Position Of Axis Research Articles

Performance of the Aptis Distal Radioulnar Joint Implant: A Clinical Case Series Including Four-Dimensional Computed Tomography Kinematic Analysis.

High complication rates and surgical revision rates following Aptis implant placement have been reported in the literature. This study evaluates the performance of the Aptis implant of twelve patients using four-dimensional kinematic analysis. The (mean) follow-up was 58 months. Wrist motion, grip strength, and kinematic analysis of both arms were used to investigate possible causes of the reported complications. In nine cases (75%), the proximal to distal translation of the distal radius along the ulnar axis in the affected forearm was too little or absent. Significant correlations were found between postoperative extension and translation of the distal radius along the ulnar axis and between the radial deviation and combined error. The four-dimensional kinematic analysis suggests that the current design of the implant could lead to limited restoration of the position of the forearm rotation axis and the translation of the radius along the ulnar axis.

Formalization of calculations of the basing error when installing a shaft-type workpiece in a prism

The error of the position of the axis of the cylindrical workpiece in height is considered, depending on the tolerance for the angular size of the prism. The relationship between the manufacturing error of the angle of the prismatic support for basing cylindrical workpieces for technological impact and the position of the workpiece axis in the direction of the prism axis is revealed. Nomograms are constructed to determine the position of the workpiece in a standard prism depending on the diameter of the workpiece and the error of its diametrical size. Practical recommendations for working with the nomogram are given and the scope of application of the results of the work is determined.

The move-C cervical artificial disc can restore intact range of motion and 3-D kinematics

BACKGROUND CONTEXTIn contrast to cervical discectomy and fusion, total disc replacement (TDR) aims at preserving the motion at the treated vertebral level. Spinal motion is commonly evaluated with the range of motion (ROM). However, more qualitative information about cervical kinematics before and after TDR is still lacking. PURPOSEThe aim of this in vitro study was to investigate the influence of cervical TDR on ROM, instantaneous centers of rotation (ICR) and three-dimensional helical axes. STUDY DESIGNAn in vitro study with human spine specimens under pure moment loading was conducted to evaluate the kinematics of the intact cervical spine and compare it to cervical TDR. METHODSSix fresh frozen human cervical specimens (C4–5, median age 28 years, range 19–47 years, two female and four male) were biomechanically characterized in the intact state and after implantation of a cervical disc prosthesis (MOVE-C, NGMedical, Germany). To mimic in vivo conditions regarding temperature and humidity, water steam was used to create a warm and humid test environment with 37°C. Each specimen was quasistatically loaded with pure moments up to ±2.5 Nm in flexion/extension (FE), lateral bending (LB) and axial rotation (AR) in a universal spine tester for 3.5 cycles at 1 °/s. For each third cycle of motion the ROM was evaluated and an established method was used to determine the helical axis and COR and to project them into three planar X-rays. Statistical analysis was conducted using a Friedman-test and post hoc correction with Dunn-Bonferroni-tests (p<.05). RESULTSAfter TDR, total ROM was increased in FE from 19.1° to 20.1°, decreased in LB from 14.6° to 12.6° and decreased in AR from 17.7° to 15.5°. No statistical differences between the primary ROM in the intact condition and ROM after TDR were detected. Coupled rotation between LB and AR were also maintained. The position and orientation of the helical axes after cervical TDR was in good agreement with the results of the intact specimens in all three motion directions. The ICR in FE and AR before and after TDR closely matched, while in LB the ICR after TDR were more caudal. The intact in vitro kinematics we found also resembled in vivo results of healthy individuals. CONCLUSIONThe results of this in vitro study highlight the potential of artificial cervical disc implants to replicate the quantity as well as the quality of motion of the intact cervical spine. CLINICAL SIGNIFICANCEPhysiological motion preservation was a driving factor in the development of cervical TDR. Our results demonstrate the potential of cervical TDR to replicate in vivo kinematics in all three motion directions.

