults like axle cracks, leading to errors in wheel polygon identification. A signal decoupling method is crucial for removing the crack components from the vertical nx signal to obtain more accurate identification results for low-order wheel polygons. Employing principles of signal superposition for different faults, this article proposes a method to decouple the wheel polygon nx signal from the vertical nx signal by subtracting the crack-related portion. This method has been validated through an ABAQUS + SIMPACK online rigid-flexible coupling model, indicating that it significantly improves the accuracy of wheel polygon identification. The 1x amplitude of the decoupled signal decreased by 60.78%, and the 2x amplitude decreased by 55.79%. [ABSTRACT FROM AUTHOR]

The problem of reflection and transmission of inhomogeneous plane waves caused by incident quasi-longitudinal (qP) and quasi-shear vertical (qSV) waves at the interface between a fiber-reinforced thermoelastic solid under magnetic field and a fiber-reinforced thermoelastic solid is examined mathematically using Lord-Shulman theory. The impact of magnetic intensity on the phase speeds has been discussed. The boundary conditions are taken at the plane interface of the two half-spaces and the amplitude and the energy ratios are derived. Two plane waves, qP wave and qSV wave are modeled to incident at the plane interface which result in three reflected waves in one of the half-spaces and three transmitted waves in the other half-space. The effect of magnetic field on the amplitude ratios, the bulk energy ratios and the interacting energy ratios are analyzed numerically and the results are illustrated graphically. [ABSTRACT FROM AUTHOR]

Purpose: Utilization of advanced hard and brittle materials in engineering applications has led to the need of non-conventional machining techniques such as rotary ultrasonic machining (RUM) to achieve high dimensional accuracy and low machining defects (delamination, burr and cracks formation, etc.). RUM performance greatly depends on vibration amplitude at tool end which is achieved through appropriate ultrasonic horn design. Longitudinal–torsional coupled (LTC) vibrations, generated by incorporating helical slots in horn design, improve ultrasonic machining quality of hard and brittle materials. In present investigative work, modified ultrasonic horns were designed and analyzed for RUM by producing helical slots in quadratic and cubic Bezier horn profiles to achieve high amplitude ratio ( T A / L A ) within safe stress limits. Methods: Modal and harmonic analyses were performed to investigate the influence of depth ( D s ), width ( W s ), angle ( θ s ) and location ( L sp ) of helical slots on the modal frequencies, vibration amplitudes, torsional to longitudinal amplitude ratio and stresses in ultrasonic LTC Bezier horns using FEM. Modified ultrasonic horns were tested for three different materials: steel, aluminum, and titanium after validation with available literature. Results: Presently designed horns were found to attain high amplitude ratio and low stresses as compared to the commercial step LTC horn for same end diameters and length. Different stresses (shear, von Mises, radial, tangential and axial) were also computed and plotted along horn axial length for optimum designs and were found well below the endurance limit. Conclusions: For the same end conditions and length, cubic Bezier LTC ultrasonic horn is preferable to its quadratic counterpart due to 19.91 % higher amplitude ratio. However, stresses are 24.78 % less in quadratic Bezier LTC ultrasonic horn. The amplitude ratio attained by both types of LTC Bezier horns was found to be significantly greater than that in the commercial LTC step horn, with additional advantage of low stresses. Achievement of high amplitude ratio will help in reduced cutting force and improved surface quality of advanced hard and brittle materials as compared to standard LTC horn design. [ABSTRACT FROM AUTHOR]

In order to develop green energy, reduce carbon emissions, and alleviate global warming and the green energy crisis, many researchers focus on wave energy, using a device to convert wave energy into electricity. The three main types of wave energy converters are the overtopping type, the oscillating water column type, and the oscillating body type, and for most of them, the power generation efficiency is low. The research team in this paper proposed a wave energy converter for a wave-induced oscillation heave plate. The plate vibrates up and down under the action of waves, and the captured energy of the vibrating plate transfers the energy to the generator, so as to generate electricity. There is electricity only when there is vibration; therefore, the vibration characteristic of the converter is crucial to power generation. So, the vibration characteristics of the energy capture structure of the converter were studied experimentally. The test results show that the energy harvesting device can vibrate, and the vibration effect is good, which further indicates that the device can generate electricity. The effects of different wave conditions and system stiffnesses on amplitude and corresponding amplitude were studied, and the amplitude increases with the increase in wave height and period and decreases with the increase in system stiffness. The amplitude response decreases with the increase in wave height and system stiffness. Under the test conditions, the maximum amplitude of the system is 6.23 cm (when the wave period is 1.40 s, the wave height is 0.25 m, and the system stiffness is 1735.62 N/m), and the maximum amplitude ratio is 0.34 (when the wave period is 1.1 s, the wave height is 0.10 m, and the system stiffness is 1735.62 N/m).

