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Abstract An abundance of degrees of freedom (DOF) exist when executing a countermovement jump (CMJ). This research aims to simplify the understanding of this complex system by comparing jump performance and independent functional DOF (fDOF) present in CMJs without (CMJNoArms) and with (CMJArms) an arm swing. Principal component analysis was used on 39 muscle forces and 15 3-dimensional joint contact forces obtained from kinematic and kinetic data, analyzed in FreeBody (a segment-based musculoskeletal model). Jump performance was greater in CMJArms with the increased ground contact time resulting in higher external (p = 0.012), hip (p

We present a new analytical solution to study the mechanical coupling on tidal‐induced head fluctuations in a coastal aquifer system. The conceptual model consists of two overlying confined units that extend infinitely under the sea. The proposed model assumes that the tidal fluctuations in the overlying aquifer are described by the classical equation derived by van der Kamp. For the underlying aquifer, a closed form analytical expression is derived by solving a boundary value problem that considers the loading effect produced by the overlying unit. The amplitude and phase lag of the underlying aquifer depend on both the specific storage and the thickness of the overlying unit. A parametric study shows that the mechanical coupling effect can be important for both large values of specific storage and thickness of the overlying aquifer. [ABSTRACT FROM AUTHOR]

An abundance of degrees of freedom (DOF) exist when executing a countermovement jump (CMJ). This research aims to simplify the understanding of this complex system by comparing jump performance and independent functional DOF (fDOF) present in CMJs without (CMJNoArms) and with (CMJArms) an arm swing. Principal component analysis was used on 39 muscle forces and 15 3-dimensional joint contact forces obtained from kinematic and kinetic data, analyzed in FreeBody (a segment-based musculoskeletal model). Jump performance was greater in CMJArms with the increased ground contact time resulting in higher external (p = 0.012), hip (p < 0.001) and ankle (p = 0.009) vertical impulses, and slower hip extension enhancing the proximal-to-distal joint extension strategy. This allowed the hip muscles to generate higher forces and greater time-normalized hip vertical impulse (p = 0.006). Three fDOF were found for the muscle forces and 3-dimensional joint contact forces during CMJNoArms, while four fDOF were present for CMJArms. This suggests that the underlying anatomy provides mechanical constraints during a CMJ, reducing the demand on the control system. The additional fDOF present in CMJArms suggests that the arms are not mechanically coupled with the lower extremity, resulting in additional variation within individual motor strategies. [ABSTRACT FROM AUTHOR]

The crustal material from central Tibet is extruded in a clockwise direction along a belt on the eastern plateau. In the inner arc region of the escaping belt, the absence of key and detailed 3‐D crustal resistivity structure hinders a comprehensive understanding of the dynamic processes of material escape in both the inner and outer arc regions. Here, we conducted magnetotelluric imaging and obtained the crustal 3‐D resistivity structure in Sanjiang area. The results reveal the presence of two branched high‐conductivity anomaly belts in the middle crust. Combining with other resistivity and velocity models, we speculated that crustal flow is widely distributed in the middle crust of the Chuan‐Dian block. The crustal flow in the Sanjiang area may connect to that in the outer arc region. The crustal flow in the eastern part is extensively continuous, causing decoupling and flowing that facilitate intense horizontal movements and deformation of the upper crust. In the western Sanjiang area, the upper crust is strongly coupled with the lithosphere beneath the decoupling layer, resulting in weaker horizontal deformation, and fewer larger earthquakes. The initially weak crustal zone in the eastern Tibet may have been caused by uplift of hot mantle material. The high heat flow associated with uplift of hot mantle material and the frictional heating caused by the horizontal movement of weakly coupled crust further facilitated the formation of crustal flow in the outer arc region. The branched crustal flow in the Sanjiang area may have flowed from the outer arc region of the escaping belt. Plain Language Summary: The crustal flow model can well explain the expansion of the Tibetan Plateau in the eastern margin of the plateau, and the high‐conductivity bodies in the middle‐lower crust may reflect the morphology of crustal flow. In the Sanjiang area of eastern Tibet, we used magnetotelluric data from 41 sites to discover branched high‐conductivity belts in the middle crust through 3‐D imaging, which are different from the extensively continuous high‐conductivity layer in the eastern part. They reveal the differences in the morphology of crustal flow between the inner and outer arc regions of the material escaping belt. The difference in the morphology of high‐conductivity structures leads to different degrees of crustal mechanical coupling, which in turn is related to surface strain rate, topography, and seismic activities. We speculate that crustal flow initially originated from the outer arc region and gradually developed toward the inner arc region. Key Points: 3‐D magnetotelluric imaging confirmed the presence of branched crustal flow in Sanjiang area, eastern Tibetan PlateauCrustal flow is widely in the middle crust of the North Chuan‐Dian block and its morphologies in eastern and western are differentThe branched crustal flow in the Sanjiang area may have flowed from the outer arc region of the escaping belt [ABSTRACT FROM AUTHOR]

The electromagnet module, as a fundamental component providing levitation force for maglev trains, plays a crucial role in ensuring the stability of train operation. However, vibrations can easily occur due to the mechanical coupling between the two suspension points of the electromagnet module. To reveal the inherent instability of the system and the coupling relationship between the state variables, a state-space equation that considers the mechanical coupling between the two suspension points is established. Furthermore, a differential control algorithm based on geometric feature transformation is proposed to mitigate the structural coupling vibration. Simulation experiments are conducted to compare the dynamic characteristics of the system before and after implementing the improvement algorithm under complex conditions. At the same time, the influence of control parameters on electromagnetic vibration was analyzed, focusing particularly on vibrations resulting from parameter mismatch, offering crucial insights for enhancing system stability. Additionally, suspension tests are carried out on the high-speed double bogie test platform in the Key Laboratory of Hunan Province to further validate the effectiveness of the proposed algorithm. The proposed control framework is both effective and concise, making it easy to implement in engineering applications. This research holds significant practical value in improving the stability of maglev trains. [ABSTRACT FROM AUTHOR]