Performance of Joint Structure of Bent L‐Shaped Steel Members for GFRP Wall Railings

AbstractGlass fibre reinforced polymer (GFRP) has excellent material properties such as light weight and corrosion resistance, and has been applied to bridge appendages such as wall railings. In this case, bent L‐shaped steel members (bent members) are used at the joints with the floor slab. The GFRP wall railings were designed to consider the wind loads acting on them, and the bolt holes for the anchor bolts were slotted hole for ease of installation. In this study, the effects of loading conditions and bolt arrangement of anchor bolts slotted holes in the performance of the joint structure were analytically investigated for the base joints of GFRP wall railings.The results presented that, in the initial stiffness of the base, the loading condition was smaller for the negative loading than for the positive loading, and the bolt arrangement was smaller on the outside than on the inside. It is shown that the incremental bolt axial force of the anchor bolts is borne by four bolts in the positive loading, however, is biased to only two bolts in the negative loading, focusing on the neutral axis position.

Разработка контроллера электромеханического датчика положения

Electromechanical position sensors, including sine-cosine rotary transformers, compared to sensors based on other physical principles, have greater reliability, a simple design and resistance to difficult operating conditions. This makes them attractive for use in various motion control systems that require measurement of the position of the actuator axis. However, the use of such sensors requires special hardware and software devices – controllers that ensure their operation. This article is devoted to the development of such a controller, which generates, captures, and processes signals of the sine-cosine rotary transformer. When developing the controller of the sine-cosine rotary transformer, methods of system analysis of electrical, electromagnetic and information processes and means of their implementation, methods of software development, as well as methods of experimental research were applied. A description of the controller of a sine-cosine rotary transformer in phase mode is given, taking into account the hardware and computing resources of the microcontroller which implements it. At the same time, physical processes are correlated with information processes associated with the generation, capture and procession of signals. The reasons for the decrease in the position measurement accuracy are revealed. Various technical solutions have been applied to take into account and eliminate them. Among them are the coordination of physical and information processes, taking into account the execution time of calculations by the microcontroller, analysis of the correctness of the position measurement results and their smoothing according to moving average method. The controller software has been developed, which can serve as a typical element for microprocessor-based control systems. Experimental results are obtained, illustrating the achievement of the development result. Application of various technical solutions has made it possible to ensure the accuracy of position measurement up to a tenth of a degree with a high intensity of information updating. As a result of the study, a detailed and comprehensive solution of the developing a controller for a sine-cosine rotating transformer problem is given, which is the scientific and practical value of the materials presented in the article. The results obtained can be applied in various motion control systems and serve as the basis for the development of controllers for various electromechanical position sensors.

Splicing Measurement and Compensation of Straightness Errors for Ultra-Precision Guideways.

The straightness error of guideways is one of the key indicators of an ultra-precision machine, which plays an important role in the machining accuracy of a workpiece. In order to measure the straightness error of a long-distance ultra-precision guideway accurately, a splicing measurement for the straightness error of a guideway using a high-precision flat mirror and displacement sensor was proposed in this paper, and the data splicing processing algorithm based on coordinate transformation was studied. Then, comparative experiments on a splicing measurement and direct measurement of the straightness error were carried out on a hydrostatic guideway grinder. The maximum difference between the two measurements was 0.3 μm, which was far less than the straightness error of 5.8 μm. The experiment demonstrated the correctness of the proposed splicing measurement method and data processing algorithm. To suppress the influence of the straightness error on machining accuracy, a straightness error compensation algorithm based on error rotation transformation and vertical axis position correction was proposed, and the grinding experiment of a plane optics with a size of 1400 mm × 500 mm was carried out. Without error compensation grinding, the flatness error of the element was 7.54 μm. After error compensation grinding, the flatness error was significantly reduced to 2.98 μm, which was less than the straightness errors of the guideways. These results demonstrated that the straightness error of the grinding machine had been well suppressed.

Target-less approach of wire rope rotation measurement

In the hoisting system of mine and elevator, the wire rope will generate rotational motion with unfixed axis, the rotation angle of which is a vital parameter for the system. Therefore, it is necessary to measure the rotation angle to evaluate the torsional state of the rope. This paper proposes an unfixed-axis wire rope rotation angle measurement method, which mainly includes two parts, the axis positioning of the rope and the rotation tracking process. Firstly, the axis positioning method of the rope is introduced. Then, the geometrical principle of rope rotation measurement and the framework of Lucas–Kanade tracking algorithm are explained. Finally, a simulation test and a rotation experiment verify the performance of the proposed algorithm, and the influence of axis positioning error and radius recognition error on the measurement are discussed. The proposed method provides an effective way for the measurement of wire rope.

