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This paper describes a graphical representation technique for models in VHDL. The graphical representation is an extension of the Process Model Graph described in [1]. The Process Model Graph has representations for concurrent processes and signals. The representation described here, referred to as the Modified Process Model Graph, adds several new constructs to handle more features of VHDL. These new constructs include: variables inside process blocks, a visual notation for sensitivity lists, and a clear visual indication of the interface to an object. A software tool, called VHDLCad* (c)* * , has been developed that uses produces VHDL source code interactively from the graphical representation. The tool allows the user to use pre-defined modules, or create new modules and place them in the library. With the benefit of a graphical representation, a menu-driven system and re-usable code, VHDLCad can improve the productivity of VHDL modelers. *VHDLCad is a trademark of David G. Burnette. **Copyright 1988 by David G. Burnette. All rights reserved / Master of Science

The objective of this study was to develop a two-dimensional computer model for the simulation of the resin transfer molding/resin film infusion processing of advanced composite materials. This computer simulation model is designed to provide aircraft structure and tool designers with a method of predicting the infiltration and curing behavior of a composite material component. For a given specified cure cycle, the computer model can be used to calculate the resin infiltration, resin viscosity, resin advancement, heat transfer within the component/tool assembly during processing and preform compaction. Formulations of the resin flow problem are given using the finite element/control volume technique based on Darcy's Law of flow through porous media. This technique allows for the efficient numerical calculation of the advancing resin front within the preform materials. The heat transfer in the fabric preform and tooling is analyzed using a transient finite element method which included the effects of convection on the tooling surfaces. Compaction behavior of the tooling assembly is analyzed using a simplified isotropic form of the plane elasticity equations. All of these solutions were coupled together in a quasisteady state non-linear fashion inside the computer code. / Master of Science

Emergency ejection of an air crew member from military aircraft in flight places dangerously large vertical acceleration forces on the body of the member. The additional mass on the head due to Night Vision Goggles and Helmet Mounted Displays increases the vulnerability of the head/neck system to injury. To eliminate the need for human testing, computer simulations of biodynamic head and neck system response to large vertical accelerations have been produced. A head/neck characteristic was developed which included the rotation and axial deformation properties of the cervical spine. The characteristic consisted of three rigid segments representing the head, neck, and upper torso, a ball-and socket joint representing the head/neck articulation, and a slip joint representing the neck/torso articulation. The model was exercised using the Articulated Total Body Model developed by Calspan Corporation and Armstrong Laboratory. The model parameters were determined using human vertical deceleration test data acquired at Armstrong Laboratory. Simulations of human biodynamic response to ejection acceleration show the proposed head/neck characteristic to produce improved correlation with human biodynamic response to 10 Gz acceleration when compared to previous rigid body models of the human head/neck system. / Master of Science