The ability of cells to move in a mechanically coupled, coordinated manner, referred to as collective cell migration, is central to many developmental, physiological, and pathophysiological processes. Limited understanding of how mechanical forces and biochemical regulation interact to affect coupling has been a major obstacle to unravelling the underlying mechanisms. Focusing on the linker protein vinculin, we use a suite of Förster resonance energy transfer-based biosensors to probe its mechanical functions and biochemical regulation, revealing a switch that toggles vinculin between loadable and unloadable states. Perturbation of the switch causes covarying changes in cell speed and coordination, suggesting alteration of the friction within the system. Molecular scale modelling reveals that increasing levels of loadable vinculin increases friction, due to engagement of self-stabilizing catch bonds. Together, this work reveals a regulatory switch for controlling cell coupling and describes a paradigm for relating biochemical regulation, altered mechanical properties, and changes in cell behaviors. [ABSTRACT FROM AUTHOR]

A new model for a one-dimensional (1D) metamaterial model is formulated based on the couple stress theory. Different point groups of crystal will affect the mechanical couplings in the 1D metamaterial model. We find that when the material belongs to D2 point group, an unusual set of equations is decoupled from governing equations: axial force–torsion–warping (FTW) metamaterial model, which describes an unusual mechanical coupling that cannot occur in traditional materials. The deformation behaviors of the current model under a different axial force are analyzed by using the FTW metamaterial model. The numerical results show that the middle part of the current model has maximum torsional deformation when subjected to sine-type axial force. Since the end of the current model is fixed, the current model does not have compressional deformation globally. Moreover, when the current model is subjected to cosine-type axial force, the FTW coupling is successfully achieved. Then, we study a rod-like metamaterial model under an axial end force. The results show that the compressional deformation occurs at the free end, with a counterclockwise torsion. The current work provides guidance for the structural design and theoretical analysis of the rod-like metamaterial when using the couple stress theory. [ABSTRACT FROM AUTHOR]

The electromagnet module, as a fundamental component providing levitation force for maglev trains, plays a crucial role in ensuring the stability of train operation. However, vibrations can easily occur due to the mechanical coupling between the two suspension points of the electromagnet module. To reveal the inherent instability of the system and the coupling relationship between the state variables, a state-space equation that considers the mechanical coupling between the two suspension points is established. Furthermore, a differential control algorithm based on geometric feature transformation is proposed to mitigate the structural coupling vibration. Simulation experiments are conducted to compare the dynamic characteristics of the system before and after implementing the improvement algorithm under complex conditions. At the same time, the influence of control parameters on electromagnetic vibration was analyzed, focusing particularly on vibrations resulting from parameter mismatch, offering crucial insights for enhancing system stability. Additionally, suspension tests are carried out on the high-speed double bogie test platform in the Key Laboratory of Hunan Province to further validate the effectiveness of the proposed algorithm. The proposed control framework is both effective and concise, making it easy to implement in engineering applications. This research holds significant practical value in improving the stability of maglev trains.

Cells in vivo are surrounded by fibrous extracellular matrix (ECM), which can mediate the propagation of active cellular forces through stressed fiber bundles and regulate various biological processes. However, the mechanisms for multi‐cellular organization and collective dynamics induced by cell‐ECM mechanical couplings, which are crucial for the development of novel ECM‐based biomaterial for cell manipulation and biomechanical applications, remain poorly understood. Herein, the authors design an in vitro quasi‐3D experimental system and demonstrate a transition between spreading and aggregating in collective organizational behaviors of discrete multi‐cellular systems, induced by engineered ECM‐cell mechanical coupling, with the observed phenomena and underlying mechanisms differing fundamentally from those of cell monolayers. During the process of collective cell organization, the collagen substrate undergoes reconstruction into a dense fiber network structure, which is correlated with local cellular density and consistent with observed enhanced cells' motility; and the weakening of fiber bundle formation within the hydrogel reduces cells' movement. Moreover, cells can respond to the curvature and shape of the original cell population and form different aggregation patterns. These results elucidate important physical factors involved in collective cell organization and provide important references for potential applications of biomaterials in new therapies and tissue engineering. [ABSTRACT FROM AUTHOR]

The use of spherical robots in outdoor operations has increased because they can move on uneven/three-dimensional (3D) terrain. Since the non-holonomic constraints and the rolling, tilting and turning kinematics of spherical robots are coupled on 3D terrain, these operations may require complex design or advanced control techniques for stable rolling kinematics on a straight trajectory. Instead, a simple design or solution can be used for these operations. This study proposes a simple design for stable rolling kinematics of spherical robots on a straight path without changing the existing design and without a controller. The proposed design is based on coupling the spherical robots with a mechanical component and can be easily applied to all spherical robots. The proposed design does not require any change in the structure of a spherical robot, but only an additional identical spherical robot and a mechanical coupler. The main contribution and significance of this study is a simple design to overcome the stability problems of a single spherical robot operating on flat and 3D terrain. The rolling stability of the single and the coupled spherical robots on flat road and 3D terrain was investigated by kinematic analysis to verify the validity of the proposed design. The effect of the stiffness of the mechanical coupling on the rolling kinematics of the spherical robots was studied in the kinematic analysis using different mechanical couplings, such as a rigid shaft, a relatively soft spring and a relatively stiff spring. Experimental studies were conducted to verify the validity of the proposed design for the spherical robots rolling especially on 3D terrains. The results show that the proposed design, which requires only a mechanical coupler instead of a complex design or advanced controller, is reliable and feasible. The rigid mechanical coupling of the two identical spherical robots could overcome the problems of maneuvering and rolling stability of spherical robots on 3D terrains. [ABSTRACT FROM AUTHOR]