Rotational Stability of Toric Capsular Bag–Fixated Intraocular Lenses in Duet Procedure for Reversible Trifocality

To evaluate the long-term rotational stability of capsular bag-fixated toric intraocular lenses (IOLs) in polypseudophakic eyes of patients who underwent duet procedure for reversible trifocality. Retrospective interventional case series. We included 34 eyes of 20 patients who underwent duet procedure with implantation of a monofocal toric IOL (RayOne toric, Hoya XY1AT, or a Tecnis ZCT800) into the capsular bag and a trifocal-diffractive Sulcoflex IOL into the ciliary sulcus. All toric IOLs were implanted with image-guided navigation. The manifest refraction and uncorrected and distance corrected visual acuity at far, intermediate, and near distance were measured. The position of the axis of the toric IOL was determined with the Pentacam device (Oculus GmbH) by evaluating retroillumination images. The results were compared with the preoperatively planned axis position. The median follow-up was 27 months. The spherical equivalent of manifest refraction was -0.04 ± 0.34 diopters (D) postoperatively, and the refractive cylinder was -0.14 ± 0.22 D on average. Binocular uncorrected and corrected distance visual acuity were 0.05 ± 0.11 logMAR and 0.02 ± 0.09 logMAR, respectively. The mean deviation from the calculated cylinder axis was 3.8° ± 3.5° with a median of 2.8° and a maximum deviation of 15.0°. Ninety-four percent of all eyes showed a deviation of less than 10°. The long-term axial alignment of capsular bag-fixated toric IOLs in polypseudophakic eyes was comparable to the results reported for single implantation of toric IOLs. The polypseudophakic approach did not affect the rotational stability of capsular bag-fixated IOLs.

Frequency splitting of hemispherical resonators trimmed with focused ion beams

This paper studies a high-precision etching process based on focused ion beam static trimming of the defective mass of fused silica hemispherical resonators to eliminate frequency splitting. This trimming method effectively overcomes the shortcomings of inefficiency and poor robustness, and the accuracy is seriously dependent on the stability of the trimming equipment in the traditional approach based on the harmonic form of trimming. The vibration model of an imperfect hemispherical resonator is firstly established by equating structural defects into point mass defective units, revealing that the frequency splitting is a function of the size of the equivalent defect mass and that the angular position of the stiffness axis is determined by the spatial distribution of the defect mass, which further elucidates that the frequency splitting of the resonator is the equivalent form of the defect mass on its low-frequency axis. To validate the accuracy of the present method, a simulation model of the imperfect resonator is established, and the results show that the theoretical model is in good agreement with the finite element method. Then, a high-precision nonlinear parameter identification model containing frequency splitting and low-frequency axis azimuth parameters is established based on the standing wave oscillation effect and spectral analysis, and the frequency splitting and low-frequency axis azimuth are identified by analyzing the vibration function of the hemispherical resonator. Finally, based on the parameter identification results and the ion beam removal function analysis, an ion beam trimming process is designed to eliminate frequency splitting by trimming the defective mass on the low-frequency axis. The results show that the frequency splitting after mass trimming is better than 0.001 Hz, significantly improving the hemispherical resonator's performance.

Effects of rolling motion on helical coil once-through steam generator thermal-hydraulic characteristics

Steam generators are essential for the safe, economical, and reliable operation of nuclear reactors. Helical Coil Once-through Steam Generators (HCOTSG) offer unique advantages over other types of steam generators for ship reactors or offshore platforms. To investigate the effect of rolling motion due to ocean conditions on the safe and economic operation of HCOTSG, a new model and a new code are developed in this paper. The program is developed and allows numerical simulation of HCOTSG under ocean conditions. The validity of the code was verified by comparing the simulation results with the design parameters of the Marine Reactor X (MRX) steam generator and the simulation results of other dedicated programs. The code was further used to perform the International Reactor Innovative and Secure (IRIS) transient operating conditions under typical rolling motions. Then, the influences of different swing directions, angles, periods, and positions of swing axes from the origin of the system operating parameters are analyzed.In the cases discussed in this paper, the following conclusions are obtained: (a) The direction of the swing significantly affects the system. The most dangerous situation is around the x-axis, and the case around the z-axis is the safest, in which the rolling situation has little effect on the system because the centripetal force is perpendicular to the tube wall, and the gravitational pressure drop is constant. (b) when the swing angle increases, except the fluctuation speed is faster, the fluctuation range of the parameters also increases. (c) when the swing period changes, the parameters’ fluctuation range also change (d) the orientation of the swing axis from the origin affects the magnitudes of the parameters’ changes (e) the distance of the swing axis from the origin affects the magnitude of the parameter variation and the farther the swing axis is from the origin, the greater the parameter fluctuation.

