Wave Width Research Articles

Improved design of optical-microforce sensor with high thermal-mechanical stability for insulation charge ellipsometer testing application

Optical-microforce sensor is the core of the sensing module for the insulation charge ellipsometer testing, whose thermal-mechanical stability directly affects the charge measurement reliability. In this paper, based on molecular simulation, the improved design for SU-8 photoresist-based optical-microforce sensor is proposed. It is found that carboxyl-functionalized carbon nanotube/SU-8 photoresist composite system with 75 % cross-linking index possesses the comparatively better thermal-mechanical stability. Then, based on the photolithography process, modified and unmodified optical-microforce sensors are prepared. Meanwhile, the thermal-mechanical stability is evaluated from the experimental perspective. The experiment is consistent with the molecular simulation, showing that compared with the unmodified optical-microforce sensor with measurement fluctuation of 17.6 %, the modified sensor exhibits better thermal-mechanical stability, whose measurement fluctuation is only 5.3 % during the temperature range of 25–100 °C. Further, the optical-microforce sensor measurement performance evaluation platform is built. It is shown that the modified sensor could achieve the response to different frequency, different magnitude elastic wave and picosecond pulse width elastic wave, which could be applied in the insulation charge ellipsometer testing application.

Ginzburg–Landau equations involving different effects and their solitary waves

Ginzburg–Landau equations describe a wide range of phenomena involving superconductivity, superfluidity, etc. In the present paper, Ginzburg–Landau equations involving distinct laws are considered, and as a consequence, their solitary waves in the presence of perturbation terms are formally derived using the Kudryashov method. The effect of Kerr and parabolic laws on the dynamics of solitary waves is examined in detail. The outcomes of the current paper present suitable ways to control the width and amplitude of solitary waves. The authors believe that the results reported in the current study will contribute significantly to studies related to Ginzburg–Landau equations with distinct laws.

Fano resonances in gated phosphorene junctions

Fano resonances appear in plenty of physical phenomena due to the interference phenomena of a continuum spectrum and discrete states. In gated bilayer graphene junctions, the chiral matching at oblique incidence between the spectrum of electron states outside the electrostatic barrier and hole bound states inside it gives rise to an asymmetric line shape in the transmission as a function of the energy or Fano resonance. Here, we show that Fano resonances are also possible in gated phosphorene junctions along the zigzag direction. The special pseudospin texture of the charge carriers in the zigzag direction allows at oblique incidence the interference phenomena of the spectrum of electron states outside the electrostatic barrier with hole bound states inside it, giving rise to an asymmetric Fano line shape in the transmission. Due to the energy scale of the electrostatic barriers in phosphorene ultra thin barriers are required to observe the Fano resonance phenomenon. The preservation of the pseudospin texture with the closing of the phosphorene band gap opens the possibility to observe Fano resonances in smaller and wider electrostatic barriers. The asymmetric Fano line shape is susceptible to the transverse wave vector, the strength and width of the electrostatic barrier. Additionally, the conductance shows a characteristic mark in the position where the Fano resonances take place. The similarities and differences with respect to Fano resonances in bilayer graphene are also addressed.

Evaluating the predictive efficacy of real-time 3D echocardiography in cardiac resynchronization therapy

BackgroundThe aim of this study is to assess the predictive efficacy of real-time three-dimensional echocardiography (RT-3DE) and QRS wave duration in determining the response to cardiac resynchronization therapy (CRT) and assessing left ventricular systolic function pre- and post-CRT device implantation.MethodA total of 51 patients with heart failure undergoing CRT at the Second Affiliated Hospital of Nantong University between January 1, 2013, and October 31, 2020, were enrolled in this study. Traditional two-dimensional echocardiography and RT-3DE were performed pre and post-CRT, with QRS wave width data from electrocardiograms and additional clinical information collected. Patients were categorized into CRT responder (n = 36) and CRT non-responder (n = 15) groups based on their response to CRT device implantation. Comparative analyses were conducted on the general characteristics of both groups, as well as the predictive efficacy of RT-3DE and QRS wave width for CRT responsiveness and left ventricular systolic function. Data on the standard deviation (Tmsv16-SD, Tmsv12-SD, Tmsv6-SD) and maximum difference (Tmsv16-Dif, Tmsv12-Dif, Tmsv6-Dif) of left ventricular end-systolic volume (LVESV) at segments 16, 12, and 6, as well as QRS wave width, were collected and analyzed.ResultsThe indicators Tmsv6-Dif, Tmsv12-Dif, Tmsv16-Dif, Tmsv6-SD, Tmsv12-SD, Tmsv16-SD, and QRS wave width exhibited significantly higher values in the CRT responder group when compared to the CRT non-responder group (P < 0.05). Among these, Tmsv16-SD demonstrated superior predictive performance for post-CRT response, with a sensitivity of 88.9%, specificity of 80.0%, and a diagnostic cut-off value of 6.19%. This predictive capability exceeded that of the conventional indicator, QRS wave width.ConclusionRT-3DE enables accurate prediction of post-CRT patient response and significantly facilitates quantitative assessment of CRT therapy efficacy.

