General Kinematic Research Articles

Benchmarking of a 3D non-linear lifting line method against 3D RANSE simulations

As a part of the design and operation of kites as auxiliary propulsion of vessels, it is necessary to be able to quickly estimate the aerodynamic efforts along various trajectories. A 3D non-linear model based on the lifting line of Prandtl has been developed for this purpose. It allows these rapid calculations for wings with any laws for the dihedral angle, the twist, and the sweep angle, along the span, and for a general flight kinematic taking into account translation velocities and rotation rates. This model has been verified by comparison with 3D simulations performed with a Navier-Stokes solver. It gives satisfactory results in incidence and sideslip, with gaps of about 4% for forecasts lift. Special attention has been paid to the estimation of the accuracy of the provided numerical results.

Simulation and adaptive control of back propagation neural network proportional–integral–derivative for special launcher using new version of transfer matrix method for multibody systems

Rocket launcher system, as a special launcher placed on tactical vehicles, is a very complex mechanical system with characteristics of strong shock and vibration. In order to improve position accuracy, as well as reduce vibration, this paper creates a nonlinear dynamics model of the launcher system by using a new version of the transfer matrix method for multibody systems. The overall transfer equation of the nonlinear model is deduced. Combining with general kinematics equations of the rocket, the system launch dynamics are simulated and compared with experiments to verify the correctness of the model. On this basis, a backpropagation neural network proportional–integral–derivative adaptive control system is designed to improve servo control of the launcher. Then, the effectiveness of this method is verified by comparing with the traditional proportional–integral–derivative control method. Simulated results show that the backpropagation neural network proportional–integral–derivative control system makes the azimuth and elevation angles reach the target values smoothly and quickly, with higher accuracy. The results prove that the proposed method prominently reduces vibrations of the launcher, by adjusting the control parameters online according to the operation state of the system, presenting a better stability and robustness.

Well-posedness of a one-dimensional nonlinear kinematic hardening model

<p style='text-indent:20px;'>We investigate the quasistatic evolution of a one-dimensional elastoplastic body at small strains. The model includes general nonlinear kinematic hardening but no nonlocal compactifying term. Correspondingly, the free energy of the medium is local but nonquadratic. We prove that the quasistatic evolution problem admits a unique strong solution.

Is Swimmers' Performance Influenced by Wetsuit Use?

To observe changes in performance, physiological, and general kinematic variables induced by the use of wetsuits vs swimsuits in both swimming-pool and swimming-flume conditions. In a randomized and counterbalanced order, 33 swimmers (26.46 [11.72]y old) performed 2 × 400-m maximal front crawl in a 25-m swimming pool (with wetsuit and swimsuit), and their mean velocities were used later in 2 swimming-flume trials with both suits. Velocity, blood lactate concentration, heart rate (HR), Borg scale (rating of perceived exertion), stroke rate, stroke length (SL), stroke index, and propelling efficiency were evaluated. The 400-m performance in the swimming pool was 0.07m·s-1 faster when using the wetsuit than when using the swimsuit, evidencing a reduction of ∼6% in time elapsed (P < .001). Maximal HR, maximal blood lactate concentration, rating of perceived exertion, stroke rate, and propelling efficiency were similar when using both swimsuits, but SL and stroke index presented higher values with the wetsuit in both the swimming pool and the swimming flume. Comparing swimming conditions, maximal HR and maximal blood lactate concentration were lower, and SL, stroke index, and propelling efficiency were higher when swimming in the flume than when swimming in the pool with both suits. The 6% velocity improvement was the result of an increase of 4% in SL. Swimmers reduced stroke rate and increased SL to benefit from the hydrodynamic reduction of the wetsuit and increase their swimming efficiency. Wetsuits might be utilized during training seasons to improve adaptations while swimming.

