Search

The identification of jets originating from quarks and gluons, often referred to as quark/gluon tagging, plays an important role in various analyses performed at the Large Hadron Collider, as Standard Model measurements and searches for new particles decaying to quarks often rely on suppressing a large gluon-induced background. This paper describes the measurement of the efficiencies of quark/gluon taggers developed within the ATLAS Collaboration, using √s = 13 TeV proton–proton collision data with an integrated luminosity of 140 fb−1 collected by the ATLAS experiment. Two taggers with high performances in rejecting jets from gluon over jets from quarks are studied: one tagger is based on requirements on the number of inner-detector tracks associated with the jet, and the other combines several jet substructure observables using a boosted decision tree. A method is established to determine the quark/gluon fraction in data, by using quark/gluon-enriched subsamples defined by the jet pseudorapidity. Differences in tagging efficiency between data and simulation are provided for jets with transverse momentum between 500 GeV and 2 TeV and for multiple tagger working points.

An understanding of the behaviour of the D or He fuel used in tokamak discharges is essential in analyses such as modelling edge and divertor transport and the erosion of the vessel walls. However, poor agreement is found between measurements made on the JET tokamak and collisional-radiative models used to predict the hydrogen-like D and He line intensities. The range of temperatures of the plasmas emitting the radiation is also limited, in contrast to that for many impurities for which a wide range is possible. This is particularly so for He II whose line intensities tend to have the same near-constant ratios in most pulses, suggesting that the emission originates in plasma regions with very similar electron temperatures. To gain understanding and to allow quantitative comparisons with theoretical models, extensive observations of the VUV Lyman series have been made, for all discharge scenarios run during three He campaigns. Those for He discharges in both JET ITER-like wall (JET-ILW) and JET C (JET-C) campaigns are presented here. He discharges have the advantage of fewer impurities resulting in less complex spectra than when D is used as the fuel. However, the characteristics of the observed discrepancies are similar in both species, allowing He to be used as a proxy for D in order to gain understanding of the discrepancy. In addition, the study of He avoids the complication of molecular species contributing to the level populations. Opacity effects are also expected to be less severe in He discharges. Nevertheless, so as to ensure that the measurements are not unduly affected by opacity, comparisons have also been made with emission from Balmer and Paschen series members. Measurements of both line intensities and their ratios are presented for all-pulse surveys and for individual pulses. In exceptional cases in which the He emission is intense a dependence on the He II line intensity is demonstrated. The discrepancy between these measurements and the theoretical models is illustrated. [ABSTRACT FROM AUTHOR]

Hybrid composites made of natural fibers are replacing composites made of synthetic fibers, which is better for the environment. In this study, a Cotton/Corn Hybrid Composite was prepared using compression moulding and evaluated the Abrasive Water Jet Machining (AWJM) process variables on surface quality. The AWJM investigations were conducted using experimental design approaches, with variables including water pressure, nozzle transfer speed, and standoff distance. Among these variables, it was determined that nozzle transfer speed had the most influential impact on surface quality. The optimal machining parameters P2, s1, and d1 were identified, resulting in a surface roughness of 4.459 μm. This demonstrates that accomplishing better surface quality is attainable through the suitable parameter selection. Further, the prediction model's efficiency was validated by establishing a strong relationship between the experimental, predicted, and validated surface roughness values. This highlights the model's reliability in predicting and optimizing surface quality in the AWJM process. [ABSTRACT FROM AUTHOR]

To enhance the service life of shipping equipment and minimize surface wear, this study employs biomimetic principles, integrating fitted structures with jet dynamics to model three configurations: non-smooth structures, single jet structures, and non-smooth jet-coupled structures. We utilized the SST k-ω turbulence model for numerical simulations to investigate the drag reduction characteristics of these structural models. By varying the jet angle and speed, we analyzed the changes in viscous resistance, pressure differential resistance, and drag reduction rates at the wall surface. Furthermore, the mechanisms of compressive stress, velocity fields, vortex structures, and shear stress on drag-reducing surfaces were elucidated, revealing how these factors contribute to drag reduction in non-smooth jet-coupled structures. The results indicate that the non-smooth jet-coupled structure exhibits superior drag reduction performance at a main flow field velocity of 20 m/s. As the jet velocity increases, the viscous drag on the surface of the non-smooth jet-coupled structure decreases, while the pressure differential drag increases. Conversely, variations in the jet angle have a minimal effect on viscous drag but lead to a reduction in pressure differential drag. Specifically, when the jet velocity is set at 1 m/s, and the jet angle is 60°, the drag reduction achieved by the non-smooth jet-coupled structure peaks at 7.48%. Additionally, the non-smooth jet-coupled structure features a larger area characterized by low shear stress, along with an increased boundary layer thickness at the bottom; this configuration effectively reduces surface velocity and consequent viscous drag. [ABSTRACT FROM AUTHOR]

In order to explore the drag reduction characteristics of different jet parameters in the bulb through pump, the bionic design was carried out for the shark gills, and the model of the bulb through the pump with a jet port at the front end of the bulb body was established, and the influence mechanism of the placement position, jet velocity and number of jet ports on the flow field of the bulb through the pump was studied by CFX. The results show that the near-wall main stream collides with the jet, and the axial momentum transmitted by the main stream to the jet weakens the axial velocity of the near-wall main stream. The radial momentum of the jet to the main stream increases the radial velocity of the near-wall mainstream, and lifts the near-wall high-velocity zone away from the bulb body, so that the near-wall medium and low velocity bands are widened, the high-velocity zone is contracted, and the wall shear stress is reduced. The calculation predicts that the drag reduction effect is up to 23.069%, the head is increased by 0.083 m, and the efficiency is increased by 1.729%, which can provide guidance for the optimal design and efficient operation of the bulb through-flow pump. [ABSTRACT FROM AUTHOR]

