Propagation Of Different Types Research Articles

Structure and Characteristics of Synoptic-Scale Waves in the Northern Eurasian Storm Track during Summer

Abstract This study examined the dominant structure and characteristics of synoptic-scale (2–8-day periods) waves over northern Eurasia during 40 summer seasons (June–August, 1979–2018). The synoptic-scale wave patterns are isolated using an extended empirical orthogonal function (EEOF) analysis on the 300-hPa geopotential height anomalies, and a composite based on atmospheric circulation fields and gridded precipitation product. The wave patterns are classified into two types from two pairs of EEOF modes. These two different wave types are defined as the polar frontal (PF) mode and Arctic frontal (AF) mode, respectively. The PF-mode waves are initiated in the North Atlantic sector to the west of the British Isles. They propagate eastward across Siberia into the North Pacific, and produce precipitation mainly over the Eurasian polar frontal zone. The AF-mode wave train arcs along the climatological Arctic frontal zone (AFZ). The AF-mode waves originate near the Scandinavian Peninsula. Their eastward passage brings precipitation along the AFZ. The development of the synoptic-scale waves is reflected by unique background conditions over northern Eurasia. The lower-tropospheric baroclinicity in southern Siberia and central Asia favored the baroclinic growth of the PF-mode waves. The AF-mode waves are trapped in the well-organized baroclinic zone along the north coast of the Eurasian continent. The baroclinic zone is coupled with a band of large meridional gradient of potential vorticity in the upper troposphere, suggesting that this band acts as a waveguide for the AF-mode waves. Significance Statement This study examines the synoptic-scale waves in the 2–8-day range of time scales over northern Eurasia during summer. The synoptic-scale waves are categorized into two distinct types at different latitude bands by the EEOF analysis on the 300-hPa z anomalies. They are defined as polar frontal (PF) mode and Arctic frontal (AF) mode. Then the EEOF-based composite analysis is conducted to detect the large-scale circulation anomalies associated with the propagation of different types of synoptic-scale waves. The structure and characteristics are examined. The roles of the mean background conditions in the development and propagation of the respective types are discussed. The behavior of these wave disturbances as rain-producing weather systems is also examined.

Propagation of Nonlinear Dust-Acoustic Waves in a Self-Gravitating Collision Magnetized Dusty Plasma in Earth’s Magnetosphere

The nonlinear propagation of different types of DANW acoustic dust nonlinear waves has been investigated in a magnetized dusty plasma consisting of negatively charged dust particles, Maxwellian electrons, and ions. Application of the standard reductive perturbation theory is used to derive the corresponding three-dimensional nonlinear a complex Ginzburg–Landau (3D-CGLE) equation which governs the dynamics of the dust-acoustic wave packets. The stationary analytical solutions of the CGLE are numerically analysed where the effect of the physical parameters of the dusty plasma model on the wave’s propagation is taken into account. It has been found that there can be a relationship between the appearance of soliton waves and electromagnetic waves, as well as between shock-like waves and periodic travelling waves. Expression of the importance of these findings is the cornerstone of explaining the true relationship between the propagation of nonlinear waves in the physics of space, for example, the Earth’s magnetic field.

