Decrease In Penetration Depth Research Articles

Numerical study on enhanced-diffusion characteristics of kerosene jet in supersonic crossflow

The enhanced-diffusion characteristics of kerosene jet in supersonic crossflow under different supersonic mainstream and kerosene injection conditions were discussed in this paper. Numerous numerical simulations were conducted under varying shock wave intensities, injection momentum flux ratio conditions based on Euler-Lagrangian method. The influence of low-enthalpy (Tt=300 K) and high-enthalpy (Tt=1680 K) supersonic inflow conditions on kerosene diffusion was also involved. The results indicate that the momentum flux ratio caused by injection and evaporation jointly determines the diffusion ability of kerosene. The increase of injection momentum flux ratio and shock wave intensity promotes both the penetration ability and evaporation gain. However, the relative growth rate of penetration depth decreases, and the relative growth rate of evaporation penetration gain increases. As the jet momentum flow ratio decreases and the shock wave intensity increases, the mixing efficiency and relative growth rate of kerosene increase. A judicious design of injection measures proves to be an effective approach for enhancing the diffusion and mixing of kerosene, which holds significant importance in further enhancing the performance of supersonic combustors.

Investigation of keratolytic impact of synthetic bolalipids on skin penetration of a model hydrophilic permeant

Synthetic single-chain bolalipids (SSCBs) are novel excipients in drug delivery, with potential as stabilizers or solubilizers. However, their impact on skin barrier function has not been comprehensively studied. Therefore, two SSCBs (PC-C24-PC and PC-C32-PC) were studied in aqueous systems for their impact on penetration of a model permeant into porcine skin. Concentrations of 0.05 – 5 % w/w were tested; PC-C24-PC formulations were low-viscosity liquids while PC-C32-PC formed viscous dispersions to gels at room temperature. Formulations were compared for their ability to enhance sodium fluorescein penetration (SF, 0.1 % w/w) into skin via tape stripping. Using NIR-densitometry, the effect of SSCB formulations on corneocyte cohesion was evaluated. Data were compared with phospholipid mixture Lipoid S-75, sodium dodecyl sulfate (SDS), and polyethylene glycol 12-hydroxystearate (PEG-HS), and distilled water as negative control. Contrary to the hypothesis, both SSCBs failed to increase SF penetration into the stratum corneum, but rather showed a significant decrease in penetration depth compared to water. Both SSCBs exhibited a keratolytic effect at 5 % w/w, leading to substantial removal of proteins from the skin surface. Consequently, SSCBs may not enhance penetration of hydrophilic drugs into skin, but could be used as keratolytic agents.

Study on the spray characteristics of transverse jets with elliptical nozzles in supersonic crossflows using the volume of fluid–discrete phase model

The atomization characteristics of liquid jets injected transversely into a supersonic crossflow significantly affect the performance of scramjet engines. Existing research on this topic has mainly focused on circular nozzles, while the influence of nozzle geometry, particularly elliptical nozzles, has received relatively limited attention. Therefore, this study employs a numerical simulation method coupling the volume of fluid and discrete particle model to investigate the breakup and atomization characteristics of transverse liquid jets from elliptical nozzles with different aspect ratios under supersonic crossflow conditions, as well as the total pressure loss. The simulation model is validated against experimental data obtained from a pulse wind tunnel, including measurements of the liquid jet penetration depth and the Sauter mean diameter (SMD). The results indicate that for elliptical nozzles with an aspect ratio (AR) greater than 1, columnar breakup occurs earlier, and the columnar breakup length is shorter compared to circular nozzles. As the AR increases, the jet penetration depth decreases, while the spray expansion angle increases. Furthermore, the SMD of the atomized spray field from the circular nozzle is larger than that from the elliptical nozzles, and the SMD of the spray field is smallest for an elliptical nozzle with AR of 4. Finally, the elliptical nozzles exhibit a higher total pressure recovery coefficient, indicating reduced total pressure loss in the combustion chamber. This reduction in pressure loss is expected to improve the thrust performance of the scramjet engine.

