SVD-Krylov based Sparsity-preserving Techniques for Riccati-based Feedback Stabilization of Unstable Power System Models

We propose an efficient sparsity-preserving reduced-order modelling approach for index-1 descriptor systems extracted from large-scale power system models through two-sided projection techniques. The projectors are configured by utilizing Gramian based singular value decomposition (SVD) and Krylov subspace-based reduced-order modelling. The left projector is attained from the observability Gramian of the system by the low-rank alternating direction implicit (LR-ADI) technique and the right projector is attained by the iterative rational Krylov algorithm (IRKA). The classical LR-ADI technique is not suitable for solving Riccati equations and it demands high computation time for convergence. Besides, in most of the cases, reduced-order models achieved by the basic IRKA are not stable and the Riccati equations connected to them have no finite solution. Moreover, the conventional LR-ADI and IRKA approach not preserves the sparse form of the index-1 descriptor systems, which is an essential requirement for feasible simulations. To overcome those drawbacks, the fitting of LR-ADI and IRKA based projectors from left and right sides, respectively, desired reduced-order systems attained. So that, finite solution of low-rank Riccati equations, and corresponding feedback matrix can be executed. Using the mechanism of inverse projection, the Riccati-based optimal feedback matrix can be computed to stabilize the unstable power system models. The proposed approach will maintain minimized ℌ2 -norm of the error system for reduced-order models of the target models.

Geometry and Kinematics of Cylindrical Waterbomb Tessellation

Folded surfaces of origami tessellations have attracted much attention because they sometimes exhibit non-trivial behaviors. It is known that cylindrical folded surfaces of waterbomb tessellation called waterbomb tube can transform into wave-like surfaces, which is a unique phenomenon not observed on other tessellations. However, the theoretical reason why wave-like surfaces arise has been unclear. In this paper, we provide a kinematic model of waterbomb tube by parameterizing the geometry of a module of waterbomb tessellation and derive a recurrence relation between the modules. Through the visualization of the configurations of waterbomb tubes under the proposed kinematic model, we classify solutions into three classes: cylinder solution, wave-like solution, and finite solution. Furthermore, we give proof of the existence of a wave-like solution around one of the cylinder solutions by applying the knowledge of the discrete dynamical system to the recurrence relation.

Research on a Numerical Calculation for Ball Bearings Based on a Finite Initial Value Search Method

To address the disadvantages of the traditional solution method of the quasistatic ball bearing model, which requires the acquisition of the initial value with experience, this paper proposes a new method for a finite initial value optimization to solve the quasistatic ball bearing model. A bilevel solution model is established; the first layer is the initial value strategy model, and the second layer is the numerical optimization model. The Levenberg–Marquardt algorithm and the Armijo algorithm are adopted to solve the model. The correctness of the new method is proved by a case study of calculating a parameter of the bearing compared with the traditional method. The experiment results show that the proposed method can realize the fast and finite solution of the quasistatic ball bearing model. Additionally, the new method can be extended to the calculation of the double-decker ball bearings. It provides a reasonable and effective way for the exploration of the initial value problem of the solution of a quasistatic ball bearing model.

State of the art - optimization techniques in cloud environment

A Cloud is a network of a shared pool of configurable and computing resources providing efficient, on-demand pay-as-per-use access. Its main objectives being: Scalability, High availability of resources and to reduce the overhead incurred. Scheduling is the method of determining the order by which the jobs have to be executed. It determines the various tasks that are to be executed in parallel and the efficient resource to carry out the tasks. Load balancing is the method of balancing the load across various resources by fixing a threshold and migrating the tasks to the under loaded resources based on the threshold. Optimization techniques are used to find a finite solution for scheduling of tasks although not optimal. Various optimization techniques are employed based on Cost, CPU utilization and to balance the load. This paper deals with the importance of optimization, the various metrics and constraints associated. A literature survey on the various optimization techniques is also analyzed based on the attributes of the tasks.

Effective action of in Krein space quantization

The appearance of divergence creates computational issues in the process of calculating the one-loop effective action of [Formula: see text] in quantum field theory. In this paper, it is demonstrated that using Krein space quantization with Ford’s method of fluctuated metrics, divergence can be removed and that without using any traditional regularization method, it is possible to arrive at a finite solution for the effective action.

Design of Robust and Non-Fragile Kalman Filter with Polytopic Uncertainties: PLMI Approach

In this paper, we describe the synthesis of robust and non-fragile Kalman filter design for a class of uncertain linear system with polytopic uncertainties and filter gain variations. The sufficient condition of filter existence, the design method of robust non-fragile filter, and the measure of non-fragility in filter are presented via LMIs(Linear Matrix Inequality) technique. And the obtained sufficient condition can be represented as PLMIs(Parameterized Linear Matrix Inequalities) that is, coefficients of LMIs are functions of a parameter confined to a compact set. Since PLMIs generate infinite LMIs, we use relaxation technique, find a finite solution for robust non-fragile filter, and show that the resulting filter guarantees the asymptotic stability with parameter uncertainties and filter fragility. Finally, a numerical example is shown to validate the proposed design method.

Formation Mechanism of Huge Coastal Polynyas and Its Application to Okhotsk Northwestern Polynya

This paper investigates the formation mechanism of broad coastal polynyas beyond 100 km in offshore width. It is known that two regimes for wind-driven polynya opening exist: one is a convergent regime at the polynya edge in which inner frazil ice catches up with outer consolidated ice, whereas the other is a divergent regime in which the consolidated ice drifts offshore faster than the frazil ice at the edge. In this study, the authors focus on the latter, divergent polynya-edge regime. Because in the divergent regime the polynya possibly evolves without bound, they consider a thermal growth for inner frazil ice to find a finite solution of offshore width. Then, the authors investigate responses of the polynya opening for various wind angles ϕ from the offshore direction from the viewpoint of the polynya-edge regimes. At first, the authors estimate the deviation angle and wind factor for the frazil and consolidated ice based on each momentum balance, because sea ice motion driven by wind varies depending on the ice thickness due to relative effect of the Coriolis force. It was found that, when the surface wind deviates leftward about 10° or greater from offshore, the divergent regime at the polynya edge generates a great polynya evolution. Otherwise, the convergent regime takes place yielding small offshore extent. These theoretical results were verified for the Okhotsk northwestern polynya using thin-ice-thickness data derived from Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) and the Japanese 25-year Reanalysis (JRA-25) surface wind. The data show that the polynya development distinctively changes at ϕ ∼ 0°, and the largest width is shown in the leftward wind angle of ϕ = 0°–30°. This clear relationship between the surface wind angle and the offshore extent of polynya nicely supports the theory.