The use of advanced brittle composites in engineering systems has necessitated robotic rotary ultrasonic machining to attain high precision with minimal machining defects such as delamination, burrs, and cracks. Longitudinal–torsional coupled (LTC) vibrations are created by introducing helical slots to a horn’s profile to enhance the quality of ultrasonic machining. In this investigative research, modified ultrasonic horns were designed for a giant magnetostrictive transducer by generating helical slots in catenoidal and cubic polynomial profiles to attain a high amplitude ratio (TA/LA) and low stress concentrations. Novel ultrasonic horns with a giant magnetostrictive transducer were modelled to compute impedances and harmonic excitation responses. A structural dynamic analysis was conducted to investigate the effect of the location, width, depth and angle of helical slots on the Eigenfrequencies, torsional vibration amplitude, longitudinal vibration amplitude, stresses and amplitude ratio in novel LTC ultrasonic horns for different materials using the finite element method (FEM) based on the block Lanczos and full-solution methods. The newly designed horns achieved a higher amplitude ratio and lower stresses in comparison to the Bezier and industrial stepped LTC horns with the same length, end diameters and operating conditions. The novel cubic polynomial LTC ultrasonic horn was found superior to its catenoidal counterpart as a result of an 8.45% higher amplitude ratio. However, the catenoidal LTC ultrasonic horn exhibited 1.87% lower stress levels. The position of the helical slots was found to have the most significant influence on the vibration characteristics of LTC ultrasonic horns followed by the width, depth and angle. This high amplitude ratio will contribute to the improved vibration characteristics that will help realize good surface morphology when machining advanced materials.

The need to create monitoring systems to equip the technological machinery of automated production determines the relevance of searching for parameters of acoustic signals that carry information about the course of treatment processes. The study of acoustic signals in various types of material processing allowed the identification of general features of changes in their spectral composition associated with variations in the power density of energy impact on processed material. The results of experimental work on various technological equipment, including blade processing and processing with concentrated energy flows, are presented in this work. It is shown that changes in the quality of processing in the form of increased tool wear, the concentration of erosion products during WEDM (wire electrical discharge machining), focal plane displacement during laser processing, etc., lead to a natural change in the ratio of acoustic signal amplitudes in the low frequency and high frequency ranges. This property can be used in monitoring systems for automatic equipment. [ABSTRACT FROM AUTHOR]

This paper presents the modeling of inhomogeneous plane waves reflecting from the stress free surface of a monoclinic magneto-thermoelastic rotating material. The effects of magnetic field and rotation on the phase speeds corresponding to quasi longitudinal, quasi thermal and quasi transverse-waves are examined. The amplitude and energy ratios corresponding to the reflected waves are derived with the help of boundary conditions. The effects of the incident angle, magnetic field and rotation on the amplitude and energy ratios are examined and discussed numerically. The sum of energy ratios has been examined and observed that it obeys the conservation law of energy. [ABSTRACT FROM AUTHOR]

Objective: To compare the amplitude ratio and P-wave latency of cervical vestibular evoked myogenic potentials (c-VEMPs) for bone conduction (BC) and air conduction (AC) stimulation in children with otitis media with effusion (OME). Material and methods: This is an observational study of a cohort of 27 children and 46 ears with OME. The c-VEMP amplitude ratio and P-wave latency were compared between BC and AC in children with OME and healthy age-matched children. Results: The c-VEMP response rate in children with OME was 100% when using BC stimulation and 11% when using AC stimulation. The amplitude ratio for BC was significantly higher in the OME group than the age-matched healthy control group (p = 0.004). When focusing on ears with an AC c-VEMP response (n = 5), there was a significant difference in the amplitude ratio between the AC and BC stimulation modes, but there was no significant difference in the AC results between the OME group and the age-matched control group. Conclusions: BC stimulation allows for reliable vestibular otolith testing in children with middle ear effusion. Given the high prevalence of OME in children, clinicians should be aware that recording c-VEMPs with AC stimulation may lead to misinterpretation of otolith dysfunction in pediatric settings. [ABSTRACT FROM AUTHOR]

