Streaming Velocity Research Articles

Leveraging big data analytics in 5G‐enabled IoT and industrial IoT for the development of sustainable smart cities

AbstractThere has been an exponential growth in the number of low‐cost heterogeneous sensor devices that are connected to the internet in the existing infrastructure of smart cities in the past decade. These sensors and actuator devices are employed in various industries to collect invaluable data that greatly impacts business decisions. State‐of‐the‐art research is being carried out to process the high‐volume data collected in high velocity streams with high variability in order to draw meaningful insights to cater to business needs in various domains. Big data analytics finds diversified opportunities in 5G‐enabled Internet of Things (IoT) and industrial IoT environment to study the data patterns and produce new results which provides big organizations a conducive environment to take informed decisions. This article presents an exhaustive investigation of the various applications and algorithms of the big data analytics in 5G‐driven IoT and industrial IoT systems with a detailed taxonomy of the existing analytical systems and also the challenges specific to the applications in an IoT environment. A holistic understanding on the importance of security and privacy of big data during the development of smart city infrastructure in high velocity streaming process has been explained for a broad understanding of the big data streaming processes. A thorough analysis of important data mining algorithms such as classification, association rule mining, clustering, and prediction methods for big IoT data from the recent literature also has been presented to provide a clear understanding of existing issues in handling big data in 5G‐enabled IoT for the development of sustainable smart city infrastructure.

Surface waves in a streaming plasma propagating in a duct: kinetic theory

The dispersion relation of a surface wave generated by a drifting plasma in an infinite duct surrounded by vacuum is derived non-relativistically by means of the Vlasov equation. The kinematic boundary condition imposed on the distribution function, the specular reflection conditions on the four sides of duct, can be satisfied by placing an infinite number of fictitious surface charge sheets spaced by the duct widths. The surface wave mode is specifically the transverse magnetic mode, often called the surface polariton, which propagates with phasor $\exp ({{\rm i}k_zz-{\rm i}\omega t})$ . The method of placing appropriate fictitious surface charge sheets enables one to treat the surface waves in semi-infinite, slab and duct plasmas simultaneously on an equal footing, kinetically. The streaming effect manifests itself through the Doppler-shifted frequency and a correction-like term ${u^2}/{c^2}$ , where u is the streaming velocity and c is the speed of light.

Numerical simulation on acoustic streaming characteristics in boiler tube array

Strong sound can produce acoustic streaming around the tube, which can change the flow state around the tube, and then affect the heat exchange between the tube and the surrounding medium. In order to obtain the influence law of sound wave on the heat transfer characteristics in the tube array, firstly, we study the acoustic streaming and heat transfer characteristics around a single cylindrical tube by the scheme of theoretical derivation and simulation. On this basis, we study the acoustic streaming and heat transfer characteristics in the periodic tube array. The results show that the acoustic streaming structure outside the tube is axially symmetric, and the flow direction of the inner vortices and the outer vortices are opposite. When the frequency is constant, sound pressure level (SPL) only changes the acoustic streaming velocity, not the acoustic streaming distribution. As the frequency continues to increase, the velocity peak gradually shifts from the inner vortex to the outer vortex, so the outer vortex velocity gradually becomes the main body of flow. Low frequency and high intensity sound waves can form strong acoustic streaming movement and enhance heat transfer outside the tube. In the tube array, the acoustic streaming distribution should consider the effect of different incident directions on crystal plane spacing. For incident angle φ = 0°∼34°, the ratio of maximum velocity of outer vortex to the one of inner vortex an Nusselt number (Nu) are increasing with φ increasing. In this stage, the heat transfer effect changes greatly with the change of angle. For incident angle φ = 35°∼45°, the inner and outer vortex flow velocity and Nu increases together, but the scale of outer vortex decreases. In this stage, with the change of angle, the heat transfer effect changes less due to the reduction of the scale of outer vortex dominating heat transfer between tubes. In tube arrays, the optimal flow field incidence angle is φ = 34 °and the optimal heat transfer incidence angle is φ = 45°. The sound band gap and sound pressure level enhancement exist in the tube array, which affects the acoustic streaming distribution. The results are helpful to reveal the mechanism of acoustic streaming more clearly and provide a basis for the augmentation of heat transfer in tube arrays by acoustic waves.

