Decrease In Penetration Depth Research Articles

Parametric effect on the mixing of the combination of a hydrogen porthole with an air porthole in transverse gaseous injection flow fields

The dual transverse injection system with a front hydrogen porthole and a rear air porthole arranged in tandem is proposed, and this is a realistic approach for mixing enhancement and penetration improvement of transverse injection in a scramjet combustor. The influence of this dual transverse injection system on mixing characteristics has been evaluated numerically based on grid independency analysis and code validation. The numerical approach employed in the current study has been validated against the available experimental data in the open literature, and the predicted wall static pressure distributions show reasonable agreement with the experimental data for the cases with different jet-to-crossflow pressure ratios. The obtained results predicted by the three-dimensional Reynolds-average Navier – Stokes (RANS) equations coupled with the two equation k-ω shear stress transport (SST) turbulence model show that the air pothole has an great impact on penetration depth and mixing efficiency, and the effect of air jet on flow field varies with different values of the aspect ratio. The air porthole with larger aspect ratio can increase the fuel penetration depth. However, when the aspect ratio is relatively small, the fuel penetration depth decreases, and even smaller than that of the single injection system. At the same time, the air pothole has a highly remarkable improvement on mixing efficiency, especially in the near field. The smaller the aspect ratio of the air porthole is, the higher the mixing efficiency in the near field is. This is due to its larger circulation in the near field. The dual injection system owns more losses of stagnation pressure than the single injection system.

The nonlinear effect of alkyl chain length in the membrane interactions of phenolipids: Evidence by X‐ray diffraction analysis

Despite the evidence supporting a relationship between phenolipid's alkyl chain length and their interaction/affinity with membranes, such a connection has not been directly evaluated. In this study, the membrane interactions of rosmarinic acid, and its corresponding alkyl esters having 4 carbon (RC4), 8 carbon (RC8), 10 carbon (RC10), and 16 carbon (RC16) have been investigated via small angle X‐ray scattering (SAXS) approaches in model membrane liposomes. The results of this work show significant differences between the tested phenolipids with respect to their interaction and location within the lipid bilayer. Both membrane affinity and penetration depth follow a nonlinear behavior. They have been shown to increase as a function of increasing alkyl chain length until a threshold is reached for medium alkyl chain, beyond which any lengthening of the chain results in a collapse. RC8 show the highest affinity for the membrane, whereas RC10 constitute a critical chain length from which the penetration depth decreases. The X‐ray scattering analyses seem to perfectly correlate with the phenolipids’ activities (antioxidant and membranes crossing) previously observed both in biological system and in formulated lipid dispersions.Practical applications: Phenolic compounds are potent antioxidants that may play an important role as well in biological system as in formulated lipid dispersions. However, their activity is often limited by low solubility or bioavailability. Lipophilization of phenolic compounds may increase their solubility in lipophilic matrices, conferring better antioxidant protection for food or nonfood application. In biological system, lipophilization may contribute to easier penetration of antioxidants through lipid bilayer of cell membranes, which can significantly increase their bioavailability. Despite the evidence supporting a relationship between phenolipid's alkyl chain length and their interaction/affinity with membranes, such a relationship has not been directly evaluated. Investigation of membrane interactions between phenolic and its lipophilic derivative, via SAXS approaches in model membrane liposomes, provide new knowledge about this class of compound with the perspective to be used as substances with maintained or improved biological properties for food, cosmetic and pharmaceutical applications.An X‐ray diffraction analysis highlighted different membrane affinity and nonlinear penetration depth of a series of phenolipids (rosmarinic acid, and its corresponding alkyl esters having 4 carbon (RC4), 8 carbon (RC8), 10 carbon (RC10), and 16 carbon (RC16)). The results seem to perfectly correlate with the phenolipids’ activities (antioxidant and membranes crossing) previously observed both in biological system and in formulated lipid dispersions.

