Types Of Jets Research Articles

Proposal of innovative arc-shaped wall-jet film cooling: A numerical investigation

Numerous methods are conceived to pick up the heat from hot plats, where, amidst all, film cooling methods possess several benefits and have always been considered. However, increasing the cooling effectiveness of this method while reducing the coolant mass flow rate has always been considered one of the concerns, and much literature has yet to be presented to surmount this problem. In this study, three different novel jet configurations including simple, semi-mushroom, and semi-oval jet types are proposed to boost the effectiveness of the film cooling method while the mass rate is drastically lower compared to the traditional jet types. Instead of using the traditional film jet that usually blows the coolant flow at a 30-90-degree angle, it can be changed so that the coolant is wholly blown in the mainstream path, simultaneously reducing the mixing ratio and increasing the diffusion of coolant film. Meantime, the arc-shaped jet design can increase the surface coverage by the coolant fluid, especially in the transverse direction. This innovative concept is also reckoned for in this study by presenting computational simulation using the k − ω − SST turbulence model, which has some superiority for turbulent near wall flows. The results showed that at BR=0.5 and x/d=5, the proposed novel jet (simple type) achieved a 17.9% improvement in averaged cooling effectiveness compared to regular jets, while utilizing a coolant mass flow rate ten times lower. Also, it found that contrary to the results related to regular jets, the averaged cooling effectiveness increases with the increment of blowing ratio in innovative proposed jet types.

A Peak-Finding Siamese Convolutional Neural Network (PF-SCNN) for Aero-Engine Hot Jet FT-IR Spectrum Classification

Aiming at solving difficulties related to aero-engine classification and identification, two telemetry Fourier transform infrared spectrometers are utilized to measure the infrared spectra of six types of aero-engine hot jets, and create a spectral data set, which is divided into a training set (80%), a validation set (10%), and a prediction set (10%). A peak-finding Siamese convolutional neural network (PF-SCNN) is used to match and classify the spectral data. During the training stage, the Siamese convolutional neural network (SCNN) is designed to extract spectral features and calculate the distance similarity. In order to improve the efficiency of the SCNN, a peak-finding method is introduced to extract the spectral peaks, which are used to train the model instead of the original spectral data. During the prediction stage, the trained model is used to calculate the similarity between the prediction set and the combined set of the training set and validation set, and the label of the most similar training data in each prediction set is used as the prediction label. The performance measures of the classification results include accuracy, precision, recall, confusion matrix, and F1-score. The experimental results show that the PF-SCNN can achieve a high classification accuracy rate of 99% and can complete the task of classifying the infrared spectra of aero-engine hot jets.

Dynamic Simulation Model and Performance Optimization of a Pressurized Pulsed Water Jet Device

Pulsed water jet technology has broad application prospects in the field of rock breaking. The pressurized pulsed water jet (PPWJ) is a new type of pulsed jet that offers high-amplitude pressurization, variable pulse pressure and frequency, and a high energy usage rate. To achieve a more destructive and powerful pulsed water jet, a dynamic simulation model of the device was established by using the AMESim software (v1400) based on the operational principle of PPWJs, and the simulation model was validated against the experimental results. The relationships between the key structural parameters of the PPWJ device and the pulse parameters were quantitatively investigated. The pulse pressure and frequency can be increased by appropriately increasing the nozzle diameter or boost ratio, and the pulse pressure will drop if the nozzle diameter or boost ratio exceeds a threshold value. Increasing the maximum displacement or action area of the piston will increase pulse length while decreasing pulse frequency; a proper match of the maximum displacement or action area of the piston will assure pulse peak pressure. The maximum outer diameter of the piston only affects the pulse frequency. The key structural parameters of the device were optimized on that foundation. Compared to the original device, the optimized device resulted in an increase in pulse frequency and jet output energy, leading to larger diameter and volume of erosion pits at the same stand-off distance and erosion time. The findings of this study offer valuable scientific insights for achieving efficient rock breaking with PPWJ.