The phase spiral in Gaia DR3

Aims. We aim to study the phase spiral in the Milky Way (MW) disc with data from the third data release of Gaia (DR3) and use it as an inference tool to decipher the late-time evolution of the Galaxy. Methods. We used an edge-detection algorithm to find the border of the phase spiral, allowing us to robustly quantify its shape at different positions and for different selections. We calculated the time of onset of the phase-mixing by determining the different turns of the phase spiral and using the vertical frequencies from commonly used models of the gravitational potential of the MW. Results. We find that the phase spiral extends down to −1.2 kpc in height below the plane (about 3–5 scale heights of the thin disc) and beyond ±50 km s−1 in VZ. We see a secondary branch mostly at positive vertical velocities when coloured by azimuthal velocity and in the counts projection. We also find complex variations of the phase spirals with angular momentum and azimuth. All these findings are possible evidence of multiple perturbations (from different times or from different perturbers) and/or of the complexity of the phase-mixing process. We detect the phase spiral from 6 to 11 kpc from the Galactic centre and find signatures of vertical asymmetries 1–2 kpc beyond this range. We measure small but clear variations with azimuth. When we determine the phase mixing times from the phase spiral at different angular momenta and using the different spiral turns (at different Z), we obtain inconsistent times with systematic differences (times increasing with |LZ| and with |Z|). Our determinations are mostly in the range of [0.3–0.9] Gyr, with an average of 0.5 Gyr. The inconsistencies do not change when using different commonly used potential models for the MW, different stellar distances, or frequencies for different kinetic temperatures; they could stem from the inconsistency of the assumed gravitational potentials with the true MW, and from oversimplification of the modelling, in particular where self-gravity is neglected or where multiple perturbations and/or interference with other processes are not considered. Conclusions. The wealth of information provided by the new Gaia DR3 data should encourage us to make progress in crucial modelling aspects of the disc dynamics, such as non-equilibrium, self-gravity, propagation of different types of bending waves, and interactions between different mechanisms. Such advancements could finally enable us to establish the origin of the phase spiral and its relation to the Sagittarius dwarf galaxy.

VERIFICATION OF THE WAVE FACTORIZATION METHOD FOR CALCULATION OF DISTRIBUTED SYSTEMS DURING TOWING IN A FLOW IN ACCELERATION MODE

For purposes of asymmetric confrontation with the Russian Navy, distributed systems (DS; cable, tethered, etc.) for unmanned underwater vehicles need further development and improvement. To date, specifics and methods of designing such DSs are insufficiently covered in scientific and technical literature. Distributed systems include towed systems of constant or variable length in a flow of liquid, underwater communication cables, pillars of offshore oil platforms, etc. This definition includes mechanical objects with one of the linear dimensions at least 10 – 20 times larger than the other two. The main limitations for application of the finite difference method (FDM) for numerical modeling of wave propagation and reflection in DS are the peculiarities of the defining quasi-linear equations. They are related to the need of simultaneous calculation of variables responsible for fast and slow wave processes. The term "singularly perturbed system of equations" is used for such systems of equations. These perturbations are the result of a significant difference in propagation velocities of longitudinal, configurational, bending, and torsional waves in DS at the physical level, etc. In this regard, it is necessary to apply the special step-by-step methods of regularization and filtering of numerical results. This imposes certain limitations on the possibility of simulating real processes and on the accuracy of obtained results, and forces the use of the implicit difference schemes and high-frequency filtering. The method of parallelization of the finite-difference operator and the program code according to the wave type is considered. The idea of parallelization by waves is based on the physical feature of propagation of different types of waves in distributed systems – a difference of 10 – 100 or more times between the propagation velocities of the longitudinal, transverse (configurational), bending and torsional waves in DS. The increase in productivity of the MPI version of a programming code when performing calculations on the SMP system is on average at least 30 – 100%, depending on the required accuracy of calculations and parallelization options. The version of the parallelized code, which uses the wave factorization method, is relevant when solving tasks of DS control, operational numerical analysis of transient modes of motion, etc., where performance is critically necessary. The comparative assessment of the accuracy of the experimental data, the original (non-parallelized) algorithm and the parallelized algorithm was carried out using the example of the numerical solution of the problem of the towing vessel’s movement in the acceleration mode when towing the DS.

Real-time in-depth damage identification and health index system for carbon fiber-reinforced composites using electromechanical behavior and data processing tools

Structural health monitoring using electromechanical behavior can help detect various damage types and failure modes in composites. However, only the presence of damage and structural failure can be monitored. For a thorough identification of damage in composites, this paper proposes an electromechanical data analysis and processing methodology using principal component analysis and k-means clustering. The health state of unidirectional carbon fiber-reinforced plastic (CFRP) composites was monitored using self-sensing data. Various types of damage and failure modes in carbon fibers with different directionality were investigated based on in-depth damage analysis using a machine-learning-based data processing technique. A novel health index system for damage propagation investigation was proposed based on an electromechanical behavior analysis. The results produced by the damage index system were compared with those obtained by ABAQUS simulation and mechanical behavior analysis to determine the rationality of the system. An advanced condition-based monitoring methodology can help investigate the current health state of composites and the propagation of different types of damage. The proposed system has potential applications, and our results provide guidelines for self-sensing research.