Tracing stars in Milky Way satellites with a-sloth

ABSTRACT We study the stellar mass-to-halo mass (SMHM) relation at z = 0 in 30 Milky Way (MW)-like systems down to the ultrafaint ($M_{\rm *}\lt 10^5\, {\rm M}_\odot$) regime using the semi-analytic model a-sloth. A new model allows us to follow star formation (SF) and the stochastic stellar feedback from individually sampled Pop II stars. Our fiducial model produces consistent results with the SMHM relation derived from abundance matching and the observed cumulative stellar mass function above the observational completeness. We find a plateau in the SMHM relation in the ultrafaint regime. The stellar mass of this plateau tells us how many stars formed before supernovae occur and regulate further SF, which is determined by the Pop II SF efficiency. We also find that the number of luminous satellites increases rapidly as M* decreases until $M_{\rm *}\approx 10^4\, {\rm M}_\odot$. Finally, we find that the relative streaming velocity between baryons and dark matter at a high redshift is important in determining the number of ultrafaint dwarf galaxies at z = 0. The new model in a-sloth provides a framework to study the stellar properties and the formation history of metal-poor stars in MW and its satellites.

Acoustic streaming in the cochlea

This presentation examines the fluid motion resulting from airborne and bone conduction excitation in the cochlea. The time-averaged velocity, termed acoustic streaming, driven by the gradient of the Reynolds stress, is of particular interest. The effect of asymmetry in the oval and the round window velocity and its influence pressure gradient across the cochlear partition and acoustic streaming is explored. It is shown that the streaming flow is a function of the reciprocal of the Strouhal, 1/S and the oscillatory Reynolds number, 1/R, have a magnitude much less than one for frequencies of interest. The work presented will focus on the parameter range R/S2 = O(1). The streaming velocity is obtained in terms of asymptotic expansion in terms of the reciprocal of the Strouhal number. Solution of the streaming flow outside the viscous region is obtained using boundary conditions derived from a matched asymptotic analysis.

Streaming velocity effects on the post-reionization 21-cm baryon acoustic oscillation signal

ABSTRACTThe relative velocity between baryons and dark matter in the early Universe can suppress the formation of small-scale baryonic structure and leave an imprint on the baryon acoustic oscillation (BAO) scale at low redshifts after reionization. This ‘streaming velocity’ affects the post-reionization gas distribution by directly reducing the abundance of pre-existing mini-haloes ($\lesssim 10^7 {\rm M}_{\bigodot }$) that could be destroyed by reionization and indirectly modulating reionization history via photoionization within these mini-haloes. In this work, we investigate the effect of streaming velocity on the BAO feature in H i 21 cm intensity mapping after reionization, with a focus on redshifts 3.5 ≲ z ≲ 5.5. We build a spatially modulated halo model that includes the dependence of the filtering mass on the local reionization redshift and thermal history of the intergalactic gas. In our fiducial model, we find isotropic streaming velocity bias coefficients bv ranging from −0.0043 at z = 3.5 to −0.0273 at z = 5.5, which indicates that the BAO scale is stretched (i.e. the peaks shift to lower k). In particular, streaming velocity shifts the transverse BAO scale between 0.121 per cent (z = 3.5) and 0.35 per cent (z = 5.5) and shifts the radial BAO scale between 0.167 per cent (z = 3.5) and 0.505 per cent (z = 5.5). These shifts exceed the projected error bars from the more ambitious proposed hemispherical-scale surveys in H i (0.13 per cent at 1σ per Δz = 0.5 bin).

Discovery of ultrafast myosin, its amino acid sequence, and structural features

Cytoplasmic streaming with extremely high velocity (∼70 μm s-1) occurs in cells of the characean algae (Chara). Because cytoplasmic streaming is caused by myosin XI, it has been suggested that a myosin XI with a velocity of 70 μm s-1, the fastest myosin measured so far, exists in Chara cells. However, the velocity of the previously cloned Chara corallina myosin XI (CcXI) was about 20 μm s-1, one-third of the cytoplasmic streaming velocity in Chara Recently, the genome sequence of Chara braunii has been published, revealing that this alga has four myosin XI genes. We cloned these four myosin XI (CbXI-1, 2, 3, and 4) and measured their velocities. While the velocities of CbXI-3 and CbXI-4 motor domains (MDs) were similar to that of CcXI MD, the velocities of CbXI-1 and CbXI-2 MDs were 3.2 times and 2.8 times faster than that of CcXI MD, respectively. The velocity of chimeric CbXI-1, a functional, full-length CbXI-1 construct, was 60 μm s-1 These results suggest that CbXI-1 and CbXI-2 would be the main contributors to cytoplasmic streaming in Chara cells and show that these myosins are ultrafast myosins with a velocity 10 times faster than fast skeletal muscle myosins in animals. We also report an atomic structure (2.8-Å resolution) of myosin XI using X-ray crystallography. Based on this crystal structure and the recently published cryo-electron microscopystructure of acto-myosin XI at low resolution (4.3-Å), it appears that the actin-binding region contributes to the fast movement of Chara myosin XI. Mutation experiments of actin-binding surface loops support this hypothesis.

