Radial Displacement Research Articles

Absolute calibration method of electron cyclotron emission imaging system on EAST tokamak

<sec>Electron cyclotron emission imaging (ECEI) system can provide the poloidal two-dimensional (2D) relative electron temperature perturbation profile of the core plasma with high spatial and temporal resolution. After absolute calibration of ECEI system, 2D absolute electron temperature profile and its perturbation can be provided. It can provide experimental data support for studying the local heat transport and the evolution of magnetic surface of macro magneto-hydro-dynamics instability. However, due to a large number of measurement channels and the wide measuring area of ECEI diagnostic system, the absolute calibration method in which a blackbody radiation source is used as a standard source, still has technical difficulties.</sec><sec>This paper provides an absolute calibration method of ECEI diagnostic system on EAST tokamak, which can cover all the channels of ECEI system. Firstly, the sawtooth inversion surface can be determined by measuring the relative electron temperature change before and after the collapse of the sawtooth. The magnetic surface position and the shape (<inline-formula><tex-math id="M1">\begin{document}${S_{{\text{inv}}}}$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240497_M1.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240497_M1.png"/></alternatives></inline-formula>) of the ECEI measuring area are fitted based on the position and shape of the inversion surface. Then, the one-to-one mapping relationship between laboratory coordinates of each ECEI channel and magnetic surface is obtained. Secondly, according to the assumption that the electron temperature is the same on each magnetic surface in equilibrium, the electron temperature of each magnetic surface is fitted by the electron cyclotron emission (ECE) system result, while the ECE system is absolutely calibrated. The calibration coefficient <i>k</i>(<i>i</i>, <i>j</i>) of each ECEI channel is obtained by comparing with the signal amplitude and the electron temperature on the magnetic surface. The relative error of absolute electron temperature between ECEI and ECE is no more than 6% at the same location.</sec><sec>Based on the absolute electron temperature profile provided by ECEI, the motion of the magnetic axis during sawtooth instability can be tracked. It is found that the radial displacement of the magnetic axis occurs followed by the poloidal displacement during sawtooth collapse. This result indicates that after absolute calibration, the ECEI system can provide more abundant information about experimental research.</sec>

Analysis of transverse constraint force mechanics of anchor rods based on higher order theory

Abstract Research on the mechanical properties of transverse constraint force of anchor support under different loads can help to improve work safety. In this paper, based on the higher-order shear deformation theory, the higher-order whole-local theory of anchor rods is established with full consideration of the transverse normal strain. The geometric and physical equations in the intrinsic relationship are given for the wet thermodynamic behavior of anchor rods’ transverse restraining force. The equilibrium equations of the whole-local are constructed by combining them with the principle of virtual displacement. The analytical solution of the anchor core material was calculated by applying Navier’s method. The boundary displacement conditions of the anchor core material were solved. The anchor core material was modeled by combining it with ABAQUS finite element software. The mechanical analysis was carried out from the two perspectives of the buckling problem under thermal load and the parameter change of the transverse restraining force, respectively. It was found that when the thickness of the anchor bar increased from 20 mm to 50 mm, the radial displacement of the upper layer decreased by 52.95%, and there was no significant change in the positive stress at the upper and lower interfaces. The peak value of the upper interface shear stress decreases significantly from 0.55MPa to −1.41MPa when the anchor laying method is changed from a single layer to four layers. The combination of higher-order theory with ABAQUS software can effectively analyze the change of transverse constraint force of the anchor support, which can help improve its safety.

