Thickness Profile Research Articles

Closed-loop thickness control and sensor placement in extrusion blow moulding

Extrusion blow moulding (EBM) is a polymer forming technique used to manufacture hollow plastic parts, such as fuel tanks. In this work, the feasibility of using closed-loop control in EBM is explored to compensate for machine drift and disturbances. A control system is proposed to regulate the extrusion process in EBM. The extrusion controller aims to increase process consistency by minimizing part thickness deviations. The thickness of the extrudate is measured during the extrusion cycle and any deviation from the desired thickness profile is compensated by changing the die gap in real time. The controller, which offers flexibility in thickness sensor placement, features a Smith predictor configuration embedding an H∞ controller. It compensates for the input-dependent polymer transport delay, the nonlinear steady-state swell, and nonminimum phase necking effects affecting the extrudate. This extrusion control technique may help reduce the production rate of off-specification parts and improve product quality.

Influence of Thickness Profile after Sizing Press on Width Profile at Head and Tail Portions of Slab

Influence of Thickness Profile after Sizing Press on Width Profile at Head and Tail Portions of Slab

Integrated self-referencing single shot digital holographic microscope and optical tweezer

Digital holographic microscopy is a single-shot technique for quantitative phase imaging of samples, yielding thickness profiles of phase objects. It provides sample features based on their morphology, leading to their classification and identification. However, observing samples, especially cells, in fluids using holographic microscopes is difficult without immobilizing the object. Optical tweezers can be used for sample immobilization in fluids. The present manuscript provides an overview of our ongoing work on the development of a compact, low-cost microscopy system for digital holographic imaging of optically trapped samples. Integration of digital holographic microscopy system with tweezers is realized by using the optical pickup unit extracted from DVD burners to trap microsamples, which are then holographically imaged using a highly compact self-referencing interferometer along with a low-cost, in-house developed quadrant photodiode, providing morphological and spectral information of trapped particles. The developed integrated module was tested using polystyrene microspheres as well as human erythrocytes. The investigated system offers a multitude of sample features, including physical and mechanical parameters and corner frequency information of the sample. These features were used for sample classification. The proposed technique has vast potential in opening up new avenues for low-cost, digital holographic imaging and analysis of immobilized samples in fluids and their classification.

Is there any connection between choroidal thickness and obesity?

Obesity is a health-threatening and epidemic medical condition that can affect individuals of different ages and is potentially associated with an increased risk of systemic and ocular disorders. Despite the well-documented adverse effects of obesity on different parts of the body vasculature, less published data are available concerning obesity-related consequences on the ocular vasculature. As the human choroid is a highly vascularized tissue, its morphology and function might be altered in obese individuals. The micro-structural changes within the choroid could also trigger development of subsequent functional abnormalities of the eye. Previous population-based studies have asserted an association between obesity and choroidal thickness; however, they reported conflicting patterns of association between obesity and changes in choroidal thickness. Therefore, to enhance our understanding of the changes in choroidal morphology secondary to obesity, we reviewed studies describing the micro-structural consequences of obesity on the choroidal thickness profile and its underlying physiological and anatomical basis. This review includes all original publications related to the association between choroidal thickness and obesity published until mid-2021 that were indexed in PubMed, Google Scholar, ScienceDirect, or Scopus.

Applications of epithelial thickness mapping in corneal refractive surgery.

In this review, we discuss the applications of epithelial thickness mapping in corneal refractive surgery. The review describes that the epithelial thickness profile is nonuniform in the normal eye, being thinner superiorly than inferiorly and thinner temporally than nasally. It is postulated that this is due to the eyelid forces and blinking action on the superior cornea. Changes in the epithelial thickness profile have been found to be highly predictable, responding to compensate for changes in the stromal curvature gradient, using the eyelid as an outer template. This leads to characteristic changes in the epithelial thickness profile that can be used for early screening in keratoconus, postoperative monitoring for early signs of corneal ectasia, and for determining whether further steepening can be performed without the risk of apical syndrome following primary hyperopic treatment. Compensatory epithelial thickness changes are also a critical part of diagnosis in irregular astigmatism as these partially mask the stromal surface irregularities. The epithelial thickness map can then be used to plan a trans-epithelial photorefractive keratectomy treatment for cases of irregularly irregular astigmatism.

