Thermal environment

Human tolerance in thermal environment, thermal physiology of space clothing, and biothermal considerations in space cabin desig

Science Verification Results from PMAS

PMAS, the Potsdam Multi-Aperture Spectrophotometer, is a new integral field instrument which was commissioned at the Calar Alto 3.5m Telescope in May 2001. We report on results obtained from a science verification run in October 2001. We present observations of the low-metallicity blue compact dwarf galaxy SBS0335-052, the ultra-luminous X-ray Source X-1 in the Holmberg II galaxy, the quadruple gravitational lens system Q2237+0305 (the "Einstein Cross"), the Galactic planetary nebula NGC7027, and extragalactic planetary nebulae in M31. PMAS is now available as a common user instrument at Calar Alto Observatory.Comment: 4 pages, 9 figures (attached in JPEG format), Euro3D Science Workshop Proceedings, held in Cambridge May 21-23, 2003, to appear in AN (accepted

Stable marriage and roommates problems with restricted edges: complexity and approximability

In the Stable Marriage and Roommates problems, a set of agents is given, each of them having a strictly ordered preference list over some or all of the other agents. A matching is a set of disjoint pairs of mutually acceptable agents. If any two agents mutually prefer each other to their partner, then they block the matching, otherwise, the matching is said to be stable. We investigate the complexity of finding a solution satisfying additional constraints on restricted pairs of agents. Restricted pairs can be either forced or forbidden. A stable solution must contain all of the forced pairs, while it must contain none of the forbidden pairs. Dias et al. (2003) gave a polynomial-time algorithm to decide whether such a solution exists in the presence of restricted edges. If the answer is no, one might look for a solution close to optimal. Since optimality in this context means that the matching is stable and satisfies all constraints on restricted pairs, there are two ways of relaxing the constraints by permitting a solution to: (1) be blocked by as few as possible pairs, or (2) violate as few as possible constraints n restricted pairs. Our main theorems prove that for the (bipartite) Stable Marriage problem, case (1) leads to View the MathML source-hardness and inapproximability results, whilst case (2) can be solved in polynomial time. For non-bipartite Stable Roommates instances, case (2) yields an View the MathML source-hard but (under some cardinality assumptions) 2-approximable problem. In the case of View the MathML source-hard problems, we also discuss polynomially solvable special cases, arising from restrictions on the lengths of the preference lists, or upper bounds on the numbers of restricted pairs

Time Data Sequential Processor /TDSP/

Time Data Sequential Processor /TDSP/ computer program provides preflight predictions for lunar trajectories from injection to impact, and for planetary escape trajectories for up to 100 hours from launch. One of the major options TDSP performs is the determination of tracking station view periods

Control networks for the Galilean satellites, November 1979

Pictures of the four Galilean satellites taken as the two Voyager spacecraft approached Jupiter during March and July 1979 are presented. Control nets of the Galilean satellites, computed photogrammetrically, and measurements of the mean radii are presented. The pictures in the control nets are identified, the coordinates of the control points are given, and identifications of some of the control points are shown on figures. The use of star field pictures to compute the focal lengths of the camera is discussed and the geometric relationship between the narrow and wide and angle cameras is reported. A description of the coordinate systems of the Galilean satellites is presented and the status of the control net computations is reported

An Analytical Approach of Modelling Friction Stir Welding

AbstractA simple model for torque in friction stir welding is developed, based on a sliding/sticking condition in the contact interface, correlating the fundamental response variables temperature and axial force to torque. The model is validated by experiments using a special test rig enabling the precise measurement of the response variables. From the measured torque and axial force the friction coefficient μf is calculated and analyzed. It is observed that μf increases with decreasing rotation speed and drops with abrupt step-ups of the plunge depth. μf is found to mainly vary in the range of 0.3-0.4

Integer programming methods for special college admissions problems

We develop Integer Programming (IP) solutions for some special college admission problems arising from the Hungarian higher education admission scheme. We focus on four special features, namely the solution concept of stable score-limits, the presence of lower and common quotas, and paired applications. We note that each of the latter three special feature makes the college admissions problem NP-hard to solve. Currently, a heuristic based on the Gale-Shapley algorithm is being used in the application. The IP methods that we propose are not only interesting theoretically, but may also serve as an alternative solution concept for this practical application, and also for other ones