Circumferential Rotation Research Articles

Regulating mechanisms of external axial magnetic field on flow and heat transfer behavior for process optimization in plasma beam polishing

Plasma beam polishing has emerged as an innovative alternative to conventional metal finishing techniques. However, the precision machining ability of plasma arc encounters challenges due to the formation of surface undulations, while previous research has predominantly focused on parameter adjustments. In this paper, the feasibility of optimizing the plasma beam polishing process was validated through magnetic field regulation, as the surface topography and subsurface structure were obviously flattened. Given this, a micro plasma arc model under inhomogeneous axial magnetic field was established to explore the regulating mechanisms of the external axial magnetic field on the flow and heat transfer behavior of the plasma arc. Through this model, the plasma characteristics (magnetic induction intensity, electric potential, arc current, Lorentz force, plasma velocity and electron temperature) were comprehensively discussed. The results indicate that the external shape of the plasma arc is determined by the self-induced magnetic field, while the externally applied axial magnetic field significantly influences the internal flow of the plasma arc. The axial and radial magnetic fields generated by the excitation coil can induce circumferential rotation by dragging the plasma arc with Lorentz force, creating a more suitable energy beam for the polishing process. To verify the model, the arc temperature was measured using spectroscopic diagnostics, and the arc shape was captured using a high-speed camera, both of which were basically consistent with the simulation results.

Investigation of a 2-DOF GER fluid damper in cut mode

Dampers incorporating smart materials have attracted significant interest for their application in vibration and shock isolation. Traditionally, these dampers work through shear, flow, and squeeze modes, each unique in its strengths and limitations. However, this study introduces a working mode, termed cut mode, which integrates the strengths of these existing modes. Structurally resembling the flow mode, operationally akin to the shear mode, and behaving similarly to the squeeze mode, the cut mode promises a novel approach to damping. Consequently, extensive research has been conducted at the particle level to develop a mathematical model for the cut mode, grounded in chain formation and breaking mechanisms. Thereafter, a verification prototype damper was designed to demonstrate this concept’s practicality, with the Giant Electrorheological (GER) fluid—a rheological fluid with exceptional yield strength—being employed. This damper features a multilayer cylindrical structure tailored for the cut mode, providing 2-degree of freedom (DOF) damping capabilities. This dual-DOF design is ideal for robotic arm joint applications, as it can offer damping for both axial translation and circumferential rotation simultaneously. In addition, four orifice boards were designed, fabricated, and tested to optimize and enhance the effectiveness of the cut mode further. The results are impressive, the proposed cut mode damper exhibits superior performance characteristics, indicating its great potential for engineering applications.

A Fiber-Guided Motorized Rotation Laser Scanning Thermography Technique for Impact Damage Crack Inspection in Composites

Laser Thermography manifests superior sensitivity and compatibility to detect cracks and small subsurface defects. However, the existing related systems have limitations on either inspection efficiency or unknown directional cracks due to the utilization of stationary heat sources. This article reports a Fiber-guided Motorised Rotation Laser-line Scanning Thermography (FMRLST) system aiming to rapidly inspect cracks of impact damage with unknown direction in composite laminates. An optical head with fibre delivery integrated with a rotation motor is designed and developed to generate novel scanning heating in a circumferential rotation manner. A FEM model is first proposed to simulate the principle of FMRLST testing and produce thermograms for the development of post-processing methods. A damage enhancement method based on Curvelet Transform is developed to enhance the visualization of thermal features of cracks, and purify the resulting image by suppressing the laser-line heating pattern and cancelling noise. The validation on three composite specimens with different levels of impact damage suggests the developed FMRLST system can extract unknown impact surface cracks efficiently. The remarkable sensitivity and flexibility of FMRLST to arbitrary cracks, along with the miniaturized probe-like inspection unit, present its potential in on-site thermographic inspection, and its design is promising to push the LST towards.

Coordinated Motion of Epithelial Layers on Curved Surfaces.