Damage and fracture characteristics of thermal-treated granite subjected to ultra-high pressure jet

The water jet rock breaking technology has broad application prospects in geoenergy development engineering. However, the influence of reservoir temperature on the rock breaking effect is still unclear during the jet rock breaking process. To explore the mechanism of temperature on rock breaking by high-pressure water jets, experiments on the erosion of high-temperature granite by ultra-high pressure pure water jets (UHP-PWJ) and ultra-high pressure abrasive water jet (UHP-AWJ) were conducted at five rock temperatures: 25 °C, 100 °C, 200 °C, 300 °C, and 400 °C. Through three-dimensional reconstruction and microscopic observation techniques, the macroscopic and microscopic characteristics of rock fragmentation were analyzed, ultimately revealing the dynamic damage and rock breaking mechanisms of ultra-high pressure water jet. The results indicated that rock temperature influences result in different fragmentation characteristics under the action of two types of jets, with UHP-PWJ demonstrating significantly superior rock-breaking effects on high-temperature granite compared to UHP-AWJ. As granite temperature increases from 25 °C to 400 °C, the damage depth range for the UHP-PWJ is 30–75 times the nozzle diameter, while for the UHP-AWJ, it is only 30–40 times the nozzle diameter. For UHP-PWJ, the rock breaking mechanism is mainly driven by thermal stress, supplemented by high-speed jet impact. The significant increase in rock temperature significantly enhances its rock breaking effect, with erosion pits appearing in a spindle shape and more complex crack distribution around the pores. Compared with 25 °C granite, the damage caused by 400 °C granite jet impact increased by 6.8 times and the surface area of cracks increased by 6.5 times. For UHP-AWJ, high temperature hard rock fragmentation still relies mainly on jet impact and abrasive grinding. The thermal stress caused by rock temperature has a relatively small impact on its rock breaking effect, and the D value of the internal damage degree of granite at different temperatures is less than 0.005. The erosion pits are conical in shape, and no macroscopic cracks caused by jet impact and thermal cracking can be clearly observed around the pit. The research results can provide a theoretical basis for optimizing the parameters of high-pressure jet development technology for deep geoenergy.

Unravelling jet quenching criteria across L* galaxies and massive cluster ellipticals

ABSTRACT In the absence of supplementary heat, the radiative cooling of halo gas around massive galaxies (Milky Way mass and above) leads to an excess of cold gas or stars beyond observed levels. Active galactic nucleus jet-induced heating is likely essential, but the specific properties of the jets remain unclear. Our previous work concludes from simulations of a halo with $10^{14} \,\mathrm{ M}_\odot$ that a successful jet model should have an energy flux comparable to the free-fall energy flux at the cooling radius and should inflate a sufficiently wide cocoon with a long enough cooling time. In this paper, we investigate three jet modes with constant fluxes satisfying the criteria, including high-temperature thermal jets, cosmic ray (CR)-dominant jets, and widely precessing kinetic jets in $10^{12}-10^{15}\, {\rm M}_{\odot }$ haloes using high-resolution, non-cosmological magnetohydrodynamic simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model, conduction, and viscosity. We find that scaling the jet energy according to the free-fall energy at the cooling radius can successfully suppress the cooling flows and quench galaxies without violating observational constraints. On the contrary, if we scale the energy flux based on the total cooling rate within the cooling radius, strong interstellar medium cooling dominates this scaling, resulting in a jet flux exceeding what is needed. Among the three jet types, the CR-dominant jet is most effective in suppressing cooling flows across all surveyed halo masses due to enhanced CR pressure support. We confirm that the criteria for a successful jet model work across a wider range, encompassing halo masses of $10^{12}-10^{15} {\rm M_\odot }$.

