Dynamic Characterization Research Articles

Coherent and Incoherent Breathing Solitons in a Bidirectional Ultrafast Thulium Fiber Laser

Mode‐locked lasers are prone to exhibit a wide range of dynamics, including the coherent dissipative soliton with high robustness or the possible emission of incoherent pulse bursts. Herein, it is proposed to expand the notion of dissipative breathing solitons to incoherent localized formation, which is illustrated experimentally by reporting original coherent and incoherent breathing solitons generated in a 2 μm bidirectional ultrafast fiber laser. A real‐time spectral characterization of the breathing soliton dynamics with different coherence is provided, highlighting salient features of the self‐organization. The switching between coherent breathing soliton and noise‐like pulse is also experimentally demonstrated, corresponding to the multiple transient decoherence and coherence recovery. High behavior similarity exists in bidirectional solitons evolution owing to the common gain and loss modulation. Numerical simulations using a discrete laser model validate the experimental findings. This research generalizes previous observations of breathing solitons made in the coherent case and opens up new possibilities for generating breathers in various dissipative systems.

Experimental study on the vibrational response and damping of short fibre/unidirectional PEEK hybrid composites

This study investigates the vibrational performance of a new generation of hybrid composites based on a short fibre core for structural dynamic applications. The dynamic characterisation was conducted through dynamic mechanical analysis (DMA) and the free vibration of a cantilever beam at different lengths. The short fibre composite exhibited a superior specific damping capacity, producing a maximum damping of 0.42. The values extracted from DMA indicated no visco-plastic contribution from the PEEK resin system, implying that the internal microarchitecture drives the material damping, with friction at the fibre/matrix interface being the primary dissipation mechanism. The hybrid laminate presented an improvement in damping performance of 39% due to the addition of the short fibre core compared to a baseline quasi-isotropic laminate of similar flexural stiffness. These findings show hybridisation’s advantages in designing structural components with improved damping performance and reduced cost for a variety of dynamic applications in industries such as automotive.

Characterization of evolutionary dynamics for drug resistance in a 3D cell culture system using cellular barcoding technology

Characterization of evolutionary dynamics for drug resistance in a 3D cell culture system using cellular barcoding technology

Dynamic Characterization of a Full-Scale Three-Story Mass Timber Building Structure

Dynamic Characterization of a Full-Scale Three-Story Mass Timber Building Structure

Dynamic characterization of a modern heritage structure: the Palazzetto dello Sport by Pier Luigi Nervi

Dynamic characterization of a modern heritage structure: the Palazzetto dello Sport by Pier Luigi Nervi

Comparative study of experimental assessment methodologies for the dynamic characterization of elastic elements

Comparative study of experimental assessment methodologies for the dynamic characterization of elastic elements

Chemical mechanical polishing of sapphire elucidated by densely discrete phase model and verified using atomic force microscopy

The chemical mechanical polishing (CMP) is extensively applied in sapphire substrate processing. However, the mechanism is unclear because of the challenging in the dynamic characterization. In this paper, effects of the polishing speeds, slurry concentrations, and abrasive sizes on the removal action of granular flow in sapphire CMP are investigated using the discrete particle model (DPM) and densely discrete phase model (DDPM). Contours of the residence time, concentration, and abrasive velocity present that rotation speeds of the wafer and pad (30 and 80 rpm respectively) are beneficial to improving sapphire CMP performance. When the SiO2 slurry concentration is higher than 1 wt%, DDPM is more suitable for the fluid-solid flow in sapphire CMP compared to DPM. As the slurry concentration increases, the growth trend of material removal rate (MRR) slows down because of the reduction of the integral particle erosion ratio (PER). The 100 nm SiO2 abrasive can obtain the maximum MRR (10.90×10−9 nm/s), although its PER is 2 × 10−5 of 5 µm particles’ PER. The in-situ atomic force microscopy experiments prove the MRR function of granular flow owing to the hydro-dynamic contact. In addition, the removal ability will be improved by enhancing the interactive force between the abrasive and sapphire. It provides a novel idea to boost the efficiency of sapphire CMP.

