Variation Of Penetration Depth Research Articles

Parameter-based transfer learning for severity classification of atopic dermatitis using hyperspectral imaging.

Because atopic dermatitis (AD) is a chronic inflammatory skin condition that causes structural changes, there is a growing need for noninvasive research methods to evaluate this condition. Hyperspectral imaging (HSI) captures skin structure features by exploiting light wavelength variations in penetration depth. In this study, parameter-based transfer learning was deployed to classify the severity of AD using HSI. Therefore, we aimed to obtain an optimal combination of classification results from the four models after constructing different source- and target-domain datasets. We designated psoriasis, skin cancer, eczema, and AD datasets as the source datasets, and the set of images acquired via hyperspectral camera as the target dataset for wavelength-specific AD classification. We compared the severity classification performances of 96 combinations of sources, models, and targets. The highest classification performance of 83% was achieved when ResNet50 was trained on the augmented psoriasis dataset as the source, with the resulting parameters used to train the model on the target Near-infrared radiation (NIR) dataset. The second highest classification accuracy of 81% was achieved when ResNet50 was trained on the unaugmented psoriasis dataset as the source, with the resulting parameters used to train the model on the target R dataset. ResNet50 demonstrated potential as a generalized model for both the source and target data, also confirming that the psoriasis dataset is an effective training resource. The present study not only demonstrates the feasibility of the severity classification of AD based on hyperspectral images, but also showcases combinations and research scalability for domain exploration.

Study on Penetration Mechanism of Shaped-Charge Jet under Dynamic Conditions.

Aiming at the dynamic penetration process of a shaped-charge jet, we proposed a mathematical model for the penetration of a jet under dynamical conditions based on the theory of virtual origin and the Bernoulli equation taking into account the jet and target intensities. The dynamic penetration process of the jet was divided according to the penetration channel of the jet into the static target. The dynamic penetration model of the jet based on the unperturbed section and perturbed section was established. The penetration depth variation in the shaped-charge jet vertically penetrating target plates with different moving speeds (150~400 m/s) was analyzed by finite element software. The dynamic penetration model shows that with the increase in the target moving speed, the disturbed time of the jet continuously advances, and the dynamic penetration depth continuously decreases; as the velocity of the target increases, the penetration length of the unperturbed jet decreases and then becomes stable, while the penetration length of the perturbed jet decreases. The results showed that the mathematical model is consistent with the finite element simulation, and that the mathematical model can effectively characterize the penetration depth of the unperturbed and disturbed jet portions, adequately explain the dynamic response behavior of the jet penetrating a moving target, and effectively predict the dynamic penetration depth of the jet under the influence of the target movement.

Strong Coupling Superconductivity in Ca-Intercalated Bilayer Graphene on SiC.

The metal-intercalated bilayer graphene has a flat band with a high density of states near the Fermi energy and thus is anticipated to exhibit an enhanced strong correlation effect and associated fascinating phenomena, including superconductivity. By using a self-developed multifunctional scanning tunneling microscope, we succeeded in observing the superconducting energy gap and diamagnetic response of a Ca-intercalated bilayer graphene below a critical temperature of 8.83 K. The revealed high value of gap ratio, 2Δ/kBTc ≈ 5.0, indicates a strong coupling superconductivity, while the variation of penetration depth with temperature and magnetic field indicates an isotropic s-wave superconductor. These results provide crucial experimental clues for understanding the origin and mechanism of superconductivity in carrier-doped graphene.

A study of the magnetohydrodynamic effect on keyhole dynamics and defect mitigation in laser beam welding

In this paper, the highly transient keyhole dynamics, e.g., laser absorption, keyhole geometry, and fluctuation, etc., under a magnetic field are investigated using an experimental approach and multi-physical modeling. The model provides accurate predictions to the variation of penetration depth and weld pool profiles caused by the MHD effect, which is validated by the measurements of optical micrographs and in-situ metal/glass observation. The micro-X-ray computed tomography shows a remarkable reduction of keyhole-induced porosity with the magnetic field. The correlation between the porosity mitigation and the weld pool dynamics influenced by the magnetic field is built comprehensively. It is found that the magnetic field gives a direct impact on the laser energy absorption at the keyhole front wall by changing the protrusion movement. The porosity mitigation comes from multiple physical aspects, including keyhole stabilization, widening of the bubble floating channel, and the electromagnetic expulsive force. Their contributions vary according to the bubble size. The findings provide a deeper insight into the relationship between electromagnetic parameters, keyhole dynamics, and suppression of keyhole-relevant defects.