Analysis Of The Audio-Magnetotelluric (AMT) Data Quality Using The Coherence Parameter at Malabar Mountains

Noise recorded during measurements can diminish the quality of AMT data. This can lead to decreased penetration depth and unreliable 1D inversion models. This study aimed to reduce noise and improve data quality by analyzing coherence, curve trend, and skewness. Coherence analysis was performed using robust processing and XPR editing, yielding an average coherence value of 77.5%, an improvement of 10.8% from the raw data. Noise can also alter data dimensionality; hence, skewness analysis was used to determine the effect of distortion on the impedance tensor. Results showed that the 3D dimensionality effect at 6 stations was significantly reduced following coherence and curve trend analyses.

Improving the mechanical properties of heat-treated wood bonding interphase via plasma treatment

Plasma treatment is an eco-friendly and effective way to improve the chemical reactivity of wood surface. This study explores the improvemnet of bonding properties of heat-treated wood for outdoor construction applications through plasma treatment. In this work, the low temperature atmospheric barrier discharge (DBD) plasma was used to modify the surface of heat-treated wood, and then phenol-formaldehyde (PF) resin adhesive and modified wood were applied to prepare bonded wood. The in-situ chemical structure and mechanical properties of the bonding interphase were characterized by Raman spectrum, nanoindentation and digital image correlation technology (DIC) to indicate the effect of DBD modification on the bonding properties of heat-treated wood. Results showed that after plasma treatment, the hydrophilic functional groups in the cell wall were increased and the PF adhesive molecules had chemical interaction with the cell wall. The elastic modulus (Er) and hardness (H) of wood cell wall gradually decreased along the bonding interphase towards wood with the decrease of PF penetration depth, which resulted in the reduction of the mechanical properties difference between the cell wall and PF adhesive at the bonding interphase. As a result, the shear strain was distributed homogeneously due to the effective stress transmission more at the bonding interphase. The shear strength of the control bonded wood decreased by about 35 % after heat treatment at 215 °C for 2 h, while the shear strength of heat-treated wood was increased by up to 34 % after plasma treatment.

Numerical analysis of rotating scans’ effect on surface roughness in laser-powder bed fusion

The rotating scanning strategy is a critical factor for top surface roughness in laser-powder bed fusion (L-PBF), yet the underlying mechanism remains elusive. This study introduces an integrated L-PBF model, encompassing powder packing and molten pool fluid dynamics analysis, to investigate how surface roughness accumulates across layers with non-rotating scans but is mitigated with rotating scans. To address computational complexity and prediction errors associated with multi-layer simulations, the model utilizes an experimentally built part as substrate and simulates single-layer depositions with varying scanning rotation angles. Additionally, an as-machined surface representing ideal flat substrate is included for comparative analysis. Results indicate that on as-built surfaces featuring alternating peak-valley patterns, both powder packing structure and fusion zone shape are location-dependent. To effectively characterize the packing structure on such non-flat surfaces, an effective packing density is proposed. Specifically, peak locations exhibit a thinner powder layer, a 14.5% increase in effective packing density, and a 7% decrease in penetration depth compared to valley locations. The circulation flow, driven by recoil pressure and Marangoni force, is responsible for the reduced surface roughness with rotating scans. Specifically, the circulation flow intersects with multiple peaks and valleys, effectively promoting material redistribution among these tracks and disrupting the peak-valley patterns. Conversely, the peak-valley patterns are preserved and may propagate to subsequent layers with non-rotating scans.

A solution to the problem of height overcompensation in GNSS-IR corn height measurements: a canopy reflectance calibration model

ABSTRACT The global navigation satellite system interferometric reflectometry (GNSS-IR) technique for collecting corn height has the limitation of not accounting for changes in the corn canopy reflector. A model that uses the corn canopy reflection coefficient to account for changes in the canopy’s reflector and the power attenuation of the signal reflected by the soil surface is proposed. This letter proposes a method to solve the overcompensation problem of traditional GNSS-IR vegetation height measurement. Considering the decrease in GNSS signal penetration depth and the upward shift of the actual reflecting surface caused by changes in corn leaf water content (LWC), this letter provides a calibration model for the GNSS-IR corn height measurement. The GNSS signals reflected from the corn canopy were separated using empirical mode decomposition (EMD), and the height measurement was then calibrated using the directed and reflected signal ratios. The results of the experiments show that the model proposed in this letter can effectively improve the accuracy of corn height measurement, and the root mean square error (RMSE) is reduced to 0.17 m . Compared with the current study, the model proposed in this study reduces the influence of the actual reflective surface variation of the corn canopy on the height measurement using GNSS-IR.