Comparative Analysis of In vitro Quality Parameters of Different Brands of Marketed Ciprofloxacin Tablets Available in Bangladesh

Aim: Ciprofloxacin is a broad‑spectrum antibiotic under the group of drugs called fluoroquinolones. It is extensively being manufactured and marketed drug by many national and multinational pharmaceutical companies. The purpose of this study was to compare the quality of different brands of ciprofloxacin 500mg tablets available in Bangladesh using quality characteristics such as weight variation, hardness, thickness, friability, disintegration time, and dissolution profile.
 Methodology: The tablets' overall quality criteria, such as weight variation, hardness, thickness, diameter, friability, disintegration time, and dissolving profile, were evaluated using established protocols. An electric analytical balance was employed to measure weight variation. An automated hardness tester was used to determine the hardness, thickness, and diameter. A friabilator was used to determine the degree of friability. A disintegration equipment and a dissolution tester were used to examine the disintegration time and dissolution profile, respectively.
 Results: In this study, all the values were compared with the standards. All brands had been passed for the weight variation test, because no tablets surpass the ± 5 % weight variation. The weight variation range was from 714.57±4.08 mg (brand C) to 837.92±7.49 mg (brand E). In hardness testing procedure, all brands of ciprofloxacin 500mg tablets were within the specified limit. The average hardness of the items ranges from 11.11±1.44 kgF to 19.26±2.20 kgF respectively. The five brand's percentage friability was less than 1%, indicating that they met the requirements. The lowest friability (0.015 %) was found in Brand E, while the highest friability (0.032 %) was found in Brand B. Within 10 minutes, the entire trademark had disintegrated, indicating that they had met the requirements. Brand E had the quickest disintegration time (5.35±0.49 minutes), while brand B had the slowest (9.12±0.88 minutes).All brands had a dissolution rate of 83.56% for A, 95.84% for B, 91.15% for C, 84.46% for D and 88.97% for E, all those were within 60 minutes in dissolution testing. The five brands' assay was within the specified limit, indicating that they met the requirements
 Conclusion: In conclusion, the present study of evaluating quality control parameters revealed that all of the leading brands of this tablet comply the quality control parameters as per pharmacopoeial specifications. Further work is recommended on bioequivalence of these tablets.

Iterative tomography of pipes during operation

The pipe wall thickness was estimated based on three-dimensional images of the pipe recovered from several X-ray projections, which were made in a limited angle of view. Since the effects of scattered radiation and beam hardening are up to 50 % of the main radiation, ignoring them leads to blur of the image and inaccuracy in determining dimensions. To restore pipe images from projections, a volume and/or shell representation of the pipe is used, as well as iterative Bayesian methods. Using these methods, the error in estimating the pipe wall thickness from the projection data can be equal to or less than 300 μm. It has been shown that standard X-ray projections on the film or imaging plates used to obtain data can be used to restore pipe wall thickness profiles in factory conditions.

Tailored Magnetic Linear Birefringence in Wedge-Shaped Co Nanocluster Assemblies

The purpose of this paper is to present an experimental method to induce strong magnetic linear birefringence in two-dimensional assemblies of Co nanoclusters grown on glass plates. Additionally, we have also correlated the magnitude and characteristics of that nonlinear magneto-optical effect with the thickness and profile of those disordered nanostructures. For those aims, we have grown Co nanocluster assemblies on amorphous substrates, by means of pulsed laser ablation in off-axis geometry. This approach enabled us to obtain magnetic media with an intended and pronounced thickness profile, i.e., wedge-shaped assembly, to investigate the orientation and behavior of surface magnetization regarding both the thickness gradient direction and in-plane magnetic field. That study was accomplished by measuring the magneto-optical effects in reflection and transmission configurations, unveiling an out-of-plane magnetization whose magnitude depends closely on the thickness gradient direction. That component, arising from a graded magnetic anisotropy along the wedged nanostructure, adds a reversal mechanism to the surface magnetization, thus being responsible for the magnetic linear birefringence in our ultrathin Co assemblies.

