Kinematic Theory Research Articles

On some properties of Hassani transforms

In the present paper, based on the ideas of Algerian physicist M.E. Hassani, the generalizedHassani spatial-temporal transformations in real Hilbert space are introduced. The originaltransformations, introduced by M.E. Hassani, are the particular cases of the transformations,introduced in this paper. It is proven that the classes of generalized Hassani transforms donot form a group of operators in the general case. Further, using these generalized Hassanitransformations as well as the theory of changeable sets and universal kinematics, the mathematicallystrict models of Hassani kinematics are constructed and the performance of the relativityprinciple in these models is discussed.

A Symmetry-Based Kinematic Theory for Nanocrystal Morphology Design.

The growth of crystalline nanoparticles (NPs) generally involves three processes: nucleation, growth, and shape evolution. Among them, the shape evolution is less understood, despite the importance of morphology for NP properties. Here, we propose a symmetry‐based kinematic theory (SBKT) based on classical growth theories to illustrate the process. Based on the crystal lattice, nucleus (or seed) symmetry, and the preferential growth directions under the experimental conditions, the SBKT can illustrate the growth trajectories. The theory accommodates the conventional criteria of the major existing theories for crystal growth and provides tools to better understand the symmetry‐breaking process during the growth of anisotropic structures. Furthermore, complex dendritic growth is theoretically and experimentally demonstrated. Thus, it provides a framework to explain the shape evolution, and extends the morphogenesis prediction to cases, which cannot be treated by other theories.

Progressive debonding analysis of sandwich composite strips using a cohesive-layerwise spectral finite element model

This paper presents a novel numerical framework for the simulation of debonding growth in sandwich structures via a layerwise spectral finite element model. A variable kinematic layerwise theory is developed, which employs cubic Hermite splines for the composite facesheets and the core and linear interpolation functions for the thin resin-rich layers in connection with continuum damage mechanics for tracking of debonding propagation. The layerwise mechanics and continuum damage mechanics are integrated into a spectral finite element, termed thereafter as cohesive-layerwise spectral finite element, with integration points collocated to nodes and high-order spatial approximation in the plane of the structure. The developed computational model is applied to global mode I, mode II, and mixed-mode fracture problems and correlated with experimental results and reference high-fidelity finite element models. The evaluation cases of the present method reveal significant enhancements in computational speed and meshing process due to elimination of cohesive layer parameter calibration, alleviation of FE aspect ratio constraints and high-convergence rates.

Impact of assimilating dam outflow measurements to update distributed hydrological model states: Localization for improving ensemble Kalman filter performance

This paper presents an investigation on the effect of dam operation on the ensemble Kalman filter (EnKF) performance in a distributed hydrological model based on kinematic wave theory. For this purpose, two flood events in a mountainous catchment in Japan are selected, and the model error parameters for the EnKF implementation are first determined through a series of experiments by varying the input error magnitude, state variable perturbation, and its correlation length. Then, through the assimilation of dam outflow observations, it is shown that special treatment of such measurements is critical in ensuring the success of the filter when flood control operation significantly changes the flow hydrograph and when the covariances between distant grids are high. Localization methods based on Euclidean distance, flow accumulation values, and river distance are all able to limit the deleterious updates to model states at distant grids and improve filter efficacy. However, no single localization approach is found to be consistently optimal for varying noise configurations, number (and type) of assimilated stations, or flood events. Separate localization of dam outflows from streamflow measurements by assuming the dam grids to be only related to their downstream grids shows potential in improving prediction at locations near the dams themselves while minimizing disruptions at long distances.

3D-Printed Guides in Bone Tumor Resection: Studying Their Error and Determining a Safety Margin for Surgery.