A 3-D micromechanical framework to study damage propagation and failure of printed aligned discontinuous fiber-reinforced composites

This paper presents a novel and efficient micromechanical framework for finite element simulation of damage and failure in 3-D printed aligned discontinuous fiber-reinforced composites. The framework can predict the initiation and propagation of different types of damage in the composite under tensile loading along the fibers’ axis. The micromechanical framework includes the microstructural representation of the composite with explicit fibers and matrix in addition to linear expansions at the ends. Accurate constitutive equations are utilized for fibers, matrix, and fiber/matrix interfaces in the microstructural representation. Fibers’ locations and lengths are generated randomly; based on a target distribution for the fibers’ aspect ratios measured experimentally; within the microstructural representation. Optimal microstructural representative dimensions for reliable investigation of the mechanical response are computed by conducting sensitivity analyses. The accuracy of the micromechanical framework is validated versus the experimental results of a 3-D printed aligned discontinuous fiber-reinforced composite as the composite of interest. It is shown that the proposed framework can simulate various aspects of the mechanical response, including the failure pattern and stress-strain behavior. Subsequently, the sensitivity of the mechanical response of the composite to a few constitutive equation-related parameters, including the strength and fracture toughness of the fiber/matrix interfaces and the matrix strength, is investigated. The correlation between the studied parameters and the composite’s strength and failure pattern is also analyzed and discussed. This paper delivers valuable guidance on the mechanical response of printed aligned discontinuous fiber-reinforced composites, eventually resulting in the paradigm-shifting design, manufacturing, and analysis of such advanced composites.

Flame speed in diffusion dominated premixed flames

Development of a premixed flame theory that includes the effects of flame stretch and curvature has been at the forefront of combustion research. Diffusion dominated flames such as highly curved flame balls present a challenging flame structure that has not been included in current flame stretch theory so far. In such flames, the relationship between consumption speed and negative displacement speed usually marks the boundary of what flame stretch theory can predict. In this work, our objective is to derive a general formulation which naturally includes this relationship. We use flamelet equations derived using a mass based stretch rate and show that if the diffusion flux at the unburnt side is not ignored, as is normally done in flame stretch theory, a formulation that can describe the propagation of different types of premixed flames can be derived. Based on the thin reaction zone assumption, solutions from theory are verified against numerical results for 1D ideal flame balls. Further verification is done for multi-dimensional ball-like flames, where both convection and diffusion dominated regions are present for highly curved flames. It is shown that the extended theory is able to predict the flame kinematics in a better way by describing the diffusion dominated flame propagation as well.

Numerical Simulation of Singularity Propagation Modeled by Linear Convection Equations with Spatially Heterogeneous Nonlocal Interactions

We study the propagation of singularities in solutions of linear convection equations with spatially heterogeneous nonlocal interactions. A spatially varying nonlocal horizon parameter is adopted in the model, which measures the range of nonlocal interactions. Via heterogeneous localization, this can lead to the seamless coupling of the local and nonlocal models. We are interested in understanding the impact on singularity propagation due to the heterogeneities of the nonlocal horizon and the local and nonlocal transition. We first analytically derive equations to characterize the propagation of different types of singularities for various forms of nonlocal horizon parameters in the nonlocal regime. We then use asymptotically compatible schemes to discretize the equations and carry out numerical simulations to illustrate the propagation patterns in different scenarios.

