Rotation Mechanism Research Articles

A New Coding System for the Identification of Left Ventricular Rotation Patterns and Their Relevance to Myocardial Function

Rotational mechanics is a fundamental determinant of left ventricular ejection fraction (LVEF). The coding system currently employed in clinical practice does not distinguish between rotational patterns. We propose an alternative coding system that makes possible to identify the rotational pattern of the LV and relate it to myocardial function. Echocardiographic images were used to generate speckle tracking-derived transmural global longitudinal strain (tGLS) and rotational parameters. The existence of twist (basal and apical rotations in opposite directions) is expressed as a rotational gradient with a positive value that is the sum of the basal and apical rotation angles. Conversely, when there is rigid rotation (basal and apical rotations in the same direction) the resulting gradient is assigned a negative value that is the subtraction between the two rotation angles. The rotational patterns were evaluated in 87 healthy subjects and 248 patients with LV hypertrophy (LVH) and contrasted with their myocardial function. Our approach allowed us to distinguish between the different rotational patterns. Twist pattern was present in healthy controls and 104 patients with LVH and normal myocardial function (tGLS ≥ 17%, both). Among 144 patients with LVH and myocardial dysfunction (tGLS < 17%), twist was detected in 83.3% and rigid rotation in 16.7%. LVEF was < 50% in 34.7%, and all patients with rigid rotation had a LVEF < 50%. The gradient rotational values showed a close relationship with LVEF (r = 0.73; p < 0.001). The proposed coding system allows us to identify the rotational patterns of the LV and to relate their values with LVEF.

Two-Dimensional Ultrathin Fe3Sn2 Kagome Metal with Defect-Dependent Magnetic Property.

Two-dimensional (2D) Fe3Sn2, which is a room-temperature ferromagnetic kagome metal, has potential applications in spintronic devices. However, the systematic synthesis and magnetic study of 2D Fe3Sn2 single crystals have rarely been reported. Here we have synthesized 2D hexagonal and triangular Fe3Sn2 nanosheets by controlling the amount of FeCl2 precursors in the chemical vapor deposition (CVD) method. It is found that the hexagonal Fe3Sn2 nanosheets exist with Fe vacancy defects and show no obvious coercivity. While the triangular Fe3Sn2 nanosheet has obvious hysteresis loops at room temperature, its coercivity first increases and then remains stable with an increase in temperature, which should result from the competition of the thermal activation mechanism and spin direction rotation mechanism. A first-principles calculation study shows that the Fe vacancy defects in Fe3Sn2 can increase the distances between Fe atoms and weaken the ferromagnetism of Fe3Sn2. The resulting 2D Fe3Sn2 nanosheets provide a new choice for spintronic devices.

Three-dimensional tunnel face stability using a new heterogeneous dynamic filter cake

In slurry-shield tunnelling, a heterogeneous dynamic filter cake occurs due to the interaction between slurry infiltrating and tool cutting, whose influence on tunnel face stability is not fully plumbed. Thus, a numerically based-limit analysis framework is proposed to assess the tunnel face stability considering a heterogeneous dynamic filter cake. The numerical model with a heterogeneous dynamic filter cake, which has spatio-temporally variable permeability coefficients according to cutter layouts, is built for solving a transient seepage flow. Numerically obtained seepage flow results are further incorporated into the 3D rotational failure mechanism, so as to give an upper-bound estimation on the tunnel face safety factor and the slurry pressure transfer efficiency. The proposed method is validated by comparing with previous studies regarding the slurry pressure drop, slurry pressure transfer efficiency, and tunnel face safety factors. Parametric analyses are performed to examine the excess pore pressure distributions at the filter cake-soil interface, and discuss the influences of cutterhead rotation and excess slurry pressures on the tunnel face stability. The results show that the defined three-dimensional pressure transfer efficiency is between the one-dimensional and the two-dimensional solutions published previously; the tunnel face stability reduces as cutterhead rotating and finally reaches a dynamic equilibrium state.