Coordinated cellular movements are key processes in tissue morphogenesis. Using a cell-based modeling approach we study the dynamics of epithelial layers lining surfaces with constant and varying curvature. We demonstrate that extrinsic curvature effects can explain the alignment of cell elongation with the principal directions of curvature. Together with specific self-propulsion mechanisms and cell-cell interactions this effect gets enhanced and can explain observed large-scale, persistent, and circumferential rotation on cylindrical surfaces. On toroidal surfaces the resulting curvature coupling is an interplay of intrinsic and extrinsic curvature effects. These findings unveil the role of curvature and postulate its importance for tissue morphogenesis.

Disaster mechanism analysis for segments floating of large-diameter shield tunnel construction in the water-rich strata: A case study

During the construction of large-diameter shield tunnels crossing water-rich strata near the sea, serious disasters such as segment floating, cracking, and water leakage often occur. This study, based on field tests, identified the engineering disaster factors of segment floating and adjacent misalignment, established a numerical calculation model for shield tunnel construction considering the interaction between segments, revealed the engineering disaster derivation mechanism in the water-rich environment, proposed treatment measures for engineering disaster, and the effectiveness of the treatment measures were verified in field engineering. The research results indicate that the larger grouting pressure in the lower part of the segment will cause greater compression deformation along the radial direction, leading to greater adjacent misalignment and more obvious circumferential rotation of the segment, significantly increasing the risk of local yielding of bolts and reinforcement mesh. At the beginning of grouting, the flow velocity of pore water in the strata is the highest, and as the grout around the segment gradually solidifies, the flow velocity and accumulation range of pore water around the segment gradually decrease. The optimal grout material ratio including 200 kg of cement, 380 kg of water, 680 kg of sand, 380 kg of fly ash, and 90 kg of bentonite can effectively limit the floating displacement of the segment, and improve the assembly flatness of segment along the longitudinal direction.

Preliminary investigation on flexible cutting technology for rotating shaped cutter

The wear and impact failures of polycrystalline diamond compact cutter seriously limit its lifespan and efficiency. The flexible rotating shaped cutter is a new idea that transforms traditional rigid cutting into flexible cutting while combined with rotary cutting and plowing. The cutting test verified the feasibility of flexible cutting technology that the cutting force and its fluctuations of flexible cutting were reduced by more than 23.25% and 22.41% compared to rigid cutting. It owes to the bit-cutter elastic interaction and the cutter axial translation freedom created by the disc spring elastic element. By compressing the elastic element, buffering and vibration absorption are achieved. As the number of disc springs increases, the buffering effect improves. Driven by the shaped surface and side rake, the cutter has circumferential rotation freedom, which enables its entire circumference to participate in rock cutting, which could improve the utilization rate and reduce wear rate of the cutter. The rotation is reflected in the experimental rock scratch, the rotary speed decreases as the number of disc springs increases, increases as the side rake and depth of cut increases. The experimental results indicate that the cutting forces' magnitude and standard deviation of the flexible rotating shaped cutter increase with the increase of side rake and depth of cut. The cutting forces' coefficient of variation have a small value around 10° side rake and 1.5 mm depth of cut, which means that the fluctuation is relatively small. Therefore, the 10° side rake is the appropriate working angle and 1.5 mm is the recommended depth of cut. This investigation demonstrates that the flexible rotating shaped cutter could effectively improve the impact and wear resistance, thus preventing failures and improving the service life of drill bit cutter.

Experimental and numerical study of flame stability in a rotary flow reversal reactor with ultra-lean toluene/air mixture

A rotary flow reversal reactor with a fixed packed bed and rotary intake is established to study the combustion stability with ultra-lean toluene/air mixture. The experimental results show that the stable temperature distribution in the packed bed is vertically graded and circumferentially uniform with bottom rotary intake. The three-dimensional numerical simulation using sliding grid technology on the combustion process is presented. The effects of intake toluene concentration, axial velocity and circumferential rotation speed on the combustion stability are analyzed numerically. High intake toluene concentration or feed axial velocity will decrease the propagation velocity of the flame front and raise the peak temperature and the maximum reaction rate to achieve a quasi-steady state finally. However, the intake rotation speed has little effect on the combustion process. The work will enrich the investigation of flame stability during the filtration combustion of ultra low-calorific value gas.