Introduction: This work explores the use of eXplainable artificial intelligence (XAI) to analyze a convolutional neural network (CNN) trained for disruption prediction in tokamak devices and fed with inputs composed of different physical quantities. Methods: This work focuses on a reduced dataset containing disruptions that follow patterns which are distinguishable based on their impact on the electron temperature profile. Our objective is to demonstrate that the CNN, without explicit training for these specific mechanisms, has implicitly learned to differentiate between these two disruption paths. With this purpose, two XAI algorithms have been implemented: occlusion and saliency maps. Results: The main outcome of this paper comes from the temperature profile analysis, which evaluates whether the CNN prioritizes the outer and inner regions. Discussion: The result of this investigation reveals a consistent shift in the CNN's output sensitivity depending on whether the inner or outer part of the temperature profile is perturbed, reflecting the underlying physical phenomena occurring in the plasma. [ABSTRACT FROM AUTHOR]

A fraction of the active supermassive black holes at the centers of galaxies in our Universe are capable of launching extreme kiloparsec-long relativistic jets. These jets are known multiband (radio to γ-ray) and multimessenger (neutrino) emitters, and some of them have been monitored over decades at all accessible wavelengths. However, several open questions remain unanswered about the processes powering these highly energetic phenomena. These jets intrinsically produce soft-to-hard X-ray emission that extends from E > 0.1 keV up to E > 100 keV, and simultaneous broadband X-ray coverage, combined with excellent timing and imaging capabilities, is required to uncover the physics of jets. Indeed, truly simultaneous soft-to-hard X-ray coverage, in synergy with current and upcoming high-energy facilities (such as IXPE, COSI, CTAO, etc.) and neutrino detectors (e.g., IceCube), would enable us to disentangle the particle population responsible for the high-energy radiation from these jets. A sensitive hard X-ray survey (F20-80 keV < 10-15erg cm-2 s-1) could unveil the bulk of their population in the early Universe. Acceleration and radiative processes responsible for the majority of their X-ray emission would be pinned down by microsecond timing capabilities at both soft and hard X-rays. Furthermore, imaging jet structures for the first time in the hard X-ray regime could unravel the origin of their high-energy emission. The proposed Probe-class mission concept High Energy X-ray Probe (HEX-P) combines all these required capabilities, making it the crucial next-generation X-ray telescope in the multi-messenger, time-domain era. HEX-P will be the ideal mission to unravel the science behind the most powerful accelerators in the Universe. [ABSTRACT FROM AUTHOR]

Sediment management is a significant part of the decision-making process that hydraulic engineers need to undertake as it has a direct bearing on the environment. Sediment dredging from around intake structures and reservoirs impose a high operating cost. Jets can efficiently remove large quantities of sediment at low operational costs. This study assesses the scouring pattern development by changing nozzle parameters to achieve maximum scouring conditions. Toward this end, scour holes induced by jets generated using the nozzles with four inner angles (30°, 45°, 60°, and 90°) are tested on a cohesionless sediment bed. The experimental results show that the inner nozzle angle, α, and the densimetric Froude number, F0, affect the scour pattern. This work illustrates that the scour hole dimensions grow with increasing α and F0. Based on the velocity measurements, for the range of jet discharges considered herein, the relative velocity Um/U0 is increased by 20%–25% for the nozzle with α = 90° compared to the nozzle with α = 30°. [ABSTRACT FROM AUTHOR]

The effect of aerodynamic noise from high-speed trains on residents living near railway lines is a critical issue. The pantograph cavity is considered to be a major source of aerodynamic noise. To address this problem, this study proposes the application of jetting at the leading edge of the cavity, directly targeting noise reduction at its source. The large eddy simulation approach is used for flow calculations, and the Ffowcs Williams and Hawkings aeroacoustic analogy is adopted for far-field acoustic predictions. Orthogonal designs and the backpropagation algorithm optimized by the genetic algorithm (BP-GA) is used to explore the effects of jetting factors on noise and identify the optimal parameters. Orthogonal design analysis shows that the most influential among the factors is jet orifice diameter, followed by jet velocity and jet angle. The use of the BP-GA algorithm for optimization reveals that the optimal jet parameters are jet velocity of 118.28 m/s, jet angle of 3.17°, and jet orifice diameter of 76.74 mm. The algorithm predicts a minimum noise level of 91.04 dB, which is close to the simulated noise level of 90.74 dB. The jetting process achieves a maximum noise reduction of 4 dB. Results demonstrate that the proposed method for cavity leading edge jetting effectively reduces turbulent kinetic energy and horseshoe-shaped vortices in the cavity, leading to noise reduction. This method also minimizes the effects of aerodynamic noise on distant areas, such as waiting areas and residential buildings. This work provides a theoretical basis for increasing high-speed train speeds. [ABSTRACT FROM AUTHOR]

