Three-dimensional Alignment of the Upper Extremity in the Standing Neutral Position in Healthy Subjects

Background: Though alignment of the spine and lower extremities in the standing neutral position has been evaluated, a few studies evaluating the alignment of the upper extremities have also been made. This study assessed the normal alignment of the upper extremities in the standing neutral position and clarified the three-dimensional angular rotations of the upper extremity joints.Methods: Computed tomography (CT) images of 158 upper extremities from 79 healthy volunteers were prospectively acquired in the standing neutral position using an upright CT scanner. Three-dimensional coordinate systems of the thorax, scapula, humerus, and forearm were designated, and three-dimensional angular rotations of the scapulothoracic, glenohumeral, and elbow joints were calculated.Results: The mean angle of the scapulothoracic joint was 8.5° ± 5.9° of upward rotation, 28.7° ± 5.9° of internal rotation, and 7.9° ± 5.2° of anterior inclination. The mean angle of the glenohumeral joint was 4.4° ± 5.9° of abduction, 9.4° ± 12.3° of internal rotation, and 0.3° ± 4.4° of extension. The mean angle of the elbow joint was 9.6° ± 3.7° of valgus, 88.8° ± 14.3° of pronation, and 15.4° ± 4.2° of flexion. Correlations in angular rotation values were found, and interactions for keeping the upper extremities in a neutral position were observed.Conclusions: This study clarified the three-dimensional angular rotation of upper extremity joints in the standing neutral position using an upright CT scanner. Our results may provide important insights for the functional evaluation of upper extremity alignment.

Experimental and Numerical Studies on Fluid–Structure Interaction for Underwater Drop of a Stone-Breaking Crusher

There are many methods for crushing seabed rock such as a using a free-falling crusher, blasting, and chemical liquid expansion. Blasting and chemical liquid expansion can lead to environmental destruction, noise pollution, and civil complaints. Therefore, a free-falling crusher is generally recommended for use. Understanding the characteristics of a crusher in water and the impact force on the ground is helpful for designing a crusher and dredge work. In this study, drop tests of 50 and 70 ton crusher models that were scaled down by 15 times were investigated. The tests were conducted in a water basin by the Research Institute of Medium and Small Shipbuilding (RIMS) in Korea. Four water depths were considered with different falling locations: water surface and air. Moreover, a numerical study on Fluid–Structure Interaction (FSI) analysis for a free-falling crusher was conducted by applying the Arbitrary Lagrangian–Eulerian (ALE) element and the Grüneisen Equation of State (EoS) to fluid models. The crusher and ground were modeled as Lagrangian elements to estimate the impact force on the ground. Before comparing the crusher model, a free-falling sphere model was used to develop FSI technologies by comparing past Computational Fluid Dynamics (CFD) and experimental results. Moreover, the recommended mesh size and fluid domain for FSI analysis are provided to achieve good results via convergence tests. Comparison between experimental and numerical methods demonstrated a similar tendency such that impact force increased at a higher depth. Certain numerical results agree with average values of experimental results; however, multiple numerical cases exhibit a moderate difference. This is because of angular rotation between the crusher and ground when the crusher hits the ground during experiments.

Circular Complementary Split Ring Resonator Rotation for Linear Array Millimeter Wave Microstrip Patch Antenna

This paper proposes multiple linear array millimeter wave MPAs that could operate at various frequencies depending on the angular rotation of the CSRR structure. The main contribution of this work is the range of frequencies of the linear array MPA found when the position of the CSRR structure is changed angularly. This is achieved by positioning the CSRR structure on the ground plane of the MPA and rotate it to an incremental of 22.5°. Computer Simulation Technology software is used to simulate the antenna designs. The performance of the antenna is evaluated against the single element millimeter wave MPA with similar angular rotation to the CSRR structure. The reflection coefficient graph shows at 0° rotation, the antenna has dual band performance at 26 GHz and 28 GHz. At 22.5° and 45° CSRR structure rotation, the antenna shows triple band performance with different operational frequencies and different polarization depending on the frequencies. Finally, at 67.5° CSRR structure rotation, the antenna now is operational only at 20 GHz frequency with horizontal polarization performance. Plus, the results between the single element MPA with circular CSSRR and the linear array MPA with circular CSRR shows similar behavior in which the rotation of the CSRR did not affect the antenna differently even with an increase of the number of elements. The millimeter wave MPA with CSRR angular rotation can be utilized in various applications as it covers multiple frequencies depending on the angle of rotation of the CSRR structure.

