Single Roll Research Articles

Comparison of A Single Vibration Foam Rolling and Static Stretching Exercise on the Muscle Function and Mechanical Properties of the Hamstring Muscles.

Knee extension and hip flexion range of motion (ROM) and functional performance of the hamstrings are of great importance in many sports. The aim of this study was to investigate if static stretching (SS) or vibration foam rolling (VFR) induce greater changes in ROM, functional performance, and stiffness of the hamstring muscles. Twenty-five male volunteers were tested on two appointments and were randomly assigned either to a 2 min bout of SS or VFR. ROM, counter movement jump (CMJ) height, maximum voluntary isometric contraction (MVIC) peak torque, passive resistive torque (PRT), and shear modulus of semitendinosus (ST), semimembranosus (SM), and biceps femoris (BFlh), were assessed before and after the intervention. In both groups ROM increased (SS = 7.7%, P < 0.01; VFR = 8.8%, P < 0.01). The MVIC values decreased after SS (-5.1%, P < 0.01) only. Shear modulus of the ST changed for -6.7% in both groups (VFR: P < 0.01; SS: P < 0.01). Shear modulus decreased in SM after VFR (-6.5%; P = 0.03) and no changes were observed in the BFlh in any group (VFR = -1%; SS = -2.9%). PRT and CMJ values did not change following any interventions. Our findings suggest that VFR might be a favorable warm-up routine if the goal is to acutely increase ROM without compromising functional performance.

Effects of B Addition on the Microstructure and Microhardness of Melt-Spun Al-7075 Alloy

Abstract Main aim of this study is to examine change of microstructural and the mechanical properties of Al-7075 alloy depending on B content added with different proportions. Rapid solidification process used to produce the alloys was carried out with a single roll melt spinner via a wheel with a rotational speed of 25 m/s. For the microstructural characterization of the alloys, a scanning electron microscope and X-ray diffraction analyzes were used. According to obtained results, it can be said that B addition led to modification of dimensions and shapes of both α−Al and intermetallic phases occurred, it reduced average grain size from 0.45 μm to 0.34 μm in the microstructure. The B addition also led to dramatically increase in microhardness of the Al-7075 alloy. The microhardness of the alloy with 0.4 wt. % B is 0.19 GPa, this is clearly one times higher than that of the alloy without B addition. The microhardness of the alloy with 1 wt. % B is 0.21 GPa, this is also slightly higher than that of the alloy with 0.4 wt. % B.

Comparative analysis between single flank rolling test for micro gears and analytical simulation of optical measurements

Abstract This approach analyses the differences between a single flank rolling test and an analytical simulation based on optical measurement data of micro gears. The focus is on a signal-based comparison of the rolling behaviour. Using methods in the time and frequency domain as well as the derivation of methods such as cross-correlation, the capability of this simulative approach is qualified. Due to short measurement times with high correlations to the test rig, an inline integration of this analytical simulation for quality assurance of micro gears in series production will be implemented as part of a holistic approach.

Prepare for Ludicrous Speed: Marker-based Instantaneous Binocular Rolling Shutter Localization.

We propose a marker-based geometric framework for the high-frequency absolute 3D pose estimation of a binocular camera system by using the data captured during the exposure of a single rolling shutter scanline. In contrast to existing approaches enforcing temporal or motion models among scanlines (e.g. linear motion, constant velocity or small motion assumptions), we strive to determine the pose from instantaneous binocular capture (i.e. without using data from previous scanlines) and achieve drift-free pose estimation. We leverage the projective invariants of a novel rigid planar pattern, to both define a geometric reference as well as to determine 2D-3D correspondences from raw edge detection measurements from individual scanlines. Moreover, to tackle the ensuing multi-view estimation problem, achieve real-time operation, and minimize latency, we develop a pair of custom solvers leveraging our geometric setup. To mitigate sensitivity to noise, we propose a geometrically consistent measurement refinement mechanism. We verify the quality of our solvers by comparing with state of the art general solvers for absolute pose estimation of generalized cameras. Finally, we demonstrate the effectiveness of our proposed approach with an FPGA-based implementation which achieves a localization throughput of 129.6 KHz with a 1.5 μs latency.

