Mechanics Of Motion Research Articles

Lateral Motion of Towed Underwater Vehicle within the Problem of Continental Shelf Monitoring

Lateral motion dynamics was studied of a robotic towed underwater system designed to monitor the continental shelf and consisting of a towed vehicle and a tow wireline. In regard to underwater vehicles of the type in question, it is quite correct to represent spatial motion in the form of a super-position consisting of two flat motions, i.e., longitudinal motion in the vertical plane and lateral motion in the horizontal plane. Dynamics of the towed system longitudinal motion within the monitoring problem was considered in a previously published work by the authors. The present work is its natural continuation and development traditionally accepted in the problems of the underwater vehicles spatial motion mechanics. Diagram of the towed vehicle operation and its hydrodynamic characteristics are presented; besides, mathematical model of a wireline and also a model of the wireline-towed vehicle system lateral motion were constructed. Probable steady system motions were analyzed, issues of balancing, as well as those of the towed vehicle dynamic stability when moving at a constant depth were considered. Results of numerical calculations were provided. The results obtained were considered in conjunction with the results of the authors' above mentioned work related to the towed vehicle longitudinal motion and make it possible to select such system parameters that provide the specified character of spatial movements in the process of monitoring the continental shelf taking into consideration the need to perform turns in the horizontal plane at changing directions and to ensure vertical maneuvers when avoiding underwater obstacles.

Optimal Learning and Self-Awareness Versus PDI

This manuscript will explore and analyze the effects of different paradigms for the control of rigid body motion mechanics. The experimental setup will include deterministic artificial intelligence composed of optimal self-awareness statements together with a novel, optimal learning algorithm, and these will be re-parameterized as ideal nonlinear feedforward and feedback evaluated within a Simulink simulation. Comparison is made to a custom proportional, derivative, integral controller (modified versions of classical proportional-integral-derivative control) implemented as a feedback control with a specific term to account for the nonlinear coupled motion. Consistent proportional, derivative, and integral gains were used throughout the duration of the experiments. The simulation results will show that akin feedforward control, deterministic self-awareness statements lack an error correction mechanism, relying on learning (which stands in place of feedback control), and the proposed combination of optimal self-awareness statements and a newly demonstrated analytically optimal learning yielded the highest accuracy with the lowest execution time. This highlights the potential effectiveness of a learning control system.

Symplectic coarse-grained dynamics: Chalkboard motion in classical and quantum mechanics

In the usual approaches to mechanics (classical or quantum) the primary object of interest is the Hamiltonian, from which one tries to deduce the solutions of the equations of motion (Hamilton or Schrodinger). In the present work we reverse this paradigm and view the motions themselves as being the primary objects. This is made possible by studying arbitrary phase space motions, not of points, but of (small) ellipsoids with the requirement that the symplectic capacity of these ellipsoids is preserved. This allows us to guide and control these motions as we like. In the classical case these ellipsoids correspond to a symplectic coarse graining of phase space, and in the case they correspond to the quantum blobs we defined in previous work, and which can be viewed as minimum uncertainty phase space cells which are in a one-to-one correspondence with Gaussian pure states.

On the Aizerman Problem: Coefficient Conditions for the Existence of a Four-Period Cycle in a Second-Order Discrete-Time System

We consider in this paper an automatic control second-order discrete-time system whose nonlinearity satisfies the generalized Routh–Hurwitz conditions. Systems of this type are widely used in solving modern application problems that arise in engineering, theory of motion control, mechanics, physics, and robotics. Two constructed examples of discrete-time systems with nonlinearities that lie in a Hurwitz angle were presented in recent papers by W. Heath, J. Carrasco, and M. de la Sen. These examples demonstrate that in the discrete case, the Aizerman and Kalman conjectures are untrue even for second-order systems. One such system in these examples has a three-period cycle and the other system, a four-period cycle. We assume in the present paper that the nonlinearity is two-periodic and lies in a Hurwitz angle; here, we study a system for all possible parameter values. We explicitly present the conditions (for the parameters) under which it is possible to construct a two-periodic nonlinearity in such a way that a system with it is not globally asymptotically stable. Such a nonlinearity can be constructed in more than one way. We propose a method for constructing the nonlinearity in such a way that a family of four-period cycles is found in the system. The cycles are nonisolated; any solution of the system with the initial data, which lies on a certain specified ray, is a periodic solution.