A comprehensive experimental study of enhanced solid particle erosive resistance on the inner/outer surface of graphene nanoplatelets modified basalt/epoxy composite pipe

AbstractBasalt fiber reinforced polymer (BFRP) composite pipe is an excellent alternative to glass and carbon fiber reinforced composite pipes in industry and promising in high recycling for polymer composite used in aerospace, marine, and automotive. To enhance the solid particle erosion (SPE) properties of filament‐wound BFRP composite pipe while preserving its mechanical properties, reinforced BFRP composite pipes were prepared to employ non‐functionalized graphene nanoplatelets (GnPs) at a reinforcement concentration of 0.25 wt.% and ultrasonication mixing technique. The SPE behavior of GnPs reinforced and non‐reinforced BFRP composite pipes were characterized by axial and radial positioning of the inner and outer surfaces of the pipes. In each case, the erosion rates of these composite pipes were evaluated at five impingement angles (30°, 45°, 60°, 75°, and 90°) and an impact velocity of 34 m/s. The erosion response of both BFRP composite pipes' outer surfaces showed a semi‐ductile in the axial positioning, with a maximum erosion rate at a 60° impingement angle. However, these composite pipes' inner surfaces in the same positioning presented a maximum erosion rate at a 45° impingement angle. Besides, it is explored that the GnPs contribute to an improvement of approximately 10%–55% in erosive wear resistance of the non‐reinforced BFRP composite pipes. The damage analysis of eroded surfaces was examined through scanning electron microscopy (SEM), and the GnPs effect upon composite pipes' erosion micromechanisms was presented and discussed in detail.Highlights GnPs increased the BFRP composite pipe's erosion resistance. Erosion rate on the inner surface increases due to particle accumulation. GnPs improved erosion behavior via solid lubrication and mechanical properties.

Fan Flutter Mechanisms Related to Blade Mode Shape and Acoustic Properties

Abstract The blade mode shape and acoustic properties are important factors that affect the aeroelasticity of fan blades. The goal of this paper is to investigate the stall flutter mechanism associated with the first mode and its components. The paper numerically studies the impact of blade modes on fan flutter under different acoustic propagation conditions. The research focus includes unsteady characteristics inside blade passages, variations in pressure waves under different acoustic modes, as well as the effects of blade modes on the least stable phase angle. The results show that the twist-induced pressure leads to destabilization. Compared with the work of other authors, this study discovered that when the twist-induced pressure on the pressure side act on the plunge rather than twist, the instability effect will be greater, while the effect of twist-induced pressure on the suction side is weak. The phase of unsteady pressure in two-dimensional flow regions is linear with frequency, while the amplitude is highly sensitive to acoustic properties. The plunge-induced pressure inside the passage undergoes significant changes when downstream from acoustic cut-off to cut-on. The twist-induced pressure is more sensitive to changes in the acoustic propagation state, with the peak of the aerodynamic damping curve near upstream acoustic resonance being solely related to the twist-induced pressure acting on the suction side. The study also finds that the position of the blade torsion axis, represented by the twist-to-plunge ratio, does not affect the most unstable nodal diameter.

