Software

Control Code for Bearingless Switched-Reluctance Motor

A computer program has been devised for controlling a machine that is an integral combination of magnetic bearings and a switched-reluctance motor. The motor contains an eightpole stator and a hybrid rotor, which has both (1) a circular lamination stack for levitation and (2) a six-pole lamination stack for rotation. The program computes drive and levitation currents for the stator windings with real-time feedback control. During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. This version is executable in a control-loop time of 40 μs on a Pentium (or equivalent) processor that operates at a clock speed of 400 MHz. The program can be expanded, by addition of logic blocks, to enable control of position along additional axes. The code enables adjustment of operational parameters (e.g., motor speed and stiffness, and damping parameters of magnetic bearings) through computer keyboard key presses.

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Simulating Flights of Future Launch Vehicles and Spacecraft

Marshall Aerospace Vehicle Representation in C (MAVERIC) is a computer program for generic, low-to-high-fidelity simulation of the flight(s) of one or more launch vehicle(s) or spacecraft. MAVERIC is designed to accommodate multi-staged vehicles, powered serially or in parallel, with multiple engines, tanks, and cargo elements. Engines can be of jet or conventional rocket types, using either liquid or solid propellants.

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TMS for Instantiating a Knowledge Base With Incomplete Data

A computer program that belongs to the class known among software experts as output truth-maintenance systems (output TMSs) has been devised as one of a number of software tools for reducing the size of the knowledge base that must be searched during execution of artificial-intelligence software of the rule-based inference engine type in a case in which data are missing. This program determines whether the consequences of activation of two or more rules can be combined without causing a logical inconsistency. For example, in a case involving hypothetical scenarios that could lead to turning a given device on or off, the program determines whether a scenario involving a given combination of rules could lead to turning the device both on and off at the same time, in which case that combination of rules would not be included in the scenario.

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Automated Design of Restraint Layer of an Inflatable Vessel

A Mathcad computer program largely automates the design and analysis of the restraint layer (the primary load-bearing layer) of an inflatable vessel that consists of one or more sections having cylindrical, toroidal, and/or spherical shape(s). A restraint layer typically comprises webbing in the form of multiple straps. The design task includes choosing indexing locations along the straps, computing the load at every location in each strap, computing the resulting stretch at each location, and computing the amount of undersizing required of each strap so that, once the vessel is inflated and the straps thus stretched, the vessel can be expected to assume the desired shape.

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Computational Workbench for Multibody Dynamics

PyCraft is a computer program that provides an interactive, workbench-like computing environment for developing and testing algorithms for multibody dynamics. Examples of multibody dynamic systems amenable to analysis with the help of PyCraft include land vehicles, spacecraft, robots, and molecular models. PyCraft is based on the Spatial-Operator-Algebra (SOA) formulation for multibody dynamics. The SOA operators enable construction of simple and compact representations of complex multibody dynamical equations. Within the PyCraft computational workbench, users can, essentially, use the high-level SOA operator notation to represent the variety of dynamical quantities and algorithms and to perform computations interactively. PyCraft provides a Python-language interface to underlying C++ code. Working with SOA concepts, a user can create and manipulate Python-level operator classes in order to implement and evaluate new dynamical quantities and algorithms. During use of PyCraft, virtually all SOA-based algorithms are available for computational experiments.

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Generating a 2D Representation of a Complex Data Structure

A computer program, designed to assist in the development and debugging of other software, generates a two-dimensional (2D) representation of a possibly complex ndimensional (where n is an integer >2) data structure or abstract rank-n object in that other software. The nature of the 2D representation is such that it can be displayed on a non-graphical output device and distributed by non-graphical means. The purpose served by this representation is to assist the user in visualizing and understanding the complex data structure or arbitrarily dimensioned object. This is the only known program that enables a programmer to map an n-dimensional data structure to a flat 2D space. This program does not depend upon the hardware characteristics of a particular output device, and can be executed on a variety of computers from different manufacturers. It can be distributed in source-code or binary-code form. It requires a Lisp compiler. It has no specific memory requirements and depends upon the other software with which it is used and application programs running in it. This software is implemented as a library that is called by, and becomes folded into, the developmental other software.

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Conversion Between Osculating and Mean Orbital Elements

Osculating/Mean Orbital Element Conversion (C version) (OSMEANC) is a C-language computer program that performs precise conversions between osculating and mean classical orbital elements. OSMEANC can be used for precise design of spacecraft missions and maneuvers and precise calculation of planetary orbits. The program accounts for the full complexity of gravitational fields, including aspherical and third-body effects. In comparison with prior software used for the same purposes, OSMEANC offers greater accuracy in conversion: By virtue of inclusion of high-order gravitational and third-body effects, variations in semimajor axes are calculated to meter-level accuracy. OSMEANC is delivered as a callable shared library. It can be built for any platform with a C compiler. The user interface is via a Python-language wrapper script that can be replaced by the user. OSMEANC is mature and is the product of a significant upgrade from a Fortran version that has been in use since 1991.

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