Both natural and artificial seismic events are recorded by seismic stations without any discrimination. In this scope, discriminating the artificial and natural seismic events is an important task in terms of seismic risk analysis. This paper presents an open-source MATLAB based graphical user interface, ANQDS (Artificial and Natural Quake Discrimination Software), for discrimination of the artificial and natural seismic events. ANQDS is a user-friendly program that utilizes a semi-automatic algorithm based on the four different methods to determine the source of a seismic event: (a) amplitude ratio; (b) complexity; (c) power spectral density; and (d) short-time Fourier transform. It can automatically analyze a seismic event using the amplitude ratio and complexity methods, however, for the analyzes based on the power spectral density and short-time Fourier transform methods, it needs user support. The code employs the approaches called the linear and quadratic discriminant functions for statistical operations. Besides, the developed code can analyze a seismic event for each recording station and eventually reach a general result from these analyses. In order to test the performance and reliability of the developed algorithm, four different seismic events from Turkey have been analyzed. As a result, it was seen that ANQDS can discriminate these seismic events with success rates ranging from 87.37% to 100%. [ABSTRACT FROM AUTHOR]

Based on the propagation theory of elastic waves in frozen poroelastic media and elastic media, a theoretical model of saturated frozen soil and elastic solid bedrock is established. The phenomena of transmission and reflection of plane-P1 waves at the plane interface between saturated frozen soil and elastic solid bedrock are analyzed. The saturated frozen soil is lying on an elastic solid bedrock and is modeled as a porous material with a three-phase medium that contains two solids (soil skeleton and ice particles) and a compressible viscous fluid. First, analytical solutions for wave transmission and reflection in saturated frozen soil and elastic solid bedrock models are obtained. Then, the theoretical formulation is derived for the characteristic equations in saturated frozen soil and the amplitude ratios and energy ratios of transmitted and reflected waves. The numerical results are obtained and used to discuss the relationship between the amplitude ratios and energy ratios for transmitted and reflected waves and the incident angle, incident frequency, saturation, cementation parameters and contact parameters. This study shows that only compressional waves are present when the incidence angle is 0. As cementation parameters, saturation, porosity and contact parameters increase, the critical angle appears earlier. The trend of the amplitude ratios is similar to that of its energy ratios, but the change in the energy ratios is larger than that of the amplitude ratios. Each wave has different degrees of pulses when reaching the critical angle, among which the transmitted P wave and the reflected P1, S1 and S2 waves are the most significant. At higher saturation, it is observed that the amplitude ratio and energy ratio of the reflected S2 wave decrease significantly. [ABSTRACT FROM AUTHOR]

We present experimental results of resonant free surface oscillations within three circular moonpools arranged in tandem at forward, central, and aft positions of a fixed rectangular vessel in head waves. The piston mode resonance frequency is primarily captured, which decreases with the increase in the vessel draft. The aim is to study the effect of body diffraction on the free surface amplitude and phase of the oscillating water columns at the three locations. The results indicate that, in general, the forward moonpool has the highest response amplitude, whereas the relative amplitudes of the central and aft moonpools depend on the wave frequency. It is observed that the nondimensional response amplitude increases nonlinearly with decreasing wave steepness close to the resonance frequency, while the effect diminishes at lower wave frequencies. The oscillation phase differences between the moonpools show effects of wave-body interaction, a phenomenon dependent on the vessel draft and wave frequency. Finally, the study includes a comparison of the responses at the three moonpool locations betweenmultiple and single configurations. [ABSTRACT FROM AUTHOR]

In Soma Region, located in the western part of Turkey, both tectonic and anthropogenic source type of events are identified in earthquake catalogues by various seismology centers. Especially because of the low-magnitude quarry blasts, mistakes can be made in seismic catalogs in terms of source type, which can be further complicated by similar magnitude earthquakes. With this regard, the vertical component seismograms of 445 seismic events with a magnitude of Ml ≤ 2.5 recorded at the station SOMA, operated by Boğaziçi University Kandilli Observatory and Earthquake Research Institute Regional Earthquake–Tsunami Monitoring Center (KOERI–RETMC), were analyzed. First, two statistical analyses (Linear and Quadratic Discriminant Functions–LDF/QDF) were applied for amplitude ratio and complexity methods for 345 waveforms that have the same source types in both KOERI–RETMC catalogs and the first manual determination. The accuracies of the statistical approaches are varied between 87.25% and 97.39% and the better statistical classifier is the QDF for complexity method. Then, using the values obtained from two methods together, tree-based machine learning (ML) classifiers called as Random Forest (RF), Gradient Boosting (GB) and Support Vector Machine (SVM) were applied to the same data set. All classifiers provided as 100% success rate for quarry blasts' recordings, while earthquakes are categorized by RF, GB and SVM with 97.1%, 95.8% and 92.8%, respectively. Each ML algorithms were applied to the other 100 data identified as quarry blast on KOERI–RETMC catalogs but determined to be suspicious source types on first manual determination. Regarding to the outperforming RF and GB algorithms, the quarry blast recordings have just been reached as 53 and 55, respectively. Considering the accuracies of the ML algorithms in the testing and training data set, the source types of the low magnitude seismic events that are registered in the catalogs should be re-evaluated and refined in Soma Region using the station SOMA. [ABSTRACT FROM AUTHOR]