3D-printed guides, which have recently been introduced in orthopedic oncology, improve resection accuracy compared with traditional bone resection methods, but there are inaccuracies associated with them. These inaccuracies could lead to disastrous outcomes such as positive tumor resection margins. In this Sawbone study, we sought to quantitatively investigate the margin of error for various jig types and to determine a "safety margin" that could serve as a guide for surgeons and jig engineers in creating 3D-printed jigs that would reduce the risk of potential disastrous results such as positive margins. Various 3D-printed jigs were used to simulate wide resection of a distal femoral bone sarcoma on Sawbone specimens by 10 individuals with no specific prior expertise in cutting guides. We developed a mathematical model using kinematic theory. We defined a safety margin as the amount of change in the osteotomy lines that must be incorporated into the jig design to ensure that the surgeon is at least 98% likely not to have a positive tumor margin. Experiments were conducted to determine the mean deviation experienced in placing cutting guides on the bones. The mean deviation for the four types of cutting guides ranged from 2.86 mm to 6.54 mm. We determined that a jig design should have a safety margin of 4.8 mm for standard guides and 8.65 mm for gusset guides to minimize the possibility of cutting into the tumor as a result of human error in guide placement. Further studies involving cadavers and patients are warranted. [Orthopedics. 2022;45(3):169-173.].

Nonlinear static and dynamic performance of CNT reinforced and nanoclay modified laminated nanocomposite plate

Under static and dynamic loading circumstances, the mechanically and thermo-initiated nonlinear static and dynamic assessment of the bending response of single-walled carbon nanotubes’ (CNTs’) fibers with a nanoclay particle reinforced polymer hybrid laminated composite plate is investigated. To evaluate the effective elastic characteristics of the CNTs’ fibers on the nanoclay particle modified polymer hybrid laminated plate, a modified Halpin–Tsai method is applied in an orthotropic way. The theory of higher-order shear deformation and complete kinematics (nonlinear) are used to develop the fundamental nonlinear dynamic formulation. A user-interactive finite element method-based MATLAB program solves the governing equations for nonlinear dynamic systems utilizing Newmark’s period integration and the Newton–Raphson method. The effects of variation in the quantity of CNTs’ fibers and particles of nanoclay, presence of interphases around CNTs’ fibers and nanoclay particles, variation in phases of the CNTs’ fibers on the nanoclay particle modified polymer hybrid laminated plate, and variation in plies of the laminated hybrid plate under clamped and simply supported conditions on the transverse central deflection response are explored in depth.

Определение частот свободных колебаний для подземного нефтепровода большого диаметра с учетом влияния демпфера

The article considers the problem of determination of the spectrum of frequencies and forms of natural oscillations for an underground main pipeline of large diameter (> 1000 mm), taking into account the damper. The problem solution is constructed using the theory of cylindrical shells of medium bending. The damping effect of the soil is taken into account in the radial component of the inertia forces and is based on the kinematic theory regarding the assumption of the medium resistance proportional to the speed of the median surface element moving in this medium. There have been obtained results, the analysis of which shows that the influence of the damper makes a significant correction in determining the frequencies in the direction of their decrease. The higher the dynamic viscosity of the soil, the more significant is the discrepancy of the results between ωmn и ω* mn. With an increase in the dynamic viscosity coefficient, the frequency decreases, and at certain values the damping coefficient dm = ωmn, which is the boundary of the transition from periodic to aperiodic oscillations, that is, there is no oscillatory process.

Kinematic analysis of seven-degree-of-freedom exoskeleton rehabilitation manipulator

This article analyzes the forward kinematics and inverse kinematics of the seven-degree-of-freedom exoskeleton rehabilitation manipulator. Denavit–Hartenberg coordinates are used to model the forward kinematics, and the working space of the end effector of the manipulator is analyzed according to the joint motion range of the human arm. In the inverse solution of the seven-degree-of-freedom exoskeleton rehabilitation manipulator, the self-motion angle [Formula: see text] of the elbow is used. The minimum energy standard is used to calculate the self-motion angle [Formula: see text]. The minimum energy mainly includes the gravitational potential energy of the upper limbs and the elastic potential energy stored in the muscles. Thus, the inverse solution formula of the seven-degree-of-freedom exoskeleton rehabilitation manipulator is derived. When calculating the angle [Formula: see text], an auxiliary parameter is introduced to solve the self-motion manifold of the manipulator. Finally, the theoretical derivation and verification of the forward and inverse kinematics are carried out in this article, and through analysis of the results, it is concluded that the inverse kinematics of this article has some limitations but the theory of inverse kinematics is feasible.