Mechanism of principal stress rotation and deformation failure behavior induced by excavation in roadways

The failure modes of rock after roadway excavation are diverse and complex. A comprehensive investigation of the internal stress field and the rotation behavior of the stress axis in roadways is essential for elucidating the mechanism of roadway failure. This study aimed to examine the spatial relationship between roadways and stress fields. The law of stress axis rotation under three-dimensional (3D) stress has been extensively studied. A stress model of roadways in the spatial stress field was established, and the far-field stress state at different spatial positions of the roadways was analyzed. A mechanical model of roadways under a 3D stress state was established using far-field stress solutions as boundary conditions. The distribution of principal stresses σ1, σ2 and σ3 around the roadways and the variation of the stress principal axis were solved. It was found that the stability boundary of the stress principal axis exhibits hysteresis when compared with that of the principal stress magnitudes. A numerical analysis model for spatial roadways was established to validate the distribution of principal stress and the mechanism of principal axis rotation. Research has demonstrated that the stress axis undergoes varying degrees of spatial rotation in different orientations and radial depths. Based on the distribution of principal stress and the rotation law of the stress principal axis, the entire evolution mechanism of the two stress adjustments to form the final failure form after roadway excavation has been revealed. The on-site detection results also corroborate the findings presented in this paper. The results provide a basis for the analysis of the failure mechanism under a 3D stress state.

Kinematic Modeling and Performance Analysis of a 5-DoF Robot for Welding Applications

Robotic manipulators are critical for industrial automation, boosting productivity, quality, and safety in various production applications. Key factors like the payload, speed, accuracy, and reach define robot performance. Optimizing these factors is crucial for future robot applications across diverse fields. While 6-Degrees-of-Freedom (DoF)-articulated robots are popular due to their diverse applications, this research proposes a novel 5-DoF robot design for industrial automation, featuring a combination of three prismatic and two revolute (2R) joints, and analyzes its workspace. The proposed techno-economically efficient design offers control over the robot manipulator to achieve any reachable position and orientation within its workspace, replacing traditional 6-DoF robots. The kinematic model integrates both parallel and serial manipulator principles, combining a Cartesian mechanism with rotational mechanisms. Simulations demonstrate the end effector’s flexibility for tasks like welding, additive manufacturing, and material inspections, achieving the desired position and orientation. The research encompasses the design of linear and rotational actuators, kinematic modeling, Human–Machine Interface (HMI) development, and welding application integration. The developed robot demonstrates a superior performance and user-friendliness in welding. The experimental work validates the design’s optimized joint trajectories, efficient power usage, singularity avoidance, easy access in application areas, and reduced costs due to fewer actuators.

A Zoom Microwave Metalens With Mechanical Rotation

A Zoom Microwave Metalens With Mechanical Rotation

Design of millimeter wave broadband polarization reconfigurable horn antenna based on elliptical waveguide polarizer

AbstractA broadband polarized reconfigurable horn antenna for K‐band and Ka‐band is designed using a circular polarizer in the form of an elliptical waveguide and a circular waveguide flange based on a gap structure. The designed noncontact circular waveguide flange with gap structure can switch the antenna excitation signal to different modes of electromagnetic waves by mechanical rotation. When excited by different modes of electromagnetic waves, the designed elliptical waveguide circular polarizer can switch between linear polarization, left‐handed circular polarization, and right‐handed circular polarization. The antenna is analyzed in principle, modeled and simulated, and processed by three‐dimensional printing process. The measured results show that S11 ≤ −15dB, axial ratio ≤ 3 dB, gain ≥14 dBi in 37.8% relative bandwidth range (22.5–33 GHz). The proposed antenna is broadband, multipolar, and reconfigurable, which makes it have broad application prospects in the field of satellite communication and millimeter‐wave communication.

A pendulum based frequency-up conversion mechanism for vibrational energy harvesting in low-speed rotary structures

Motivated to run a self-powering monitoring sensor on a wind turbine blade, this paper proposes a pendulum based frequency-up converter that effectively captures a low-speed mechanical rotation into high-frequency vibration of a piezoelectric cantilever beam. A system of governing equations for the proposed concept is developed to describe the motion of the pendulum, the vibration of the beam, and the voltage output of the harvester. Design optimization is performed to improve the power generation performance, and the simulation results are verified experimentally. We demonstrate the improved power density from the proposed concept compared to the disk driven frequency-up converters.

