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Matched field processing (MFP) is an established technique for source localization in known multipath acoustic environments. Unfortunately, in many situations, imperfect knowledge of the actual propagation environment and sidelobes due to modal interference prevent accurate propagation modeling and source localization via MFP. To suppress the sidelobes and improve the method's robustness, a linear frequency-difference matched field processing (LFDMFP) method for estimating the source range is proposed. A two-neighbor-frequency high-order cross-spectrum between the measurement and the replica of each hydrophone of the vertical line array is first computed. The cost function can then be derived from the dual summation or double integral of the high-order cross-spectrum with respect to the depth of the hydrophones and the candidate sources of the replicas, where the range that corresponds to the minimum is the optimal estimation. Because of the larger modal interference distances, LFDMFP can efficiently provide only one optimal range within the same range search interval rather than some conventional matched field processing. The efficiency of the presented method was verified using simulations and experiments. The LFDMFP unambiguously estimated the source range in two experimental datasets with average relative errors of 2.2 and 1.9%. [ABSTRACT FROM AUTHOR]

The dynamical characteristics of the zonal wavenumber 1 (s = 1) Rossby-gravity (RG) wave are examined using recently available reanalysis data for the whole neutral atmosphere over 16 years. An isolated peak is detected in the two-dimensional zonal wavenumber-frequency spectra that likely corresponds to the theoretically-expected s = 1 RG mode at heights of z = 30, 50, 65, and 80 km. The wave period of the spectral peak is approximately 1.3 days, which is close to one day. The s = 1 RG wave is successfully extracted using a band-pass filter after removing the diurnal tide with quite large amplitudes. The s = 1 RG wave exhibits a characteristic seasonal variation: the geopotential height (GPH) amplitudes are largest in the winter hemisphere in the stratosphere and lower mesosphere while enhancement is observed in both the winter and summer hemispheres in the upper mesosphere. Phase structures are examined in detail for a strong case. The horizontal phase structure at each height is consistent with the normal mode theory. The vertical phase structure is approximately barotropic from the lower stratosphere to the upper mesosphere at 30°N and 30°S where the amplitudes are large. [ABSTRACT FROM AUTHOR]

This study investigates the thermo-mechanical behavior of generalized thermoelastic mediums under the influence of gravitational fields, incorporating two-temperature effects through the Lord–Shulman and dual-phase-lag models. Focusing on a plane surface subjected to an arbitrary normal force and maintained at isothermal conditions, analytical expressions for conductive temperature, thermodynamic temperature, displacement components, and force stresses are derived using normal mode analysis. Numerical results, presented graphically, consider the application of thermal force. Comparative analyses between the dual-phase-lag and Lord-Shulman models are conducted, examining the impact of gravity and the two-temperature effect. Engineering applications of these findings can enhance the understanding of thermal management in materials subjected to varying gravitational environments, such as aerospace structures and thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Data-derived normal mode extraction is an effective method for extracting normal mode depth functions in the absence of marine environmental data. However, when the corresponding singular vectors become nonunique when two or more singular values obtained from the cross-spectral density matrix diagonalization are nearly equal, this results in unsatisfactory extraction outcomes for the normal mode depth functions. To address this issue, we introduced in this paper a range-difference singular value decomposition method for the extraction of normal mode depth functions. We performed the mode extraction by conducting singular value decomposition on the individual frequency components of the signal's cross-spectral density matrix. This was achieved by using pressure and its range-difference matrices constructed from vertical line array data. The proposed method was validated using simulated data. In addition, modes were successfully extracted from ambient noise. [ABSTRACT FROM AUTHOR]

This manuscript addresses a significant research gap in the study by employing a mathematical model of photo thermoelastic wave propagation in a rotator semiconductor medium under the effect of a magnetic field and initial stress, as well as ramp-type heating. The considered model is formulated during the photothermal theory and in two-dimensional (2D) electronic-elastic deformation. The governing equations represent the interaction between the primary physical parameters throughout the process of photothermal transfer. Computational simulations are performed to determine the temperature, carrier density, displacement components, normal stress, and shear stress using the application of Lame's potential and normal mode analysis. Numerical calculations are carried out and graphically displayed for an isotropic semiconductor like silicon (Si) material. Furthermore, comparisons are made with the previous results obtained by the others, as well as in the presence and absence of magnetic field, rotation, and initial stress. The obtained results illustrate that the rotation, initial stress, magnetic field, and ramp-type heating parameter all have significant effects. This investigation provides valuable insights into the synergistic dynamics among a magnetization constituent, semiconducture structures, and wave propagation, enabling advancements in nuclear reactors' construction, operation, electrical circuits, and solar cells. [ABSTRACT FROM AUTHOR]

