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Simulations of human body motion involve different fields of study such as robotics, from nano to macroscale, and biomechanics. The simulation of human motion is a challenging problem from the physical and computational perspectives and several models have been proposed in literature. Using a methodology named predictive dynamics, this work aims to propose a 2D spatial model of human walking during the single stance phase (SSP), using a flat foot adaptation. The model is based on inverse dynamics in which the angular displacements are interpolated by 5th degree B-splines. The equation of motion is developed by the recursive Lagrangian formulation due to its computational efficiency. An optimization problem is set up to obtain the control points of the B-splines using as the objective function the dynamic effort, which is a limited power supply. The constraints imposed on the motion are time-dependent, such as the torque/angle limits, and the dynamic stability criterion defined by the zero moment point (ZMP), or time-independent, such the equation of motion and step length. All the steps are explained in detail to find the dynamics of the body using the smallest number of laboratory results. The solution from the model is favorably compared to Winter’s data, in particular the ground reaction forces, which is important in many engineering applications.

Derivatives of equations of motion (EOM) describing the dynamics of rigid body systems are becoming increasingly relevant for the robotics community and find many applications in design and control of robotic systems. Controlling robots, and multibody systems comprising elastic components in particular, not only requires smooth trajectories but also the time derivatives of the control forces/torques, hence of the EOM. This paper presents the time derivatives of the EOM in closed form up to second-order as an alternative formulation to the existing recursive algorithms for this purpose, which provides a direct insight into the structure of the derivatives. The Lie group formulation for rigid body systems is used giving rise to very compact and easily parameterized equations.

In the present study, the dynamics of the tendon system of a tension-leg platform (TLP) is investigated through the absolute nodal coordinate formulation (ANCF). Based on the energy conversion principle, the stiffness, generalized elastic force, external load and mass matrices of the element are deduced to perform the element assembling by using the finite element method. Then the motion equation of the tendon/riser is established. In this study, the TLP in the International Ship Structures Committee (ISSC) model under the first and second wave forces is considered as the case study. The simulation is performed in the MATLAB environment. Moreover, the accuracy and reliability of the programs are verified for cases of beam model with theoretical solutions. It is found that the motion response of tendons is affected by the TLP movement and environmental load, simultaneously. Then, the motion response is calculated using the SESAM software and exported as the boundary of ANCF tendons. Finally, the static and dynamic characteristics of the four tendons of ISSC TLP are analyzed systematically by the ANCF method. Performed analysis proves the effectiveness and feasibility of the ANCF method. It is concluded that the proposed method is a powerful scheme for calculating the dynamics of tendon/riser in the field of ocean engineering.

Light-field microscopy has emerged as a technique of choice for high-speed volumetric imaging of fast biological processes. However, artifacts, nonuniform resolution and a slow reconstruction speed have limited its full capabilities for in toto extraction of dynamic spatiotemporal patterns in samples. Here, we combined a view-channel-depth (VCD) neural network with light-field microscopy to mitigate these limitations, yielding artifact-free three-dimensional image sequences with uniform spatial resolution and high-video-rate reconstruction throughput. We imaged neuronal activities across moving Caenorhabditis elegans and blood flow in a beating zebrafish heart at single-cell resolution with volumetric imaging rates up to 200 Hz. Reconstruction of light-field microscopy data with a deep-learning network achieves high reconstruction speed and reduces artifacts, as illustrated for moving C. elegans and beating zebrafish hearts.

A method for monitoring cell population movement in microscopic video-sequences based on integral optical flow and motion maps is proposed. Through adjustment and calibration of the optical system and averaging consecutive frames, high-quality subsequent images are obtained. Short-term dynamic characteristics are determined by optical flow. Based on optical flow, integral optical flow is calculated and used to create motion maps, and these maps are used to analyze and describe motions in any region of interest. Therefore, different types of cell movements, including directional motion, aggregation and dispersion can be identified. The proposed method does not require training, it can be used for situation monitoring and analysis, or as a component of comprehensive systems. Experiments performed on synthesized and real microscopic video images demonstrate the effectiveness of this method.