A novel process and its mechanism for recovering alumina from diasporic bauxite

A novel process involving microwave roasting of slurry mixtures of diasporic bauxite and alkaline solutions followed by dilute alkaline leaching, is proposed for extracting alumina from low grade diasporic bauxite ores. It was found that when the mole ratio of mNaOH/(mAl+mFe) and mCa/mSi in the slurry mixture was close to 1 and 2, the Al and Si contained in the bauxite were completely liberated into soluble NaAlO2 and insoluble CaSiO4 after roasting using a 1.0kW microwave source at 800°C for 20min. The roasting process significantly improved the performance of the downstream leaching processing. The extraction of Al reached 97% while that of Si was as low as 7%, on leaching in low-concentration alkali solution at 80°C under atmospheric pressure for 20min. A new mechanism involving flashing, layering and homogeneous reaction is proposed for the new microwave roasting process. The key steps proposed are: creation of a hot core at the peak location of the electric field, preheating of the outer layer facilitated by heat conduction and vapor from the hot core, and finally microwave heating of the outer layer due to increasing dielectric loss and decreasing penetration depth.

Improvement of the Early-Age Compressive Strength, Water Permeability, and Sulfuric Acid Resistance of Scoria-Based Mortars/Concrete Using Limestone Filler

Natural pozzolan is being widely used as cement replacement. Despite the economic, ecological, and technical benefits of its adding, it is often associated with shortcomings such as the need of moist-curing for longer time and a lower early strength. This study is an attempt to investigate the effect of adding limestone filler on the compressive strength and durability of mortars/concrete containing scoria. Sixteen types of binders with different replacement levels of scoria (0, 10, 20, and 30%) and limestone (0, 5, 10, and 15%) were prepared. The development of the compressive strength of mortar/concrete specimens was investigated after 2, 7, 28, and 90 days’ curing. In addition, the acid resistance of the 28 days’ cured mortars was evaluated after 90 days’ exposure to 5% H2SO4. Concrete permeability was also evaluated after 2, 7, 28, and 90 days’ curing. Test results revealed that there was an increase in the early-age compressive strength and a decrease in water penetration depths with adding limestone filler. Contrary to expectation, the best acid resistance to 5% H2SO4 solution was noted in the mortars containing 15% limestone. Based on the results obtained, an empirical equation was derived to predict the compressive strength of mortars.

Comparison of penetration performance and penetration mechanism of w-cu shaped charge liner against three kinds of target: Pure copper, carbon steel and Ti-6Al-4V alloy

In order to investigate the interaction between shaped charge jet and target, three different targets, including pure copper target, carbon steel target and Ti-6Al-4V alloy target, were penetrated by W-Cu shaped charge jet. Penetration performance and corresponding penetration mechanisms were studied. Calculated theoretical penetration depth ratio of Ti-6Al-4V alloy target, pure Cu target and carbon steel target is 10:2.8:5.7, while the practical penetration depth ratio is 10:28:21, indicating that the interaction between jet and target has a significant effect on the penetration depth. Microstructural analysis shows that the interaction between jet and Cu target is the lightest among the three kinds of targets, leading to an increased penetration depth of Cu target. The interaction between jet and Ti-6Al-4V alloy target is the severest, resulting in an increased transverse energy dissipation of jet and decreased penetration depth of Ti-6Al-4V alloy target. Given the significant interaction between jet and target, we propose a modified equation of penetration depth by adding an empirical parameter, which provides a platform to predict more accurate penetration depth.

Detection Limits for Blood on Fabrics Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy and Derivative Processing.

Attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) was used to detect blood stains based on signature protein absorption in the mid-IR region, where intensity changes in the spectrum can be related to blood concentration. Partial least squares regression (PLSR) was applied for multivariate calibrations of IR spectra of blood dilutions on four types of fabric (acrylic, nylon, polyester, and cotton). Gap derivatives (GDs) were applied as a preprocessing technique to optimize the performance of calibration models. We report a much improved IR detection limit (DL) for blood on cotton (2700× in dilution factor units) and the first IR DL reported for blood on nylon (250×). Due to sample heterogeneity caused by fabric hydrophobicity, acrylic fabric produced variable ATR FT-IR spectra that caused poor DLs in concentration units compared to previous work. Polyester showed a similar problem at low blood concentrations that lead to a relatively poor DL as well. However, the increased surface sensitivity and decreased penetration depth of ATR FT-IR make it an excellent choice for detection of small quantities of blood on the front surface of all fabrics tested (0.0010 µg for cotton, 0.0077 µg for nylon, 0.011 µg for acrylic, and 0.0066 µg for polyester).

Unusual pressure evolution of the Meissner and Josephson effects in the heavy-fermion superconductorUPt3

The Josephson effect between a single-crystal ${\mathrm{UPt}}_{3}$ and a conventional superconductor Al has been investigated under pressure for the junction on the ${\mathrm{UPt}}_{3}$ surface perpendicular to the hexagonal $c[0001]$ axis. Simultaneously measured magnetization has revealed that the Meissner fraction approaches a minimum value of $\ensuremath{\sim}1%$ at the critical pressure of ${P}_{\mathrm{c}}\ensuremath{\sim}0.4\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$. The critical temperature ${T}_{\mathrm{c}}$ and the temperature ${T}_{\mathrm{J}}$ where a measurable Josephson critical current ${I}_{\mathrm{c}}$ first appears decrease with increasing pressure; the decreasing rate of $|d{T}_{\mathrm{c}}/dP|$ is almost constant, whereas $|d{T}_{\mathrm{J}}/dP|$ shows an abrupt increase above ${P}_{\mathrm{c}}$, indicating that the Josephson effect is suppressed above ${P}_{\mathrm{c}}$. These results, together with the decrease in penetration depth $\ensuremath{\lambda}$ derived from the magnetic-field dependence of ${I}_{\mathrm{c}}$, suggest that the superconducting phase is modified above ${P}_{\mathrm{c}}$ by the disappearance of the symmetry-breaking antiferromagnetic order.

Nonextensive statistics and skin depth of transverse wave in collisional plasma

Skin depth of transverse wave in a collisional plasma is studied taking into account the nonextensive electron distribution function. Considering the kinetic theory for charge particles and using the Bhatnagar-Gross-Krook collision model, a generalized transverse dielectric permittivity is obtained. The transverse dispersion relation in different frequency ranges is investigated. Obtaining the imaginary part of the wave vector from the dispersion relation, the skin depth for these frequency ranges is also achieved. Profiles of the skin depth show that by increasing the q parameter, the penetration depth decreases. In addition, the skin depth increases by increasing the electron temperature. Finally, it is found that in the high frequency range and high electron temperature, the penetration depth decreases by increasing the collision frequency. In contrast, by increasing the collision frequency in a highly collisional frequency range, the skin depth of transverse wave increases.

Evidence for ferromagnetic coupling at the doped topological insulator/ferrimagnetic insulator interface

One of the major obstacles of the magnetic topological insulators (TIs) impeding their practical use is the low Curie temperature (Tc). Very recently, we have demonstrated the enhancement of the magnetic ordering in Cr-doped Bi2Se3 by means of proximity to the high-Tc ferrimagnetic insulator (FMI) Y3Fe5O12 and found a large and rapidly decreasing penetration depth of the proximity effect, suggestive of a different carrier propagation process near the TI surface. Here we further present a study of the interfacial magnetic interaction of this TI/FMI heterostrucutre. The synchrotron-based X-ray magnetic circular dichroism (XMCD) technique was used to probe the nature of the exchange coupling of the Bi2−xCrxSe3/Y3Fe5O12 interface. We found that the Bi2−xCrxSe3 grown on Y3Fe5O12(111) predominately contains Cr3+ cations, and the spin direction of the Cr3+ is aligned parallel to that of tetrahedral Fe3+ of the YIG, revealing a ferromagnetic exchange coupling between the Bi2−xCrxSe3 and the Y3Fe5O12.