Advances in the field of processing and characterization of material behaviors are driving innovations in materials design at a nanoscale. Thus, it is demanding to develop physics-based computational methods that can advance the understanding of material Multiphysics behaviors from a bottom-up manner at a higher level of precision. Traditional computational modeling techniques such as finite element analysis (FE) and molecular dynamics (MD) fail to fully explain experimental observations at the nanoscale because of the inherent nature of each method. Concurrently coupled atomic to the continuum (AtC) multi-scale material models have the potential to meet the needs of nano-scale engineering. With the goal of representing atomistic details without explicitly treating every atom, the AtC coupling provides a framework to ensure that full atomistic detail is retained in regions of the problem while continuum assumptions reduce the computational demand. This review is intended to provide an on-demand review of the AtC methods for simulating thermo-mechanical behavior. Emphasis is given to the fundamental concepts necessary to understand several coupling methods that have been developed. Three methods that couple mechanical behavior, three methods that couple thermal behavior, and three methods that couple thermo-mechanical behavior is reviewed to provide an evolutionary perspective of the thermo-mechanical coupling methods.

Similar to Poisson's effect, mechanical coupling is a directional indirect response by a directional input loading. With the advance in manufacturing techniques of 3D complex geometry, architected materials with unit cells of finite volume rather than a point yield more degrees-of-freedom and foster exotic mechanical couplings such as axial-shear, axial-rotation, axial-bending, and axial-twisting. However, most structural materials have been built by the ad hoc design of mechanical couplings without theoretical support of elasticity, which does not provide general guidelines for mechanical couplings. Moreover, no comprehensive study of all the mechanical couplings of 3D lattices with symmetry operations has been undertaken. Therefore, we construct the decoupled micropolar elasticity tensor of 3D lattices to identify individual mechanical couplings correlated with the point groups. The decoupled micropolar elasticity tensors, classified with 32 point groups, provide 15 mechanical couplings for 3D lattices. Our findings help provide solid theoretical guidelines for the mechanical couplings of 3D structural materials with potential applications in various areas, including active metamaterials, sensors, actuators, elastic waveguides, and acoustics. [ABSTRACT FROM AUTHOR]

This paper reports an electromagnetic indirect-driving scanning mirror with an enlarged mirror plate (17 mm × 17 mm) supported by high-strength polymer hinges for wide-field coaxial LiDAR (Light Detection and Ranging) applications. An indirect-driving mechanism was developed to achieve large tilting angle through mechanical amplification, while maintaining a relatively high resonance frequency of the enlarged mirror plate. A prototype mirror was designed, fabricated, and tested. A Hall scan position sensor was integrated to monitor the pose of the mirror in real time. The testing results show a coupled resonance frequency of 54.9 Hz with an optical tilting angle of ± 60 ° , corresponding to a field of view (FoV) of 12 0 °. A wide-field coaxial LiDAR system was also built based on the indirect-driving scanning mirror, and 2D imaging was demonstrated. [Display omitted] • An indirect-driving mechanism was developed to achieve a large tilting angle and a relatively high resonance frequency. • High magnification of the tilting angle of the mirror plate was achieved through mechanical coupling. • A Hall scan position sensor was integrated to monitor the actual position of the mirror plate in real time. • A coaxial LiDAR imaging system based on the indirect-driving scanning mirror was demonstrated. [ABSTRACT FROM AUTHOR]

Dual parallel motion systems are mechanisms that drive load jointly by dual parallel motion axes. For these special mechanisms, diminishing desynchronization between parallel axes is essential to harness the potential performance of the whole system. However, a wide variety of synchronization applications tend to have great differences in control objectives and mechanical structures, which makes it laborious and time-consuming to design customized control schemes. Meanwhile, existing generalized synchronous control schemes are simply based on state compensation, which finitely offset mechanical coupling effect and limit the synchronization performance. To overcome these drawbacks, a generalized model of dual parallel motion systems is presented in this article, which can categorize the synchronous control objective into one uniform expression. By applying motion decoupling strategy to the generalized model, an advanced composite synchronous control scheme is proposed, which provides a generalized synchronization solution with comprehensively considering the motion coupling effect. Finally, simulation and experimental results on a dual-driven gantry platform verify that the proposed control scheme can significantly improve the synchronization performance. [ABSTRACT FROM AUTHOR]

Advances in the field of processing and characterization of material behaviors are driving innovations in materials design at a nanoscale. Thus, it is demanding to develop physics-based computational methods that can advance the understanding of material Multiphysics behaviors from a bottom-up manner at a higher level of precision. Traditional computational modeling techniques such as finite element analysis (FE) and molecular dynamics (MD) fail to fully explain experimental observations at the nanoscale because of the inherent nature of each method. Concurrently coupled atomic to the continuum (AtC) multi-scale material models have the potential to meet the needs of nano-scale engineering. With the goal of representing atomistic details without explicitly treating every atom, the AtC coupling provides a framework to ensure that full atomistic detail is retained in regions of the problem while continuum assumptions reduce the computational demand. This review is intended to provide an on-demand review of the AtC methods for simulating thermo-mechanical behavior. Emphasis is given to the fundamental concepts necessary to understand several coupling methods that have been developed. Three methods that couple mechanical behavior, three methods that couple thermal behavior, and three methods that couple thermo-mechanical behavior is reviewed to provide an evolutionary perspective of the thermo-mechanical coupling methods. [ABSTRACT FROM AUTHOR]