Dynamical systems with position varying mass are archetypal examples of classical mechanical systems with rocket engine being a typical realistic model. In the present study, we extend the classical Newtonian mechanics by replacing the kinetic energy by a nonlocal-in-time kinetic energy and the standard velocity by a fractional velocity. These replacements lead to an extension of Newton’s second law of motion which has interesting implications in incompressible fluid dynamics. As an application, we discuss the rotating fluid problem subject to a position varying fluid mass which occurs in rocket dynamics. Several features were observed, mainly the transition from order to disorder in rotating fluids in rockets.

In discrete dislocation dynamics (DDD) simulations dislocation-induced stress fields and dislocation–dislocation interaction forces are typically evaluated using analytically described multiparameter continuous functions. The universal approximation theory guarantees the approximation of such functions by some machine learning (ML) techniques, which in turn can potentially help to accelerate DDD simulations. However, accurate machine approximation is as crucial as its acceleration. Here, we demonstrate the feasibility of utilizing deep neural networks to predict dislocation-induced stress fields and dislocation–dislocation interaction forces. We also show that the trained network produces estimates that are in very good agreement with analytical solutions. This was only plausible by generating an enriched data repository to avoid bias in the training data. This work opens the door to further development of more optimized ML architectures that could lead to a more computationally efficient, yet accurate, approach to replace the generally inefficient analytical calculations of dislocation–dislocation interaction forces in DDD simulations.

In this paper, a model of active control system with state-dependent actuation time delay is investigated. Galerkin projection scheme is used to obtain its low dimensional approximation system. State-dependency and effect on dynamics and performance of actuation delay in this active control system are considered. The following results are obtained. Firstly, a state-dependent actuation delay is proposed, which has never been reported in the previous works. It displays that actuation delay is state-dependent. Secondly, employing Galerkin projection scheme, low dimensional approximation system of this delayed active control system is obtained. At last, its stability and Hopf bifurcation are investigated by Routh-Hurwitz Criterion and Hopf bifurcation theory. Using software WinPP, numerical simulation is executed and supports the theoretical results in this paper.

This paper presents a control strategy to enhance the lateral dynamics stability and handling performance of the four-wheel independently actuated (FWIA) electric vehicles (EVs). The vehicle longitudinal velocity uncertainty and controller saturation are considered, a double layers control scheme is adopted. In the upper layer, the homogeneous polynomial parameter-dependent approach is introduced to track the uncertainty problem, and a multi-objective controller is designed to obtain the desired external yaw moment. In the lower layer, an optimal force distribution method with considering the distribution error and tire workload is employed to allocate the desired external yaw moment into forces of the four in-wheel motors. Simulation results verify the effectiveness of the proposed control strategy.

This paper reports the results of study of the influence of gas content in working fluid on the dynamics of hydraulic drive of equipment for oil and gas well development. A mathematical model of the hydraulic drive obtained in the Cauchy form is proposed. The dependence of piston speed, pressure in the piston chamber of the hydraulic cylinder, and pressure in the rod chamber of the hydraulic drive on time at 0 and 8% undissolved gas content in the fluid is established.

We investigate the transport of excitons and trions in monolayer semiconductor WS$_2$ subjected to controlled non-uniform mechanical strain. We actively control and tune the strain profiles with an AFM-based setup in which the monolayer is indented by an AFM tip. Optical spectroscopy is used to reveal the dynamics of the excited carriers. The non-uniform strain configuration locally changes the valence and conduction bands of WS$_2$, giving rise to effective forces attracting excitons and trions towards the point of maximum strain underneath the AFM tip. We observe large changes in the photoluminescence spectra of WS$_2$ under strain, which we interpret using a drift-diffusion model. We show that the transport of neutral excitons, a process that was previously thought to be efficient in non-uniformly strained 2D semiconductors and termed as "funneling", is negligible at room temperature in contrast to previous observations. Conversely, we discover that redistribution of free carriers under non-uniform strain profiles leads to highly efficient conversion of excitons to trions. Conversion efficiency reaches $\simeq 100\%$ even without electrical gating. Our results explain inconsistencies in previous experiments and pave the way towards new types of optoelectronic devices., 6 pages, 4 figures