Dielectric properties and model food application of tylose water pastes during microwave thawing and heating

The dielectric properties of tylose water pastes during microwave thawing and heating were measured over 300–3000 MHz and −30 to +60 °C, and the feasibility of their use as a frozen model food instead of frozen lean tuna was evaluated. The effects of salt (NaCl) content (0.5–2.0%, wb) on the dielectric properties were investigated. Although salt is a good additive for increasing the dielectric loss factor, higher salt addition increased the thawing time and non-uniformity through decreased penetration depth. A similar response to increasing temperature between frozen lean tuna and tylose paste was observed during MW thawing and heating at 2450 MHz, due to similarities in penetration depth. This was possible by an appropriate adjustment of the dielectric properties of tylose by salt addition (0.5% NaCl). This study confirmed the potential of frozen tylose paste as a model food in evaluating performance of microwave thawing of real foods.

Evaluation of Stain Penetration by Beverages in Demineralized Enamel Treated With Resin Infiltration.

To evaluate stain penetration by different beverages in artificially demineralized human teeth treated with resin infiltration. Sixty extracted human permanent molars were demineralized, treated with resin infiltration (Icon), and immersed in four different beverages (coffee, grape juice, iced tea, and distilled water; N=15) for four weeks. After aging, teeth in the distilled water group were stained with 2% methylene blue for 24 hours. All teeth were sectioned, and stain penetration was evaluated under light microscopy. Chi-square test, independent and paired sample t-test, analysis of variance with the Fisher least significant difference post hoc test, and the Kruskal-Wallis test were used to analyze the results (p<0.05). Resin infiltration-treated surfaces (Icon surfaces) had statistically significant fewer samples with presence of stain penetration compared to untreated surfaces (control surfaces) (p<0.001). There was also a significant decrease in depth of stain penetration in Icon surfaces compared to the control surfaces (p<0.001). Among tested beverage groups, iced tea showed significantly greater depth of stain penetration (0.134±0.029 mm), followed by grape juice (0.118±0.047 mm), methylene blue (0.022±0.019 mm), and coffee (0.008±0.017 mm; p<0.001). Both Icon and control surfaces exhibit stain penetration by different beverages (iced tea, grape juice, and coffee). However, resin-infiltrated enamel surfaces allow significantly less depth of stain penetration compared to untreated surfaces. The iced tea group presents greatest depth of stain penetration, followed by grape juice, methylene blue, and coffee.

Effect of Thermal Frequency on AA6061 Aluminum Alloy Double Pulsed Gas Metal Arc Welding

The present investigation aims to contrast the effect of the commonly used thermal frequency on welding process suitability, weld profile, weld macrostructure, and weld hardness on AA6061 aluminum alloy double pulsed gas metal arc welding. Material manufacturing processes and welding parameters with thermal frequencies of 2, 3, and 4 Hz are described in detail. Three defect-free welds were successfully formed at these thermal frequencies. The results indicate the following: (1) thermal frequency has no effect on welding process suitability when the welding parameters are self-matching; and (2) at increased thermal frequency, weld ripple distance reduces, maximum penetration depth decreases, grain size of the fusion zone decreases, and fusion zone hardness increases.

Influence of Drift Velocity and Distance Between Jet Particles on the Penetration Depth of Shaped Charges