The interaction of high-power fiber laser irradiation with intrusive rocks

Laser cutting of intrusive rocks, including granite, gabbro, and diorite, is carried out in order to assess the cut characteristics through geometrical measurements, such as kerf width, melting width, and penetration depth. The absorption rate for each specimen at the wavelength of 1064 nm is measured using a spectrophotometer. A multimode fiber laser is used in this study with the power of 9 kW and different cutting speeds. Furthermore, nitrogen gas at 13 bar is applied as the assistant gas in order to remove the melted material effectively. As a result of the experiment, the relationship between the cutting speed and geometrical measurements is investigated. Furthermore, variations of penetration depth are performed in accordance with the number of laser cuts. In addition, through energy dispersive X-ray (EDX) element mapping, minerals that comprise the rocks are classified and characterized. Subsequently, the changes in the microstructure and chemical composition of each specimen, before and after laser cutting, are compared using scanning electron microscope (SEM) and EDX analyses. Experimental results demonstrate that the cutting characteristics vary, depending on the types of minerals that make up the rock. Based on a series of tests, it is identified that volume energy of more than 3.06E + 13 mathrm{J}/{mathrm{m}}^{3} is required to fully cut intrusive rocks that have a thickness of 25 mm.

Design Implications and Opportunities of Considering Fatigue Strength, Manufacturing Variations and Predictive LCC in Welds

Fatigue strength dictates life and cost of welded structures and is often a direct result of initial manufacturing variations and defects. This paper addresses this coupling through proposing and applying the methodology of predictive life-cycle costing (PLCC) to evaluate a welded structure exhibiting manufacturing-induced variations in penetration depth. It is found that if a full-width crack is a fact, a 50% thicker design can result in life-cycle cost reductions of 60% due to reduced repair costs. The paper demonstrates the importance of incorporating manufacturing variations in an early design stage to ensure an overall minimized life-cycle cost.

Structural, optical, and dielectric properties for Mg0·6Cu0·2Ni0·2Cr2O4 chromite spinel

In this work, the structural, optical, and dielectric properties for Mg0·6Cu0·2Ni0·2Cr2O4 chromite sample prepared by sol-gel process were investigated. The XRD characterization for this sample confirmed the development of the face-centered cubic spinel structure with Fd3‾m space group. From the UV–Vis optical absorbance, the synthesized chromite shows significantly lower direct band gap energy and has an appropriate absorption rate in the visible light region. The variations of penetration depth, extinction coefficient, refractive coefficient, dispersion energy parameters, and dielectric permittivity constants were also interpreted. The Non-Overlapping Small Polaron Tunneling (NSPT) and the Correlated Barrier Hopping (CBH) are the suitable models to describe the conduction process for the prepared sample. The behavior of dielectric constants has been interpreted based on the Maxwell-Wagner's theory of interfacial polarization. The behavior of imaginary part of impedance (Z″) shows a dielectric-relaxation phenomenon in the sample with activation energies near to those determined from the conductivity study.

Microscratch of copper by a Rockwell C diamond indenter under a constant load

The scratch test is used for quality control mostly in phenomenological ways, and whether fracture toughness can be obtained from this test is still a matter of debate requiring further elucidation. In this paper, values of the fracture toughness of copper obtained by different scratch-based approaches are compared in order to examine the applicability of scratch-based methodologies to characterize the fracture toughness of soft metals. The scratch response of copper to a Rockwell C diamond indenter is studied under a constant normal load condition. The variations of penetration depth, residual depth, and residual scratch width with applied normal load are quantified from spherical to sphero-conical contact regimes by piecewise functions. A newly proposed size effect law is found to be the most suitable for scratch-based approaches to characterizing the fracture toughness of soft metallic materials with significant plasticity. A simple expression relating the nominal stress to the penetration depth is proposed for the spherical contact regime and gives almost the same value of fracture toughness. The residual scratch width provides useful information on pile-up of material and on the spherical tip radius of the indenter. It is found that the values of the fracture toughness obtained from the microscratch test are influenced by the data range for analysis.