Dynamic Mueller matrix polarimetry using generalized measurements

Mueller matrices provide a complete description of a medium’s response to excitation by polarized light, and their characterization is important across a broad range of applications from ellipsometry in material science to polarimetry in biochemistry, medicine and astronomy. Here we introduce single-shot Mueller matrix polarimetry based on generalized measurements performed with a Poincaré beam. We determine the Mueller matrix of a homogeneous medium with unknown optical activity by detecting its optical response to a Poincaré beam, which across its profile contains all polarization states, and analyze the resulting polarization pattern in terms of four generalized measurements, which are implemented as a path-displaced Sagnac interferometer. We illustrate the working of our Mueller matrix polarimetry on the example of tilted and rotated wave plates and find excellent agreement with predictions as well as alternative Stokes measurements. After initial calibration, the alignment of the device stays stable for up to 8 hours, promising suitability for the dynamic characterization of Mueller matrices that change in time. Unlike traditional rotating waveplate polarimetry, our method allows the acquisition of a sample’s dynamic Mueller matrix. We expect that our feasibility study could be developed into a practical and versatile tool for the real-time analysis of optical activity changes, with applications in biomedical and biochemical research and industrial monitoring.

Characterization of mixing dynamics of the transcritical bi-swirl jets

Investigation of the transcritical coaxial swirl injectors, considering their geometrical features along with the thermodynamics nonidealities, is of central importance in science and technology. Toward this aim, the mixing dynamics of transcritical bi-swirling jets has been investigated numerically. The scale-adaptive simulation method which allows formation of a turbulent spectrum is employed to close the governing equations. The Soave-Redlich-Kwong equation-of-state along with a required portion of standard database of the national institute of standards and technology are applied to the numerical framework to estimate the real-gas thermodynamic and transport properties, respectively. Results reveal that the present numerical framework accommodating a rather low-cost turbulence approach is capable of predicting the main characteristics of transcritical coaxial injectors, including central vortex core, central recirculation zone, Kelvin-Helmholtz instabilities, and vortex interaction. Analyzing oscillatory flowfield dynamics via the power-spectral-density and proper-orthogonal-decomposition techniques highlights the prominent influences of shedding, pairing, and merging of the vortices as well as the hydrodynamic Kelvin-Helmholtz instabilities on nearfield mixing dynamics. Effects of transcritical injector back-pressure on the characteristics flow features have been studied for the first time within a wide pressure range. Numerical simulations indicate that mixing quality, in terms of characteristics time- and length-scales, increases with the ambient pressure.

Effect of global shrinkage parameter of horseshoe prior in compressed sensing

This study investigates the effect of the global shrinkage parameter τ of a horseshoe prior, one of the global–local shrinkage priors, on linear regression in sparse signal processing. Statistical mechanics methods are employed to examine the accuracy of signal estimation. The phase diagram of the success and failure of signal recovery in noiseless compressed sensing with varying τ is discussed from the viewpoint of dynamic characterization of approximate message passing (AMP) as a solving algorithm and static characterization of the free-energy landscape. It is found that there exists a parameter region where the AMP algorithm can hardly recover the true signal, even though the true signal is locally stable. The analysis of the free-energy landscape also provides important insight into the optimal choice of τ.

Unveiling multi-wave patterns: dynamic characterization and sensitivity analysis of the Yu-Toda-Sasa-Fukuyama model in lattice and liquid

In this study, an examination of the Yu-Toda-Sasa-Fukuyama equation is undertaken, a model that characterizes elastic waves in a lattice or interfacial waves in a two layer liquid. Our emphasis lies in conducting a comprehensive analysis of this equation through various viewpoints, including the examination of soliton dynamics, exploration of bifurcation patterns, investigation of chaotic phenomena, and a thorough evaluation of the model’s sensitivity. Utilizing a simplified version of Hirota’s approach, multi-soliton pattens, including 1-wave, 2-wave, and 3-wave solitons, are successfully derived. The identified solutions are depicted visually via 3D, 2D, and contour plots using Mathematica software. The dynamic behavior of the discussed equation is explored through the theory of bifurcation and chaos, with phase diagrams of bifurcation observed at the fixed points of a planar system. Introducing a perturbed force to the dynamical system, periodic, quasi-periodic and chaotic patterns are identified using the RK4 method. The chaotic nature of perturbed system is discussed through Lyapunov exponent analysis. Sensitivity and multistability analysis are conducted, considering various initial conditions. The results acquired emphasize the efficacy of the methodologies used in evaluating solitons and phase plots across a broader spectrum of nonlinear models.

