Amplitude Distribution Research Articles

Structure of heavy mesons in the light-front quark model

We investigate the structure of ground-state heavy mesons within the light-front quark model, utilizing wave functions derived from the single Gaussian ansatz (SGA) and the Gaussian expansion method (GEM). By performing a χ2 fit to static properties such as mass spectra and decay constants, we determine the model parameters for each approach. We then compare the impacts of both methods on the light-front wave functions and structural observables. Our analysis reveals significant differences in the distribution amplitudes ϕ2;M(x) near the end points, with GEM showing enhanced amplitudes and correct asymptotic behavior ϕ2;M(x→1)∝(1−x), consistent with perturbative QCD. This end point behavior is linked to the short-range (high-momentum) wave function governed by color Coulomb interaction and relativistic kinematics. GEM accurately reproduces a power-law damping ψ0(k→∞)∝1/k⊥2, aligning with perturbative QCD predictions. Furthermore, the electromagnetic form factors of pseudoscalar mesons in the low-Q2 region fall off faster with GEM than with SGA. Overall, while both methods adequately describe static properties, GEM provides a more accurate description of structural properties, being more sensitive to details and asymptotic behaviors. Published by the American Physical Society 2024

High-quality phase imaging by phase-shifting digital holography and deep learning

Quantitative phase imaging (QPI) technology is widely used in biomedical imaging and other fields because it can realize exact imaging for transparent phase-type samples, which is of great research significance. The complex amplitude distribution of the object wave obtained by phase-shifting digital holography (PSDH) reproduction can provide phase information for QPI, but its existence of phase wrapping and other problems limits its practical application. Although the traditional phase unwrapping algorithm provides a solution, it has problems such as low unwrapping accuracy or long time running. To solve these problems in QPI, a high-quality phase imaging (HQPI) method by PSDH and deep learning (DL) is proposed, where QPI is achieved by extracting the unknown phase shift using a generalized non-iterative phase shift extraction algorithm and unwrapping the wrapped phase by a DL network. Both numerical simulations and optical experiments verify the feasibility of the method. By comparing with the traditional phase unwrapping algorithm, it is demonstrated that the DL unwrapping method has higher unwrapping accuracy and more efficiency. The results show that the method of HQPI is capable of realizing comparatively fast and accurate QPI.

Mixture texture model with weighted generalized inverse Gaussian distribution for target detection

With the improvement of radar resolution, the amplitude distribution of sea clutter has begun to exhibit significant heavy-tailed characteristics. Existing models for sea clutter amplitude distribution do not sufficiently solve this problem, which results in a diminished target detection probability in two-step generalized likelihood ratio test (GLRT) based target detectors. To address this issue and to enhance the radar target detection capabilities, we propose a new compound-Gaussian clutter model based on a weighted mixture of generalized inverse Gaussian distributions to model the texture. The CG-WGIG model demonstrates greater flexibility and effectively captures the characteristics of sea clutter amplitude distributions with heavy tails, thus affording a better fit. We combine this model with the two-step GLRT criterion to propose a GLRT detector endowed with a weighted generalized inverse Gaussian texture (GLRT-WGIG), specifically tailored for detecting range-spread targets (RSTs). We have conducted a rigorous mathematical proof to demonstrate that the constant false alarm rate (CFAR) characteristic of the proposed GLRT-WGIG detector is independent of the covariance matrix, thereby ensuring its robustness in various operational scenarios. Using measured data, we demonstrate that the proposed model and detector are flexible and outperform the existing methods in terms of fitting and detection performance, where we obtain a mean 12.02% MSE of fitting performance promotion.

Microscopic parametrization of the near threshold oscillations of the nucleon time-like effective electromagnetic form factors

We present an analysis of the recent near threshold BESIII data for the nucleon time-like effective form factors. The damped oscillation emerging from the subtraction of the dipole formula is treated in non-perturbative-QCD, making use of the light cone distribution amplitudes expansion. Non-perturbative effects are accounted for by considering Q2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q^2$$\\end{document}-dependent coefficients in such expansions, whose free parameters are determined by fitting to the proton and neutron data. Possible implications and future analysis have been discussed.