There are several methods (empirical, statistical, and machine learning tools) to calculate blast-induced ground vibration. Still, due to complications in the blasting procedure, under varying blasting loads and strata conditions, it is not easy to predict and simulate blast vibration precisely. Therefore, a study was conducted to simulate the field blast data in Ansys software using explicit dynamics. For this study, monitoring of ground vibration for 20 single hole blasts was carried out. The density of emulsion explosives was in the range of 0.9 to 1.15 g/cc. In the laboratory, rock properties were determined from the rock sample collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and the density of the emulsion explosive were also determined. These parameters were used for numerical analysis to know the ground vibrations at specified points. The results of ground vibration predicted by the model are validated using field data.

This paper aims to research the cable-lead-in rod effect on a towed system through mathematical modeling and numerical simulations. The rod dynamics, as a key part of this study, is modeled using the combination of cable node governing equations and kinematic constraint conditions. As the first attempt to analyze such a problem, the rod is simply treated as an elastic cable segment so as to be incorporated into the dynamics of the cable, and a set of algorithm is then proposed based on the kinematic constraint conditions to fully describe its motions. Meanwhile, the cable and the underwater vehicle are modeled by the traditional lumped mass method and the 6 degree-of-freedom maneuverability equations for submarines respectively; the coupling boundary conditions besides the rod dynamics are also given to form the whole system’s model. Several numerical cases are performed to investigate the rod effect on the system in different maneuver situations. Some meaningful conclusions are drawn through comparative analysis.

The breakage of rock mass by blasting has many challenges. The optimal breakage in an underground development face/tunnel blast is dominantly dependent on the relief area provided to the blast holes. The cut portion in the burn cut face blast is significantly important to achieve the controlled deformation due to the blast. This paper has discussed the impact of the number and diameter of the relief holes on the breakage pattern of the rock. The numerical simulation with varying numbers and diameter of relief hole was carried out for this purpose. Finite element modeller explicit dynamics of Ansys-Autodyn was used for the simulation work. The isosurface of non-deformed zone was plotted to compare the extent of deformation under varying conditions of relief holes. The analysis shows that the higher number of relief holes with optimum diameter gives more controlled deformation than single relief hole with larger diameter. The nearfield vibration was also recorded by placement of seismograph. The waveform analysis of the recorded vibration was carried out. The redesigning of the blasting pattern was done using the results of numerical simulation and waveform analysis. The redesigned pattern consists of four relief holes of 115 mm diameter. The blasting output with the revised design has resulted into the considerable improvements in the pull and reduction of overbreak. The revised pattern has addressed the issue of the socket formation at the site.

The Hamiltonian for a system of two two-level atoms separately located in two cavities coupled through the overlap of the evanescent cavity fields in presence of an external classical fields is introduced. It is simplified by using unitary canonical transformations for both the atomic and photonic modes. The atomic population inversion and the degree of entanglement are considered. Different interactions are addressed within a temporal evolution of the system in correspondence with three dispersive regimes limits. Analytical expressions of the coefficients of the time dependent wavefunctions of the different Hamiltonians are derived. The influences of the photon hopping strength, detuning and the couplings of the external classical fields on the behavior of the atomic population inversion and the atomic entropies and degree of entanglement are investigated. The interrelation between the 1st-atom entanglement and the atomic population inversion is noted. General conclusions reached are illustrated through numerical results.

Flow-diverting stents (FDS) are used to treat cerebral aneurysms. They promote the formation of a stable thrombus within the aneurysmal sac and, if successful, isolate the aneurysmal dome from mechanical stresses to prevent rupture. Platelet activation, a mechanism necessary for thrombus formation, is known to respond to biomechanical stimuli, particularly to the platelets’ residence time and shear stress exposure. Currently, there is no reliable method for predicting FDS treatment outcomes, either a priori or after the procedure. Eulerian computational fluid dynamic (CFD) studies of aneurysmal flow have searched for predictors of endovascular treatment outcome; however, the hemodynamics of thrombus formation cannot be fully understood without considering the platelets’ trajectories and their mechanics-triggered activation. Lagrangian analysis of the fluid mechanics in the aneurysmal vasculature provides novel metrics by tracking the platelets’ residence time (RT) and shear history (SH). Eulerian and Lagrangian parameters are compared for 19 patient-specific cases, both pre- and post-treatment, to assess the degree of change caused by the FDS and subsequent treatment efficacy.