We consider circular Rayleigh problem which is incompressible, inviscid axial flows to axisymmetric disturbances. For this problem, we derived unbounded parabolic instability region which intersects with Batchelor and Gill semicircle instability region under certain condition. This has been illustrated with examples. Furthermore, we obtained supremum bound for the growth rate of an unstable mode, amplification factor. [ABSTRACT FROM AUTHOR]

The poro-thermoelastic problem with two-temperature, under the influence of the gravitational field and the rotation was investigated. The solution to the problem is presented in the context of lord and Shulman's theory of thermoelasticity with one relaxation time. We applied normal mode analysis to solve the resulting non-dimensional coupled partial differential equations. Effect of rotation, gravitational field, two-temperature parameter and porosity parameter on non-dimensional displacements, thermodynamic temperature, conductive temperature, excess pore water pressure and stresses has been discussed. Numerical analyses are given graphically in the square (2D) to illustrate the effect of these parameters. Some particular cases of interest are deduced from the present investigation. [ABSTRACT FROM AUTHOR]

A unique three-dimensional model of generalized thermoelasticity, incorporating a single relaxation time and relying on stress gradient nonlocal elasticity, is presented in this study. The fundamental coupled equations governing the model are applied to a semi-infinite spatial medium with a rigidly fixed bounding surface, which is exposed to a time-dependent thermal shock. The general solution for the field variables is obtained in a closed form through the utilization of normal mode analysis and the eigenvalue approach technique. Numerical results, specific to a substance resembling copper, are provided for the field variables. Parametric studies are conducted to assess the impact of elastic nonlocality on various physical quantities. The graphical representation reveals a noteworthy influence of the nonlocal parameter on the field variables. The study further discusses and compares predictions from the new model with the Lord and Shulman theory of generalized thermoelasticity. Ultimately, the article concludes with a summary of key remarks. [ABSTRACT FROM AUTHOR]

Normal mode separation and information extraction are popular topics in marine acoustics. The extraction of modal wavenumbers and modal depth functions using the data of a vertical line array is beneficial to various applications. In this paper, we systematically introduce a normal mode separation method based on the consistency restraint of the horizontal wavenumber, obtain the modal depth functions using the singular value decomposition (SVD) method, determine the vertical distribution of the horizontal wavenumber, and determine the SVD accuracy by the consistency of modal wavenumbers on the vertical direction. Moreover, this method can be used to determine the SVD accuracy without true depth functions. When the degeneracy problem leads to a poor SVD effect, the linear relation between the degenerate and true modes is obtained, and the minimum standard deviation of the vertical distribution of the modal wavenumbers is taken as the loss function, thus optimizing the SVD result and improving the accuracy of modal wavenumber estimation. The proposed method is validated using simulated data. In addition, the modes are successfully extracted from ambient noise.

Matched field processing (MFP) is an established technique for source localization in known multipath acoustic environments. Unfortunately, in many situations, imperfect knowledge of the actual propagation environment and sidelobes due to modal interference prevent accurate propagation modeling and source localization via MFP. To suppress the sidelobes and improve the method’s robustness, a linear frequency-difference matched field processing (LFDMFP) method for estimating the source range is proposed. A two-neighbor-frequency high-order cross-spectrum between the measurement and the replica of each hydrophone of the vertical line array is first computed. The cost function can then be derived from the dual summation or double integral of the high-order cross-spectrum with respect to the depth of the hydrophones and the candidate sources of the replicas, where the range that corresponds to the minimum is the optimal estimation. Because of the larger modal interference distances, LFDMFP can efficiently provide only one optimal range within the same range search interval rather than some conventional matched field processing. The efficiency of the presented method was verified using simulations and experiments. The LFDMFP unambiguously estimated the source range in two experimental datasets with average relative errors of 2.2 and 1.9%.

