Closed-loop autonomous docking system

An autonomous docking system is provided which produces commands for the steering and propulsion system of a chase vehicle used in the docking of that chase vehicle with a target vehicle. The docking system comprises a passive optical target affixed to the target vehicle and comprising three reflective areas including a central area mounted on a short post, and tracking sensor and process controller apparatus carried by the chase vehicle. The latter apparatus comprises a laser diode array for illuminating the target so as to cause light to be reflected from the reflective areas of the target; a sensor for detecting the light reflected from the target and for producing an electrical output signal in accordance with an image of the reflected light; a signal processor for processing the electrical output signal in accordance with an image of the reflected light; a signal processor for processing the electrical output signal and for producing, based thereon, output signals relating to the relative range, roll, pitch, yaw, azimuth, and elevation of the chase and target vehicles; and a docking process controller, responsive to the output signals produced by the signal processor, for producing command signals for controlling the steering and propulsion system of the chase vehicle

Autoguidance video sensor for docking

The Automated Rendezvous and Docking system (ARAD) is composed of two parts. The first part is the sensor which consists of a video camera ringed with two wavelengths of laser diode. The second part is a standard Remote Manipulator System (RMS) target used on the Orbiter that has been modified with three circular pieces of retro-reflective tape covered by optical filters which correspond to one of the wavelengths of laser diode. The sensor is on the chase vehicle and the target is on the target vehicle. The ARAD system works by pulsing one wavelength laser diodes and taking a picture. Then the second wavelength laser diodes are pulsed and a second picture is taken. One picture is subtracted from the other and the resultant picture is thresholded. All adjacent pixels above threshold are blobbed together (X and Y centroids calculated). All blob centroids are checked to recognize the target out of noise. Then the three target spots are windowed and tracked. The three target spot centroids are used to evaluate the roll, yaw, pitch, range, azimuth, and elevation. From that a guidance routine can guide the chase vehicle to dock with the target vehicle with the correct orientation

Reassessment of Acarbose as a Transition State Analogue Inhibitor of Cyclodextrin Glycosyltransferase

The binding of several different active site mutants of Bacillus circulans cyclodextrin glycosyltransferase to the inhibitor acarbose has been investigated through measurement of Ki values. The mutations represent several key amino acid positions, most of which are believed to play important roles in governing the product specificity of cyclodextrin glycosyltransferase. Michaelis-Menten parameters for the substrates α-maltotriosyl fluoride (αG3F) and α-glucosyl fluoride (αGF) with each mutant have been determined by following the enzyme-catalyzed release of fluoride with an ion-selective fluoride electrode. In both cases, reasonable correlations are observed in logarithmic plots relating the Ki value for acarbose with each mutant and both kcat/Km and Km for the hydrolysis of either substrate by the corresponding mutants. This indicates that acarbose, as an inhibitor, is mimicking aspects of both the ground state and the transition state. A better correlation is observed for αGF (r = 0.98) than αG3F (r = 0.90), which can be explained in terms of the modes of binding of these substrates and acarbose. Re-refinement of the previously determined crystal structure of wild-type CGTase complexed with acarbose reveals a binding mode consistent with the transition state analogue character of this inhibitor.

Directing the Basic Communication Course: Eighteen Years Later

We focused on three problems that evolve over time for veteran basic course directors. After briefly commenting on the state of basic course literature, we discuss dealing with tradition, motivating students for the long term, and maintaining our own motivation for the course — three areas quite distinct from those addressed in an earlier article. The ideas and issues discussed here have arisen as a result of eighteen years of directing a basic communication course

Teaching Basic Courses: Problems and Solutions

Basic speech courses enroll many students. Basic course instructors are often under great pressure to succeed and to be effective. Because of the numbers of students and the pressures, they experience many problems. Five are discussed in this article: rigor versus leniency, independence versus dependence, theory versus skills, being close versus being distant, and objective evaluation versus subjective evaluation. Solutions to these problems are likely to affect both student and instructor motivation. Solutions are also likely to affect how students perceive instructors. That\u27s why, with respect to basic course instructors, you have to have solutions for the problems

Utah Water Quality- Utah Ground Water

Ground water is important to the economic and physical well-being of the people of Utah. About 95% of Utah\u27s fresh water is ground water. It provides more than 70% of the state\u27s drinking water and is a major source of water for agriculture and irrigation

Averting shallow well contamination in Uganda

Averting shallow well contamination in Ugand

Utah Water Quality- Fertilizer Impact on Groundwater in Utah

Water quality has become the focal point of many decisions involving crop production. Crop production depends on specific inputs including fertilizer application. Without proper fertilization a farmer cannot achieve maximum economic returns. Crop yields in Utah have been increased over 50% by nitrogen fertilizer application alone. However, increasing nitrogen application beyond that needed for optimum economic return does more harm than good. This is especially true when groundwater concerns are addressed

Pesticide Movement in Response to Furrow Irrigation and Pesticide Parameters

Production of adequate supplies of food and fiber currently requires that pesticides be used to limit crop losses from insects, pathogens, weeds and other pests. The term pesticide refers to a large number ofchemical compounds. Pesticides include acaricides, fungicides, herbicides, insecticides, nematicides, algicides, arboricides, zoocides, and many more

Optimal flexibility for conformational transitions in macromolecules

Conformational transitions in macromolecular complexes often involve the reorientation of lever-like structures. Using a simple theoretical model, we show that the rate of such transitions is drastically enhanced if the lever is bendable, e.g. at a localized "hinge''. Surprisingly, the transition is fastest with an intermediate flexibility of the hinge. In this intermediate regime, the transition rate is also least sensitive to the amount of "cargo'' attached to the lever arm, which could be exploited by molecular motors. To explain this effect, we generalize the Kramers-Langer theory for multi-dimensional barrier crossing to configuration dependent mobility matrices.Comment: 4 pages, 4 figure