Mixing effects of high-speed jets in gas-solid riser and downer reactors

For the high-temperature and short-contact time gas-solid reaction process, riser and downer are considered appropriate reactors. To realize an intensive and complete mixing of reactants with catalysts, the feed raw is always introduced in the form of high-speed jets. In this study, in order to investigate the mixing effects of different types of high-speed jets in riser and downer, traceable ozone is injected with the high-speed feed jets to react with catalyst particles. By detecting the decomposition of ozone, the gas-solid mixing and reaction in riser and downer under the influence of both co-current and counter-current injections are analyzed. The relative ozone concentration is used to reflect the location reaction extent and its radial nonuniformity index is proposed to compare the results in riser and downer. It is found that the jet influence zone in downer provides a relatively better environment for the mixing of feed jets with catalysts. In the riser, introduction of counter-current injections could improve the uniformity of gas-solid mixing in the initial contact region of feed with catalysts.

Experimental investigation of the heat transfer characteristics of a synthetic annular jet impingement on a flat surface

ABSTRACT Annular impinging jets create a more uniform flow on the impact surface compared to circular impinging jets, allowing the surface to cool better. Additionally, periodic flow oscillations significantly increase heat transfer by reducing the thermal resistance on the surface. Therefore, this study experimentally investigated the heat transfer characteristics of a synthetic annular jet impinging on a flat surface with constant heat flux. In the experiments, the jet-target surface distance (H/D), jet Reynolds number (Re j), oscillation amplitude (A o), and Womersley number (Wo) were changed. In contrast, the Prandtl number (Pr) and other geometric parameters were kept constant. The effects of these parameters on heat transfer were analyzed and the results were compared with continuous circular and annular impinging jets. Local temperature values on the target surface were obtained for different parameters and heat transfer from the surface was calculated. Experimental results showed that heat transfer increased with decreasing H/D ratio for all jet types. The highest heat transfer on the surface was achieved in synthetic jet flow. Heat transfer increased as the oscillation amplitude decreased. It was observed that there is a specific value for the Womersley number (Wo = 94) and that the heat transfer decreases after this value. For Re = 50000 and H/D = 2, the annular jet provided 27% higher heat transfer than the circular jet. In synthetic jet flow, heat transfer at H/D = 2 was improved by 21% compared to H/D = 8 for Re = 6000, A o = 1.87 and Wo = 163.

LES of the upper plenum of the liquid metal fast reactor under the forced flow conditions

A Large Eddy Simulation (LES) of the upper plenum of the E-SCAPE (European SCAled Pool Experiment) facility under the normal operations has been conducted to gain deeper insights into the thermal hydraulics phenomena in liquid metal fast reactors (LMFRs). The results unravel the overall flow features in the upper plenum, the thermal instability in the above core structure region and the impact of the jets from the barrel holes on the large flow circulation and thermal mixing.The above core structure region is represented using a homogeneous porous model. It is shown that during the normal operations, most of the hot stream of the lead bismuth eutectic (LBE) from the core center rises to the top and disperses from the upper barrel holes. Conversely, the cold LBE spread out from the lower barrel holes. Mixing between the two streams only affect the fluids leaving from the middle heights demonstrating limited mixing. These jets help to create a large circulation in the upper plenum region which prevents any thermal stratification. At the interface between the hotter and colder streams, there are unsteady large-scale structures resulting in a mixing layer in the thermal field. This strong mixing is not conventional turbulence and potentially cannot be captured by Reynolds Averaged Navier Stokes average (RANS) modelling.The flow in the upper plenum is dominated by the influences of the different types of jets, which include some free jets issued horizontally or angled upwards and some jets impinging onto the structures in the plenum. The jets overall behave similar to ‘standard’ jets, though significant interactions between the top and bottom jets and the background circulations have strong influences at later stages of the jets, typically after four jet diameters leading to the jets not reaching self-similarity. In addition, the turbulence that is observed in the upper plenum is largely generated by the jet flows and hence the distribution of turbulence is very non-uniform. Away from the jets, turbulence is minimal with the mixing largely driven by the large-scale circulation.

