Optimization of 3-DoF Manipulators’ Parasitic Motion with the Instantaneous Restriction Space-Based Analytic Coupling Relation

This paper presents a velocity-level approach to optimizing the parasitic motion of 3-degrees of freedom (DoFs) parallel manipulators. To achieve this objective, we first systematically derive an analytical velocity-level parasitic motion equation as a primary step for the optimization. The paper utilizes an analytic structural constraint equation that describes the manipulator’s restriction space to formulate the parasitic motion equation via the task variable coupling relation. Then, the relevant geometric variables are identified from the analytic coupling equation. The Quasi-Newton method is used for the direction-specific minimization, i.e., optimizing either the x-axis or y-axis parasitic motion. The pattern-search algorithm is applied to optimize all parasitic terms from the workspace. The proposed approach equivalently describes the 3-PhRS, 3-PvRS, 3RPS manipulators. Moreover, other manipulators within a similar category can be equivalently expressed by the proposed method. Finally, the paper presents the resulting optimum configurations and numerical simulations to demonstrate the approach.

The superradiant stability of Kerr-Newman black holes

In this article, the superradiation stability of Kerr-Newman black holes is discussed by introducing the condition used in Kerr black holes y into them. Moreover, the motion equation of the minimal coupled scalar perturbation in a Kerr-Newman black hole is divided into angular and radial parts. We adopt the findings made by Erhart et al. on uncertainty principle in 2012, and discuss the bounds on y.

Exponential stability for a piezoelectric beam with a magnetic effect and past history

<p style='text-indent:20px;'>Solutions for systems consisting of coupled wave equations, one of them with past history, may present different behaviors due to the type of coupling. In this paper, the issue of exponential stability for a piezoelectric beam with magnetic effect and past history is analyzed. In the work is proved that the past history term acting on the longitudinal motion equation is sufficient to cause the exponential decay of the semigroup associated with the system, independent of any relation involving the model coefficients.</p>

Methods of Information Processing of Relative Motion in the Flying Groups of UAV

In this article, the author investigates information processing algorithms in order to determine the relative UAV motion parameters in a group flight and proposes an algorithm for estimating the leading UAV motion parameters from the results of relative motion measurements. Such researches are especially important nowadays in all the spheres where the drones are used and/or will be used. The author considers the problems of management of the UAV in the group flight, formulation of the problem for processing of the information in such the conditions. The article considers relative motion equation and the synthesis of information processing algorithms in the master-slave model of the flying group of UAV.

On kinetics of superconducting state destruction in a nonlinear coplanar waveguide based on a high-temperature superconductor film

Subject and Purpose. The mechanism of destruction of the S-state of a nonlinear high-temperature superconductor as part of a coplanar waveguide has not been properly elucidated as the effect of avalanche-type transition to a highly dissipative state, which was experimentally detected by the authors, takes place. The present work is concerned with the development of an appropriate approach describing kinetics of destruction of the S-state of a nonlinear high-temperature superconductor in a coplanar waveguide with allowances made for an inhomogeneous distribution of the microwave current in the superconducting film strip. Methods and Methodology. Use of I.B. and O.G. Vendiks’ reasoning [2] is made on kinetics of the destruction of the superconducting state of a wide film when a direct current governed by the time-dependent Ginzburg-Landau equation is applied. Keeping unchanged their idea as to the S–N boundary forming in the film strip with the boundary movement to the middle of the strip, the S–N boundary motion equation is obtained for a coplanar waveguide, proceeding in doing this from the motion equation of magnetic flux vortices under certain restrictions specified. Results. The time of S-state destruction has been numerically estimated: 1) for a wide superconducting film of YBa2Cu3O7–d composition, the destruction is by the direct current and 2) for a coplanar waveguide based on the same film, the destruction is by the microwave current. When the superconductivity is small (I / I c ³ 1), the destruction time values in both cases are close to each other within the order of magnitude. Conclusion. It is for the first time that the S-state destruction time in a coplanar waveguide has been expressed in terms of the microwave current distribution in the waveguide. It has been shown that this characteristic linearly depends on the ratio between the critical current and the microwave current amplitude in contrast to a quadratic dependence obtained for a superconducting strip with a direct current.