Thickness Profile Research Articles

Drying Liquid Coatings with an Evaporation Mask: Theory and Experiments.

We report a study of the spatially varying thickness of dried films of polymer solutions resulting from a nonuniform evaporation flux. The controlled heterogeneity of the evaporation flux is imposed by placing a solid mask above the evaporating film spread on a solid substrate. At the end of drying, a depression has formed under the mask, together with overthicknesses extending from the edge of the mask and over distances that may be larger than its size. By considering the flows induced in a vertically homogeneous film, we obtain analytical solutions for the thickness profiles during drying using a linear approximation in the limits of either gravity or capillarity-driven flows. We demonstrate that gravity can play a role in the deformations of the films, even if their initial thicknesses are 1 order of magnitude smaller than the capillary length. In addition, we examine two possible reference states for the linear approximation, i.e., far from the mask in the film of decreasing thickness and increasing viscosity, or under the mask where no evaporation occurs. We further compare these results with experimental ones obtained by drying thin films of polymer solutions under a mask. Both the extent and amplitude of the thickness heterogeneities of the dry film are quantitatively predicted by the linear analysis for a reference state under the mask. Our results therefore provide new insight on the patterns resulting from evaporation masks and can be generalized to minimize thickness heterogeneities in any situation in which the evaporation flux is nonuniform.

Experimental and LBM simulation study on the bubble dynamic behaviors in subcooled flow boiling

Bubble dynamic behavior is a fundamental issue in comprehending flow boiling process. In this paper, the bubble characteristics are studied in depth through experiment in conjunction with the Lattice Boltzmann method (LBM). Firstly, the visualized experiment in rectangular channels with double heating plates is performed during subcooled flow boiling. High-speed camera is employed to directly capture the macroscopic bubble dynamic behaviors under different working conditions. Furthermore, LBM model with a novel hybrid boundary scheme is developed to investigate mesoscopic bubble characteristics, including contact diameter, microlayer thickness profile and superheated layer thickness. The bubble diameter from LBM model is compared to experimental data with a mean relative error of 10.8%. The results of the current research find that the bubbles nucleating on the inside channel have smaller contact diameter ratio and larger inclined angle. Finally, combining macroscopic experiments and mesoscopic LBM studies, a model of the bubble growth rate is proposed for predicting bubble growth behavior. In the process of model development, three aspects for deciding the bubble growth rate are considered, including microlayer evaporation, heat diffusion from the superheated liquid layer, and condensation at bubble dome caused by subcooled flow boiling. The prediction model agrees well with the experimental results, with a mean relative error of 14.7%. The established bubble growth model will help to predict the heat transfer process during flow boiling.

Evaluation of local and distortional buckling strength of purlins with paired torsion bracing using Direct Strength Method

In this paper, the authors presented a methodology to predict the local and distortional buckling strength of purlins with paired torsion bracing using the Direct Strength Method. The procedure is based on the component stiffness method that utilizes a displacement compatibility approach to calculate the anchorage forces in a purlin system. The procedure considers the partial diaphragm restraint provided by the sheathing and incorporates both first order and approximate second order torsion effects to predict the actual distribution of stresses along the cross section of the purlin. This distribution of stresses can vary substantially from the conventionally assumed constrained bending distribution and thus, correspondingly, the predicted local and distortional buckling strength can differ substantially.To validate the methodology, the procedure has been used to predict the strength of a series of 12 base tests. The test series included 8 in. (203 mm) and 10 in. (254 mm) deep lipped Z-sections with both thin (0.057 in, 1.45 mm) and thick (0.100 in, 2.54 mm) profiles. The same standing seam deck and clips were used in all the tests. The detailed investigation into the behavior of the base test revealed several slight load imbalances that, when properly accounted for, can have an impact on the predicted strength. The comparison between the tested strength and predicted strength showed good correlation and the methodology was largely able to predict test anomalies such as failures at the brace location versus the mid-span and failures of the eave purlin versus the ridge purlin. The prediction methodology ignores the additional torsional restraint provided by the sheathing and thus generally resulted in a slightly conservative approximation of the local and distortional buckling strength.