Development of a Novel Ball-and-Socket Flexible Manipulator for Minimally Invasive Flexible Surgery

This work proposes a novel flexible manipulator consisting of a series of 2-DOF vertebrae based on a ball-andsocket joint that is connected by a ball-shaped surface and a cupshaped socket and constrained by pins for circumferential rotation. This manipulator can demonstrate outstanding torsional stiffness since the circumferential rotation between the vertebrae is constrained by four ball pins. The point contact between ball pins and guideways effectively reduces the friction between the vertebrae, thus allowing the designed manipulator to yield a smooth bending shape with constant curvature. This manipulator features high axial and torsional stiffness, excellent bending performance, sufficient loading capacity, and convenient integration with surgical instruments. Moreover, the excellent torsional stiffness enables this manipulator to efficiently transfer torque and be applied in in-situ torsional motion, effectively addressing the typical issue of limited dexterity for torsional motion. The kinematic modeling of the proposed manipulator under in-situ torsional motion has been derived, and its workspace has been analyzed. A robotic system has been assembled, and experiments have verified the proposed design and modeling validity. The results show that the maximum position errors in bending motion are 2.39% (horizontal direction) and 1.98% (vertical direction), and its torsional stiffness is 21.13N∙mm/deg, which is 46 times higher than that of a typical spherical flexible manipulator (SFM). Such merits support this manipulator excellently performing the in-situ torsional motion with a maximum average position error of 3.58%. Furthermore, a phantom test of the larynx has been performed to verify the potential of clinical feasibility.

Modeling of the material removal rate in internal cylindrical plunge electrochemical grinding

The material removal rate (MRR) in the internal cylindrical plunge electrochemical grinding (ICPECG) is hard to assess because it involves two feed motions: workpiece circumferential rotation and grinding wheel motion in the radial direction. This study attempts to model the MRR and electrochemical overcut in the stable grinding stage of ICPECG by using an equivalent plane electrochemical grinding model with a single feed motion. The differential equation of the interelectrode gap (IEG) in the machining area in the stable grinding stage of ICPECG is derived. Then, based on Faraday's electrolytic law, MRR models of electrochemical anode dissolution (EAD), abrasive mechanical grinding, and electrochemical overcut depth are established and numerically simulated by a variable replacement under different machining parameters. The numerical results indicate that the grinding wheel's radial feed rate most significantly influences the EAD share in the total MRR. In contrast, the power supply voltage mainly controls the electrochemical overcut depth. The proposed model's feasibility and revealed correlations are experimentally verified.

Experimental investigation on lean blowout dynamics of spray flame in a multi-swirl staged combustor

• Continuous lean blowout process of spray flames with linear reduction of fuel-to-air ratio. • Evolution of LBO performance under simulated flight-idle conditions inside a staged combustor. • LBO flame dynamics identified by proper orthogonal decomposition method. • Peak frequency transitions can be used as precursors to blowout events. Lean combustion has been widely applied in gas turbine combustors due to its superiority in reducing NOx emissions. However, it poses a significant risk of blowout for aero-engines especially when operating under low power conditions. In this paper, the LBO (lean blowout) process of spray flame was experimentally investigated and the flame was visualized by high-speed imaging of CH* chemiluminescence. A stratified partially premixed injector was applied and fueled with aviation kerosene at simulated flight-idle conditions. During the experiments, LBO was induced through linear reduction of pilot fuel flow rate. It was found that the LBO performances deteriorated as the altitude increases and the relationship between LBO FAR (fuel to air ratio) and altitude conformed to an exponential function. Evolution of flame macrostructures during LBO process showed that the flame changed from a double V-shape to a single V-shape with the decrease of FAR . FFT (fast Fourier transform) and POD (proper orthogonal decomposition) methods were introduced to post-process the high-speed imaging data in different periods before flame extinction. At the last second before LBO, POD modal distributions presented typical axial oscillation, circumferential rotation and high-order radial oscillations successively. The spectral analysis showed that the peak frequencies in the spectra of global CH* chemiluminiscence intensity and the spectra of POD modal time coefficients both changed prominently within 3∼7 seconds before flame complete extinction, which was of good repeatability during repeated tests and was considered to be a precursor for blowout event.