Simulated conformality of atomic layer deposition in lateral channels: the impact of the Knudsen number on the saturation profile characteristics.

Atomic layer deposition (ALD) is exceptionally suitable for coating complex three-dimensional structures with conformal thin films. Studies of ALD conformality in high-aspect-ratio (HAR) features typically assume free molecular flow conditions with Knudsen diffusion. However, the free molecular flow assumption might not be valid for real ALD processes. This work maps the evolution of the saturation profile characteristics in lateral high-aspect-ratio (LHAR) channels through simulations using a diffusion-reaction model for various diffusion regimes with a wide range of Knudsen numbers (106 to 10-6), from free molecular flow (Knudsen diffusion) through the transition regime to continuum flow conditions (molecular diffusion). Simulations are run for ALD reactant partial pressures spanning several orders of magnitude with the exposure time kept constant (by varying the total exposure) and with the total exposure kept constant (by varying the exposure time). In a free molecular flow, for a constant total exposure, the saturation profile characteristics are identical regardless of the LHAR channel height and the partial pressure of the reactant. Under transition regime and continuum conditions, the penetration depth decreases and the steepness of the adsorption front increases with decreasing Knudsen number. The effect of varying individual parameters on the saturation profile characteristics in some cases depends on the diffusion regime. An empirical "extended slope method" is proposed to relate the sticking coefficient to the saturation profile's characteristic slope for any Knudsen number.

Seasonal spatial-temporal variability in radar penetration depth

A fully automated processing system for measuring long-term ground deformation time series and deformation rates frame-by-frame using the Differential Interferometric Synthetic Aperture Radar (DInSAR) processing technique was developed and tested. Among the several factors that affect DInSAR’s precision, such as temporal decorrelation and atmospheric noise, it was observed that seasonal spatial-temporal variability in radar penetration depth is the greatest contributor to the loss of precision of the long-term deformation rate measurement. This spatial-temporal signal is described for a specific region in the northern US; however, it is widely observed in multiple regions. In these regions, a gradual penetration depth increase is observed in fall and winter, and an abrupt penetration depth decrease is observed in spring. The latter effect is likely caused by rapid melting of ice and snow that, at the same time, significantly reduces interferometric coherence. Within a specific geographic region, radar penetration depth spatially varies proportionally to the elevation due to an elevation-dependent temperature gradient, producing artifacts that correlate well with the topography. This signal does not extend to high-elevation regions (above ~2500 m) that do not experience seasonal thawing, which allows for distinguishing it from the topography-dependent atmospheric signals. Without accounting for the spatial-temporal variability in radar penetration depth, deformation time series in these areas can contain either an annual periodic signal with an amplitude of over 0.1 m or, if the abrupt penetration depth decrease produced by melting is not resolved due to lower coherence, an erroneous interannual trend. Spatial-temporal variability in radar penetration depth needs to be better understood and corrected to improve the precision of long-term deformation rate products, particularly in regions susceptible to seasonal freezing and thawing.