Morphological and Morphometric Analysis of Canine Choroidal Layers Using Spectral Domain Optical Coherence Tomography.

The choroid, a multifunctional tissue, has been the focus of research interest for many scientists. Its morphology and morphometry facilitate an understanding of pathological processes within both the choroid and retina. This study aimed to determine the choroidal layer thicknesses in healthy, mixed-breed mesocephalic dogs, both male (M) and female (F), using spectral domain optical coherence tomography (SD-OCT) with radial, cross-sectional, and linear scans. The dogs were divided into two groups based on age: middle-aged (MA) and senior (SN). Thicknesses of choroidal layers, namely RPE-Bruch's membrane-choriocapillaris complex (RPE-BmCc) with tapetum lucidum in the tapetal fundus, the medium-sized vessel layer (MSVL), and the large vessel layer with lamina suprachoroidea (LVLS), as well as whole choroidal thickness (WCT), were measured manually using the caliper function integrated into the OCT software. Measurement was performed dorsally and ventrally at a distance of 5000-6000 μm temporally and nasally at a distance of 4000-7000 μm to the optic disc on enhanced depth scans. The measurements were conducted temporally and nasally in both the tapetal (temporal tapetal: TempT, nasal tapetal: NasT) and nontapetal (temporal nontapetal: TempNT, nasal nontapetal: NasNT) fundus. The ratio of the MSVL thickness to the LVLS thickness for each region was calculated. In all examined dogs, the RPE-BmCc in the dorsal (D) region and MSVL in the Tt region were significantly thicker than those in the other regions. The MSVL was thinner in the ventral (V) region than in the D, TempT, TempNT and NasT regions. The MSVL was significantly thinner in the NasNT region than in the D region. LVLS thickness and WCT were significantly greater in the D and TempT regions than those in the other regions and significantly lesser in the V region than those in the other regions. The MSVL-to-LVLS thickness ratio did not differ between the age groups. Our results reveal that the choroidal thickness profile does not depend on age. Our findings can be used to document the emergence and development of various choroidal diseases in dogs in the future.

Modelling peatland development in high-boreal Quebec, Canada, with DigiBog_Boreal

DigiBog is a numerical model that simulates peat accumulation in temperate peatlands. Here, we modify DigiBog for boreal peatlands (DigiBog_Boreal) by accounting for snow cover, short growing seasons and groundwater exchanges between the peat and the aquifer. DigiBog_Boreal is then used to replicate ∼6500 years of peat accumulation at two high boreal latitude peatlands in Quebec, Canada. DigiBog_Boreal was driven with a weather generator and climate models, while peat cores from the sites were used to develop initial conditions and calibrate DigiBog_Boreal. Our results demonstrate that DigiBog_Boreal can replicate well peat thickness and age-depth profiles but cannot produce long-term fluctuations in water-table depths. Here, a possible explanation for DigiBog_Boreal's underperformance is the stability in the climatic drivers and less likely the new model developments. The results also indicate that peat decomposition and accumulation in DigiBog_Boreal are sensitive to water stored on the peat surface.

Using vortex generators for flow separation control on tidal turbine profiles and blades

Tidal energy can play an important role in the Net Zero transition. Increasing tidal turbine performance through innovation is crucial if the cost of tidal energy is to become competitive compared to other sources of energy. The present investigation is a proof-of-concept study for the application of Vortex Generators (VGs) on tidal turbines in view of increasing their performance. The more mature wind energy industry uses passive VGs either as a retrofit or in the blade design process to reduce separation at the inboard part of wind turbine blades. Tidal turbine blades also experience flow separation and here we examine whether passive vane VGs can be used to reduce or suppress that separated flow. First, a wind tunnel investigation is performed to assess the performance of VGs on a 20% thick profile from the blade. Then, the VG effect on the 2D-profile is modelled in a Reynolds Averaged Navier-Stokes in-house solver. Results show that low profile VGs, i.e. VGs shorter than the local boundary layer, can increase the performance of the blade profile and successfully reduce flow separation. The VG effect on blade performance is examined in model scale and in full-size. VGs successfully suppress separation in both cases and it is shown that full-size information should be used for the placement of VGs. A maximum power coefficient increase of 1.05% is observed at a tip speed ratio of λ=3. The present proof-of-concept study demonstrates for the first time the potential of passive VGs to be included either in the design process of a tidal turbine blade or as a retrofit solution.