Joining of hybrid semi-finished products from sheet metal by orbital forming

Contrary demands like a reduction of carbon dioxide emissions and an increase in functionality are facing the manufacturing industry with growing challenges. When processing functional components, like synchronizer rings, conventional process chains, like shearing and subsequent joining, are reaching their limits due to an increased complexity of the components and a lack in efficiency, referring to the long process time. To meet these challenges, the strategy of lightweight construction combines the application of lightweight materials with efficient manufacturing processes and an innovative product design. One possibility within lightweight construction is the utilization of load-adapted hybrid components, featuring different material strength classes. In previous research, the process of orbital forming is used to manufacture semi-finished products with a varying thickness profile due to the specific radial material flow. This material flow should now be used to realize a permanent joint between materials of two different strength levels. Therefore, the process of orbital forming is modified to manufacture hybrid semi-finished products from a dual-phase steel DP600 and a naturally rigid aluminum alloy EN AW 5754, both with an initial thickness of 2.0 mm. Different joint geometries are cut by laser into a steel ring and the part is coaxially positioned around a basic aluminum disc inside a die and subsequently formed. The joint is investigated regarding the geometrical and mechanical properties, comparing a radial cross-section and the micro hardness distribution. In order to reveal the potential of orbital forming for a combined forming and joining operation, the axial as well as the peeling strength of the multi-material components are investigated and evaluated.

Efficient Three-Dimensional Model to Predict Time History of Structural Dynamics in Cold Rolling Mills

Abstract Introduced is a new physics-based three-dimensional (3D) mathematical model capable of efficiently predicting time histories of the nonlinear structural dynamics in cold rolling mills used to manufacture metal strips and sheets. The described model allows for the prediction of transient strip thickness profiles, contact force distributions, and roll-stack deformations due to dynamic disturbances. Formulation of the new 3D model is achieved through a combination of the highly efficient simplified-mixed finite element method with a Newmark-beta direct time integration approach to solve the system of differential equations that governs the motion of the roll-stack. In contrast to prior approaches to predict structural dynamics in cold rolling, the presented method abandons several simplifying assumptions and restrictions, including 1D or 2D linear lumped parameter analyses, vertical symmetry, continuous and constant contact between the rolls and strip, as well as the inability to model cluster-type mill configurations and accommodate typical profile/flatness control mechanisms used in industry. Following spatial and temporal convergence studies of the undamped step response, and validation of the damped step response, the new model is demonstrated for a 4-high mill equipped with both work-roll bending and work-roll crown, a 6-high mill with continuously variable crown (CVC) intermediate rolls, and finally a complex 20-high cluster mill. Solution times on a single computing processor for the damped 4-high and 20-high case studies are just 0.37 s and 3.38 s per time-step, respectively.

Diagnosis of bipolar disorders and body mass index predict clustering based on similarities in cortical thickness-ENIGMA study in 2436 individuals.

Rates of obesity have reached epidemic proportions, especially among people with psychiatric disorders. While the effects of obesity on the brain are of major interest in medicine, they remain markedly under-researched in psychiatry. We obtained body mass index (BMI) and magnetic resonance imaging-derived regional cortical thickness, surface area from 836 bipolar disorders (BD) and 1600 control individuals from 14sites within the ENIGMA-BD Working Group. We identified regionally specific profiles of cortical thickness using K-means clustering and studied clinical characteristics associated with individual cortical profiles. We detected two clusters based on similarities among participants in cortical thickness. The lower thickness cluster (46.8% of the sample) showed thinner cortex, especially in the frontal and temporal lobes and was associated with diagnosis of BD, higher BMI, and older age. BD individuals in the low thickness cluster were more likely to have the diagnosis of bipolar disorder I and less likely to be treated with lithium. In contrast, clustering based on similarities in the cortical surface area was unrelated to BD or BMI and only tracked age and sex. We provide evidence that both BD and obesity are associated with similar alterations in cortical thickness, but not surface area. The fact that obesity increased the chance of having low cortical thickness could explain differences in cortical measures among people with BD. The thinner cortex in individuals with higher BMI, which was additive and similar to the BD-associated alterations, may suggest that treating obesity could lower the extent of cortical thinning in BD.