This paper represents an explicit analytical solution for attitude dynamics of spacecraft combination during on-orbit refueling. Due to the fuel transfer from the servicer to the client, the inertia tensor of the spacecraft combination varies in time, which evidently leads to an inner disturbance torque on the attitude motion. Firstly, the variation of the inertia tensor matrix is formulated in terms of fuel transfer rate, and the refueling disturbance torque associated with the variation of inertia tensor is analyzed. Secondly, with an additional consideration of the effect from gravity gradient, the behavior of attitude dynamics during and after fuel transfer is investigated. Finally, different scenarios are simulated to demonstrate the efficiency of the proposed model. The result in this work is important and allows for evaluations on the attitude disturbance and stability for an on-orbit refueling mission.

In this paper, deployment dynamics of a large-scale flexible solar array system on the ground is investigated. Firstly, the structure of the ground solar array system adopted in this paper is introduced. Then kinematic description of a single flexible body and kinematic constraint equations of two flexible bodies are both deduced. Next dynamic equation of the ground solar array system is established by the Jourdain velocity variation principle. Finally, the validity of the dynamic model is verified through comparison with the ADAMS software. Simulation results indicate that the proposed dynamic model is effective to describe the deployment dynamics of the flexible solar array system on the ground.

In this paper, a dynamics equation for Spacecraft has first been created using vector mechanics. Second, several attitude dynamics equations of spacecraft have been deduced. Third, a simulation of the coupled structure vibration–attitude dynamics evolution of China Space Station has been researched. Simulation results reveal the generating mechanism and evolutive law of the coupled structure vibration–attitude dynamics of spacecraft. Finally, a simplified experimental platform has been set up, and the experimental results verify the structure vibration–attitude dynamics evolution of the spacecraft and proposed experimental setup.

The paper presents the application of the finite segment method to the analysis of coupled bending torsional vibrations of risers. The method is formulated by means of joint coordinates using multibody methods for kinematics and dynamics. A new approach to calculating bending and torsion moments is presented. The mathematical model and computer program enable us to analyse both free and forced vibrations of risers caused by the motion of the base (vessel or platform) as well as hydrodynamic forces. The model is validated by comparing frequencies of free and forced vibrations calculated from the authors’ own models with the results presented by other researchers. Natural frequencies are also compared with analytical solutions. The influence of sea currents and of the initial twisting of the riser on its natural and forced vibrations is analysed.

In the neural progenitors of the developing central nervous system (CNS), cell proliferation is tightly controlled and coordinated with cell fate decisions. Progenitors divide rapidly during early development and their cell cycle lengthens progressively as development advances to eventually give rise to a tissue of the correct size and cellular composition. However, our understanding of the molecules linking cell cycle progression to developmental time is incomplete. Here, we show that the microRNA (miRNA) let-7 accumulates in neural progenitors over time throughout the developing CNS. Intriguingly, we find that the level and activity of let-7 oscillate as neural progenitors progress through the cell cycle by in situ hybridization and fluorescent miRNA sensor analyses. We also show that let-7 mediates cell cycle dynamics: increasing the level of let-7 promotes cell cycle exit and lengthens the S/G2 phase of the cell cycle, while let-7 knock down shortens the cell cycle in neural progenitors. Together, our findings suggest that let-7 may link cell proliferation to developmental time and regulate the progressive cell cycle lengthening that occurs during development.