In this study, a disk-type bluff body was installed at the upper part of a nozzle exit, and the circular jet inside the nozzle was controlled using a dielectric barrier discharge (DBD) plasma actuator (DBD-PA). The effects of the changes in the excitation frequency of the jet induced by the DBD-PA on the jet diffusion were elucidated. The experiments included visualization of the jet cross-section, particle image velocimetry analysis, and velocity measurements using an I-type hot-wire anemometer. When the DBD-PA was driven at a specific burst frequency (900–1400 Hz), a lock-in phenomenon occurred, in which the frequency of vortices generated in the initial jet coincided with the burst frequency. This lock-in phenomenon suppressed the merging of vortices by generating vortices at regular intervals. When vortex merging was suppressed, the jet was less likely to be entrained into the recirculation flow generated by the bluff body, thereby increasing the downstream jet width and average flow rate. [ABSTRACT FROM AUTHOR]

Electromagnetic pulse welding (EMPW) is commonly used for welding copper and aluminum alloy. The welding gap is important in the EMPW process. The research focused on the effect of welding gap on the welding process and the mechanical property of joints. During the EMPW experiments, the deformation, collision, and metal jet were recorded with a high-speed camera. The joint mechanical property was tested. SEM and EDS were employed to examine the bonding interface. Results indicated that the welding gap length did not significantly influence the aluminum alloy plate motion behavior when it was long enough. With the welding gap width increasing, the collision velocity initially increased and subsequently decreased, and the angle between the two plates when they first collided increased continuously. The intensity and duration of the metal jet and the joint mechanical properties also increased first and then decreased. The welding marks widened first and then narrowed. [ABSTRACT FROM AUTHOR]

In the water entry process of hollow projectiles, the formation of high-speed water jets is a crucial factor influencing their water entry. In order to study the influence of the through-hole aperture of hollow projectiles on jet and water entry characteristics, a vertical water entry simulation model for hollow projectiles with different apertures was established, and the intra-hole pressure characteristics and the difference in cavity development among projectiles with different apertures were compared. The results show that the aperture ratio is related to the intensity of intra-hole pressure at the moment of initial collision. The height and velocity of the jet decrease with an increase in the aperture ratio, which is related to the intra-hole pressure gradient. Additionally, the intensity of the pressure gradient diminishes as the aperture ratio increases. This study briefly describes the development of the cavitation phenomenon in hollow projectiles and analyzes the influence of the aperture ratio on the cavitation phenomenon. The results indicate that as the aperture ratio increases, the amount of vapor produced by the projectile decreases, leading to an earlier closing of the cavity.

AbstractDensity stratification in a large enclosure is a crucial phenomenon to heat transfer and sustainable passive heat removal of a sodium fast reactor during reactivity transients. However, engineering turbulence models were identified to have unsatisfactory performance in predicting propagation of a stratified front. Yet, the scarcity of high-resolution data for stratification hampers the development of models. To explor e applications of leveraging direct numerical simulation (DNS) data to support turbulence model development, this work conducted DNS using NekRS to study a long stratification transient in the High-Resolution Jet (HiRJET) experimental facility. This work considers an experiment run where light fluid is injected into a tank containing a denser fluid with a relative density difference of 1.5%. Formation of the stratified layer is identified as impingement of the buoyant jet promoting mixing of the two fluids. Based on the transient statistics, transport of the concentration can be characterized by regions with dominating effects of turbulent mixing, buoyant dissipation, and molecular diffusion, respectively, as moving away from the elevation of jet impingement. Concentration near the stratified front also exhibits oscillation at Brunt-Väisälä frequency. Preliminary validation of the simulation showed encouraging agreement of the concentration distribution with the reference experiment. [ABSTRACT FROM AUTHOR]

This study demonstrates that temporally developing lobed jets can qualitatively reproduce the diffusion performance in the fully developed states of spatially developing lobed jets in laboratory experiments. The jet exit geometries, Reynolds number (= 70 , 000) , and turbulence intensity (3% of mean velocity) were set to be the same across the temporally and spatially developing jets. Four types of jet flows were tested, one being a round jet and three being lobed jets with different numbers or curvatures of lobes, referred to as 6L, 6S, and 3L, respectively. The half-width of the mean streamwise velocity distributions and centerline mean streamwise velocity of the four jets in the developed states were consistent between the numerical simulations and experiments. The round jet displayed the highest diffusion performance, followed by 3L, while 6L and 6S were the smallest and were comparable with each other. Despite such consistency in the developed states, the diffusion performance and formation of the streamwise swirling flows did not agree between the numerical and experimental results. These results suggest that unique large-scale structures corresponding to the initial conditions are reproduced in temporally developing jets, which is in good agreement with the spatially developing lobed jets. Therefore, the current study demonstrated that the temporally developing simulations can reproduce similar diffusion processes to those of the spatially developing ones. [ABSTRACT FROM AUTHOR]

The splashes of a highly viscous fluid (glycerol) resulting from its pulsed displacement from a gap between two rapidly approaching disks are studied. It is found that, outside the disks, the splash has the form of a thin film bounded by an annular rim. A physical model of the splash is formulated, and analytical solutions describing its trajectory are given. The calculation results are compared with experimental data. The effects of fluid viscosity, surface tension, and film breakdown are analyzed. It is shown that the key influence on the splash development scenarios is exerted by surface tension of the film connecting the rim to the disks. [ABSTRACT FROM AUTHOR]