The use of autonomous vehicles (AVs) in transportation at signalized intersections is proposed to improve safety, efficiency, and sustainability. The discussion shall thus focus more on the impacts of different AV driving behaviors to some key transportation metrics solely at signalized intersections. Among the parameters considered are travel time, queue length, delay, and speed. This is clear from one such holistic study that Cautious AV behavior would reduce accidents, but on the other way around, it might increase traffic delays and lead to congestion at signalized junctions. Aggressive AVs will improve the flow of traffic but face problems in safety in this kind of set-up. Normal AV operation A balanced approach that offers intermediary levels of travel time and safety. The review further investigates the environmental effects of various driving patterns within signalized intersections, where it notes that there are noticeable differences in emissions and fuel consumed if the driving behavior is taken into consideration. It goes further into the implications for traffic management and control systems, noting challenges and opportunities while integrating AVs into existing infrastructure and spotlighting at signalized intersections. Paramount to the review are the considerations of safety, regulatory frameworks, and mitigating strategies relevant to AV behavior at signalized intersections. In so doing, this review seeks to inform future research and policy decisions with a nuanced understanding of how various AV driving behaviors affect signalized intersection performance, seeking to optimize AV benefits while mitigating possible risks at critical traffic junctures. [ABSTRACT FROM AUTHOR]

The purpose of the current study is to establish the deformation in a two-dimensional, isotropic, rotating half-space with gravitational field and initial stress that also has a heat source at the half boundary-space under magnetic field for Green and Naghdi II model. For the solution of the required problem, the methodologies of normal mode and approximate eigenvalues has been utilized. For graphical representation of different physical quantities such as displacement components, stress components, as well as the temperature distribution, Matlab software has been used. These results were compared with previous results in the same direction, and it was found that the treatment method for the aforementioned problem may form a basis for examining the effect of each of the gravitational field, magnetic field, rotation, and initial pressure on a thermally elastic body in the form of half an area without energy decay when neglecting some external influences. [ABSTRACT FROM AUTHOR]

The manuscript provides a thorough solution for the propagation of waves in a generalized homogeneous and isotropic thermo-photo-electric semiconductor medium. The main focus lies in the analysis of the two-dimensional (2D) issue in the presence of a magnetic field while adding optoelectronic excitation mechanisms. The governing equations exhibit coupling and encompass multiple factors, including relaxation time and porosity (voids) parameters. The governing equations are solved utilizing the normal mode technique, resulting in equations for the quasi-static electric field, heat conduction, carrier density (plasma waves), elastic waves, and the constitutive relationships of the thermo-magneto-photo-electric medium. This investigation considers the boundary conditions of plasma, thermal, and mechanical stress to determine the main physical variables involved. The objective of this research is to examine the effects of several thermo-magneto-photo-electric models, characteristics related to porous structures (voids), as well as time and spatial coordinates on a range of physical quantities. The impacts are examined through the visual analysis of graphical representations. [ABSTRACT FROM AUTHOR]

