Roll Patterns Research Articles

Revolutionizing iron texture analysis: the role of cold reduction and rolling directions through machine learning insights

ABSTRACT This study employs machine learning (ML) to analyze the melting and reconsolidation behaviors of iron, emphasizing the influence of cold reduction ratios and rolling sequences. Five samples with varied cold reduction ratios and rolling patterns were examined. Findings indicate that when the cold reduction ratio exceeds 65%, coordinated cold melting minimally impacts crystallographic consistency. Texture formation remains largely unaffected during cold melting and short-duration annealing. However, extended annealing prompts irregular grain growth, altering crystal orientation. Sheets rolled in alignment with their initial condition exhibit consistency patterns similar to conventionally cold-melted pure iron after prolonged annealing. Key parameters influencing material performance were evaluated, revealing annealing temperature as the most significant factor (5.94), followed by cold melting direction order (1.46), while the hanging period during annealing had minimal impact (1.02). ML models were employed to predict Goss angle expansion using cold-rolling and annealing parameters. This approach demonstrates the potential of ML to predict texture evolution in pure iron, offering valuable insights for optimizing industrial cold-rolling practices.

Rare case of low-grade fibro-myxoid sarcoma presenting as a lateral neck swelling

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon malignancy. LGFMS is more likely to affect the trunk and extremities in young adults. However, sporadic cases have been reported in many areas of the head and neck region, including the oral cavity, larynx, and oropharynx. LGFMS typically shows areas of collagenized, myxoid stroma with spindle cell appearance in a rolling pattern. Accurate diagnosis is challenging because it can be mistaken for a simple neoplastic entity of round cells. A few cases of LGFMS which have been reported in the head and neck showing that LGFMS is characterized by local recurrence and metastases. Because of the rarity of the head and neck region, there are no specific treatment guidelines or follow-up. Our study presents LGFMS in a 54-year-old patient in the neck region who underwent surgery and was followed up for one year.

Non-destructive compaction evaluation and comparison of different asphalt centerline longitudinal joints

Longitudinal joint quality is critical to the service life of asphalt pavements. Maintaining failed joints of asphalt pavements is a challenge for many highway agencies. Long-term performance issues of flexible pavements may result from a poorly constructed joint; the low-density joint can prematurely deteriorate an otherwise sound pavement. The longitudinal joint is built using different geometries, rolling patterns, and construction techniques, all involving risk in achieving a well-compacted joint. Conventional quality control (QC) and quality assurance (QA) testing (using cores or density gauges) provide limited coverage due to their spot-test nature. Using conventional QC/QA methods involves the risk of accepting a poorly constructed longitudinal joint at the time of construction. This study used continuous data from the non-destructive dielectric profiling system (DPS) to identify compaction ability differences between the various joint types and construction techniques. The analysis suggests avoiding constructing an unconfined joint when possible. Percent within limits (PWL) analysis shows that any joint geometry could produce minimal compaction differences between the joint and the mat. However, if an unconfined joint needs to be constructed, a portion of the unconfined joint should be cut back before paving the adjacent lane. Such a cutback technique can result in better unconfined joint compaction. Further, PWL results showed that using a smaller subsection/sublot can isolate local compaction issues; a 100 ft sublot length is preferable for PWL analysis when utilizing DPS for compaction evaluation.

Understanding the leaf rolling of paddy and exploring its management options under aerobic rice

Rice is a staple food in the diets of more than half of the world's population. With India's irregular rainfall patterns and continual environmental anomalies, particularly in Kerala, the identification of climate-smart management practices which can withstand drought is critical. In this context, atrial was conducted in the experimental plots to evolve effective water and nutrient management practices under aerobic rice in lateritic soils of Kerala. However, during the experiment in a few treatments, rolling of leaves was observed, and when explored for the reasons, it was due to soil moisture deficit and plant water stress. When compared to other crop species, rice is highly vulnerable to water deficit. In this regard, an attempt has been made to study the leaf rolling pattern in aerobic rice and how this can be managed with a few soil amendments so that rice productivity can be sustained. The results showed that plant growth parameters, relative water content (RWC), membrane leakage (ML) and spectral signatures were significantly affected by the leaf rolling. It was found that leaf rolling affected plants have less RWC and higher ML and are under drought stress. Pearson correlation analysis showed a strong positive correlation (P < 0.05) of key spectral indices with other physiological traits such as RWC and negatively correlated with ML. Moisture absorbent media such as cocopeat, compost, saw dust and vermiculite were attempted as management strategies to overcome this stress. Results showed that among the absorbents attmepted, cocopeat was found to be better in managing the stress. These results suggest that for aerobic rice under lateritic soil, moisture absorbent media such as cocopeat, has to be incorporated so that it can reduce the rate of leaf rolling thereby sustaining the paddy yield.