Effect of dynamic stiffness of fasteners on vibration and acoustic radiation of a ballastless track

A new model for a single wheel rolling over a metro ballastless track is developed. It is used to carry out the analysis on the effect of dynamic characteristics of fastener on the vibration and noise radiation of the wheel and the track in the vertical direction, under the excitation of the wheel/rail uneven surfaces in detail. In this analysis, a rail is modeled as a Timoshenko beam resting on discrete rubber booted short sleepers, and the sleepers are connected with the slab through linear springs and damping units, the slab is modeled by using the FE method, the fastener is characterized by using the Poynting-Thomson model which takes into account that the stiffness and dumping of the fasteners vary with vibration frequency in their service. The dynamic characteristics of the fastener include the variation of its stiffness and damping with frequency. The analysis considers that the fastener dynamic stiffness increases with the excitation frequency while its damping decreases. The vibration and acoustic radiation of the wheel/track is, to varying degree, affected by the dynamic property of the fastener. The vibration and acoustic radiation of the sleeper and the slab is greatly affected by the dynamic property of the fastener. But the effect of the total noise level of the wheel and the track by the dynamic property of the fastener is not so large because the wheel and rail noise is dominant in the whole analyzed system. These conclusions have certain reference values for the study of the vibration and noise reduction measures of the wheel and track coupled system using the fastening characteristic.

Analysis of thread rolling process using an analytical single tooth rolling model based on the slip line field theory and slab method

A thread rolling process is one of manufacturing techniques for producing high performance thread parts. Despite the importance of the process, its design has been dependent on mostly experience of experts, and the parameters of the thread rolling process may not have been systematically optimized. In this study, a new analytical model is proposed for the thread rolling process simplified as a single tooth rolling. The modeling with the slip line field (SLF) theory is used to calculate the protrusion height of workpiece, and the force and torque of the thread rolling are analytically calculated from the classical slab method. Then, the proposed model is used to analyze the effects of lubrication and plastic deformation on the performance of formed part. Moreover, experiments on the single tooth rolling process are carried out to validate the proposed modeling approach. The parametric study shows that the model can predict the force and torque of the thread rolling process with certain accuracy. The viscosity of lubricant has a significant effect on the lubrication pressure, and the friction factor determines the stress during plastic deformation. Also, it is found that the radial feed of the roller has more dominant effect on the lubrication pressure than the tangential speed by squeezing the lubrication during process.

The effects of foam rolling on ankle dorsiflexion range of motion in healthy adults: A systematic literature review

BackgroundReduced ankle dorsiflexion is associated with lower limb injury and dysfunction, with static stretching mostly used to increase ankle range of motion. Foam rolling is an alternative intervention, shown to immediately increase ankle range of motion, while the long-term application has conflicting evidence. AimsTo assess the effects of single and multiple foam rolling interventions on ankle dorsiflexion range of motion in healthy adults and appraise the methodological quality of the included studies. DesignSystematic literature review. MethodsFive electronic databases were systematically searched to identify randomised controlled trials reporting the effects of foam rolling on ankle dorsiflexion. Data was extracted from studies that met the inclusion criteria and independently appraised by each reviewer using the PEDro scale. ResultsThirty-two articles were identified; six studies included foam rolling compared to other interventions on ankle dorsiflexion range of motion. Five of the six studies reported a significant increase (p < 0.05) in ankle dorsiflexion within groups compared to baseline measurements, after a single foam rolling intervention. One study found a significant within group increase in long-term effects after foam rolling on ankle dorsiflexion over seven weeks. The mean PEDro score for all studies was 6/10 indicating a high-quality level of evidence. ConclusionThere is strong evidence suggesting that foam rolling may be effective in increasing range of motion in a healthy adult population in the short term up to 30 min; however, definitive conclusions on long-term effects cannot be drawn due to a lack of evidence, with further research recommended.

Periodic Nanoarray of Graphene pn‐Junctions on Silicon Carbide Obtained by Hydrogen Intercalation

AbstractGraphene pn‐junctions offer a rich portfolio of intriguing physical phenomena. They stand as the potential building blocks for a broad spectrum of future technologies, ranging from electronic lenses analogous to metamaterials in optics, to high‐performance photodetectors important for a variety of optoelectronic applications. The production of graphene pn‐junctions and their precise structuring at the nanoscale remains to be a challenge. In this work, a scalable method for fabricating periodic nanoarrays of graphene pn‐junctions on a technologically viable semiconducting SiC substrate is introduced. Via H‐intercalation, 1D confined armchair graphene nanoribbons are transformed into a single 2D graphene sheet rolling over 6H‐SiC mesa structures. Due to the different surface terminations of the basal and vicinal SiC planes constituting the mesa structures, different types of charge carriers are locally induced into the graphene layer. Using angle‐resolved photoelectron spectroscopy, the electronic band structure of the two graphene regions are selectively measured, finding two symmetrically doped phases with p‐type being located on the basal planes and n‐type on the facets. The results demonstrate that through a careful structuring of the substrate, combined with H‐intercalation, integrated networks of graphene pn‐junctions could be engineered at the nanoscale, paving the way for the realization of novel optoelectronic device concepts.