The Cause of the Difference in the Propagation Distances between Compact and Transient Jets in Black Hole X-Ray Binaries

Accreting black hole binaries change their properties during evolution, passing through two main luminous states, dominated by either hard or soft X-rays. In the hard state, steady compact jets emitting multiwavelength radiation are present. Those jets are usually observed in radio, and when resolved, their extent is ≲1015 cm. Then, during hard-to-soft transitions, powerful ejecta in the form of blobs appear. They are observed up to distances of ∼1018 cm, which are ≳1000 times larger than the extent of hard-state jets. On the other hand, estimates of the accretion rates during most luminous hard states and the hard-to-soft transitions are very similar, implying that maximum achievable powers of both types of jets are similar and cannot cause a huge difference in their propagation. Instead, we explain the difference in the propagation length by postulating that the ejecta consist of electron-ion plasmas, whereas the hard-state jets consist mostly of electron–positron pairs. The inertia of the ejecta are then much higher than those of compact jets, and the former are not readily stopped by ambient media. A related result is that the accretion flow during the hard state is of standard and normal evolution, while it is a magnetically arrested disk during transient ejections. The pairs in hard-state jets can be produced by collisions of photons of the hard spectrum emitted by hot accretion flows within the jet base. On the other hand, the X-ray spectra during the state transitions are relatively soft, and the same process produces much fewer pairs.

Research on the destroy characteristics of PTFE/Cu composite liner to explosive reactive armor

The jet generated through PTFE based inert material liner has the characteristics of low energy, low density, and large aspect ratio, which can effectively achieve the “penetration without explosion” of explosive reactive armor. PTFE/Cu composite material liner with various densities is prepared, to research the roles of preparation procedure and density in the destroy effect of jet on reactive armor. Through numerical simulation research, it was found that there was no reaction at all in the explosive layer penetrated by the jet generated by the sinter liner molded, while the explosive layer penetrated by the jet generated through the hot-pressing sintering and extrusion molding liner experienced local reactions on the jet impact channel, and the overall explosive layer did not undergo any reaction. Through experimental verification, it has been proven that all three types of jets have achieved “penetration without explosion” on explosive reactive armor.

High-speed ultrasound imaging of bubbly flows and shear waves in soft matter.

In this methods paper, we explore the capabilities of high-speed ultrasound imaging (USI) to study fast varying and complex multi-phase structures in liquids and soft materials. Specifically, we assess the advantages and the limitations of this imaging technique through three distinct experiments involving rapid dynamics: the underwater flow induced by an external jet, the dissolution of sub-micron bubbles in water, and the propagation of shear waves in a soft elastic material. The phenomena were simultaneously characterized using optical microscopy and USI. In water, we use compounded USI for tracking a multi-phase flow produced by a jetting bubble diving into a liquid pool at speeds around 20 m s-1. These types of jets are produced by focusing a single laser pulse below the liquid surface. Upon breakup, they create a bubbly flow that exhibits high reflectivity to the ultrasound signal, enabling the visualization of the subsequent turbulent flow. In a second experiment, we demonstrate the potential of USI for recording the diffusive shrinkage of micro- and nanobubbles in water that could not be optically resolved. Puncturing an elastic material with a liquid jet creates shear waves that can be utilized for elastography measurements. We analysed the shape and speed of shear waves produced by different types of jetting bubbles in industrial gelatin. The wave characteristics were simultaneously determined by implementing particle velocimetry in optical and ultrasound measurements. For the latter, we employed a novel method to create homogeneously distributed micro- and nanobubbles in gelatin by illuminating it with a collimated laser beam.

A neural network potential energy surface assisted molecular dynamics study on the pyrolysis behavior of two spiro-hydrocarbons.