In the paper, based on the linear Schrodinger equation, we analytically investigate the effect of initial chirp on the dynamics of the optical beam in a medium with the parabolic potential. For the linear chirp, the results show that the linear chirp of beam can induce a periodically oscillating behavior, where the oscillating amplitude is proportional to the linear chirp parameter, and the beam’s peak and width are related to the depth of parabolic potential. For the quadratic chirp, the results show that the quadratic chirp of beam can induce a periodically breathing behavior and affect the evolution of beam’s peak and width.

Nearly all studies of angiogenesis have focused on uni-family ligand-receptor binding, e.g., VEGFs bind to VEGF receptors, PDGFs bind to PDGF receptors, etc. The discovery of VEGF-PDGFRs binding challenges this paradigm and calls for investigation of other ligand-receptor binding possibilities. We utilized surface plasmon resonance to identify and measure PDGF-to-VEGFR binding rates, establishing cut-offs for binding and non-binding interactions. We quantified the kinetics of the recent VEGF-A:PDGFRβ interaction for the first time with K

Luna 3 (or Lunik 3 in Russian sources) was the first spacecraft to perform a flyby of the Moon. Launched in October 1959 on a translunar trajectory with large semimajor axis and eccentricity, it collided with the Earth in late March 1960. The short, 6-month dynamical lifetime has often been explained through an increase in eccentricity due to the Lidov–Kozai effect. However, the classical Lidov–Kozai solution is only valid in the limit of small semi-major axis ratio, a condition that is satisfied only for solar (but not for lunar) perturbations. We undertook a study of the dynamics of Luna 3 with the aim of assessing the principal mechanisms affecting its evolution. We analyze the Luna 3 trajectory by generating accurate osculating solutions, and by comparing them to integrations of singly and doubly averaged equations of motion in vectorial form. Lunar close encounters, which cannot be reproduced in an averaging approach, decisively affect the trajectory and break the doubly averaged dynamics. Solar perturbations induce oscillations of intermediate period that affect the geometry of the close encounters and cause the singly averaged and osculating inclinations to change quadrants (the orbital plane “flips”). We find that the peculiar evolution of Luna 3 can only be explained by taking into account lunar close encounters and intermediate-period terms; such terms are averaged out in the Lidov–Kozai solution, which is not adequate to describe translunar or cislunar trajectories. Understanding the limits of the Lidov–Kozai solution is of particular significance for the motion of objects in the Earth–Moon environment and of exoplanetary systems.

On-chip fluorescence imaging devices are recognized for their miniaturized and implantable nature that can benefit the study of intracellular dynamics at a variety of settings. However, it is challenging to integrate a spectral filter onto such devices (to block the excitation light) that has similar performance to the state-of-the-art emission filters used in fluorescence microscopes. In this work, we report a 100%-yield, spectrally filtered passive Si photodiode array designed for on-chip fluorescence imaging of intracellular Ca

Cancer is still a disease with many unknowns. In this paper, we developed a study on the proliferation of tumor cells under chemotherapeutic treatment and the influence of integrative oncology on these results. Initially, we analyzed mathematically tumor behavior, using the Gompertz model, with and without chemotherapeutic treatment. We observed the variation of the immune system and tumor cell fighter cells directly associated with the integrative treatment through the noetic threshold. We analyzed tumor cell behavior, associated with the immune system, especially after treatment completion. The uncertainties under the parameters used led us to use the fuzzy theory and with that also define the fuzzy noetic threshold. We inserted the possibility of resistant cells to the chemotherapeutic treatment and studied the optimal control with this treatment. We also considered the values of the initial conditions, the node threshold, and the resistant cells by fuzzy numbers.

This paper presents a new mathematical model of 4 degrees of freedom of links to qualitatively describe the dynamic behavior of the front structure of an excavator. In the model, the effects of couple of forces as new additional effects are involved. The exact forms and solutions for position-varying moments of inertia used in this model are presented. A topologic structure is used for the kinematic analysis of the body frame. The numerical results show that the new additional effects can change the angular kinetic energy of all links to a significant degree when the upper structure swings. The results suggest that the new additional effects should be taken into account for analysis of excavator dynamics.