Evolution of microstructure, thermophysical and mechanical properties and wetting behavior of plasma-sprayed Yb2O3 and Y2O3 co-stabilized ZrO2 coatings during high-temperature exposure and CMAS corrosion

Doping rare-earth elements has been regarded as one of the potential ways to enhance the comprehensive performance of thermal barrier coatings. In the study, the microstructure, thermophysical and mechanical properties, and wetting behavior of Yb2O3-Y2O3 co-stabilized ZrO2 (YbYSZ) were evaluated in detail as compared with Y2O3 stabilized ZrO2 (YSZ) counterpart. During high-temperature exposure and CMAS attack at 1300 °C × 32 h, the samples did not undergo phase transformation, while samples underwent phase transformation under CMAS corrosion. In the cross-section of CMAS penetration, YbYSZ penetration depth decreases by more than 20 % compared to YSZ, and the maximum degradation depth of YSZ and YbYSZ is 27.37 μm and 11.28 μm. Additionally, the thermal conductivity of YbYSZ is lower than that of YSZ. During high-temperature exposure, the hardness and elastic modulus of YSZ show a more significant upward trend than that of YbYSZ. During CMAS corrosion, the hardness and elastic modulus offer a downward trend, with YbYSZ value higher than that of YSZ. The samples were held at 1300 °C × 180 s, the contact angle difference between YSZ (59.2°) and YbYSZ (99.9°) is the largest. The YbYSZ coating exhibits better performance on resistibility to CMAS corrosion and high-temperature exposure.

Penetration performance and failure of long rods impacting aluminum targets

A numerical study concerning the deep penetration of long steel rods into 6061-T6511 aluminum targets at high impact velocities is presented. The range of impact velocities where these rods lose their penetration capability due to their nose deformation, or impact inclination, is explored. The numerical simulations follow several complex phenomena such as the onset of rod deformation and erosion, encountered in the tests with spherical and ogive nosed rods. It turns out that penetration depth decrease of spherical nosed rods at high impact velocities, is due to their nose deformation, while ogive nosed rods are more sensitive to impact inclination. At very high impact velocities both types of rods experience significant mass erosion, and their penetration process can be described by conventional hydrodynamic penetration model for eroding rods. The numerical simulations in this work are shown to follow test results for spherical and ogive nosed rods, impacting an aluminum alloy target at a large range of impact velocities. We show that these agreements can be achieved with relatively simple constitutive relations for the steel rods and the aluminum target.

Curved grid‐scored foam core sandwich composites under low‐velocity impact loads: Effects of curvature, stacking sequence, and core finishing

AbstractThe objective of this paper is to experimentally investigate how material and geometric parameters, including face sheet layup, curvature, and core finishing, affect the contact force‐displacement behavior, absorbed energy, and damage modes of curved sandwich composites with grid‐scored foam under low‐velocity impact loads. An instrumented drop‐weight testing machine with a hemispherical impactor was used to perform low‐velocity impact tests at different energy levels. Angled‐ply stacking had the maximum contact force and impact resistance for low curvature radii. In the event of penetration, the impact energy absorption of all curved sandwich panels increased as the curvature increased. The core finishing influenced the contact forces of the curved and flat sandwich panels but not the penetration energy. The curvature and face sheet layups affected the delamination size and pattern. Angle‐ply and cross‐ply face sheets with the smallest and maximum radius of curvature, respectively, decreased penetration depth. The resin‐filled channels reduced foam cell impact damage and face‐core debonding. LVI penetration resistance was found to be highest for angle‐ply stacking and knife‐cut foam at small curvature radii. The proposed research will also provide naval designers with valuable insight into the impact response of sandwich structures used in curved parts of the hull and deck.Highlights The effect of curvature on the LVI responses varied due to face sheet layups. Core finishing affected contact forces, but not the absorbed energy. Curvature and face sheet layups affected the damage modes. Resin‐filled channels limited damage area and acted as stoppers for debonding.

Effect of material chemical composition on oxidation and stress corrosion cracking of the submerged arc welding Alloy 52M overlay in a simulated PWR primary water

Compact tension (CT) specimens from submerged arc welding Alloy 52 M overlay are used to determine the stress corrosion cracking (SCC) resistance of the dilution zones and bulk overlay metal on the 52 M side in a simulated pressurized water reactor (PWR) primary water. SEM-EDS and X-ray fluorescence spectroscopy (XRF) results show three dilution zones (DZs) on the 52 M side. Oxidation test results show that the thickness of the compact oxide layer and maximum local oxidation penetration depth decrease for 1st DZ, 2nd DZ, and bulk 52 M, which are consistent with the average SCC growth rate and the number of local intergranular SCC cracks in these regions. The dilution zones with low Cr but high Fe content possess lower oxidation and SCC resistance than the bulk 52 M.