Gravitational and tectonic stress states within a deep-seated gravitational slope deformation near the seismogenic Periadriatic Line fault

The role of tectonic horizontal stresses in activating deep-seated gravitational slope deformations (DSGSD) has rarely been studied. We applied a new numerical technique for determining the present-day stress states within a large DSGSD, situated near the Periadriatic Line fault (PAL) in the Eastern Alps. The stress states were calculated from three-dimensional displacements of the sinistral Obir fault conjugated to the dextral PAL fault, which also forms the upper DSGSD detachment plane. The analysed fault displacements occurred in two distinct activity phases associated with the elastic rebound along (i) the Obir fault in the summer of 2014, and (ii) the core of the PAL fault in the winter of 2014/2015. These periods were synchronous with the periods of increased local seismicity. The results brought an insight into a possible causative link between horizontal tectonic stresses and DSGSDs activation. We observed, that transient dextral transpressions and dextral transtensions opposing to the general fault kinematics associated to the elastic rebound had a potential to destabilize the DSGSD at the micrometre level. The applied stress-tensor calculation, although restricted only to shallow near-surface conditions, is a reliable method that can reveal stress states almost in the real-time.

Diffractive dijet production in impact parameter dependent saturation models

We study coherent diffractive dijet production in electron-hadron and electron-nucleus collisions within the dipole picture. We provide semi-analytic results for the differential cross section and elliptic anisotropy in the angle between dijet transverse momentum and hadron recoil momentum. We demonstrate the direct relation between angular moments of the dipole amplitude in coordinate space and angular moments of the diffractive dijet cross sections. To perform explicit calculations we employ two different saturation models, extended to include the target geometry. In the limit of large photon virtuality or quark masses, we find fully analytic results that allow direct insight into how the differential cross section and elliptic anisotropy depend on the saturation scale, target geometry, and kinematic variables. We further provide numerical results for more general kinematics in collisions at a future electron-ion collider, and study the effects of approaching the saturated regime on diffractive dijet observables.

Modeling Parallel Robot Kinematics for 3T2R and 3T3R Tasks Using Reciprocal Sets of Euler Angles

Industrial manipulators and parallel robots are often used for tasks, such as drilling or milling, that require three translational, but only two rotational degrees of freedom (“3T2R”). While kinematic models for specific mechanisms for these tasks exist, a general kinematic model for parallel robots is still missing. This paper presents the definition of the rotational component of kinematic constraints equations for parallel robots based on two reciprocal sets of Euler angles for the end-effector orientation and the orientation residual. The method allows completely removing the redundant coordinate in 3T2R tasks and to solve the inverse kinematics for general serial and parallel robots with the gradient descent algorithm. The functional redundancy of robots with full mobility is exploited using nullspace projection.

The ratio of tectonic structure and modern movements of the crust in area of geodynamic proving ground in Bishkek

According to the various scale GPS measurements, the process of collision between India and Eurasia is still ongoing and is reflected on Central Asia territory. The maximum velocity of shortening on northern component between India and Asia is ∼35 mm/year; the longitudinal (east-west) extension of the Tien Shan is ∼20 mm/year. The maximum deformations of shortening ∼15 mm/year along the north coordinate operate in a narrow fault zone between the Pamir and Tien Shan. Not on all Cenozoic (neotectonic) faults occur modern movements of the earth’s crust, these faults may have separate segments of active at different times. The general kinematic tendencies of modern movements correlate well enough with the general kinematic structure of neotectonic faults. In the fault zones at distances from the first hundreds meters to the first kilometers, intense elastic changes in the baseline lengths up to 4 cm (strains of 10–4) can occur within a week and up to 3-5 months. Such high-frequency elastic events have a different character of manifestations and are 2-4 orders of magnitude greater level than stable many years’ residual deformations.

The Caribbean and Farallon Plates Connected: Constraints From Stratigraphy and Paleomagnetism of the Nicoya Peninsula, Costa Rica

AbstractPlate kinematic reconstructions play an essential role in our understanding of global geodynamics, but become increasingly difficult to constrain back in geological time due to the subduction of oceanic lithosphere. Here, we attempt to kinematically reconstruct the Cretaceous and older plate tectonic history of the Caribbean Plate within the Mesozoic Panthalassa (paleo‐Pacific) Ocean. To this end, we present new paleomagnetic data from Jurassic and Cretaceous oceanic sedimentary and volcanic Large Igneous Province‐related rocks of the Nicoya Peninsula and Murciélago Islands of northwestern Costa Rica. We use these data, in combination with constraints from marine magnetic anomalies to infer the age of the lithospheric basement, seismic tomography to locate deep‐mantle plume generation zones, and general kinematic feasibility, to test different reconstruction scenarios connecting the Caribbean Plate to the Farallon Plate as restored from Pacific spreading records. Our resulting reconstruction implies that the western Caribbean subduction zone initiated around 100 Ma, in an intraoceanic setting, breaking up oceanic lithosphere of at least 70 Myr old.