The microenergy harvesting based on magneto‐mechano‐electric (MME) coupling is an emerging technology for powering wireless Internet of Things (IoT) devices because it is capable of simultaneously harvesting magnetic field energy and mechanical energy. However, further improvement in output power of conventional cantilever‐structured MME energy harvesters has met with considerable difficulties due to the inherent, high mechanical energy loss in single‐mode operation. To solve the predicament, here, this work presents a symmetric, mechanical coupled dual‐mode MME energy harvester for restricting clamp loss and then enhancing MME coupling and output power. Under a weak AC magnetic field (Hac = 4 Oe) at 60 Hz, the MME energy harvester operating in symmetric dual‐mode can generate a peak‐peak output power of 72 mWpp (root‐mean‐square value: 9 mWRMS), a 437% enhancement over a conventional single‐mode MME energy harvester, which can even drive 160 light emitting diodes (LEDs) lighting directly. A realistic application furtherly shows that the symmetric dual‐mode MME energy harvester can successfully scavenge the magnetic field energy around a household appliance, and the generated electric power can directly drive a wireless IoT system in real time. The proposed concept of symmetric dual‐mode in this work can open new avenues for future vibration‐based energy harvesters design. [ABSTRACT FROM AUTHOR]

The direct-drive servo system of H-type platform is easily affected by load disturbance and mechanical coupling. In this paper, a discrete-time integral sliding mode position control method based on smooth saturation function is proposed. First, the discrete-time mathematical model of direct-drive servo system with mechanical coupling characteristics is established with the position and speed of mover as state variables. Then, a discrete-time integral sliding mode position controller is designed to reduce the influence of external disturbance, and improve the tracking accuracy of the system. At the same time, in order to weaken the chattering caused by the sign function in the control law, a smooth saturation function is designed to replace the original sign function, and the advantages of the smooth saturation function are analyzed and proved. Finally, the simulation and experimental results show that the proposed method not only improves the position tracking accuracy of the system, weakens the chattering, but also enhances the robustness of the system to load disturbance. [ABSTRACT FROM AUTHOR]

This paper presents AlScN piezoelectric two-axis MEMS mirrors with gimbal-less and gimbaled designs fabricated in a CMOS-compatible manner. Integrated piezoelectric sensors provided feedback signals of the actual mirror positions. The mirror with a diameter of 1.5 mm possessed adjustable optical tilt angles of up to 22.6° @ 30 V, with a high resonance frequency of about 8.2 kHz, while the 3 mm mirror reached 48.5° @ 41 V. The mirror with the gimbaled structure exhibited an excellent field of view and good mechanical decoupling. Additionally, a significant improvement in mirror scanning performance was observed in a vacuum (4 Pa), proving that the optical field of view was magnified by more than a factor of 10. [ABSTRACT FROM AUTHOR]

The paper presents a new solution for motion transmission between two shafts with non-intersecting axes. The structural considerations fundament the existence in the structure of the mechanism of three revolute pairs and a bipod contact. Compared to classical solutions, where linkages with cylindrical pairs are used, our solution proposes a kinematical chain also containing higher pairs. Due to the presence of a higher pair, the transmission is much simpler, the number of elements decreases, and as a consequence, the kinematical study is straightforward. Regardless, the classical analysis of linkages cannot be applied because of the presence of the higher pair. For the proposed spatial coupling, the transmission ratio is expressed as a function of constructive parameters. The positional analysis of the mechanism cannot be performed using the Hartenberg–Denavit method due to the presence of a bipod contact, and instead, the geometrical conditions of existence for the bipod contact are applied. The Hartenberg–Denavit method requires the replacement of the bipodic coupling with a kinematic linkage with cylindrical (revolute and prismatic) pairs, resulting in complicated analytical calculus. To avoid this aspect, the geometrical conditions required by the bipod coupling were expressed in vector form, and thus, the calculus is significantly reduced. The kinematical solution for the proposed transmission can be obtained in two ways: first, by considering the equivalent transmission containing only cylindrical pairs and applying the classical analysis methods; second, by directly expressing the condition of definition for the higher pairs (bipodic pair) in vector form. The last method arrives at a simpler solution for which analytical relations for the positional parameters are obtained, with one exception where numerical calculus is needed (but the precision of this parameter is controlled). The analytical kinematics results show two possibilities of building the actual mechanism with the same constructive parameters. The rotation motions from the revolute pairs, internal and driven, and the motions from the bipod joint were obtained through numerical methods since the equations are very intricate and cannot be solved analytically. The excellent agreement validates the theoretical solutions obtained and the possibility of applying such mechanisms in technical applications. The constructive solution exemplified here is simple and robust. [ABSTRACT FROM AUTHOR]

Detection of sound and substrate vibration is crucial for the survival and reproduction of many animals, particularly insects. Bushcrickets (Orthoptera, Tettigoniidae), developed a large mechanosensory organ complex in their legs to detect such stimuli. As demonstrated by various studies in the past, sensilla in distinct functional groups form specialized vibratory organs (the subgenual organ and the accessory organ), respond sensitively to both vibration and sound (in the intermediate organ [IO]), or mediate hearing (in the crista acustica [CA]; the tympanal hearing organ). In their recent publication, Zhantiev and Korsunovskaya addressed auditory and vibratory sensitivity in the IO and the CA in two species of bushcrickets, using single‐cell recording and staining of sensory neurons from their soma in an isolated foreleg. Their main finding was that not only the IO but also the complete CA contains bimodal sensilla responding with high sensitivity to both sound and vibration, which would be a true change in the paradigm of how the auditory/vibratory sense in Orthoptera works. In addition, they revealed vibratory tuning of the IO sensilla, which differs largely from that in previous studies. We propose three major experimental causes of such discrepancies: calibration, experiments with isolated legs, and differences in the sites of recording. To judge the causes of these discrepancies more adequately, a detailed comparison of methods and a number of control experiments are needed. This will deepen our understanding of sensory adaptations and specialization of insect mechanosensory organs to stimuli entering the system by different input pathways. Highlights: A recent publication reports high sensitivity to both sound and vibration in a specialized hearing organ of bushcrickets, which was not found in other studies.We discuss vibratory stimulation as a potential cause for divergent results. [ABSTRACT FROM AUTHOR]