КВАНТОВАЯ КАРЬЕРНАЯ ПОДЪЕМНО-ТРАНСПОРТНАЯ МАШИНА

Introduction: Mastering of the methods of energy extraction from the physical vacuum and their implementation in engineering will change the motion mechanics and the pattern of using lift-and-transport machinery if those are equipped with quantum engines (QEs). Purpose of the study: The study is aimed to develop a conceptual foundation and a working hypothesis for the operation of quantum quarrying lift-and-transport machinery (QQLTM). Problem statement: The paper addresses challenges of rock transportation from the pit bottom to the upper levels. Methods: The thrust vector is decomposed into orthogonal components. A QQLTM force balance and motion equation is derived. Typical modes of QQLTM operation are determined. Calculations as well as graphical-and-analytical studies are performed. Results: The paper presents the results of calculations regarding time and energy consumption required for rock transportation, describing the motion of loaded QQLTM during rock transportation from the pit bottom to the transfer station and the upper level of a quarry. Discussion: The existing groups of motor and railway vehicles as well as lift-and-transport machinery can be substituted by groups of transport machines with QEs — QQLTM. This will allow for the significant improvement of quarrying technology, implementation of continuous cargo transportation without transshipment, reduction of energy consumption as well as material expenditures and labor efforts.

Serpentine and Rectilinear Motion Generation in Snake Robot Using Central Pattern Generator with Gait Transition

This paper contributes to the fabrication of a snake-like robot in which the motion can be achieved through active wheels. The robot is constructed in such a way that its size can be increased and decreased, as well as it can undulate into a sine wave-like shape. The snake robot with wheels consists of chain of links attached to each other with the help of the passive prismatic and revolute joints. A neural oscillator-based central pattern generator (CPG) algorithm is applied to the robot so that rhythmic serpentine as well as rectilinear motions can be generated in it. In addition, a novel smooth transition mechanics of robot motion, from stationary position to serpentine or rectilinear motion as well as transition between these two gaits, is also suggested in the paper. The working of the formulated CPG motion algorithm is realized through experimental setup equipped with a motion capture system as well as through simulations.

Investigating the mechanisms of downslope motions of granular particles in small-scale experiments using magnetic tracking system

Laboratory experiments consisting of releasing dry rigid blocks on an inclined chute have been designed to investigate the mechanisms involved in downslope motions of granular particles. The varied parameters are the slope inclination, volume and arrangement of the initial mass. The rigid blocks are made of mortar, in which one of them is implanted with a permanent magnet inside as a tracker. The permanent magnet is wrapped by a lightweight material and then by a layer of mortar so that the densities and surface friction coefficients of all blocks used in the rock fall are similar. A non-invasive tracking technology is applied to measure the positions of the tracker by recording the static magnetic fields generated. Displacements, as well as the orientations of the tracker, are derived using appropriately developed algorithms with necessary calibrations. Runout distance is measured manually and its relationships with slope inclination, initial volume and arrangement are discussed. The results obtained highlight the influence of the initial volume on runout distance from the analysis of the distributions of tracker's velocity and acceleration. The movement of the block is divided into two phases based on the distributions of translational kinetic energy. The result shows that the movement within the depositional area is more important in terms of its contribution to the longer runout from a larger initial volume. The magnetic tracking system shows great potential in capturing dynamic behaviours of a tracker block within a moving mass. In addition to translational motions, rotational characteristics of a moving particle can be obtained. As highlighted by the experimental results, larger volume tends to inhibit the rotations while producing propulsions to block at the front-most part.

Emergent Quantum Dynamics of Vortex-Line under Linear Local Induction Approximation**Supported by the National Natural Science Foundation of China under Grant No 1167402.

Using the linear local induction approximation, we investigate the self-induced motion of a vortex-line that corresponds to the motion of a particle in quantum mechanics. Provided Kelvin waves, the effective Schrödinger equation, physical quantity operators, and the corresponding path-integral formula can be obtained. In particular, the effective Planck constant defined by parameters of vortex-line motion shows the mathematical relation between the two fields. The vortexline–particle mapping may help in understanding particle motion in quantum mechanics.

An Osteopathic Approach to Traumatically Induced Mechanical Dyspnea: A Case Report

Abstract Mechanical dyspnea (breathing pattern disorders), such as hyperventilation or hypoventilation, can result in increased pain and have negative mechanical, psychological, emotion, and biochemical effects.1,2,3 Proper breathing helps to stabilize the spine, maintain posture, and decrease anxiety. Injuries to the abdominal and pelvic diaphragms can disrupt proper breathing mechanics, leading to increased pain, anxiety, poor posture, and poor spinal and overall body mechanics. Osteopathic manipulative treatment can help restore proper diaphragmatic motion and proper breathing mechanics as the present case will demonstrate.