RETRACTED: A tropical soil (Ferralsol) identified in the northernmost part of the Mediterranean (Istria, Croatia)

Terra rossa soils on the Istrian peninsula are generally considered polygenetic relict soils. They overlie and mark the youngest subaerial unconformity in the northwestern part of the Adriatic Carbonate Platform and are susceptible to erosional and redepositional processes. Terra rossa soils represent a valuable archive of information that can be used to understand present and past soil formation processes in the context of climate variability and landscape dynamics, especially in low-lying parts of the karst landscape where thicker deposits are typically found. We studied a 3 m thick terra rossa profile in a karst depression on the northernmost part of the southwestern Istrian planation surface and analysed the micromorphology, physical/chemical properties, geochemistry, bulk and clay mineralogy, and composition of heavy and light mineral fractions. The profile shows several signs of colluviation and polygenesis with clay distribution along the profile, clearly indicating lithic discontinuities. Kaolinization, along with iron oxide formation, is the dominant process in the studied profile. Ferralitization and lessivage processes were diagnosed throughout the profile, with intense clay translocation occurring despite the extremely stable soil microaggregates. In accordance with the WRB system, the profile is classified as Lixic Rhodic Ferralsol (Clayic, Aric). This implies that some terra rossa soils, previously classified as e.g. Cambisols or Luvisols, might actually be Ferralsols or other tropical soils (e.g. Lixisols), in which relict properties are preserved in the present climate. The finding of a Ferralsol in the study area indicates the old age of the surface of the karst depression and provides the first data on the burial history of the southwestern Istrian planation surface. We suggest the older Quaternary interglacials, the mid-Piacenzian Warm Period (Pliocene) and the Miocene Climatic Optimum as favourable periods for the formation of the studied soil.

Systematic and Temporal Geochemical Changes in the Upper Deccan Lavas: Implications for the Magma Plumbing System of Flood Basalt Provinces

AbstractLarge Igneous Provinces (LIPs) are unusual volcanic events in which massive amounts of melt (∼106 km3) erupt in relatively short time periods (<106 years). Most LIP magmas have undergone extensive fractional crystallization and crustal contamination, but the crustal magmatic plumbing systems and the processes triggering eruptions are poorly understood. We present new major and trace element and radiogenic isotope data for 43 individual lava flows from a continuous 1,200 m thick stratigraphic profile through the upper, most voluminous part of the Deccan LIP (Bushe to Mahabaleshwar Formations). Eruption rates for this section are constrained by published paleomagnetic directions and absolute U‐Pb ages for zircons from weathered flow tops exposed in the profile. We find four magmatic sequences each lasting ∼104–∼105 years during which major and trace element compositions change systematically, followed by an abrupt change in geochemistry at the start of a new sequence. Within each sequence, the MgO content and proportion of crustal contamination decrease progressively, indicating a continuous replenishment of the associated magma reservoirs with less contaminated but more evolved melts. These geochemical signatures are best explained by repeated episodes of melt recharge, mixing, and eruption of variably evolved magmas originating from relatively small magma reservoir located in different crustal levels.