Effectiveness of thermal radiations and homogeneous–heterogeneous reactions in Maxwell flow field across a rotating cylinder

This paper investigates the impact of cubic autocatalysis on energy transport in Maxwell fluid flow induced into a rotating cylinder inspired by a solar radiative surface. The homogeneous-reaction is assumed to be furnished by the kinetics of isothermal cubic autocatalytic and the heterogeneous reaction by kinetics of first order. To prevent induced axial secondary flow, the cylinder's rotation is maintained at a constant rate. The characteristics of thermal radiation are also investigated to regulate the pace of heat transmission. A magnetic beam is projected in the upward radial direction to control the fluid momentum. A suitable flow ansatz is used to convert the entire physical problem of thermal energy transmission and fluid flow from partial differential equations (PDEs) to nonlinear ordinary differential equations (ODEs). Results obtained numerically with the bvp4c approach are presented graphically and explained physically. It is observed that by flourishing the Reynolds parameter, the penetration depth decreases. Further, when the thermal relaxation period increases, the temperature field degrades. Moreover, when the homogeneous–heterogeneous reaction's strength is increased, a reduction in fluid concentration is shown.

Far-UVC- and UVB-induced DNA damage depending on skin type.

Far-UVC radiation sources of wavelengths 222 nm and 233 nm represent an interesting potential alternative for the antiseptic treatment of the skin due to their high skin compatibility. Nevertheless, no studies on far-UVC-induced DNA damage in different skin types have been published to date, which this study aims for. After irradiating the skin with far-UVC of the wavelengths 222 and 233 nm as well as broadband UVB, the tissue was screened for cyclobutane pyrimidine dimer-positive (CPD+ ) cells using immunohistochemistry. The epidermal DNA damage was lower in dark skin types than in fair skin types after irradiation at 233 nm. Contrary to this, irradiation at 222 nm caused no skin type-dependent differences, which can be attributed to the decreased penetration depth of radiation. UVB showed the relatively strongest differences between light and dark skin types when using a suberythemal dose of 3 mJ/cm2 . As melanin is known for its photoprotective effect, we evaluated the ratio of melanin content in the stratum basale and stratum granulosum in samples of different skin types using two-photon excited fluorescence lifetime imaging (TPE-FLIM) finding a higher ratio up to skin type IV-V. As far-UVC is known to penetrate only into the upper layers of the viable skin, the aforementioned melanin ratio could explain the less pronounced differences between skin types after irradiation with far-UVC compared to UVB.

Process Control Methods in Cold Wire Gas Metal Arc Additive Manufacturing

Cold wire gas metal arc (CWGMA) additive manufacturing (AM) is more productive and beneficial than the common electric arc processes currently used in wire arc additive manufacturing (WAAM). Adding a non-energised wire to the gas metal arc (GMA) system makes it possible to overcome a process limitation and decouple the energy input from the material feed rate. Two novel process control methods were proposed, namely, arc power and travel speed control, which can keep the required geometry accuracy in WAAM through a broad range of thermal conditions. The reinforcement area of the bead is kept constant with accurate control over the height and width while still reducing the energy input to the substrate; decreasing penetration depth, remelting, and the heat-affected zone (HAZ); and reaching a dilution lower than 10%. This work also presents improved productivity compared to all the other single-arc energy-based processes with a demonstrator part built using 9.57 kg h−1 with CWGMA AM.

Experimentally mapping the oriented-to-misoriented transition in laser powder bed fusion Ti-10%Mo alloys

Understanding the oriented-to-misoriented transition (OMT) and its origins is critical to additive manufacturing design processes. The Ti – 10 wt.% Mo alloy was printed at laser scan speeds ranging from 500 mm/s to 2500 mm/s and volumetric energy densities (VED) ranging from 50 J/mm3 to 150 J/mm3. A technique for rapidly mapping the OMT over the design space using X-ray diffraction was developed with electron backscattered diffraction verification. Mapping of the OMT revealed two independent transitions as functions of scan speed and VED respectively. Cross sections of in-situ single track scans at constant VED revealed the scan speed based OMT to be caused by a decrease in penetration depth and larger equiaxed grain zones during weld pool solidification.