To address the scientific inquiry regarding the dynamic mechanism of deformation of droplets on the jet surface, this study establishes a stochastic differential equation describing deformation of a droplet on a uniform jet surface, considering the affine deformation of a semi-ellipsoidal droplet driven by the pulsation velocity of the jet. The results indicate that the equilibrium point set of the model conforms to an inverse proportional function concerning the major and minor axes of the droplet. Additionally, the assumption of the physical model is satisfied only when the droplet position parameter . The solution process, initialized with the equilibrium point set, tends to reach the state of mean square instability within a very short duration. For dimensionless initial semi-minor axes of the droplet below 0.1 and within the constraint of the equilibrium point set, the probability of the droplet being in a stretched state during the later stages of deformation ranges between 60 and 65%. In this model, during the late stage of droplet deformation, the dimensionless semi-minor axis of the droplet approaches zero. Thus, when the droplet is in the stretched state, it is close to breaking. During retraction, the length of semi-major axis of the droplet fluctuates and gradually decreases. However, in the stretched state, the length of semi-major axis of the droplet increases rapidly, with its growth rate accelerating with time. [ABSTRACT FROM AUTHOR]

The SOLPS‐ITER3.0.8 code with new Grad‐Zhdanov module was applied for predictive modeling of tritium plasma and deuterium‐tritium mixture in tokamak JET. The moderate power scenario of shot JPN #85278 modeled earlier for deuterium plasma was taken as a starting point. Effect of puffing increase, which was applied in experiment, on divertor conditions and inter‐ELM tungsten sputtering for both working gases and on isotope separation in their mixture is analyzed. Both for attached and for semi‐detached outer targets, the tritium plasma shows moderate increase in SOL width compared to deuterium one. The tungsten sputtering at the outer target in the inter‐ELM period for tritium is an order of magnitude bigger than that for deuterium. The D–T separation in the D–T mixture is moderate. [ABSTRACT FROM AUTHOR]

The hydrogenic two‐point model (H‐2PM), an analytical model for the scrape‐off layer that predicts a common electron and ion temperature and density along a flux tube from a target temperature and density, is adapted to a single‐species helium (He) model, preserving the 2PM assumptions and analytical nature. Across a range of densities and heating powers, the predicted Te$$ {T}_e $$ is within 20eV$$ 20\kern0.3em \mathrm{eV} $$ of upstream measurements by high‐resolution Thomson scattering (HRTS) for low‐confinement He plasmas performed in JET ITER‐like wall (JET‐ILW). For high‐recycling conditions, He‐2PM predictions of ne$$ {n}_e $$ were within 10% of the Li‐beam diagnostic measurements, excluding the near‐SOL, when assuming Zeff=1$$ {Z}_{\mathrm{eff}}=1 $$, suggesting the divertor SOL was not fully ionised in the JET‐ILW He plasmas. [ABSTRACT FROM AUTHOR]

The fundamental plane of black hole activity is a very important tool to study accretion and jets. However, we found that the SEDs of AGNs and XRBs are different in the 2–10 keV energy band, and it seems inappropriate to use 2–10 keV X-ray luminosities to study the fundamental plane. In this work, we use the luminosity near the peak of the blackbody radiation of the active galactic nuclei and black hole binaries to replace the 2–10 keV luminosity. We re-explore the fundamental plane of black hole activity by using the 2500 A ˚ luminosity as the peak luminosity of the blackbody radiation of AGNs and 1 keV luminosity as the peak luminosity of the blackbody radiation of XRBs. We compile samples of black hole binaries and active galactic nuclei with luminosity near the peak luminosity of blackbody radiation and study the fundamental plane between radio luminosity ( L R ), the peak luminosity of blackbody radiation ( L peak ), and black hole mass ( M BH ). We find that the radio–peak luminosity correlations are L 5 GHz / L Edd ∝ (L 2500 A ˚ / L Edd) 1.55 and L 5 GHz / L Edd ∝ (L 1 keV / L Edd) 1.53 for AGN and XRB, respectively, in the radiatively efficient sample, and L 5 GHz / L Edd ∝ (L 2500 A ˚ / L Edd) 0.48 and L 5 GHz / L Edd ∝ (L 1 keV / L Edd) 0.53 in the radiatively inefficient sample, respectively. Based on the similarities in radio–peak correlations, we further propose a fundamental plane in radio luminosity, the peak luminosity of blackbody radiation, and black hole mass, which is radiatively efficient: log L 5 GHz = 1. 57 − 0.01 + 0.01 log L peak − 0. 32 − 0.16 + 0.16 log M BH − 27. 73 − 0.34 + 0.34 with a scatter of σ R = 0.48 dex, and radiatively inefficient: log L 5 GHz = 0. 45 − 0.01 + 0.01 log L peak + 0. 91 − 0.10 + 0.12 log M BH + 12. 58 − 0.38 + 0.38 with a scatter of σ R = 0.63 dex. Our results are similar to those of previous studies on the fundamental plane for radiatively efficient and radiatively inefficient black hole activity. However, our results exhibit a smaller scatter, so when using the same part of blackbody radiation (i.e., the peak luminosity of the blackbody radiation), the fundamental plane becomes a little bit tighter. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Fermi bubbles and the eROSITA bubbles around the Milky Way Galaxy are speculated to be the aftermaths of past jet eruptions from a supermassive black hole in the galactic center. In this work, a 2.5D axisymmetric relativistic magnetohydrodynamic (RMHD) model is applied to simulate a jet eruption from our galactic center and to reconstruct the observed Fermi bubbles and eROSITA bubbles. High-energy non-thermal electrons are excited around forward shock and discontinuity transition regions in the simulated plasma distributions. The γ -ray and X-ray emissions from these electrons manifest patterns on the skymap that match the observed Fermi bubbles and eROSITA bubbles, respectively, in shape, size and radiation intensity. The influence of the background magnetic field, initial mass distribution in the Galaxy, and the jet parameters on the plasma distributions and hence these bubbles is analyzed. Subtle effects on the evolution of plasma distributions attributed to the adoption of a galactic disk model versus a spiral-arm model are also studied. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A sign which regularly appears on the door of St Mary's Church in Whitby, North Yorkshire, alerts visitors that Dracula is not buried in the churchyard. Dracula arrives in Whitby in Bram Stoker's fiction, exits the stage and finally turns to dust near his Transylvanian castle. The sign, however, underscores Dracula's enduring association with Whitby, forged by Stoker's visit to the town in the summer of 1890. Just over one hundred years after Stoker's visit, Jo Hampshire, a Goth from Barnsley, West Yorkshire, inspired by Dracula's association with the town, arranged a Goth visit to Whitby, after posting an advertisement in NME magazine. The gathering launched what would become Whitby Goth Weekend (WGW). Thirty years after Hampshire's visit, Whitby attracts a range of Goth/ic tourists, a term which here denotes Goths, the subcultural movement dating from the 1970s, and those who are attracted to the Gothic from literary tourists to Instagrammers. The article explores how Whitby, particularly its East Cliff, inspired by Stoker's vision, operates as Goth/ic tourist space and, in particular, how it presents and is experienced as Goth/ic theatre. It reads the Whitby passages from Dracula in the context of Stoker's experience of Gothic and melodramatic performance at London's Lyceum theatre where Stoker worked as business manager. It traces the establishment of WGW in 1994, its evolution and adaptation in the age of social media, and how Whitby has developed to become a place of Goth/ic experience, performance and cultural contestation. [ABSTRACT FROM AUTHOR]