Cantilever vibration in an optical lever AFM is theoretically analyzed considering the effect of surface force and ambient fluid. The surface force between the tip and the sample is modeled using a cantilever with a spring and damping added to the tip, and the effect of ambient fluid on the cantilever vibration is analyzed using the bead model. The amplitude ratios of the forced vibration were derived by solving the equation of motion. There are discrepancies between the amplitude ratio derived from bending vibration theory and that obtained through the optical lever method. The amplitude ratio from bending vibration theory reveals that the effect of surface force dominates primarily below the second resonant frequency. The tip-added spring affects the resonant frequency shift and amplitude ratio, while the tip-added damping mainly affects the amplitude ratio at the resonant frequency. In contrast, the amplitude ratio considering the optical lever method reveals that anti-resonance occurs when the tip-added spring constant is positive, which is not observed in bending vibration theory. The amplitude ratio of the cantilever is modified by introducing a correction factor. The correction factor decreases with excitation frequency except for the frequency where the anti-resonance occurs. The correction factor becomes small when the ambient fluid has high density and viscosity.

ObjectiveIn order to achieve the accurate prediction of the amplitude response of a vortex-induced vibrating cylinder under the sub-critical Reynolds number, a method for establishing a Cl-A/D (lift coefficient-amplitude ratio)model of the forced vibration of the cylinder by numerical simulation is proposed.MethodsBased on the Realizable k-ε model, a two-dimensional numerical simulation of the forced vibration of a cylinder is carried out using the finite volume method. The calculated lift coefficient curves under different amplitude ratios A/D in the range of excitation frequency ratio fe/fn=1 are obtained. The lift coefficient corresponding to the maximum vibration velocity of the cylinder is then selected to establish the Cl-A/D model. ResultsThe results show that the overall trend of the Cl-A/D fitting curve is in good agreement with the predicted results of SHEAR7. At the same time, it is found that the "zero lift coefficient" points under each excitation frequency ratio fe/fn are all located near the amplitude ratio A/D=0.8, and the wake shedding mode changes around A/D=0.8 from "P+S" to "2P" (P represents a pair of vortex shedding with opposite rotation directions, and S represents a single vortex shedding). In the vortex-induced vibration experiment of a single cylinder, the maximum amplitude when "lock-in" occurs is around 0.8D. ConclusionsThe amplitude ratio corresponding to the "zero lift coefficient" of the Cl-A/D model of forced vibrating cylinder under sub-critical Reynolds number is consistent with the maximum response amplitude ratio of the cylinder under vortex-induced vibration, and the shedding mode of the wake vortex changes under this amplitude ratio.

Wave reflection phenomenon at the stress-free/rigid surface of a piezoelectric fiber-reinforced composite (PFRC) half-space is studied. The PFRC is micro-mechanically modeled using Strength of Materials (SM) and Rule of Mixtures (RM). Some of its electro-mechanical data are graphically shown and its advantages are discussed. An incident quasi-longitudinal (qP) wave generates reflected quasi-longitudinal (qP), quasi-transverse (qSV), and electroacoustic (EA) waves, whose propagation angles are graphically demonstrated. Closed-form expressions of energy ratios of reflected waves and interaction energy are obtained, which satisfy the Law of Conservation of Energy, thus validating this problem. Influences of incident angle, varying fiber volume fractions, and stress-free/rigid surfaces on amplitude/energy ratios are discussed. [ABSTRACT FROM AUTHOR]

This article deals with the behavior of reflection/transmission phenomena on the propagation of SH waves in a corrugated fluid-saturated porous layer sandwiched between heterogeneous viscoelastic and orthotropic half-spaces. Various mathematical tools such as Rayleigh's method of approximation, Snell's law, Crammer's law are applied to get the analytical expression for the reflection/transmission coefficient and energy ratio for each scattered wave. A numerical treatment has been performed for a particular model to study the nature of various affecting parameters such as heterogeneity, viscosity, porosity, angle of incidence, and wave number. A comparative study has been made for the graphical observation to show the effect of the various affecting parameters in the presence and absence of porosity. The reflection/transmission coefficient, energy ratio for each wave (regularly and irregularly reflected/transmitted wave) are calculated analytically and given a graphical representation for a particular model. It has been shown that the conservation of energy rule holds very well in the model. The finding of this article may be valuable in the field of seismology and geophysics to enhance the knowledge about the structure of rock in the interior of the Earth and its elastic property. [ABSTRACT FROM AUTHOR]

Reflection and refraction phenomenon pattern of elastic plane wave at the interface between anisotropic monoclinic elastic half-space and isotropic elastic half-spaces is studied. Closed-form expression for phase velocity is obtained. Reflection and transmission coefficients are obtained using the method of Cramer's rule in determinant form. Also, the energy ratios are calculated in terms of reflection and transmission coefficients. Numerical examples are considered to exhibit all the findings graphically. The energy conservation law is implemented at each angle of incidence to validate the numerical results, and it is found that energy ratios are in good agreement with the energy conservation law.

