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Many advances have been seen in adaptive structure technology during 1999. Among the successful adaptive systems demonstrations taking place were NASA-Langley's control of turbulent boundary layer noise on large panels in the AEDC wind tunnel and the development of a mission-adaptive aircraft engine inlet and a quieter marine propulsor by General Dynamics, Boeing and Penn State researchers.

The state of adaptive structures used in the aerospace industry advanced steadily in 1998. Studies on adaptive structures centered on their stability, safety and practical applications. Various smart materials were developed using different microfabrication techniques such as piezoceramic and stereolithography processing. Some of the companies and organizations which made significant progress in the area were the University of Maryland, Northrop Grumman, JPL, Hood and Honeywell.

Examines trends in piezoelectric actuation architectures. Forms of piezoelectric materials; Motion of piezoelectric material; Concept of bender actuators.

Short-bowel syndrome (SBS) is a rare, potentially lethal medical condition where the small intestine is far shorter than required for proper nutrient absorption. Current treatment, including nutritional, hormone-based, and surgical modification, have limited success resulting in 30% to 50% mortality rates. Recent advances in mechanotransduction, stressing the bowel to induce growth, show great promise; but for successful clinical use, more sophisticated devices that can be implanted are required. This paper presents two novel devices that are capable of the long-term gentle stressing. A prototype of each device was designed to fit inside a short section of bowel and slowly extend, allowing the bowel section to grow approximately double its initial length. The first device achieves this through a dual concentric hydraulic piston that generated almost 2-fold growth of a pig small intestine. For a fully implantable extender, a second device was developed based upon a shape memory alloy actuated linear ratchet. The proof-of-concept prototype demonstrated significant force generation and almost double extension when tested on the benchtop and inside an ex-vivo section of pig bowel. This work provides the first steps in the development of an implantable extender for treatment of SBS.