Liquid nitrogen jet is expected to provide a new idea for the breaking of deep dry hot rock due to its low temperature. In order to study the characteristics of heterogeneous temperature and stress fields during liquid nitrogen jet impingement, the downhole flow and stress characteristics induced by liquid nitrogen jet were studied by a thermal-hydraulic-mechanical coupling model. The results showed that under the same conditions, the potential core and the maximum velocity of liquid nitrogen jet were higher than water jet. The liquid nitrogen jet had a larger region of high turbulent kinetic energy, and the heat transfer efficiency with the bottom rock was obviously higher than water jet. Compared with the water jet, the liquid nitrogen jet formed a tensile stress zone in the bottom rock. The research was expected to provide a theoretical basis for the rock breaking mechanism of liquid nitrogen jet. [ABSTRACT FROM AUTHOR]

In urban drainage systems, falling sewage in drop structures expedites the mass transfer of hydrogen sulfide (H2S) and oxygen (O2). This process is important for sewer odor and corrosion control; however, direct experiments and relevant knowledge are limited. This study conducted laboratory experiments using two typical forms of falling sewage: free-falling jet and attached-falling jet. The results show that mass transfer coefficient KL and concentration deficit ratio r (the ratio of upstream-to-downstream gas concentration deficiency) increase with an increase of sewage drop height (0.2–1.4 m) and with a decrease of flow rate (0.9–2.0 L/min). Nonlinear correlations between r and the hydraulic parameters were proposed. The free-falling jet contributed about 40% more mass transfer than the attached-falling jet. The mass transfer rate in free-falling drop structures of this study was 3–13 times that in gravity sewers without drop structures. In addition, O2 is an appropriate surrogate gas for studying H2S mass transfer. Finally, the mass transfer of O2 in a prototype drop structure was estimated: if the drop height is <3 m , the jet may not break up, the mass transfer at the jet surface can be neglected, and almost all the mass transfer happens at the bottom pool of the drop structure; however, if the drop height is >6 m , falling droplets are the main (>80%) contributor. This study provides a tool for estimating the mass transfer in drop structures, which can optimize the design of drop structures to control sewer odor and pipe corrosion. [ABSTRACT FROM AUTHOR]

The technology to jet print metal lines with precise shape fidelity on diverse substrates is gaining higher interest across multiple research fields. It finds applications in additively manufactured flexible electronics, environmentally friendly and sustainable electronics, sensor devices for medical applications, and fabricating electrodes for solar cells. This paper provides an experimental investigation to deepen insights into the non-contact printing of solder lines using StarJet technology, eliminating the need for surface activation, substrate heating, curing, or post-processing. Moreover, it employs bulk metal instead of conventional inks or pastes, leading to cost-effective production and enhanced conductivity. The effect of molten metal temperature, substrate temperature, standoff distance, and printing velocity was investigated on polymer foils (i.e., PET sheets). Robust printing parameters were derived to print uniform, bulge-free, bulk metal lines suitable for additive manufacturing applications. The applicability of the derived parameters was extended to 3D-printed PLA, TPU, PA-GF, and PETG substrates having a much higher surface roughness. Additionally, a high aspect ratio of approx. 16:1 wall structure has been demonstrated by printing multiple metal lines on top of each other. While challenges persist, this study contributes to advancing additively manufactured electronic devices, highlighting the capabilities of StarJet metal jet-printing technology. [ABSTRACT FROM AUTHOR]

The current research examines the combined effects of solar energy and thermal buoyancy around a laminar jet placed in a porous medium. The governing boundary layer equations are dimensionalized by using appropriate dimensionless variables. The numerical solution of the dimensionless boundary layer equations is obtained using the finite difference method. The impact of physical parameters, which are Darcy number, dimensionless porous medium inertia coefficient, Prandtl number, radiation parameter, and dimensionless fluid's absorption parameter, on velocity and temperature profile, is shown graphically, while the influence of the above parameters on the heat transfer rate is presented in tabular form. It is keenly observed that for Darcy number velocity profile decreases while reverse behavior is noted for temperature distribution. For the dimensionless radiation parameter, both the velocity and temperature profile decrease. The main novelty of the current work is to improve the thermal performance of natural convection heat transfer system in the presence of thermal radiation placed in porous medium.