The Earth's magnetosphere supports a variety of Magnetohydrodynamic (MHD) normal modes with Ultra Low Frequencies (ULF) including standing Alfvén waves and cavity/waveguide modes. Their amplitudes and frequencies depend in part on the properties of the magnetosphere (size of cavity, wave speed distribution). In this work, we use ∼13 years of Time History of Events and Macroscale Interactions during Substorms satellite magnetic field observations, combined with linearized MHD numerical simulations, to examine the properties of MHD normal modes in the region L > 5 and for frequencies <80 mHz. We identify persistent normal mode structure in observed dawn sector power spectra with frequency‐dependent wave power peaks like those obtained from simulation ensemble averages, where the simulations assume different radial Alfvén speed profiles and magnetopause locations. We further show with both observations and simulations how frequency‐dependent wave power peaks at L > 5 depend on both the magnetopause location and the location of peaks in the radial Alfvén speed profile. Finally, we discuss how these results might be used to better model radiation belt electron dynamics related to ULF waves. Plain Language Summary: The solar wind constantly disturbs plasma in the near‐Earth space environment on a broad range of frequencies. However, plasma waves in the Earth's magnetosphere, a region of space where the Earth's magnetic field plays a dominant role in shaping plasma dynamics, often exhibit standing wave structure with a narrow range of frequencies. In other words, the magnetosphere selects standing waves with discrete frequencies from drivers with a broadband frequency spectrum. These standing waves have properties that depend on the size of the magnetosphere and plasma wave speeds. In this study, we use a database of magnetic field measurements from the Time History of Events and Macroscale Interactions during Substorms satellites along with numerical simulations to isolate natural frequencies from noisy and variable driving conditions and extract standing wave spatial structure. We show how the standing wave properties change as the outer boundary of the magnetosphere and internal wave speeds change. We finally discuss how the properties of these standing waves might be used to improve space weather models. Key Points: Magnetohydrodynamic normal modes are identified using ∼13 years of observations and comparisons with numerical simulationsRadial Alfvén speed profile peaks outside 8 Earth radii significantly alter frequencies and spatial structure of normal modesFrequencies and nodal structure of cavity/waveguide modes vary with magnetopause location, with power peaks well inside the magnetopause [ABSTRACT FROM AUTHOR]

This work demonstrates deformation in hygrothermoelastic medium with an overlying non-viscous fluid of uniform thickness. A constant mechanical force is applied along the fluid-layer. The normal-mode analysis technique is applied to solve the governing equations of the medium. The analytical expressions of displacement, moisture concentration, temperature distribution, and stresses are obtained for the hygrothermoelastic medium and depicted graphically for different values of fluid-layer depth. The finding of this work is that the values of the aforementioned physical quantities decrease with an increase in the fluid-layer, which justifies the decaying nature of waves with depth. The novelty of the problem is that no research has been carried out so far for analyzing hygrothermoelastic medium subjected to thermoelastic deformation.

Malfunction of the CFTR protein results in cystic fibrosis, one of the most common hereditary diseases. CFTR functions as an anion channel, the gating of which is controlled by long-range allosteric communications. Allostery also has direct bearings on CF treatment: the most effective CFTR drugs modulate its activity allosterically. Herein, we integrated Gaussian network model, transfer entropy, and anisotropic normal mode-Langevin dynamics and investigated the allosteric communications network of CFTR. The results are in remarkable agreement with experimental observations and mutational analysis and provide extensive novel insight. We identified residues that serve as pivotal allosteric sources and transducers, many of which correspond to disease-causing mutations. We find that in the ATP-free form, dynamic fluctuations of the residues that comprise the ATP-binding sites facilitate the initial binding of the nucleotide. Subsequent binding of ATP then brings to the fore and focuses on dynamic fluctuations that were present in a latent and diffuse form in the absence of ATP. We demonstrate that drugs that potentiate CFTR’s conductance do so not by directly acting on the gating residues, but rather by mimicking the allosteric signal sent by the ATP-binding sites. We have also uncovered a previously undiscovered allosteric ‘hotspot’ located proximal to the docking site of the phosphorylated regulatory (R) domain, thereby establishing a molecular foundation for its phosphorylation-dependent excitatory role. This study unveils the molecular underpinnings of allosteric connectivity within CFTR and highlights a novel allosteric ‘hotspot’ that could serve as a promising target for the development of novel therapeutic interventions.

