Simple computer method provides contours for radiological images

Computer is provided with information concerning boundaries in total image. Gradient of each point in digitized image is calculated with aid of threshold technique; then there is invoked set of algorithms designed to reduce number of gradient elements and to retain only major ones for definition of contour

Viking lander spacecraft battery

The Viking Lander was the first spacecraft to fly a sterilized nickel-cadmium battery on a mission to explore the surface of a planet. The significant results of the battery development program from its inception through the design, manufacture, and test of the flight batteries which were flown on the two Lander spacecraft are documented. The flight performance during the early phase of the mission is also presented

Navigation for Spin Stabilized Deep Space Planetary Spacecraft

Navigation for planetary missions is well understood as shown by the successful flights to Venus and Mars by the JPL Mariner spacecraft. However, when we consider the farther planets, such as Jupiter and ultimately Pluto, the trip time requirements are so .long (on the order of 2 years to Jupiter and 8 to 1 0 years to Pluto) that spacecraft reliability becomes the paramount consideration. A basic approach to achieving reliability is to simplify the spacecraft system as much as possible within the limits of mission objectives, which usually arise from the scientific payload. System simplicity and reliability can be greatly enhanced if the spacecraft system is spin stabilized, since this reduces control system requirements substantially and in general minimizes onbeard navigation tasks. However, spin stabilization itself imposes a number of problems which must be solved before such a simplifying technique can be adapted. As an illustration, the present Pioneer VI spacecraft is spin stabilized and has no onboard control requirements after the first few days of the mission; hence its lifetime appears to be limited only by the lifetime of the electronic components. Pioneer VI, shown in Figure 1, is injected in a heliocentric orbit while spinning and is then torqued by a nitrogen system to place its spin axis perpendicular to the plane of the ecliptic. A phased array antenna mounted along the spin axis then provides a fan beam pattern lying in the plane of the ecliptic, thus always illuminating the earth and assuring the constant communication with the DSIF for ranges up to 2 AU. All perturbing factors, such as solar pressure, have been accounted for and this spacecraft will apparently retain its attitude indefinitely. (There is a small change in body attitude during the course of 1/2 of the orbit around the sun but this change is cancelled out in the next 1/2 of the orbit)

First measurements of the flux integral with the NIST-4 watt balance

In early 2014, construction of a new watt balance, named NIST-4, has started at the National Institute of Standards and Technology (NIST). In a watt balance, the gravitational force of an unknown mass is compensated by an electromagnetic force produced by a coil in a magnet system. The electromagnetic force depends on the current in the coil and the magnetic flux integral. Most watt balances feature an additional calibration mode, referred to as velocity mode, which allows one to measure the magnetic flux integral to high precision. In this article we describe first measurements of the flux integral in the new watt balance. We introduce measurement and data analysis techniques to assess the quality of the measurements and the adverse effects of vibrations on the instrument.Comment: 7 pages, 8 figures, accepted for publication in IEEE Trans. Instrum. Meas. This Journal can be found online at http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=1

Advanced study of coastal zone oceanographic requirements for ERTS E and F

Earth Resources Technology Satellites E and F orbits and remote sensor instruments for coastal oceanographic data collectio

Hopf algebras and characters of classical groups

Schur functions provide an integral basis of the ring of symmetric functions. It is shown that this ring has a natural Hopf algebra structure by identifying the appropriate product, coproduct, unit, counit and antipode, and their properties. Characters of covariant tensor irreducible representations of the classical groups GL(n), O(n) and Sp(n) are then expressed in terms of Schur functions, and the Hopf algebra is exploited in the determination of group-subgroup branching rules and the decomposition of tensor products. The analysis is carried out in terms of n-independent universal characters. The corresponding rings, CharGL, CharO and CharSp, of universal characters each have their own natural Hopf algebra structure. The appropriate product, coproduct, unit, counit and antipode are identified in each case.Comment: 9 pages. Uses jpconf.cls and jpconf11.clo. Presented by RCK at SSPCM'07, Myczkowce, Poland, Sept 200