Evaluation of Thick-Lift Paving of Asphalt Concrete

This research paper focuses on the feasibility of thick-lift paving with asphalt concrete. Thick-lift paving is the placement of asphalt concrete in a lift greater than the allowable maximum by an agency, often four to five times the nominal maximum aggregate size. Thick-lift paving offers potential benefits including streamlining operations and eliminating the bond interface in multi-lift layers. However, it also presents challenges such as potential for inadequate compaction and lower ride quality. Asphalt concrete design and construction specifications from 19 state Departments of Transportation were reviewed. In the field, 28 thick-paving test sections were constructed with different lift thicknesses (3 to 10 in.), two mix designs, different paving screed settings, and different rolling patterns. All pavers were equipped with tamper bar screeds. During construction, the researchers monitored asphalt cooldown time and mat density. After construction, the ride quality of each section was measured, and cores were tested for air voids content. Acceptable mat compaction was achieved in all test sections, with additional roller passes having the most significant effect on compaction. The study also found that thick one-lift layers yielded better and more uniform compaction than two-lift layers. Thicker lifts had significantly longer cool down times and potentially increased roughness. Recommendations included the possible use of tamper bar screeds and additional roller passes to improve compaction. Scenarios that are suitable for thick-lift paving were identified.

Formation of convective roll patterns over a longitudinal throughflow in an active inhomogeneous porous medium with weak clogging

The convective stability of a plane-parallel longitudinal throughflow in a system consisting of two porous sublayers with distinct permeability is studied taking into account the weak pore clogging effect and given a finite difference in concentration between the upper and lower boundaries of the system. A system of differential equations for convection is derived within the framework of the continuum approach and the nonlinear MIM model. A linear stability analysis of the basic longitudinal flow is carried out. The boundary value problem is solved using the numerical technique for constructing a fundamental system of solutions. The neutral stability curves of the basic flow with respect to the disturbances in the form of rolls with different wavelength are obtained. For the absence of pore clogging, the convective stability maps of the critical solutal Rayleigh-Darcy number versus the permeability ratio for the initial uncontaminated sublayers, as well as the plots of the critical disturbance frequency and wave number versus the permeability ratio for some values of the Peclet number, are constructed. It is shown that these results have symmetry with respect to the solution for equal initial permeability of sublayers. The clogging effect associated with the solute adsorption and desorption in a porous medium is studied in the two-layered systems with the values 0.1 and 10 of the ratio of initial permeabilities of the sublayers; convection localization occurs in distinct sublayers. It was found that clogging increases the stability of the longitudinal basic flow relative to solutal inhomogeneity and breaks the symmetry of solutions with respect to the case when the two-layered system is reduced to a single layer with the same filtration properties of the porous medium throughout its volume. The influence of sorption effects on the critical parameters of oscillatory convection is investigated by plotting the critical solutal Rayleigh-Darcy number, disturbance frequency and wave number against the adsorption coefficient at fixed values of the desorption coefficient. The isolines of the stream function are constructed to analyze convective flow patterns. It was established that there is a weak relationship between the typical size of local convective roll patterns and the clogging parameters. It is shown that the sorption processes, which can lead to clogging, have a significant impact on the velocity of convective rolls moving along the two-layered system at a slight variation in their sizes.

Numerical study of porous tip treatment in suppressing tip clearance vortices in cavitating flow

Tip clearance cavitation (TCC) is a type of vortex cavitation. It widely exists in axial flow hydraulic machinery and has significant negative influence on the mechanical service life and the operating stability. It is necessary to suppress the tip clearance vortices (TCV) to control the TCC in engineering applications. Based on the analysis of the advantages and disadvantages of the present various suppression strategies, a new coupling method is proposed in this study by combining the damping approach and the diversion approach. Porous medium material is used to realize the coupling effect. A 2 mm span length porous tip is installed on the solid tip surface of a hydrofoil under two gap sizes conditions (representing two types of gap flow pattern), and excellent suppression results of the TCV and TCC are obtained. The characteristics and mechanism of the clearance flow are analyzed by numerical simulation. The numerical accuracy is verified by experimental qualitative observations. The simulation results show that the temporal and spatial stability of the clearance flow field is enhanced, and the leakage velocity and the TCV strength are weakened via the combined action of damping and diversion effects. There is a difference in the damping mechanism between the two gap flow patterns. It is a comprehensive result of viscous dissipation and momentum loss in the jet pattern represented by the small gap size, and primarily, the result of momentum loss in the rolling pattern represented by the large gap size.