The SAMI Galaxy Survey: mass–kinematics scaling relations

ABSTRACT We use data from the Sydney-AAO Multi-object Integral-field spectroscopy (SAMI) Galaxy Survey to study the dynamical scaling relation between galaxy stellar mass M∗ and the general kinematic parameter $S_K = \sqrt{K V_{\rm rot}^2 + \sigma ^2}$ that combines rotation velocity Vrot and velocity dispersion σ. We show that the log M∗ – log SK relation: (1) is linear above limits set by properties of the samples and observations; (2) has slightly different slope when derived from stellar or gas kinematic measurements; (3) applies to both early-type and late-type galaxies and has smaller scatter than either the Tully–Fisher relation (log M∗ − log Vrot) for late types or the Faber–Jackson relation (log M∗ − log σ) for early types; and (4) has scatter that is only weakly sensitive to the value of K, with minimum scatter for K in the range 0.4 and 0.7. We compare SK to the aperture second moment (the ‘aperture velocity dispersion’) measured from the integrated spectrum within a 3-arcsecond radius aperture ($\sigma _{3^{\prime \prime }}$). We find that while SK and $\sigma _{3^{\prime \prime }}$ are in general tightly correlated, the log M∗ − log SK relation has less scatter than the $\log M_* - \log \sigma _{3^{\prime \prime }}$ relation.

Control of the Multi-Legged Robots on Planar, Unstable and Vibrating Ground

In this paper, we developed and investigated numerically a general kinematic model of a multi-legged hybrid robot equipped with a crab-like and/or mammal-like legs. To drive the robot’s limbs, a novel generator of gait was employed and tested. The simulation model developed in Mathematica is suitable for virtual study and visualization of the locomotion process. In contrast to our previous studies, in this paper we focused only on precise control the position of the robot during walking in different directions. We are able to simultaneous control all six spatial degrees-of-freedom of the robot’s body (three deviations and three rotations along and around three different axes, respectively), as well as all robot’s legs. As a result, the investigated robot can be considered and used as a fully controlled walking Stewart platform. What is more, the used algorithm can also be successfully employed to coordination and control all limbs of the robot on unstable or vibrating ground. As an example, the control algorithm can be used to stabilize spatial position of the robot when the supporting ground becomes vibrating or unstable, and it will keep the robot stable and prevent it from falling over. Since the recent versions of Mathematica allows to communicate with different microcontrollers such as Arduino Uno or Raspberry Pi, the developed simulation algorithms can be relatively simply adopted to control real constructions of different multi-legged robots.

Electromagnetic induction in a conducting D″ layer --- I: Effects of boundary charge accumulation and the boundary conditions

In response to the primary electric field originated by the fluid-core-dynamo, electric charges accumulate at the boundaries of a solid conducting D″ layer due to the poor circuitry conditions until the irrotational primary electric field is neutralized. The neutralization undoes the internal induction excited by the primary electric field and, as a result, eliminates the secondary toroidal magnetic field inside the D″. The primary magnetic field generated by the fluid-core-dynamo gives rise to a sustainable secondary poloidal magnetic field inside the conducting D″ layer. We introduce the general kinematic boundary conditions that are valid with different induction processes and parameter jumps across the core mantle boundary. We find by dimensional analysis that the strength of the secondary poloidal magnetic field is much weaker, by a factor of ∼10−2, than the irrotational primary. These findings indicate that the D″ is in effect an insulator for the geodynamo regardless of its material composition. Any mechanism for the core-mantle magnetic coupling should take this fact into consideration.