Spiro-hydrocarbons are potentially a type of novel alternative jet fuel due to their high density and net heat of combustion. In this work, the pyrolysis study of two spiro-hydrocarbons (spiro[cyclopropane-1,6'-tricyclo[3.2.1.02,4]octane] (C10H14) as Fuel 1 and spiro[bicyclo[2.2.1]heptane-2,1'-cyclopropane] (C9H14) as Fuel 2) is performed via molecular dynamics (MD) simulations, with a neural network potential energy surface (NNPES), deep potential (DP) model, adopted. The data set for the DP model of each fuel is constructed after 31 and 27 iterations, respectively. The high precision of the DP model is demonstrated, and the temperature transferability of each model is observed. The overall pyrolysis performance is evaluated with the fuel decomposition rate, showing that both fuels have comparable gas-reactivity to commercial aviation fuels, such as JP-10. The reaction networks of initial pyrolysis for Fuels 1 and 2 are constructed, and the contribution of each pathway is discussed. Fuel 1 tends to form an unsaturated six-membered ring structure, while Fuel 2 generates unsaturated open-chain hydrocarbons. Further analyses of the MD results provide time-evolution information on each component in the pyrolysis species pool. Compared to Fuel 1, the initial pyrolysis of Fuel 2 leads to more hydrogen, alkenes, and alkanes, as well as fewer monocyclic aromatic hydrocarbons (MAHs), demonstrating a reduced tendency for afterward coking. This work might contribute to the development of the mechanism of the two spiro-hydrocarbons and guide the research of other similar structural fuels.

The spatial density distribution of H2O2 in the effluent of the COST-Jet and the kINPen-sci operated with a humidified helium feed gas

Abstract Cold atmospheric plasma jets operated with a helium feed gas containing small admixtures of water vapour are excellent sources of H2O2 for direct biomedical applications. However, H2O2 is typically distributed non-uniformly throughout the effluent region, meaning the dosage received by a patient or substrate is dependent on their positioning relative to the plasma source. This study presents the spatial distribution of absolute H2O2 number densities in the effluent of two popular plasma jets, the COST-Jet and the kINPen-sci plasma jet, when operated with a humidified helium feed gas. The measurements were performed using continuous wave cavity ring-down spectroscopy with a tunable, mid-infrared laser. The H2O2 number density measured close to the jet nozzle is 2.3 × 1014 cm−3 for the kINPen-sci plasma jet and 1.4 × 1014 cm−3 for the COST-Jet. The average number density of H2O2 in the effluent of the kINPen-sci plasma jet is a factor of two higher than in the effluent of the COST-Jet. The distribution of H2O2 in the COST-Jet effluent is initially highly uniform and suggests negligible mixing of H2O2 with the ambient air up to 15 mm from the jet nozzle, although it is rapidly diluted at further distances. In the case of the kINPen-sci plasma jet, the number density of H2O2 has a more pronounced radial distribution close to the nozzle, while the mixing with the ambient air is more gradual at further distances from the nozzle. It is evident that a detailed understanding of the H2O2 production in the plasma source, as well as of the transport of H2O2 to the substrate through the effluent, is required in order to optimise the intended effects. This work serves to highlight the difference of the distinct spatial distribution of H2O2 in the effluent of both types of plasma jets when considering their direct application in biomedicine.

The hydrodynamics of jet propulsion swimming in hatchling and juvenile European common cuttlefish, Sepia officinalis.