Effect of 'Q' Ratio on Texture Evolution of Ti-3Al-2.5V Alloy Tube during Rolling.

Ti-3Al-2.5V alloy was usually the α phase of HCP structure at room temperature which had obvious anisotropy. During tube rolling, α grain would be influenced by stress-strain state, deformation amount, ‘Q’ ratio to result the preferred orientation and formed texture. In order to obtain radial texture tube by rolling and improve the service quality of tube in the pipeline system, Φ25 mm Ti-3Al-2.5V alloy tubes was selected as billet for the experiment, and four kinds of tubes with outer diameter of Φ16mm was produced by single pass cold rolling with ‘Q’ ratios ranging from 0.65 to 2.0. The effect of ‘Q’ ratio on the texture of Ti-3Al-2.5V tube was studied. The result indicted that the initial texture of the tube is radial-circumferential equally distributed, and the radial basal texture enhances gradually with increasing ‘Q’ ratio. Since the angle between the C-axis of grain and the radial axis of RD decreases, the C-axis of grain distributes to the radial direction, and the more grain orientation from {112X} pyramidal to {0001} basal plane. The different ‘Q’ ratio would lead to different strain along the radial direction, circumferential direction, axial direction, thus affected the crystal orientation and distribution during tube rolling deformation. When ‘Q’ > 1, the tube mainly produced radial basal texture. By comparison with ‘Q’ < 1, the tube mainly produced circumferential basal texture. As a result, when the initial texture of the tube is radial-circumferential equally distributed, the ideal radial texture of the tube can be obtained by choosing rolling process with ‘Q’ > 2.0.

Effect of single roll drive cross rolling on the microstructure, crystallographic texture, and mechanical behavior of Al–Zn–Mg–Cu alloy

Effect of single roll drive cross rolling on the microstructure, crystallographic texture, and mechanical behavior of Al–Zn–Mg–Cu alloy

Multistep networks for roll force prediction in hot strip rolling mill

Hot rolling processes consist of multiple single rolling stand operating at high temperature and speed to achieve desired steel shapes and superior properties, via exerting roll forces that need to be accurately predicted by a model. The currently used model of the mill of this study shows prediction instability and is unable to accurately accommodate changes in steel grade. In this paper, we propose a machine learning based framework to establish a model that accurately predicts roll forces at each mill stands of the hot strip rolling mill. In contrast to the traditional models, the proposed expert system considers an individual model for each rolling stand and employs rolling history when predicting roll forces. The proposed model includes both steel chemistry and physical process parameters for its predictions. Our experimental results demonstrate that the proposed framework improves both prediction accuracy and stability by 40%–50% over the currently used mill model. The enhanced prediction accuracy will greatly improve dimensional and microstructural control, as well as ensuring the avoidance of mill overloads.

Effect of annealing and cold rolling on interface microstructure and properties of Ti/Al/Cu clad sheet fabricated by horizontal twin-roll casting

In this study, a Ti/Al/Cu three-layer clad sheet was fabricated using horizontal twin-roll casting (HTRC) technology. The interfacial morphology, interfacial microstructure and phases, interfacial bonding strength, micro-hardness, and tensile properties of the clad sheet under different annealing and cold rolling conditions were investigated. The surface morphology of the titanium, copper and aluminum sheets after peeling was observed. Compared with the traditional compounding process, the cast-rolling bonding process can realize the direct combination of molten metal and solid metal strip and achieve higher bonding strength. In the as-cast sheet, the thickness of the diffusion layer is 3.6 μm and the average peel strength (APS) is 20.2 N/mm at the Ti/Al interface, meanwhile the values at the Cu/Al interface are 3.2 μm and 13.8 N/mm. Before the formation of intermetallic compound (IMC) at the interface, increasing annealing temperature can improve the bonding strength by promoting atomic interdiffusion. Further cold rolling can also improve the bonding strength by forming a wavelike interface. Under the action of huge rolling force, the matrices that were not well bonded in the cast-rolling process are contacted at the atomic scale, and as a result new bonding regions are created. By improving the interfacial bonding strength, appropriate annealing and cold rolling processes make the deformation of clad sheet more cooperative. According to the results obtained in this study, the best subsequent processing technology for Ti/Al/Cu clad sheet fabricated by HTRC is annealing at 300 °C for 1.5 h followed by a single pass cold rolling with 40% reduction.