Brownian Motion and Quantum Mechanics

A theoretical parallel between the classical Brownian motion and quantum mechanics is explored via two stochastic sources. It is shown that, in contrast to the classical Langevin force, quantum mechanics is driven by turbulent velocity fluctuations with diffusive behavior. In the case of simultaneous action of the thermal and quantum noises, the quantum Brownian motion is described as well.

Numerical model for the fluid–structure interaction mechanics of a suspended flexible body

This study investigates the dynamic vibration and static deformation of a long flexible underwater body suspended from the ocean surface. A numerical model is constructed by considering (i) the structural mechanics, (ii) hydrodynamic forces induced by vortex shedding, (iii) motion mechanics associated with the free bottom end of the suspended body, and (iv) the interactions among (i)-(iii). Numerical computations are performed by applying uniform vertical distributions of the ocean flow speed and a sheared distribution, and by varying the weight of the body at the free bottom end. Comparing the computed results of these cases elucidates the mechanics of the fluid–structure interaction of the suspended body. In particular, the sheared flow velocity profile allows the growth of multiple frequency components of vibrations in the flexible body. The frequency multiplicity at a point in the body arises from the vortex-induced vibrations excited at that point, and those that are excited in other regions then propagate to that point.

Physical interpretation of moment tensor and the energetics of shear faulting

Moment tensor is a basic concept of source representation in seismology, established in the 1970s. On the basis of theoretical consideration to the equation of motion in continuum mechanics, we clarified the physical meaning of the Backus-Mulcahy moment tensor and derived a fundamental equation that the moment tensor of a seismic event is mathematically equivalent to the volume integral of coseismic static stress changes over the whole region. This equation provides new perspectives on the interaction between the inelastic source process and the elastic process in the surrounding region. As an example, we applied it to the energetics of shear faulting and obtained a quantitative relation between the work done for shear faulting and the static change in elastic strain energy in the surrounding region. With this energy equation, we elucidated the theoretical background of the Wallace-Bott hypothesis; that is, when the level of background tectonic stress is much higher than coseismic stress changes, the most probable orientation of slip on a given fault is parallel to the maximum resolved shear stress there in the sense of the efficiency of shear-strain energy release in the surrounding region.

The Effects of Short-Term Wearing of Customized 3D Printed Single-Sided Lateral Wedge Insoles on Lower Limbs in Healthy Males: A Randomized Controlled Trial.

BackgroundUnbalanced standing and gait asymmetry are common in individuals with musculoskeletal disorders. Achieving symmetrical posture and gait is an important goal of rehabilitation. This study investigated the biomechanical differences in the lower extremities observed immediately after an insole was used and without the use of different one-sided insoles.Material/MethodsThirty young, healthy adult males received 3 different insole interventions: experimental group A had a customized 3-dimensional (3D)-printed single-sided lateral wedge insole (CLWI) inserted on the left side, and experimental group B had on the left side, a traditional single insert. The control had unilateral flat insoles; no insole inserted into the socks. Motion mechanics and gait parameters were collected at the 2-time points, after insertion of the insole and after 20 minutes of walking with the insole.ResultsAsymmetric posture and gait appeared immediately after using the 2 insoles (lower joint moment, P<0.05). Compared with the control group, the abnormal posture and gait of experimental group B after wearing the traditional insole for 20 minutes were not obvious (P>0.05). However, the asymmetrical posture and gait remained in experimental group A after wearing the CLWI for 20 minutes (P<0.05). The center of pressure (COP) trajectory of the left foot of experimental group A was significantly higher than that of experimental group B and the control group at the 2-time points (P<0.05).ConclusionsThe asymmetry of posture and gait can be observed in a short time using a customized 3D-printed single-sided lateral wedge insole. This experiment provides guidance for the application of customized 3D-printed single-sided lateral wedge insoles for gait rehabilitation.