Cuttlefish swim using jet propulsion, taking a small volume of fluid into the mantle cavity before it is expelled through the siphon to generate thrust. Jet propulsion swimming has been shown to be more metabolically expensive than undulatory swimming, which has been suggested to be due to the lower efficiency of jet propulsion. The whole-cycle propulsive efficiency of cephalopod molluscs ranges from 38 to 76%, indicating that in some instances jet propulsion can be relatively efficient. Here, we determined the hydrodynamics of hatchling and juvenile cuttlefish during jet propulsion swimming to understand the characteristics of their jets, and whether their whole-cycle propulsive efficiency changes during development. Cuttlefish were found to utilise two jet types: isolated jet vortices (termed jet mode I) and elongated jets (leading edge vortex ring followed by a trailing jet; termed jet mode II). The use of these jet modes differed between the age classes, with newly hatched animals nearly exclusively utilising mode I jets, while juveniles showed no strong preferences. Whole-cycle propulsive efficiency was found to be high, ranging from 72 to 80%, and did not differ between age classes. During development, Strouhal number decreased as Reynolds number increased, which is consistent with animals adjusting their jetting behaviour in order to maximise whole-cycle propulsive efficiency and locomotor performance. Although jet propulsion swimming can have a relatively high energetic cost, in cuttlefish and nautilus, both neutrally buoyant species, the whole-cycle propulsive efficiency is actually relatively high.

Optimization of Oxygen Injection Conditions with Different Molten Steel Levels in the EAF Refining Process by CFD Simulation

In electric arc furnace (EAF) steelmaking, oxygen jets play a crucial role in controlling stirring ability, chemical reactions, and energy consumption. During the EAF lifetime, refractory wear leads to a decrease in the molten steel level and an increase in the nozzle-to-steel distance, thereby negatively affecting the overall energy efficiency of the process. The objective of this study is to optimize the energy efficiency of the EAF refining process by adjusting the nozzle flow conditions and conducting an analysis of jet performance using computational fluid dynamics (CFD) simulation. Three types of injection jets were considered: the conventional jet, the CH4 coherent jet, and the CH4 + O2 coherent jet. The findings reveal that the shrouded flame of the coherent jet enhances jet performance by maintaining the maximum velocity, extending the potential core length, and increasing the penetration depth in the molten steel bath. To maintain the jet performance in response to an increased nozzle-to-steel distance resulting from refractory wear, transitions from the conventional jet to the CH4 coherent jet and the CH4 + O2 coherent jet are recommended once the nozzle-to-steel distance increases from its initial level of 1000 mm to 1500 mm and 2000 mm, respectively.

Jets and Mirror Mode Waves in Earth's Magnetosheath.

Magnetosheath jets are localized plasma structures with high dynamic pressure which are frequently observed downstream of the Earth's bow shock. In this work we analyze Magnetospheric MultiScale magnetic field and plasma data and show that jets can be found in the quasi-perpendicular magnetosheath in regions permeated by Mirror mode waves (MMWs). We show that structures identified as jets by their enhanced dynamic pressure can have very different internal structure, with variable signatures in magnetic field magnitude and components, velocity, and density and can be associated to ion distribution functions of various types. This suggests that jets observed in the quasi-perpendicular magnetosheath are generated by different mechanisms. We find that jets can be related to traveling foreshocks, flux transfer events, and some have MMWs inside them. Our results suggest that some jets have a local source and their formation does not depend on upstream structures. We find that different types of ion distributions can exist inside the jets, while in some cases anisotropic distributions are present, in others counterstreaming distributions exist. We also show that for jets with MMWs inside them, ion distributions can be modulated. This highlights the importance of using ion distributions to identify and classify different types of jets.

