Method for Constructing Periodic Solutions of a Controlled Dynamic System with a Cylindrical Phase Space

Journal of Computer and Systems Sciences International - We consider a controlled mechanical system with one degree of freedom described by an angular coordinate. The system is under the action of...     

On wind turbine blade design optimization

A wind turbine with a horizontal rotation axis is considered in the stationary airflow. A problem of choosing the law of change of the setting angle of the cross section of the wind turbine blade and the value of the angular speed so that the wind energy utilization coefficient is maximal is discussed. Maximization of the respective functional is considered as a variational problem with a priori unknown parameter. Once it is solved numerically or analytically, the optimal value of this parameter is determined, with the sought variables given by rather simple formulas. The results are analyzed on a qualitative level. In particular, the setting angle is found to change monotonically along the blade, which is confirmed by practical wind turbine design. Examples of using the proposed approach to wind turbine blade design are considered.     

Method for Forming Autorotations in Controllable Mechanical System with Two Degrees of Freedom

Journal of Computer and Systems Sciences International - An autonomous mechanical system with two rotational degrees of freedom, undergoing the action of conservative and nonconservative forces, is...     

Plane-Parallel Motion of a Snake Robot in the Presence of Anisotropic Dry Friction and a Single Control Input

Journal of Computer and Systems Sciences International - A snake robot moving along a rough plane is considered. Anisotropic dry friction acts at the points of contact with the support. The link...     

DNA G-Quadruplexes Contribute to CTCF Recruitment

G-quadruplex (G4) sites in the human genome frequently colocalize with CCCTC-binding factor (CTCF)-bound sites in CpG islands (CGIs). We aimed to clarify the role of G4s in CTCF positioning. Molecular modeling data suggested direct interactions, so we performed in vitro binding assays with quadruplex-forming sequences from CGIs in the human genome. G4s bound CTCF with Kd values similar to that of the control duplex, while respective i-motifs exhibited no affinity for CTCF. Using ChIP-qPCR assays, we showed that G4-stabilizing ligands enhance CTCF occupancy at a G4-prone site in STAT3 gene. In view of the reportedly increased CTCF affinity for hypomethylated DNA, we next questioned whether G4s also facilitate CTCF recruitment to CGIs via protecting CpG sites from methylation. Bioinformatics analysis of previously published data argued against such a possibility. Finally, we questioned whether G4s facilitate CTCF recruitment by affecting chromatin structure. We showed that three architectural chromatin proteins of the high mobility group colocalize with G4s in the genome and recognize parallel-stranded or mixed-topology G4s in vitro. One of such proteins, HMGN3, contributes to the association between G4s and CTCF according to our bioinformatics analysis. These findings support both direct and indirect roles of G4s in CTCF recruitment.     

Controlling the Operating Modes of a Hinged Wind Turbine

Journal of Computer and Systems Sciences International - We consider a small device for converting the medium’s flow energy, which is designed based on the use of a crank mechanism. A blade...     

Wind Turbine of the Savonius–Magnus Type with Conical Blades: Dynamics and Control

Journal of Computer and Systems Sciences International - We consider a mathematical model of a horizontal-axis wind-energy unit in which Savonius rotors are used instead of classical blades. The...     

Three-Link Mechanism as a Model of a Person on a Swing

Journal of Computer and Systems Sciences International - We model movements of a person swinging on a swing. We consider a flat three-link hinged mechanism as the main mechanical model of the...     

Darrieus-Magnus Type Wind Turbine: Dynamics and Control

Journal of Computer and Systems Sciences International - When the Darrieus rotor rotates, a force is generated that is akin to the Magnus force: perpendicular to the oncoming flow velocity. In this...     

Intensity and Efficiency of Luminescence in U(IV) Oxidation with Xenon Difluoride,as Influenced by the Solution Acidity

Unusually strong influence of the solution acidity on the chemiluminescence intensity (I_cl) in U(IV) oxidation with xenon difluoride was found. Although the intensity of uranyl photoluminescence (I_fl) increases by a factor of 3 with increasing HClO₄ concentration from 0.5 to 2 M, under these conditions the maximal I_cl in U(IV) oxidation with XeF₂ decreases by a factor of 8 and the quantum yield of CL (η_cl) decreases by a factor of 4.6. This strong influence of pH of the solution on I_cl and η_cl is likely due to deceleration of hydrolysis of U(V) intermediate to form uranyl(V) ion.