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In this paper, the optimal location of a distributed network of actuators within a scissor wing mechanism is investigated. The analysis begins by developing a mechanical understanding of a single cell representation of the mechanism. This cell contains four linkages connected by pin joints, a single actuator, two springs to represent the bidirectional behavior of a flexible skin, and an external load. Equilibrium equations are developed using static analysis and the principle of virtual work equations. An objective function is developed to maximize the efficiency of the unit cell model. It is defined as useful work over input work. There are two constraints imposed on this problem. The first is placed on force transferred from the external source to the actuator. It should be less than the blocked actuator force. The other is to require the ratio of output displacement over input displacement, i.e., geometrical advantage (GA), of the cell to be larger than a prescribed value. Sequential quadratic programming is used to solve the optimization problem. This process suggests a systematic approach to identify an optimum location of an actuator and to avoid the selection of location by trial and error. Preliminary results show that optimum locations of an actuator can be selected out of feasible regions according to the requirements of the problem such as a higher GA, a higher efficiency, or a smaller transferred force from external force. Results include analysis of single and multiple cell wing structures and some experimental comparisons.

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The combined optimization of a compliant mechanism and a piezoelectric stack actuator for maximum energy conversion efficiency is considered. The analysis assumes all components to be free from dissipation and that the piezoelectric stack actuator is driven by an ideal sinusoidal voltage source.

Communities of all sizes are investing in minor league stadiums to attract or retain a minor league baseball team. The promise of economic development benefits is often put forward to justify these multimillion dollar investments. Local officials should be aware of the risks that accompany hosting professional sports teams and understand that minor league teams will not be economic growth engines. The decision to invest in a minor league stadium is a public policy decision and can be "worth it" if accompanied by a development logic. This article identifies three approaches that have been successful in making stadiums a community asset. Copyright 1998 by The Policy Studies Organization.