Redesigning TBM-1.7 Combustion Unit to Expand the Temperature Range

It is shown that the transition to a new low-temperature method of convective drying leads to a reduction in grain drying costs.The implementation of this method is confirmed to require expanded temperatures generated by the TBM-1.7 furnace unit that the SZSh-16A shaft dryer is equipped with. It is noted that a plant-manufactured burner nozzle works smoothly only when the fuel consumption is 40-100 kilograms per hour, and the air heating temperatures are 50-130 degrees Celsius. (Research purpose) To determine the jet optimal parameters for smooth operation of the nozzle in the TBM-1.7 combustion unit working on the liquid fuel at the extended air heating temperatures of 15-130 degrees Celsius. (Materials and methods) The designs of four types of jets were studied on the burner nozzle of the TBM-1.7 combustion unit. In total, the operation of 160 jets was examined. The jets were made of steel. They differed in the number of holes, their length, diameter, the availability of threads. (Results and discussion) It is determined that the nozzle smooth operation is provided only by jets with threaded holes, whose optimal length is 4 millimeters. The air heating temperature of 15-25 degrees Celsius is provided by M3 four-hole jet, and the temperature of 25-40 degrees Celsius is provided by M4 three-hole jet. (Conclusions) It is found that jets with smooth holes, regardless of their types, do not provide fuel combustion. It is found that the transition to a new low-temperature convective method led to a reduction in fuel consumption during the drying process, which, in turn, made it possible to save 300 thousand rubles during the harvesting period on the experimental farm in 2022.

Study on the liquid jet and shock wave produced by a near-wall cavitation bubble containing a small amount of non-condensable gas

The liquid jet and shock wave produced by a near-wall cavitation bubble are two major reasons resulting in material-wall damage. To better understand the destructive mechanism, the complete process of action of the multi-cycle cavitation bubble collapsing on the nearby wall with the effect of non-condensable gas under different stand-off distances was numerically investigated. For this purpose, a fully compressible solver is further developed with the implementation of a modified phase-change model. Validations were conducted by comparing the numerical results with the experimental data. Furthermore, the high-pressure zones on the wall induced by the shock wave and liquid jet are carefully analyzed. Numerical results reveal that the bubble behavior, shock wave propagation, and liquid jet types are highly associated with the stand-off distance. Finally, the potential material-wall damage is estimated by using the pressure impulse, and the relationship between the pressure impulse at the central point and the stand-off distance is quantitatively analyzed. It is found two pressure impulse peaks are at the central point.

Correlation of plasma generated long-lived reactive species in aqueous and gas phases with different feeding gases

Reactive species are believed to play an important role in the treatment effects in both direct and indirect plasma applications. To better understand plasma chemistry and reveal the reactive species generated in the aqueous and gas phases, this study investigated the reactive species (i.e. H2O2, and ) that were generated using two types of plasma jets with different feeding gases (i.e. air, CO2, and N2) and treatment time (i.e. 0, 5, 10 and 20 min) in both aqueous and gas phases. Under the same treatment conditions, the determinations of reactive species in ambient air (X-variable) were carried out using optical absorption spectroscopy (OAS), and the detection of reactive species in plasma-activated water (PAW, Y-variable) was using wet chemical-based colourimetric methods. For both measurements, OAS spectral features and the contents of reactive species in PAW varied from different feeding gases and treatment times. The correlations of X and Y were developed using partial least squares (PLS) regression modelling. High collinearity (R2CVs ∼ 0.955–1) was shown between the independent X and Y. Based on the PLS regression results, the selectivity ratio (SR) algorithm was used to select the most important spectral wavelengths that are highly related to the functional groups of these reactive species.

Experimental verification of two types of gluon jets in QCD

The Abelian decomposition of QCD tells that there are two types of gluons, the color neutral neurons and colored chromons. We propose to confirm the Abelian decomposition testing the existence of two types of gluon jets experimentally. We predict that one quarter of the gluon jet is made of the neurons which has the color factor $3/4$ and the sharpest jet radius and smallest charged particle multiplicity, while the three quarters of the gluon jet are made of the chromons with the color factor $9/4$, which have the broadest jet radius (broader than the quark jet). Moreover, we argue that the neuron jet has a distinct color flow which forms an ideal color dipole, while the quark and chromon jets have distorted dipole pattern. To test the plausibility of this proposal, we suggest to analyze the gluon distribution against the jet shape (the sphericity) and/or particle multiplicity from the existing gluon jet events and look for two distinct peaks in the distribution.