Neil R. Weston

Strategies for Integrating Models of Interdependent Subsystems of Complex System-Of-Systems Products

The Office of Naval Research has established a need for improved design and analysis methods for the next generation of naval surface combatants. The Aerospace Systems Design Laboratory (ASDL) has initiated the integrated reconfigurable intelligent systems project to address design issues associated with the future systems. A goal of this program is to define preliminary approaches for developing an integrated modeling and simulation environment for complex systems. Since such systems are heterogeneous, dynamical and interdependent we suggest that a system-of-systems multidisciplinary approach is most appropriate for investigating and executing solutions. An integration methodology employing innovative techniques and a framework of tools that can be used to couple disparate models and simulations is presented. Methods for validating the final product to justify the selected approach and demonstrate a proof of concept for the integrated model are also discussed

A conceptual design environment for technology selection and performance optimization for torpedoes

Presented at the 9th Multi-Disciplinary Analysis and Optimization Symposium in Atlanta, GA, September 4-6, 2002.

Advanced Design of Complex Systems Using the Collaborative Visualization Environment (CoVE)

Presented at the 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, January 10-13, 2005.

Modeling and simulation of integrated intelligent systems

Complex systems consist of a large number of entities with their independent local rules and goals, along with their interactions. The effect of these properties tends to produce complex behaviors that are required to be understood in order to analyze and design the systems. However, these behaviors are difficult to be predicted a priori, and can only be studied through simulation. The study presented in this paper proposes a process for developing an integrated dynamic modeling and simulation environment designed for understanding the behavior of the next generation naval ship which is envisioned to be self-sensing, self-assessing and self-reacting. Various models, including power model, fluid model and control model, are developed to investigate the functionalities of the naval ship systems. An object oriented approach is employed to validate the architectural design of the integrated simulation environment and a surrogate modeling technique is utilized to accelerate the simulation speed.

Examination of a Torpedo Performance Space and its Relation to the System Design Space

Presented at the 9th Multi-Disciplinary Analysis and Optimization Symposium in Atlanta, GA, September 4-6, 2002.

GVU-PROCAMS: enabling novel projected interfaces

Front projection allows large displays to be deployed relatively easily. However, it is sometimes difficult to find a location to place a projector, especially for ad-hoc installations. Additionally, front projection suffers from shadows and occlusions, making it ill-suited for interactive displays. The GVU-PROCAMS system allows programmers to deploy projectors and displays easily in arbitrary locations by enabling enhanced keystone correction via warping on 3D hardware. In addition, it handles the calibration of multiple projectors using computer vision to produce a redundantly illuminated surface. Redundant illumination offers robustness in the face of occlusions, providing a user with the experience of a rear-projected surface. This paper presents a stand-alone application (WinPVRP) and a programming system (GVU-PROCAMS) that easily allows others to create projected displays with enhanced warping and redundant illumination.

Design of a resource advisor for the next-generation surface combatant

The purpose of this project is to investigate the development of a resource advisor for the next-generation surface combatant of the US Navy. Reductions in crew size for these future vessels and increases in automation are likely to overburden the operators of these highly interdependent dynamical systems. The integrated engineering plant (IEP) is a dynamical network of interdependent systems that provide services to the ship such as awareness, mobility, etc. The heterogeneous systems composing the IEP, i.e.: electric distribution, chill water, fire main, etc, trade resources between themselves and the optimum configuration of the system is a multi-disciplinarian problem exhibiting highly dynamic characteristics

Benefits of Non-Dimensionalization in Creation of Designs of Experiments for Sizing Torpedo Systems

Presented at the 10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, Albany, NY, August 30-September 1, 2004.

Simulation of Distributed Co-Crack Propagation in Cellular Automata by Time Warp Synchronization

Damage tolerance design is a philosophy used to refine fail safe design, especially for the aircraft design field. This design concept predicts structural failure, assuming that cracks exist and will grow large enough to produce failures. Calculation of crack propagation in global aspect as like wing requires a solution of complex system by considering crack opening or crack closure. When analyzing multiple cracks, this behavior becomes more complex. In this paper, the aircraft wing is modeled based NASA Common Research Model (CRM) and simulations are performed to observe the multiple crack propagation that are almost impossible to examine in real environmental tests because of its cost and complexity. The Structural Common Research Model (SCRM) is developed by creating internal structures from the CRM for the simulation. The simulation is performed with two level hierarchical models. At the macro level, the SCRM is used as a general finite element model to get static stress and analyzed with strain-life approach as crack initiation analysis (CIA). If a crack is initialized in a certain element, then the element is considered as a base model to build the micro level environment. This micro level analysis is performed by Linear Elastic Fracture Mechanics (LEFM) to calculate crack propagation using Cellular Automata (CA). CA is an effective way to solve a complex system by working without central control and performing with simple local rules of operation. CA local rule is employed that a cell is regarded as a dead cell if the residual strength calculated based on LEFM approaches a critical factor. Dead cells become acting cavities in the model and induce a reduction in strength for neighboring cells. The cellular model acts automatically following cyclic load from the history spectrum. Transport Wing Standard spectrum (TWIST) is selected to represent the test loading spectrum in order to simulate the transport aircraft wing. Crack propagation at the micro level is performed by independent calculations for each CA model which is originally from SCRM. So they can be easily distributed in parallel computing given that each crack propagation process is treated as a logical process. But, a synchronization algorithm is required to consider interaction effects when two cracks get close enough. The Time Warp algorithm was selected for the synchronization manager. Since Time Warp allows violation of local causality constraint mechanism, the parallel analysis of distributed crack propagation can be achieved more optimistic way. In result, CIA is accomplished and generated initial crack cycle information for every element in macro wing model. Crack propagation analysis is performed following local rule, neighboring cells rule, and updating rule of CA. This result makes it possible to estimate the design safety withhold accounting for in-service or manufacturing defects. This simulation method also raises up the possibility of evaluation the safety of complex system for both macro and micromechanical aspects.

Inference of Aerodynamic Loads Under Uncertainty Using Strain Measurements and Bayesian Networks

The aerodynamic loads on a commercial transport aircraft are generally well known for a set of flight conditions. However, external phenomena such as wing contamination or the loss of natural laminar airflow (NLF) can create a slight shift in the aerodynamic loads. Although their effect on the loads is small, their consequence on the flight performance is important and current methods to detect those phenomena are rather complex. This paper presents a method based on Bayesian Networks (BN) to analyze the effect of adding strain sensors in a wing structure for two purposes. First, they could be used to reduce the uncertainty on the aerodynamic load prediction to possibly detect the loss of NLF or wing contamination (anomaly detection). Second, this method could contribute to inferring the flight condition with the objective of increasing the reliability of the monitoring system or reducing the number of sensors required on small aircraft such as Unmanned air vehicles (UAV). The methodology is applied to the Common Research Model (CRM), a B777 size aircraft augmented with an in-house designed structure. It is shown that the uncertainty on the aerodynamic loads can be reduced by 94% and that the flight conditions can be inferred within 5% for the Mach number and 9% for the fuel mass of the initial range by using only five strain measurements in the wing.