Focusing of Micrometer-Sized Metal Particles Enabled by Reduced Acoustic Streaming via Acoustic Forces in a Round Glass Capillary

Two-dimensional (2D) metal-particle focusing is an essential task for various fabrication processes. While acoustofluidic devices can manipulate particles in two-dimensions, the production of these devices often demands a cleanroom environment. Therefore, acoustically excited glass capillaries present a cheap alternative to labor-intensive cleanroom production. Here, we present 2D metal microparticle focusing in a round glass capillary using bulk acoustic waves. Excitation of the piezoelectric transducer at specific frequencies leads to mode shapes in the round capillary, concentrating particles toward the capillary center. We experimentally investigate the particle line width for different particle materials and concentrations. We demonstrate the focus of copper particles approximately $1\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ in diameter down to a line of width $60.8\ifmmode\pm\else\textpm\fi{}7.0\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ and height $45.2\ifmmode\pm\else\textpm\fi{}9.3\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$, corresponding to a local concentration of 4.5% v/v, which is $90$ times higher than the concentration of the initial solution. Further, we achieve the focusing of 1-$\ensuremath{\mu}\mathrm{m}$ polystyrene particles, which is usually prevented due to acoustic streaming. Through numerical analysis, we reveal the mechanism enabling the manipulation of particles in the low-micrometer range. Due to a transition of the acoustic streaming patterns from two dominant vortices in the lower half to two dominant vortices in the upper half, the streaming velocity exhibits a local minimum while the overall acoustic energy density stays at a sufficiently high level for particle focusing, leading to a lower critical particle radius than in conventional rectangular microchannels. Finally, we use our method to eject copper particles through a tapered round capillary with an opening of $25\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ in diameter, which would not be possible without particle focusing. Our setup can be utilized for various applications that otherwise might suffer from abrasion, clogging, and limited resolution.

The role of channel height and actuation method on particle manipulation in surface acoustic wave (SAW)-driven microfluidic devices

Surface acoustic wave (SAW) micromanipulation offers modularity, easy integration into microfluidic devices and a high degree of flexibility. A major challenge for acoustic manipulation, however, is the existence of a lower limit on the minimum particle size that can be manipulated. As particle size reduces, the drag force resulting from acoustic streaming dominates over acoustic radiation forces; reducing this threshold is key to manipulating smaller specimens. To address this, we investigate a novel excitation configuration based on diffractive-acoustic SAW (DASAW) actuation and demonstrate a reduction in the critical minimum particle size which can be manipulated. DASAW exploits the inherent diffractive effects arising from a limited transducer area in a microchannel, requiring only a travelling SAW (TSAW) to generate time-averaged pressure gradients. We show that these acoustic fields focus particles at the channel walls, and further compare this excitation mode with more typical standing SAW (SSAW) actuation. Compared to SSAW, DASAW reduces acoustic streaming effects whilst generating a comparable pressure field. The result of these factors is a critical particle size with DASAW (1 upmum) that is significantly smaller than that for SSAW actuation (1.85 upmum), for polystyrene particles and a given lambda _{text {SAW}} = 200 upmum. We further find that streaming magnitude can be tuned in a DASAW system by changing the channel height, noting optimum channel heights for particle collection as a function of the fluid wavelength at which streaming velocities are minimised in both DASAW and SSAW devices.