RESEARCH ON FRACTAL HEAT FLOW CHARACTERIZATION OF FINGER SEAL CONSIDERING THE HEAT TRANSFER EFFECT OF CONTACT GAPS ON ROUGH SURFACES

Finger seal is a new flexible dynamic sealing technology, and its heat transfer characteristics and seepage characteristics are one of the main research hotspots. In this paper, based on the fractal theory, a fractal model of the total thermal conductance of the finger seal considering the heat transfer effect of the contact gap of the rough surface is established, a fractal model of the effective gas permeability of the adjacent finger seals annulus considering the gas slip effect and the temperature change is established, and a finite element calculation method of the two-way thermo-mechanical coupling for the finger seal is proposed. The results show that the solid-phase thermal conductance decreases with the increase of the scale coefficient. When the axial pressure difference is greater than 0.4[Formula: see text]MPa, the rotor speed is greater than 11,000[Formula: see text]r/min, the radial displacement excitation is [0.03[Formula: see text]mm, 0.09[Formula: see text]mm], and the temperature is less than 600[Formula: see text]K, the gas-phase thermal conductance between the finger seal and the rotor shows an increasing trend. The gas-phase thermal conductance of the finger seal and the rotor is always the main position under different working conditions. Under different fractal dimensions, the solid-phase thermal conductance gradually occupies the dominant position. Temperature has a certain effect on the effective gas permeability, and fractal dimension, scale coefficient, and axial pressure difference have less effect on the effective gas permeability. At an axial pressure difference of 0.08[Formula: see text]MPa, the numerical calculation results of the two-way thermo-mechanical coupling calculation method for finger seal are closer to the experimental results, with a maximum error rate of 1.96%. The above results further improve the theoretical research system of the heat transfer characteristics of the finger seal.

HaptiYarn: Development of an Actuator Yarn That Can Transform Everyday Textiles Into Haptic Devices.

A method of providing localised haptic feedback at precise locations on the body, utilising a lightweight textile garment is presented in this short paper. The textile comprises of subtly integrated actuator yarns (HaptiYarns) which are controlled by electropneumatic circuitry. Each yarn has two functional layers, an inner porous textile layer with limited extensibility and a second, durable outer layer made from an extensible elastomer. The HaptiYarns can provide radial forces and a maximum radial displacement of 28.09 ± 0.14 mm. It was found that the intrinsic addition of graphite powder (5% by weight), during elastomer preparation, offered better resistance to layer delamination and increased the ability of the yarn to withstand higher internal air pressures by 48%. Both the graphite-filled composite and the graphite free yarns demonstrated high durability, withstanding cyclic testing of >7500 cycles while having no significant impact on the force feedback. Finally, a wearable prototype knitted textile garment is presented with eight HaptiYarns subtly integrated within it and connected to a virtual reality (VR) program providing an immersive haptic experience. These yarns offer the potential to transform everyday clothing into wearable haptic devices with potential to revolutionise healthcare, VR-based training, gaming, and entertainment sectors.

Radial Displacement Sensorless Control at Low Speed Based on High-Frequency Voltage Injection for Bearingless Permanent Magnet Vernier Motor with Special Winding

Radial Displacement Sensorless Control at Low Speed Based on High-Frequency Voltage Injection for Bearingless Permanent Magnet Vernier Motor with Special Winding

Radial Displacement Sensorless Control of PMa-BSynRM Based on Square Wave Injection With Neural Network

Radial Displacement Sensorless Control of PMa-BSynRM Based on Square Wave Injection With Neural Network

Optimization of geometrical factors for enhanced performance of carbon fiber reinforced polymer cores under transverse loading

The high strength-to-weight ratio and ease of manufacturing of composite materials make them widely used across a variety of industries. A commonly used method of improving composite structure load-bearing capacity is to employ carbon fiber-reinforced polymer (CFRP) cores. The mechanical properties of CFRP, however, vary in different directions due to its anisotropic behavior. Due to higher tensile strength along the fibers, anisotropy can lead to failure based on directions other than the fiber orientation. A thorough analysis of CFRP core failure modes has been conducted. Experimental analysis, finite element analysis, and micromechanical modeling techniques have been used in these studies. In this research, specific emphasis has been placed on understanding failure behavior under transverse loading conditions. Failure modes have been thoroughly examined in relation to geometric parameters such as interference, wedge angle, and friction coefficient. Modeling CFRP core failure and displacement behavior was carried out using FEA simulations to validate the research findings. A comparison of the obtained results with existing literature ensured that they were accurate and reliable. Additionally, response surface methodology was employed for optimization, aiming to minimize two critical factors: radial compressive stress and core displacement. By minimizing these factors, the performance and reliability of CFRP cores in applications related to grid capacity can be enhanced. The analysis of the research data revealed that the friction coefficient and interference play significant roles as interacting factors, albeit with opposite impacts on the stresses within the CFRP cores. The optimal values for interference and friction coefficient were found to be 0.0224 mm and 0.4, respectively, to minimize radial stress. Furthermore, the wedge angle exhibited a substantial influence on core displacement, with an optimal value of 3.5°.