Wind Speed Shear Exponent: Effects of Sea Surface Roughness in Terms of Spectral Bandwidth

Abstract This note presents results on the wind speed shear exponent demonstrating the effects of the sea surface roughness in terms of the spectral bandwidth of ocean surface waves. The wind speed shear exponent is obtained by combining the logarithmic mean wind speed profile and the power law mean wind speed profile containing the sea surface roughness as a parameter, as used by Viselli et al. (2022, “LiDAR Measurements of Wind Shear Exponents and Turbulence Intensity Offshore the Northeast United States,” ASME J. Offshore Mech. Arct. Eng., 144(4), p. 042001). In the present article, the sea surface roughness is given in terms of the spectral bandwidth as presented by Zhao and Li (2024, “Dependence of Drag Coefficient on the Spectral Width of Ocean Waves,” J. Oceanogr., 80(2), pp. 129–143). Examples of results representing realistic wave conditions are provided. The results should be useful demonstrating how the wind speed shear exponent can be estimated using the spectral bandwidth, which is a frequently used parameter to characterize wave conditions.

Six-wave interaction in multimode waveguides with Kerr nonlinearity with allowance for the Gaussian structure of pump waves

The quality of wavefront conjugation in the case of six-wave interaction in two-dimensional multimode waveguides with Kerr nonlinearity is analyzed under the condition that one of the pump waves excites a zero waveguide mode and the amplitude distribution of the other pump wave at the waveguide end facet varies according to the Gauss law. It is shown that in a waveguide with infinitely conducting walls, the half-width of the modulus of the point spread function of a six-wave radiation converter is completely determined by the transverse size of the waveguide and weakly depends on the width of the Gaussian pump wave. In a parabolic-index profile waveguide, a decrease in the width of the Gaussian pump wave at the waveguide ends commonly leads to a monotonic decrease in the half-width of the point spread function modulus.

Exact solutions of the nonlinear space-time fractional Schamel equation

This study focuses on the nonlinear space-time behavior of a plasma system made up of electrons, positive ions, and negative ions using the fractional Schamel (FS) equation. The main goal is to find exact solutions to the nonlinear FS equation by applying the extended hyperbolic function (EHF) method. The study examines how the fractional order affects the phase velocity, amplitude, and wave width of solitary wave solutions. Different exact solutions were found based on various values of the fractional order. Graphical representations are included to show the physical properties of these solutions. Overall, the results demonstrate that the EHF method is effective and reliable for finding exact solutions to the nonlinear FS equation.

A global springback compensation method for manufacturing metallic seal ring with complex cross-section and submillimeter precision