Bending characteristics of stacked REBCO cable under different stacking modes

High-temperature superconducting tapes provide new materials for various high-current applications. The stacked tape cable (STC) is one of the promissing structure, which is based on the idea to stack single REBCO tapes. However, stacking the tapes increases the thickness of the cable and reduces its bending performance. In order to study the bending behavior of stacked tapes, bending tests of single tape was first made to analyze the strain of the REBCO layer at different bending radii, and the strain-current curves were obtained by empirical equations. The cables were stacked in both back-to-back and face-to-face modes. The strains of the REBCO layers in the tapes are calculated, and the critical currents of the cables are experimentally measured at various bending radii. The bending characteristics of the cable are analyzed using the fitted equation, and the experimental results demonstrate good agreement with the calculated results. The results indicate that the REBCO layer exhibits improved bending performance under compression, and thinner cables perform better. Therefore, we added copper tape to adjust the position of the neutral axis to optimize the bending performance. The results show that this method can effectively reduce the bending radius of the stacked cable.

Virtual Sensor of Gravity Centres for Real-Time Condition Monitoring of an Industrial Stamping Press in the Automotive Industry.

This article proposes the development of a novel tool that allows real-time monitoring of the balance of a press during the stamping process. This is performed by means of a virtual sensor that, by using the tonnage information in real time, allows us to calculate the gravity centre of a virtual load that moves the slide up and down. The present development follows the philosophy shown in our previous work for the development of industrialised predictive systems, that is, the use of the information available in the system to develop IIoT tools. This philosophy is defined as I3oT (industrializable industrial Internet of Things). The tonnage data are part of a set of new criteria, called Criterion-360, used to obtain this information. This criterion stores data from a sensor each time the encoder indicates that the position of the main axis has rotated by one degree. Since the main axis turns in a complete cycle of the press, this criterion allows us to obtain information on the phases of the process and easily shows where the measured data are in the cycle. The new system allows us to detect anomalies due to imbalance or discontinuity in the stamping process by using the DBSCAN algorithm, which allows us to avoid unexpected stops and serious breakdowns. Tests were conducted to verify that our system actually detects minimal imbalances in the stamping process. Subsequently, the system was connected to normal production for one year. At the end of this work, we explain the anomalies detected as well as the conclusions of the article and future works.

Online Calibration of RIMU Based on Multistage EKF

Redundant inertial measurement units (RIMUs) are more reliable than normal IMUs, but they are suffering from the calibration of non-orthogonal gyroscopes and accelerometers. In this paper, aiming at the problem of relying on the orthogonal axis IMU information and error term coupling in the online calibration of RIMUs, a method based on the multi-stage EKF algorism is proposed. In this method, the calibration model of the inertial system is established, which does not depend on the orthogonality with the inclined axis inertial system, meanwhile, the attitude, velocity, and position information is taken as the measurement, and a filtering model is established based on the EKF method. Based on this model, the observability of the calibration method is proved, and the window and threshold for secondary filtering are set to reduce the coupling effect of scale factor error and installation error. The digital simulation indicates that the proposed method can provide high-precision online calibration results for the inclined axis scale factor error and installation error of RIMUs, and the calibration error is below 10%.

Subjective Visual Vertical test with the 3D virtual reality system: effective factors and cybersickness

Background 3D Virtual Reality (VR) offers new opportunities in vestibular science. It also presents new challenges and problems. Aims/objectives The study aimed to evaluate the effective factors in the 3D VR Subjective Visual Vertical (SVV) test and the impact of cybersickness on the test results. Material and methods The effect of the foam surface, head position in the yaw axis, moving background, and arm position holding the controller was tested. Cybersickness was evaluated using the Simulator Sickness Questionnaire (SSQ). Results The head position and controller holding style significantly affected the results. The foam surface and the moving background did not have a significant effect. Although 61.4% of the patients fell into the bad category according to the symptoms of the SSQ score, cybersickness did not significantly affect the SVV results. Conclusions and significance In 3D VR SVV, additional factors should be considered: the headset’s weight, head position, and how we hold the controller. The A-effect emerged when the head was 45 degrees turned on the yaw axis. A significant shift was detected in the test, with the arm holding the controller at 90 degrees. Most subjects felt cybersickness at a considerable level. Cybersickness should always be taken into account in VR when planning new applications.