Mathematical modeling of mechanical properties of vibro-centrifuged fiber-reinforced concrete of variatropic structure

Today, one of the most relevant areas in the construction industry, linked to the requirements and provisions of the Strategy of Scientific and Technological Development, and in accordance with the priority areas of science and technology development, is the development and improvement of low-material, low-energy and low - resource-intensive technologies for the manufacture of concrete and reinforced concrete products and structures. In this regard, the technology of vibrocentrifugation, which allows to obtain concrete with an improved variatropic structure, is quite promising. In this work, the influence of the design parameters of the technological equipment and the parameters of the centrifugation modes on the integral strength characteristics of vibrocentrifugated fiber concrete was evaluated. In total, 13 samples of the annular section were manufactured and tested. Calculations of the integral strength characteristics of vibrocentrifugated fiber concrete depending on the height of the technological protrusions of the clamps and the angular rotation speed were performed by the method of orthogonal composite planning of the 2nd order using the MathCAD program. The mathematical method of planning the experiment is aimed at creating mathematical empirical models that determine the influence of the incoming variable factors on the strength characteristics. Thus, according to the results of experimental studies, the optimal height of the technological protrusions and the angular speed of rotation were determined. Thus, further regulation of technological factors in the manufacture of vibrocentrifugated products and structures will allow us to obtain the most effective ring-section structures with enhanced variatropy.

2D Omni-Directional Wireless Power Transfer Modeling for Unmanned Aerial Vehicles with Noncollaborative Charging System Control

Wireless power transfer (WPT) has been extensively studied from various aspects such as far field and near field, operating frequency, coil design, matched capacitance values, misaligned locations of transmitting and receiving coils, distance variance between them, target loads in the specific locations, environment, and operating conditions. This is due to the usefulness of WPT technology in many applications, including the revolutionary method of auto-recharging of unmanned aerial vehicles (UAVs). This paper presents analytical modeling of a WPT-link with two orthogonal transmitting coils arranged to produce an omnidirectional magnetic field suitable for charging a moving rotating load, maximizing energy transfer without any feedback from the receiving end. To achieve a suitable 2D WPT simulation system, as well as an accurate control design, the mutual coupling values in terms of receiver angular rotation are simulated using Ansys software. Power transfer is maximized by using extremum seeking control (ESC), making use of the input power as an objective function with specific parameter values that represent the WPT model to obtain the results. The results shown are those of the input power transmitted by the transmitting-end coils to a load of an orbiting mobile UAV. Based on the simulation results, the controller can achieve maximum power transfer in 100 µs of duration when the speed of the UAV is close to 314 rad/s.

Impact of a Vibrotactile Belt on Emotionally Challenging Everyday Situations of the Blind

Spatial orientation and navigation depend primarily on vision. Blind people lack this critical source of information. To facilitate wayfinding and to increase the feeling of safety for these people, the “feelSpace belt” was developed. The belt signals magnetic north as a fixed reference frame via vibrotactile stimulation. This study investigates the effect of the belt on typical orientation and navigation tasks and evaluates the emotional impact. Eleven blind subjects wore the belt daily for seven weeks. Before, during and after the study period, they filled in questionnaires to document their experiences. A small sub-group of the subjects took part in behavioural experiments before and after four weeks of training, i.e., a straight-line walking task to evaluate the belt’s effect on keeping a straight heading, an angular rotation task to examine effects on egocentric orientation, and a triangle completion navigation task to test the ability to take shortcuts. The belt reduced subjective discomfort and increased confidence during navigation. Additionally, the participants felt safer wearing the belt in various outdoor situations. Furthermore, the behavioural tasks point towards an intuitive comprehension of the belt. Altogether, the blind participants benefited from the vibrotactile belt as an assistive technology in challenging everyday situations.

