Narrow Results

We study the superconductivity in MgB₂ using a tight binding model to investigate the doping dependence of the order parameter and the critical temperature. We consider both the anisotropic and the isotropic s-wave pairing to study the coexistence of the two gaps. A good agreement between the existing experiments and our theoretical curves is observed. The temperature dependence of order parameter, specific heat and penetration depth at half filling are also demonstrated and are found to be in accord with the available experimental predictions.

The large variety of the measured magnetic penetration depth is interpreted by using two microscopic gap models. We calculate the penetration depth of superconductor MgB₂ in low temperatures by using two gap and an anisotropic s-wave gap models. In the two gap model we consider that the total penetration depth is a weighted sum of the contribution from σ- and π-bands and the interaction between these two bands is ignored. The effect of impurities on the σ-band is less than that π-band and there are tremendous modifications of the temperature dependence of the penetration depth for π-band.

The magnetic penetration depth formula in MgB₂ is more complex than that in BCS superconductors due to the existence of exotic two energy gap in MgB₂. A new simplified relationship between the penetration depth and temperature is presented, which is derived from the two-fluid model by means of numerical fitting method, and the physical meaning is relatively clear.

We study the two-component Ginzburg–Landau (GL) theory, in the presence of a self-consistent vortex line, to obtain the penetration depth (λ) and the effective healing length (ξ), in the asymptotic limit r → ∞. All these parameters versus T/T_c are analyzed for the materials MgB₂, V₃Si and LiFeAs in the interval 0.88 ≤ T/T_c ≤ 1.0, where the GL theory is assumed to be valid. We find that κ ≡ λ/ξ, which is another parameter not related to the GL parameter, is T-independent for V₃Si and LiFeAs, while is T-dependent for the compound MgB₂. This result suggests that even though all these three materials display two-gap superconductivity overall, near T_c superconductivity in V₃Si and LiFeAs seems to be different from the one in MgB₂. The use of this parameter, κ, as a new way to "study" the superconducting materials, under the presence of a single vortex, is valid for 0.88T_c≲ T ≤ T_c, namely, in the GL formalism.

In this paper, a TMDC-based surface plasmon resonance (SPR) sensor for detecting fat concentration milk, incorporating an Ag-Pt (bimetallic) layer, is presented. The Pt (Platinum) layer provides chemical stability and increases sensitivity with the TMDC layer. Compared to the conventional SPR sensor, the maximum sensitivity, detection accuracy (DA), and figure of merit (FoM) of 314^∘/RIU, 0.142/degree, and FoM 44.05/RIU are achieved with the WS₂ layer. The sensor’s increased sensitivity is due to the increased field intensity and depth of penetration into the sensor layer, resulting in a larger interaction volume. The presence of the WS₂ layer, with its significant imaginary part of the dielectric constant, helps improve sensitivity and broadens the SPR curves. This broadening SPR curve ultimately affects the DA and FoM of the sensor. The capability of the proposed sensor to detect various biological analytes with a refractive index (1.3452–1.3657) can be demonstrated.

The general principles needed to compute the effect of a stationary gravitational field on the quasistationary electromagnetic phenomena in normal conductors and superconductors are formulated from general relativistic point of view. Generalization of the skin effect, that is the general relativistic modification of the penetration depth (of the time-dependent magnetic field in the conductor) due to its relativistic coupling to the gravitational field is obtained. The effect of the gravitational field on the penetration and coherence depths in superconductors is also studied. As an illustration of the foregoing general results, we discuss their application to superconducting systems in the outer core of neutron stars. The relevance of these effects to electrodynamics of magnetized neutron stars has been shown.

Titanium nitride (TiN) widely used as hard coating material was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The goal of this study was to examine the effect of ion etching with and without titanium (Ti) and chromium (Cr) on the adhesion strength of TiN coatings deposited on tool steels. From the scratch tester, it was observed that by increasing Ti ion etching showed an increase in adhesion strength of the deposited coatings. The coatings deposited with Cr ion etching showed poor adhesion compared with the coatings deposited with Ti ion etching. Scratch test measurements showed that the coating deposited with titanium ion etching for 16 min is the most stable coating and maintained even at the critical load of 66 N. The curve obtained via penetration depth along the scratch trace is linear in the case of HSS, whereas is slightly flexible in the case of D2 tool steel. The coatings deposited on HSS exhibit better adhesion compared with those on D2 tool steel.

