Software

Runge-Kutta Circular-Advection-Problem Solver

Release 3.0 of the Multi-Stage Runge-Kutta Circular Advection Solver is a computer program that solves the circular-advection problem by use of a general m-stage Runge-Kutta scheme (for m = 1, 2, and 4) on a Cartesian (x,y) grid with optimized coefficients. [The circular-advection problem, ¶u/¶t = (-y,x) × grad(u) is a classical model of convective phenomena suitable for studying the behaviors of algorithms.] The spatial discretization in this software is that of a cell-centered upwind finite-volume formulation. The software is presented as an extensible object-oriented class library arranged so that the components of the Runge-Kutta algorithm can be instantiated arbitrarily from within another computer program. The software includes a complete library wrapper that enables launching of the rest of the software from a command line by use of consistent UNIX-style filter conventions. The source code was developed by use of the Extreme Programming (also known, variously, as "eXtreme Programming" and "XP") methodology, and as such is self-revealing, modular, compact, extendable, and customizable. A unique feature of this program is a provision for comprehensive automated testing. All library classes are bundled with complete verification tests, both documenting the feature behavior and enabling extension by end users. Developers have instant feedback from the automated tests if their extensions conflict with the existing code base. Further, a full set of automated validation tests is included to prove various numerical definitions such as positivity or order property of the solver.

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Software for Mobile Data-Communication Networks

Mobile Router is operating system code residing in a network router allowing the router to provide mobile-ipv4 functionality for any attached nodes. Mobile Router enables the entire network to roam. It is no longer necessary for every node in the network to run mobile Internet Protocol (IP) software because Mobile Router provides this function. In addition, Mobile Router eliminates the need to reconfigure a router as it moves from one network to another network, even across network domains. For example, Mobile Router enables communication with aircraft via the lnternet and/or intranets. Information as weather data, air-traffic control messages, voice communications, and images could be transmitted to aircraft easily and inexpensively by use of Internet protocols. As another example, data-communication nodes running Mobile Router could be incorporated into ambulances to provide real-time data communications with hospitals and medical experts. Commercial applications could include the provision of mobile Internet connections for cargo and cruise ships, tour buses, passenger aircraft, and automobiles.

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Software for Onboard Autonomy of a Three-Spacecraft Mission

A system of software has been designed to enable autonomous operations of the three University-built miniature spacecraft of the Three Corner Sat mission, scheduled for launch in 2003. The main software subsystems and their functions are the following:

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ICAN/JAVA: Integrated Composite Analyzer Recoded in Java

The Integrated Composite Analyzer (ICAN) computer program, originally written in the FORTRAN language, has been completely recoded in Java to make it more widely usable. Whereas the original ICAN could be executed on only a limited number of platforms, ICAN/JAVA is compatible with almost all computers and operating systems. Moreover, whereas the original ICAN was applicable to only polymer-based composite materials containing circular fibers, ICAN/JAVA is applicable to diverse composites, including those that contain metal matrices, ceramic matrices, noncircular fibers, and/or particulate reinforcements. ICAN/JAVA can be used to simulate many aspects of the behavior and properties of a composite material and its constituent materials, including vibration-damping and electrical properties. The code includes provisions for three-way substructuring of fiber, interphase, and matrix constituents. Graphical output and telescoping of scale are available. The code includes an on-line user's manual. The Java Runtime Environment software, which can be downloaded free of charge for most platforms, is necessary for execution of ICAN/JAVA.

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Software for Multidisciplinary Analysis With Parallelization

HiMAP is an advanced, portable software system that implements highly modular, parallel computation of the possibly nonlinear, coupled behaviors of aeroelastic and other complex systems that comprise subsystems, each of which is modeled by use of software formulated within a separate technological discipline (e.g., fluid dynamics, structural dynamics, and controls). HiMAP is designed to be executed on massively parallel processors (MPPs) and workstation clusters based on a multiple-instruction, multiple-data architecture. Software for solving the differential equations of the fluids discipline (the Navier-Stokes equations) is parallelized according to a zonal approach; that of the structures discipline is parallelized according to a substructures approach. Computations within each discipline are spread across processors by use of a standard message-passing interface (MPI) for interprocessor communications. Computations that involve exchange of information among disciplines are parallelized by use of MPIAPI — a utility software library that flexibly allocates a group of processors and enables communication between processors within the same group or in different groups. Additional parallelization for multiple-parameter cases is implemented by use of a script software subsystem. The combined effect of the three levels of parallelization is an almost linear scaleability for multiple concurrent analyses performed efficiently on MPPs.

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Software for Monitoring Performance of Other Software

Performance Logging Services (PLS) is a software utility that tracks the performance of another program in terms of statistics of timing and use of memory buffers. The monitored program must utilize either the UNIX or the VxWorks operating system. PLS can monitor performance requirements in real time and uses minimal memory and central-processing-unit (CPU) resources. It can measure software timing events with an accuracy of less than 50 µs. PLS consists of (1) a library of application-program interfaces (APIs) and (2) a performance-control-tool subprogram. The APIs are incorporated into a program to be monitored by simply compiling them with the program code. During execution, the APIs update performance statistics in shared memory, to which an external program can gain access. An operator can use the performance-control tool to gain access to the statistics, reset the statistics, and set control limits (essentially, upper and lower limiting values of statistics). The performance-control tool includes a trigger that can be used to start another program when the control limits are exceeded. Data from the triggered program is used to find the source of timing glitches and/or otherwise assist in troubleshooting when performance requirements are out of specification.

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Analyzing Aeroelasticity in Turbomachines

ASTROP2-LE is a computer program that predicts flutter and forced responses of blades, vanes, and other components of such turbomachines as fans, compressors, and turbines. ASTROP2-LE is based on the ASTROP2 program, developed previously for analysis of stability of turbomachinery components. In developing ASTROP2-LE, ASTROP2 was modified to include a capability for modeling forced responses. The program was also modified to add a capability for analysis of aeroelasticity with mistuning and unsteady aerodynamic solutions from another program, LINFLX2D, that solves the linearized Euler equations of unsteady two-dimensional flow. Using LINFLX2D to calculate unsteady aerodynamic loads, it is possible to analyze effects of transonic flow on flutter and forced response. ASTROP2-LE can be used to analyze subsonic, transonic, and supersonic aerodynamics and structural mistuning for rotors with blades of differing structural properties. It calculates the aerodynamic damping of a blade system operating in airflow so that stability can be assessed. The code also predicts the magnitudes and frequencies of the unsteady aerodynamic forces on the airfoils of a blade row from incoming wakes. This information can be used in high-cycle-fatigue analysis to predict the fatigue lives of the blades.

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