Something about a Railbound Forging Manipulator

Heavy payload forging manipulators are mainly characterized by large load output and large capacitive load input. The relationships between outputs and inputs have greatly influenced the control and reliability. Forging manipulators have become more prevalent in the industry today. They are used to manipulate objects to be forged. The most common forging manipulators are moving on a railway to have greater precision and stability. They have been called the rail-bound forging manipulators. In this paper, one presents the general aspects of a rail-bound forging manipulator, like geometry, structure, general kinematics and forces of the main mechanism from such manipulator. The kinematic scheme shows a typical forging manipulator, with the basic motions in operation process: Walking, the motion of the tong and buffering. The lifting mechanism consists of several parts including linkages, hydraulic drives and motion pairs. An idea of establishing the incidence relationship between output characteristics and actuator inputs is proposed. Self-forging systems have the ability to achieve an open, fast, direct forging of products that are often heavy and heavy but also bulky. Open forging productivity is generally very high, it is determined not only by the capacity of forging press but obviously dynamic handling by forging manipulator. The most prominent and qualitative forging machines are the DANGO and DIENENTHAL series, equipped with high dynamic devices and specially designed to operate on heavy forging presses. They ensure the reliability and repeatability of all forging cycles. Even a modernization of existing forging machines with D&D machines will improve the capacity and quality of these facilities. D&D handlers allow to forge nearly clean shapes and guarantee superior surface qualities, thus saving energy, improving production and saving costs during the machining of parts. Savings due to shorter process times and reduction of reheating cycles result in shorter recovery time.

Master integrals of a planar double-box family for top-quark pair production

We calculate analytically the master integrals of a planar double-box family for top-quark pair production using the method of differential equations. With a proper choice of the bases, the differential equations can be transformed to the d-log form. The square roots of the kinematic variables in the differential equations can be rationalized by defining two dimensionless variables. We find that all the boundary conditions can be fully fixed either by simple integrals or regularity conditions at some special kinematic points. The analytic results for thirty-three master integrals at general kinematics are all expressed in terms of multiple polylogarithms up to transcendental weight four.

A Paradigm for Path Following Control of a Ribbon-Fin Propelled Biomimetic Underwater Vehicle

This paper addresses the problem of path following for biomimetic underwater vehicles (BUVs) propelled by undulatory ribbon-fins. First, the general kinematics and dynamics models of underwater vehicles are presented, followed by a fuzzy logic model for dealing with a nonlinear relationship between the propulsive force/torque and the control parameters of the undulatory fins of the BUV. Then the path following problem of the BUV is formulated. A path following control paradigm integrating the line-of-sight guidance system with backstepping (BP) technique is proposed to maneuver the BUV to follow a predefined parameterized curve without time constraints. The stability of the BP controller is analyzed and guaranteed by Lyapunov stability theory. Finally, simulations and experimental results illustrate the performance of the proposed path following control paradigm.

Probing the tensor structure of lattice three-gluon vertex in Landau gauge

In this paper we test an approximate method that is often used in lattice studies of the Landau gauge three-gluon vertex. The approximation consists in describing the lattice correlator with tensor bases from the continuum theory. With the help of vertex reconstruction, we show that this "continuum" approach may lead, for general kinematics, to significant errors in vertex tensor representations. Such errors are highly unwelcome, as they can lead to wrong quantitative estimates for vertex form factors and related quantities of interest, like the three-gluon running coupling. As a possible solution, we demonstrate numerically and analytically that there exist special kinematic configurations for which the vertex tensor structures can be described exactly on the lattice. For these kinematics, the dimensionless tensor elements are equal to the continuum ones, regardless of the details of the lattice implementation. We ran our simulations for an $SU(2)$ gauge theory in two and three spacetime dimensions, with Wilson and $\mathcal{O}(a^2)$ tree-level improved gauge actions. Our results and conclusions can be straightforwardly generalised to higher dimensions and, with some precautions, to other lattice correlators, like the ghost-gluon, quark-gluon and four-gluon vertices.

Something about a Railbound Forging Manipulator

Heavy payload forging manipulators are mainly characterized by large load output and large capacitive load input. The relationships between outputs and inputs have greatly influenced the control and reliability. Forging manipulators have become more prevalent in the industry today. They are used to manipulate objects to be forged. The most common forging manipulators are moving on a railway to have greater precision and stability. They have been called the rail-bound forging manipulators. In this paper, one presents the general aspects of a rail-bound forging manipulator, like geometry, structure, general kinematics and forces of the main mechanism from such manipulator. The kinematic scheme shows a typical forging manipulator, with the basic motions in operation process: Walking, the motion of the tong and buffering. The lifting mechanism consists of several parts including linkages, hydraulic drives and motion pairs. An idea of establishing the incidence relationship between output characteristics and actuator inputs is proposed. Self-forging systems have the ability to achieve an open, fast, direct forging of products that are often heavy and heavy but also bulky. Open forging productivity is generally very high, it is determined not only by the capacity of forging press but obviously dynamic handling by forging manipulator. The most prominent and qualitative forging machines are the DANGO and DIENENTHAL series, equipped with high dynamic devices and specially designed to operate on heavy forging presses. They ensure the reliability and repeatability of all forging cycles. Even a modernization of existing forging machines with D&D machines will improve the capacity and quality of these facilities. D&D handlers allow to forge nearly clean shapes and guarantee superior surface qualities, thus saving energy, improving production and saving costs during the machining of parts. Savings due to shorter process times and reduction of reheating cycles result in shorter recovery time.