Despite being widely recognized, the importance of deep layers thermohaline and mixing processes in the ocean circulation and variability is still poorly investigated, especially in the Mediterranean Sea. This limits understanding and parametrizing deep dynamics, which result in evident biases in the global circulation representation by observations and numerical ocean simulations. Having access to hydrological datasets, collected on a whole water column, we investigated the abyssal stratification and its variability of the Ionian Sea (Central Mediterranean). Applying multiple analyses, we found a tidal‐period oscillation and the resulting activation of mixing, pointing out that the combined effect of stratification, morphology, and tides has a key role in enhancing local diapycnal diffusivity in the deepest layers, being a mechanism that connects the whole water column with a compelling impact on the vertical transport of heat and tracers. Plain Language Summary: The presence of a quasi‐homogeneous density layer in the deep sea made it possible to observe a periodic effect: the layer acts like a "cushion" that is pulled up and then readjusted in circa 12 hr, which is the period typical of tides. The fact that tides can propagate down to the sea interior impacting the deep processes, down to 3,000 m of depth, is not so straightforward to observe. The deep ocean has a very slow dynamic, and the physical‐chemical phenomena involved are still mostly unknown. Key Points: Near‐full‐depth Conductivity‐Temperature‐Depth (CTD) casts data collected in the Ionian Sea with an unorthodox methodology allowed resolving tidal scaleThe temperature and salinity diagram depicted typical water masses for the Ionian area including a dense abyssal water massThe analyses showed a periodic pulsation and an activation of mixing in the abyssal layer due to the baroclinic internal tide [ABSTRACT FROM AUTHOR]

This paper discovers a new finding regarding Christiaan Huygens' coupled pendulums. The reason Christiaan Huygens' coupled pendulums obtain synchrony is that the coupled pendulums are subject to a harmonic forcing. As the coupled pendulums swing back and forth, they generate a harmonic force, which, in turn drives the coupled pendulums, such that the two pendulums swing in synchrony once the angular frequency of the generated harmonic forcing satisfies a certain condition. The factor that determines the angular frequency of the generated harmonic forcing is the effective length of the pendulum, as its angular frequency solely depends on the length of the pendulum that swings about a fixed point. In other words, it is the effective length of the coupled pendulum that determines whether the coupled pendulum achieves synchrony or not. The novelty of this article is that the author explains and analyzes the synchronization behaviour of Christiaan Huygens' coupled pendulums from the frequency and harmonic-forcing perspectives. [ABSTRACT FROM AUTHOR]

Abstract Despite being widely recognized, the importance of deep layers thermohaline and mixing processes in the ocean circulation and variability is still poorly investigated, especially in the Mediterranean Sea. This limits understanding and parametrizing deep dynamics, which result in evident biases in the global circulation representation by observations and numerical ocean simulations. Having access to hydrological datasets, collected on a whole water column, we investigated the abyssal stratification and its variability of the Ionian Sea (Central Mediterranean). Applying multiple analyses, we found a tidal‐period oscillation and the resulting activation of mixing, pointing out that the combined effect of stratification, morphology, and tides has a key role in enhancing local diapycnal diffusivity in the deepest layers, being a mechanism that connects the whole water column with a compelling impact on the vertical transport of heat and tracers.

This paper aims to modify the generalized thermoelasticity theory of Lord–Shulman. Higher-order time-derivative terms are incorporated to get accurate field variables. The refined theory is employed to examine the inclusion of a magnetic field, a two-temperature parameter, and the viscoelastic effects on a thermoelastic medium with two temperatures. The problem has been solved analytically and numerical data have been obtained by utilizing the normal mode technique. The analytic expressions of the displacements, stresses, dilatation, thermodynamic and conductive temperatures are outlined and investigated. The outcomes are reported for future comparison, and some are presented graphically in 2D and 3D plots. Comparisons with the existing literature due to the classical coupled and simple Lord–Shulman thermoviscoelasticity theories are made. The effects of many parameters are discussed.

The two-dimensional deformation of a generalized thermoelastic half-space with voids and microtemperatures under the action of a mechanical force was investigated. The effect of the voids and microtemperatures in this half-space on the displacements, the stresses, the temperature distribution, the change in the volume fraction field, and the first heat flux momentum in it was determined on the basis of the normal-mode analysis with the use of the Lord–Shulman and Green–Lindsay theories for an insulated boundary. [ABSTRACT FROM AUTHOR]

The direction-of-arrival (DOA) estimation of an underwater bottom-mounted horizontal linear array (HLA) based on weighted phase velocity has been proposed in this paper. The directional response is mainly affected by differences in the modal phase velocities and the sound speed of the water column. Based on the mode theory, the acoustic intensity distribution characteristics and beam deviation were analyzed. The beamforming result obtained provides a distinguishing feature of bearing deviation when the measured sound speed was used. By applying the modal weighted phase velocity instead, source bearing can be well estimated. Particularly, in the presence of a thermocline, the propagating modes can be selected on the basis of the mode trapping theory. Both surface and submerged sources were taken into account based on the experimental data, and the deviation was well explained and reduced. For a source near the end-fire direction, the bearing estimation error was reduced from several degrees to tenths of degrees. [ABSTRACT FROM AUTHOR]

