How scaling of the disturbance set affects robust positively invariant sets for linear systems

This paper presents new results on robust positively invariant (RPI) sets for linear discrete-time systems with additive disturbances. In particular, we study how RPI sets change with scaling of the disturbance set. More precisely, we show that many properties of RPI sets crucially depend on a unique scaling factor which determines the transition from nonempty to empty RPI sets. We characterize this critical scaling factor, present an efficient algorithm for its computation, and analyze it for a number of examples from the literature

Effects of microgravity on growth hormone concentration and distribution in plants

On earth, gravity affects the distribution of the plant growth hormone, indole-3-acetic acid (IAA), in a manner such that the plant grows into a normal vertical orientation (shoots up, roots down). How the plant controls the amount and distribution of IAA is only partially understood and is currently under investigation in this laboratory. The question to be answered in the flight experiment concerns the effect of gravity on the concentration, turn over, and distribution of the growth hormone. The answer to this question will aid in understanding the mechanism by which plants control the amount and distribution of growth hormone. Such knowledge of a plant's hormonal metabolism may aid in the growth of plants in space and will lead to agronomic advances

Radiation Dosimetry via Automated Fluorescence Microscopy

A developmental instrument for assessment of radiation-induced damage in human lymphocytes includes an automated fluorescence microscope equipped with a one or more chargecoupled- device (CCD) video camera(s) and circuitry to digitize the video output. The microscope is also equipped with a three-axis translation stage that includes a rotation stage, and a rotary tray that holds as many as thirty specimen slides. The figure depicts one version of the instrument. Once the slides have been prepared and loaded into the tray, the instrument can operate unattended. A computer controls the operation of the stage, tray, and microscope, and processes the digital fluorescence-image data to recognize and count chromosomes that have been broken, presumably by radiation. The design and method of operation of the instrument exploit fluorescence in situ hybridization (FISH) of metaphase chromosome spreads, which is a technique that has been found to be valuable for monitoring the radiation dose to circulating lymphocytes. In the specific FISH protocol used to prepare specimens for this instrument, metaphase lymphocyte cultures are chosen for high mitotic index and highly condensed chromosomes, then several of the largest chromosomes are labeled with three of four differently colored whole-chromosome-staining dyes. The three dyes, which are used both individually and in various combinations, are fluorescein isothiocyanate (FITC), Texas Red (or equivalent), and Cy5 (or equivalent); The fourth dye 4',6-diamidino- 2-phenylindole (DAPI) is used as a counterstain. Under control by the computer, the microscope is automatically focused on the cells and each slide is scanned while the computer analyzes the DAPI-fluorescence images to find the metaphases. Each metaphase field is recentered in the field of view and refocused. Then a four-color image (more precisely, a set of images of the same view in the fluorescent colors of the four dyes) is acquired. By use of pattern-recognition software developed specifically for this instrument, the images in the various colors are processed to recognize the metaphases and count the chromosome fragments of each color within the metaphases. The intermediate results are then further processed to estimate the proportion of cells that have suffered genetic damage. The prototype instrument scans at an average areal rate of 4.7 mm2/h in unattended operation, finding about 14 metaphases per hour. The false-alarm rate is typically less than 3 percent, and the metaphase-miss rate has been estimated to be less than 5 percent. The counts of chromosomes and fragments thereof are 50 to 70 percent accurate

Automated Global Feature Analyzer - A Driver for Tier-Scalable Reconnaissance

For the purposes of space flight, reconnaissance field geologists have trained to become astronauts. However, the initial forays to Mars and other planetary bodies have been done by purely robotic craft. Therefore, training and equipping a robotic craft with the sensory and cognitive capabilities of a field geologist to form a science craft is a necessary prerequisite. Numerous steps are necessary in order for a science craft to be able to map, analyze, and characterize a geologic field site, as well as effectively formulate working hypotheses. We report on the continued development of the integrated software system AGFA: automated global feature analyzerreg, originated by Fink at Caltech and his collaborators in 2001. AGFA is an automatic and feature-driven target characterization system that operates in an imaged operational area, such as a geologic field site on a remote planetary surface. AGFA performs automated target identification and detection through segmentation, providing for feature extraction, classification, and prioritization within mapped or imaged operational areas at different length scales and resolutions, depending on the vantage point (e.g., spaceborne, airborne, or ground). AGFA extracts features such as target size, color, albedo, vesicularity, and angularity. Based on the extracted features, AGFA summarizes the mapped operational area numerically and flags targets of "interest", i.e., targets that exhibit sufficient anomaly within the feature space. AGFA enables automated science analysis aboard robotic spacecraft, and, embedded in tier-scalable reconnaissance mission architectures, is a driver of future intelligent and autonomous robotic planetary exploration

GIS Applications

This roundtable discusses various GIS applications in different fields. Purdue\u27s Center for Regional Development presents harmonized space-time data and measures: a study of race, ethnicity and poverty . Prof. Darrell Schulze from Agronomy and Purdue Center for Environmental and Regulatory Information Systems showcase SoilExplorer, a soil map application for teaching and learning soil science. Mark Ehle, Tippcanoe County GIS administrator, introduces the county\u27s GIS services and maps

A Foldable, Compact and Lightweight Solar Array Substrate with Large Deployed Wingspan for Small Spacecraft

A solar array (SA) mechanical subsystem made of thin and lightweight substrates was developed, built and tested for a small spacecraft. The SA is compactly foldable and deployable to a length of approximately five times the widthof the spacecraft. It has miniature hinges and latches, and deploys freely without dampers and synchronizing mechanisms. The solar cell interconnect harness consists ofthin, laminatedflexible circuits,and the substrates feature a syntactic foam core exposed to large temperature extremes. This developmental technology, currently at TRL 6, when completely proven out, would be viable for small satellites and would enable missions in the Express-class. The Express-class (or Express) refers to satellites in the range of 25kg to 100 kg that are positioned in the gap between 12U CubeSats and small ESPA-class spacecraft. Cornerstones of the SA development were compact packaging, deployment dynamic simulation, and hinge-latch tuning for dynamics and lock-up loads. Dynamic deployment simulations were modeled in Adams to observe the behavior of the unfolding array, to size the hinge springs and to monitor the lockup loads at the substrate to hinge interfaces. Extensive substrate mechanical and thermal tests were conducted to verify the substrate’s structural capability and dimensional stability in its operating environment. Thermal tests were carried out to observe the effect of mismatching coefficients of thermal expansion between the adhered flexible laminated interconnect circuits and the substrate. Gravity-negated wing deployment tests were performed at temperature limits and in vacuum to verify the overall design intent of the deployment. The stowed wing was vibration tested to verify its structural capabilities under launch environments, and then deployment tested again to demonstrate that the array as a mechanism was unaffected by launch loads. Mechanically, the Express SA substrate assembly has been advanced in its development and proven out as a structure and mechanism. Further development of the electrical power system is necessary, and additional testing for mechanical and thermal interactions of the solar cells with the overall SA substrate will need to be done. This SA subsystem would be an essential expansion to the Express hardware developed by The Applied Physics Laboratory (APL) for the advancement and enablement of Express-class missions