This paper presents a simple analytical model for evaluation of penetration depth and resistant strength of concrete target. The model is based on the assumption that the deformation and failure of the projectile are negligible. Normal impact is assumed in the model. It is also assumed that the penetration is steady state within the time step, the momentum balance equation can be integrated, resulting in an explicit expression for the pressure at the target interface. The expressions for spherically symmetric cavity expansion for a material with locked hydrostatic stress and constant shear strength have been developed. The constants for failure criterion are derived based on Mohr–Coulomb and Tresca-limit yield line theories. Final depth of penetration has been derived using the results of spherically symmetric cavity expansion analysis, relating the radial stress at the cavity surface to cavity expansion velocity and Newton’s second law of motion. Target resistant strength parameter is expressed as a function of penetration depth, projectile velocity, nose performance coefficient, target density, mass of projectile, and radius of the projectile. The expressions for velocity, acceleration and displacement at any instant of time have been deduced based on total depth of penetration and target resistant strength. To validate the methodologies, numerical studies have been conducted and observed that the penetration depth and target resistant strength obtained in the present study are in good agreement with the corresponding experimental values reported in the literature. It is also observed that the time history of penetration depth and projectile velocity are in good agreement with the corresponding literature values.

The existing prediction methods of penetration depth do not take the influence of attack angle or angular velocity of projectile (i.e. effect of attack angle) into account. The main purpose of this work is to develop an approximate approach to predict the penetration depth for a rigid projectile into concrete target covered with yaw-inducing overlays. A quasi-static, elastic–plastic contact model of projectile impacting on irregular barrier is built based on Hertz’s contact theory, and the expression of effect of attack angle are also presented. The stress on projectile–target interface is derived according to spherical cavity expansion model and mechanical property of target, where reduction coefficient is introduced to consider the effect of free surface, and the penetration resistances are further obtained. Differential equations of motion for projectile arbitrarily oblique into target covered with yaw-inducing overlays are given by employing the initial conditions of projectile striking on irregular barrier. Then a simplified formula of depth-of-penetration (DOP) with effect of attack angle is presented by introducing an influence coefficient of oblique impact and an influence coefficient of yaw-inducing overlays into the depth of normal penetration. Predictions from the simplified formula are validated by comparison with ballistic experimental data for a 57mm diameter, 4.44kg, and ogive-nose, semi-armor-piercing with striking velocities between 320 and 705m/s.

Numerical investigations are conducted to examine the penetration depth of ellipsoid-shaped projectiles into semi-infinite aluminum targets under conditions of hypervelocity impact. These results are then compared against empirical equations developed by various researchers for spherical projectiles. The semi-infinite aluminum target, sized at $150\times 150\times 50$mm, is composed of Al7075-T651. The projectiles are fashioned from Al-7075-T651, steel, and boron carbide. The projectile’s shape factor was determined using the L/d ratio, specifically for the symmetrical ellipsoidal shape. Employing Ansys Autodyn, a 3-dimensional finite element model (FEM) is created and calibrated using existing experimental findings from the literature. The validation utilized the Johnson–Cook (JC) and Johnson–Holmquist (JH-2) material models for both the targets and projectiles. These validated models are subsequently employed to analyze how the ellipsoid projectile’s shape and density influenced their interaction with the semi-infinite targets. Furthermore, the investigation also encompassed an analysis of the resulting crater shapes generated by the hypervelocity impact of both metallic and nonmetallic projectiles. It is observed that for a definite SF, max${}^m$ depth of penetration is observed due to steel project as compared to boron carbide and aluminum projectile. Both the diameter of the crater and the height of the bulge ($H_c)$ are directly proportional to the impact velocity and density of projectiles, and inversely proportional to SF. However, for a particular material and impact velocity of the projectile, in the case of $H_c$, there are no clear-cut observations displayed it seems like a mixed variation.