Quantifying muscle contraction with a conductive electroactive polymer sensor: introduction to a novel surface mechanomyography device

ABSTRACT Clinicians seek an accurate method to assess muscle contractility during activities to better guide treatment. We investigated application of a conductive electroactive polymer sensor as a novel wearable surface mechanomyography (sMMG) sensor for quantifying muscle contractility. The radial displacement of a muscle during a contraction is detected by the physically stretched dielectric elastomer component of the sMMG sensor which quantifies the changes in capacitance. The duration of muscle activation times for quadriceps, hamstrings, and gastrocnemius muscles demonstrated strong correlation between sMMG and EMG during a parallel squat activity and isometric contractions. A moderate to strong correlation was demonstrated between the sMMG isometric muscle activation times and force output times from a dynamometer. The potential wearable application of an electroactive polymer sensor to measure muscle contraction time is supported.

Volar radial Carpometacarpal dislocation of the fourth and fifth fingers

Carpometacarpal ligaments converge at the base of the metacarpal. Only very violent trauma can cause carpometacarpal dislocation. We report the case of a 23-year-old patient admitted for volar dislocation of the 4th and 5th finger with radial displacement. We did proceed to a closed reduction maintained by a splint the evolution was satisfactory with the recuperation of grip force. The mechanism of the injury can be direct or indirect. The displacement can suggest is there or not a complete rupture of the carpometacarpal ligaments. After closed reduction, the treatment can be surgical (which is preferred) with k-wire fixation or nonsurgical with splint immobilization with a close follow-up to avoid the loss of the reduction.

Investigation of different influence functions in peridynamics

Peridynamics is a non–local numerical method for solving fracture problems based on integral equations. It is assumed that particles in a continuum are endowed with volume and interact with each other at a finite distance, as in molecular dynamics. The influence function in peridynamic models is used to limit the force acting on a particle and to adjust the bond strength depending on the distance between the particles. It satisfies certain continuity conditions and describes the behavior of non-local interaction. The article investigates various types of influence function in peridynamic models on the example of three-dimensional problems of elasticity and fracture. In the course of the work done, the bond-based and state-based fracture models used in the Sandia Laboratory are described, 6 types of influence functions for the bond-based model and 2 types of functions for the state-based model are presented, and the corresponding formulas for calculating the stiffness of the bond are obtained. For testing, we used the problem of propagation of a spherically symmetric elastic wave, which has an analytical solution, and a qualitative problem of destruction of a brittle disk under the action of a spherical impactor. Graphs of radial displacement are given, raster images of simulation results are shown.

Failure mode and damage assessment of underground reinforced concrete arched structure under side top explosion

Reinforced concrete arch constructions offer practical building methods and favourable mechanical properties. The utilization of this technology is prevalent in the field of underground engineering. The present study investigates the failure mode and damage assessment of an underground, reinforced concrete-arched structure subjected to a lateral-top explosion. A series of four tests were formulated and executed to examine the dynamic response characteristics of the construction. These tests involved manipulating both the explosion distance and charge mass variables. The LS/DYNA software created an extensive three-dimensional model, including the rock, concrete, and steel bars. A numerical simulation was conducted to analyze the dynamic response process of a reinforced concrete arched structure. The simulated failure characteristics of the arched structure exhibit a high level of concordance with the experimental findings. In light of this, simulations were conducted to analyze the failure mechanisms of the arched structure when subjected to varying blasting distances and charges. The study's findings indicate that the primary mechanisms of failure observed in underground arching structures subjected to side-top blasting include spalling, shear, bending, and mixed bending-shear failure of concrete. A comparative analysis examined the impact of charge mass and blasting distance on the arch waist's radial displacement and the side wall's rotation angle. The level of damage was partitioned, and a criterion for assessing the damage to the structure was put out. The establishment of the ω-R (TNT equivalent blasting distance) curve for measuring the damage levels of an arch under a side-top blast was based on the damage grades and damage criteria.

