Information Technology & Software

Software for Analyzing Forth Programs

Various parts of code can be categorized and quantified in selectable ways.

Forth Source Code Analysis Tool Set (FSCATS) is a computer program that provides a wide range of capabilities for documenting, analyzing, and reverse-engineering computer programs written in the Forth programming language. FSCATS also aids in the management of software, estimating costs of software, and development of metrics for characterizing software.

Posted in: Briefs, Information Sciences, CAD, CAM, and CAE, Computer software and hardware

Rapid-Prototyping Virtual-Reality Software Tool Kit

The user need not engage in a tedious learning process.

The VrTool computer program enables its user to rapidly develop a prototype virtual-reality (VR) application program. Users of VR application programs need software that can help them keep pace with the rapidly evolving VR field. None of the previously commercially available VR software tool kits affords rapid-prototyping capabilities because all require users to generate their own code. This makes it necessary for users to engage in a tedious learning process to gain understanding of the application-program-generation process, which is also tedious.

Posted in: Briefs, Information Sciences, Rapid prototyping, Virtual reality, Computer software and hardware

Program for Parallel Distributed Processing

This software package automatically distributes mutually independent tasks to networked workstations.

A software system has been devised to manage automatically (1) the distribution of mutually independent computing tasks to computer workstations in NASA's Flight Design and Analysis System (FADS) network and (2) the execution of those tasks on those workstations. This program parallelizes serial tasks, making it possible to execute them concurrently. This program is a substantial improvement over previously developed special-purpose parallel-processing software systems used by NASA.

Posted in: Briefs, Information Sciences, CAD, CAM, and CAE, Computer software and hardware, Performance upgrades, Spacecraft

Subpixel Map Registration and Estimation of Uncertainty

A normal distribution is fitted to the peak of a likelihood function in a pose space.

A method of determining the location and the uncertainty in the location of a mobile robot to subpixel resolution on a map grid has been devised. The method is applicable to a robot equipped with stereoscopic vision equipment for mapping the local terrain and with sensors for determining its orientation. The method involves fitting a parameterized surface (usually a normal distribution) to the peak of a likelihood function in the space of possible positions.

Posted in: Briefs, TSP, Information Sciences

A Method for Designing Low-Pass FIR Digital Filters

Time-domain filters are first constructed in the frequency domain, using special window functions.

A class of finite-impulse-response (FIR) digital filters has been developed to perform certain frequency-limiting, decimation, and differentiation (with respect to time) functions on a time series of data samples. The method is implemented by use of design equations that contain parameters that can be adjusted to obtain the desired functionality while limiting such undesired effects as aliasing and gain ripple. The original application is processing of a time series of raw range data from the proposed Gravity Recovery and Climate Experiment (GRACE), in which microwave phase tracking between two small spacecraft orbiting the Earth would yield the time-tagged raw range data, which would be processed to extract information on the structure of the gravitational field of the Earth. The method is general enough to be applicable in other situations that involve similar signal-processing requirements.

Posted in: Briefs, TSP, Information Sciences, Mathematical analysis, Measurements, Spacecraft

Preconditioning the Helmholtz Equation for a 2-D Duct

Numerical solutions converge quickly to exact steady-state solutions.

A preconditioning technique has been developed for numerical solution of the Helmholtz equation as applied to the steady-state propagation of sound in a semi-infinite, two-dimensional (2-D) rigid duct. As explained below, the technique involves the use of two pseudo-time parameters in a finite-difference approximation of the equation that describes the propagation of sound. The use of these parameters makes the solution proceed much faster than in older transient- and steady-state-analysis-based numerical solution methods.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Statistical analysis, Acoustics

Analytic Technique for Separation of Cochannel FM Signals

In the absence of noise, two signals can be separated perfectly.

A digital processing technique for separating two cochannel frequency-modulation (FM) signals involves a partial algebraic solution that gives the phases of the two signals to within one of two possibilities, plus the use of a two-state trellis algorithm to trace the most likely correct sequence of possibilities. Other techniques for separating cochannel FM signals do not yield perfect separation under any circumstances; however, the present technique can yield perfect separation in the absence of noise.

Posted in: Briefs, Information Sciences, Mathematical models, Communication protocols

Parameterizing Shape Perturbations for Multidisciplinary Design Optimization

Shapes are deformed by use of soft-objects animation algorithms.

A recently developed method of parameterizing complex shapes that one seeks to optimize differs from prior such methods in two major respects: (1) instead of entirely parameterizing the shapes, one parameterizes only shape perturbations (deformations of initial or baseline shapes) and (2) the deformations are computed by soft-objects animation (SOA) algorithms commonly used in computer graphics. This method is suitable for multidisciplinary design-optimization processes, in which shapes of structures are optimized along with other aspects of design (e.g., aerodynamics). This method can be applied, for example, to the shapes of both exterior aerodynamic surfaces and internal structural components of aircraft.

Posted in: Briefs, Information Sciences, CAD, CAM, and CAE, Mathematical models, Optimization, Imaging and visualization

Developmental Software for Exploiting Hyperspectral Imagery

Evolutionary computing techniques are used.

A unique state-of-the-art process for exploiting hyperspectral satellite imagery, based on evolutionary computing methods, has been developed and a proof-of-concept demonstration has been conducted. This development is projected to lead to several important commercial products, including a fully integrated, high-payoff, user-friendly software package — the Integrated Hyperspectral Imagery Analysis Toolbox. This software would be capable of end-to-end processing of industrial and governmental hyperspectral satellite image data with extensions to several popular commercial software products like ENVI from Research Systems, Inc., and ESRI's ArcView Geographical Information System. The development of the end product will focus on accurate detection and identification of natural and artificial materials and objects, the use of large libraries of laboratory reference data, and ease of use. Potential commercial applications include assessment of crops (including estimation of crop yields), exploration for minerals and oil, planning of military missions and automated identification of military targets, urban planning, environmental assessment, and search-and-rescue operations.

Posted in: Briefs, Information Sciences, Computer software and hardware, Imaging and visualization, Satellites

Algorithm for Rapid Acquisition of a PPM Optical Signal

Data frames can be synchronized with part of the synchronization sequence.

An algorithm for rapid acquisition of a pulse-position-modulation (PPM) optical data signal implements a pattern-matching technique for synchronization of receiver timing with the temporal boundaries of data frames. Synchronization is necessary because in PPM, information is conveyed by the time slot during which a pulse is detected. Fast acquisition of a signal depends on detection of pulses in noise, and on correct estimation of the times of detected pulses. To facilitate synchronization at the receiver, a transmitter periodically inserts a prescribed sequence of pulses — the synchronization sequence or word — into the transmitted data stream. Older PPM-signal-acquisition algorithms are based on correlations and depend on reception of the full synchronization word (128 bytes long in some applications). The present algorithm is more computationally efficient and is capable of achieving synchronization with part of the synchronization word — typically with as few as 2 to 6 bytes.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Optics, Wireless communication systems

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