Probabilistic Kinematic Model of a Robotic Catheter for 3D Position Control.

Continuum robots offer compliant and dexterous operations, which are suitable to be used in unstructured environments. Tendon-driven catheters, owing to their continuum structure, are applied in minimal invasive surgeries such as intracardiac interventions. However, due to the intrinsic nonlinearities and external disturbances, it is still a challenging task to accurately steer the catheter tip to the desired 3D positions. In this article, we proposed a new probabilistic kinematic model and a model-based three-dimensional position control scheme for a tendon-driven cardiac catheter. A dynamic Gaussian-based probabilistic model is developed to learn a mapping from the catheter states to the control actions. Based on the probabilistic model, a closed-loop position control is developed, in which the catheter is driven by a newly designed catheter driver system and tracked by a multiple near-infrared camera system. The proposed catheter framework is evaluated by the 3D trajectory tracking experiments both in a real 3D open space and in a minimum-energy-based simulator. The proposed control framework approximates the general kinematic by a combination of a catheter translation model and a distal workspace model, which provides the ability of automatically positioning the catheter tip in 3D and improving the accuracy by compensating the learned nonlinear effects.

Nucleon resonances in Compton scattering

We calculate the nucleon resonance contributions to nucleon Compton scattering, including all states with J^P = 1/2^{+-} and J^P = 3/2^{+-} where experimental data for their electromagnetic transition form factors exist. To this end, we construct a tensor basis for the Compton scattering amplitude based on electromagnetic gauge invariance, crossing symmetry and analyticity. The corresponding Compton form factors provide a Lorentz-invariant description of the process in general kinematics, which reduces to the static and generalized polarizabilities in the appropriate kinematic limits. We derive the general forms of the offshell nucleon-to-resonance transition vertices that implement electromagnetic and spin-3/2 gauge invariance, which automatically also defines onshell transition form factors that are free of kinematic constraints. We provide simple fits for those form factors, which we use to analyze the resulting Compton form factors and extract their contributions to the nucleon's polarizabilities. Apart from the Delta(1232), the resonance contributions to the scalar and spin polarizabilites are very small, although the N(1520) could play a role for the proton's magnetic polarizability.

Kinematical, Structural and Mechanical Adaptations to Desiccation in Poikilohydric Ramonda myconi (Gesneriaceae).

Resurrection plants have fascinated scientists since centuries as they can fully recover from cellular water contents below 10%, concomitantly showing remarkable leaf folding motions. While physiological adaptations have been meticulously investigated, the understanding of structural and mechanical adaptations of this phenomenon is scarce. Using imaging and bending techniques during dehydration-rehydration experiments, morphological, anatomical, and biomechanical properties of desiccation-tolerant Ramonda myconi are examined, and selected structural adaptations are compared to those of homoiohydrous Monophyllaea horsfieldii (both Gesneriaceae). At low water availability, intact and cut-off R. myconi leaves undergo considerable morphological alterations, which are fully and repeatedly reversible upon rehydration. Furthermore, their petioles show a triphasic mechanical behavior having a turgor-based structural stability at high (Phase 1), a flexible mechanically state at intermediate (Phase 2) and a material-based stability at low water contents (Phase 3). Lastly, manipulation experiments with cut-off plant parts revealed that both the shape alterations of individual structures, as well as, the general leaf kinematics largely rely on passive swelling and shrinking processes. Taken together, R. myconi possesses structural and mechanical adaptations to desiccation (in addition to physiological adaptations), which may mainly be passively driven by its water status influenced by the water fluctuations in its surroundings.