The fabrication of complex thin-walled components with irregular cross-sectional geometries often necessitates multi-pass forming processes. The springback phenomena at the microscale level contribute significantly difficulty to the precise control of geometrical accuracy for such components. To achieve submillimeter precision control of micro features in metal seal rings, this research proposed a global springback compensation method to facilitate the attainment of the optimized surfaces of dies. Through the analysis of changes in cross-sectional shape, stress distribution and bending moment in the multiple stages, several partition points were set up to divide the cross-section into four zones. For a partitional control of the manufactured surface, the compensation magnitudes for each segment are determined by iteratively refining the compensation factors using the secant method. The iteration of compensation factors is based on the deviation of dimensions measured by finite element simulation, which greatly saves experimental costs. The experimental results indicate that the predictive dimensional alterations by the global compensation agree with the experimental ones exhibiting a maximum error of less than 3 %. Furthermore, the springback behavior during the unloading and trimming stages coupling caused a dimensional error of 14.9 % for the wave width and 8.3 % for the peak width. Following the application of coupled compensation through two iterations, a distinct decrease in the relative average errors of springback values for both part width and peak width, achieving reductions to 2.4 % and 0.6 %, respectively. Compared to the traditional single springback compensation technique, the global compensation strategy effectively mitigates the out-of-tolerance issues induced by the trimming process.

Double wavefront reversal during six-wave interaction on Kerr nonlinearity in a waveguide with infinitely conducting surfaces

Background. Generation of a wave with a double reversed wavefront in multimode waveguides increases the efficiency of six-wave radiation converters and expands the possibilities of its use in adaptive optics problems and the conversion of complex spatially inhomogeneous waves. Aim. The quality of double wavefront reversal during six-wave interaction in a waveguide with infinitely conducting surfaces with Kerr nonlinearity is analyzed for the ratio of the wave numbers of the pump waves equal to 2 and 0,5, and the condition that one of the pump waves excites the zero mode of the waveguide, and the amplitude distribution of the other pump wave excites the edges of the waveguide are described by a Gaussian function. Methods. The influence of pump wave parameters on the half-width and contrast of the amplitude modulus of the object wave was studied using numerical methods. A wave from a point source located on the front face of the waveguide was used as a signal wave. Results. The dependences of the half-width and contrast of the amplitude modulus of the object wave on the ratio between the width of the waveguide and the width of the Gaussian pump wave are obtained. Conclusion. It is shown that the maximum change in the characteristics of a wave with a double reversed wavefront is observed when the width of the Gaussian pump waves changes in the range from 0,3 to 2 half-widths of the waveguide.

Several nonlinear waves in spin quantum electron-positron plasmas

By using the reductive perturbation method, we obtained a nonlinear Schrödinger equation considering spin properties for a magnetized electron-positron plasmas. Several nonlinear wave were studied. The results indicate that various types of nonlinear waves exist in a magnetized electron-positron plasmas and they are spatially localized in both parallel and vertical directions to the external magnetized field direction. Additionally, the dependence of the wave amplitudes, wave width in both direction, group velocity of the envelop wave and the phase velocity of the background waves for these kinds of the nonlinear waves on the system parameters are all given in the present paper.

Change in RhoGAP and RhoGEF availability drives transitions in cortical patterning and excitability in Drosophila

Actin cortex patterning and dynamics are critical for cell shape changes. These dynamics undergo transitions during development, often accompanying changes in collective cell behavior. Although mechanisms have been established for individual cells' dynamic behaviors, the mechanisms and specific molecules that result in developmental transitions invivo are still poorly understood. Here, we took advantage of two developmental systems in Drosophila melanogaster to identify conditions that altered cortical patterning and dynamics. We identified a Rho guanine nucleotide exchange factor (RhoGEF) and Rho GTPase activating protein (RhoGAP) pair required for actomyosin waves in egg chambers. Specifically, depletion of the RhoGEF, Ect2, or the RhoGAP, RhoGAP15B, disrupted actomyosin wave induction, and both proteins relocalized from the nucleus to the cortex preceding wave formation. Furthermore, we found that overexpression of a different RhoGEF and RhoGAP pair, RhoGEF2 and Cumberland GAP (C-GAP), resulted in actomyosin waves in the early embryo, during which RhoA activation precedes actomyosin assembly by ∼4 s. We found that C-GAP was recruited to actomyosin waves, and disrupting F-actin polymerization altered the spatial organization of both RhoA signaling and the cytoskeleton in waves. In addition, disrupting F-actin dynamics increased wave period and width, consistent with a possible role for F-actin in promoting delayed negative feedback. Overall, we showed a mechanism involved in inducing actomyosin waves that is essential for oocyte development and is general to other cell types, such as epithelial and syncytial cells.