Экспериментальное изучение акустических течений, генерируемых ультразвуковым излучением

The paper is devoted to an experimental study of the acoustic streaming generated by an ultrasonic (US) irradiation in a confined fluid volume. The container is a parallelepiped, partially filled with liquid (water), into which a piezoelectric US emitter is submerged from the top. To transmit the oscillations into the fluid, a waveguide is used whose thickness is considerably smaller than the US wavelength. The structure and velocity of the acoustic streaming, which forms in the bulk, are studied by methods of particle image velocimetry and photography. The observations are carried out in the vertical cross section, which contains the beam axis, with the use of a light sheet created by means of a continuous green laser. The illumination produces the heating in the plane of the light sheet and leads to the onset of free convection. The latter is studied: the flow structure and velocity and the time of their settling are considered at different power of illumination. The information on the natural convection properties is used during the analysis of the structure of acoustic streaming. In general, in the considered region of interest, the thermal convection does not have a substantial influence on the outcomes of the present study, but it determines the minimal velocity, which is limiting the possibility of investigation of slow flows. The observed acoustic streaming may be conventionally divided into two kinds. The first is localized near the waveguide surface and is steady-state. It possesses a regular structure and its characteristic velocity is not high. The streaming of the second kind occupies the entire fluid bulk and transforms continuously. Its velocity magnitude is higher by an order than that of first-kind streaming. An interesting peculiarity of the non-stationary acoustic streaming is that its sources may be located on the container boundaries and not only on the waveguide. This finding points to an important contribution of the reflected US waves in the fluid motion at the sufficient intensity of the US irradiation. The obtained results are going to be used during the investigation of the emulsions behavior in US fields.

Effect of microchannel protrusion on the bulk acoustic wave-induced acoustofluidics: numerical investigation.

Acoustofluidics inside the microchannel has already found its wide applications recently. Acoustic streaming and radiation force are two underlying mechanisms that determine the trajectory of microparticles and cells in the manipulation. Critical particle size of viscous effects is found to be about 1.6µm in the conventional rectangular microchannel (W × H = 380m × 160m) at the frequency of 2MHz, below which the acoustic streaming dominants, and is independent of the driving voltage. In order to effectively adjust such a critical size, a approach is proposed and evaluated numerically to enhance the acoustic streaming by adding some protrusions (i.e., in the shape of a wedge, rod, half-ellipse) to the middle of the top or bottom wall. It is found that the resonant frequency and acoustic pressure will decrease and the acoustic streaming velocity will increase significantly, respectively, with the increase of protrusion height (up to 30µm while keeping the width the same as 8µm). Subsequently, trajectory motion patterns of microparticles have apparent changes in comparison to those inside the rectangular microchannel, and acoustic streaming can even dominate the motion of large microparticles (i.e., 10µm). As a result, the critical particle size could be increased up to 72.5µm. Furthermore, different protrusion shapes (i.e., wedge, rod, half-ellipse) on the top wall were compared. The sharpness of protrusion at its tip seems to determine the acoustic streaming velocity. The wedge attached to the bottom wall had higher resonant frequency and lower acoustic streaming velocity compared with the top wedge in the same dimension. The patterns of acoustic streaming and microparticle trajectory motion in the microchannel with dual wedges on the top and bottom walls are not the superposition of those of the top and bottom wedge individually. In summary, the geometry of the microchannel has a significant effect on the induced acoustofluidics by the bulk acoustic waves. A much larger acoustic streaming velocity is produced at the tip of the protrusion to change the critical size of microparticles between acoustic streaming and radiation force. It suggests that more applications of acoustofluidics (i.e., mixing and sonoporation) to microparticles and cells in various sizes are feasible by designing an appropriate geometry of the microchannel.

Coupling mechanism of kinetic and thermal impacts of Rayleigh surface acoustic waves on the microdroplet

An experimental study has been conducted to investigate the coupling mechanism between thermal and kinetic impacts of surface acoustic waves (SAW) using a water droplet (25 µl) on the zinc oxide (ZnO) thin-film piezoelectric substrate fabricated on an aluminium plate. The temperature is measured by an infrared (IR) thermal camera, and fluid streaming was detected by particles image velocimetry (PIV). The input power ranges from 0.096 W to 3.2 W resulting in a temperature rise and streaming velocity in the droplet up to 55 °C and 24.6 mm/s, respectively. It is found that the thermal impact is insignificant at lower input power (<0.50 W); however, this becomes dominant when the input power is>2.0 W. The study also found that heat inside the droplet is distributed via streaming from the heat source. The heat is distributed from the heat source where SAW power penetrates to the droplet. Another key finding of this investigation revealed that when the input power is>0.50 W, inverse heat transfer from the droplet to the substrate is observed due to the increase in fluid temperatures.

Nonlinear dynamics of a solid particle in an acoustically excited viscoelastic fluid. I. Acoustic streaming.