This study focuses on achieving enhanced mechanical properties of the welded joints, which is critical for the applications of mild steel (MS) plates in various industries. In this regard, a systematic approach is used to adjust welding parameters such as welding current and workpiece thickness in shielded metal arc welding (SMAW), with the objective of identifying the optimal combination that maximizes weld quality. The experiments were planned with the help of Taguchi’s L9 orthogonal array method in order to reduce experimental cost and time. The weld quality is optimized by determining the signal-to-noise ratios of weld penetration, tensile strength, impact strength, and microhardness for each experimental sample. As a result, 110 A welding current is obtained as the optimal SMAW parameter for a 5 mm thick MS IS 2062 Grade B plate. This optimized result has also achieved 394.78 N/mm² tensile strength and 53 J of impact resistance for the respective specimen. Besides, research not only enhances understanding of the SMAW process but also offers practical implications for industries requiring high-performance welded joints in MS structures. Additionally, this study can assist upcoming researchers in optimizing any existing welding procedures.

Optical clearing improves the penetration depth of optical measurements in turbid tissues. Polarization imaging has been demonstrated as a potentially promising tool for detecting cancers in superficial tissues, but its limited depth of detection is a major obstacle to the effective application in clinical diagnosis. In the present paper, detection depths of two polarization imaging methods, i.e., rotating linear polarization imaging (RLPI) and degree of polarization imaging (DOPI), are examined quantitatively using both experiments and Monte Carlo simulations. The results show that the contrast curves of RLPI and DOPI are different. The characteristic depth of DOPI scales with transport mean free path length, and that of RLPI increases slightly with g. Both characteristic depths of RLPI and DOPI are on the order of transport mean free path length and the former is almost twice as large as the latter. It is expected that they should have different response to optical clearing process in tissues.

Light has been clinically utilized as a stimulation in medical treatment, such as Low-level laser therapy and photodynamic therapy, which has been more and more widely accepted in public. The penetration depth of the treatment light is important for precision treatment and safety control. The issue of light penetration has been highlighted in biomedical optics field for decades. However, quantitative research is sparse and even there are conflicts of view on the capability of near-infrared light penetration into brain tissue. This study attempts to quantitatively revisit this issue by innovative high-realistic 3D Monte Carlo modeling of stimulated light penetration within high-precision Visible Chinese human head. The properties of light, such as its wavelength, illumination profile and size are concern in this study. We made straightforward and quantitative comparisons among the effects by the light properties (i.e., wavelengths: 660, 810 and 980nm; beam types: Gaussian and flat beam; beam diameters: 0, 2, 4 and 6cm) which are in the range of light treatment. The findings include about 3% of light dosage within brain tissue; the combination of Gaussian beam and 810nm light make the maximum light penetration ($>5$cm), which allows light to cross through gray matter into white mater. This study offered us, the first time as we know, quantitative guide for light stimulation parameter optimization in medical treatment.

In this study, we analyzed internal and external skin temperatures as well as penetration depths for the different treatment conditions regarding the 1064 nm Nd:YAG laser to find the optimum treatment condition for skin rejuvenation. We transmitted the laser into a skin mimicking phantom with laser fluence conditions of 26, 30 and 36 J/cm², and spot diameter conditions of 8 and 10 mm. We also selected the pulse duration as 30 ms, and measured internal–external skin temperatures and penetration depths. To examine the distribution of internal–external skin temperatures, we performed a heat transfer analysis based on the finite element method. Skin layers were designed as three-dimensional models to predict skin temperatures more accurately. We employed the same laser conditions of fluence and spot diameter while performing actual and simulation analyses. Consequently, we found that laser conditions for a spot diameter of 8 mm with a fluence of 36 J/cm² and a spot diameter of 10 mm with a fluence of 26 and 30 J/cm² demonstrate the greatest effectiveness toward skin rejuvenation. Moreover, the penetration depths and the range of thermal distribution increased as the fluence and spot diameter increased. In particular, the spot diameter influenced the therapeutic effects more seriously than the fluence.