Measurement report: Cloud and environmental properties associated with aggregated shallow marine cumulus and cumulus congestus

Abstract. Mesoscale organization of marine convective clouds into linear or clustered states is prevalent across the tropical and subtropical oceans, and its investigation served as a guiding focus for a series of process study flights conducted as part of the Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) during summer 2020, 2021, and 2022. These select ACTIVATE flights involved a novel strategy for coordinating two aircraft, with respective remote sensing and in situ sampling payloads, to probe regions of organized shallow convection for several hours. The main purpose of this measurement report is to summarize the aircraft sampling approach, describe the characteristics and evolution of the cases, and provide an overview of the datasets that can serve as a starting point for more detailed modeling and analysis studies. Six flights are described, involving a total of 80 dropsonde profiles that capture the environment surrounding clustered shallow convection. The flights include detailed observations of the vertical structure of cloud systems, comprising up to 20 in situ sampling levels. Four cases involved deepening convection rooted in the marine boundary layer that developed vertically to 2–5 km with varying precipitation amounts, while two cases captured more complex and developed cumulus congestus systems extending above 5 km. In addition to the thermodynamic and dynamic characterization afforded by dropsonde and in situ measurements, the datasets include cloud and aerosol microphysics, trace gas concentrations, aerosol and droplet composition, and cloud and aerosol remote sensing from high-spectral-resolution lidar and polarimetry.

Experimental study of multiscale dynamic characterization of the gas-solid phase in a disturbing rotary centrifugal air classifier using pressure signal testing and analysis methods

This study investigates the complex dynamic characteristics of the flow field inside a disturbing rotary centrifugal air classifier through experimental analysis. To this end, micro-pressure sensors are employed to measure pressure signals in different spatial regions under various operating conditions. The analysis includes time-frequency characterization, complexity assessment, and multi-scale energy analysis. The time-domain fluctuation characteristics of the air classifier's pressure signal are closely tied to operating parameters, with the most intense pressure fluctuations occurring in the middle and back region of the air classifier. The loaded condition intensifies the fluctuations, with particle presence exacerbating low-frequency pressure variations and affecting the cyclone's vortex stability. Additionally, the internal installation of the screen cage structure exhibits maximum complexity and randomness in the internal flow field when Rf = 45 Hz, f = 0.4 kg/s, and β = 0°, showing higher randomness and reflecting fine-scale interactions between gas and particles. Conversely, larger scale characteristics are revealed by DET values in higher detail signal levels. Changes in operational parameters, such as perturbation frequency and feeding time, significantly affect the axial distribution of multi-scale energy in the air classifier, with a greater influence on pressure fluctuation at the macroscopic scale, indicating intensified turbulent behavior between gas and particles. This study reveals the influencing mechanisms of various operating parameters on the multiscale dynamic characteristics and complexity of the flow field inside the rotary centrifugal air classifier.

Denoising an X-ray image by exploring the power of its physical symmetry

Next-generation light source facilities offer extreme spatial and temporal resolving power, enabling multiscale, ultra-fast and dynamic characterizations. However, a trade-off between acquisition efficiency and data quality needs to be made to fully unleash the resolving potential, for which purpose powerful denoising algorithms to improve the signal-to-noise ratio of the acquired X-ray images are desirable. Yet, existing models based on machine learning mostly require massive and diverse labeled training data. Here we introduce a self-supervised pre-training algorithm with blind denoising capability by exploring the intrinsic physical symmetry of X-ray patterns without requiring high signal-to-noise ratio reference data. The algorithm is more efficient and effective than algorithms without symmetry involved, including an supervised algorithm. It allows us to recover physical information from spatially and temporally resolved data acquired in X-ray diffraction/scattering and pair distribution function experiments, where pattern symmetry is often well preserved. This study facilitates photon-hungry experiments as well as in situ experiments with dynamic loading.