High performance and compact antenna with new scheme for broadband circular polarisation applications

ABSTRACT In this research paper, the authors propose a unique broad-band circularly polarised antenna design with a sequentially rotated feed network intended for applications in the WiMAX IEEE 802.16, C-band, and ITU-R F386.9 bands. A sequential feeding approach utilising transmission lines with varying impedance properties and lengths has been utilised to properly stimulate the amplitude and phase distribution of each radiation element. To facilitate the rotation of the surface current distribution on the ground plane and further improve impedance matching, four L-shaped slits have been inserted into each corner of the ground plane along with a pair of mirrored slits of identical geometry within the antenna ground plane. The individual antenna element achieves an impedance bandwidth between 5–6.8 GHz and a 3 dB axial ratio bandwidth from 5.1–6.6 GHz. To additionally advance the radiation performance, the elements are configured into a 2 × 2 antenna and are interconnected utilising a sequentially rotated feeding network to attain broader axial ratio and impedance bandwidths. A key benefit of the implemented feed network is the minimisation of coupling effects between elements. To significantly increase the performance metrics of the antenna with limited increase to its physical size, electromagnetic band gap structures were incorporated as a one-dimensional lattice between the radiating elements. For the resulting antenna, an axial ratio bandwidth from 4.19 to 6.8 GHz (48%) and an impedance bandwidth spanning 2.9 to 9.8 GHz (102%) are achieved. The peak gain of the antenna is 11.2 dBic.

Individualized time windows enhance TMS-EEG signal characterization and improve assessment of cortical function in schizophrenia.

Transcranial magnetic stimulation and electroencephalography (TMS-EEG) recordings are crucial to directly assess cortical excitability and inhibition in a non-invasive and task-free manner. TMS-EEG signals are characterized by TMS-evoked potentials (TEPs), which are employed to evaluate cortical function. Nonetheless, different time windows (TW) have been used to compute them over the years. Moreover, these TWs tend to be the same for all participants omitting the intersubject variability. Therefore, the objective of this study is to assess the effect of using different TWs to compute the TEPs, moving from a common fixed TW to more adaptive individualized TWs. Twenty-nine healthy (HC) controls and twenty schizophrenia patients (SCZ) underwent single-pulse (SP) TMS-EEG protocol. Firstly, only the HC were considered to evaluate the TEPs for three different TWs in terms of amplitude and topographical distribution. Secondly, the SCZ patients were included to determine which TW is better to characterize the brain alterations of SCZ. The results indicate that a more individualized TW provides a better characterization of the SP TMS-EEG signals, although all of them show the same tendency. Regarding the comparison between groups, the individualized TW is the one that provides a better differentiation between populations. They also provide further support to the possible imbalance of cortical excitability/inhibition in the SCZ population due to its reduced activity in the N45 TEP and greater amplitude values in the N100. Results also suggest that the SCZ brain has a baseline hyperactive state since the TEPs of the SCZ appear earlier than those of the HC.

Lightcone and quasi distribution amplitudes for light octet and decuplet baryons

We present a comprehensive investigation of leading-twist lightcone distribution amplitudes (LCDAs) and quasi distribution amplitudes (quasi-DAs) for light octet and decuplet baryons within large momentum effective theory. In LaMET, LCDAs can be factorized in terms of a hard kernel and quasi-DAs that are defined as spatial correlators and calculable on Lattice QCD. To renormalize quasi-DAs and eliminate the singular terms ln(μ2zi2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\mu}^2{z}_i^2 $$\\end{document}) in them, which undermine the efficacy in perturbative expansion, we adopt a hybrid renormalization scheme that combines the self-renormalization and ratio scheme. Through self-renormalization, we eliminate UV divergences and linear divergences at large spatial separations in quasi distribution amplitudes without introducing additional nonperturbative effects. By taking a ratio with respect to the zero-momentum matrix element, we effectively remove UV divergences at small spatial separations. Under the hybrid renormalization scheme, we calculate the hard kernels up to one-loop accuracy. It turns out that only four different hard kernels are needed for all leading-twist LCDAs of octet and decuplet baryons. These results are crucial for the lattice-based exploration of the LCDAs of a light baryon from the first principle of QCD.