One-shot measurement of birefringence by radial analysis

Due to complexity and bulky configuration of conventionally mechanical rotation approaches, a more convenient approach is to measure the birefringence effect (phase retardation and fast axis) by nano-fabricated spatial devices. Previous literature introduced radially-polarized illumination and eliminated the need for rotation mechanics in the illumination optics but still required rotation devices in the analyzer part. This work aims to achieve a compact and one-shot birefringence measurement by introducing spatial concepts in both the modulator and analyzer. By proposing a novel birefringence measurement by the combination of radial illumination and radial analyzer, this work is the first time to integrate no-mechanical motion and one-shot birefringence measurement in a single light path. What’s more, we are the first to introduce Fourier analysis in birefringence measurement, replacing the previous average intensity calculation, which is easily influenced by light source fluctuations. Based on our one-shot & non-mechanical measurement design and Fourier analysis algorithm, our birefringence measurement achieved very stable phase retardation measurement (standard deviation < 0.3°) and high accuracy fast axis measurement (average absolute error < 0.04°).

Coexistence of dual wing–wake interaction mechanisms during the rapid rotation of flapping wings

Insects flip their wings around each stroke reversal and may enhance lift in the early stage of a half-stroke. The possible lift-enhancing mechanism of this rapid wing rotation and its strong connection with wake vortices are still underexplored, especially when unsteady leading-edge vortex (LEV) behaviours occur. Here, we numerically studied the lift generation and underlying vorticity dynamics during the rapid rotation of a low aspect ratio flapping wing at a Reynolds number ( ${\textit {Re}}$ ) of 1500. Our findings prove that when the outboard LEV breaks down, an advanced rotation can still enhance the lift in the early stage of a half-stroke, which originates from an interaction with the breakdown vortex in the outboard region. This interaction, named the breakdown-vortex jet mechanism, results in a jet and thus a higher pressure on the upwind surface, including a stronger wingtip suction force on the leeward surface. Although the stable LEV within the mid-span retains its growth and location during an advanced rotation, it can be detrimental to lift enhancement as it moves underneath the wing. Therefore, for a flapping wing at ${\textit {Re}}\sim 10^3$ , the interactions with stable and breakdown leading-edge vortices lead to the single-vortex suction and breakdown-vortex jet mechanisms, respectively. In other words, the contribution of wing–wake interaction depends on the spanwise location. The current work also implies the importance of wing kinematics to this wing–wake interaction in flapping wings, and provides an alternative perspective for understanding this complex flow phenomenon at ${\textit {Re}}\sim 10^3$ .

Global left ventricular strains and left atrial volumes are not associated in healthy adults – Detailed analysis from the three-dimensional speckle-tracking echocardiographic MAGYAR-Healthy Study

IntroductionDuring the heart cycle, left ventricular (LV) contractility is characterized by complex deformation and rotational mechanics, resulting in LV ejection. The present study seeks to expand our knowledge by examining dependence of LV strains representing LV deformation on left atrial (LA) volumes in healthy circumstances. Therefore, the aim of this study was to evaluate the associations between LA volumes and LV strains as assessed simultaneously by three-dimensional speckle-tracking echocardiography (3DSTE) in normal healthy adults. MethodsThe present study consisted of 302 healthy adults, but according to exclusion criteria, 137 subjects were excluded due to inferior image quality. The final population comprised 165 individuals (mean age: 33.1 ± 12.3 years, 75 males) who were voluntarily recruited for screening. Two-dimensional echocardiography extended with 3DSTE was performed in all subjects for detailed LV/LA analysis. ResultsOverall feasibility for simultaneous assessment of LV strains and LA volumes proved to be 55 % with excellent intra- and interobserver correlations. All global LV strains were similar, regardless of the LA volumes examined. All LA volumes and volume-based functional properties respecting the cardiac cycle were similar, regardless the global LV strains examined. ConclusionsLV strains and LA volumes can be simultaneously assessed by 3DSTE. Global LV strains and LA volumes are not associated in healthy adults.