Aberration correction by polynomial approximation for synthetic aperture ultrasound imaging

AbstractBackgroundPreviously, there has been some work in the field of optical imaging on phase compensation by employing Legendre polynomials as an expansion of the phase function, and this seems to be an appealing unstudied area in the field of ultrasound imaging.PurposeThe paper is devoted to solving one of the problems of enhancing the authenticity of diagnostics data obtained in ultrasound visualization systems and presents a novel approach to aberration correction, which ensures a reliable eliminating of phase distortions. The novelty of the proposed approach consists in the use of the decomposition of the wave front by Legendre polynomials to approximate aberrations of the phase front of ultrasonic waves propagating through distorting layers.MethodsThe phase aberrations are corrected using a single sector probe that captures echoes in synthetic aperture mode. The proposed method approximates the changes in the wave front by means of the Legendre polynomials. The performance was investigated by placing a 13‐mm‐wide ultrasonic probe with 64 elements operating at 2 MHz on the surface of a commercial quality control phantom ATS Model 539 through a distorting layer. The following metrics were measured: peak value, root mean square (RMS), full width at half maximum (FWHM), contrast‐to‐noise ratio (CNR). During the experiments, three different aberrators were used interchangeably as distorting layers, two of which were made of photopolymer resin with RMS values of 39 and 97 ns and a speed of sound close to that of a human temporal bone tissue, and the third was an ex vivo human temporal bone with the RMS value of 44 ns. To test the correction, three regions inside the phantom were examined. Two‐sided nonparametric Wilcoxon rank‐sum test was used for assessing the statistical significance. The significance level for this study was set at α ≤ 0.05. To counteract the problem of multiple comparisons, the p‐values were adjusted by the Holm–Bonferroni correction method.ResultsThe statistically significant results have demonstrated the possibility of increasing peak intensity value up to 3.08 times, reducing the RMS width and FWHM of the intensity angular distribution down to 60% and 82%, respectively, and increasing CNR up to 2.12 times by using the proposed phase distortion correction method, compared with the case without correction. The results show that the method can be used as an effective aberration correction technique for all tested regions inside the phantom and distorting layers. Its usage allowed correcting up to 97% of the aberrations caused by the ex vivo temporal bone model.ConclusionThe results show that the usage of the proposed method for aberration correction can successfully increase the intensity and reduce the angular width of the ultrasound wave scattered by the point targets inside the phantoms. The method works with different distorting layers and is capable of correcting phase aberrations in multiple sections of the sonogram. The limitation of the proposed method consists in the fact that it requires the use of aperture synthesis and access to raw radiofrequency data, which restricts its application in common scanners.

Pressure–temperature–time controls on shock vein formation within the Steen River impact structure

ABSTRACTThermodynamic modeling has been applied to determine pressure–temperature–time conditions leading to shock vein formation during the passage of a natural shock wave generated by hypervelocity impact. The approach is novel in considering both shock front and rarefaction pressures, as well as simultaneously forming and cooling the shock veins via two‐dimensional steady‐state conduction. Model results are tested using shock veins developed in granitic rocks that constitute the central uplift of the Steen River impact structure in Canada. Here, two variants of majoritic garnet were generated in different settings: (1) along the margins of shock veins due to pargasite and biotite breakdown (accompanied by maskelynite formation), and (2) within the originally molten shock vein matrix as newly grown crystals. We determine that during shock vein formation, the shock front pressure and wave width at the reconstructed sample location were 18 GPa and 830 m, respectively, with a dwell time of 160 ms. Intra‐vein melting at 2150°C was attained within 1 μs. Melt cooled to the solidus in 150 ms following shock front passage. Majoritic garnet formation was facilitated by the high temperatures realized within the veins as a result of frictional melting that accompanied shock loading. The calculated pressure–temperature–time (P–T–t) path provides constraints on the formation conditions of majoritic garnet at Steen River. The model results independently support previously determined P–T conditions based on mineral stability fields. The vein margin garnets (35–39 mole% majorite) and maskelynite formed first under higher P–T conditions for a longer duration (36 ms). The matrix garnets (11–22 mole% majorite) crystallized from melt under lower P–T conditions and for a shorter duration (22 ms). Our results indicate that shock pressure alone should not be used as a basis for shock classification. Instead, the interplay between pressure and temperature with time and the duration of shock immersion (dwell) must be considered.