High viscosity ratio multicomponent flow simulations in porous media using a pseudo-potential central moment lattice Boltzmann method

Multicomponent Immiscible flows within porous media are a pivotal concern in engineering applications, especially in contexts such as oil reservoirs, which exhibit a broad spectrum of properties, including varying viscosities. The precise characterization of flow dynamics, particularly when confronted with a dynamic contact interface within intricate and heterogeneous structures, has remained a significant challenge in the field. This study employs an enhanced Pseudo-potential Central Moment Lattice Boltzmann Method to simulate multicomponent immiscible flows within porous media. The model is implemented through an in-house CUDA code (called Dena) to leverage the parallel processing capabilities of the Lattice Boltzmann Method. In order to assess the accuracy and effectiveness of this method, several test cases are examined, including the Capillary Intrusion Test, the Fingering Process, and the Drainage Process within a real porous medium. Comparative analysis against analytical and experimental results substantiates the model's capabilities and accuracy. Furthermore, the impact of viscosity ratio variations among different flow components within porous media is investigated. With the developed approach, it is possible to span a range of viscosity ratios up to 2132. The findings underscore the model's stability and accuracy in simulating high-viscosity ratio multicomponent fluid flows within porous media.

The prevalent dynamic and genetic characterization of mcr-1 encoding multidrug resistant Escherichia coli strains recovered from poultry in Hebei, China

ObjectivesColistin is known as the last resort antibiotic to treat the infections caused by multidrug resistant foodborne pathogens. The emergence and widespread dissemination of plasmid-mediated colistin resistance gene mcr-1 in the Escherichia coli (E. coli) incurs potential threat to public health. Here, we investigated the epidemiology, transmission dynamics, and genetic characterization of mcr-1 harbouring E. coli isolates from poultry originated in Hebei Province, China. MethodsA total of 297 faecal samples were collected from the two large poultry farms in Hebei Province, China. The samples were processed for E. coli identification by matrix-assisted laser desorption ionization-time of flight mass spectrometry and 16S rDNA sequencing. Then, the mcr-1 gene harbouring E. coli strains were identified by polymerase chain reaction and subjected to antimicrobial susceptibility testing by broth microdilution assay. The genomic characterization of the isolates was done by whole genome sequencing using the various bioinformatics tools, and multi-locus sequence typing was done by sequence analysis of the seven housekeeping genes. The conjugation experiment was done to check the transferability of mcr-1 along with the plasmid stability testing. ResultsA total of six mcr-1 E. coli isolates with minimum inhibitory concentration of 4 μg/mL were identified from 297 samples (2.02%). The mcr-1 harbouring E. coli were identified as multidrug resistant and belonged to ST101 (n = 4) and ST410 (n = 2). The genetic environment of mcr-1 presented its position on IncHI2 plasmid in 4 isolates and p0111 in 2 isolates, which is a rarely reported plasmid type for mcr-1. Moreover, both type of plasmids was transferable to recipient J53, and mcr-1 was flanked by 3 mobile elements ISApl1, Tn3, and IS26 forming a novel backbone Tn3–IS26-mcr-1– pap2-ISApl1 on the p0111 plasmid. The phylogenetic analysis shared a common lineage with mcr-1 harbouring isolates from the environment, humans, and animals, which indicate its horizontal spread among the diverse sources, species, and hosts. ConclusionThis study recommends the one health approach for future surveillance across multiple sources and bacterial species to adopt relevant measures and reduce global resistance crises.

#1967 Towards the design optimisation of catheters for paediatric dialysis using a bioengineering approach