Three representative small and medium earthquakes in Shanxi seismic belt in recent years were taken as examples. By using different methods, such as the first motion of P-wave, first motion of P-wave combining P/SV/SH amplitude ratio, CAP (Cut and Past), and moment tensor inversion, the reliability and stability of focal mechanism solutions of small and medium earthquakes were analyzed and verified by gradually increasing calculation stations and selecting different data types and data quantities. The results indicate that in practice, 1) for a stable and reliable solution based on P-wave first motions, at least more than eight P-wave polarity data with clear initial motion and good inclusion in the earthquake are required; 2) for small earthquakes with inadequate station records, increasing the amplitude ratio data improves constraints on the results to a certain extent, but increasing the amplitude ratio data often significantly increases the contradiction ratio, while the constraints on the results are not continuously improved; 3) for ML≈3.2 earthquakes, the CAP method gives stable and reliable results, and for medium earthquakes with larger magnitude, moment tensor inversion method is also suggested to be an ideal choice to obtain reliable focal mechanism solutions.

The present paper proposes a non-contact ultrasonic testing method for the debonding inspection of metal-based composite structures, utilizing an improved electromagnetic acoustic transducer (EMAT). The enhanced EMAT incorporates a carbonyl iron powder coil backplate and a small butterfly coil to enhance the detecting ability for interfacial bonding. A two-dimensional finite element model is developed to quantify the effectiveness of the carbonyl iron powder coil backplate on increasing the eddy current density and the magnetic flux density in the specimen. An experimental setup was designed using the Ritec SNAP 5000 and the improved EMATs to examine an aluminium-epoxy resin composite structure. Ultrasonic C-scan images of the specimen's bonding interface were obtained from the experiment. Both simulation and experimental results show that carbonyl iron powder coil backplates can increase the efficiency of the EMATs. By investigating the influence of echo number on debonding detection, it was revealed that employing higher-order echoes and utilizing carbonyl iron powder as the coil backplate can enhance the debonding detection capability. The C-scan imaging results indicate that the utilization of high-order echoes enhances imaging quality, and the employment of high-quality miniaturized EMATs enhances the capability for quantitative analysis of debonding defects. [ABSTRACT FROM AUTHOR]

Face milling of AISI 2062 steel was applied an optimization technique by ANOVA based on optimal factorial method is proposed in this paper. Which cover dynamic behavior of facemill with different shim and cutting condition for reducing chatter by amplitude ratio method. To illustrate the effectiveness of this approach Experimental results are provided. Cutting tools Damping and stability of is very much essential now a day in VMC Milling Centre operations. During the experimental work we have done experiment with carbide shim followed by without shim and Stainless Steel shim to see drop in chatter. An experimental methodology was developed using the DOE (Design of experiment) technique. The optimal factorial method was used DOE for four factors having three levels. The main results are based on amplitude ratio and ANOVA analysis. Analysis of variance (ANOVA) was used to determine the effects of the cutting condition on vibration amplitude ratio in X, vibration amplitude ratio in Y. This is useful for evaluating This is useful for evaluating the stability of milling operations via time domain FFT and it validates with ANOVA by design expert 8.0.6. It is found that the most critical parameter in this study is Shim material. At high cutting speed and feed carbide shim and low and medium cutting speed and feed SS shim represent good result for reducing chatter. [ABSTRACT FROM AUTHOR]

Carbon fiber–reinforced plastic (CFRP) composites are prone to delamination, tearing, and burrs in conventional drilling. It has been proven that longitudinal–torsional coupled ultrasonic-assisted drilling (LTC-UAD) can significantly improve the hole quality of CFRP composites, where the amplitude ratio is a key parameter which directly affects the contact state between the cutting edge and the CFRP composite. This paper investigates the effect of amplitude ratios on the hole quality in LTC-UAD of CFRP composites by kinematic characteristic analysis and drilling experiments. The increased amplitude ratio increases the effective rake angle of the main cutting edge, sharping the cutting edge and reducing the thrust force by 29.6%. The increased amplitude ratio also causes the reduction of up to 20.1% and 49.22% in burr factor and hole wall surface roughness, respectively, but the reduction in the delamination factor is not significant. The variable direction shear effect contributes to the shearing fracture of the fibers, thereby reducing the burrs and delamination. The variable stress state makes the fibers more susceptible to shear fracture, but the scraping and polishing effect of the minor cutting edge helps to remove excess fiber fragments and coat the hole wall evenly with the resin to fill the cavities, which in turn reduces the hole wall surface roughness. Additionally, the secondary cutting action of minor cutting edge on the hole wall is enhanced by the increased amplitude ratio, which results in a larger diameter deviation but within the range of 0.012 mm. [ABSTRACT FROM AUTHOR]