Assessment and Intervention of Rolling Patterns for Symmetry in Athletes : Focused on Unilateral Sports

Assessment and Intervention of Rolling Patterns for Symmetry in Athletes : Focused on Unilateral Sports

Modification of the locomotor pattern when deviating from the characteristic heel-to-toe rolling pattern during walking.

Humans are amongst few animals that step first on the heel, and then roll on the ball of the foot and toes. While this heel-to-toe rolling pattern has been shown to render an energetic advantage during walking, the effect of different foot contact strategies, on the neuromuscular control of adult walking gaits has received less attention. We hypothesised that deviating from heel-to-toe rolling pattern affects the energy transduction and weight acceptance and re-propulsive phases in gait along with the modification of spinal motor activity. Ten subjects walked on a treadmill normally, then placed their feet flat on the ground at each step and finally walked on the balls of the feet. Our results show that when participants deviate from heel-to-toe rolling pattern strategy, the mechanical work increases on average 85% higher (F = 15.5; p < 0.001), mainly linked to a lack of propulsion at late stance. This modification of the mechanical power is related to a differential involvement of lumbar and sacral segment activation. Particularly, the delay between the major bursts of activation is on average 65% smaller, as compared to normal walking (F = 43.2; p < 0.001). Similar results are observable in walking plantigrade animals, but also at the onset of independent stepping in toddlers, where the heel-to-toe rolling pattern is not yet established. These indications seem to bring arguments to the fact that the rolling of the foot during human locomotion has evolved to optimise gait, following selective pressures from the evolution of bipedal posture.

Subharmonic instabilities in Kerr microcombs.

We report experimental observation of subharmonic mode excitation in primary Kerr optical frequency combs generated using crystalline whispering-gallery mode resonators. We show that the subcombs can be controlled and span a single or multiple free spectral ranges around the primary comb modes. In the spatial domain, the resulting multiscale combs correspond to an amplitude modulation of intracavity roll patterns. We perform a theoretical analysis based on eigenvalue decomposition that evidences the mechanism leading to the excitation of these combs.

Bilateral Sclerochoroidal Calcifications: A Case Report

Purpose: The aim of this case report is to describe a rare condition of bilateral sclerochoroidal calcification Case Report: A 79 years old asymptomatic Caucasian female was referred to our Ocular Oncology Center of the Ophthalmic Surgery Department of Pisa on November 2021. She was in apparent good health. Funduscopic examination revealed yellowwhite irregular lesions in the supero-temporal quadrant of both eyes. Best-corrected visual acuity was 20/20. B-scan and A-scan ultrasound revealed hyper-echoic solid lesions with acoustic orbital shadowing measuring 1.5 mm in thickness and 4.6 mm in diameter, on average. Enhanced Deep Imaging Optical Coherence Tomography showed a scleral lesion compatible with the presence of deposition of calcium with Table Mountain and rolling pattern. Fluorescein angiography revealed hypofluorescence in the arterial phase and a mild hyper-fluorescence in the venous phase with persistent late staining. Indocyanine green angiography showed hypo-fluorescence at the early, middle, and late phases. Systemic investigation of calcium and phosphate metabolism was performed and the patient didn’t display any underlying systemic disorder. Conclusion: It is important to know and recognize this condition. Although most cases of sclerochoroidal calcifications may be idiopathic, systemic laboratory workup must be performed to exclude calcium-phosphate metabolic disorder that can be associated to these ocular signs. Given the rare possible development of choroidal neovascularization, regular imaging checkup is recommended.

Пассивная конвективная вентиляция в двойном воздушно-пористом слое с внутренним тепловыделением, зависящим от доли твердой фазы

The convective stability of a two-layered system consisting of a heat-generating porous region underlying an air region has been numerically studied. The linear dependence of the heat release on the solid volume fraction is taken into account in the porous region. The equal constant temperature values are fixed on the external impermeable boundaries of the system. The critical internal Rayleigh-Darcy number at which the convection is induced in the system in the form of two-dimensional roll patterns with a given wave number has been determined. The convective flow is possible due to the formation of unstable density stratification in the presence of internal heat release. Two types of stationary convection, namely, the local and the large-scale convection, have been studied. The local flow arises in the air sublayer and scarcely penetrates into the porous sublayer. The large-scale convection covers both sublayers. The change in the convective regime occurs with the growth of one or another parameter of the system and indicates the variation of the instability type. It is accompanied by an abrupt (by times and tens of times) change in the critical wave number of roll patterns. Numerical calculations show a decrease in the onset value for both types of convection with increasing solid volume fraction ϕ in the porous sublayer and increasing relative thickness d of the air sublayer. The growth of the Darcy number (the dimensionless per-meability of the porous sublayer) also causes destabilization of the air motionless state at the given ϕ and d. The variation of the convection regime from a large-scale flow to a local one occurs with increasing relative thickness of the air sublayer, whereas an opposite transition from the local to the large-scale convection regime is observed with increasing Darcy number.