Estimation of the Thickness Profile of a Human Skull Phantom by Ultrasound Methods Using a Two-Dimensional Array

Estimation of the Thickness Profile of a Human Skull Phantom by Ultrasound Methods Using a Two-Dimensional Array

Disk wakes in nonlinear stratification

Nonlinearity of density stratification modulates buoyancy effects. We report results from a body-inclusive large eddy simulation of a wake in nonlinear stratification, specifically for a circular disk at diameter-based Reynolds number ( ${\it Re} $ ) of $5000$ . Five density profiles are considered; the benchmark has linear stratification and the other four have hyperbolic tangent profiles of the same thickness to model a pycnocline. The disk moves inside the central core of the pycnocline in two of those four cases and, in the other two cases with a shifted density profile, the disk moves partially/completely outside the pycnocline. The maximum buoyancy frequency ( $N_{max}$ ) for all the profiles is the same. The first part of the study investigates the centred cases. Non-uniform stratification results in increasing wake turbulence relative to the benchmark owing to reduced suppression of turbulence production as well as wave trapping in the pycnocline. Steady lee waves are also quantified to understand the limitations of linear theory. The second part pays attention to the effect of a relative shift between the pycnocline and the disk. The wake defect velocity decays substantially faster in the cases with a shift and the wake has higher turbulence level. The effect of disk location on the Kelvin wake waves (a family of steady waves within the pycnocline) and its modal form is obtained and explained by solving the Taylor–Goldstein equation. The family of unsteady internal gravity waves that are generated by the wake is also studied and the effect of disk shift is quantified.

Computational study of free surface film flow and subsequent disintegration of a sheet and ligaments into droplets from a rotary disk atomizer

In the present study, a computational methodology based on computational fluid dynamics (CFD) is developed to investigate free surface film flow and its subsequent disintegration on a rotary disk atomizer. The present study provides an insight into efficiently modeling both liquid film formation and its subsequent disintegration. The presented computational methodology can easily be reproduced and can act as a benchmark for the modeling of liquid film formation as well as the disintegration phenomenon. The influence of disk speed, liquid flow and feed arrangement on the rotating disk are investigated. The film thickness profile on the disk resembles the formation of spiral waves at 500 RPM and an irregular breakup of the spiral waves for a disk speed of 1000 RPM. At higher speeds, a smooth and thin liquid film is observed on the disk. Offset feeding of the liquid on the disk alters the wave formation and breakup of the spiral waves. It is found that ligaments are formed at the lip of the disk owing to Rayleigh–Taylor instability, whereas liquid sheet breakup is due to combined rim and wave disintegration for the parameters investigated in this study.

Detailed analysis of the interference patterns measured in lab-based X-ray dual-phase grating interferometry through wave propagation simulation.

In this work, we analyze the interference patterns measured in lab-based dual-phase grating interferometry and for the first time explain the spatial dependencies of the measured interference patterns and the large visibility deviations between the theoretical prediction and the experimental results. To achieve this, a simulator based on wave propagation is developed. This work proves that the experimental results can be simulated with high accuracy by including the effective grating thickness profile induced by the cone-beam geometry, the measured detector response function and a non-ideal grating shape. With the comprehensive understanding of dual-phase grating interferometry, this provides the foundations for a more efficient and accurate algorithm to retrieve sample's structure information, and the realistic simulator is a useful tool for optimizing the set-up.

Estimation of the Thickness Profile of a Human Skull Phantom by Ultrasound Methods Using a Two-Dimensional Array

The paper presents the results of evaluating the thickness profile of a skull phantom using a two-dimensional ultrasound array consisting of piezoelectric elements with a center frequency of 2.1 MHz. Two pulse-echo ultrasound methods were used in the experiment: the A-mode elementwise measurements and scanning with a focused probing beam created by the entire array using delay-and-sum (DAS) beamforming. The obtained thickness profiles are compared with the reference thickness profile obtained using X-ray computed tomography. It was shown that ultrasound DAS beamforming with a focused probing beam makes it technically possible to estimate the thickness profile of the skull phantom.

Topography and Choroidal Thickness Measurement in Healthy Asian Indian Subjects using RTVue XR 100 Optical Coherence Tomography.