As one of the most sophisticated structural types in rapid industrialized bridge construction technology, the fabricated beam bridge has been widely used in road network system for a long time. The prominent disease of this type of structure is the degradation of the lateral cooperative capability, that is, the deterioration of the hinge joint stiffness. This paper proposes a monitoring and evaluation method for the lateral connection stiffness based on the multiple-beams theory, which has the concise physical meanings and can be easily implemented. On this basis, a new damage identification method and index extracted from the mode shape information of the system is proposed in this paper. To verify the effectiveness of the proposed indicator ARCR, Shanghai Tongji Road viaduct is taken as the engineering background. Results shows that the theoretical analysis results are consistent with physical truth, the proposed indicator can reasonably reflect the degradation degree of the joint and locate the damaged joint. [ABSTRACT FROM AUTHOR]

The problems of elastic wave propagation in the micropolar porous materials have been attempted under the interaction of micro-rotation tensor and porous distribution in this material. We obtain the existence of three coupled longitudinal and two coupled shear waves propagating with different phase speeds. Numerically, the phase speed and attenuation of five basic waves are computed. We consider the incident plane waves at the boundary of micropolar porous materials, then the dispersive nature of the incident waves is studied and the existence of critical angle for the incident shear wave is found. The amplitude and energy ratios of various reflected waves for the incident coupled longitudinal and shear waves are obtained analytically and numerically. Further, the influence of different material parameters is studied using dispersion relation and the relevant numerical values. [ABSTRACT FROM AUTHOR]

Hexagonal, carbon-based structures were prepared on bare and treated copper foil substrates by Chemical Vapor Deposition at 1075 ᵒC using a graphite box for limiting copper reactivity with hydrocarbon gases during growth reactions. Spectroscopic ellipsometry with a digital camera was used to collect the amplitude ratio and the phase of structures various spots. The amplitude ratio of hexagonal structures on copper substrates was collected based on substrate treatment type and thickness as well as reaction zone conditions and methane flow rates. Matched amplitude ratio was obtained only for 75 µm thick acetic acid copper foil substrates inside and outside the graphite box at a low methane flow rate of 0.2 sccm. Moreover, the amplitude ratio of 75 µm bare copper foil and 75 µm electro-polished copper foil substrates at methane flow rates of 0.2 - 0.3 sccm were unmatched. Ellipsometric parameters data use potential is assessment of graphene layer thickness on different surfaces. Data shows dependence of the amplitude ratio on the surface roughness of copper foil, gas concentrations and reaction zone conditions.

Reflection and refraction phenomenon pattern of elastic plane wave at the interface between anisotropic monoclinic elastic half-space and isotropic elastic half-spaces is studied. Closed-form expression for phase velocity is obtained. Reflection and transmission coefficients are obtained using the method of Cramer's rule in determinant form. Also, the energy ratios are calculated in terms of reflection and transmission coefficients. Numerical examples are considered to exhibit all the findings graphically. The energy conservation law is implemented at each angle of incidence to validate the numerical results, and it is found that energy ratios are in good agreement with the energy conservation law. [ABSTRACT FROM AUTHOR]

This paper presents a novel design for a high resolution microelectromechanical systems (MEMS) technology based resonant gyroscope using the mode-localization effect in weekly coupled resonators (WCRs) as a mechanism for sensing the input angular rate. The design consists of a single proof mass with two three degree-of-freedom (3-DoF) WCRs systems attached on either side. The MEMS gyroscope is designed according to the microfabrication constraints of the foundry process, silicon-on-insulator multi-user MEMS process (SOIMUMPs). The shift in the resonance frequency values, amplitude ratios of the WCRs, and amplitude ratios difference of two sets due to electrostatic stiffness perturbation, corresponding to the input angular rotation, are discussed as an output metric for the measurement of angular rate. The results show that the amplitude ratio difference as an output metric allows achieving a linear output response and large dynamic range in comparison to the shift in the amplitude ratio and resonance frequency in 3-DoF WCRs in a single set. The dynamic range and resolution of the MEMS gyroscope in terms of maximum allowed resonators amplitude and the noise floor is discussed. The proposed MEMS gyroscope design has a sensitivity of 62830 ppm/°/ $s$ based on a difference in the amplitude ratios of resonators in two 3-DoF WCRs systems and a dynamic range of ±100 °/s. The resolution of the MEMS gyroscope is $31.09\times 10^{-6\circ }$ /s which is significantly higher than existing MEMS gyroscopes and is comparable to traditional bulky ring laser gyroscopes. This high resolution makes the proposed MEMS gyroscope design suitable for use in applications such as earth rotation rate measurement for gyrocompassing and high precision robotics.