This study proposes a new car-following model considering the effects of the electronic throttle dynamics to capture the characteristics of connected autonomous vehicular traffic flow without lane discipline. In particular, the proposed model incorporates the effects of both electronic throttle opening angle and lateral gap into the traffic flow model by assuming that the information on electronic throttle dynamics is shared by surrounding vehicles through vehicle-to-vehicle communications. Stability of the proposed model is analyzed using the perturbation method. Numerical experiments analyze three scenarios: start, stop and evolution processes for the scenarios of lane-discipline-based full velocity difference (FVD) model, non-lane-based full velocity difference car-following (NLBCF) model and non-lane-discipline and throttle-based car-following model, respectively. Results from numerical experiments illustrate that the proposed car-following model has a larger stale region compared with the FVD and NLBCF models. In addition, it also demonstrates that the proposed car-following model can better represent the characteristics of connected and autonomous vehicular traffic flow in terms of the responsiveness, smoothness and stability with respect to the position, velocity, acceleration/deceleration and space headway profiles.

This study aims to investigate the capability of smoothed particle hydrodynamics (SPH), a fully Lagrangian mesh-free method, to simulate the bulk blood flow dynamics in two realistic left ventricular (LV) models. Three dimensional geometries and motion of the LV, proximal left atrium and aortic root are extracted from cardiac magnetic resonance imaging and multi-slice computed tomography imaging data. SPH simulation results are analyzed and compared with those obtained using a traditional finite volume-based numerical method, and to in vivo phase contrast magnetic resonance imaging and echocardiography data, in terms of the large-scale blood flow phenomena usually clinically measured. A quantitative comparison of the velocity fields and global flow parameters between the in silico models and the in vivo data shows a reasonable agreement, given the inherent uncertainties and limitations in the modeling and imaging techniques. The results indicate the capability of SPH as a promising tool for predicting clinically relevant large-scale LV flow information.

Impact of droplets on rough surfaces has many industrial applications. Various types of splashing and spreading of liquid droplets result due to impingement of the droplets on the different surfaces incorporating formation of satellite droplets. Dynamics of splashing and spreading is different with respect to the point of impact—groove or hill—on the grooved surface. Physics of spreading of impacted droplets on the curved-grooved surfaces is not known so far. Impact of droplets on curved-grooved surface has been studied for a narrow range of Weber number to know the abrupt change in projected area of splashed droplets. Such abrupt change in the geometry of splashed droplets due to exaggerated elongation in the direction of groove was observed for narrow range of Weber numbers from 42 to 45. The present findings explore new direction for further fundamental research work to comprehend the physics of dynamics of impacted droplets for development of new theory helpful for spray painting, printing, and designing of shielding structures.

The global spread of Electric Bicycles (EBs) is increasing more and more. In addition to supporting the ease of cycling, the electric energy available can also be used for innovative braking control systems. The project BikeSafe picks up on this idea and aims at developing an active Braking Dynamics Assistance system (BDA) for EBs equipped with hydraulic brakes. A simulation model taking into account all substantial braking dynamics influences is necessary for the model-based design of the BDA. This paper presents a Multi-Body Model (MBM) of a front suspension bicycle and a passive rider. This MBM has been experimentally validated for in-plane braking dynamics using road tests. It has real-time ability and can therefore be used as a virtual representation of the plant for the model-based design process of the BDA.

A method of numerical modeling is used to solve three most interesting problems of artificial Earth satellite (AES) dynamics. Orbital evolution of an ensemble of near-Earth objects at altitudes in the range from 1 500 to 60 000 km is considered, chaoticity of motion of objects in the geosynchronous zone is studied by the MEGNOanalysis, the parameters of AES motion are determined, and the models of forces are considered from measurements for GLONASS satellites. The recent versions of algorithms and programs used to perform investigations are briefly described.