Beam splitting characteristics of crystal X-ray Laue diffraction

The beam splitter is an optical element that divides a beam of light into two or more subbeams. It is an essential component in many optical experiments. X-ray has the characteristics of short wavelength and strong penetration ability, making it hard to use the optical elements in the visible-light region. Therefore, it is necessary to develop optical elements suitable for X-rays. The atomic layer spacing of the perfect crystal is of the same order of magnitude as the X-ray wavelength, so the crystal diffraction effect can be used to achieve the X-ray modulation. In this paper, the beam splitting characteristics of Laue crystal are analyzed based on X-ray diffraction dynamics and the influences of crystal absorption and incident light angular divergence on the rocking curves of transmission and diffraction are simulated. The modulation of the crystal diffraction in-plane angle and crystal thickness to Laue diffraction beam-splitting ratio is presented quantitatively. The results show that the kinematical theory of X-ray diffraction is not enough to analyze the beam splitting characteristics of the crystal. It is necessary to consider the interaction between the wave fields in the crystal and use the Pendellӧsung effect in the dynamical theory of X-ray diffraction to explain the change of the crystal beam-splitting ratio quantitatively. The influence of angular divergence and crystal absorption are considered in the simulation. The angular divergence broadens the bandwidth of the diffraction, thereby reducing diffraction intensity. The crystal absorption results in asymmetry and peak shift of the transmission curve and affects the intensity of diffraction and the intensity of transmission beam. The experimental results show that the non-dispersive (+n, –n) configuration can effectively eliminate the influence of angle divergence. The beam-splitting ratio can be adjusted in a small range (±2%) by changing the in-plane angle and adjusted in a wide range (±75%) by changing the crystal thickness, thereby realizing the quantitative modulation of the intensity of transmission and diffraction beam.

Finite-difference propagation for the simulation of x-ray multilayer optics

Recent progress in nanofabrication, namely of multilayer optics, and the construction of coherent hard x-ray sources has enabled high resolution x-ray microscopy with large numerical aperture optics for small focal spot sizes. Sub-10 nm and even sub-5 nm focal spot sizes have already been achieved using multilayer optics such as multilayer Laue lenses and multilayer zone plates. However these optics can not be described by the kinematic theory given their extreme aspect-ratio between the depth (thickness) and the layer width. Moreover, the numerical simulation of these optics is challenging, and the absence of an accessible numerical framework inhibits further progress in their design and utilization. Here, we simulate the propagation of x-ray wavefields within and behind optical multilayer elements using a finite-difference propagation method. We show that the method offers high accuracy at reasonable computational cost. We investigate how small focal spot sizes and highest diffraction efficiency of multilayer optics can be achieved, considering volume diffraction effects such as waveguiding and Pendellösung. Finally, we show the simulation of a novel imaging scheme, allowing for a detailed study of image formation and the development of customized phase retrieval schemes.

Simulation, Modeling and Experimental Research on the Thermal Effect of the Motion Error of Hydrostatic Guideways.

Hydrostatic guideways are widely applied in ultra-precision machine tools, and motion errors undermine the machining accuracy. Among all the influence factors, the thermal effect distributes most to motion errors. Based on the kinematic theory and the finite element method, a 3-degrees-of-freedom quasi-static kinematics model for motion errors containing the thermal effect was established. In this model, the initial state of the closed rail as a “black box” is regarded, and a self-consistent setting method for the initial state of the guide rails is proposed. Experiments were carried out to verify the thermal motion errors simulated by the finite element method and our kinematics model. The deviation of the measured thermal vertical straightness error from the theoretical value is less than 1 μm, which ensured the effectiveness of the model we developed.

Design and motion analysis of a small motor stator multi-wire paralleled winding hybrid robot