Contemporaneous groundwork focuses on the reflection and deflection pattern of seismic wave at the alliance junction amid anisotropic monoclinic and isotropic elastic semi-infinite materials bar. Expressions for phase velocity in closed form have been obtained. The coefficients of the reflection and deflection seismic phase velocity are achieved in the determinant form by using the Cramer's rule. Moreover, the energy ratios of the current research are acquired and validated in context of reflected/deflected wave coefficients. Some quantitate instances are taken into account to exhibits the outcomes of the study. Law of energy conservation has been executed at every angle of incidence to vindicate the considered quantitative outcomes and it is observed that energy ratios are in well accordance with the law of energy conservation. A unique case study is done with extended case of considered structure, where there a best validated graphical presentation with theory is available. Findings of the study are highly applicable to the motion detectors, signal processing, wireless communications, and sensors incorporation to enhancing the work efficiency of surface wave acoustic devices and equipment's of the defense system. [ABSTRACT FROM AUTHOR]

In this paper, performance analysis of the cross-eye jamming effect under mechanical defects is dealt with. By using a numerical analysis-based approach, the performance analysis method proposed in this paper is closer to the not approximated empirical mean square difference (MSD) than the first-order Taylor approximation-based performance analysis method and the second-order Taylor approximation-based performance analysis method proposed in previous studies. In other words, the effects of amplitude ratio perturbation and phase difference perturbation on performance degradation are quantitatively analyzed. Note that the numerical integration is adopted to derive an analytic expression of the MSD. [ABSTRACT FROM AUTHOR]

Shallow crustal velocity and Poisson's ratio structures are of key importance to understand rock properties and near‐surface tectonic deformation and evolution. We propose a novel imaging method to acquire such information at individual stations by joint inversion of amplitude ratios between the horizontal and vertical components of both teleseismic P and S waves. Our synthetic experiments demonstrate the validity of the method in recovering subsurface structures up to ∼8–10 km depth. We apply this method to construct the velocity and Poisson's ratio images along a NW‐SE‐trending seismic array within the Sichuan Basin, southwestern China. The results reveal well developed stratification and localized high Poisson's ratio anomalies, which reflect a long‐term stable sedimentary environment and fault‐related deformation in response to the Cenozoic Tibet–basin collision, consistent with geological observations. Our new method builds a bridge between fine‐scale near‐surface seismic exploration and large‐scale deep passive‐source imaging, especially for areas of weak seismicity. Plain Language Summary: Both seismic wave travel time and amplitude bear important information on subsurface structures and can therefore be used to image them. Travel time is commonly used in conventional seismic imaging methods, whose imaging accuracy, however, is heavily dependent on the distribution of stations and/or events. Amplitude is rarely taken into account when imaging because of poorly understood information about complex source functions. Here, we propose to utilize amplitude ratios between the horizontal and vertical components of teleseismic body waves to image the subsurface velocity and Poisson's ratio structures at individual stations. Our new method does not require any source information or high‐density raypath coverage and provides an intermediate approach between fine‐scale (∼km) near‐surface seismic exploration and large‐scale (several tens to hundreds and thousands of kilometers) deep passive‐source imaging. Considering today's abundant broadband seismic data around the world, this method is promising for their further reutilization. Key Points: Joint inversion of P and S wave amplitude ratios enables the better recovery of the shallow crustal velocity and Poisson's ratiosLateral traceability of strongly stratified structures may reflect a long‐term stable sedimentary environment within the Sichuan BasinThe Cenozoic Tibet–Sichuan Basin collision may have led to fault‐related deformation localized in the sedimentary cover of the basin [ABSTRACT FROM AUTHOR]

Moiré signal subdivision is essential to the application of gratings. Focusing on the complexity and difficulty of quadrature compensation for the Moiré signals, we propose a new method that can directly subdivide nonorthogonal Moiré signals. A detailed description of the digital subdividing system for this method is provided herein. Compared with conventional methods, the proposed method requires fewer hardware resources and features shorter delays. The effects of various parameters on the subdivision process are discussed, and the quantitative relationships between the signal amplitude ratio, signal sampling frequency ratio, and subdivision value are determined. Finally, evaluation tests are performed using a laboratory-made field-programmable gate array subdivision circuit. The results confirmed the effectiveness of the subdivision method, revealing a subdivision error of less than $0.6^{\prime \prime }$. [ABSTRACT FROM AUTHOR]