Polarity-driven three-dimensional spontaneous rotation of a cell doublet

Mechanical interactions between cells play a fundamental role in the self-organization of organisms. How these interactions drive coordinated cell movement in three dimensions remains unclear. Here we report that cell doublets embedded in a three-dimensional extracellular matrix undergo spontaneous rotations. We investigate the rotation mechanism and find that it is driven by a polarized distribution of myosin within cell cortices. The mismatched orientation of this polarized distribution breaks the doublet mirror symmetry. In addition, cells adhere at their interface through adherens junctions and with the extracellular matrix through focal contacts near myosin clusters. We use a physical theory describing the doublet as two interacting active surfaces to show that rotation is driven by myosin-generated gradients of active tension whose profiles are dictated by interacting cell polarity axes. We also show that three-dimensional shape symmetries are related to broken symmetries of the myosin distribution in cortices. To test for the rotation mechanism, we suppress myosin clusters using laser ablation and generate new myosin clusters by optogenetics. Our work clarifies how polarity-oriented active mechanical forces drive collective cell motion in three dimensions.

Rapid and Sensitive Biosensing of Salmonella Using Mechanical Step Rotation and Gold@platinum Nanozymatic Amplification

Rapid and Sensitive Biosensing of Salmonella Using Mechanical Step Rotation and Gold@platinum Nanozymatic Amplification

Origami-inspire quasi-zero stiffness structure for flexible low-frequency vibration isolation

As an emerging technology, origami exhibits rich nonlinear static and dynamic properties. However, simulating creases remains a key challenge hindering practice application, especially for volumetric (deformable) origami. Inspired by the bistable behavior and axial-rotational coupling mechanism of triangulated cylindrical origami (TCO), this paper proposes a novel combined truss-spring structure with additional inertial mechanism (TCTS-RIM) for low-frequency vibration isolation. Unlike pure TCO, the TCTS-RIM uses elastic linkages to simulate all creases and modifies crease positions, enhancing physical realization in engineering applications and offering tunable stiffness and inertia on demand. Static analysis shows the modified truss-spring structure in TCTS-RIM has superior quasi-linear negative stiffness compared to pure TCO, which enables a very wide quasi-zero stiffness (QZS) range via linear spring compensation. The wide QZS range for different loads can be realized by setting appropriate structural parameters. From system dynamic equations, nonlinear inertia, nonlinear quadratic force, and nonlinear damping due to RIM are identified and discussed. The Alternating frequency–time harmonic balance method is used to obtain the displacement transmissibility, and its parametric influencing investigations verify that the proposed TCTS-RIM has excellent low-frequency vibration isolation performance and rich tunability. Comparative discussions show the wide QZS range significantly reduces the resonance frequency, broadens the isolation frequency band, and yields superior dynamic performance versus pure TCO isolators. Moreover, equivalent mass, anti-resonance and softening behavior induced by the rotational inertia mechanism further enhance low-frequency vibration isolation performance. An experimental prototype is built, and experimental results validate the correctness of the theoretical analyses. This work presents a simple mechanical implementation of volumetric origami, which may progress the engineering applications of origami and provide a viable approach to low-frequency vibration control.

CHIRAL SWITCHING CONTROL OF PHARMACEUTICAL SUBSTANCES

Objective: The aim of this study was to demonstrate that chiral switching should be recognized as a widespread phenomenon that extends beyond the production of pure enantiomeric drugs. Methods: To investigate the optical activity of substances from various chemical classes, enantiomers of chiral compounds (Sigma-Aldrich, USA) were chosen: valine and its racemic form (D-valine, L-valine, and racemic valine with optical purity ≥ 99%), L-ascorbic acid (content ≥ 99%), carbohydrates (D-glucose, D-galactose, L-galactose, contents ≥ 99.5%). Solutions were prepared using deuterium-depleted water (DDW–"light" water, D/H=4 ppm), natural deionized high-ohmic water (BD, D/H=140 ppm), and heavy water (99.9% D2O; Sigma-Aldrich). Optical activity was measured using the Atago POL-1/2 polarimeter. Results: One of the components in the racemic medication mixture can act as an inert agent, exhibit toxicity, or undergo undesirable biotransformation mechanisms, resulting in the formation of products with unknown properties. It has been established that a change in the deuterium/protium (D/H) ratio in water leads to a change in the equilibrium and kinetic characteristics of optically active compounds across various chemical classes, such as amino acids, carboxylic acids, and carbohydrates. An inequality was observed in the absolute values of the optical rotation of the L-and D-isomers of valine and galactose, depending on the D/H isotope ratio. The impact of chiral water clusters on optical rotation accounts for the sudden shift in the specific rotation of dilute solutions (less than 0.5%) of L-ascorbic acid in water, based on the D/H ratio. The influence of the isotopic composition of water was confirmed by studying the temperature-dependent mutarotation kinetics of D-glucose and L-and D-galactose in Arrhenius coordinates. The mutarotation process in natural high-resistivity water is characterized by an activation energy (Ea) of 40.8±1.4 kJ mol-1, while in deuterium-depleted water, Ea = 63.6±3.5 kJ mol-1. This results in a kinetic isotope effect for deuterium (KIED) of 1.6. Conclusion: Methodological approaches have been developed to control chiral switching based on the isotopic composition of water in vivo and in vitro. The study of changes in the optical activity of hierarchical structures in the human body, the influence of solvent properties on the mechanisms of optical rotation, as well as the use of KIED values, can be utilized to monitor various chiral transitions in vitro and living organisms.