Abstract With the continuous improvement of various armor protection technologies, the armor protection performance has increased significantly, and then the damage performance requirements of armor-piercing ammunition have also increased. In order to improve the penetration ability of the liner, a new three-layer liner structure is designed in this paper. The jet forming process was simulated by AUTODYN software. The mechanism of shaped jet forming of three-layer liner was studied. The reason why the penetration depth of three-layer liner was higher than that of ordinary liner was explained. The influence of three-layer liner on the propagation of detonation wave and the change of pressure when detonation wave acted on liner were found, which provided a new idea for improving the penetration depth of jet. The influence of liner material, cone angle and stand-off on jet forming and penetration was also studied by orthogonal optimization experiment, and the structural parameters with the best penetration performance were obtained. The results show that the pressure at the convergence point increases first and then decreases during the formation of the jet of the three-layer liner. The pressure at the convergence point when the three-layer liner material is from low impedance to high impedance from the outside to the inside is much larger than the pressure at the convergence point from high impedance to low impedance. When the three-layer liner material is Al 2024-Copper–Tantalum from the outside to the inside, the pressure at the convergence point of the three-layer liner at different times is higher than that of the double-layer liner and the single-layer liner. Reasonable matching of different impact impedance materials in the three-layer liner can greatly improve the pressure value of the detonation wave acting on the cone liner. The maximum pressure at the convergence point on the axis is 39.10 GPa, which is 22.00% higher than that of the double-layer liner at the convergence point, and 53.03% higher than that of the single-layer liner at the convergence point. The orthogonal design test scheme is simulated and analyzed. The penetration depth is taken as the observation index, and the range analysis is adopted. The results show that the material matching of the three-layer liner has the greatest influence on the depth of the jet penetrating the target plate, followed by the cone angle of the three-layer liner. Relatively speaking, the stand-off has the least influence on the result. Reasonable matching of materials with different impact impedances in the three-layer liner can maximize the penetration depth of the jet into the target plate.

Analysis of comparable discharges fuelled by either deuterium or protium reveals a clear relationship between the isotope mass and the H-mode density limit. Notably, the density limit is significantly lower in protium, showing a reduction of up to 35 % compared to identical deuterium plasma conditions. Within mixed H-mode density limit (HDL) plasmas, the maximum achievable density, or H-mode density limit, decreases with increasing protium concentration, denoted as cH. For instance, the highest corresponding maximum Greenwald fraction (fGW) of about 1.02 was observed in the pulse with the lowest cH value of 4.4 %. This fGW decreases to 0.96 at cH = 48 %. The average atomic mass, A¯, of the plasma species decreases in these pulses from the value of 1.96 (cH = 4.4 %) down to 1.52 (cH = 48 %). Interestingly, the maximum achievable density appears to be largely unaffected by the applied power value, regardless of whether deuterium or protium is used, as well as under mixed H/D fuelling conditions.Additionally, the measured Greenwald fractions are agreed with a heuristic model based on the SOL pressure threshold of an MHD instability, as proposed by Goldston. This comparison, especially concerning the model’s dependence on isotopic mass, shows full consistency between the measured and predicted Greenwald fractions.

Turbulent water jets remain a critical study area, particularly the relation of the water flow with air entrainment and its role in energy dissipation at different hydraulic structures. Plunge pools, formed by the impact of jets on water cushions, play a pivotal role in energy dissipation. Understanding the complex flow dynamics within these pools is essential for designing efficient hydraulic structures. In this research, we present a comprehensive investigation of different numerical simulations, defining two-phase (air-water) in different ways, and them compare with experimental measurements. The primary objective is to analyze the pressure distribution at the bottom of a plunge pool induced by a vertical jet and understand the importance of accurately defining air-water flow in the dynamics of the jet into the pool. Our study bridges the gap between empirical data and computational modeling, shedding light on the intricate behavior of such flows with different method-based solvers: VOF, sub-grid, and multi-phase Euler. Various computational domains, mesh configurations, and analyses spanning different time periods, frequencies, and scales were considered. [ABSTRACT FROM AUTHOR]

Reduction of gas turbine (GT) carbon emissions relies on a strategy for fueling the engines with pure or blended hydrogen. The major technical challenges to solve are (i) the adjustments to the engine and in particular the combustion chamber and (ii) a series of issues to solve to guarantee safe operations. In fact, compared to natural gas, hydrogen fueling implies higher risks of explosion in case of leak in the turbine enclosure and a more careful design of the ventilation system. Thus, a deeper comprehension of hydrogen leak scenarios is needed to adjust the safe design strategy of the enclosure. To this aim, a series of numerical investigations was carried out to understand how different methane-hydrogen blends (from pure methane to pure hydrogen) behave when leaking from a pipeline with fuel pressure that span from 1.5 to 4.5 MPa. The different fuel blends' leaks in form of underexpanded jets were studied under different cross-flow ventilation conditions, with ventilation velocity spanning from 0 m/s to 5 m/s. When compared to pure methane, the outcome is a three times longer penetration distance for pure hydrogen axisymmetric flammable clouds, whereas in cross-flow conditions a more complex three-dimensional behavior was found, potentially opening a safety-related concerns discussed in the paper. [ABSTRACT FROM AUTHOR]