Review essay: Between the Material and the Ephemeral

Review essay: Between the Material and the Ephemeral

Multi-dimensional prediction method based on Bi-LSTMC for ship roll

When ships sail in the sea, they will move irregularly due to the influence of strong wind, waves and other complex marine environment. Among them, the ship roll is very important to the safety of ship navigation. In order to ensure navigation safety, it is necessary to predict the ship roll effectively and accurately in advance to provide a basis for ship advance control. Aiming at the problem that traditional methods and machine learning methods are not accurate for ship roll prediction, a single input single output (SISO) and multiple input single output (MISO) ship roll prediction methods based on deep learning are proposed, and the influence of input variables on the ship roll prediction model is studied. Firstly, a single input Bi-LSTMC ship roll prediction method is proposed. The network takes the advantage of LSTM time series prediction and combines convolution kernel to extract cross time features. Then the analysis and test results of six different single input prediction models are given based on real ship data. Secondly, a deep bidirectional feature network with multiple inputs of ship roll angle, roll angular velocity, relative wind speed, relative wind direction, turning angle and rudder angle is proposed for ship roll prediction. The network uses Bi-LSTM to extract forward and reverse information respectively, and introduces two Bi-LSTMC branch structures to explore the deep features between multiple input data to improve the accuracy of ship roll prediction. Finally, four error indexes were used to evaluate the proposed single input and multiple input ship roll prediction algorithms on real ship data. The applicable conditions of the single input and multiple input ship roll prediction algorithms are obtained, and the effectiveness of the proposed algorithms are also verified.

Design Improvements of Vane Bearing Compressor

A variant of vane bearing compressor with double rolling bearing had been introduced two years ago (Hu and Xu, 2019). In order to solve the problems of complex assembly process and abnormal wear in the vane bearing compressor with double rolling bearing, this paper presents a type of improved vane bearing compressor with single rolling bearing. The improved vane bearing compressor integrates the rolling bearings and the cylinder into a rolling bearing cylinder unit. The suction t and discharge ports are placed on the end face of the main bearing. With these improvements, the number of the end face friction pairs of rolling bearing inner ring is reduced by half, the number of parts is reduced accordingly, and the assembly process is thus made simpler than that with double rolling bearing. This paper introduces the operational characteristics and makes a series of structure optimization to improve the performance of the improved vane bearing compressor with single rolling bearing. The energy efficiency of the improved vane bearing compressor with single rolling bearing is found to be 5% higher than that with the double rolling bearing.

Effects of the large-scale circulation on temperature and water vapor distributions in the Π Chamber

Abstract. Microphysical processes are important for the development of clouds and thus Earth's climate. For example, turbulent fluctuations in the water vapor mixing ratio, r, and temperature, T, cause fluctuations in the saturation ratio, S. Because S is the driving factor in the condensational growth of droplets, fluctuations may broaden the cloud droplet size distribution due to individual droplets experiencing different growth rates. The small-scale turbulent fluctuations in the atmosphere that are relevant to cloud droplets are difficult to quantify through field measurements. We investigate these processes in the laboratory using Michigan Tech's Π Chamber. The Π Chamber utilizes Rayleigh–Bénard convection (RBC) to create the turbulent conditions inherent in clouds. In RBC it is common for a large-scale circulation (LSC) to form. As a consequence of the LSC, the temperature field of the chamber is not spatially uniform. In this paper, we characterize the LSC in the Π Chamber and show how it affects the shape of the distributions of r, T, and S. The LSC was found to follow a single roll with an updraft and downdraft along opposing walls of the chamber. Near the updraft (downdraft), the distributions of T and r were positively (negatively) skewed. At each measuring position, S consistently had a negatively skewed distribution, with the downdraft being the most negative.

Effect of Annealing Temperature on the Soft Magnetic Properties of Fe&lt;sub&gt;70.43&lt;/sub&gt;Nb&lt;sub&gt;10.77&lt;/sub&gt;Si&lt;sub&gt;15.77&lt;/sub&gt;Cu&lt;sub&gt;2.34&lt;/sub&gt;B&lt;sub&gt;0.69&lt;/sub&gt; Amorphous Aanostrips at 20K, 300K

Since Fe-based amorphous alloys are widely used in magnetic separators, sensors and other fields, it is of practical significance to carry out research on amorphous strips used in this field.The effects of annealing temperature on the soft magnetic properties of Fe70.43Nb10.77Si15.77Cu2.34B0.69 amorphous nanostrips with 25 μm and 28 μm thickness prepared by the single roll cold method were investigated at 20 and 300K.Five specimens were annealed at472.12K, 672.12K, 772.12K, 822.12Kand 872.12K, respectively, and their microstructure and magnetic properties were tested viametallographic microscopy, X-ray diffraction, and vibrating specimen magnetometer. At cryogenic temperatureof 20K, specimens annealed at 672,12K exhibited the best magnetic properties, including the coercive forceof8.1265A/m, saturation magnetic induction intensity of1.4351T,and its residual value of 0.2462T. The comparative analysis of experimental results obtained strongly indicates that the soft magnetic properties of the amorphous alloy are significantly improved by the particular annealing treatment.