Modeling the contact interaction of leather with squeezing rollers

Mathematical models of the shape of roll contact curves and patterns of distribution of contact stresses in the roll module of a leather squeezing machine were developed. It was revealed that the shapes of the roll contact curves depend on the deformation and geometric parameters of leather and cloth, as well as the coefficient of friction between leather and rolls. It was established that normal stresses change from zero at the beginning and end of the roll contact zone to a maximum at the point of maximum deformation of leather located in the compression zone; shear stresses change their signs at the neutral point, which in the drive roll is located in the compression zone.

Effect of cooling rate on the microstructure and mechanical properties of high Ti-V microalloyed steel

High-strength low-alloy steels are known for their superior mechanical properties and these desired properties are achieved through controlled hot rolling. The cooling rate is one of the most important factors in controlled hot rolling, which plays a major role in the final microstructure and mechanical properties. In this work, the effect of the cooling rate on the final microstructure and mechanical properties of high Ti-V HSLA microalloyed steel was investigated using the Gleeble 1500™ thermomechanical processing simulator. The samples were cooled to room temperature after final pass deformation using two different cooling rates to simulate the 16 and 30 mm thick plate rolling patterns. Polygonal ferrite was found to be a dominant phase in the final microstructures; SEM-EBSD IPF maps also showed grains with random orientation distribution. Yield strength and ultimate tensile stress increased by approximately 14% and 10%, respectively, with increasing cooling rate.

Numerical study of free convection in a thin layer between coaxial horizontal cylinders

We consider free convection in 2D and 3D horizontal cylindrical layers with the inner hot and outer cold boundary at Ra (Rayleigh number) in range (4∙103 ÷ 4∙105) and the ratio δ ≈ 1:20 of the layer width to inner radius. Prandtl number was 0,71, fluid properties were taken for air at 293 K.It was shown that the flow in a 2D cylindrical layer can be divided into three regions. Stable symmetric convective rolls are formed in the layer’s upper part; regions with the transient flow appear at the lateral sides; transitional regions between the upper and the lateral regions have convective rolls of an unusual asymmetric shape.The flow in a 3D cylindrical layer in the upper part is organized into a spatially stable convective roll pattern. With increase of the Rayleigh number (Ra), roll pattern becomes suppressed by a transient plume pattern.The global Nu (the Nusselt number) is proportional to 0,0019∙Ra0,567 for the 2D case and to 0,22∙Ra0,192 for the 3D case. The 2D problem provides a reasonable estimation of the Nusselt number for Rayleigh number up to 4∙104 and overestimates Nu for higher Rayleigh number, which agrees with Lyapunov exponent values.

RF choke based methodology for flange effect mitigation and antenna isolation improvement in bistatic radars of aerospace vehicles

This paper presents a novel technique for mitigation of flange effect and antenna transmit to receive isolation improvement methodology using RF choke for the bistatic radars of aerospace vehicles. The presence of flange causes variation in antenna radiation pattern, by an increase in sidelobe level, decrease in gain and dip in roll pattern, thereby degradation in the performance of the antenna. An RF choke adjacent to the waveguide wall is introduced to nullify the undesirable effects of the flange. This Paper demonstrates through simulation and experimentation that this choke effectively suppresses the surface wave and can be applied in many types of antennas to improve the radiation pattern deteriorated by parasitic elements. It is also demonstrated through measurements that the isolation from transmit to receive antenna is improved by introducing choke, with this technique antenna isolation is enhanced by 23 dB with 11 dB antenna gain. The gain and sidelobe improvement of the antenna with RF choke is 2 dB, and 6 dB, respectively. The proposed array antenna is fabricated with and without choke, measurements are performed and test results are presented. The isolation test between transmit & receive antenna is performed in an anechoic chamber and test results are presented.