Abstract Background and Aims Central venous lines (CVLs) used for haemodialysis (HD) in children are associated with a high complication rate, leading to inadequate dialysis and need for a line replacement in nearly 45% of children on HD. This high complication rate may be due to poor CVL configurations, designed without considering specific anatomical differences between children and adults. Using a bioengineering approach, we aim to provide a fluid dynamics characterization of different CVL models commonly used in children to establish an association between CVL design and clinical complications, and to improve CVL performance by optimising their design. Method Computational fluid dynamics (CFD) using modelling and simulations is a powerful engineering tool that use computers to study complex systems, applying mathematics, physics and computer science. Four models of CVLs of varying designs and sizes (6.5Fr, 8Fr, 10Fr and 14Fr) were scanned by microCT to reconstruct computational models. CFD analyses were set up to simulate blood flow within the CVLs under both ideal and realistic models of superior vena cava. A variety of flow rates, routinely used in clinical practice, were applied to study the whole range of working conditions. Haemodynamic features that cannot be measured in vivo such as high shear stresses and large areas of stagnation, were analysed. CFD findings were compared to clinical outcomes (n = 26 patients with 57 lines) and to the blood clots distribution of CVLs removed from patients (n = 8). Fluid dynamics characteristics of the CVLs studied were used to set up a preliminary design optimisation process of a 6.5F CVL model. Using sampling methods, a variety of CVL designs were created starting from the original model and results were compared. Results In all the simulated CVLs, the arterial lumens showed the highest stagnation and recirculation areas. The role of arterial tip configuration was negligible for the blood flows and the proximal side holes played a major role for blood aspiration being also subject to the highest levels of shear stress, regardless of the design. In all the anatomical models, blood velocity increased after catheter insertion (Fig. 1a) together with wall shear stresses. CFD results were in accordance with the clinical data which showed a higher recurrence rate of thrombosis for the 8Fr and 10Fr CVLs. Also, microCT of the CVLs removed due to complications confirmed presence of thrombosis at the catheter tips. Results suggest that shear stress is the parameter most strongly related to clinical complications. The preliminary design optimisation study was used to find the parameters which have the highest influence on the CVL performance. Preliminarily optimised designs of the 6.5F model showed a better haemodynamic performance, reducing stagnation areas (Fig. 1b). Conclusion Characterisation of the fluid dynamics of commercially available CVLs explains some of the clinical outcomes experienced by patients. Identification of potential design-related complications in CVLs has allowed to set up the optimisation process which will lead to new CVL designs with improved blood flow distribution and minimal damage to blood cells. Funding Kidney Research UK, PhD fellowship and MedTech grants.

Vanadium in silicon carbide: telecom-ready spin centres with long relaxation lifetimes and hyperfine-resolved optical transitions

Vanadium in silicon carbide (SiC) is emerging as an important candidate system for quantum technology due to its optical transitions in the telecom wavelength range. However, several key characteristics of this defect family including their spin relaxation lifetime (T1), charge state dynamics, and level structure are not fully understood. In this work, we determine the T1 of an ensemble of vanadium defects, demonstrating that it can be greatly enhanced at low temperature. We observe a large spin contrast exceeding 90% and long spin-relaxation times of up to 25 s at 100 mK, and of order 1 s at 1.3 K. These measurements are complemented by a characterization of the ensemble charge state dynamics. The stable electron spin furthermore enables high-resolution characterization of the systems’ hyperfine level structure via two-photon magneto-spectroscopy. The acquired insights point towards high-performance spin-photon interfaces based on vanadium in SiC.

Mobility of sodium ions in agarose gels probed through combined single- and triple-quantum NMR

Metal ions, including biologically prevalent sodium ions, can modulate electrostatic interactions frequently involved in the stability of condensed compartments in cells. Quantitative characterization of heterogeneous ion dynamics inside biomolecular condensates demands new experimental approaches. Here we develop a 23Na NMR relaxation-based integrative approach to probe dynamics of sodium ions inside agarose gels as a model system. We exploit the electric quadrupole moment of spin-3/2 23Na nuclei and, through combination of single-quantum and triple-quantum-filtered 23Na NMR relaxation methods, disentangle the relaxation contribution of different populations of sodium ions inside gels. Three populations of sodium ions are identified: a population with bi-exponential relaxation representing ions within the slow motion regime and two populations with mono-exponential relaxation but at different rates. Our study demonstrates the dynamical heterogeneity of sodium ions inside agarose gels and presents a new experimental approach for monitoring dynamics of sodium and other spin-3/2 ions (e.g. chloride) in condensed environments.

Revisiting the Characterization of Resting Brain Dynamics with the Permutation Jensen-Shannon Distance.

Taking into account the complexity of the human brain dynamics, the appropriate characterization of any brain state is a challenge not easily met. Actually, even the discrimination of simple behavioral tasks, such as resting with eyes closed or eyes open, represents an intricate problem and many efforts have been and are being made to overcome it. In this work, the aforementioned issue is carefully addressed by performing multiscale analyses of electroencephalogram records with the permutation Jensen-Shannon distance. The influence that linear and nonlinear temporal correlations have on the discrimination is unveiled. Results obtained lead to significant conclusions that help to achieve an improved distinction between these resting brain states.