A prediction method for railway-induced vibrations in building structures using modal properties in limited modes

This paper proposes a prediction method to estimate vibrations in building structures induced by to-be-constructed railways. The method derives modal equations of motion for building modeling by using the natural frequencies in limited modes, the corresponding damping ratios and mode shapes at selected locations. The participation vector for input ground motions is approximated by the corresponding mode shapes. Those modal properties can be obtained from ambient vibration testing, and hence the modeling does not require design documents to construct the mass, damping and stiffness matrices. The railway-induced motions at the column bases can be estimated priorly, and the dynamic responses at the selected locations are subsequently predicted by mode superposition. The fundamental characteristics of the proposed prediction method are studied by numerical simulations. The simulation result shows high participation-vector approximation accuracy when using few lower mode shapes at few locations; Higher modes exhibit more complicated mode shape amplitude distribution, and thus mode shapes at more locations are required for the sufficient approximation accuracy; Compared with seismic response calculation in the horizontal directions where few lower modes are sufficient, higher modes are required for satisfactory prediction accuracy. The method provides an alternative approach for predicting railway-induced vibrations and is helpful when design documents of the objective building are unavailable. The findings from the simulation provide guidance to the measurement-point design and the objective modes to identify in the implementation of the proposed method.

A New Electric Arc Furnace Model Based on Current Waveform Synthesis From Distributions of DFT Amplitudes and Power System Frequency

A New Electric Arc Furnace Model Based on Current Waveform Synthesis From Distributions of DFT Amplitudes and Power System Frequency

The vitals for steady nucleation maps of spontaneous spiking coherence in autonomous two-dimensional neuronal networks

Thin pancake-like neuronal networks cultured on top of a planar microelectrode array have been extensively tried out in neuroengineering, as a substrate for the mobile robot’s control unit, i.e., as a cyborg’s brain. Most of these attempts failed due to intricate self-organizing dynamics in the neuronal systems. In particular, the networks may exhibit an emergent spatial map of steady nucleation sites (“n-sites”) of spontaneous population spikes. Being unpredictable and independent of the surface electrode locations, the n-sites drastically change local ability of the network to generate spikes. Here, using a spiking neuronal network model with generative spatially-embedded connectome, we systematically show in simulations that the number, location, and relative activity of spontaneously formed n-sites (“the vitals”) crucially depend on the samplings of three distributions: (1) the network distribution of neuronal excitability, (2) the distribution of connections between neurons of the network, and (3) the distribution of maximal amplitudes of a single synaptic current pulse. Moreover, blocking the dynamics of a small fraction (about 4%) of non-pacemaker neurons having the highest excitability was enough to completely suppress the occurrence of population spikes and their n-sites. This key result is explained theoretically. Remarkably, the n-sites occur taking into account only short-term synaptic plasticity, i.e., without a Hebbian-type plasticity. As the spiking network model used in this study is strictly deterministic, all simulation results can be accurately reproduced. The model, which has already demonstrated a very high richness-to-complexity ratio, can also be directly extended into the three-dimensional case, e.g., for targeting peculiarities of spiking dynamics in cerebral (or brain) organoids. We recommend the model as an excellent illustrative tool for teaching network-level computational neuroscience, complementing a few benchmark models.

Model selection techniques for seafloor scattering statistics in synthetic aperture sonar images of complex seafloors

AbstractIn quantitative analysis of seafloor scattering measurements, it is common to model the single‐point probability density function of the scattered intensity or amplitude. For more complex seafloors, the pixel amplitude distribution has previously been modelled with a mixture model consisting of two K distributions, but the environment may have more identifiable scattering mechanisms. Choosing the number of components of a mixture model is a decision that must be made, using a priori information, or using a data driven approach. Several common model selection techniques from the statistics literature are explored (the Akaike, Bayesian, deviance, and Watanabe‐Akaike information criteria) and compared to the authors' choice. Examples are given for synthetic aperture sonar data collected by an autonomous underwater vehicle in a rocky environment off the coast of Bergen, Norway, using the HISAS‐1032 synthetic aperture sonar system. The Bayesian information criterion aligned most closely with the interpretation of both the acoustic images and the plots of the probability of false alarm.