Statistical Characteristics and Long-Term Variations of Major Sudden Stratospheric Warming Events

Using NCEP/NCAR reanalysis data, we investigate the statistical characteristics and the long-term variations of major sudden stratospheric warming (SSW) events in the Northern Hemisphere. We find that the strength and duration of major SSW events has increased from 1958 to 2019 and that this is due to the strengthening of the winter planetary wave activity. We find that the frequency of displacement and split SSW events differs between early, middle and late winter. Early and middle winter are dominated by displacement and split SSW events, respectively, but the frequency of the two types of event is almost equal in late winter. This is due to the differences in the relative strength of wavenumber-1 and wavenumnber-2 planetary wave activity in the three winter periods. As a result of the increase in upward planetary wave activity and the decrease in westerly winds around the polar vortex in middle winter, a shift in the timing of SSW events toward middle winter is detected. In addition, we revealed the influence of the downward propagation of different types of SSW event on the surface temperature anomaly. There were surface cold centers in Russia and northern China after the middle split SSW events; by contrast, there were more cold events in North America after the middle split SSW events.

Endometriosis a brief review: evaluation of crucial risk factors and current treatment regimes

Endometriosis is an estrogen-dependent chronic inflammatory disease associated with substantial morbidity, including dyspareunia, dysmenorrhea, pelvic pain, multiple surgery, and infertility. This disease has a high impact on both woman’s physical and mental wellbeing. The etiology of endometriosis is complex and multifactorial. The risk factors associated with the development of endometriosis include family history, menstrual and reproductive cycle, low body mass index (BMI), diet, alcohol uses, smoking, environmental factors, immune system, genetic factors and intrinsic abnormalities in the endometrium. There exist many theories on the initiation and propagation of different types of endometriotic lesions and consequent biological disturbances, of which the most common is the Sampson’s theory according to which the retrograde flow of menstrual blood is linked to the development of endometriosis. Endometriosis affected women have a higher risk than the general female population, for ovarian cancer, coronary heart disease (CHD), and other long-term disease risks as well for autoimmune and atopic disorders. Therefore it becomes a necessity for the clinician not only to attain right diagnosis but also follow up for the other associated disorders. In this review, we have considered the crucial risk factors and biomarkers of the endometriosis as well as the possible pathogenesis towards the development of endometriosis and its prevention strategies. The currently available therapies for the control and treatment of endometriosis have also been elaborated.

Capital Flows in the Euro Area and TARGET2 balances

We estimate a panel VAR model for the euro area to quantitatively assess how the uneven recourse of national banking systems in the euro area to the ECB's unconventional refinancing operations that led to the accumulation of large TARGET2 balances, has contributed to the propagation of different types of structural economic shocks as well as to the historical evolution of aggregate economic activity in euro area member countries in the period 2008-2014. Our results suggest that the built-up of TARGET2 balances was mainly driven by capital flow shocks while being barely responsive to other aggregate shocks. Furthermore, on basis of counterfactual experiments we find that the ability to build-up sizable TARGET2 liabilities has contributed substantially to avoid deeper recessions in the distressed euro area member countries like Spain, Italy, Ireland and Portugal, while to a smaller extent depressing aggregate economic activity in core member states, such as Germany, the Netherlands and Finland.

Capital Flows in the Euro Area and TARGET2 Balances

We estimate a panel VAR model for the euro area to quantitatively assess how the uneven recourse of national banking systems in the euro area to the ECB's unconventional refinancing operations that led to the accumulation of large TARGET2 balances, has contributed to the propagation of different types of structural economic shocks as well as to the historical evolution of aggregate economic activity in euro area member countries in the period 2008-2014. Our results suggest that the built-up of TARGET2 balances was mainly driven by capital flow shocks while being barely responsive to other aggregate shocks. Furthermore, on basis of counterfactual experiments we find that the ability to build-up sizable TARGET2 liabilities has contributed substantially to avoid deeper recessions in the distressed euro area member countries like Spain, Italy, Ireland and Portugal, while to a smaller extent depressing aggregate economic activity in core member states, such as Germany, the Netherlands and Finland.