The current research article deals with the study of deformation in a non-homogeneous orthotropic micropolar medium. It is assumed that the functionally graded material has non-homogeneous mechanical properties in the x-direction. The exact analytical expressions for the displacement and stress components are obtained in the physical domain by using the normal mode analysis technique. These components are then computed numerically using MATLAB software for aluminum epoxy composite as micropolar material and are also depicted graphically to show the variations of physical quantities. The comparisons have been carried out to show the effect of anisotropy on all physical quantities. [ABSTRACT FROM AUTHOR]

In this article the photothermal and void parameters of a semiconductor rotational medium are investigated when there is a fixed thermal relaxation time. We obtain the displacement, temperature, stress components, and carrier density concentration in a thermoelastic solid. Considering the normal mode technique under the effectiveness of the rotation, photothermal, and voids on the obtained components were graphically drawn. A comparison was made between the results obtained, taking into account the presence or ignorance of rotation, photothermal, and voids. The outcomes point out a strong impact of the voids, rotation, photothermal, and the thermal relaxation on the phenomenon and agree with the physical results. The results agree with the previous results obtained by the others when the rotation and voids vanish. [ABSTRACT FROM AUTHOR]

This paper discovers a new finding regarding Christiaan Huygens’ coupled pendulums. The reason Christiaan Huygens’ coupled pendulums obtain synchrony is that the coupled pendulums are subject to a harmonic forcing. As the coupled pendulums swing back and forth, they generate a harmonic force, which, in turn drives the coupled pendulums, such that the two pendulums swing in synchrony once the angular frequency of the generated harmonic forcing satisfies a certain condition. The factor that determines the angular frequency of the generated harmonic forcing is the effective length of the pendulum, as its angular frequency solely depends on the length of the pendulum that swings about a fixed point. In other words, it is the effective length of the coupled pendulum that determines whether the coupled pendulum achieves synchrony or not. The novelty of this article is that the author explains and analyzes the synchronization behaviour of Christiaan Huygens’ coupled pendulums from the frequency and harmonic-forcing perspectives.

The direction-of-arrival (DOA) estimation of an underwater bottom-mounted horizontal linear array (HLA) based on weighted phase velocity has been proposed in this paper. The directional response is mainly affected by differences in the modal phase velocities and the sound speed of the water column. Based on the mode theory, the acoustic intensity distribution characteristics and beam deviation were analyzed. The beamforming result obtained provides a distinguishing feature of bearing deviation when the measured sound speed was used. By applying the modal weighted phase velocity instead, source bearing can be well estimated. Particularly, in the presence of a thermocline, the propagating modes can be selected on the basis of the mode trapping theory. Both surface and submerged sources were taken into account based on the experimental data, and the deviation was well explained and reduced. For a source near the end-fire direction, the bearing estimation error was reduced from several degrees to tenths of degrees.

Algorithms working in mode space instead of directly matching the received complex sound pressure were developed to improve computational efficiency and robustness, but these algorithms may be inconvenient to apply in practice because manual operations are often inevitable when performing modal filtering. Based on a phase-matched filter, an imperfect matching scheme named the modal phase based matched impulse response (MP-MIR) is proposed to estimate the source range rapidly and conveniently with a single hydrophone. The field to be matched is still the received complex sound pressure. The replica field is a sum of several "phase" modes, which can be efficiently and conveniently synthesized merely with the horizontal wavenumbers of normal modes and the source–receiver range. The effectiveness of the proposed MP-MIR was demonstrated in localizing 84 emissions along a weakly range-dependent track at ranges of 2.54–20 km in the South China Sea. Although it was found, from cross-correlation coefficients, that the received signals showed strong variation even between adjacent emissions, MP-MIR outperformed the classical matched impulse response (MIR) with a lower standard deviation in most cases, demonstrating good robustness and potential for practical applications. [ABSTRACT FROM AUTHOR]