Probing the inverse moment of Bs-meson distribution amplitude via Bs→ ηs form factors

We investigate the inverse moment of the Bs-meson light-cone distribution amplitude (LCDA), denoted as λBs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{B_s} $$\\end{document} and defined within the heavy quark effective theory, through the calculation of Bs → ηs form factors. The presence of the s-quark inside the Bs-meson dictates a notable departure of approximately 20% in the λBs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{B_s} $$\\end{document} value compared to the non-strange case λBq\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{B_q} $$\\end{document}, as computed within the QCD sum rule approach, albeit with significant uncertainty. First, we compute the decay constant of the ηs-meson utilizing two-point sum rules while retaining finite s-quark mass contributions. Next, we constrain the parameter λBs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{B_s} $$\\end{document} by calculating Bs → ηs form factors within the light-cone sum rule approach, using Bs-meson LCDAs, and leveraging Lattice QCD estimates at zero momentum transfer from the HPQCD collaboration. Our findings yield λBs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{B_s} $$\\end{document} = 480 ± 92 MeV when expressing the Bs-meson LCDAs in the Exponential model, consistent with previous QCD sum rule estimate yet exhibiting a 1.5-fold improvement in uncertainty. Furthermore, we compare the form factor predictions, based on the extracted λBs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\lambda}_{B_s} $$\\end{document} value, with earlier analyses for other channels such as Bs → Ds and Bs → K.

Theoretical overview on heavy flavor physics at LHCb

Precise prediction of the heavy hadrons decay amplitudes is of great importance in the determination of the parameters of KM matrix and searching for new physics signals beyond the standard model. Due to the high accuracy of the B meson decay constants, the structure dependent QED corrections should be taken into account for B→μ+μ− decays due to the power enhancement, but this effect is numerically negligible for B→τ+τ−. The radiative leptonic decays and double radiative decays are the best channels to determine the B meson distribution amplitudes, but one should systematically deal with the power corrections to reduce the uncertainty. The heavy-to-light form factors is one of the most important nonperturbative quantities, and an improved method to improve the theoretical accuracy is to fit the form factors using combined data from Lattice and light-cone sum rules which works well at large recoil region. The power suppressed weak annihilation contribution is phenomenologically important in the nonleptonic decays, and the previously neglected hard-collinear gluon exchange diagrams have the potential to cancel the endpoint singularity arising from the hard gluon exchange. Therefore, more endeavors need to be paid to this topic.

Internal flow in sessile droplets induced by substrate oscillation: towards enhanced mixing and mass transfer in microfluidic systems

The introduction of flows within sessile droplets is highly effective for many lab-on-a-chip chemical and biomedical applications. However, generating such flows is difficult due to the typically small droplet volumes. Here, we present a simple, non-contact strategy to generate internal flows in sessile droplets for enhancing mixing and mass transport. The flows are driven by actuating a rigid substrate into oscillation with certain amplitude distributions without relying on the resonance of the droplet itself. Substrate oscillation characteristics and corresponding flow patterns are documented herein. Mixing indices and mass transfer coefficients of sessile droplets on the substrate surface are measured using optical and electrochemical methods. They demonstrate complete mixing within the droplets in 1.35 s and increases in mass transfer rates of more than seven times static values. Proof of concept was conducted with experiments of silver nanoparticle synthesis and with heavy metal ion sensing employing the sessile droplet as a microreactor for synthesis and an electrochemical cell for sensing. The degrees of enhancement of synthesis efficiency and detection sensitivity attributed to the internal flows are experimentally documented.