Environmental lumping for efficient fatigue assessment of large-diameter monopile wind turbines

Fatigue damage is one of the governing factors for the design of offshore wind turbines. However, the full fatigue assessment is a time-consuming task. During the design process, the site-specific environmental parameters are usually condensed by a lumping process to reduce the computational effort. Preservation of fatigue damage during lumping requires an accurate consideration of the met-ocean climate and the dynamic response of the structure. Two lumping methods (time-domain and frequency-domain) have been evaluated for a monopile-based 10 MW offshore wind turbine, both based on damage-equivalent contour lines. Fatigue damage from lumped load cases was compared to full long-term fatigue assessment. The lumping methods had an accuracy of 94–98% for the total long-term fatigue damage and 90% for individual wind speed classes, for aligned wind and waves. Fatigue damage was preserved with the same accuracy levels for the whole support structure. A significant reduction of computational time (93%) was achieved compared to a full long-term fatigue assessment. For the cases with 30° and 60° wind-wave misalignment, there was a mean underestimation of approximately 10%. Variations in penetration depth did not affect the selection of the lumped sea-state parameters. This work presents a straightforward method for the selection of damage-equivalent lumped load cases, which can adequately preserve long-term fatigue damage throughout the support structure, providing considerable reduction of computational effort.

Variability of Cutting and Thermal Dynamics Between New and Used Acetabular Reamers During Total Hip Arthroplasty.

BackgroundAseptic loosening of the acetabular component remains one of the leading causes of early failure of total hip arthroplasty. Poor apposition of bone onto the implant surface can be due to inaccurate reaming and osteonecrosis of the acetabular bone due to the heat generated while reaming.MethodsNew and used acetabular reamers were tested on an MTS system using a clinically relevant force of 87.6 N. A thermal profile and depth achieved by the reamers were analyzed and compared between the 2 cohorts. Heat generated and force required for the community used reamers to achieve the same depth as the new reamers were subsequently analyzed.ResultsThe new reamers achieved a depth 3.4 mm deeper than the community reamers (P < .001). The new reamers generated 4.1°C less heat than the community reamers (P = .007) under the same force and time. When programmed to ream to the average depth of the new reamers, the community reamers generated 16.8°C more heat (P = .002) and required forces 95-318% greater than the 87.6 N force used by the new reamers.ConclusionsCommunity use of reamers will cause variations in depth of penetration and increased temperatures at a clinically generated force vs new reamers. When community reamers were forced to the same depths the new reamers achieved, a significantly greater amount of heat was generated, and an increased amount of time was needed, both of which are known risk factors for osteonecrosis.

A probabilistic model of weld penetration depth based on process parameters

In welded structures using robotized metal active gas (MAG) welding, unwanted variation in penetration depth is typically observed. This is due to uncertainties in the process parameters which cannot be fully controlled. In this work, an analytical probabilistic model is developed to predict the probability of satisfying a target penetration, in the presence of these uncertainties. The proposed probabilistic model incorporates both aleatory process parameter uncertainties and epistemic measurement uncertainties. The latter is evaluated using a novel digital tool for weld penetration measurement. The applicability of the model is demonstrated on fillet welds based on an experimental investigation. The studied input process parameters are voltage, current, travel speed, and torch travel angle. The uncertainties in these parameters are modelled using adequate probability distributions and a statistical correlation based on the volt-ampere characteristic of the power source. Using the proposed probabilistic model, it is shown that a traditional deterministic approach in setting the input process parameters typically results in only a 50% probability of satisfying a target penetration level. It is also shown that, using the proposed expressions, process parameter set-ups satisfying a desired probability level can be simply identified. Furthermore, the contribution of the input uncertainties to the variation of weld penetration is quantified. This work paves the way to make effective use of the robotic welding, by targeting a specified probability of satisfying a desired weld penetration depth as well as predicting its variation.

Round robin using the depth of penetration test method on an armour grade alumina

Abstract The depth of penetration (DOP) method is a well-known ballistic test method for characterisation and ranking of ceramic armour materials. The ceramic tile is bonded to a backing material of semi-infinite thickness, and the penetration depth of the projectile gives a measure of the performance of the ceramic. There is, however, an inherent variability in the results from this test method. In this work, the accuracy and the variability of the DOP method has been investigated in a round robin exercise. Six ballistic test centres took part in the exercise. A test protocol was developed, in which the threat type (projectile and impact conditions) and a procedure on how to prepare the targets were specified. The targets consisted of alumina tiles of two different thicknesses that were bonded to polycarbonate backing cubes. Two different 7.62 mm armour piercing projectiles were employed; one with a hard steel core and one with a tungsten carbide core. The projectiles and the other materials all came from single material batches in order to avoid batch-to-batch variations in material properties. These materials were distributed between the ballistic test centres. The test results of the different ballistic test facilities were collected and compared. There was not a lot of variation between the average DOP values obtained at each laboratory, but the variation in penetration depth between shots was high. The consequence of this variation may be less confidence in the test results, and a statistical method was used to evaluate the required number of tests that are sufficient to obtain an average result with high confidence. In most cases, the required number of tests is much higher than what is practically feasible. This work was conducted as part of the European Defence Agency-project CERAMBALL.