Exploring the solvent effect on crystal morphology of naphazoline hydrochloride: Molecular dynamic simulations and experiments

The crystal morphologies of naphazoline hydrochloride (NPZ) in vacuum and binary solvent conditions (methanol + ethyl acetate, methanol + ethanol, methanol + isopropanol and 2-moxyethanol + isopropanol) were investigated by the molecular dynamic (MD) simulation and experiments. The Hirshfeld surface (HS) analysis was employed to explore the interactions in the crystal structure of NPZ, and results revealed that H···H and H···Cl/Cl···H contacts were primary contributing interactions. The attachment energy (AE) model was utilized to simulate the crystal habit of NPZ in vacuum based on the single crystal data, resulting in the identification of six morphological crystal facets. Also, the structural characteristics of dominant crystal faces were analyzed. The crystal morphologies of NPZ in different binary solvents were predicted using the modified attachment energy (MAE) model. The simulation results indicated that the solvent adsorption processes on the crystal surfaces were exothermic, and {002} face had largest morphological importance in all solvent systems. Furthermore, the experimental morphology of NPZ obtained from the methanol + ethyl acetate system was consistent with the crystal habit predicted by MAE model, which was plate-shape. On this basis, the intermolecular interactions between solvent molecules and {002} as well as {1 1––1} facets were analyzed detailly by radial distribution function (RDF) and mean square displacement (MSD), respectively. The RDF analysis indicated that N atoms of {002} face formed hydrogen bonds with O atoms of solvent molecules, resulting in an evident change in the total facet area of this face. Moreover, MSD analysis demonstrated that the absorptions of solvent molecules on the {1 1––1} face were the main factor affecting the growth rate of this crystal surface.

Biomechanical comparison of different internal fixation devices for transversely unstable Mason type II radial head fractures.

Background: The integrity of the radial head is critical to maintaining elbow joint stability. For radial head fractures requiring surgical treatment, headless compression cannulated screw fixation is a less invasive scheme that has fewer complications. The aim of this study was to compare the mechanical stability of different fixation devices, including headless compression cannulated screws and mini-T-plates, for the fixation of transversely unstable radial head fractures. Methods: Forty identical synthetic radius bones were used to construct transverse unstable radial head fracture models. Parallel, cross, and tripod headless compression cannulated screw fixation and mini-T plate fixation were applied. The structural stiffness of each group was compared by static shear loading. Afterward, cyclic loading was performed in each of the three directions of the radial head, and the shear stability of each group was compared by calculating the maximum radial head displacement at the end of the cycle. Findings: The mini-T plate group had the lowest structural stiffness (51.8 ± 7.7N/mm) and the highest relative displacement of the radial head after cyclic loading (p < 0.05). The tripod headless compression cannulated screw group had the highest structural stiffness among all screw groups (p < 0.05). However, there was no significant difference in the relative displacement of the radial head between the screw groups after cyclic loading in different directions (p > 0.05). Interpretation: In conclusion, the biomechanical stability of the mini-T plate for fixation of transverse unstable radial head fractures is lower than that of headless compression cannulated screws. Tripod fixation provides more stable fixation than parallel and cross fixation with headless compression cannulated screws for the treatment of transversely unstable radial head fractures.