Effect of electromagnetic force installation method on critically reinforced interference sizes and fatigue behavior of CFRP bolted joints

AbstractThe electromagnetic force dynamic installation (DI) method of interference fit fasteners has significant advantages in improving the quality of the assembly interface of composite structure. This study aims to investigate how improving assembly interface quality may help in achieving high‐precision interference‐fit joints in composites. Single‐lap joint specimens were prepared using electromagnetic installation technique, the fatigue life and failure behaviors of the joints under different bolt‐hole clearances were measured and analyzed experimentally. In addition, a three‐dimensional finite element model was developed to predict the radial pre‐compression stresses around the hole and the progressive failure behavior of various typical damage modes in carbon fiber‐reinforced polymer induced by the interference. The results show that the critical interference range for the DI‐composite bolted structure is 1.0%–1.2%. The fatigue life of the best interference (1.0%) and the worst interference (0%, neat fit) have a difference of 36 times in amplitude. The residual stress with uniform distribution and high amplitude reduces the stress concentration of the hole wall and improves the failure evolution of the loaded hole. The contribution of this study provides vital guidance for improving the fatigue performance of CFRP bolted structures using a novel DI method.Highlights I = 1.0% is the critical damage‐enhancing interference size for dynamically installation interference fit bolts with electromagnetic forces. The residual stress amplitude introduced by the interference does not increase uniformly as the interference size increases. Excessive interference significantly reduces the uniformity and magnitude of residual stresses. Under subsequent cyclic loading, the fifth layer near the inlet and outlet of the extruded lower laminate appears to be the critical ply of extrusion deformation, and severe damage is concentrated in the critical ply of deformation. The decrease of stress amplitude and the variation of mean stress are the mechanisms of fatigue life enhancement in interference fit joints under external cyclic loading.

A mode localization inspired vibration control method based on the axially functionally graded design for beam structures

Vibration control plays a vital role in engineering structures, especially for low-frequency range, because designing structures with small dimensions makes it difficult to control large-wavelength vibrations. The present study seeks another road to realize low-frequency vibration control from the view of the real vibration responses. Similar to mode shapes, deflection modes are the main distributions of vibration amplitudes on structures in low frequency. Therefore, they are also essential vibration characteristics of structures. This paper proposes an effective passive vibration control method under both non-resonant and resonant excitations based on deflection mode theory and optimal algorithm. In fact, it is just like an axially functionally graded design for structures. The equations of motion for non-uniform beam structures are formulated by Hamilton’s principle. Firstly, a desired deflection mode is artificially designed, and the beam structure is discretely divided into subunits. Then, by adjusting the thickness or elastic modulus of each subunit to make the deflection mode of the beam coincide with that of the desired one. This process is completed by the genetic algorithm (GA). After that, by experimental and simulation analyses, the deflection mode of the optimally designed beam structures coincides with that of the desired one. Therefore, the present vibration control method is verified to be correct and effective.

Validation of Tracheal Sound-Based Respiratory Effort Monitoring for Obstructive Sleep Apnoea Diagnosis.

Background: Respiratory effort is considered important in the context of the diagnosis of obstructive sleep apnoea (OSA), as well as other sleep disorders. However, current monitoring techniques can be obtrusive and interfere with a patient's natural sleep. This study examines the reliability of an unobtrusive tracheal sound-based approach to monitor respiratory effort in the context of OSA, using manually marked respiratory inductance plethysmography (RIP) signals as a gold standard for validation. Methods: In total, 150 patients were trained on the use of type III cardiorespiratory polygraphy, which they took to use at home, alongside a neck-worn AcuPebble system. The respiratory effort channels obtained from the tracheal sound recordings were compared to the effort measured by the RIP bands during automatic and manual marking experiments. A total of 133 central apnoeas, 218 obstructive apnoeas, 263 obstructive hypopneas, and 270 normal breathing randomly selected segments were shuffled and blindly marked by a Registered Polysomnographic Technologist (RPSGT) in both types of channels. The RIP signals had previously also been independently marked by another expert clinician in the context of diagnosing those patients, and without access to the effort channel of AcuPebble. The classification achieved with the acoustically obtained effort was assessed with statistical metrics and the average amplitude distributions per respiratory event type for each of the different channels were also studied to assess the overlap between event types. Results: The performance of the acoustic effort channel was evaluated for the events where both scorers were in agreement in the marking of the gold standard reference channel, showing an average sensitivity of 90.5%, a specificity of 98.6%, and an accuracy of 96.8% against the reference standard with blind expert marking. In addition, a comparison using the Embla Remlogic 4.0 automatic software of the reference standard for classification, as opposed to the expert marking, showed that the acoustic channels outperformed the RIP channels (acoustic sensitivity: 71.9%; acoustic specificity: 97.2%; RIP sensitivity: 70.1%; RIP specificity: 76.1%). The amplitude trends across different event types also showed that the acoustic channels exhibited a better differentiation between the amplitude distributions of different event types, which can help when doing manual interpretation. Conclusions: The results prove that the acoustically obtained effort channel extracted using AcuPebble is an accurate, reliable, and more patient-friendly alternative to RIP in the context of OSA.