Abstract. The working space of small motor stators is narrow, and most of them are manual winding. It is difficult to guarantee the uniform arrangement of enameled wires by multi-wire winding. To solve these problems, a three-phase parallel equivalent multi-wire winding robot is proposed to achieve large output torque of the motor. Firstly, according to the equivalent model, the structure of the large arm, small arm and manipulator is designed to determine the motion model of the winding robot. Euler's kinematics theory is used to analyze the change of the working position of the arm, and the rotation matrix of the arm and the constraint equation of the motion vector of each branch chain are established. The motion model of the arm and the manipulator are established using inverse kinematics and analytical analysis. The motion pose of each joint of the winding robot is studied to ensure that the robot realizes a three-phase parallel multi-wire winding motion. ADAMS software was used for kinematic simulation analysis of the winding robot. The displacement of the branch chain on the xyz axis was represented by the torque of the virtual motor to verify the correctness of the inverse kinematics solution and the closure condition of the manipulator block. Finally, the ROS simulation platform is built to simulate the joint motion planning of the winding robot to verify the multi-line parallel principle and the feasibility of the multi-line parallel winding hybrid robot. The research results of this paper provide a theoretical reference for multi-wire parallel winding equipment control.

A Distributed Conductance Cross-Correlation Method for Measuring Low-Velocity and High Water-Cut Oil-Water Flows

Oil-water two-phase flow widely exists in the oil production and transportation. The flow pattern presents obvious complexity due to non-uniform distribution of water and oil. When the onshore oilfields are on a middle-late stage of oil recovery, the oil production gradually decreases and the water-cut increases. Accurate measurement of oil-water two-phase flow is a significant issue to improve oil production performance and optimize oil reservoir management. Therefore, we propose a distributed four-sector conductance cross-correlation sensor to realize the flow pattern classification and the measurement of flow velocity and water holdup for low-velocity and high water-cut oil-water flows in a 20 mm inner diameter pipe. The geometry dimension is optimized according to the sensitive field distributions of the sensor. In the flow loop test of vertical upward oil-water two-phase flow, the output signals measured from upstream and downstream electrodes are used to figure out three flow patterns combining with a high-speed camera, and the cross-correlation velocity. Then we use the kinematic wave theory to connect the relationship between the cross-correlation flow velocity and the mixture flow velocity considering water- cut and flow patterns. In addition, according to Maxwell equation, we calculate the water holdup. Finally, a drift velocity model based on three flow patterns is constructed to measure the oil phase superficial velocity.

Decomposition of the Shear Capacity of Steel Fiber–Reinforced Concrete Coupling Beams

AbstractSteel fiber–reinforced concrete (SFRC) is extensively used in coupling beams due to its superior mechanical properties. In this study, the two-parameter kinematic theory is modified by intr...

Comprehensive measurement model of geometric errors for three linear axes of computer numerical control machine tools

The geometric error measurement of computer numerical control (CNC) machine tools is developing towards automation and high precision. This not only improves the measurement efficiency, but also reduces the error caused by the long measurement time. This paper proposes a high-efficiency, automatic method of measuring 21 geometric errors of the three linear axes of CNC machine tools and establishes a comprehensive measurement model. The measurement system and model are applicable to linear axis geometric error measurement for all CNC machine tools. The measurement model was developed using rigid body kinematics theory and combined with the ray-tracing method. It mainly analyses the error crosstalk, system errors caused by optical components, laser beam drift, and non-parallelism errors between the measuring beams. ZEMAX was used to verify the model accuracy. Further, repeatability and comparison experiments were conducted to confirm the reliability and accuracy of the measurement system and model.

Mixed electrolyte effect on the stability of the interface between two immiscible electrolyte solutions

Polarization and interfacial tension measurements at an electrolyte dropping electrode or a sessile electrolyte drop are used to investigate the instability of the interface between the aqueous solution of LiCl and the organic solvent containing a mixture of the electrolytes composed of the non-adsorbing ions, here tetrabutylammonium tetraphenylborate (TBATPB) and bis(triphenylphosphoranylidene) ammonium tetrakis (pentafluorophenyl)borate (BATB). The instability is manifested by a substantial current enhancement and decrease of the interfacial tension accompanied by the vigorous mechanical oscillations of the drop. In contrast, no instability is observed when the organic solvent phase contains TBATPB or BATB alone. It is proposed that the hydrodynamic instability has the origin in the small faradaic current associated with the trace ion transfer, and that the initiating impulse is generated by the perturbation of the stratified distribution of the ions with the significantly different sizes (e.g., TBA+ and BA+) on the organic side of the interface. Effects of the potential and the electrolyte concentration on the current enhancement and the interfacial tension reduction are explained by the kinematic theory that has been established by Aogaki et al. (Electrochim. Acta 23 (1978) 867).