Analysis of flow torques during opening and closing of high-frequency rotary directional control valve

A 2D high-frequency rotary directional control valve with a spool having two degrees of freedom for axial linear motion and circumferential rotation is proposed in this paper. The axial linear motion decides the maximum orifice area, and the circumferential rotation lets the orifice area change continuously. One of the known elements impacting valve function is the flow force. This paper systematically analyzes the steady and transient flow torques subjected to the valve through theoretical analysis, AMESim-Fluent joint simulation and experimental tests. The results show that: under a single variable, the flow torques of the 2D high-frequency rotary directional control valve initially increase and then decrease like the sinusoid curve with the rotation of the spool and reach the maximum when the orifice opening is 1/2, and the flow torques are always in the direction of orifice closing and want to close the orifice. When the orifice area increases, the flow torques are the resistance, preventing the spool from opening; when the orifice area decreases, the flow torques are the power, pushing the spool to close. The steady flow torques are proportional to the pressure drop. The direction of the transient flow torque is independent of the relative position of the spool groove and sleeve window, which proportional to the square root of the pressure drop, orifice area and rotational speed. The flow torques are so important in the control of valve and can not be negligible.

The emergence of spontaneous coordinated epithelial rotation on cylindrical curved surfaces.

Three-dimensional collective epithelial rotation around a given axis represents a coordinated cellular movement driving tissue morphogenesis and transformation. Questions regarding these behaviors and their relationship with substrate curvatures are intimately linked to spontaneous active matter processes and to vital morphogenetic and embryonic processes. Here, using interdisciplinary approaches, we study the dynamics of epithelial layers lining different cylindrical surfaces. We observe large-scale, persistent, and circumferential rotation in both concavely and convexly curved cylindrical tissues. While epithelia of inverse curvature show an orthogonal switch in actomyosin network orientation and opposite apicobasal polarities, their rotational movements emerge and vary similarly within a common curvature window. We further reveal that this persisting rotation requires stable cell-cell adhesion and Rac-1–dependent cell polarity. Using an active polar gel model, we unveil the different relationships of collective cell polarity and actin alignment with curvatures, which lead to coordinated rotational behavior despite the inverted curvature and cytoskeleton order.

Circumferentially rotatable inspection robot with elastic suspensions for bridge cables

PurposePeriodic inspection of bridge cables is essential, and cable-climbing robots can replace human workers to perform risky tasks and improve inspection efficiency. However, cable inspection robots often fail to surmount large obstacles and cable clamps. The purpose of this paper is to develop a practical cable inspection robot with stronger obstacle-surmounting performance and circumferential rotation capability.Design/methodology/approa/chA cable inspection robot with novel elastic suspension mechanisms and circumferential rotation mechanisms is designed and proposed in this study. The supporting force and spring deformation of the elastic suspension are investigated and calculated. Dynamic analysis of obstacle surmounting and circumferential rotation is performed. Experiments are conducted on vertical and inclined cables to test the obstacle-surmounting performance and cable-clamp passing of the robot. The practicality of the robot is then verified in field tests.FindingsWith its elastic suspension mechanisms, the cable inspection robot can carry a 12.4 kg payload and stably climb a vertical cable. The maximum heights of obstacles surmounted by the driving wheels and the passive wheels of the robot are 15 mm and 13 mm, respectively. Equipped with circumferential rotation mechanisms, the robot can flexibly rotate and successfully pass cable clamps.Originality/valueThe novel elastic suspension mechanism and circumferential rotation mechanism improve the performance of the cable inspection robot and solve the problem of surmounting obstacles and cable clamps. Application of the robot can promote the automation of bridge cable inspection.