In this work, we experimentally investigate the dynamics of pairs of opto-thermally driven, mechanically coupled, doubly clamped, silicon micromechanical oscillators, and numerically investigate the dynamics of the corresponding lumped-parameter model. Coupled limit cycle oscillators exhibit striking nonlinear dynamics and bifurcations in response to variations in system parameters. We show that the input laser power influences the frequency detuning between two non-identical oscillators. As the laser power is varied, different regimes of oscillations such as the synchronized state, the drift state, and the quasi-periodic state are mapped at minimal and high coupling strengths. For non-identical oscillators, coexistence of two states, the synchronized state and the quasi-periodic state, is demonstrated at high coupling and high laser power. Experimentally, this bistability manifests as irregular oscillations as the system rapidly switches between the two states due to the system’s sensitive dependence on initial conditions in the presence of noise. We provide a qualitative comparison of the experimental and numerical results to elucidate the behavior of the system. [2022-0005] [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Power is generated in a variety of ways, including renewable energy, nuclear power, and burning of fossil fuels. The majority of our power is currently generated by burning fossil fuels, mostly natural gas and coal, to spin turbines attached to an electromagnetic generator. The main advantage of AC generation is that the voltage levels can be altered up and down with transformers, allowing electricity to be sent across long distances to the loads that demand it. The excitation system demand for large synchronous generators with a few hundred-megawatt ratings becomes very enormous. The challenge of transmitting such a big amount of power through high-speed sliding contacts becomes daunting. Mechanical coupling with exciter for synchronous generators is essential to mitigate such problems as the corrected output is linked directly to the field winding. This paper aims to develop a simulation of a 3-phase diesel engine-based 2 MVA/400 V synchronous generator with mechanical coupling and an exciter system. The developed simulation of the synchronous machine is set to deliver 25 % of its rating value (500 kW) till the time of 3 sec. Then, additional power of 1 MW is switched at t=3 sec via a 3-phase circuit breaker. The dynamic response of field current and field voltage of the simulation shows reasonable step performance as the steady-state time is less than 3 sec. The control of the excitation system allows the generator to maintain voltage, control reactive power flow, and assist in maintaining power system stability. The simulation was accurate when measuring the voltage and current under these changes. This analysis can help to investigate further integration with renewable energy sources [ABSTRACT FROM AUTHOR]

Under high temperature and stress reservoir conditions, proppant embedment induced by the time-dependent creep behavior of shale rocks has posed great challenges to the long-term maintenance of fracture conductivity in unconventional reservoirs. In this study, a numerical workflow combining a 3D continuum–discrete mechanical coupling approach with the lattice Boltzmann (LB) method is developed to simulate the coupled thermal–mechanical process in a rock/proppant system and to investigate the role of the time-dependent deformation of shale rocks on proppant embedment and fracture conductivity loss under varying temperature and stress conditions. The numerical workflow is first compared with an experiment under varying temperature and stress conditions to calibrate the elastic, plastic, viscoelastic, and thermal properties of the shale rock, as well as the proppant properties. Then, the effect of fracture axial and confining stress, numbers of proppant layers, proppant size, proppant spatial distribution, and proppant crushing is systematically investigated. The simulation results indicate that when the rock creep is significant, large size and a multilayer of proppant structure are suggested to maintain the fracture conductivity. The small percentage of particle breakage in a proppant assembly plays a less important role in the long-term maintenance of fracture conductivity. The findings of this study will shed light on the creep-induced proppant embedment mechanisms at reservoir conditions as well as their influence on the sustainability of fracture conductivity over long periods of time. [ABSTRACT FROM AUTHOR]

This paper presents AlScN piezoelectric two-axis MEMS mirrors with gimbal-less and gimbaled designs fabricated in a CMOS-compatible manner. Integrated piezoelectric sensors provided feedback signals of the actual mirror positions. The mirror with a diameter of 1.5 mm possessed adjustable optical tilt angles of up to 22.6° @ 30 V, with a high resonance frequency of about 8.2 kHz, while the 3 mm mirror reached 48.5° @ 41 V. The mirror with the gimbaled structure exhibited an excellent field of view and good mechanical decoupling. Additionally, a significant improvement in mirror scanning performance was observed in a vacuum (4 Pa), proving that the optical field of view was magnified by more than a factor of 10.

