Special Coverage

Iodine-Compatible Hall Effect Thruster
Precision Assembly of Systems on Surfaces (PASS)
Development of a Novel Electrospinning System with Automated Positioning and Control Software
2016 Create The Future Design Contest Open For Entries
Clamshell Sampler
Shape Memory Alloy Rock Splitter
Deployable Extra-Vehicular Activity Platform (DEVAP) for Planetary Surfaces
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Development of Software for a Lidar-Altimeter Processor

A report describes the development of software for a digital processor that operates in conjunction with a finite-impulse-response (FIR) chip in a spaceborne lidar altimeter.Processing is started by a laserfire interrupt signal that is repeated at intervals of 25 ms. For the purpose of discriminating between returns from the ground and returns from such things as trees, buildings, and clouds, the software is required to scan digitized lidar-return data in reverse of the acquisition sequence in order to distinguish the last return pulse from within a commanded ground-return range window. The digitized waveform information within this range window is filtered through 6 matched filters, in the hardware electronics, in order to maximize the probability of finding echoes from sloped or rough terrain and minimize the probability of selecting cloud returns. From the data falling past the end of the range window, there is obtained a noise baseline that is used to calculate a threshold value for each filter. The data from each filter is analyzed by a complex weighting scheme and the filter with the greatest weight is selected. A region around the peak of the ground-return pulse associated with the selected filter is placed in telemetry, as well as information on its location, height, and other characteristics. The software requires many uplinked parameters as input. Included in the report is a discussion of major software-development problems posed by the design of the FIR chip and the need for the software to complete its process within 20 ms to fit within the overall 25-ms cycle.

Posted in: Briefs

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Algorithm Determines Wind Speed and Direction FromVenturi-Sensor Data

Speed and direction are calculated from the spatial distribution of pressure readings. An algorithm computes the velocity of wind from the readings of an instrument like the one described in “Three-Dimensional Venturi Sensor for Measuring Extreme Winds” (KSC-12435), NASA Tech Briefs, Vol. 27, No. 9 (September 2003), page 32. To recapitulate: The sensor has no moving parts and is a compact, rugged means of measuring wind vectors having magnitudes of as much as 300 mph (134 m/s). The sensor includes a Venturi gap bounded by a curved upper and a curved lower surface that are axisymmetric with respect to a vertical axis and mirror-symmetric with respect to a horizontal midplane. One of the curved surfaces is instrumented with multiple ports for measuring dynamic pressures (see figure). The sensor also incorporates auxiliary sensors for measuring temperature, relative humidity, and static atmospheric pressure.

Posted in: Briefs, TSP

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Feature-Identification and Data-Compression Software

A report discusses the continuing development of Windows Interface for Nominal Displacement Selection (WINDS), a computer program for automated analysis of images of the Sun and planets acquired by scientific instruments aboard spacecraft. WINDS is intended to afford capabilities for identification of features, measurement of displacements and velocities, analysis of terrain and of atmospheres, and synthesis of animation sequences of images of terrains and atmospheres from small sets of samples by use of velocity based interpolation. A major element of WINDS will be a nonlinear correlator capable of tracking small features in complex image sequences. For dynamic image sequences, the correlator will enable compression of data by factors >100. In processing image data, WINDS will take account of such factors as texture in image data, rotation of features during measurement intervals, effects of viewing and solar illumination angles, and vertical structures of atmospheres. WINDS will also take account of positions, aiming directions, and fields of view of cameras to determine three-dimensional feature structures by use of triangulation and stereoscopic analysis techniques.

Posted in: Briefs, TSP

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Masked Proportional Routing

This procedure enables adaptation to changing network conditions. Masked proportional routing is an improved procedure for choosing links between adjacent nodes of a network for the purpose of transporting an entity from a source node (“A”) to a destination node (“B”). The entity could be, for example, a physical object to be shipped, in which case the nodes would represent waypoints and the links would represent roads or other paths between waypoints. For another example, the entity could be a message or packet of data to be transmitted from A to B, in which case the nodes could be computer-controlled switching stations and the links could be communication channels between the stations. In yet another example, an entity could represent a workpiece while links and nodes could represent, respectively, manufacturing processes and stages in the progress of the workpiece towards a finished product. More generally, the nodes could represent states of an entity and the links could represent allowed transitions of the entity.

Posted in: Briefs, TSP

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Real-Time Adaptive Color Segmentation by Neural Networks

Changing images would be analyzed to detect features of interest. Artificial neural networks that would utilize the cascade error projection (CEP) algorithm have been proposed as means of autonomous, real-time,adaptive color segmentation of images that change with time.In the original intended application,such a neural network would be used to analyze digitized color video images of terrain on a remote planet as viewed from an uninhabited spacecraft approaching the planet.During descent toward the surface of the planet, information on the segmentation of the images into differently colored areas would be updated adaptively in real time to capture changes in contrast, brightness, and resolution, all in an effort to identify a safe and scientifically productive landing site and provide control feedback to steer the spacecraft toward that site. Potential terrestrial applications include monitoring images of crops to detect insect invasions and monitoring of buildings and other facilities to detect intruders.

Posted in: Briefs, TSP

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Product Lifecycle Management System Aligns Manufacturer's Design and Development

An aerospace equipment manufacturer uses PLM to improve collaboration among design and development systems worldwide. Smiths Aerospace, a leading trans-Atlantic aerospace equipment manufacturer, has grown dramatically in recent years through a combination of strategic acquisitions and major program wins. To maintain its key position in the supply chains of all major military and civil aircraft and engine manufacturers, the company needed to align its heterogeneous design and development systems around the world. In addition to aligning these systems,the company also wanted to integrate new divisions into its Product Lifecycle Management (PLM) system.

Posted in: Briefs

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Designing Application Software for DSP Chips

"Higher-level" programming languages and software help developers quickly set up and test an application. When it comes to building a digital signal processing (DSP) board, it is important not to neglect the requirements of the application code — the code that actually acquires and processes data to provide useful results. Developers can write code using the assembly language native for a chosen DSP chip, or they can use a higher-level language such as C or C++ that a compiler converts into the operating code for a specific DSP chip. Even higher-level tools and software applications let developers perform operations from menus or drag-and-drop lists of functions; the underlying code of the tool or application converts these graphical operations into the operating code for the specific DSP chip.

Posted in: Briefs

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