PARAMETER’S INVESTIGATION ON Al2O3 CERAMIC USING LASER TURNING

The investigation deals with the turning of Alumina (Al2[Formula: see text] ceramic using various parameters of the input process. The experimental design has been used based on Taguchi technology to perform the experimentation. Pulse frequency, average laser power, work piece rotational speed and feed rate are the process inputs considered during investigation. The Signal-to-Noise ratio values are used for measuring various outputs. The best amount of spot overlap has been reached with various combined parameter settings. In addition, a better width of the rotational scan has been attained by varying axial feed rate as well as the rotational speed of the work piece. Micro-turned deviation (depth) and machined surface finish at different input parametric combinations were considered as output reactions for machining. During the laser turning operation, analyses learned the effect of overlaps on the various inputs considered for output measurements such as micro-degree deviation and surface roughness. The investigation reveals that the surface finish decreases with an increase in overlap in the circumferential direction and rotation of the work sample. The maximum surface finish is 0.507[Formula: see text][Formula: see text]m achieved at a frequency of 5000[Formula: see text]Hz, 300[Formula: see text]rpm work piece cutting speed, 8.5[Formula: see text]W power and 0.4[Formula: see text]mm/s feed.

Unicoronal Craniosynostosis: Is There a Lateral Difference in Retinal Morphology?

Craniosynostosis is the premature fusion of cranial sutures in pediatric patients, which may lead to elevated intracranial pressure due to cerebro-cephalic disproportion between a growing brain and constricted skull. It is unknown whether this increased pressure is distributed equally throughout the cranial vault, or whether certain areas of the brain experience greater pressure at these regions of premature osseous fusion. Optical coherence tomography (OCT) is a noninvasive modality for detecting elevated intracranial pressure. Optical coherence tomography was utilized to measure the peripapillary retinal nerve fiber layer (RNFL) thickness in patients undergoing surgical correction of craniosynostosis. Retinal nerve fiber layer in the eye ipsilateral to the unicoronal suture fusion was compared to the RNFL in the eye contralateral to the unicoronal suture fusion. During the study interval, 21 patients met inclusion criteria. Median age at operative intervention was 8.0 months, and 28.6% patients presented with left-sided unicoronal craniosynostosis, whereas 71.4% of patients presented with right-sided unicoronal craniosynostosis. Rather than universal increase on the affected side of coronal suture fusion, retinal nerve fiber layer thickness parameters showed a rotation phenomenon, such that the patterns of elevation had a 45° circumferential rotation in the direction of intorsion. The explanation for these results remains elusive, but they likely indicate either intracranial changes transmitted differentially to the peripapillary retina, or differing retinal morphology, between the ipsilateral and contralateral eyes in unicoronal craniosynostosis.

Designing and Simulation of Electromagnetic Force Feedback Model Focusing on Virtual Interventional Surgery

<p indent=0mm>In order to generate the haptic force real-timely and accurately in virtual vascular intervention, an electromagnetic force feedback model is designed based on magnetic levitation principle to create the circumferential rotation haptic force. By analyzing the magnetic field characteristics of the electrified coil and the operation pattern of the interventional surgery, firstly the topological structure of the electromagnetic coil array and the surgical instrument model are proposed. Then the optimal current allocation strategy for the coil array is suggested and verified by simulation. Finally, the torque-current prediction model is established by utilizing the model fusion method. The experiments show that the proposed model can calculate the current with 3% error and at a frequency of about <sc>40 Hz.</sc> Combined with the optimal current allocation strategy, the crucial force feedback can be realized real-timely and accurately.

The decoupling behavior of arc coupling and rotating in seven-wire rotating arc EGW

In the present study, the decoupling behavior of the arc coupling and rotating in the seven-wire rotating arc electrogas welding (EGW) is studied. It is found that the arc motion processes is composed of the arc axial motion process, arc coupled motion process, and arc circumferential rotation process. The arc is moving up and down along the axial direction. Moreover, it is observed that as the welding current increases, the arc axial motion frequency accelerates while the corresponding motion amplitude decreases. The arc coupled motion process does not always exist, and the arc coupled motion time and arc coupled forces increase as the welding current increases. Obtained results show that the arc axial motion hinders the arc coupled motion and the arc circumferential rotation. Meanwhile, the arc coupled motion and circumferential rotation are more obvious as the welding current increases.