Thickness gradient related magnetic anisotropy of wedged Co nanocluster assemblies deposited on glass plates

We prove the existence of uniaxial magnetic anisotropy (UMA) directly related to thickness gradients in a material system comprised of planar assemblies of Co nanoclusters (diameter∼2.5 nm), grown by pulsed laser deposition (PLD) on bare glass substrates. PLD provides a widespread coating that takes place with a decreasing thickness along the radial directions of a glass plate faced perpendicular to the ablation jet, yielding a wedge-like shape of the film thickness profile. Reflection and transmission magneto-optical effects enabled us to study magnetization vector as a function of the film thickness and location, revealing in-plane magnetization with a well-defined UMA along the in-plane direction parallel to the thickness gradient only in high-gradient films. The dependence of anisotropy energy on film thickness has been analyzed within a phenomenological model, accounting for the surface and bulk contributions to the effective magnetic anisotropy energy (MAE). According to that, below a threshold thickness, the volume contribution is low and Nèel-like interface contribution to MAE is negligible, as well as the null magneto-crystalline contributions of such a disorder cluster system, leaving only potential surface terms left. MAE is thus tentatively explained with the extra cluster terraces related to high-gradient thickness. Additionally, the magnetization along the in-plane hard axis or thickness gradient direction (TGD) includes a minor out-of-plane component noticed as a Faraday rotation in transmission geometry. We speculate it may arise from geometrical frustration of moments occurred in the hard axis magnetization of the network of interconnected assemblies.

A 2.5D miniaturized low-profile ultra-wideband band-stop frequency selective surface

This paper proposes a miniaturized UWB band-stop frequency selection surface based on metalized via technology, aiming at the problem of the large cell size and thick profile of the UWB band-stop frequency selection surface. By studying the principle of miniaturization of 2.5D frequency selective surface, a 2.5D ultra-wideband band-stop miniaturized frequency selective surface with high angular stability and low profile is designed. The simulation and test results show that the designed structure can cover the ultra-wideband frequency range of 2.36 GHz ∼ 11.36 GHz, the −10 dB percentage bandwidth is 161.9%, the unit size is , and the thickness is , where represents the resonance wavelength in free space. The maximum incident angle can reach 60 degrees for TE and TM polarization. Compared with the existing literature, the designed ultra-wideband band-stop miniaturization frequency selection surface miniaturization is better, and the profile is lower.

A new approach for quantifying epithelial and stromal thickness changes after orthokeratology contact lens wear.

The aim of the study was to develop an automatic segmentation approach to optical coherence tomography (OCT) images and to investigate the changes in epithelial and stromal thickness profile and radius of curvature after the use of orthokeratology (Ortho-K) contact lenses. A total of 45 right eyes from 52 participants were monitored before, and after one month of, uninterrupted overnight Ortho-K lens wear. The tomography of their right eyes was obtained using optical OCT and rotating Scheimpflug imaging (OCULUS Pentacam). A custom-built MATLAB code for automatic segmentation of corneal OCT images was created and used to assess changes in epithelial thickness, stromal thickness, corneal and stromal profiles and radii of curvature before, and after one month of, uninterrupted overnight wear of Ortho-K lenses. In the central area (0–2 mm diameter), the epithelium thinned by 12.8 ± 6.0 µm (23.8% on average, p < 0.01) after one month of Ortho-K lens wear. In the paracentral area (2–5 mm diameter), the epithelium thinned nasally and temporally (by 2.4 ± 5.9 µm, 4.5% on average, p = 0.031). The stroma thickness increased in the central area (by 4.8 ± 16.1 µm, p = 0.005). The radius of curvature of the central corneal anterior surface increased by 0.24 ± 0.26 mm (3.1%, p < 0.01) along the horizontal meridian and by 0.34 ± 0.18 mm (4.2%, p < 0.01) along the vertical meridian. There were no significant changes in the anterior and posterior stromal radius of curvature. This study introduced a new method to automatically detect the anterior corneal surface, the epithelial posterior surface and the posterior corneal surface in OCT scans. Overnight wear of Ortho-K lenses caused thinning of the central corneal epithelium. The anterior corneal surface became flattered while the anterior and posterior surfaces of the stroma did not undergo significant changes. The results are consistent with the changes reported in previous studies. The reduction in myopic refractive error caused by Ortho-K lens wear was mainly due to changes in corneal epithelium thickness profile.