NUMERICAL INVESTIGATION OF THE INFLUENCE OF THE LINK POSITIONING IN THE CORONARY STENT INSIDE THE NORMAL ARTERY: A COMPARATIVE STUDY OF TWO COMMERCIAL STENT DESIGNS

This paper investigates the performance of two commercial stent designs inside the normal artery for induced Von Mises Stress and radial displacement pattern. Investigation focuses on identifying the key design feature of the stent structure responsible for varied stress and displacement pattern. Two commercial stent designs, Supraflex (Stent S) and Yukon Choice (Stent T),are modeled using micro CT images and MIMICS® while idealized models are used for investigation. ANSYS Workbench is used to numerically expand the stent inside an idealized normal artery with inflation pressure. The stent and the artery are modeled using elastic-plastic and hyperelastic material models, respectively. The results suggest crucial influence of the link positioning in inducing an area of higher Von Mises Stress and stress gradient. The locations of a higher stress gradient are those in line with unbound stent crowns. Also, higher and uniform arterial displacement can be observed in the locations in line with the bound crown. Results also suggested a considerable difference in arterial distortion induced by two designs, causes for which can also be attributed to the differences in the link placement. The study suggests that the link connections play a crucial role in setting up stress field/radial displacement. Suitable modification of the link positioning can reduce the higher stress gradient and arterial distortion, which probably can reduce arterial injury.

Molecular dynamics simulation and properties of thermoplastic starch -- effect of water content on starch plasticization

To investigate the impact of water content on starch plasticization, the molecular dynamics (MD) simulation method was employed to investigate the hydrogen bonding energy, radial distribution function (RDF) and mean square displacement (MSD) of the starch/glycerol/water system at various water contents (ranging from 8% to 14%, based on the dry starch weight). Additionally, Glycerol-plasticized thermoplastic starches (GTPSs) were prepared using a twin-screw extruder with precise material proportions according to the simulation ratio. Subsequently, DSC, XRD, FT-IR, SEM and mechanical properties of GTPSs were evaluated. By conducting an analysis on the correlation between simulation results and TPS performance, it has been demonstrated that water molecules play a pivotal role in the plasticization process of starch. GTPS exhibits challenges in processing due to its inadequate melt fluidity at lower water content (≤11%). Conversely, excessive water content (≥13%) leads to a decline in the mechanical properties of GTPS. Considering both processing stability and material’s mechanical properties, a starch water content of 12% is deemed suitable for TPS preparation.

Methodological errors due to a non-cylindrical surface in a Jones-type cell with a removable center extension tube

The article shows an idealized model of a Jones-type cell with a removable central extension tube. Two main factors leading to the cylindricity distortion of the inner surface of the cell are considered. These are radial displacement and tube diameter inequality. Based on the finite element method (FEM), errors in measuring the resistance of a liquid column caused by the non-uniformity of the current density distribution inside the cell were determined. The methodological error with respect to the idealized model was estimated for each factor separately and in combination. The Authors show that at a radial displacement of 0.6 mm, the error can reach 0.1 %. The same error value occurs when the inequality of the diameters is only 20 μm.

Experimental Study of Piezoelectric Control for Changing Tilting Pad Journal Bearing Circumferential Angle and Radial Displacement

In order to improve the vibration performance of the oil-lubricated tilting pad bearing system, an experimental approach using a piezoelectric actuator to control two new flexible tilting pads is proposed. The performance test bench of the bearing–rotor system based on a tilting pad bearing with a flexible support is established. The different circumferential angles of the angle bearing tilting pad and the radial displacement of the displacement bearing are tested by a piezoelectric actuator. At the same time, the trajectory of the rotor center under actual operating conditions is analyzed. The experimental results show that the amplitude of the rotor journal can be significantly reduced by controlling the control variables related to the circumferential angle and radial displacement of the bearing bush. Therefore, this control improvement can improve the vibration performance of two new flexible tilting pad bearing–rotor systems. The technical means are provided for the active control of an oil-lubricated tilting pad bearing.