In this work, we develop a general model of a mass sensor made of N weakly mechanically coupled microbeams subject to electric actuation. The developed model is verified by comparing the simulated pull-in voltages, natural frequencies, and frequency response of a two-weakly coupled beam system against their experimental counterparts reported in the literature. The sensitivity of the mass sensor in terms of frequency shift is observed to significantly increase when enlarging the size of the beams array. The simulation results reveal a clear transformation of the frequency response from a nearly linear to nonlinear behavior as result of the deposition of a small mass on the coupled system. As such, we show the potential use of bifurcations that result in an abrupt jump to a large-amplitude motion for sensing purposes. Furthermore, by exploiting the mode localization effect, the nonlinear response can be triggered on one of the beams when an added masses is introduced, allowing for an amplitude-based mass detection mechanism of the device. The proposed sensing method has the possibility to operate in bifurcation mode for mass threshold detection that can be tuned using the AC actuation or in continuous mode based on extracting the added mass from the amplitude of the sensing beam's oscillations. [ABSTRACT FROM AUTHOR]

Aluminium-based composite processed with spark plasma sintering was modelled with COMSOL Multiphysics. This was aimed at investigating the effect of the SPS process parameters on thermal and mechanical stresses induced in the sintered Al-CNTs-Nb composite samples. The modelling employed optimal parameters used in the laboratory to fabricate the samples. The physics included electro-thermo-mechanical coupling. The geometry was 2D axisymmetric while the parameters were based on temperature-dependent properties. Only the consolidated sample was modelled and simulated to simplify the modelling. Results obtained showed that the simultaneous heating and application of pressure enhanced the sintering efficiency and the properties of the product. The least von Mises stress as well as least thermal stress were obtained at a pressure of 30 MPa as against 20 MPa and 10 MPa. This implied that higher pressure produced lower stresses. Therefore, it can be concluded that high sintering pressure reduces mechanical and thermal stresses and improves the properties of the composite. [ABSTRACT FROM AUTHOR]

Mechanical coupling between the drive and the driven systems in electrical machines poses design challenges. Rigid and flexible couplings have a trade-off between the rotational speed and vibrations, which are associated with misalignment. This paper discusses a procedure for obtaining the dimensions of a pre-designed rigid (flange-type) mechanical coupling system using the finite element-based electromagnetic full-wave simulator element software (FE, ANSYS) for a benchmark torque and proposes a process that replaces a mechanical coupling system by a magnetic coupling system. This paper also elaborates on the comparative performance analysis between magnetic coupling and mechanical coupling. The simulation results of this analysis affirm that adjusting the flange diameter and thickness tune the magnetic coupling system performance similar to that of the mechanical coupling with an added advantage of auto-decoupling when exposed to higher loads. The auto-decoupling property protects the mechanical and electrical system from damage. This research considers the use of COMSOL Multiphysics software for determining the optimum number of magnets to couple the flanges for specified torque and speed, the distance between the flanges, and limits of angular and parallel misalignments. JMAG software is used for the analysis of the dynamic behaviour of the magnetic coupling system and the holding torque characteristics. This manuscript shows that the magnetic coupling technique has promising results in the renewable energy industry, such as wind energy, wave energy and electric vehicles. [ABSTRACT FROM AUTHOR]

Ｔｅｍｐｅｒａｔｕｒｅ Ｆｉｅｌｄ ａｎｄ Ｓｔｒｅｓｓ Ｆｉｅｌｄ Ｓｉｍｕｌａｔｉｏｎ ｏｆ Ｔｉｔａｎｉｕｍ Ａｌｌｏｙ Ｌａｓｅｒ Ｆｕｓｅ Ａｄｄｉｔｉｖｅ Ｍａｎｕｆａｃｔｕｒｉｎｇ [ABSTRACT FROM AUTHOR]

The resonant frequency difference of piezoelectric transformers (PTs) with a classical parallel connection could worsen system performance, then the mechanical coupling of PTs was proposed to avoid the disadvantage. Experimental results showed that when the difference was relatively small, the performance of the classical parallel system and proposed mechanical coupling system was similar. However, when the difference increased, the maximum output power of a classical parallel system at a temperature rise of 20 °C reduced by 32.6% and that of mechanical coupling system reduced by 7.7%. This indicated mechanical coupling was better than classical parallel connection in improving the output power of PTs. [ABSTRACT FROM AUTHOR]

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• A mode-localized mass sensor composed of two different cantilevers is presented. • The initial asymmetric system is balanced with the electrostatic force. • The design allows to overcome manufacturing imperfections. • The mechanical coupling is taken into account in the proposed model. • The designed device is fabricated and the proposed model is experimentally validated. This paper presents a sensor using the mode localization phenomenon to detect a mass perturbation. It is composed of two cantilevers with different lengths and connected by a coupling beam. The short cantilever is electrostatically actuated and by changing the applied DC voltage, we can reduce its stiffness and reach the veering point, which corresponds to a balanced system. This principle allows us to overcome the manufacturing defect which perturbs the initial system. An analytical model using the Euler-Bernoulli beam theory is developed for the design. The equation of the continuous system is discretized with the Galerkin method and simulations are performed. The designed device composed of polysilicon coupled microbeams is then fabricated with the Multi-User MEMS Processes and an experimental investigation is carried out. Three devices with different coupling are considered with a length ratio of 0.98. This ratio is suitable to reach the veering point by using a DC balancing voltage around the half of the pull-in voltage. The comparison between theoretical and experimental results shows a good agreement for each device. [ABSTRACT FROM AUTHOR]

Vibration and acoustic noise in switched reluctance motor (SRM) drives have been investigated and addressed frequently. However, the focus of most the paper is on vibration of the stator frame due to radial electromagnetic forces acting on the stator teeth. In this paper, a comprehensive vibration analysis for a SRM assembly using finite element (FE) method is conducted, which considers the stator and rotor vibrations due to radial electromagnetic force as well as the effect of mechanical coupling on the vibration between the stator and rotor. First, an experimental modal test was performed to extract modal parameters and to observe the coupling effect. The parameters were then used to adjust and validate the FE model that was used to obtain transfer functions for vibration characterization. Using the frequency domain representation of the radial magnetic force vector and the calculated transfer functions, radial and tangential vibration components have been predicted. [ABSTRACT FROM AUTHOR]