Modeling the mechanics of particle motion in the air purification apparatus

The paper presents the description of the new high-performance design of the inertial air flow purification system for cooling systems of radio-electronic equipment. The two-stage design of the apparatus is proposed; the first stage is centrifugal-shock and the second is inertial there. Discharge of solid particles, which are dangerous for the cooling system, is carried out in the lower part. The processes modeling was carried out based on a probabilistic approach. An expression for the differential function of number distribution of elements of polluted flow on dimensionless parameter is obtained; equations for calculating statistical averages are proposed. The obtained theoretical dependences can be applied to determine the main modes of operation of cooling systems, at which the ingress of solid particles into the air ducts of radio-electronic equipment and the destruction of its elements are prevented. The spatial 3-D pattern of the structure of gas flows in the apparatus is built using computer simulation methods; it allows to calculate the necessary parameters of the developed model and to assess the presence of stagnant zones and eddy currents, which adversely affect the performance and throughput of the device. It was proposed to increase the wall thickness of the internal elements to 2÷4 mm in order to reduce the hydraulic resistance and the speeds of air flow in the central part.

Cervical VEMP tuning changes by Meniere's disease stages.

ObjectiveTo determine if changes in cervical vestibular‐evoked myogenic potential (cVEMP) testing reflect the different stages of cochlea‐saccular hydrops in Meniere's disease (MD).MethodsThis is a case‐control retrospective series. Forty‐seven patients with unilateral MD by American Academy of Otolaryngology–Head and Neck Surgery diagnostic and staging criteria, and 30 with non‐MD vertigo as control. Meniere patients were further classified based on symptoms at the time of testing as active or stable. Subsequently, patients underwent cVEMP testing by tone‐burst stimuli at 500 and 1,000 Hz. The main outcome measure was to compare the cVEMP 1,000 and 500 Hz amplitude ratio in ears with MD and non‐MD vertigo, and in active versus stable MD.ResultsThe cVEMP 1,000/500 Hz amplitude ratio was higher in Meniere's ears (mean = 1.14 μV, SD = 0.25) than in non‐Meniere's ears (mean = 0.96 μV, SD = 0.2) (Student's t test, P = .001), and higher in active (mean = 1.22 μV, SD = 0.25) than in stable MD (mean = 1.00 μV, SD = 0.18) (P = .0035). The diagnostic value of cVEMP 1,000/500 Hz amplitude ratio to differentiate MD versus non‐MD vertigo was evaluated with a receiver‐operating characteristics (ROC) curve and the area under the curve (AUC) was 0.716 (95% confidence interval [CI] [0.591, 0.829]). The ideal cutoff point was 0.9435 with sensitivity and specificity values of 83% and 53%, respectively. The sensitivity and specificity values for this test to differentiate active versus stable MD were 68% and 81%, respectively, with AUC 0.746 (95% CI [0.607, 0.885]) and cutoff value of 1.048. In all ears, the 1,000/500 Hz amplitude ratio increased by a decrease of the 500 Hz amplitude with increasing age.ConclusionThe cVEMP 1,000/500 Hz amplitude ratio is elevated in ears with MD but not in those with non‐MD vertigo. After corrected by age, this ratio is higher in active but not in stable MD, probably reflecting dynamic changes in saccular membrane motion mechanics in hydrops, and may be a useful marker of disease progression and the effect of therapy.Level of EvidenceIV

Orbital transport system - the concept and mechanics of orbital motion

A brief introduction to the meaning of on-orbit services and research on space-based services is provided in this work. In the context of on-orbit service, the near-circular orbit is idealized as a disturbed circular orbit, and a general equation for the optimal maneuver of the near-circle orbit is presented. The examples of coplanar on-orbit services in low, medium and high orbits are analyzed respectively, and the best maneuvering scheme for orbit transfer is solved by special software. Further analysis of the impact of different heights of parking orbit on the optimal maneuvering scheme reveals that the closer parking orbit to the target orbit, the less energy is required for maneuvering, but the phase-modulation time and the transport capacity of the launch vehicle should be considered comprehensively.

Sensorless Estimation of the Planar Distal Shape of a Tip-Actuated Endoscope.

Traditional endoscopes consist of a flexible body and a steerable tip with therapeutic capability. Although prior endoscopes have relied on operator pushing for actuation, recent robotic concepts have relied on the application of a tip force for guidance. In such case, the body of the endoscope can be passive and compliant; however, the body can have significant effect on mechanics of motion and may require modeling. As the endoscope body's shape is often unknown, we have developed an estimation method to recover the approximate distal shape, local to the endoscope's tip, where the tip position and orientation are the only sensed parameters in the system. We leverage a planar dynamic model and extended Kalman filter to obtain a constant-curvature shape estimate of a magnetically guided endoscope. We validated this estimator in both dynamic simulations and on a physical platform. We then used this estimate in a feed-forward control scheme and demonstrated improved trajectory following. This methodology can enable the use of inverse-dynamic control for the tip-based actuation of an endoscope, without the need for shape sensing.