Discovery of Ultrasmall Polar Merons and Rich Topological Phase Transitions: Defects Make 2D Lead Chalcogenides Flexible Topological Materials

AbstractAtomic‐scale polar topological configurations, such as skyrmions and merons, have garnered enormous interest due to their rich emergent physical phenomena and promising applications in next‐generation electronics. Despite recent progress in the exploration of 2D ferroelectrics, isolated polar topological structures in 2D lattices have not yet been explored. Here, an original design principle is proposed to remove the point group limit for polar structures while achieving atomic‐scale polar topological structures in non‐ferroelectric monolayers caused by defects in 2D materials. The first‐principles calculations show that an isolated polar meron with a diameter &lt; 3.0 nm is generated in the deficient lead chalcogenide monolayer, and its formation is attributed to the synergic effects of vacancy‐induced radial atomic displacements and symmetry reduction in 2D materials. The emergent polar meron can transform to rich topological configurations under external stimuli or by manipulation of the defect concentrations. Furthermore, this strategy of atomic‐scale symmetry breaking via point defect engineering can be applied to a wide variety of 2D materials to induce polar topological structures. This work generalizes the polar topology from perovskite oxides to 2D materials, facilitating exciting opportunities to create high‐density topological configurations that enable the exploration of meron/skyrmion‐based functional nanodevices.

Shoulder Tensiomyography and Isometric Strength in Swimmers Before and After a Fatiguing Protocol.

Shoulder muscles are active during front-crawl swimming to provide propulsion and stabilize the glenohumeral and scapulothoracic joints. Researchers have proposed that fatigue might contribute to altered activation of these muscles and represent a risk factor for injuries. Tensiomyography (TMG) might function as a noninvasive tool to detect changes in contractile measures of the skeletal muscles due to exercise-induced neuromuscular fatigue, though it has not yet been used in the shoulder muscles of swimmers. To assess the effects of a fatiguing swimming protocol on shoulder muscle TMG measures and isometric strength in competitive swimmers. Cross-sectional study. Swimming pool facility. A total of 14 young front-crawl competitive swimmers (11 males and 3 females; age = 21 ± 3 years [range, 17-26 years], height = 1.78 ± 0.06 m, mass = 73.1 ± 9.2 kg). Participants completed TMG and isometric strength assessments before and after 30-minute, high-intensity swim training. The TMG assessment was performed on 7 muscles of the shoulder according to front-crawl biomechanics and the applicability of the technique to obtain data, such as time to contraction and muscle-belly radial displacement. Isometric strength was assessed using a digital handheld dynamometer during shoulder flexion, extension, external rotation, and internal rotation. Fatigue induced a smaller radial displacement, mostly observable in latissimus dorsi (-1.0 mm; 95% CI = -1.7, -0.3 mm; P = .007) and pectoralis major muscles (-1.4 mm; 95% CI = -2.4, -0.4 mm; P = .007). Only shoulder extension showed an isometric strength reduction after the fatiguing protocol (-0.03 N/kg; 95% CI = -0.05, -0.01 N/kg; F1,13 = 4.936; P = .045; ηp2 = 0.275). This study provides preliminary evidence for the usefulness of TMG to detect fatigue-induced changes in contractile properties of the shoulder muscles in swimmers, in particular the latissimus dorsi and pectoralis major.

Failure Analysis of a Needle Roller Bearing in a Megawatt Reciprocating Pump

In this paper, bearing failure was reported for a needle roller bearing used as intermediate support in a pinion shaft system. Severe deformation and wear were noticed on the working surface of the failed needle roller and around the window lintel of the bearing cage. The geometry, materials and hardness of the failed needle roller bearing were analyzed. Appearance detection, SEM and EDS analyses were carried out for clarifying the potential reasons of the needle roller bearing failure. The effect of radial displacement, Hertz contact stress and misalignment on the service life of the needle roller bearing were discussed. The excessive deformation and misalignment, resulting from the unbalanced loading and improper assembly, are the likely cause of the needle roller bearing failure.