No abstract

Until now, little research attention in the area of Augmented Reality (AR) has been paid to the cognitive benefits engendered by this emerging technology. AR, the synthesis of computer images and text in the real world (Azuma, 1997), affords a supplement to normal information acquisition that has yet to be fully explored and exploited. AR achieves a more smooth and seamless interface by complementing human cognitive networks, and aiding information integration through multi-modal sensory elaboration, by utilizing visual, verbal, proprioceptive, and tactile memory while the user is performing real world tasks. AR also incorporates visuo-spatial ability, which involves the representations of spatial information in memory. The use of this type of information is an extremely powerful form of elaboration.This study examined four learning paradigms: print (printed material) mode, observe (video tape) mode, interact (text annotations activated by mouse interaction) mode, and select (AR) mode. The results of the experiment indicated that the select (AR) mode resulted in better learning and recall when compared to the other 3 conventional modes of learning. Implications for training and curriculum design are discussed.

Liquid sloshing within spacecraft propellant tanks causes rapid energy dissipation at resonant modes, which can result in attitude destabilization of the vehicle. Identifying resonant slosh modes currently requires experimental testing and mechanical pendulum analogs to characterize the slosh dynamics. Computational Fluid Dynamics (CFD) techniques have recently been validated as an effective tool for simulating fuel slosh within free-surface propellant tanks. Propellant tanks often incorporate an internal flexible diaphragm to separate ullage and propellant which increases modeling complexity. A coupled fluid-structure CFD model is required to capture the damping effects of a flexible diaphragm on the propellant. ANSYS multidisciplinary engineering software employs a coupled solver for analyzing two-way Fluid Structure Interaction (FSI) cases such as the diaphragm propellant tank system. Slosh models generated by ANSYS software are validated by experimental lateral slosh test results. Accurate data correlation would produce an innovative technique for modeling fuel slosh within diaphragm tanks and provide an accurate and efficient tool for identifying resonant modes and the slosh dynamic response.

No abstract

The flexibility of welded joints is an important issue in structural analysis and design of car bodies. Two three-dimensional, design-oriented models (uncoupled and coupled) are developed to represent the complaint behavior of multibranch flexible joints. The uncoupled model consists of torsional springs restraining the relative rotation of the joint branches in the three planes, while all branches are assumed to be rigidly connected in translation. Coupling between motions in different planes is neglected. The coupled model accounts for such coupling. A statistical system identification method is proposed for inferring the model parameters from the static response of the structure. The method is demonstrated by applying it to a simple cube frame structure and a car body. Finally, the two models are compared in terms of their ability to predict static response. NomenclatureComplex = strain energy of complex model E m = error vector Simple = strain energy of simple model F = force vector F R = reduced force vector K = stiffness matrix Kj = joint stiffness matrix overall = overall stiffness matrix K R = reduced stiffness matrix of structure without the joint KU = stiffness matrix of unconstrained joint kij = elements of joint stiffness matrix kj = joint stiffness parameter vector L f = length of force vector U = displacement vector U A = vector of actual displacements U E = strain energy stored by the springs U m = measured displacement vector u = rotation vector V m = covariance matrix of measurement errors X m = matrix formed from the measured displacements 6 iy = rotational degrees of freedom at joint