Ryosuke Morita

Flutter Analysis and Experiments of a Rectangular Sheet Supported by a Wire

This paper deals with a flutter analysis of a rectangular sheet supported by a wire in axial flow. In the flutter analysis, Doublet-point method based on the unsteady lifting surface theory is used to calculate the unsteady fluid force acting on the sheet surface. The equation of motion of the sheet supported the wire with tension is derived by using the finite element method. The flutter velocity and mode of the sheet are examined through the root locus of the flutter determinant of the system with changing the flow velocity. In this study, experiments are conducted and compared with the analytical results. The flutter velocity, its mode, and the local work by the fluid force acting on the sheet surface with changing tension of wire are determined. Moreover, the effects of boundary condition on flutter characteristic are determined. As the tension of the wire becomes higher, the flutter velocity and its frequency increase. Traveling-wave mode flutter occurs to the sheet when the flow velocity becomes higher. In the case of lower tension of the wire, the amplitude of the flutter mode at the upstream end is large. The local work done by the fluid force around the center of the sheet is positive, and that near the downstream end of the sheet is negative. Moreover, local work on the sheet surface and flutter mode for different boundary condition depend on dominant mode contribute to flutter mode.Copyright

Multiagent Consensus With Noisy Communication: Stopping Rules Based on Network Graphs

A stopping rule is presented for a multiagent consensus algorithm with noisy communication. A stochastic approximation method is employed and the relation between the closeness of the agreement and the number of iterations is established. A bound of the variation of the agents at the specific number of iterations is then derived with a probabilistic guarantee, which gives a rigorous stopping rule of the consensus algorithm with noisy communication. This stopping rule is given in terms of characteristic values of communication network graphs, which suggests a difference in transient behaviors by undirected and directed graphs. These theoretical results are demonstrated through numerical examples.

ODQLab: A graphical software tool to design dynamic quantizers for discrete-valued input control

This paper presents a software tool, entitled ODQLab, to design dynamic quantizers for discrete-valued input control. ODQLab is a Matlab-based graphical tool, which enables us to obtain and verify dynamic quantizers without the knowledge of any sophisticated design theory. In this paper, we introduce the software tool with the underlying theory. The effectiveness is demonstrated by a design example and the experimental evaluation.

An evaluation of equilibrium motor learning in the seated posture based on the CoP and the trunk motion

This paper aims at evaluating the progression of the motor learning in the balancing task in the seated posture. Our previous paper revealed that an equilibrium perception detecting the subjective upright was affected from a balancing task. To explain the process of this perceptual change, the behavioral evaluation of the motor learning task seems to be required. Here, we evaluated the behavior of the motor learning by the CoP movement and the mean trunk inclination. As a result, the former was categorized into two patterns based on the relative phase of the CoP against the controlled periodic seat movement. On the other hand, the latter was classified into three types with their mean and changing rate during the motor learning.

Performance analysis of feedback control systems with subtractive dither

Subtractive dither method is that artificial noise is added to the original signal before quantization and the same noise is subtracted from the quantized signal. In some sense, this mechanism is similar to symmetric-key algorithm of encrypted communication. In this paper, a subtractive dither method is applied into quantized feedback control systems and the performance of quantizers with subtractive dither is analyzed. A numerical simulation is also shown with comparing to a non-subtractive dither method and the advantage of subtractive dither is demonstrated.

Dynamic simulation of a wind farm incorporated with highly-resolved wind prediction data

This paper presents and discusses dynamic simulation of a wind farm incorporated with highly-resolved wind prediction data. The wind farm is comprised of twenty 3 MW direct drive synchronous generators arranged in two arrays and connected to an infinite bus representing the commercial grid. Each generator is equipped with a full-scale power converter and a pitch angle controller. The wind farm receives input data (wind speeds) from a weather simulation model called the Cloud Resolving Storm Simulator (CReSS) for the geographical locations of every wind turbine.

Multi-agent consensus with noisy communication via time averaging

A stochastic approximation with averaging is applied to a consensus algorithm for multi-agent systems and the convergence of the algorithm is analyzed. The consensus is considered with respect to the time average of the states of agents. For the fixed network structure and time-varying structure, the relation between the number of iterations of the algorithm and consensus accuracy is explicitly clarified. Finally a numerical example is shown and a presented theorem is demonstrated.

Randomized solution for robust optimal power flow

Robust optimal power flow problem is to find the optimal operating setting of a power system subject to some constraints based on power and voltage for any uncertain power generation. Since this problem is NP hard due to its nonconvexity, a computationally cheap randomized algorithm is presented. The algorithm is applied for the New England test system and its efficiency is demonstrated through numerical examples.