Shaped charge penetration into high- and ultrahigh-strength Steel–Fiber reactive powder concrete targets

Abstract Experiments on shaped charge penetration into high and ultrahigh strength steel-fiber reactive powder concrete (RPC) targets were performed in this paper. Results show that the variation of penetration depth and crater diameter with concrete strength is different from that of shaped charge penetration into normal strength concrete (NSC). The crater diameter of RPC is smaller than that of NSC penetrated by the shaped charge. The jet particles are strongly disturbed and hardly reach the crater bottom because they pass through the narrow channel formed by jet penetration into the RPC. The effects of radial drift velocity and gap effects of jet particles for a shaped charge penetration into RPC target are discussed. Moreover, a theoretical model is presented to describe the penetration of shaped charge into RPC target. As the concrete strength increases, the penetration resistance increases and the entrance crater diameter decreases. Given the drift velocity and narrow crater channel, the low-velocity jet particles can hardly reach the crater bottom to increase the penetration depth. Moreover, the narrow channel has a stronger interference to the jet particles with increasing concrete strength; hence, the gap effects must be considered. The drift velocity and gap effects, which are the same as penetration resistance, also have significant effects during the process of shaped charge penetration into ultrahigh-strength concrete. The crater profiles are calculated through a theoretical model, and the results are in good agreement with the experiments.

Prediction of penetration in one-sided fillet welds by in-process joint gap monitoring\u2014an experimental study

The challenge to predict variations in penetration depth in one-sided fillet welds during robotized gas metal arc welding has been addressed by a pilot investigation of technical possibilities and limitations. The main cause for the variation in penetration depth is considered to be variation in joint gap size. Special attention has been paid in order to adopt the experimental conditions to conform to industrial welding conditions. The employed method uses in-process monitoring of joint gap size together with an empirical model relating penetration depth to gap size in order to predict this depth. The gap size estimates are based on image information from two cameras, one visual and one infrared. The results, that are evaluated off-line, confirm the development of a real-time method providing technical solutions that are industrially tractable. The results also pinpoint areas of further improvements towards increased robustness and reduced estimation uncertainties.

Investigation of molecular penetration depth variation with SMBI fluxes**Project supported by the National Natural Science Foundation of China (Grant Nos. 11375053, 11575055, 11405022, and 11405112), the Chinese National Fusion Project for ITER (Grant Nos. 2013GB107001 and 2013GB112005), the International S&T Cooperation Program of China (Grant No. 2015DFA61760), and the Funds of the Youth Innovation Team of Science and Technology in

We study the molecular penetration depth variation with the SMBI fluxes. The molecular transport process and the penetration depth during SMBI with various injection velocities and densities are simulated and compared. It is found that the penetration depth of molecules strongly depends on the radial convective transport of SMBI and it increases with the increase of the injection velocity. The penetration depth does not vary much once the SMBI injection density is larger than a critical value due to the dramatic increase of the dissociation rate on the fueling path. An effective way to improve the SMBI penetration depth has been predicted, which is SMBI with a large radial injection velocity and a lower molecule injection density than the critical density.

Modeling and robust controlling of laser welding process on high strength titanium alloy using fuzzy basis function networks and robust Takagi-Sugeno fuzzy controller

The purpose of this paper is to present and implement a novel approach to data-driven modeling and robust control of a laser keyhole welding process. The objective is to maintain the penetration depth of the laser welding process at a desired value under system uncertainties. A framework was proposed to estimate the keyhole diameter and the keyhole penetration depth in real time by type-1 and type-2 fuzzy basis function networks, and an adaptive divided difference filter. A robust Takagi-Sugeno fuzzy controller was implemented to adjust the laser power of the welding process. Experimental results demonstrated that the fuzzy models provided an accurate estimation of both the welding geometry and its variations due to uncertainties, and the robust Takagi-Sugeno fuzzy controller successfully reduced the penetration depth variation and improved the quality of the welding process.