Research on forming technology of rotary forging with double symmetry rolls of large diameter : thickness ratio discs

Abstract. Rotary forging with double symmetry rolls (DSRs) is a new metal plastic forming technology developed on the basis of conventional rotary forging with a single roll, which uses a pair of symmetrical cone rolls to realize continuous local pressure plastic deformation of the workpiece. Large-diameter, thin discs are a key component in nuclear power, aerospace, deep-sea exploration, and other fields. At present, the forming process of large-diameter discs mainly includes welding and multiple local upsetting, but these processes exhibit many defects and can not meet the requirements of industry. In this paper, a large diameter : thickness ratio disc is integrally formed by rotary forging with DSRs. Using theoretical calculation and finite element simulation methods, the stable rolling conditions and calculation formulas of force and power parameters of rotary forging with DSRs of a large diameter : thickness ratio disc are derived. Based on the reliable three-dimensional rigid-plastic finite element model, the plastic deformation characteristics of rotary forging with DSRs of discs are studied, the reliability of the stable rolling conditions and the calculation formulas of force and power parameters are verified, and the defects and causes of unstable rolling conditions are analysed. An experiment was carried out on a rotary forging press developed with double symmetry rolls, and the experimental results are in good agreement with simulation results, which demonstrated that rotary forging with DSRs is a reliable technology for forming large diameter : thickness ratio discs. The results of this research are helpful to promote the further development of rotary forging with DSRs.

MODIFIED SINGLE ROLL FLAP APPROACH FOR SIMULTANEOUS IMPLANT PLACEMENT AND RECESSION COVERAGE

PURPOSE: This presentation demonstrates the application of the recently described modified single roll flap approach in a combined approach with the coronally advanced flap for simultaneous root coverage and implant placement with augmentation of an alveolar ridge defect. MATERIAL/METHODS: A 45 years old patient presented with complaints of teeth hypersensitivity and gum recessions as a result of an extraction of a fractured tooth.The clinical examination revealed an edentulous area in the lower right mandible, position #46, presenting a III class Siebert alveolar ridge defect, with a predominant horizontal volume insufficiency.Root exposures with caries lesions were observed on the neighboring teeth - #44, #45, #47. Usually, such a combined soft tissue and bone defects require multiple surgeries to achieve complete tissue augmentation. In this case, a new combined approach was performed, using the recently described by the author modified single roll flap and the protocol of the lateral approach of the coronally advanced flap for the lower jaw. RESULT: A complete root coverage, both bucally and approximaly, was present on the 4th month after surgery. In the edentulous area, a sufficient volume augmentation was observed with a presence of an adequate height and thickness of the peri-implant mucosa to achieve a good long term success of the implant born crown. CONCLUSION: The presented case proved the benefits of the newly described modified roll flap and the possibility this approach to be implemented in different surgical techniques, thus enlarging the indications of its application.

Structure and Thermal Properties of a Ternary Al-Cr-Si Quenching Ribbon Manufactured by Single Roll Method

Al-Cr-Si ternary quench ribbons are fabricated using a single roll method and investigated for their structural and thermal properties. In particular, the sinterability is examined by pulse current sintering to obtain the following results. The Al74Cr20Si6 composition becomes a quasicrystalline single phase; by reducing the amount of Cr, it becomes a twophase mixed structure of Al phase and quasicrystalline phase. As a result of sintering of Al74Cr20Si6, Al77Cr13Si10 and Al90Cr6Si4 compositions, the sintering density is increased with the large amount of Al phase; the sintering density is the highest in Al90Cr6Si4 composition. In addition, as a result of investigating the effects of sintering temperature and pressurization on the sintered density of Al90Cr6Si4, a sintered compact of 99% or more at 513 K and 500 MPa is produced. In particular, since the Al-Cr-Si ternary crystal is more thermally stable than the Al-Cr binary quaternary crystal, it is possible to increase the sintering temperature by about 100 K. Therefore, using an alloy of Al90Cr6Si4 composition, a sintered compact having a sintered density of 99 % or more at 613 K and 250 MPa can be manufactured. It is possible to increase the sintering temperature by using the alloy system as a ternary system. As a result, it is possible to produce a sintered body with higher density than that possible using the binary system, and at half the pressure compared with the conventional Al-Cr binary system.