Indentation size effect: an improved mechanistic model incorporating surface undulation and indenter tip irregularity

Indentation size effect (ISE), in general, is observed in shallow indentation tests, which is manifested as an increase (NISE) or decrease (RISE) in hardness with penetration depth decreases. The complicated origin of ISE is dependent on multiple factors, which can be divided into two types, both strain gradient and external factors. It's very difficult to judge which factor is the source for a certain ISE phenomenon. Further, studies on ISE phenomena under the joint of multiple factors are fewer. To date, the classical Nix-Gao model based on strain gradient has been widely recognized, but it's sometimes not suited for all ISE. And most current analytical models on ISE are not yet mature. Therefore, more mechanistic models on ISE are required, especially for RISE. Herein, we critically reviewed several mechanistic models on ISE, focusing on the exploration of RISE, and developed an analytical model incorporating external factors, i.e. surface undulation and indenter tip irregularity, to account for NISE and RISE. We examined the two external factors on the origin responsible for ISE in light of 3D numerical simulations and experimental observations, meanwhile, the combined effect of both factors on ISE was also considered. The effect of both external factors on ISE can be equivalent to a depth deviation δ. The corresponding hardness deviation caused by δ can be theoretically eliminated through correcting the depth deviation. More importantly, only after eliminating the effect of external factors on ISE, one can determine whether the ISE results from strain gradient plasticity. Finally, this paper was summarized and outlooked.

Study on spray characteristics of fan nozzle in an afterburner environment

In this study, an innovative fan nozzle was designed to improve the ignition and cross-flame performance of the integrated afterburner and the spray characteristics of the fan nozzle in an afterburner environment were studied. A laser particle analyzer and a high-speed camera were used to study the impact of pump pressure and inlet air parameters on Sauter mean diameter (SMD) distribution, penetration depth and atomization angle. The results showed that the spatial fuel distribution was a complex three-dimensional (3D) fuel field, which included three regions: upwind, core, and leeward areas. The SMD decreased as the pump pressure increased, and the SMD increased with the increase temperature. The penetration depth in the cross air was divided into internal and external penetration; the internal and external penetration depths increased firstly and then tended to be stable as the pressure. The internal and external penetration depths decreased as cross air velocity; the increase in temperature and pressure of cross air could make the internal and external penetration depth decrease. The cross air parameters and pump pressure were very important parameters. The atomization angle increased as the pump pressure and the atomization angle decreased as cross air velocity. The atomization angle decreases as the cross air temperature slightly. The results showed that fan nozzles were more suitable for ignition and cross flame in the cavity of the afterburner than the direct injection nozzles.

Study on Size Effect in Indentation Tests

The depth dependence of the indentation hardness, i.e., the indentation size effect (ISE), was manifested as an increase or decrease in hardness when penetration depth decreases, which was observed by previous experiments. Most scholars believe it is generated by strain gradient. However, additional opinions argue that other factors, similar to the strain gradient, can also contribute to the ISE. Importantly, if such an ISE occurs in an experiment, one needs to distinguish its causes. In this study, two external factors were considered, i.e., the specimen surface defect and indenter tip irregularity, which can lead to the hardness–depth-dependent relationships of the ISE. Moreover, a theoretical model was established to interpret the two dependent relationships and validated via finite element simulations. The simulation results showed that both external factors lead to significant hardness–depth dependences, in great agreement with theoretical derivations. Moreover, the simulation results demonstrated that the surface defect and indenter tip irregularity have a unified influence on the ISE, which is attributed to a sole depth deviation δ. Lastly, the ISE based on both external factors was eliminated and the real hardness was obtained. Based on this, when an ISE appears, it can be distinguished whether it is caused by external factors or strain gradient.