Input-Output Analysis and Control Applied to Spatially Developing Shear Flows

Input-Output Analysis and Control Design Applied to a Linear Model of Spatially Developing Flows

Applied Mechanics Reviews ◽

10.1115/1.3077635 ◽

2009 ◽

Vol 62 (2) ◽

Cited By ~ 82

Author(s):

S. Bagheri ◽

D. S. Henningson ◽

J. Hœpffner ◽

P. J. Schmid

Keyword(s):

Fluid Mechanics ◽

Model Reduction ◽

Landau Equation ◽

Control Design ◽

Input Output ◽

Output Analysis ◽

Ginzburg Landau ◽

Input Output Analysis ◽

Ginzburg Landau Equation ◽

And Control

This review presents a framework for the input-output analysis, model reduction, and control design for fluid dynamical systems using examples applied to the linear complex Ginzburg–Landau equation. Major advances in hydrodynamics stability, such as global modes in spatially inhomogeneous systems and transient growth of non-normal systems, are reviewed. Input-output analysis generalizes hydrodynamic stability analysis by considering a finite-time horizon over which energy amplification, driven by a specific input (disturbances/actuator) and measured at a specific output (sensor), is observed. In the control design the loop is closed between the output and the input through a feedback gain. Model reduction approximates the system with a low-order model, making modern control design computationally tractable for systems of large dimensions. Methods from control theory are reviewed and applied to the Ginzburg–Landau equation in a manner that is readily generalized to fluid mechanics problems, thus giving a fluid mechanics audience an accessible introduction to the subject.

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Planning with Semi-input-output Method with Empirical Application to Nigeria. By Arie Kuyvenhoven. Leiden: Martinus Nijhoff Social Sciences Division. 1978. xi + 266 pp.

The Pakistan Development Review ◽

10.30541/v19i3pp.247-249 ◽

1980 ◽

Vol 19 (3) ◽

pp. 247-249

Author(s):

A. R. Kemal

Keyword(s):

Social Sciences ◽

Developing Countries ◽

Final Demand ◽

The Other ◽

Production Structure ◽

Input Output ◽

Output Analysis ◽

Input Output Analysis ◽

Comparative Cost ◽

Planning Models

Input -output analysis is being widely used in developing countries for planning purposes. For a given level of final demand, input-output analysis allows us to project the required level of gross output to ensure consistency of plan. These projections are made on the assumption that the existing production structure is optimal and it implies that an increase in demand will be met through the expansion of domestic output even when it can be satisfied through an increase in imports. On the other hand, according to the semi-input-output method, we do not have to increase the output of international sectors in order to meet the increase in demand because the level and composition of these activities should be determined by comparative- cost considerations. These are the only national sectors in which output must increase in order to avoid shortage. The semi-input -output method has been such a useful and important contribution, yet, regrettably, its influence on the planning models had been rather limited.

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