An analytical theory is developed for acoustic streaming induced by an axisymmetric acoustic wave field around an isotropic solid spherical particle in a compressible viscoelastic fluid. The particle is assumed to undergo pulsation, translation, and shape deformations of all orders. The fluid motion is described by the compressible Oldroyd-B model. No restrictions are imposed on the particle size with respect to the acoustic wavelength and the viscous penetration depth. The obtained analytical solutions are used in numerical simulations. It is shown that in the general case, the streaming velocity magnitude decreases with increasing polymer viscosity. Increasing relaxation time (elasticity) of the polymer solution leads to increasing streaming velocity magnitude as long as the relaxation time remains relatively small. It is also observed that the variation of the polymer viscosity and the relaxation time can change the pattern of streamlines.

Plasma plume evolution of a capillary discharge based pulsed plasma thruster: An optical diagnosis study

This paper studied the plasma plume evolution process of a capillary discharge based pulsed plasma thruster. Time-resolved imaging and optical emission spectroscopy were applied to investigate the plume morphology and plasma species characteristics. It showed that ionized particles (mainly C II and F II) were accelerated early in the pulse and neutral particles (mainly C I and F I) later. An optical time-of-flight (OTOF) method was developed using a photodiode array combined with narrow bandpass filters. The equivalent streaming velocity of the plasma plume was evaluated with the OTOF technique. Measurements of individual species showed that both the ionized and the neutral species could be effectively accelerated by gasdynamic forces, and the ionized particles could reach a higher velocity. A Doppler shift measurement of the plasma plume was also performed to compare it with the findings from the OTOF method. The plasma plume streaming velocity of a thruster with a discharge energy of 5 J was measured and found to be (25.34 ± 0.17) km/s (OTOF) and (22.36 ± 4.02) km/s (Doppler shift). In addition, differences between the operation processes of the capillary discharge based pulsed plasma thruster and the electromagnetic pulsed plasma thruster were analyzed.

Globular Clusters and Streaming Velocities: Testing the New Formation Channel in High-resolution Cosmological Simulations

Abstract The formation of globular clusters and their relation to the distribution of dark matter have long puzzled astronomers. One of the most recently proposed globular cluster formation channels ties ancient star clusters to the large-scale streaming velocity of baryons relative to dark matter in the early universe. These streaming velocities affect the global infall of baryons into dark matter halos, the high-redshift halo mass function, and the earliest generations of stars. In some cases, streaming velocities may result in dense regions of dark matter-free gas that becomes Jeans unstable, potentially leading to the formation of compact star clusters. We investigate this hypothesis using cosmological hydrodynamical simulations that include a full chemical network and the formation and destruction of H2, a process crucial for the formation of the first stars. We find that high-density gas in regions with significant streaming velocities is indeed somewhat offset from the centers of dark matter halos, but this offset is typically significantly smaller than the virial radius. Gas outside of dark matter halos never reaches Jeans-unstable densities in our simulations. We postulate that low-level (Z ≈ 10−3 Z ⊙) metal enrichment by Population III supernovae may enable cooling in the extra-virial regions, allowing gas outside of dark matter halos to cool to the cosmic microwave background temperature and become Jeans unstable. Follow-up simulations that include both streaming velocities and metal enrichment by Population III supernovae are needed to understand if streaming velocities provide one path for the formation of globular clusters in the early universe.

Local stress tensor calculation by the method-of-plane in microscopic systems with macroscopic flow: A formulation based on the velocity distribution function.

In this work, we developed a calculation method of local stress tensor applicable to non-equilibrium molecular dynamics (NEMD) systems, which evaluates the macroscopic momentum advection and the kinetic term of the stress in the framework of the Method-of-Plane (MoP), in a consistent way to guarantee the mass and momentum conservation. From the relation between the macroscopic velocity distribution function and the microscopic molecular passage across a fixed control plane, we derived a method to calculate the basic properties of the macroscopic momentum conservation law including the density, the velocity, the momentum flux, and the two terms of the stress tensor, i.e., the interaction and the kinetic terms, defined on a surface with a finite area. Any component of the streaming velocity can be obtained on a control surface, which enables the separation of the kinetic momentum flux into the advection and stress terms in the framework of MoP, and this enables strict satisfaction of the mass and momentum conservation for an arbitrary closed control volume (CV) set in NEMD systems. We validated the present method through the extraction of the density, velocity, and stress distributions in a quasi-one-dimensional steady-state Couette flow system and in a quasi-2D steady-state NEMD system with a moving contact line. We showed that with the present MoP, in contrast to the volume average method, the conservation law was satisfied even for a CV set around the moving contact line, which was located in a strongly inhomogeneous region.