Small amplitude solitary electron acoustic wave for hot electrons taking regularized kappa distribution

AbstractThe properties of small‐amplitude solitary electron acoustic waves in a plasma where the hot electrons take regularized kappa distribution are investigated via the reductive perturbation method. It is found there only exists the sup‐electron‐acoustic rarefactive soliton, the electron acoustic velocity is modified by the regularized kappa distribution. The amplitude and width of the electron acoustic soliton decrease monotonously with the increase of the exponential cutoff parameter of hot electrons. But they vary with respect to the spectral index non‐monotonously. As to the observed parameters in the Earth's inner magnetosphere, the speed, electric field strength, and the width of solitary electron acoustic wave are comparable with the observations.

Simulation of optomechanical interaction of levitated nanoparticle with photonic crystal micro cavity.

We propose and analyze theoretically a promising design of an optical trap for vacuum levitation of nanoparticles based on a one-dimensional (1D) silicon photonic crystal cavity (PhC). The considered cavity has a quadratically modulated width of the silicon wave guiding structure, leading to a calculated cavity quality factor of 8 × 105. An effective mode volume of approximately 0.16 μm3 having the optical field strongly confined outside the silicon structure enables optical confinement on nanoparticle in all three dimensions. The optical forces and particle-cavity optomechanical coupling are comprehensively analyzed for two sizes of silica nanoparticles (100 nm and 150 nm in diameter) and various mode detunings. The value of trapping stiffnesses in the microcavity is predicted to be 5 order of magnitudes higher than that reached for optimized optical tweezers, moreover the linear single photon coupling rate can reach MHz level which is 6 order magnitude larger than previously reported values for common bulk cavities. The theoretical results support optimistic prospects towards a compact chip for optical levitation in vacuum and cooling of translational mechanical degrees of motion for the silica nanoparticle of a diameter of 100 nm.

Observation of non-planar dust acoustic solitary wave in a strongly coupled dusty plasma

The nonlinear evolution and propagation of a stable dust acoustic solitary wave (DASW) in a non-planar geometry is investigated here. The experiment is performed in a strongly coupled dusty plasma consisting of monodisperse micrometer sized particles levitated in the sheath of a capacitively coupled radio frequency argon plasma. The non-planar waves are generated with the help of a cylindrical conducting exciter pin placed at the center of the homogeneous dust cloud. A negative excitation pulse is used to create a dust void and a dust density perturbation simultaneously around the exciter. From the edge of the void, the density perturbation propagates as a nonlinear (cylindrical) non-planar DASW. The characteristics of the solitary wave are measured using image analysis of the recorded video of wave propagation. The numerical solution of the modified Korteweg–de Vries equation with an additional term to take care of the non-planar geometry is compared with the experimental observation. The wave amplitude and width are measured as a function of time and compared with the theoretical predictions.

Dependence of drag coefficient on the spectral width of ocean waves

The sea-surface roughness or drag coefficient is ascribed to the effect of various components of ocean waves. Many studies have been focused on the investigation of the dependence of drag coefficient on sea states that are usually denoted by wave age. However, no universally accepted relationship has been obtained up to now and the results are significantly scattered or even contradicted. We reviewed the parameterizations of sea-surface roughness as a function of wave age, and found that the phase speed at spectral peak cp is an important parameter to characterize the drag coefficient. For the same wave age, drag coefficient increases with increasing cp. Contrary to the traditional concept, the older waves with greater cp possesses higher sea-surface roughness for the same wind speed because more wave components participate the air–sea interaction and intensify the wind stress. With the buoy meansurements and the theory of equilibrium range of wind waves, we estimated fricition velocity and proposed that the frequency bandwidth and spectral width of the wave spectrum are more suitable parameters than the traditional wind speed and wave age to be used to parameterize drag coefficient. This study provides a new way to estimate wind stress through the reliable spectra of ocean waves.