Design and Implementation of Inverse Kinematics and Motion Monitoring System for 6DoF Platform

Six-axis motion platforms have a low contraction height and a high degree of freedom. First of all, the designed six-axis crank arm platform, including the motor, reducer, crank arm, link, platform support arm, and upper and lower platforms, can be designed for different bearing requirements. Secondly, it uses a coordinate transform and kinematics theory to derive each motor rotor angle. A set of platform data acquisition (DAQ) monitoring modules was established, and the LabVIEW programming language was used to write measurement software. The monitoring items include displacement, speed, and acceleration, which can be displayed on the screen and recorded by an industrial computer in real time and dynamically. Then, an RS-485 or RS-232 communication transmission interface was used to provide the control system with the related movement information. Finally, an industrial computer combined with a motion control card was used as a control kernel to realize the control algorithms, internet module function, I/O write and read signals, firmware integration, and human–machine interface message. The experimental results validate the appropriateness of the proposed method.

Reliability of the kinematic theory parameters during handwriting tasks on a vertical setup

BackgroundThe Kinematic Theory and its Sigma–Lognormal model have been used extensively in motor control analyses. It has recently shown promise in its ability to detect neuromuscular fatigue in the shoulder. The use of an ergonomic setup composed of a vertically oriented tablet offers a good demonstration for use in future clinical applications. However, parameters’ reliability of this theory needs to be evaluated. The aim of this study is to assess the test–retest reliability of these parameters in the specific case of fatigue detection. MethodForty participants performed two sessions of fast strokes handwriting (simple strokes, triangles, horizontal and vertical oscillations) on a tablet placed at shoulder’s height. Reliability was assessed using the intraclass correlation coefficient (ICC), their relative standard error of measurement (SEM) and coefficient of variation. The minimal detectable change was also reported.Findings: In general, a moderate to excellent reliability was denoted in the main parameters of each test (ICC: 0.54–0.91). The parameters related to shoulder fatigue detection had good to excellent reliability (ICC: 0.77–0.90) with low SEM (SEM: 4.75–6.99%). ConclusionMost of the parameters have good test–retest reliability, and the setup seems adequate for shoulder fatigue detection.

Crushing characteristics of different minerals by cylindrical ball mill in cascading motion state

During the grinding process of the impact and abrasion actions synchronously coexist and continuously occur, the two actions may exert forces in different areas and transform to each other periodically. So it is difficult to characterize the respective crushing characteristics of the impact and abrasion actions. Based on the kinematics theory of grinding media, to ensure the grinding medium to be in cascading motion state in which minerals are crushed by only abrasion action of medium, to investigate the crushing characteristics of three kinds of minerals of quartz, pyrrhotite, and pyrite. Moreover, the difference in the ability to resist the crushing in the grinding process and the influence of feed sizes on the crushing were investigated by analyzing and comparing the breakage rate of the different minerals and the yield of specific product size - t 10 value under different test conditions. The research results indicated that the grinding resistance of quartz is the strongest, followed by pyrite and pyrrhotite. Besides, a smaller feed size resulted in a more grinding and crushing effect on the minerals. Therefore, during production, the grinding system should be adjusted according to the change in the material property to prevent over-grinding.

Sit-to-Stand Test for Neurodegenerative Diseases Video Classification

In this extended version of this paper, an automatic video diagnosis system for dementia classification is presented. Starting from video recordings of patients and control subjects, performing sit-to-stand test, the designed system is capable of extracting relevant patterns for binary discern patients with dementia from healthy subjects. The original system achieved an accuracy 0.808 by using the rigorous inter-patient separation scheme especially suited for medical purposes. This separation scheme provides the use of some people for training and others, different, people for testing. The implementation of features from the kinematic theory of rapid human movement and its sigma-lognormal model together with classic features increased the overall accuracy of the system to 0.947 F1 score. In addition, multi-class classification was performed with the aim of classifying neurodegenerative disease severities. This work is an original and pioneering work on sit-to-stand video classification for neurodegenerative diseases, its novelties are on phases segmentation, experimental setup and the application of kinematic theory of rapid human movements to sit-to-stand videos for neurodegenerative disease assessment.