Investigation of the secondary flow by convergent–divergent riblets in a supersonic turbulent boundary layer over a compression ramp

In this paper, the effect of the secondary flow induced by convergent–divergent riblets in supersonic turbulent boundary layers over a 24° compression ramp at Mach number 2.9 is studied via direct numerical simulation. Two riblet cases with the wavelength Λ being 1.1δ and 1.65δ (δ is the boundary layer thickness) are conducted to examine their impact on the secondary rolling motion, momentum transfer, turbulent fluctuations, flow separation, and unsteady shock motion. As the flow develops over the riblet section, both the size and intensity of the secondary rolling motion tend to increase. For the riblet case with Λ/δ=1.1, a single rolling mode is observed within a half wavelength, while a pair of co-rotating vortical structures is obtained for Λ/δ=1.65. Both rolling patterns lead to an apparent spanwise variation of the flow field. The results reveal that the secondary flow contributes to the increase of both the mean momentum flux and turbulent fluctuations. By using the spanwise averaging, the mean momentum flux contributed from the dispersive stress and compressible effect caused by the secondary flow is identified. Both components appear to enhance the near-wall momentum mixing, and a larger enhancement is observed for Λ/δ=1.1, where the intensity of the secondary flow is stronger. Compared to the baseline case, the area of the separation zone at Λ/δ=1.1 and Λ/δ=1.65 is decreased by 56% and 38%, respectively. For all the cases, the low-frequency motion near the foot of the shock is observed. In comparison, the frequency of the low-frequency motion for the riblet case is two times higher than that in the baseline case, owing to the reduction of the separation area and length.

Effect of bubble size on the rising behavior in pure water medium

The phenomenon of rising bubbles in pure water is an important aspect of the bubble and liquid interactions. Due to several forces that act on the bubble accompanied by the pressures inside and outside the bubble, the rising bubble behaviour may vary depending on a few parameters such as the characteristics of the bubble and liquid medium. In general, the bubble increase occurs following the drag motion determined by the bubble drag coefficient but under certain conditions bubble also may move by a rolling pattern. Both drag and rolling are related to other forces that worked on the bubble, particularly the buoyancy force. The velocity of them may be different due to the mechanism types of motions. Rolling motion can be assumed does not occur for a very small bubble so there is only a relation between size and velocity. Several observations of bubble sizes have shown that for a very small bubble there is a linear relationship between size and rising velocity. Meanwhile, for a larger bubble, the rising velocity becomes faster almost seems an exponential relation. The increase of the bubble size results in a higher buoyancy force so that the bubbles rise more easily to reach the water surface. This paper aimed to prove that the small bubble will show linear relation of the rising velocity depending on the size. Our experimental observation has shown that the linearity of velocity only occurred for a very small bubble. This linearity gradient becomes quite important for predicting the rising pattern of other various bubble sizes.

The effect of rolling process on the mechanical and electrical properties of CNTs-enhanced GFRP

In this paper, the mechanical properties of glass fiber reinforced plastic (GFRP) laminates are enhanced by improving the preparation process and toughening with the nano-fillers. The carbon nanotubes (CNTs) solution was prepared and sprayed into GFRP laminates as an interlaminar enhancement layer. To explore the effect of different rolling reduction rates (1.5%, 3%, 6%) and different rolling patterns (cold rolling and hot rolling) on CNTs-enhanced GFRP, the three-point bending test, the end-notch flexure (ENF) test, and the tensile test were designed and carried out. Results revealed that the optimal rolling reduction rate was 3%, and the mechanical properties of GFRP laminates enhanced by the hot rolling process were found to be relatively superior to the cold rolling process. Simultaneously, the CNTs interlayer could significantly improve the mechanical properties of GFRP, i.e., flexural strength, mode II interlaminar fracture toughness and tensile strength enhancing with 69%, 56% and 50%, respectively. The results of the Scanning Electron Microscope (SEM) exhibited that the hot rolling pressure could accelerate the mutual diffusion of the resin and CNTs, effectively forming a fiber/resin/CNTs strengthening interface. In addition, the rolling process could cause the partial disconnection of conductive network paths of CNTs film, resulting in an increase of the resistance change rate.

A Manta Ray Robot with Soft Material Based Flapping Wing

Recent research on robotic fish mainly focused on the bionic structure design and realizing the movement with smart materials. Although many robotic fish have been proposed, most of these works were oriented toward shallow water environments and are mostly built with purely rigid structures, limiting the mobility and practical usability of robotic fish. Inspired by the stability of the real manta ray, a manta ray robot design is proposed with soft material made flapping wing based on an open-source ROV (Remotely Operated Vehicle). The flapping wing structure with three different materials mimics the wide pectoral fins of real manta rays, which have bones, muscles, and skin. Furthermore, its modular design makes it easy to install and disassemble. The kinematic and hydrodynamic analysis of the manta ray robot are simulated in this paper. The actual manta ray robot is fabricated and several sets of test are performed in the pool. The robot can swim forward continually and stably with a simple rolling and pitching pattern.