The purpose was to study the choroidal thickness and its profile, derived from different point locations in healthy Asian Indian subjects using RTVue XR 100 optical coherence tomography (OCT) and to determine its correlation with age, refractive error, and axial length. In this cross-sectional study, 300 eyes of 150 healthy subjects, with no ocular pathology, were scanned in a single session, using a line scan protocol of RTVue XR 100 OCT. Choroidal thickness was measured at the subfoveal region, and six measurements were obtained on either side of the fovea (temporal and nasal) at 500 μm interval apart, up to 3000 μm. The correlation between subfoveal choroidal thickness and age, refractive error, and axial length was assessed. Three hundred eyes of 150 healthy subjects were included in the analysis. Median age of the study participants was 55 years (interquartile range [IQR]: 44-61). The median subfoveal choroidal thickness was 235 μm (IQR: 210-263). The choroidal thickness was minimum at nasal 3000 μm from the fovea, while it was maximum in the subfoveal region. The point zones which were near the fovea showed thicker choroidal thickness than the outer zones, both nasally and temporally (P < 0.00001 at all locations), and at all point locations the choroid were thicker temporally than nasally (All P < 0.00001). Subfoveal choroidal thickness showed negative correlation with age (coefficient = -0.62, P = 0.03) and axial length (correlation = -8.52, P = 0.02). A decrease in subfoveal choroidal thickness of 0.62 μm/year was found by regression analysis. Our study provides normative database and topographic profile of choroidal thickness in the normal Asian Indian eyes using RTVue XR 100 OCT.

Interaction of bushes and aging coated pipes with complex profiles

The paper deals with the investigation of the interaction of a coated pipe and a system of rigid bushes when the profiles of the contacting surfaces are variable. For the posed problem, a mathematical model is written. Its solution is constructed on the basis of a special method that allows one to represent the functions related to the shapes of the contacting surfaces as separate terms in the final formulas for contact stresses. This representation of the solution allows for efficient and accurate calculations, even when the functions describing the coating thickness and bush profiles are rapidly changing.

Welding Characteristics of Laser-MIG Hybrid Welding of Arc-Welded Aluminum Profiles for High-Speed Trains.

To expand the application of laser-MIG hybrid welding in the arc-welded aluminum alloy profile manufacturing for high-speed trains, the laser-MIG hybrid welding characteristics of 4 mm thick A6N01S-T5 arc-welded aluminum profiles were studied in this work. The welding parameters were optimized using the orthogonal test; the microstructure and properties of the joints were analyzed. The results showed that the optimal welding parameters were: welding speed 1.0 m/min, laser power 2.7 kW, arc current 200 A, spot diameter 0.8 mm, heat source distance 3 mm, and defocusing amount 0 mm. The columnar crystals and dense dendrites were observed near the fusion line and in the weld center, respectively, and the grains in the heat-affected zone were slightly coarse. The microhardness of the softening zone in the heat-affected zone was the lowest. The average tensile strength of the joints was 212 MPa, about 86% of the base metal. The samples fractured in the heat-affected zone, and the fractures showed typical plastic fracture characteristics. The results showed that laser-MIG hybrid welding has good applicability and feasibility for the arc-welded profile welding manufacturing.

The Study of Carotid Artery Intima-Media Thickness in Children With Epilepsy on Anti-Epileptic Drugs.

Objectives. To evaluate carotid artery intima-media thickness (CIMT) and lipid profile in children with epilepsy on long-term antiepileptic drug (AED) monotherapy. Methods. We included 60 children with epilepsy receiving valproate, carbamazepine, or levetiracetam monotherapy and 60 controls. A high-resolution B-mode ultrasound was used to measure (CIMT). Measurement of serum lipids was done. Results. Patients on valproate (0.44 ± 0.03, P ≤ .001), carbamazepine (0.43 ± 0.03with P ≤ .001), and levetiracetam (0.44 ± 0.02 with P ≤ .001) monotherapy showed significantly higher CIMT compared to controls. CIMT was correlated with age (P = .041, r = .112) AEDs{valproate (P = .005, r = .731), carbamazepine (P = .038, r = .365), and levetiracetam (P = .036, r = .155)}, duration of treatment (P = .001, r = .313), TC(P = .001, r = .192), TG (P = .014, r = .018), and LDL (P = .001, r = .219). HDL (P = .003, r = -.126). Seizure severity and Apo A1 were insignificantly involved. Conclusion. Long-term monotherapy with valproate, carbamazepine, and levetiracetam in epileptic children was associated with significant abnormalities in CIMT.