Soft Elastomeric Capacitor for Angular Rotation Sensing in Steel Components

The authors have previously proposed corrugated soft elastomeric capacitors (cSEC) to create ultra compliant scalable strain gauges. The cSEC technology has been successfully demonstrated in engineering and biomechanical applications for in-plane strain measurements. This study extends work on the cSEC to evaluate its performance at measuring angular rotation when installed folded at the junction of two plates. The objective is to characterize the sensor’s electromechanical behavior anticipating applications to the monitoring of welded connections in steel components. To do so, an electromechanical model that maps the cSEC signal to bending strain induced by angular rotation is derived and adjusted using a validated finite element model. Given the difficulty in mapping strain measurements to rotation, an algorithm termed angular rotation index (ARI) is formulated to link measurements to angular rotation directly. Experimental work is conducted on a hollow structural section (HSS) steel specimen equipped with cSECs subjected to compression to generate angular rotations at the corners within the cross-section. Results confirm that the cSEC is capable of tracking angular rotation-induced bending strain linearly, however with accuracy levels significantly lower than found over flat configurations. Nevertheless, measurements were mapped to angular rotations using the ARI, and it was found that the ARI mapped linearly to the angle of rotation, with an accuracy of 0.416∘.

Analytical Solution of the Dynamics Equations for a Wave Solid-State Gyroscope Using the Angular Rate Linear Approximation

The exact solution is provided of the dynamics equation for an elastic inextensible ring being the basic model of a wave solid-state gyroscope with the linear law of the base angular rotation rate alteration. This solution is presented in terms of the parabolic cylinder functions (Weber function). Asymptotic approximations are used in the device certain operating modes. On the basis of the solution obtained, the analytical solution to the equation of the ring dynamics in case of piecewise linear approximation of the angular rate arbitrary profile on a time grid is derived. This significantly expands the class of angular rate dependences, for which the solution could be written down analytically. Earlier, in addition to the simplest case of constant angular rate, solutions were obtained for angular rate varying according to the square root law with time (Airy function), as well as according to the harmonic law (Mathieu function). Error dependence of such approximation on the discretization step in time is estimated numerically. Results obtained make it possible to reduce the number of operations, when it is necessary to study long-term evolutions of the dynamic system oscillations, as well as to quantitatively and qualitatively control convergence of finite-difference schemes in solving dynamics equations for a wave solid-state gyroscope with the ring resonator

Migration Behavior of Low-Density Particles in Lab-on-a-Disc Devices: Effect of Walls

The effect of the lateral walls of a Lab-On-a-Disc device on the dynamics of a model system of particles with a density lower than that of the solvent (modelling parasites eggs) is analyzed theoretically and experimentally. In the absence of lateral walls, a particle always moves in the direction of the centrifugal force, while its trajectory is deflected in the tangential direction by the inertial Coriolis and Euler forces. Lateral walls, depending on the angle forming with the radial direction, can guide the particle either in the same or in the opposite direction to the centrifugal force, thus resulting in unusual particle trajectories including zig-zag or backwards particle motion. The effect is pronounced in the case of short operation times when the acceleration of the angular rotation, and thus the Euler force, is considerable. The predicted unusual motion is demonstrated by numerically solving the equation of motion in the presence of lateral walls and verified in the experiment with particles of density lower than that of the solvent. Our analysis is useful for design and operational considerations of Lab-On-a-Disc devices aiming for or involving (bio)particle handling.