Characterizing information propagation patterns in emergencies: A case study with Yiliang Earthquake

Social media has been playing an increasingly important role in information publishing and event monitoring in emergencies like natural disasters. The propagation of different types of information on social media is critical in understanding the reaction and mobility of social media users during natural disasters. In this research, we analyzed the dynamic social networks formed by the reposting (retweeting) behaviors in Weibo.com (the major microblog service in China) during Yiliang Earthquake. We developed a Multinomial Naïve Bayes Classifier to categorize the microblog posts into five types based on the content, and then characterized the information propagation patterns of the five types of information at different stages after the earthquake occurred. We found that the type of information has significant influence on the propagation patterns in terms of scale and topological features. This research revealed the important role of information type in the publicity and propagation of disaster-related information, thus generated data-driven insights for timely and efficient emergency management using the publicly available social media data.

Effect of defects, magnetocrystalline anisotropy, and shape anisotropy on magnetic structure of iron thin films by magnetic force microscopy

Microstructures of magnetic materials, including defects and crystallographic orientations, are known to strongly influence magnetic domain structures. Measurement techniques such as magnetic force microscopy (MFM) thus allow study of correlations between microstructural and magnetic properties. The present work probes effects of anisotropy and artificial defects on the evolution of domain structure with applied field. Single crystal iron thin films on MgO substrates were milled by Focused Ion Beam (FIB) to create different magnetically isolated squares and rectangles in [110] crystallographic orientations, having their easy axis 45° from the sample edge. To investigate domain wall response on encountering non-magnetic defects, a 150 nm diameter hole was created in the center of some samples. By simultaneously varying crystal orientation and shape, both magnetocrystalline anisotropy and shape anisotropy, as well as their interaction, could be studied. Shape anisotropy was found to be important primarily for the longer edge of rectangular samples, which exaggerated the FIB edge effects and provided nucleation sites for spike domains in non-easy axis oriented samples. Center holes acted as pinning sites for domain walls until large applied magnetic fields. The present studies are aimed at deepening the understanding of the propagation of different types of domain walls in the presence of defects and different crystal orientations.

Numerical simulation of rolling contact fatigue crack growth in rails with the rail bending and the frictional contact

Due to the repeated passages of the wheels, the rail is subjected to time-dependent, multiaxial, non-proportional, mixed mode cyclic loading. Under these conditions of loading, the fatigue cracks can appear in the surface or subsurface of the rails. This paper attempts to investigate the multiaxial fatigue crack growth in rails using 3D numerical simulations taking into account the frictional contact between crack faces and the rail bending. Firstly, a quick description is given of the two-scale strategy (global structure and local interface) for the cracked body problem with frictional contact between the crack faces. In this strategy, a stabilized three-field weak formulation is proposed to avoid possible oscillations in the local solution linked to the LBB condition. This formulation is discretized within the framework of the eXtended Finite Element Method (XFEM). Then, the LATIN non-linear solver is used to solve the two-scale problem. Secondly, we focus on the 3D railway track model with an initial crack on the rail surface. The sleepers and the rail fastenings are modelled by introducing constraints on the vertical displacement of some nodes on the rail foot. This 3D cracked rail model is used to simulate the propagation of different types of crack (in curve, in straight line) under the multiaxial wheel-rail contact loading. Finally, a parametric study is investigated in order to clarify the influence of the friction coefficient between crack faces, the position of the crack in relation to the sleepers and the stiffness of the track on the crack growth behavior.

Transport of correlations in a harmonic chain

We study the propagation of different types of correlations through a quantum bus formed by a chain of coupled harmonic oscillators. This includes steering, entanglement, mutual information, quantum discord, and Bell-like nonlocality. The whole system consists of the quantum bus (propagation medium) and other quantum harmonic oscillators (sources and receivers of quantum correlations) weakly coupled to the chain. We are particularly interested in using the point of view of transport to spot distinctive features displayed by different kinds of correlations. We found, for instance, that there are fundamental differences in the way steering and discord propagate, depending on the way they are defined with respect to the parties involved in the initial correlated state. We analyzed both the closed- and open-system dynamics as well as the role played by thermal excitations in the propagation of the correlations.