Formulation and evaluation of controlled release ocusert of gatifloxacin and prednisolone

Abstract Objective: Ocuserts are sterile, solid, or semisolid dosage forms prepared to attain increased contact time between the drug and the conjunctival tissue to keep up a constant release of drug when placed in the lower cul-de-sac or conjunctival sac of the eye. The aim of formulating this delivery system was to treat both inflammatory and infectious conditions of the eye with increased ocular residence time by releasing drugs at a slow and constant rate. Method: Gatifloxacin, and prednisolone ocuserts were prepared by solvent casting method, and evaluated for physical appearance, uniformity of weight, thickness, folding endurance, drug content, surface pH, in-vitro, and ex-vivo release profile. Results: All formulated inserts exhibited positive results in terms of their evaluation parameters. Ocuserts were sterile, with no turbidity in selected media during the study, and they were stable throughout six months. Conclusion: Results suggested that prepared optimized ocusert formulation would be a suitable alternative to eye drops for treating conjunctivitis and other bacterial infections.

Mechanical properties and fatigue of extruded D16 alloy profiles of the Al-Cu-Mg system after ion irradiation

The effect of 20-keV Ar+ ion irradiation on the mechanical properties andfatigue resistance of 6 mm thick hot-extruded profiles made of a D16 alloy (Al–Cu–Mg system) has been studied after natural aging. Irradiation at fluences of 2.1015 cm−2 and 1.1016 cm−2 has been revealed to increase the number of cycles to failure significantly at low load amplitudes σ/σu = 0.3. The maximum increase in the number of cycles to destruction 2.4 times is observed at a smaller fluence of ions F = 2.1015 cm−2.

Phase structure and its temporal evolution under growing single vapor bubble

A vapor bubble's footprint on a heated surface is composed of dry and wet regions, and their temporal evolution is governed by several forces, such as gravity, vapor inertia, viscous friction, and capillarity. In this Letter, we derive three types of relations that depict the dynamic variations in the length scales for the bubble base, dry area, and thin liquid film under a single vapor bubble. The proposed relations are validated using measurement results from clear images of the phase structure captured by high-speed visualization. Here, we reveal that the viscous friction is a dominant force acting on the bubble expansion process; however, it has been previously ignored for simplicity in dealing with the classical Rayleigh equation. Additionally, the critical role of the liquid wetting character in the vicinity of the moving triple phase line is illuminated to quantify the dry area dynamics. Finally, we find an analytic expression to obtain the thickness profile of the thin liquid film under a bubble based on the well-known Landau and Levich liquid coating theory.

Retinal Nerve Fiber Layer Thickness and Rim Area Profiles in Asians: Pooled Analysis from the Asian Eye Epidemiology Consortium