Entertainment performance robots application in music network classroom based on speech sensor recognition and artificial intelligence

This article designs a framework for a music online classroom, optimizing the actions of performing robots to improve their performance. Combined with speech recognition and control algorithms, the robot’s actions are adjusted in real-time based on the emotions and rhythm of the music to increase student engagement and interactivity. Music recognition adopts methods based on time–frequency analysis and pattern recognition, identifying the type of music played based on the frequency and amplitude distribution patterns in the audio signal; Voice recognition uses feature analysis and speech recognition algorithms based on speech signals to better provide targeted feedback and interaction. This article optimizes the teaching of music online classrooms and verifies the feasibility and effectiveness of using performance robots based on speech sensor recognition and artificial intelligence in music online classrooms through experiments and analysis. Performance robots can mimic the way humans perform music, including singing, playing, and dancing, helping students better understand and imitate music performances. The music online classroom application in this article combines advanced technologies such as voice sensing recognition, artificial intelligence, and performance robots, providing students with a more convenient, personalized, and efficient music learning experience.

Fatigue life prediction of metal materials under random loads based on load spectrum extrapolation

The impact of random loading on the fatigue life of mechanical components contains numerous uncertainties. This study aims to enhance the precision of life prediction by developing mean and amplitude distribution models based on the road load spectrum and extrapolating the operational load beyond the threshold value in the time domain. Additionally, it considers the influence of high cycle fatigue (HCF) and low cycle fatigue (LCF) loads on the initiation life of metal cracks. To address this, a load correction factor is introduced, and critical stresses for high and low cycle loads are proposed. Furthermore, a two-dimensional programmed load spectrum is prepared, taking into account the mean and amplitude. The accuracy and rationality of the fatigue life model are validated through examples using 45# steel and 316L, while experiments on engine support are conducted to confirm the effectiveness and accuracy of the over-threshold extrapolation life prediction method under random loading.

Transverse vibration analysis and active disturbance rejection decoupling control of rain erosion whirling arm

The transverse vibration caused by the mass eccentricity of the whirling arm and the unbalanced magnetic pull of the motor rotor is a critical factor that affects the stability and safety of the rain erosion whirling arm. To investigate the transverse vibration characteristics of the rain erosion whirling arm during operation, a four-degree-of-freedom transverse vibration model of the rotor-rain erosion whirling arm is established using the lumped mass method. The differential equation of motion of the rotor-rain erosion whirling arm, considering the influence of mass eccentricity and unbalanced magnetic pull, is then established based on the Lagrange equation. This equation is numerically solved using the Runge-Kutta algorithm to investigate the axis trajectory and amplitude distribution of the rotor-rain erosion whirling arm. To reduce the fatigue damage caused by vibration, the active disturbance rejection decoupling control method is employed. Furthermore, the parameters of the extended state observer are adjusted using pole assignment and bandwidth. The simulation results reveal that the vibration amplitude of the rotating blade can be reduced to within 0.2 mm, referring to the BSS7393 test standard. Additionally, experimental research is conducted to compare the vibration of the rain erosion whirling arm before and after implementing the active disturbance rejection decoupling control. The results demonstrate that the active disturbance rejection decoupling control method effectively suppresses the vibration of the rain erosion whirling arm, illustrating its feasibility and effectiveness for system vibration control.