Determination of anisotropy has crucial to assess the quality of the concrete structures. The signal amplitudes of ultrasonic wave measured on different surfaces of concrete can be used for determining the anisotropy. In this study, a total of 27 cube reinforced concrete samples with different strengths (low, medium and high) have prepared. First, signals of ultrasonic waves (P and S waves) have obtained to use direct measurement technique from two opposite surfaces of the all samples. After, Fast Fourier Transform (FFT) has applied on ultrasonic signals for determining amplitude anisotropies and amplitude ratios. Finally, amplitude anisotropies and ratios have correlated with concrete strength, porosity and reinforcement diameter depending on curing conditions and new equations have developed. In addition, these equations have determined both depending on curing conditions and regardless of curing type. As a result, it has been shown that P and S wave amplitude anisotropies and ratios of reinforced concrete increased with decreasing of concrete strength. These increasing have obtained higher for P wave than that of S wave. [ABSTRACT FROM AUTHOR]

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. • Using the increase in seismic amplitudes (RSAM) and seismic amplitude ratios caused by migrating seismic sources as the FFM observables. • Fitting the FFM to the body wave attenuation model to forecast eruption onsets • Forecasting (retrospectively) the onset of the 2010 Piton de la Fournaise eruption. [ABSTRACT FROM AUTHOR]

We propose a blind digital modulation format identification (MFI) method for coherent optical fiber communication systems. Based on the evaluation of differential phase distribution ratio (DPDR) and average of amplitude ratio (AAR), a monitoring factor R, the product of DPDR and AAR, is defined to distinguish whether the signal modulation format is QPSK, 16-QAM, or 64-QAM. Simulation and experimental results demonstrate that the proposed MFI can perform an identification when the OSNR of the incoming signal is greater than 12 dB. The proposed method needs no extensive training data sets and can tolerate residual chromatic dispersion (-210-210 ps/nm) and phase noise.

The single-phase-to-earth fault (SPTEF) current is weak in neutral ineffectively grounded systems. High fault impedance, noise and arc impair the fault feature, which increases the difficulty of faulty feeder detection. Based on the propagation characteristics of zero-mode transients (ZTs), this paper proposes a faulty feeder detection criterion by utilizing the amplitude information of the ZTs captured at both terminals. To conduct the criterion, the historical data of the ZTs recorded at both terminals of each feeder with a bus fault is collected. The standard amplitude ratios of the frequency components in the ZTs of each feeder are extracted by S-transform. After a SPTEF is detected in the system, the actual amplitude ratios of the ZTs are calculated and compared with the standard ones. Theoretical analysis and simulation indicate that the maximum ratio between the standard and actual ratios corresponds to the faulty feeder. In implementation of the criterion, both high sampling frequency and accurate synchronization are not required. A 10kV single-end radial distribution network is constructed by PSCAD/EMTDC. Various fault simulations are carried out and the calculation results demonstrate that the proposed criterion has high reliability and is not affected by neutral grounding mode, fault initial condition, high impedance fault (HIF) and noise.

• Clinical outcome in patients with acute ischemic stroke due to extracranial internal carotid artery occlusion is most accurately predicted by the somatosensory evoked potential side-to-side amplitude ratio. • An upper extremity motor deficit is incompatible with elicitability of the somatosensory evoked potentials in the acute phase. • Median somatosensory evoked potentials may contribute to improving the indication for urgent internal carotid artery recanalization. Changes in the N20/P25 amplitude of somatosensory evoked potentials (SEP) of the median nerve have been found to correlate with those in cortical regional cerebral blood flow (rCBF). Our study presents the use of median nerve SEP amplitude in predicting the clinical outcome of urgent surgical internal carotid artery (ICA) recanalization. A total of 27 patients suffering an acute ischemic stroke (AIS) with extracranial ICA occlusion within 24 h were prospectively recruited. The primary preoperative endpoints included the SEP amplitude absolute value (SEP-amp) and the SEP amplitude side-to-side ratio (SEP-ratio). Clinical outcome at 3 months postoperatively was assessed using the modified Rankin scale (mRS-3M). The positive predictive values (PPVs) for SEP-amp and SEP-ratio were 95.5% and 100%, respectively, with the negative predictive values (NPVs) being 60.0% and 100%, respectively. The SEP-ratio correlated fully with mRS-3M. The median SEP side-to-side N20/P25 amplitude ratio seems to be a very strong positive and negative predictor of the clinical outcome of urgent recanalization of an extracranial ICA occlusion. The results suggest that cortical evoked activity may help in selection patient for surgical recanalization and predict clinical recovery after an acute ischemic stroke. [ABSTRACT FROM AUTHOR]