This paper presents a study of the dynamic behavior of a planar four-bar mechanism with clearance. A spring was added to improve the dynamic response of the mechanism with clearance. Simulations and experimental tests were carried out to show the improvement of the dynamic behavior using this simple yet effective solution. The simulation was performed under MATLAB and ADAMS. An experimental set-up was designed and built to achieve the experimental validations. The presented results show that the added spring improved the dynamic behavior of the mechanism by keeping a continuous contact between the journal and the sleeve despite the presence of the clearance. The effect of the spring on the input torque was also investigated. It is shown that the spring increases the maximum value of the torque. Optimization was performed to determine the best parameters of the spring that reduce the effect of the clearance while minimizing the increase of the input torque. The optimized system was tested at different speeds to show the effect of the speed on the dynamic behavior of the optimized system.

A procedure and software for studying the dynamics of a reinforced cylindrical shell on an elastic foundation are developed. The shell is under local loads distributed over small areas and varying linearly during a short time. The stringers are described by a structurally orthotropic model and the ring ribs by a discrete model. The candidate solution is expanded into series of natural modes. The influence of a local load on the deformation parameters of the shell is studied using a test example. Conclusions on the effect of the pulse shape, the time of action of the external forces, and the reinforcement on the strain state of the shell are drawn

This study aimed to dynamically analyze a simulated bimodal tram by determining the motion equations for computer-aided analysis with Newton-Euler equations of motion, which algebraically represent motion. We utilized the multi-body dynamics analysis program, MSC.Adams, to evaluate the equations of motion, running stability, curving performance, and ride comfort of the simulated bimodal tram in comparison with single fleet and double fleet trams. For the double fleet tram, the characteristic equation was deduced to control the all-wheel steering mechanism by independently moving all the wheels characterizing an articulated vehicle. Our study aimed to design a double fleet bimodal tram. We confirmed that domestic and international standards were satisfied via the design and analysis of the simulation. Steering control equations are the significant preliminary data for coupling device research and development for double fleet bimodal trams.

In this paper, we sought to develop a valid theoretical model of two bridges coupled via their dynamic environment modelled as a linear viscoelastic Winkler foundation. Analytical, numerical and experimental study of the dynamic response of the two bridges are explored in the cases where they are submitted to sinusoidal excitation and periodic impulsive force. The effects of the close environment and the distance between the two bridges on the amplitude of vibration of each beam bridge is pointed out.

Analyzing the characteristics of force and tool vibration trajectories during stable and unstable milling processes provides information such as the shape, orientation, and sense of rotation of these trajectories; such information facilitates positively identifying machine chatter. This paper presents analytical models for determining the forces and tool tip displacement during stable and unstable milling with axis-symmetrical structural dynamics. The trajectory of nominal milling forces under both stable and unstable cutting conditions was demonstrated to run clockwise in an elliptical path, with the dynamic forces during chatter running counterclockwise. The tool tip displacements demonstrated the same trajectory pattern as the milling forces. Both the nominal and dynamic forces had similar modal directions, pointing to the right and left sides of the x axis for up and down-millings, respectively. The predictions of the force and tool tip displacement trajectories in stable milling and during chatter were verified using numerical simulations and validated in experiments.

A linear oscillating motor is an electromagnetic actuator that can achieve short-stroke reciprocating movement directly without auxiliary transmission mechanisms. It has been widely used in linear pump applications as the source of power and motion. However, because of the demand of high power density in a linear actuation system, the performance of linear oscillating motors has been the focus of studies and deserves further research for high power density. In this paper, a general framework of linear oscillating motor design and optimization is addressed in detail, including the electromagnetic, dynamics, and thermal aspects. First, the electromagnetic and dynamics characteristics are modeled to reveal the principle for optimization. Then, optimization and analysis on magnetic structure, resonant system, and thermal features are conducted, which provide the foundation for prototype development. Finally, experimental results are provided for validation. As a whole, this process offers complete guidance for high power density linear oscillating motors in linear pump applications.

A serial-parallel dynamics simulator based on serial-parallel manipulator is proposed. According to the dynamics simulator motion requirement, the proposed serial-parallel dynamics simulator formed by 3-RRS (active revolute joint-revolute joint-spherical joint) and 3-SPR (Spherical joint-active prismatic joint-revolute joint) PMs adopts the outer and inner layout. By integrating the kinematics, constraint and coupling information of the 3-RRS and 3-SPR PMs into the serial-parallel manipulator, the inverse Jacobian matrix, velocity, and acceleration of the serial-parallel dynamics simulator are studied. Based on the principle of virtual work and the kinematics model, the inverse dynamic model is established. Finally, the workspace of the (3-RRS)+(3-SPR) dynamics simulator is constructed.