Numerical simulation is applied to consider the propagation of a low-frequency sound pulse in a shallow-water waveguide, which consists of three fluid layers: a water layer (30 m thick, with a sound speed of 1500 m/s), a gas-saturated sediment layer (0.4 m thick, 300 m/s), and a lower half-space (1560 m/s). A similar situation takes place in Lake Kinneret. It is shown that when the source and receiver are located near the bottom at a distance of about 10 waveguide depths from each other, two types of pulses are well observed in the received signal, significantly separated by the arrival time. First, a group of pulses arrives, corresponding to the sound speed in the water layer, then a single pulse, the postcursor, arrives with a significant delay and corresponds to sound propagation in the low-velocity gas-saturated sediment layer. Mode analysis shows that the postcursor is a very unusual first mode (a so-called inleak normal mode) trapped in the gas-saturated layer like an oceanic underwater sound channel. The propagation velocity of the pulse of the first mode is close to the sound speed in the gas-saturated layer in a quite wide frequency range, which makes it possible to estimate this speed from the arrival time of the postcursor. [ABSTRACT FROM AUTHOR]

We propose a novel microLED pixel circuit for mobile and wearable displays. For Normal and AOD mode operation, we applied PWM & PAM hybrid driving and PAM driving, respectively. Under the 4‐duty emission condition, we confirmed that the Vth compensation of the PWM unit, and the grayscale expression for each mode. [ABSTRACT FROM AUTHOR]

During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of honeybees (Apis mellifera) matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six bees were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a scanning Doppler laser vibrometer. The lowest normal mode of the wings was the first longitudinal bending mode and, at 602±145 Hz, was greater than the wingbeat frequency of 234±13.9 Hz. Higher-order normal modes of the wing tended to incorporate nodal lines in the chordwise direction of the trailing edge, suggesting that their mode shape did not strongly resemble wing deformation during flapping flight. These results support the stiff element hypothesis for Apis mellifera.

Excessive and prolonged intake of antibiotics results in the emergence of antibiotic-resistant pathogenic bacterial strains. As a consequence, managing bacterial infections with currently available antibiotics is extremely challenging. In order to tackle the bacterial resistance, bacterial communication mechanism, especially bacterial quorum sensing (QS) is targeted. In agr QS system, the various gene expression involved in the secretion of virulence factors can be attenuated by inhibiting the DNA-AgrA interactions. Here, we docked twenty flavonoids with previously homology modeled AgrA proteins together with PDB ID: 4G4K (template protein of the homology models) using the AutoDock tool. Out of twenty flavonoids, three flavonoids (dracorhodin, acacetin, and oroxylin A) exhibited promising binding free energies (<-9.00 kcal/mol). We also performed a normal mode analysis to check the stability of docked complexes. The best-docked complexes are stable as indicated by normal mode analyses. The best three flavonoids (dracorhodin, acacetin, and oroxylin A) possess desirable drug-likeness attributes. Hence, these compounds can act as novel AgrA inhibitors [ABSTRACT FROM AUTHOR]

Axisymmetric oscillations of fluid in a rapidly rotating whole sphere immersed in a magnetic field can be supported by the elastic tension of the magnetic field lines. This special class of Alfvén waves is largely geostrophic (invariant along the rotation axis) and describes a set of normal modes that has been extensively studied in the ideal, lossless case, a limit in which regular solutions do not exist when the background magnetic field is axisymmetric. We study the geophysically relevant limit with parameters such that magnetic diffusion plays a realistic role appropriate to the Earth's core, by choosing a Lundquist number Lu appropriately. We demonstrate for the first time the existence of normal modes in the presence of an axisymmetric background field, and obtain eigenfrequencies and decay rates that lead us to deduce quality factors Q for these modes for two simple background fields of dipole and quadrupole parity. Two scaling behaviours of Q are seen depending on the background field and normal modes' frequency, one scaling as Lu1/2 and another as Lu , so that likely Q>10 in the core of the Earth. A one-dimensional theory is presented that is able to capture the frequencies of oscillation quite accurately. [ABSTRACT FROM AUTHOR]