On the Mechanics of Periodic Motion and Control of Tethered Satellite System in Elliptical Orbit

This study investigates the periodic motions of an in-plane tethered satellite system in elliptical orbits. The equations of motion of the system are derived, and periodic solutions are obtained by perturbation method. Then, the stability properties of the periodic solutions are studied. Analysis results show that the periodic solutions become unstable when orbital eccentricity is larger than a critical value. Two classical control schemes are used to convert the unstable periodic motions to stable ones. Stability analyses of periodic solutions of the two controlled systems show that the two control methods can improve the critical value of orbital eccentricity. Numerical simulations of the controlled system are carried out to demonstrate the validity of the stable region.

THE ANALYSIS OF STOCHASTIC PROCESSES IN UNLOADINGTHE ENERGYWILLOW CUTTINGS FROM THE HOPPER

The paper deals with the theoretical and experimental investigation of the main characteristics of woody crop cuttings unloading from the hopper. To create a variety of automated systems for material feed there is a need to ensure high performance selecting and unloading the material, in particular, it is of vital importance in designing machines for energy willow planting. The analysis of existing theories in mechanics of loose materials motion made it possible to identify the features of unloading the cuttings that narrowed the area of discussion. We will consider two half-planes located at angles to the horizontal plane as a model for hopper in pilot testing. It is analytically and experimentally determined that woody crops cuttings flow occurs according to dry friction laws and inverse-square law and the flow is normal in nature. The statically stable formation and dynamic arches that prevent the uniform and continuous unloading are in evidence. For the theoretical validation of results, we present a set of cuttings as the pseudo liquid that consists of two phases: a discrete phase formed by cuttings and the continuous phase (gaseous medium, air). Each of these phases in terms of the mechanics of multiphase systems is represented as a solid medium with certain characteristics. According to these assumptions, the process unloading of such structure from the hopper can be modelled on the basis of methods of hydrodynamics of multiphase systems. In such a case the field speeds of such pseudo liquid must satisfy the Navier-Stokes equation type. The analytical and empirical analysis of unloading the energy willow cuttings helps to prove theoretically the possibility of enhancing the process of planting till its full automation. As a result, the study gives the theoretical formula that evaluates the velocity of energy willow cuttings flow, the adequacy of which is partially tested in pilot experiments conducted by the authors of the paper in the process of creating the planting machine. Using the received data for further research will make it possible to take into account all the factors involved in unloading and bridging, which is important for examining and improving this process.

The collusion of flexoelectricity and Hopf bifurcation in the hearing mechanism

How do the weak sound waves get amplified in a cochlea? This deceptively simple question has attracted a fair amount of attention and several creative mechanisms have been proposed that purport to understand how the inner ear’s hair cells actively collude to achieve the requisite sensitivity, frequency selectivity, range and nonlinear amplification. Some of the proposed mechanisms target the nature of the mechanoelectric transduction mechanism while others adopt a more dynamical systems approach and focus on the fact that stereocilia of the hair cells operate on the verge of an instability phenomenon—the so-called Hopf bifurcation. In this work, we propose a physics-based model to understand how flexoelectricity, a universal electromechanical coupling that exists in all dielectric substances, facilitates the mechanics of the active motion of hair bundles. A key feature of our model is that we eschew a “black-box” approach, and all parameters are well-defined physical quantities such as membrane bending modulus, geometrical characteristics and others. Furthermore, the model is derived from the well-accepted principles of mechanics and soft matter physics. While the role of flexoelectricity in the hearing mechanism has been noted before, we show for the first time that flexoelectricity is an essential ingredient in inducing the Hopf bifurcation state considered responsible for several highly nonlinear and peculiar features of the hearing mechanism. We find that the biomembranes’ bending modulus and the intracellular charge concentration (which for instance could represent K+ or Ca2+) are the two key control parameters that significantly impact the stability of the system and hence the hearing mechanism. Our work highlights the importance of flexoelectricity, confirms earlier assertions that the cochlea amplifies the acoustic stimuli through its exceptional electromechanical energy conversion property, and provides insights into how physical properties such as biomembranes’ bending modulus impact the performance of the hearing system.