The Joint European Torus (JET) is playing an important role in preparing for the operation of the future world's largest tokomak, ITER. In this respect, the tritium campaign (C40) and second deuterium–tritium experiment (DTE2, C41) took place in the JET during the years 2021 and 2022. In this work, a corresponding irradiation scenario was utilized for the activation calculations of eight material foils located at the JET outer long-term irradiation station (OLTIS). Neutron-induced activities and dose rates at a 30 cm distance after shutdown at specified cooling intervals were calculated with the FISPACT-II code, employing the EAF-2010 nuclear and TENDL-2021 data libraries. The Monte Carlo MCNP6.2 particle transport code equipped with the FENDL-3.1d nuclear data library was used for the calculation of the neutron flux densities. [ABSTRACT FROM AUTHOR]

Microfine low-rank coals are subject to metamorphic changes that hinder their floatability, impeding their clean and efficient utilization. The objective of this study was to refine the jet-slurry technique to enhance the floatability of microfine low-rank coals. Furthermore, advanced methods including Focused beam reflectance measurement (FBRM), high-sensitivity microelectromechanical balancer (DCAT), Fourier transform infrared spectrometer (FTIR), and scanning electron microscope (SEM) were employed to dissect the physicochemical effects of jet slurring on microfine low-rank coal particles. The study found that as the concentration of microfine coal particles increased, surface reagent adsorption initially rose and then fell with greater feed volumes. In contrast, adhesion forces displayed an inverse trend. Optimal results were achieved with a feed volume set at 25 L/min. This phenomenon is attributable to multiple regulatory factors. Within certain limits, intensifying conditioning promotes particle agglomeration, curtails fine gangue mineral coverage, boosts sodium dodecyl sulfate (SDS) adsorption, diminishes microfine coal wettability, and better kerosene-coal particle mixing. However, at excessive jet speeds (30 L/min), substantial physical pressure variances and mechanical dispersion forces arise, undermining SDS or kerosene’s chemical adsorption to coal or modified coal, thus reducing reagent attachment. The aforementioned study demonstrates that within certain parameters, jet slurring significantly betters coal-gangue separation, thereby amplifying the flotation efficacy of microfine low-rank coals. This research offers strategic insights into microfine low-rank coal flotation processes and lays a theoretical groundwork for the selection of suitable techniques and reagents. [ABSTRACT FROM AUTHOR]

This study, conducted over 4 years in Baghdad, Iraq, aimed to determine the importance of ureteric jet assessment in medical expulsive therapy (MET) for distal ureteral stones. A total of 156 patients with distal ureteral stones (≤ 10 mm) participated, and their ureteric jets were observed using a color Doppler scanner before and after 2 weeks of MET. The main focus was the success rate of stone expulsion. Our results showed that 50% of patients had detectable ureteric jets after 2 weeks of MET, and 21.8% experienced successful stone expulsion. After 4 weeks, 23.7% achieved stone expulsion, while 54.5% still had remaining stones. Patients who had a positive baseline ureteric jet were significantly more likely to successfully expel their stones. This study highlights the importance of monitoring ureteric jet movement in MET for distal ureteral stones. [ABSTRACT FROM AUTHOR]

Natural fiber hybrid composites are replacing synthetic fiber composites, which improves environmental cleanliness. In this investigation, a compression molding process was used to produce a Banana/Sisal Hybrid Composite (BSHC) and the influence of Abrasive Water Jet Machining (AWJM) process parameters on surface quality was studied. The AWJM experiments were conducted using the design of experiment techniques, with parameters such as water pressure (P), nozzle transfer speed (d), and standoff distance (s). During the AWJM process, P was identified as the most significant parameter influencing surface quality. The optimum machining parameters (P3, d1, s1) provide better surface quality which produces a surface roughness of 10.1 μm. The experimental surface roughness values have a better correlation with the predicted surface roughness which shows the efficiency of the prediction model. [ABSTRACT FROM AUTHOR]

A fraction of the active supermassive black holes at the centers of galaxies in our Universe are capable of launching extreme kiloparsec-long relativistic jets. These jets are known multiband (radio to γ-ray) and multimessenger (neutrino) emitters, and some of them have been monitored over decades at all accessible wavelengths. However, several open questions remain unanswered about the processes powering these highly energetic phenomena. These jets intrinsically produce soft-to-hard X-ray emission that extends from E>0.1keV up to E>100keV, and simultaneous broadband X-ray coverage, combined with excellent timing and imaging capabilities, is required to uncover the physics of jets. Indeed, truly simultaneous soft-to-hard X-ray coverage, in synergy with current and upcoming high-energy facilities (such as IXPE, COSI, CTAO, etc.) and neutrino detectors (e.g., IceCube), would enable us to disentangle the particle population responsible for the high-energy radiation from these jets. A sensitive hard X-ray survey (F20−80keV

Langmuir probe measurements in neutral beam injection (NBI) heated, low-confinement mode plasmas in JET ITER-like wall showed that the current to the divertor targets, Idiv, in helium (He) plasmas was up to 70% lower on the low-field side (LFS) than in otherwise identical deuterium (D) plasmas. The edge plasma density at which the rollover of Idiv occurred i.e. the onset of detachment, was 10% higher in He plasmas on both the LFS and high-field side (HFS). The density of Idiv rollover increases by 25% for He when the NBI power increases 1MW to 5MW. The total radiated power was similar in He and D plasmas for densities below the Idiv rollover. At densities above the Idiv rollover density, the total radiated power and power from within the separatrix are higher in He, reducing the power across the separatrix and subsequently Idiv,LFS. In He plasmas, the peak radiated power was observed within the confined region above the X-point in tomographic reconstructions from bolometry.