Realistic sound effect synchronized with visual rendering can greatly improve the immersive sense of a user in virtual reality (VR). Prior work focuses on sound propagation in air without considering the characteristics of underwater, thus cannot be directly extended for underwater scenarios. This paper proposes a novel method for simulating sound propagation in underwater scenes. We combine the normal mode method in oceanography with an improved ray tracing method to effectively calculate underwater sound propagation. A normal mode method is adapted for sound pressure calculation in the low-frequency domain. In the high-frequency domain, by considering the characteristics of underwater, we propose a threshold-based improved ray tracing method to compute the impulse response, bringing results closer to real values at higher efficiency. We sample the possible listener positions and use backward ray tracing to perform interpolation and extrapolation at runtime. Our simulation results are realistic at interactive rendering rates for scenes with moving sources. To the best of our knowledge, this is the first time that a sound propagation model tailored for underwater environment is presented in the field of VR. Various experiments in underwater scenes validated our method. [ABSTRACT FROM AUTHOR]

This paper's main objective is to study the two-dimensional deformation of the thermoelastic micro-elongated solid with the effect of initial stress on the model of dual-phase-lag and the theory of Lord and Shulman (L-S). The interface of the elastic half-space and the thermoelastic micro-elongated half-space is utilized to apply mechanical force. The solution has been made using the normal mode analysis method. For aluminum epoxy, numerical simulations are done and graphically presented to demonstrate the presence and complete absence of initial stress on the various physical quantities. [ABSTRACT FROM AUTHOR]

Matched Field Processing (MFP) is one of the most famous algorithms for source detection and underwater localization. Traditional MFP relies on a match between the received signal at the hydrophone array and a replica signal, which is constructed using Green's Function, then by scanning the space in range and depth to provide an estimation of source position in shallow water and deep water. Different environment models relying on Green's function exist for constructing the replica signal; this includes normal modes in a shallow water waveguide, the Lloyd-Mirror Pattern, and the Image model. Using the proposed estimation algorithm, here, an analytical Lloyd-Mirror model is developed based on the reflection from the target surface for a case where a target is located in the source signal propagation path. So, in this paper, a new underwater acoustic target localization algorithm using the generalized Lloyd-Mirror Pattern is presented. This idea is verified using an acoustic data from a 2019 underwater communication trial in Grand Passage, Nova Scotia, Canada. [ABSTRACT FROM AUTHOR]

The molecular mobility of poly (propylene glycols) with molecular weights between 2000 and 18,200 g mol−1 was studied in the amorphous solid state, in the region of the glass transition and in the rubbery state; the experimental techniques used were differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC). It was found that the glass transition temperature increases slightly with MW and tends to a limit value: TgDSC = −67°C, TgTSDC = −73°C. The different types of molecular mobility were analyzed: below Tg the secondary relaxations, and above this temperature the normal mode, were characterized in detail using TSDC; in the glassy transformation region, around Tg, the main relaxation was analyzed by both DSC and TSDC. It was found the dynamic fragility, m, behaves as independent of the molecular weight in the studied range: mDSC = 74 and mTSDC = 92. The TSDC results also show that, without influencing the kinetics of the segmental relaxation, the increase in molecular weight slows down the chain relaxation. [ABSTRACT FROM AUTHOR]

Algorithms working in mode space instead of directly matching the received complex sound pressure were developed to improve computational efficiency and robustness, but these algorithms may be inconvenient to apply in practice because manual operations are often inevitable when performing modal filtering. Based on a phase-matched filter, an imperfect matching scheme named the modal phase based matched impulse response (MP-MIR) is proposed to estimate the source range rapidly and conveniently with a single hydrophone. The field to be matched is still the received complex sound pressure. The replica field is a sum of several “phase” modes, which can be efficiently and conveniently synthesized merely with the horizontal wavenumbers of normal modes and the source–receiver range. The effectiveness of the proposed MP-MIR was demonstrated in localizing 84 emissions along a weakly range-dependent track at ranges of 2.54–20 km in the South China Sea. Although it was found, from cross-correlation coefficients, that the received signals showed strong variation even between adjacent emissions, MP-MIR outperformed the classical matched impulse response (MIR) with a lower standard deviation in most cases, demonstrating good robustness and potential for practical applications.