To evaluate ethnic variations, ocular and systemic determinants of retinal nerve fiber layer (RNFL) thickness, and neuroretinal rim area among Asians using a large consortium of population-based eye studies. Cross-sectional pooled analysis. Twenty-two thousand four hundred thirty-six participants (22 436 eyes) from 10 population-based studies (in China, Hong Kong, India, Japan, Russia, and Singapore) of the Asian Eye Epidemiology Consortium. Participants 40 years of age or older without glaucoma were included. All participants underwent spectral-domain OCT imaging and systemic and ocular examinations. Data were pooled from each study. Multivariable regression was performed to evaluate interethnic differences, intermachine variations, and ocular and systemic factors associated with RNFL thickness and rim area, adjusting for age, gender, diabetes, intraocular pressure (IOP), spherical equivalent (SE), ethnicity, OCT model, and study group. When evaluating body mass index, smoking, and hypertension as exposures, these factors were additionally adjusted for in the model. Average RNFL thickness (in micrometers) and rim area (in square millimeters). Indian and Japanese eyes have thinner RNFLs than those of other Asian ethnicities (β values range, 7.31-12.76 μm; P < 0.001 for all pairwise comparisons). Compared with measurements by Cirrus HD-OCT (Carl Zeiss Meditec, Inc), RNFL on average was 7.29 μm thicker when measured by Spectralis (Heidelberg Engineering), 12.85 μm thicker when measured by RS-3000 (NIDEK Co, Ltd), and 17.48 μm thicker when measured by iVue/RTVue (Optovue, Inc) devices (all P < 0.001). Additionally, older age (per decade, β= -2.70), diabetes (β= -0.72), higher IOP (per 1 mmHg, β= -0.07), more myopic SE (per diopter, β= -1.13), cardiovascular disease (β=-0.94), and hypertension (β= -0.68) were associated with thinner RNFL (all P ≤ 0.003). Similarly, older age (β= -0.019), higher IOP (β= -0.010), and more myopic SE (β= -0.025) were associated with smaller rim area (all P < 0.001). In this large pooled analysis of Asian population studies, Indian and Japanese eyes were observed to have thinner RNFL profiles. These findings suggest the need for an ethnic-specific normative database to improve glaucoma detection.

Microlayer dynamics during the growth process of a single vapour bubble under subcooled flow boiling conditions

The phenomena of microlayer formation and its dynamic characteristics during the nucleate pool boiling regime have been widely investigated in the past. However, experimental works on real-time microlayer dynamics during nucleate flow boiling conditions are highly scarce. The present work is an attempt to address this lacuna and is concerned with developing a fundamental understanding of microlayer dynamics during the growth process of a single vapour bubble under nucleate flow boiling conditions. Boiling experiments have been conducted under subcooled conditions in a vertical rectangular channel with water as the working fluid. Thin-film interferometry combined with high-speed cinematography have been adopted to simultaneously capture the dynamic behaviour of the microlayer along with the bubble growth process. Transients associated with the microlayer have been recorded in the form of interferometric fringe patterns, which clearly reveal the evolution of the microlayer beneath the growing vapour bubble, the movement of the triple contact line and the growth of the dryspot region during the bubble growth process. While symmetric growth of the microlayer was confirmed in the early growth phase, the bulk flow-induced bubble deformation rendered asymmetry to its profile during the later stages of the bubble growth process. The recorded fringe patterns have been quantitatively analysed to obtain microlayer thickness profiles at different stages of the bubble growth process. ForRe = 3600, the maximum thickness of the almost wedge-shaped microlayer was obtained asδ ~ 3.5 μm for a vapour bubble of diameter 1.6 mm. Similarly, forRe = 6000, a maximum microlayer thickness ofδ ~ 2.5 μm was obtained for a bubble of diameter 1.1 mm.

Aerogeophysical systematics applied to the geological reconnaissance of the Eastern Pernambuco-Alagoas Domain, Borborema Province: The Ipojuca-Atalaia Batholith

Over the past few decades, geological and geophysical studies in the Borborema Province (NE Brazil) have evolved considerably, especially in the North and Central subprovinces. However, the Pernambuco-Alagoas Domain, inserted in the South subprovince, does not have, up to now, detailed geophysical and geological studies, mainly due to a thick soil profile, which make difficulty the geological survey in the region. The aerogeophysical study of an area located in the Ipojuca-Atalaia Batholith, Eastern part of the Pernambuco-Alagoas Domain allowed the delimitation of the lithogeophysical and magnetic geophysical domains, main directions of the lineaments, main shear zones, and their behavior in depth through the upward continuation and the Euler Deconvolution. The set of integrated magnetometric data revealed that the region was intensely deformed by a set of transcurrent shear zones of NE-SW direction. Aerogammaspectrometric data enabled the improvement of the geological mapping (1) of the Western part of the Ipojuca-Atalaia Batholith granitic plutons and gneisses and (2) of the limits of the batholith with the adjoining crustal sub-domains. The integration of the whole set of aero magnetometric and aero gammaspectrometric data also provides a basis for a better understanding of the tectonic evolution of the studied area and the Ipojuca-Atalaia Batholith.