AbstractThe penetration depth of shaped charge jet into target is strongly affected by the stand‐off. The penetration process terminates even when the jet velocity is still high, and the penetration capability of jet particles degrades after jet breakup at a large stand‐off. This work presents an analytical model to describe the radial drift velocity and distance between jet particles, which leads to decreased penetration depth. The results show that jet particles with low drift velocity impact the crater wall easily. Furthermore, the jet particles cannot reach the crater bottom to increase depth because the crater diameter generated by the jet is quite small. Moreover, the distances between jet particles also play an important role in penetration depth under the influences of strain hardening of target, as well as tumbling and dispersion of jet particles. The radial drift velocity and distance between jet particles are investigated by applying the model to non‐precision charge and precision charge penetrations into target at different stand‐offs. The cutoff jet velocity and cutoff penetration velocity also are determined based on the analytical model. With increased stand‐off, the cutoff jet velocity increases, and the cutoff penetration velocity is almost constant. This result is proven by a number of experiments. The stand‐off curves of two charges are also calculated, and results are in good agreement with experiments. The stand‐off curve can be determined with only two or three experiments using the proposed method. Notably, jet particles should have a slow drift velocity and great penetration capability after breakup for suitable shaped charge.

Penetration resistance of armor ceramics: Dimensional analysis and property correlations

A new dimensionless relationship for analysis of ballistic penetration data is derived and applied to polycrystalline ceramic materials. Targets consist of ceramic tiles backed by thick metallic plates within which residual penetration depths have been reported in experimental studies. Particular ceramics analyzed here are low- and high-purity alumina, aluminum nitride, boron carbide, silicon carbide, and titanium diboride. Data for penetration depth versus ceramic tile thickness tend to fall on lines of constant slope regardless of impact velocity, suggesting effects of penetrator velocity and tile thickness may be represented by a separable function of rank two for normalized depth of penetration. The particular relationship developed here contains two material parameters: a length scale and an energy per unit mass. Simultaneous consideration of results of the dimensional analysis and material properties suggest that the length scale, which is related to decreasing penetration depth with increasing tile thickness, correlates with the ratio of surface energy to elastic modulus. The energy per unit mass, which is linked to the relationship between penetration depth and penetrator velocity, correlates with dynamic shear strength of failed ceramic reported from plate impact experiments, divided by mass density. The dimensional analysis provides a structured framework under which future multiscale simulations and validation experiments can be organized and compared.

Acoustic phonon behavior of PbWO4 and BaWO4 probed by low temperature Brillouin spectroscopy

Temperature dependent acoustic phonon behavior of PbWO4 and BaWO4 using Brillouin spectroscopy has been explained for the first time. Low temperature Brillouin studies on PbWO4 and BaWO4 have been carried out from 320–20K. In PbWO4, we observe a change in acoustic phonon mode behavior around 180K. But in the case of BaWO4, we have observed two types of change in acoustic phonon mode behavior at 240K and 130K. The change in Brillouin shift ω and the slope dω/dT are the order parameter for all kinds of phase transitions. Since we do not see hysteresis on acoustic phonon mode behavior in the reverse temperature experiments, these second order phase transitions are not related to structural phase change and could be related to acoustic phonon coupled electronic transitions. In PbWO4, the temperature driven phase transition at 180K could be due to changes in the environment around the lead vacancy (VPb2−) changes the electronic states. In the case of BaWO4, the phase transition at 240K shows the decrease in penetration depth of WO3 impurity. So it becomes more metallic. The transition at 130K could be the same electronic transitions as that of PbWO4 as function of temperature. The sound velocity and elastic moduli of BaWO4 shows that it could be the prominent material for acousto-optic device applications.

Influence of laser-induced plume on penetration in laser welding

The influence of a laser-induced plume on penetration is discussed in remote laser welding. Melt-runs accompanying plumes of various lengths were carried out in order to investigate the influence of plume on penetration using a 4.5 kW YAG laser and air knife. Penetration depth obviously reduced in conditions with a long plume. It is considered that the decrease of penetration depth comes from attenuation of laser power in the plume, through the decrease in weld metal cross-sectional area. Attenuation of laser power was estimated at about 7% and focus shift was estimated to be about 0.7 mm in the experimental conditions with a plume of 90-mm length, compared with the conditions with a plume of 11-mm length.