Heat absorption/release efficiency betterment of phase change material inside a shell-and-tube latent heat storage system under six different conditions of tube and fins

Researchers are exploring innovative solutions for thermal energy storage to address the challenges posed by intermittent renewable sources, enhance energy efficiency, and contribute to the global shift towards cleaner and more sustainable energy practices. In the pursuit of an optimal system to improve the heat release/absorption efficiency of phase change materials (PCMs), a unique shell and tube latent heat storage system with four rectangular fins was designed. The melting and solidification behaviors of the material in this device were examined by manipulating the tube's position within the shell and fins around the tube. Six different cases were considered such as case A (tube in the center of the shell), case B (tube at the top of the shell), case C (tube at the bottom of the shell), case D (tube in the center of the shell with fins on its sides), case E (tube at the top of the shell with fins located in its bottom section), and case F (tube at the bottom of the shell with fins located in its top section). Cases D and E were the best options for absorbing and releasing heat in the shortest time. However, it should be noted that case F was faster during the melting process and dropped behind in the final stages. The authors proposed that if achieving a balanced result without incurring additional costs is essential, case D is a suitable option since it offers reasonable performance in melting and solidification processes. However, suppose researchers and developers of energy storage systems are seeking higher performances where heat absorption and release occur much more rapidly. In that case, it is suggested to construct one of the cases, E or F, and implement a rotational mechanism to enable access to the other case. Based on the outcomes, cases D and F needed 6235 s and 7552 s, respectively, to fully melt. While all cases even required more than 3 h to solidify 80 % of the PCM. The complete melting speed of Case F is 21.12 % faster than that of Case D. Additionally, the time required for 50 % solidification is 14.79 % faster for Case E compared to Case D. During 3 h, this system could absorb 1172 kJ of energy (cases D and F) and release 893 kJ of energy (cases D and E).

A methodological assessment to determine the frequency response of utility-scale deloaded PV under variability

Replacing the traditional synchronous generators with photovoltaic systems (PV) causes an overall reduction in grid inertia. Further, as the newly installed PV plants do not require any rotational mechanism to generate active power, they are not also able to ramp the generation during contingency situations leading to frequency collapse of the grid. To deal with this issue, a portion of peak solar generation can be kept as deloaded reserve which can be released during emergency conditions emulating the conventional system. However, the allocation of deloading as a percentage of PV power can introduce randomness on the expected support as the dispatched PV power varies depending on the irradiance and temperature values. Therefore, it is essential to accurately estimate the frequency support of a given deloading percentage to maintain frequency stability considering PV variability. In this regard, this study presents a generalized approach to determine the frequency response of deloaded support under utility-scale PV integration. To achieve this, linear and quadratic regression are employed to establish a mathematical correlation using the data derived from dynamic simulations conducted on a modified IEEE 39 bus grid at various PV penetration levels. The obtained results indicate a minimum generation of PV power is required to prevent under-frequency load shedding for a fixed deloading percentage. These findings are later verified by comparing them with two other techniques - battery energy storage system and synchronous condenser based on the simulated results achieved from DIgSILENT PowerFactory software. Moreover, this paper provides insights into how this required minimum PV generation changes with the variation in sanctioned deloading percentage. This can aid the grid designers to allow proper deloaded operation depending on the environmental condition.