Chiral asymmetry in propagation of soliton defects in crystalline backgrounds

By applying Darboux-Crum transformations to a Lax pair formulation of the Korteweg-de Vries (KdV) equation, we construct new sets of multi-soliton solutions to it as well as to the modified Korteweg-de Vries (mKdV) equation. The obtained solutions exhibit a chiral asymmetry in propagation of different types of defects in crystalline backgrounds. We show that the KdV solitons of pulse and compression modulation types, which support bound states in semi-infinite and finite forbidden bands in the spectrum of the perturbed quantum one-gap Lame system, propagate in opposite directions with respect to the asymptotically periodic background. A similar but more complicated picture also appears for the multi-kink-antikink mKdV solitons that propagate with a privileged direction over topologically trivial or topologically nontrivial crystalline background in dependence on position of energy levels of the trapped bound states in the spectral gaps of the associated Dirac system. An exotic N=4 nonlinear supersymmetric structure incorporating Lax-Novikov integrals of a pair of perturbed Lame systems is shown to underlie the Miura-Darboux-Crum construction. It unifies the KdV and mKdV solutions, detects the defects and distinguishes their types, and identifies the types of crystalline backgrounds.

Propagation of Different Types of Inflow Distortions through a Contra Rotating Fan Stage

AbstractThis paper aims to explain the propagation of different types of inflow distortions through a contra rotating fan stage. Inflow distortions like circumferential, radial and complex distortions were artificially generated using meshes of different porosities. The overall effects of these distortions are determined in the terms of the fan performance map. It is attempted to explain the propagation of inflow distortion using distortion descriptors like circumferential intensity, circumferential extent and radial intensity at the design mass flow rate. These are described for different speed combinations of both the rotors at the inlet, the exit of rotor-1 and at the exit of rotor-2. It is important to observe here that even for purely circumferential inflow distortion, the distortion does not remain purely circumferential, rather it propagates both circumferentially and radially along the stage. For the hub-strong complex inflow distortion, the higher magnitude of circumferential intensity and circumferential extent at the exit of rotor-1 clearly indicates the strong distortion effect that leads to poor performance of the stage amongst all distortion configurations studied. With radial inflow distortion, the radial redistribution of the flow at the exit of rotor-1 plays an important role in the performance of the rotor-2 and thereby for the stage.

The Robustness and Mutual Information Entropy of Random Modular Boolean Networks

Random Boolean networks have been proposed as a basic model of genetic regulatory networks for more than four decades. Attractors have been considered as the best way to represent the long-term behaviors of random Boolean networks. Most studies on attractors are made with random topologies. However, the real regulatory networks have been found to be modular or more complex topologies. In this work, we extend classical robustness and entropy analysis of random Boolean networks to random modular Boolean networks. We firstly focus on the robustness of the attractor to perturbations with different parameters. Then, we investigate and calculate how the amount of information propagated between the nodes when on an attractor, as quantified by the average pairwise mutual information. The results can be used to study the capability of genetic information propagation of different types of genetic regulatory networks.

Theories on the pathogenesis of endometriosis.

Endometriosis is a common, chronic inflammatory disease defined by the presence of extrauterine endometrial tissue. The aetiology of endometriosis is complex and multifactorial, where several not fully confirmed theories describe its pathogenesis. This review examines existing theories on the initiation and propagation of different types of endometriotic lesions, as well as critically appraises the myriad of biologically relevant evidence that support or oppose each of the proposed theories. The current literature suggests that stem cells, dysfunctional immune response, genetic predisposition, and aberrant peritoneal environment may all be involved in the establishment and propagation of endometriotic lesions. An orchestrated scientific and clinical effort is needed to consider all factors involved in the pathogenesis of this multifaceted disease and to propose novel therapeutic targets to reach effective treatments for this distressing condition.