Dissociation of methane and nitrogen molecules and global transport of tracer impurities in an ASDEX Upgrade L-mode plasma

We model the dissociation of injected methane (13CH4) and nitrogen (15N2) molecules and the subsequent transport of tracer ions in ASDEX Upgrade (AUG) low confinement (L-mode) plasma conditions resembling a tracer injection experiment conducted in 2011. Based on simulations with the ERO code, the dissociation is predicted to occur relatively close to the injection port in the far-scrape-off layer (far-SOL) plasma with the dissociation location moving closer to the injection location with increasing plasma density and heating power. Simulations of global transport of the tracer ions resulting from the dissociation using the ASCOT code predict that the decreasing penetration depth of the molecules (dissociation in the far-SOL) increases the ratio between main chamber and divertor deposition.

Depth dependent strain rate sensitivity and inverse indentation size effect of hardness in body-centered cubic nanocrystalline metals

Size effects on hardness (H) and strain rate sensitivity (m) of nanocrystalline (NC) body-centered cubic Mo thin film were examined under nanoindentation testing. Contrast to existing reports that there was no indentation size effect on hardness in NC metals, inverse indentation size effect (ISE) in NC Mo was observed for the first time at penetration depths ranging from 15 to 200nm, at all the loading strain rates applied. In addition, the strain rate sensitivity of NC Mo exhibited strong dependence on penetration depth, increasing dramatically with decreasing penetration depth. Surface effects related to two deformation mechanisms were proposed to be responsible for the observed inverse ISE on H and depth dependent m. Specifically, the mobility of screw dislocation/component and the diffusion length of interfacial diffusion were altered as the deformed region underneath the indenter was approaching the free surface, resulting in the unusual size effects in NC Mo.

Benefit of a Surface Nanocrystallization Treatment on Co28Cr6Mo Abrasive Wear Properties

In this work, the use of a nanocrystallization surface treatment is considered on a cobalt based alloy. Since the Co28Cr6Mo is widely used as an articular bearing surface for artificial joints like hip and knee prostheses, the improvement of its tribological properties is a matter of concern to extend the lifespan of implants. By means of SMA (Surface Mechanical Attrition) treatment, a nanostructured layer is formed at the surface of a CoCrMo alloy establishing an optimized hardness gradient down to a depth of a few hundred of microns. Different treatment times (5, 15 and 25 minutes) are assessed comparatively and several surface polishing methods are studied: with clothes, brushes and a liquid filled with abrasive particles. The influence of processing parameters is discussed regarding hardness and topography. Moreover, the impact of surface modification is examined in terms of wear strengthening through scratch testing. The use of increasing loads mode gives some evidence of the benefit of SMAT. A significant decrease of penetration depth is noticed, from 30% to 60% on average. A straight correlation is also noticed depending on the surface finish method. This study illustrates both the ability of micro scratch testing to assess comparatively treated surface layer and to highlight the benefit of SMAT for wear strengthening in an abrasive wear mode.

Scale effects of nanomechanical properties and deformation behavior of Au nanoparticle and thin film using depth sensing nanoindentation.

Nanoscale research of bulk solid surfaces, thin films and micro- and nano-objects has shown that mechanical properties are enhanced at smaller scales. Experimental studies that directly compare local with global deformation are lacking. In this research, spherical Au nanoparticles, 500 nm in diameter and 100 nm thick Au films were selected. Nanoindentation (local deformation) and compression tests (global deformation) were performed with a nanoindenter using a sharp Berkovich tip and a flat punch, respectively. Data from nanoindentation studies were compared with bulk to study scale effects. Nanoscale hardness of the film was found to be higher than the nanoparticles with both being higher than bulk. Both nanoparticles and film showed increasing hardness for decreasing penetration depth. For the film, creep and strain rate effects were observed. In comparison of nanoindentation and compression tests, more pop-ins during loading were observed during the nanoindentation of nanoparticles. Repeated compression tests of nanoparticles were performed that showed a strain hardening effect and increased pop-ins during subsequent loads.