Design and Testing of a Compliant ZTTΘ Positional Adjustment System with Hybrid Amplification.

This article presents the design, analysis, and prototype testing of a four-degrees-of-freedom (4-DoFs) spatial pose adjustment system (SPAS) that achieves high-precision positioning with 4-DoFs (Z/Tip/Tilt/Θ). The system employs a piezoelectric-driven amplification mechanism that combines a bridge lever hybrid amplification mechanism, a double four-bar guide mechanism, and a multi-level lever symmetric rotation mechanism. By integrating these mechanisms, the system achieves low coupling, high stiffness, and wide stroke range. Analytical modeling and finite element analysis are employed to optimize geometric parameters. A prototype is fabricated, and its performance is verified through testing. The results indicate that the Z-direction feed microstroke is 327.37 μm, the yaw motion angle around the X and Y axes is 3.462 mrad, and the rotation motion angle around the Z axis is 12.684 mrad. The x-axis and y-axis motion magnification ratio can reach 7.43. Closed-loop decoupling control experiments for multiple-input-multiple-outputs (MIMO) systems using inverse kinematics and proportional-integral-derivative feedback controllers were conducted. The results show that the Z-direction positioning accuracy is ±100 nm, the X and Y axis yaw motion accuracy is ±2 μrad, and the Z-axis rotation accuracy is ±25 μrad. Due to the ZTTΘ mechanism, the design proved to be feasible and advantageous, demonstrating its potential for precision machining and micro-nano manipulation.

Single-Image Super-Resolution Method for Rotating Synthetic Aperture System Using Masking Mechanism

The emerging technology of rotating synthetic aperture (RSA) presents a promising solution for the development of lightweight, large-aperture, and high-resolution optical remote sensing systems in geostationary orbit. However, the rectangular shape of the primary mirror and the distinctive imaging mechanism involving the continuous rotation of the mirror lead to a pronounced decline in image resolution along the shorter side of the rectangle compared to the longer side. The resolution also exhibits periodic time-varying characteristics. To address these limitations and enhance image quality, we begin by analyzing the imaging mechanism of the RSA system. Subsequently, we propose a single-image super-resolution method that utilizes a rotated varied-size window attention mechanism instead of full attention, based on the Vision Transformer architecture. We employ a two-stage training methodology for the network, where we pre-train it on images masked with stripe-shaped masks along the shorter side of the rectangular pupil. Following that, we fine-tune the network using unmasked images. Through the strip-wise mask sampling strategy, this two-stage training approach effectively circumvents the interference of lower confidence (clarity) information and outperforms training the network from scratch using the unmasked degraded images. Our digital simulation and semi-physical imaging experiments demonstrate that the proposed method achieves satisfactory performance. This work establishes a valuable reference for future space applications of the RSA system.

Numerical investigation and optimization of the melting performance of latent heat thermal energy storage unit strengthened by graded metal foam and mechanical rotation

In this paper, a combined passive graded metal foam and active mechanical rotation strategy is proposed to simultaneously solve the problem of slow melting rate and non-uniform phase change problem of the latent heat thermal energy storage (LHTES) technology. The enthalpy-porosity method and fixed grid structure are employed to numerically investigate the effects of porosity range, the number of graded layers, and the rotational angular velocity. Moreover, the response surface method (RSM) is further selected to optimize the structural parameters and obtain the function of melting performance and various factors. The result shows that there is an optimal porosity range and the total melting time decreases first and then increases with the increase of porosity range. When the porosity range is 12 % and the graded layer is three, it can shorten the melting time by 35.54 % and increase the thermal energy storage rate (TESR) by 51.57 %. In addition, the melting performance is gradually improved as the number of graded layers increases. The strengthening effect of graded metal foam with just four layers is close to that of the maximum layers considered in this paper. The trend of the influence of rotation speed on the melting performance of the LHTES unit is consistent with the porosity range, indicating the existence of the optimal rotational speed. The RSM optimization structure, with a 14.969 % porosity range, 5-layer graded number, and 2.267 rpm rotational speed, shortens the melting time by 42.42 % and increases the TESR by 62.75 % compared with the stationary case with uniform metal foam. This work verifies the effectiveness of active rotation coupling with passive graded porous structures, which could provide a new strengthening approach to enhance LHTES.