Studying of morphology and left ventricular function by conventional and speckle tracking echocardiography in football players

Objective: Recent studies have showed that Tissue Doppler Imaging and Speckle Tracking Echocardiography can discover these changes at functional and structural cardiac in athletes at early stage, especially at the footballers. The purpose of this research was evaluated the structural and functional adaption of left ventricular in footballer by conventional and advanced echocardiography. Materials and methods: We performed a cross-sectional study of 30 footballers who have been trained over 2 years compared to 30 healthy candidate with the same ages. We carried out TM, 2D, STE. Echo machine was Philips Affinity 50CV with QLAB version 10.04 which can analyze online or offline. Result: In comparison with control group, IVSd, LVEDd, PWTd, LVM, LVMI (p = 0.001) was different from athlete group. Left ventricular adaption trended to eccentric hypertrophy and increased left ventricular mass index. A wave was decrease velocity and increased E/A, E/El’, E/E’s ratio. Base circumferential strain, apex circumferential strain, rotation and twist (10.12 ± 1.2) (°) athletes (7.42 ± 2.6) (°) control group with (p = 0.05), were more than control group. Conclusion: Conventional and advanced echocardiography can evaluate structural and functional left ventricular adaption in athletes. Especially, STE provided more data in myocardial deformation, rotation and twist so that it can discover these changes at athlete heart in early stages Key words: Athletes heart, Speckle Tracking Echocardiography, Tissue Doppler Imaging

Strain gauges position based on machine vision positioning

In this article, in order to meet the requirement of automatic positioning before strain gauge grinding, we proposed a new machine vision algorithm based on connected region extraction and minimum circumferential rotation rectangle delineation. At first, based on the location information of the strain gauge, we used algorithms for image binaryzation, and extracted the strain gauge block by using the connected component extraction method, next roughly positioned strain gauges. And then we dispersed the part which connected to the strain gauge, moreover, found the minimum external rotating rectangle of each strain gauge in the pair of strain gauges so as to located the center of the strain gauge and realize the strain gauge positioning in the end. Then the position of other strain gauge was inferred according to the position of strain gauge in the corner. Experimental verification showed that the error of the algorithm in this article is under 0.05mm, and the algorithm met the requirements of project positioning that the error has to below 0.1mm.

Model and formulation in grinding mechanism having advanced secondary rotational axis

“Grinding Mechanism having Advanced Secondary Rotational Axis” is one of the newer plane surface grinding methods that has an uncommon abrasion mechanism. Unlike conventional methods, in Grinding Mechanism having Advanced Secondary Rotational Axis, there are two rotations of a wheel. The first rotation is the same as the conventional grinding methods, which is the circumferential rotation. The other rotation is the newly developed axial rotation, where the wheel rotates around itself perpendicular to its radial axis. In the grinding process, the grinding force, energy, power, and temperature are directly related to the material removal rate. In this article, the chip model in Grinding Mechanism having Advanced Secondary Rotational Axis was addressed and material removal rate was reformulated. The new chip ratio formula was adapted to the grinding force, energy, power, and temperature in the conventional plane surface grinding method. The chip formed in the conventional plane surface grinding method consists of two-dimensional xy plane. In Grinding Mechanism having Advanced Secondary Rotational Axis, on the other hand, the chips consist of three-dimensional xyz plane. The reason behind this is the second rotation obtained in Grinding Mechanism having Advanced Secondary Rotational Axis (axial rotational motion). The chip model was obtained from the combination of two rotations in Grinding Mechanism having Advanced Secondary Rotational Axis. As a result, the resulting chip model increased the material removal rate only slightly and this increase was negligible. Accordingly, an increase in grinding force, energy, power, and temperature was observed at negligible rates.