It is shown that the general dynamics factor governing strength calculations of metallic spans is determined by the soil conditions and particularities of the interaction between support foundations and bases. The influence of the soil conditions for transverse oscillations of bridges increases with increasing support height and decreasing deformation characteristics of the base. It is noted that in order to make span structures more earthquake-resistant the foundation can be developed without changing the elements of the span structure.

In this paper, a new model for the cutting force during the bandsawing process is presented by studying its steady and dynamic properties. Considering the sawing and no-sawing states, a single-tooth cutting force model with steady behavior was built. Then, this model was optimized by considering the intermittent feed motion of the bandsaw frame and the instantaneous chip thickness. Finally, a universal dynamic multi-tooth cutting force model with variable tooth pitch was obtained by introducing three periodic characteristics, i.e., single tooth, tooth set, and bandsaw blade transmission. Simulations and experiments verified the proposed model for intermittent feed motion, steady-state characteristics conditions, and cutting force dynamics. The errors in three characteristic frequencies between the simulations and experiments in the cutting force signal were less than 0.059 Hz. Moreover, the dynamic characteristics of the cutting force were primarily affected by the number of sawing teeth that engaged in sawing, intermittent feed motion, and variations in tooth pitch. In addition, the cutting force was approximately proportional to the number of teeth engaged in sawing, and three periodic characteristics of the cutting force were found to be common in the bandsawing process.

Grazing bifurcation might bring dramatic and abrupt qualitative changes of system responses in non-smooth systems. The control problem of near-grazing dynamics in a two-degree-of-freedom vibro-impact system with a clearance is addressed in this paper. The discontinuity mapping is built to derive a normal form map near the grazing point. Based on the stability criterion of grazing orbit formulated through the normal form map, a discrete-in-time feedback method is developed to control the stability of grazing orbit in the vibro-impact system. Numerical simulations reveal a discontinuous grazing bifurcation with a jump between the transitions of periodic motions and show the feasibility of the proposed control strategy.

The B-plane is a fundamental tool to analyze planetary encounters of small bodies and spacecraft flybys. In this paper, we review the B-plane formulation with a full derivation of its coordinates and their partial derivatives, which allow the mapping of orbital uncertainties onto the B-plane. We find that this mapping can be sensitive to variations in the inbound asymptote, especially for low-velocity encounters, and to non-Keplerian dynamics for distant encounters. Under linearity assumptions, we show how to derive close approach boundaries and impact probabilities from the orbital uncertainty mapped onto the B-plane.

This paper presents for the first time a numerical prediction of the thrombogenic potential by means of partial differential equation in computational fluid dynamics for cardiovascular devices. To quantify the thrombogenic potential was developed the Platelet Lysis Index equation in an Eulerian model. Six different catheter tip models with the results obtained from the literature, however, with Lagrangian approach were compared. Three-dimensional computational fluid dynamics was done with a realistic central venous catheter model. The partial differential equation covers the entire computational domain, allowing the visualization of the regions with the highest platelet activation. In the realistic catheter, the first arterial proximal hole was the region with the highest Platelet Lysis Index and shear rate. Despite all limitations and considerations, the use of the Eulerian model allows a quick numerical comparison of the thrombogenic potential of cardiovascular device, being a useful tool in its design.

Wealth and income distributions are known to feature country-specific Pareto exponents for their long power-law tails. To propose a rationale for this, we introduce an agent-based dynamic model and use Monte Carlo simulations to unveil the wealth distributions in closed and open economical systems. The standard money-exchange scenario is supplemented with the position-exchange agent dynamics that vitally affects the Pareto law. Specifically, in closed systems with position-exchange dynamics the power law changes to an exponential shape, while for open systems with traps the Pareto law remains valid.