Abstract The widely used Pseudo-Two-Dimensional (P2D) cell model for Li-ion batteries is generally based on a simplified lithium diffusion model of active particles with certain geometry. In this work, we propose a two-level framework, which extends the P2D cell model and incorporates a mechanically coupled phase-field Cahn–Hilliard diffusion model of active particles. The phase-field model allows more detailed diffusion study in particles of general geometry and includes the full coupling of the mechanics and phase separation. To improve the computational efficiency, we manage to reduce one degree of freedom at the cell level by treating the ion flux between the electrolyte and active particle as a dependent quantity. The two-level framework is validated against the original one and applied to study the impact of particle geometry, finite deformation elasticity and phase separation on the cell performance. Results show that the oblate particle has better cell performance than other spheroidal particles. It is attributed to the mechanical drifting at the higher curvature. Highlights • Two-level framework incorporate multiphysical particle level modeling to cell mode. • The existence of stresses can enhance the bulk diffusion improve the cell performance. • The ellipsoidal particles have better cell performance than spherical particles. • Diffusion dynamic has a larger impact on the cell performance than particle shapes. • Capacity can be improved as the stiffness of the particle increase. [ABSTRACT FROM AUTHOR]

Abstract The present work investigates the effect of different outermost connector types on the hydrodynamic responses of a modular multi-purpose floating structure (MMFS) system. The MMFS system is preliminarily designed for a mild sea zone, which is composed of a number of standardized floating modules. In this study, the MMFS system has been simplified as a seven-module connected system. Considering the structural deformation of the MMFS system mainly occurs in the connectors among adjacent modules, each module is viewed as a rigid body. Both the hydrodynamic interaction effect and mechanical coupling effect among modules have been taken into consideration in the time-domain analysis. Different outermost connector designs have been proposed and investigated for the MMFS system. The results indicate that the hydrodynamic responses of the MMFS system are sensitive to the effects of the connector types, the wave phase, and the wavelength. The hinge-type design of the outermost connector can significantly reduce the extreme responses of both the bending moment and the shear force of the connectors. The additional PTO damper design for the outermost hinge-type connector can effectively reduce the motion of the outermost module, and also produce considerable wave energy. Highlights • Different outermost connector types can strongly influence the hydrodynamic responses of the MMFS system. • A proper PTO system for the outermost hinge connector, can effectively produce considerable wave energy. • The length-ratio effect on the hydrodynamic responses of the MMFS system has been figured out. • Proper outermost connector design can significantly reduce the extreme responses of the MMFS system. [ABSTRACT FROM AUTHOR]

Microelectromechanical System (MEMS)-based scanning mirrors are important optical devices that have been employed in many fields as a low-cost and miniaturized solution. In recent years, the rapid development of Light Detection and Ranging (LiDAR) has led to opportunities and challenges for MEMS scanners. In this work, we propose a 2D electrostatically actuated micro raster scanner with relatively large aperture. The 2D scanner combines a resonant scanning axis driven by an in-plane comb and a quasistatic scanning axis driven by a vertical comb, which is achieved by raising the moving comb finger above the fixed comb finger through the residual stress gradient. The analytic formula for the resonant axis frequency, based on the mechanical coupling of two oscillation modes, is derived and compared with finite element simulation. A prototype is designed, fabricated, and tested, and an overall optical Field-of-View (FoV) of about 60° × 4° is achieved. Finally, some possibilities for further improvement or optimization are discussed.

Abstract Short- and long-term processes at or close to the subduction plate interface (e.g.,mineral transformations, fluid release, seismicity and more generally deformation) might be more closely related than previously thought. Increasing evidence from the fossil rock record suggests that some episodes of their long geological evolution match or are close to timescales of the seismic cycle. This contribution uses rocks recovered (episodically) from subduction zones, together with insights from thermomechanical modelling, to provide a new dynamic vision of the nature, structure and properties of the plate interface and to bridge the gap between the mechanical behavior of active subduction zones (e.g.,coupling inferred from geophysical monitoring) and fossil ones (e.g.,coupling required to detach and recover subducted slab fragments). Based on critical observations and an exhaustive compilation of worldwide subducted oceanic units (for which the presence near the plate interface, rock types, pressure, temperature, T/P gradients, thickness and timing of detachment can be assessed), the present study demonstrates how long-term mechanical coupling exerts a key control on detachment from the slab and potential rock recovery. Critical assessment of rock T/P characteristics indicates that these fragments can indeed be used as natural probes and provide reliable information on subduction interface dynamics down to ~2.8 GPa. Rock clusters are identified at depths of 30, 55–60 and 80 km, with some differences between rock types. Data also reveal a first-order evolution with subduction cooling (in the first ~5 Myr), which is interpreted as reflecting a systematic trend from strong to weak mechanical coupling, after which subduction is lubricated and mostly inhibits rock recovery. This contribution places bounds on the plate interface constitution, regular thickness (<300 m; i.e. where/when there is no detachment), changing geometry and effective viscosity. The concept of 'coupled thickness' is used here to capture subduction interface dynamics, notably during episodes of strong mechanical coupling, and to link long- and short-term deformation. Mechanical coupling depends on mantle wedge rheology, viscosity contrasts and initial structures (e.g.,heterogeneous lithosphere, existence of décollement horizons, extent of hydration, asperities) but also on boundary conditions (convergence rates, kinematics), and therefore differs for warm and cold subduction settings. Although most present-day subduction zone segments (both along strike and downdip) are likely below the detachment threshold, we propose that the most favorable location for detachment corresponds to the spatial transition between coupled and decoupled areas. Effective strain localization involves dissolution-precipitation and dislocation creep but also possibly brittle fractures and earthquakes, even at intermediate depths. Highlights • Subduction plate interface constitution, thickness, geometry and viscosity • Rocks recovered are reliable probes of subduction processes and thermal regimes • Long-term mechanical coupling controls rock recovery from subduction zones • Subduction cooling induces a long-term trend in rock detachment from the slab • Rock recovery is a proxy for long- and short-term subduction dynamics and coupling [ABSTRACT FROM AUTHOR]