Theoretical study of influence of laser pulse chirp on terahertz emission characteristics of gas induced by two-color laser field

With the development of terahertz (THz) wave research, the demand for controllable THz sources is increasing. How to obtain the regulated THz waves has been one of the research hotspots and key problem in the field of THz science. There have been researches in which the resulting THz wave is modulated by changing the wavelength, relative phase, energy, or chirp of the laser produced by a two-color laser. In this work, we establish a three-dimensional theoretical model of THz wave generation and subsequent propagation induced by two-color laser. And we investigate the influence of chirp modulation of different laser on THz wave by chirp modulation of the fundamental wave (FW) and the second harmonic wave (SHW) of two-color laser, including THz wave amplitude, THz wave center frequency and spectrum width, and analyze the physical mechanism of related phenomena. At the same time, the effects of different orders of magnitudes of laser chirp parameters (femtosecond and picosecond) and initial phase of laser pulse on THz wave parameters are also studied. The results are shown below. 1) In the two-color laser, the chirp of FW mainly affects the shape of THz wave when the initial phase is unchanged. The chirp modulation of SHW can cause the amplitude of THz wave to change significantly, and affect the center frequency and spectrum width of THz waves. 2) In the case of laser pulse width of femtosecond order, 40 fs is taken as an example. When the chirp parameter is of femtosecond magnitude, the chirp parameter has a great influence on the THz wave generation efficiency of two-color laser filament. At the picosecond magnitude, the chirp parameter has a weak effect on the THz wave energy and mainly affects the phase of the THz wave. 3) The initial phase of the two-color laser can aid in chirp modulation of THz wave to optimize the energy generated. 4) The initial phase of two-color laser can assist in the process of chirped laser modulation of terahertz waves to optimize the energy generated. Our research shows that the chirp modulation, as a controllable parameter, has multiple regulation effect on the properties of radiated THz waves. The related research results provide a new idea and basis for studying the generation and regulation of THz waves.

Propagation characteristics of nonlinear dust acoustic solitary waves in complex plasma with nonthermal electrons and trapped ions

The propagation characteristics of nonlinear dust acoustic solitary waves in a complex plasma system with nonthermal electrons and trapped ions are investigate in this work. The nonlinear dispersion relation of dust acoustic waves is obtained by using the linear method, and the two-dimensional autonomous system governing the motion of nonlinear dust acoustic waves is derived by using the Sagdeev potential method. At the same time, the specific expression of the Sagdeev potential function is obtained based on the Sagdeev potential equation. The numerical simulations are used to analyze the phase portraits of the two-dimensional autonomous system, revealing the linear periodic wave orbits, nonlinear periodic wave orbits, and homoclinic orbits co-existing in the complex dusty plasma system with nonthermal electrons and trapped ions. Furthermore, from the variations of the Sagdeev potential function with different system parameters it follows that only the compressive solitary waves exist in this complex plasma system. The significant influences of various system parameters on the amplitude, width, and waveform of the nonlinear dust acoustic solitary wave in the complex plasma system are discussed in detail. The results demonstrate that the Mach number, the nonthermal electrons and trapped ions, undisturbed dust particle number density, temperature, and charge have important effects on the propagating characteristics of the nonlinear dust acoustic solitary waves in a complex plasma with nonthermal electrons and trapped ions.

Performance evaluation of an integrated heatsink and thermoelectric module by two-way coupled numerical analysis

Experimentally validated numerical models contribute to the literature and provide clues to researchers. In recent years, thermoelectric coolers have come to the fore as an alternative to existing cooling systems. The effect of the geometric parameters of a heat sink (wave amplitude, wave width, and wavelength) and the parameters of a thermoelectric module (conductor thickness, solder thickness, and the leg lengths of P and N type) are investigated parametrically. The numerical study has been carried out by coupled CFD and Thermal Electric tools and validated with experimental data. The three-dimensional model has consisted of a heat sink with converging diverging channels integrated with a thermoelectric module. It has been investigated by the numerical model how the specified design parameters of the heat sink and thermoelectric module affect the cooling performance of the fluid flowing through the heat sink. Evaluation of the results has been made according to the temperature of the fluid out of the heat sink, the bottom temperature of the heat sink, the current produced on the thermoelectric module and the heat transfer coefficient. The results showed that the parameters have an effect on the thermal performance, but their effect on the current change is limited.