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DCS-Neural-Network Program for Aircraft Control and Testing

A computer program implements a dynamic-cell-structure (DCS) artificial neural network that can perform such tasks as learning selected aerodynamic characteristics of an airplane from windtunnel test data and computing realtime stability and control derivatives of the airplane for use in feedback linearized control. A DCS neural network is one of several types of neural networks that can incorporate additional nodes in order to rapidly learn increasingly complex relationships between inputs and outputs. In the DCS neural network implemented by the present program, the insertion of nodes is based on accumulated error. A competitive Hebbian learning rule (a supervised-learning rule in which connection weights are adjusted to minimize differences between actual and desired outputs for training examples) is used. A Kohonen-style learning rule (derived from a relatively simple training algorithm, implements a Delaunay triangulation layout of neurons) is used to adjust node positions during training. Neighborhood topology determines which nodes are used to estimate new values. The network learns, starting with two nodes, and adds new nodes sequentially in locations chosen to maximize reductions in global error. At any given time during learning, the error becomes homogeneously distributed over all nodes.

Posted in: Briefs, TSP

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Infrastructure for Rapid Development of Java GUI Programs

The Java Application Shell (JAS) is a software framework that accelerates the development of Java graphical-userinterface (GUI) application programs by enabling the reuse of common, proven GUI elements, as distinguished from writing custom code for GUI elements. JAS is a software infrastructure upon which Java interactive application programs and graphical user interfaces (GUIs) for those programs can be built as sets of plug-ins. JAS provides an application- programming interface that is extensible by application-specific plugins that describe and encapsulate both specifications of a GUI and applicationspecific functionality tied to the specified GUI elements. The desired GUI elements are specified in Extensible Markup Language (XML) descriptions instead of in compiled code. JAS reads and interprets these descriptions, then creates and configures a corresponding GUI from a standard set of generic, reusable GUI elements. These elements are then attached (again, according to the XML descriptions) to applicationspecific compiled code and scripts. An application program constructed by use of JAS as its core can be extended by writing new plug-ins and replacing existing plug-ins. Thus, JAS solves many problems that Java programmers generally solve anew for each project, thereby reducing development and testing time.

Posted in: Briefs, TSP

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Generic Environment for Simulating Launch Operations

GEM-FLO (A Generic Simulation Environment for Modeling Future Launch Operations) is a computer program that facilitates creation of discreteevent simulation models of ground processes in which reusable or expendable launch vehicles (RLVs) are prepared for flight. GEM-FLO includes a component, developed in Visual Basic, that generates a graphical user interface (GUI) and a component, developed in the Arena simulation language, that creates a generic discrete-event simulation model. Through the GUI, GEM-FLO elicits RLV design information from the user. The design information can include information on flight hardware elements, resources, and ground processes. GEMFLO translates the user’s responses into mathematical variables and expressions that populate the generic simulation model. The variables and expressions can represent processing times, resource capacities, status variables, and other process parameters needed to configure a simulation model that reflects the ground processing flow and requirements of a specific RLV. Upon execution of the model, GEM-FLO puts out data on many measures of performance, including the flight rate, turnaround time, and utilization of resources. This information can serve as the basis for determining whether design goals can be met, and for comparing characteristics of competing RLV designs.

Posted in: Briefs

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Modular Aero-Propulsion System Simulation

The Modular Aero-Propulsion System Simulation (MAPSS) is a graphical simulation environment designed for the development of advanced control algorithms and rapid testing of these algorithms on a generic computational model of a turbofan engine and its control system. MAPSS is a nonlinear, non-real- time simulation comprising a Component Level Model (CLM) module and a Controller-and-Actuator Dynamics (CAD) module. The CLM module simulates the dynamics of engine components at a sampling rate of 2,500 Hz. The controller submodule of the CAD module simulates a digital controller, which has a typical update rate of 50 Hz. The sampling rate for the actuators in the CAD module is the same as that of the CLM. MAPSS provides a graphical user interface that affords easy access to engine-operation, engine-health, and control parameters; is used to enter such input model parameters as power lever angle (PLA), Mach number, and altitude; and can be used to change controller and engine parameters. Output variables are selectable by the user. Output data as well as any changes to constants and other parameters can be saved and reloaded into the GUI later.

Posted in: Briefs, TSP

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Processing Raman Spectra of High-Pressure Hydrogen Flames

The Raman Code automates the analysis of laser-Raman- spectroscopy data for diagnosis of combustion at high pressure. On the basis of the theory of molecular spectroscopy, the software calculates the rovibrational and pure rotational Raman spectra of H2, O2, N2, and H2O in hydrogen/air flames at given temperatures and pressures. Given a set of Raman spectral data from measurements on a given flame and results from the aforementioned calculations, the software calculates the thermodynamic temperature and number densities of the aforementioned species. The software accounts for collisional spectral-linebroadening effects at pressures up to 60 bar (6 MPa). The line-broadening effects increase with pressure and thereby complicate the analysis. The software also corrects for spectral interference (“crosstalk”) among the various chemical species. In the absence of such correction, the cross-talk is a significant source of error in temperatures and number densities. This is the first known comprehensive computer code that, when used in conjunction with a spectral calibration database, can process Raman-scattering spectral data from high-pressure hydrogen/ air flames to obtain temperatures accurate to within ±10 K and chemicalspecies number densities accurate to within ±2 percent.

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Card Provides PCI-Based Multi-Axis Motion Control

Performance Motion Devices (Lincoln, MA) offers the Prodigy™-PCI motion card for multi-axis motion control. Available in 1-, 2-, 3-, and 4-axis versions, the card provides trajectory generation, performance trace, on-the-fly changes, and commutation. Motor type can be software- selected on a per-axis basis, and includes DC brush, brushless DC, step, and microstepping. The card communicates via a PCI bus, CANbus, or serial port. Card features include S-curve, trapezoidal, velocity contouring, electronic gearing, and user-generated profile modes. The card accepts input parameters such as position, velocity, acceleration, and jerk from the host, and generates a corresponding trajectory.

Posted in: Products, Products

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Telecom Adapter for Intra-Chassis Communication

Performance Technologies (Rochester, NY) has expanded its family of communication platforms with the PCE385, a quad T1/E1/J1 PCI Express telecom adapter. The device is enabled with NexusWare Core®, the company’s Linux-based software, and includes an onboard MPC8280 PowerQUICC II™ RISC communications processor. It offers various signaling and communications protocols including SIP, SS7 MTP-2, and ISDN and WAN connectivity with Frame Relay, HDLC, LAPD, and X.25.

Posted in: Products, Products

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