Dual-linear-motor-driven gantry systems have been widely used in high-speed or heavy payload precision motion systems. Due to the unique physical properties such as mechanical coupling, the precise synchronization control of such kinds of systems is crucial to achieve good tracking and smooth operation performance. However, the existing synchronization schemes usually focus on the pure motion synchronization only and, thus, have certain inherent performance limitations. In this paper, an accurate multi-input multi-output mathematical model of a dual-driven gantry is presented first, where the complete planar motions of the crossbeam include the traditional linear motion along the guide rails and the previously ignored rotational motion around the mass center. With the better understanding of the mechanical coupling and the internal forces caused by the rotational dynamics, an advanced synchronization control scheme by directly taking into account the additive rotational dynamics is presented, which not only synchronizes the motions of two parallel motors but also regulates the internal forces. In the proposed scheme, the adaptive robust control algorithm is also applied to obtain a guaranteed robust performance in the presence of both parametric uncertainties and uncertain nonlinearities. Comparative experiments with previous control schemes are carried out to show the better synchronization performance and verify the effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

The authors present an experimentation demonstration and a numerical simulation using structural finite element analysis of assembled honeycomb plates used for satellites design. A detailed comprehension of the dynamics of the coupled structures is essential for the design and the development of new structures and to give the solution to problems of noise and vibration on existing structures. This comprehension passes by the study of the modal analysis, which makes it possible to describe, include/understand and model the behavior of the coupled structures. The knowledge of the vibration behavior of the coupled structures being able to take into account its environment is a difficult problem and the engineer often has recourse to artefacts to give an estimate of it. A modal analysis of a coupled system composed of two and three sandwich plates with aluminum skins and hexagonal honeycomb core in free vibrations is presented in this study under the Clumped-Free-Free-Free boundary conditions. In this paper, the comparative study has been performed using the experimental data. The results obtained in this paper show that a good agreement is observed between the finite elements results and the experimental methods by accepting an error about less than 6%. [ABSTRACT FROM AUTHOR]

• A tripod joint-CV joint transmission between parallel axis shafts can be homokinetic. • If connected to a CV joint, a tripod joint performs better than previously expected. • On cars, tripod joints can still be a good alternative to CV joints. • The transmission ratio of a tripod joint-CVJ driveshaft can now be exactly assessed. The paper presents a procedure to assess the instantaneous transmission ratio, in a generic configuration, of a driveshaft equipped with a tripod joint and a constant velocity joint of the fixed type. This mechanical transmission is used, for example, in automobiles to connect each half shaft of the differential to a driving wheel. After highlighting that the usual approach to evaluating the instantaneous transmission ratio is conceptually flawed, the paper proposes an original procedure to correctly assess the transmission ratio. The paper also proves that the considered driveshaft is homokinetic whenever the axes of the two end shafts are parallel. Numerical examples show application of the proposed procedure to case studies. [ABSTRACT FROM AUTHOR]

The bandwidth characteristics of a tuning fork micro-gyroscope with mechanically coupled sense mode were investigated in this paper to provide some references for mechanical bandwidth design. The concept of sense mode mechanical coupling is introduced first. Theoretical frequency response analyses were then carried out on the mechanical part of the gyroscope. Equations representing the relationships between the differential output signal and the frequency of the input angular rate were deduced in full frequency range and further simplified in low frequency range. Based on these equations, bandwidth characteristics under ideal and non-ideal conditions are discussed. Analytical results show that under ideal conditions, the bandwidth characteristics of a tuning fork micro-gyroscope are similar to those of a single mass micro-gyroscope, but under non-ideal conditions, especially when sense mass and/or stiffness are asymmetric, the bandwidth characteristics would be quite different because the in-phase mode would participate in the anti-phase vibration response. Experimental verifications were carried out on two micro-gyroscope prototypes designed in our laboratory. The deduced equations and analytical results can be used in guiding the mechanical bandwidth design of tuning fork micro-gyroscopes with mechanically coupled sense mode.

The tectonic structure of the Guadalquivir foreland basin becomes complex eastward evolving from a single depocenter to a compartmented basin. The deformation pattern within the eastern Guadalquivir foreland basin has been characterized by combining seismic reflection profiles, boreholes, and structural field data to output a 3-D model. High-dipping NNE-SSW to NE-SW trending normal and reverse fault arrays deform the Variscan basement of the basin. These faults generally affect Tortonian sediments, which show syntectonic features sealed by the latest Miocene units. Curved and S-shaped fault traces are abundant and caused by the linkage of nearby fault segments during lateral fault propagation. Preexisting faults were reactivated either as normal or reverse faults depending on their position within the foreland. At Tortonian time, reverse faults deformed the basin forebulge, while normal faults predominated within the backbulge. Along-strike variation of the Betic foreland basin geometry is supported by an increasing mechanical coupling of the two plates (Alborán Domain and Variscan basement) toward the eastern part of the cordillera. Thus, subduction would have progressed in the western Betics, while it would have failed in the eastern one. There, the initially subducted Iberian paleomargin (Nevado-Filábride Complex) was incorporated into the upper plate promoting the transmission of collision-related compressional stresses into the foreland since the middle Miocene. Nowadays, compression is still active and produces low-magnitude earthquakes likely linked to NNE-SSW to NE-SW preexiting faults reactivated with reverse oblique-slip kinematics. Seismicity is mostly concentrated around fault tips that are frequently curved in overstepping zones. [ABSTRACT FROM AUTHOR]