Shape memory polymers (SMPs) have been candidate materials for morphing applications. However, the SMPs have not been fully tested to work in relevant environments required for Air Force missions. In this study, an epoxy-based SMP was separately exposed to moisture, lubricating oil and UV radiation, which are simulated service environments designed to be reflective of anticipated performance requirements. The thermomechanical properties and shape memory effects were studied by using novel high-temperature nanoindentation technique. Results show that environmental conditions have affected the glass transition temperature and mechanical properties of the SMPs. In most cases, the conditioned SMPs exhibited higher elastic moduli than the unconditioned SMP. The shape recovery ability of the SMP was assessed by creating an indent and then observing the corresponding recovery according to the standard shape memory cycle. It was found that the deformation was mostly recovered for both conditioned and unconditioned SMP samples on heating the material above its glass transition temperature.

This paper was presented at CJK-OSM 7, 18–21 June 2012, Huangshan, China.

This report describes investigations of the NE213-detector and the possibility to utilize pulse shape analysis to separate neutrons and gammas in a mixed emission field. Neutron fluxes are often contaminated with gammas, to which the detectors are sensitive. Sorting out the unwanted gamma pulses from the interesting neutrons is therefore crucial in many situations, for instance in fusion reactor diagnostics, such as for neutron cameras. This can be done based on pulse shapes, which differ for gammas and neutrons interacting in the NE213-detector. By analyzing the pulse shapes from a digital transient recorder, neutrons can be distinguished from gammas. An experiment with a Cf-252 neutron source was set up and provided data. The separation algorithm was based on charge comparison and gave good results. Furthermore the results of the pulse shape analysis were verified by TOF-measurements. The lowest permissible energy for a reasonable separation was found to be around 0.5 MeV. Some conclusions on the limitations of the equipment were also made.

This study is concerned with the design and development of a novel wing for UAVs that morphs seamlessly without the use of complex hydraulics, servo motors and controllers. The selected novel design is characterized by a high degree of flight adaptability and improved performance with a limited added weight. These characteristics were attained through the use of shape memory actuators in an antagonistic fashion. Unlike compliant actuators, the antagonistic setup requires the thermal energy to deform the wing but not to maintain its deformed shape. Structural analysis based upon safety factors specified by FAR23 standards and aerodynamic analysis using FLUENT were conducted on the novel design to validate its suitability as a viable wing for UAVs. In addition, thermal conditioning of the shape memory actuators was conducted using a specially designed programmable controller. This thesis does not concern itself with the design of a skin that accommodates the shape changes.

This study is concerned with the design and development of a novel wing for UAVs that morphs seamlessly without the use of complex hydraulics, servo motors and controllers. The selected novel design is characterized by a high degree of flight adaptability and improved performance with a limited added weight. These characteristics were attained through the use of shape memory actuators in an antagonistic fashion. Unlike compliant actuators, the antagonistic setup requires the thermal energy to deform the wing but not to maintain its deformed shape. Structural analysis based upon safety factors specified by FAR23 standards and aerodynamic analysis using FLUENT were conducted on the novel design to validate its suitability as a viable wing for UAVs. In addition, thermal conditioning of the shape memory actuators was conducted using a specially designed programmable controller. This thesis does not concern itself with the design of a skin that accommodates the shape changes.

The objective of this work is to characterize and understand structure- mechanical property relationships in (meth)acrylate networks. The networks are synthesized from mono-functional (meth)acrylates with systematically varying sidegroup structure and multi-functional crosslinkers with varying mole fraction and functionality. Fundamental trends are established between the network chemical structure, crosslink density, glass transition temperature, rubbery modulus, failure strain, and toughness. The glass transition temperature of the networks ranged from -29 to 112 °C, and the rubbery modulus ranged from 2.8 to 129.5 MPa. At low crosslink density (Er < 10 MPa) network chemistry has a profound effect on network toughness. At high crosslink densities (Er > 10 MPa), network chemistry has little influence on material toughness. The characteristic ratio of the mono-functional (meth)acrylates components is unable to predict trends in thermoset toughness as a function of chemical structure, as is accomplished for thermoplastics. The cohesive energy density is a better tool for prediction of network mechanical properties. Due to superior mechanical properties, networks with phenyl ring sidegroups are further investigated to understand the effect of phenyl ring distance on toughness. This work provides a fundamental basis for designing (meth)acrylate shape memory polymer networks with specific failure strain, toughness, glass transition temperature, and rubbery modulus.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 70).

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gall, Ken; Committee Chair: May, Gary S; Committee Member: Brand, Oliver; Committee Member: Degertekin, F Levent; Committee Member: Milor, Linda S. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 98-99). Also available via the Internet.

The question of how shape is represented is of central interest to understanding visual processing in cortex. While tuning properties of the cells in early part of the ventral visual stream, thought to be responsible for object recognition in the primate, are comparatively well understood, several different theories have been proposed regarding tuning in higher visual areas, such as V4. We used the model of object recognition in cortex presented by Riesenhuber and Poggio (1999), where more complex shape tuning in higher layers is the result of combining afferent inputs tuned to simpler features, and compared the tuning properties of model units in intermediate layers to those of V4 neurons from the literature. In particular, we investigated the issue of shape representation in visual area V1 and V4 using oriented bars and various types of gratings (polar, hyperbolic, and Cartesian), as used in several physiology experiments. Our computational model was able to reproduce several physiological findings, such as the broadening distribution of the orientation bandwidths and the emergence of a bias toward non-Cartesian stimuli. Interestingly, the simulation results suggest that some V4 neurons receive input from afferents with spatially separated receptive fields, leading to experimentally testable predictions. However, the simulations also show that the stimulus set of Cartesian and non-Cartesian gratings is not sufficiently complex to probe shape tuning in higher areas, necessitating the use of more complex stimulus sets.