Adaptive PID sliding mode controller application to position control of hydraulic system

This study proposes a sliding mode controller combined with the direct parameter adjustment method of proportional–integral–derivative (SMCPID) to control a hydraulic cylinder system. A simulation model using a hydraulic cylinder and a damper is set up to verify the results and accuracy of the proposed controller. In the SMCPID controller, a PID controller is used to generate a control signal combined with the sliding plane to stabilize and sustain the sliding mode. Due to the hydraulic system's nonlinear nature, the PID controller's coefficients need to be calculated and adapted according to an adaptive law. The SMCPID controller has been tested and compared with other controllers such as the PID controller, fuzzy controller combined with PID, and fuzzy controller combined with adaptive PID in controlling the position of the cylinder axis for different target paths. Simulation results are performed to verify and analyze the effectiveness of the proposed controller.

Stress-strain state and load ability of compressed pipe-concrete elements

In the article are presented the results of stress-strain state and the bearing capacity of compression pipe-concrete elements studies. The studies were carried by using a fractional-rational diagram of relationship between stress and strain proposed in the Eurocode for a compressed concrete core inside a pipe and a symmetrical two-line diagram with limited area of fluidity for any values of an arbitrary flexibility of element and eccentricity of compressive force. On the carried research basis has been developed an effective numerical technique for determining the stress-strain state and the bearing capacity of compressed pipe-concrete elements. In calculation technique constructing, the task solution is reduced to system of nonlinear algebraic equations solving, relative to the deformation level in the most stressed section of the compressed concrete core section and the position of the neutral axis in this section. The efficiency of the proposed calculation method has been verified by numerous numerical experiments. It is shown that depending on the element's flexibility and the compressive force's eccentricity, at the moment of bearing capacity loss, the operation of the steel pipe can be both elastic and elasticplastic, and this is determined only by calculations using the proposed general method. Keywords: concrete; steel pipe; «load-deflection» graph; deformation; stress; deflection; stress-strain state; bearing capacity; eccentricity.

In Ukrainian

The goal of the research work was the pyrolytic synthesis of straight and spiral carbon nanotubes of approximately the same diameter, as well as their comprehensive analysis. To solve the given problem, a new installation for the pyrolytic synthesis of carbon nanostructures (CNS) with a fusion reactor, which for each fusion process can have its own angle relative to the classical horizontal position of the reactor axis. This reactor made it possible to develop a method for obtaining conglomerates of spiral-shaped multi-walled carbon nanotubes with a diameter of 15–60 nm and to synthesize straight multi-walled carbon nanotubes with a diameter of 5 to 60 nm. The research of pyrolytic synthesis of carbon nanostructures in a vertical reactor allows to work out the technology of purposeful synthesis of nanotubes that have a spiral shape with a certain diameter and pitch of the turn. As part of the work, a new mechanism for the formation of spiral multi-walled carbon nanotubes is also considered and proposed, which is important for their further industrial synthesis and their use in related composites. A scheme is proposed of conditions for the synthesis of carbon nanostructures by the pyrolytic method. Thermal analysis was carried out in the work, which recorded the presence of two different structures with low thermal stability (probably amorphous carbon and higher hydrocarbons). When using scanning and transmission electron microscopy, the formation of spiral nanofibers with a diameter of 15–60 nm in the vertical position of the reactor was recorded, and in the horizontal position of the reactor, the formation of straight and slightly curved MWCTs with a diameter of nanofibers from 5 to 60 nm was found. Raman spectroscopy confirms the presence of multi-layered carbon tubular formation, i.e. MWCT, in both synthesis products.

Andy’s ‘T-pin’Crown and root aligning auxillary

Orthodontists strive for accurate bracket positioning as it helps in achieving an ideal occlusion more easily. For accurate bracket positioning in direct bonding, various hand-held dental instruments are used. Instruments such as, the Boone and Dougherty gauges, MBT gauges, A-KAM and various other modifications, are used for accurate positioning of brackets. Sometimes the bracket can easily slip when the instrument is removed. So, position adjustments are difficult with such an instrument. Indirect bonding is an easy solution, but it is time-consuming and there is no precise repositioning of brackets that fall off and it does not provide proper root paralleling. This led us to develop an auxiliary which can be used for crown and root paralleling or aligning, horizontal, vertical and axial positioning of bracket (Pre-Treatment assessment) during direct bonding. This will avoid the step of repositioning of the bracket at mid or end of the treatment.