The geoelectric approach to analyzing the profile of post-mining nickel laterite deposits in the Motui District, North Konawe Regency, Indonesia

The profile of laterite nickel deposits following mining operations can be determined using a geoelectric method, which is crucial information for exploration as well as sustainability. The purpose of this research is to ascertain the physical properties and thickness profile of laterite nickel deposits in the subsurface following mining. The geoelectric method used is resistivity to map variations in the apparent resistivity values of rocks. This value reflects the different types of rock layers in the subsurface. Through the use of two electrodes, an electric current was introduced into the earth, and the potential difference that resulted from this injection was then measured. Based on the configuration of the electrodes utilized, the apparent resistivity value can be determined. The profile of laterite nickel deposits in the Motui post-mining area includes three layers, red limonite, yellow limonite, and bedrock, with resistivity values ranging from 17.0 to 1572 Ωm. The resistivity of the red limonite layer ranges from 17.0 to 1572 Ωm, and its depth is 0 to 10 meters. The yellow limonite layer is between 10 and 20 meters thick and has a resistivity range of 17.0 to 31.8 m. The resistivity of bedrock, on the other hand, ranges from 84.2 to 1572 Ωm at depths between 20 and 70 meters.

Anterior segment optical coherence tomography analysis of regional epithelial thickness in keratoconus following intracorneal ring segment implantation

Background The changes in the epithelial thickness profile were found to be highly predictable and were responding to compensate for the changes in stromal curvature gradient. Aim The aim of this study was to evaluate the epithelial thickness after intracorneal ring segment (ICRS) implantation in patients with keratoconus and to correlate it with the uncorrected visual acuity (UCVA). Patients and methods This is a prospective nonrandomized clinical study that was conducted at the Faculty of Medicine, Ain Shams University, Cairo, Egypt. It included 24 eyes with keratoconus, which were implanted by ICRS and were scanned by CIRRUS HD-OCT 5000 preoperatively, at 1 week, 1 month, and 3 months postoperatively. The mean epithelial thickness (MET) at the cone and at the zone of ICRS implantation (5–7 mm) and UCVA were documented. Results The MET increased significantly from a preoperative value of 42.9±6.3–50.8±7.1 µm at 3 months postoperatively (P=0.01). In addition, the mean minimum (and not the mean maximum) epithelial thickness at the 5–7-mm zone increased significantly from 35.8±4.2 µm preoperatively to 38.7±5.4 µm at 3 months postoperatively (P=0.000). There was a statistically significant negative correlation between the MET and the mean UCVA preoperatively (r=−0.389, P=0.03), at 1 week (r=−0.415, P=0.04), and at 3 months postoperatively (r=−0.479, P=0.01). Conclusions The significant increase in the MET indicates the immediate, dynamic epithelial remodeling that continued up to 3 months after implantation. The increase in the minimum but not the maximum epithelial thickness confirms the epithelial remodeling rather than hyperplasia. The MET can be a prognostic factor for the visual outcome after ICRS as it correlated with the UCVA.

Profile thickness synthesis of thin-film waveguide Luneburg lens

In the work the link between the focusing inhomogeneity of the effective refractive index of waveguide Luneburg lens and the irregularity of the waveguide layer thickness generating this inhomogeneity is demonstrated. For the dispersion relation of irregular thin-film waveguide in the model of adiabatic waveguide modes the problem of mathematical synthesis and computer-aided design of the waveguide layer thickness profile for the Luneburg thin-film generalized waveguide lens with a given focal length is being solved. The calculations are carried out in normalized (in a special way) coordinates to adapt the used relations to computer calculations. The obtained solution is compared with the same solution within the cross-section’s method. The performance of the algorithm implemented in Delphi, was demonstrated by plotting the dispersion curves and plotting a family of dispersion curves, demonstrating a critical convergence. As an additional result, the thickness profiles of additional (irregular in thickness) waveguide layer, forming a thin film generalized waveguide Luneburg lens were synthesized. This result generalizes Southwell’s results.