Acoustofluidic dynamic interfacial tensiometry

The interfacial tension (IFT) of fluids plays an essential role in industrial, biomedical, and synthetic chemistry applications; however, measuring IFT at ultralow volumes is challenging. Here, we report a novel method for sessile drop tensiometry using surface acoustic waves (SAWs). The IFT of the fluids was determined by acquiring the silhouette of an axisymmetric sessile drop and applying iterative fitting using Taylor's deformation equation. Owing to physiochemical differences, upon interacting with acoustic waves, each microfluid has a different streaming velocity. This streaming velocity dictates any subsequent changes in droplet shape (i.e., height and width). We demonstrate the effectiveness of the proposed SAW-based tensiometry technique using blood plasma to screen for high leptin levels. The proposed device can measure the IFT of microscale liquid volumes (up to 1 μL) with an error margin of only ±5% (at 25 °C), which deviates from previous reported results. As such, this method provides pathologists with a solution for the pre-diagnosis of various blood-related diseases.

Scale-partitioned differential modeling of large-amplitude acoustic streaming

Classical techniques for modeling acoustic streaming rely on expansion of the flow about the relative slowness of the streaming velocity in comparison to the particle velocity. Rayleigh pioneered this approach nearly a century and a half ago for deducing streaming equations from the Navier-Stokes governing equations. Modern acoustofluidics applications do not generally admit the order of magnitude separation between flow components that is required in classical “slow streaming” approaches. We outline a theoretical technique that provides greater generality by using drastic spatiotemporal scale disparities to decompose the field equations. We achieve this with scale-partitioned differential operations. The framework is useful in general for modeling continuous nonlinear systems. We first provide brief examples of applying the framework to various media before exploring its use in the area of acoustofluidics specifically. We analyze large-amplitude (“fast”) bulk acoustic streaming in a one-dimensional setting. The resulting model explains empirically observed characteristic nonlinear streaming phenomena. From the model, we deduce a variety of bulk streaming properties, including a simple, algebraic upper bound on the maximum achievable streaming velocity in relation to the acoustic forcing. A comparative analysis is undertaken using experimental data from the recent literature.

Some First Stars Were Red: Detecting Signatures of Massive Population III Formation through Long-term Stochastic Color Variations

Abstract Identifying stars formed in pristine environments (Population III) within the first billion years is vital to uncovering the earliest growth and chemical evolution of galaxies. Population III galaxies, however, are typically expected to be too faint and too few in number to be detectable by forthcoming instruments without extremely long integration times and/or extreme lensing. In an environment, however, where star formation is suppressed until a halo crosses the atomic-cooling limit (e.g., by a modest Lyman–Werner flux, high baryonic streaming velocities, and/or dynamical heating effects), primordial halos can form substantially more numerous and more massive stars. Some of these stars will in turn be accreting more rapidly than they can thermally relax at any given time. Using high-resolution cosmological zoom-in simulations of massive star formation in high-z halos, we find that such rapidly accreting stars produce prominent spectral features that would be detectable by the James Webb Space Telescope. The rapid-accretion episodes within the halo lead to stochastic reprocessing of 0%–20% of the total stellar emission into the rest-frame optical over long timescales, a unique signature which may allow deep observations to identify such objects out to z ∼ 10–13 using mid- and wide-band NIRCam colors alone.

Ion Acoustic Shocks in a Weakly Relativistic Ion-Beam Degenerate Magnetoplasma

A theoretical investigation is carried out to study the propagation properties of ion acoustic shocks in a plasma comprising of positive inertial ions, weakly relativistic ion beam and trapped electrons in the presence of a quantizing magnetic field. By using the reductive perturbation technique, the Korteweg–de Vries-Burgers (KdVB) equation and oscillatory shocks solution are derived. The characteristics of such kinds of shock waves are examined and discussed in detail under suitable conditions for different physical parameters. The strength of the magnetic field, ion beam concentration and ion-beam streaming velocity have a great influence on the amplitude and width of the shock waves and oscillatory shocks. The results may be useful to study the characteristics of ion acoustic shock waves in dense astrophysical regions such as neutron stars.