Explanation of penetration depth variation during laser welding under variable ambient pressure

It has been observed that the penetration depth during laser welding (LW) under vacuum or reduced ambient pressure could be significantly greater than that during welding under atmospheric pressure. Previous explanations of this phenomenon usually limit to specific wavelength laser welding and have difficulties in explaining why the variation will disappear, as the welding speed increases. Here, we propose that this variation is caused by the temperature difference of keyhole wall under variable ambient pressure based on a correct physical description of related processes. A new surface pressure model, dependent on ambient pressure, is proposed for describing the evaporation process during laser material interaction under variable ambient pressure. For laser welding of a 304 stainless steel with 2.0 kW laser power and 3 m/min welding speed, it is shown that the average keyhole wall temperature is around 2900 K under atmospheric pressure, and only around 2300 K under vacuum, which results in significant penetration depth variations. Interestingly, it is also shown that as the welding speed increases, the average temperature of the front keyhole wall gradually rises due to the reduction of the mean incident angle of laser, and the magnitude of this increase is larger in welding under vacuum than under atmospheric pressure. It allows us to explain why the penetration depth improvement decreases to zero with the increase of welding speed.

Temperature and Moisture Dependence of the Dielectric Properties of Silica Sand

The major objective of this work was to investigate the effects of temperature and moisture content on the dielectric properties of silica sand. The dielectric properties of moist silica sand at five temperatures between 20 to 100 °C, covering different moisture content levels at a frequency of 2.45 GHz, were measured with an open-ended coaxial probe dielectric measurement system. The wave penetration depth was calculated based on the measured dielectric data. The results show moisture content to be the major influencing factor for the variation of dielectric properties. Dielectric constant, loss factor and loss tangent all increase linearly with increasing moisture content. Three predictive empirical models were developed to relate the dielectric constant, loss factor, loss tangent of silica sand as a linear function of moisture content. An increase in temperature between 20 to 100 °C was found to increase the dielectric constant and loss factor. The penetration depth decreased with increase in moisture content and temperature. Variation in penetration depth was found to vary linearly with decrease in moisture content. An predictive empirical model was developed to calculate penetration depth for silica sand.This study offers useful information on dielectric properties of silica sand for developing microwave drying applications in mineral processing towards designing better microwave sensors for measuring silica sand moisture content.

Variable penetration depth of interferometric synthetic aperture radar signals on Alaska glaciers: a cold surface layer hypothesis

AbstractP-band interferometric synthetic aperture radar (InSAR) data at 5 m resolution from Kahiltna Glacier, the largest glacier in the Alaska Range, Alaska, USA, show pronounced spatial variation in penetration depth, δP. We obtained δP by differencing X- and P-band digital elevation models. δP varied significantly over the glacier, but it was possible to distinguish representative zones. In the accumulation area, δP decreased with decreasing elevation from 18 ± 3 m in the percolation zone to 10 ± 4 m in the wet snow zone. In the central portion of the ablation area, a location free of debris and crevasses, we identified a zone of very high δP (34 ± 4 m) which decreased at lower elevations (23 ± 3 m in bare ice and 5-10m in debris-covered ice). We observe that the spatial configuration of δP is consistent with the expected thermal regime of each zone: δP is high in areas where cold firn/ice likely occurs (i.e. percolation zone and upper ablation area) and low in areas where temperate surface firn/ice likely exists (wet snow zone and lower ablation area). We suggest that the very high δP observed in the upper ablation area is due to the presence of a cold surface layer.

Effect of oxygen deficiency on the magnetic field-dependent entropy in YBa2Cu3O7−δ

Roulin et al (1988), in one of their experimental papers, have presented a study of field-dependent entropy of high-purity YBa2Cu3O7 − δ (YBCO) as a function of oxygen deficiency. In order to explain their experimental results, we have used phenomenological GL-theory of anisotropic HTSCs in the London limit in line with of our earlier paper (Pattanaik et al, Physica B405, 3234 (2010)). Moreover, to account for the applicability of the theory at high field, we have incorporated the effect of vortex overlapping in the London theory done by Nanda (1995). Here, we have presented the variation of change in entropy (ΔS) with magnetic field for different oxygen deficiencies δ = 0, 0.04, and 0.06. On comparison, we found that our results are in good agreement with the experimental data of Roulin et al (1988). The variation of penetration depth (λ) and anisotropic ratio of effective masses (γ) with concentration is also presented.