A detailed obtaining of the expressions for the scalar components of the canonical form on higher order frame bundles over a smooth manifold has been done. The canonical form on the frame bundle of order p + 1 over an n-dimensional smooth manifold is a vector-valued differential 1-form with values in the tangent space to the p-th order frame bundle over the n-di­mensional arithmetical space at the unit of the p-th order differential group. The scalar components of the canonical form are its coefficients with respect to natural basis of the tangent space. For every frame, there exists a polynomial mapping representing the frame in a given local chart on the manifold. Therefore, for any tangent vector to the frame bundle there is a first order Taylor expansion of one-parametric family of poly­nomial mappings representing the tangent vector. We obtain the formulas of the scalar components from the equations for coefficients of the two expansions for some tangent vector.

Turbulent/non-turbulent interface (T/NTI) layer separates the turbulent and non-turbulent regions. The study of T/NTI is helpful to deepen the understanding of mass transfer between turbulent and non-turbulent regions. In this paper, the chemical reaction and scalar transport characteristics of each component in the flow field near T/NTI were studied by numerical simulation of the two-stage non-equilibrium elementary reaction (A+B→R) flow field between the jet and the environmental flow. The results show that the convection term in the reactive jet flow field dominates the influence of scalar transport in the turbulent region. At the upstream region of the jet, the chemical reaction is more intense and gradually weakens along the flow direction. There are significant chemical reactions within and near the T/NTI layer. The chemical reactions near the downstream T/NTI layer mainly occur in the turbulent core region far away from the T/NTI layer. Near the T/NTI layer, the transport mechanism of reactant A and resultant R shows a similar but opposite trend. Near the irrotational boundary of the T/NTI layer, the transport of reactant A and resultant R is mainly affected by diffusion and convection, but their concentrations hardly change with time. The transport of reactant B in the T/NTI layer is mainly affected by convection. The remaining reactant B after the chemical reaction is blocked by the flow near T/NTI to transport to the irrotational boundary.

To enhance the service life of shipping equipment and minimize surface wear, this study employs biomimetic principles, integrating fitted structures with jet dynamics to model three configurations: non-smooth structures, single jet structures, and non-smooth jet-coupled structures. We utilized the SST k-ω turbulence model for numerical simulations to investigate the drag reduction characteristics of these structural models. By varying the jet angle and speed, we analyzed the changes in viscous resistance, pressure differential resistance, and drag reduction rates at the wall surface. Furthermore, the mechanisms of compressive stress, velocity fields, vortex structures, and shear stress on drag-reducing surfaces were elucidated, revealing how these factors contribute to drag reduction in non-smooth jet-coupled structures. The results indicate that the non-smooth jet-coupled structure exhibits superior drag reduction performance at a main flow field velocity of 20 m/s. As the jet velocity increases, the viscous drag on the surface of the non-smooth jet-coupled structure decreases, while the pressure differential drag increases. Conversely, variations in the jet angle have a minimal effect on viscous drag but lead to a reduction in pressure differential drag. Specifically, when the jet velocity is set at 1 m/s, and the jet angle is 60°, the drag reduction achieved by the non-smooth jet-coupled structure peaks at 7.48%. Additionally, the non-smooth jet-coupled structure features a larger area characterized by low shear stress, along with an increased boundary layer thickness at the bottom; this configuration effectively reduces surface velocity and consequent viscous drag.

In this study, a disk-type bluff body was installed at the upper part of a nozzle exit, and the circular jet inside the nozzle was controlled using a dielectric barrier discharge (DBD) plasma actuator (DBD-PA). The effects of the changes in the excitation frequency of the jet induced by the DBD-PA on the jet diffusion were elucidated. The experiments included visualization of the jet cross-section, particle image velocimetry analysis, and velocity measurements using an I-type hot-wire anemometer. When the DBD-PA was driven at a specific burst frequency (900–1400 Hz), a lock-in phenomenon occurred, in which the frequency of vortices generated in the initial jet coincided with the burst frequency. This lock-in phenomenon suppressed the merging of vortices by generating vortices at regular intervals. When vortex merging was suppressed, the jet was less likely to be entrained into the recirculation flow generated by the bluff body, thereby increasing the downstream jet width and average flow rate.

The combined effect of cavitation and silt abrasion presents a great challenge and threat to secure the operation and the efficiency of hydraulic machineries working in sediment-laden fluid. The present paper critically reviews the current research progress on the interaction mechanisms of the bubbles and the particles. Firstly, the analytical models including boundary treatment methods for predicting the jet dynamics of the bubble collapse near particles are demonstrated. Secondly, the bubble collapsing dynamics, jet dynamics and shock wave characteristics near particles are revealed both experimentally and numerically. Finally, the bubble-particle-wall system is investigated with a focus on microjets. [ABSTRACT FROM AUTHOR]

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