Application of trajectory optimization techniques to upper atmosphere sampling flights using the F-15 Eagle aircraft

Atmospheric sampling has been carried out by flights using an available high-performance supersonic aircraft. Altitude potential of an off-the-shelf F-15 aircraft is examined. It is shown that the standard F-15 has a maximum altitude capability in excess of 100,000 feet for routine flight operation by NASA personnel. This altitude is well in excess of the minimum altitudes which must be achieved for monitoring the possible growth of suspected aerosol contaminants

Application of trajectory optimization techniques to upper atmosphere sampling flights using the F4-C Phantom aircraft

Altitude potential of an off-the-shelf F4-C aircraft is examined. It is shown that the standard F4-C has a maximum altitude capability in the region from 85000 to 95000 ft, depending on the minimum dynamic pressures deemed acceptable for adequate flight control. By using engine overspeed capability and by making use of prevailing winds in the stratosphere, it is suggested that the maximum altitude achievable by an F4-C should be in the vicinity of 95000 ft for routine flight operation. This altitude is well in excess of the minimum altitudes which must be achieved for monitoring the possible growth of suspected aerosol contaminants

Human Capital Investments in Children: A Comparative Analysis of the Role of Parent-Child Shared Time in Selected Countries

Parents invest in their children's human capital in several ways. We investigate the extent to which the levels and composition of parent-child time varies across countries with different welfare regimes: Finland, Germany and the United States. We test the hypothesis of parent-child time as a form of human capital investment in children using a propensity score treatment effects approach that accounts for the possible endogenous nature of time use and human capital investment. Result: There is considerable evidence of welfare regime effects on parent-child shared time. Our results provide mixed support for the hypothesis that non-care related parent-child time is human capital enriching. The strongest support is found in the case of leisure time and eating time.parent-child time, comparative research, welfare regimes, Finland, Germany, USA, treatment effects, propensity score matching

A differential game solution to the Coplanar tail-chase aerial combat problem

Numerical results obtained in a simplified version of the one on one aerial combat problem are presented. The primary aim of the data is to specify the roles of pursuer and evader as functions of the relative geometry and of the significant physical parameters of the problem. Numerical results are given in a case in which the slower aircraft is more maneuverable than the faster aircraft. A third order dynamic model of the relative motion is described, for which the state variables are relative range, bearing, and heading. The ranges at termination are arbitary in the present version of the problem, so the weapon systems of both aircraft can be visualized as forward firing high velocity weapons, which must be aimed at the tail pipe of the evader. It was found that, for the great majority of the ralative geometries, each aircraft can evade the weapon system of the other

Combinatorial Optimization by Iterative Partial Transcription

A procedure is presented which considerably improves the performance of local search based heuristic algorithms for combinatorial optimization problems. It increases the average `gain' of the individual local searches by merging pairs of solutions: certain parts of either solution are transcribed by the related parts of the respective other solution, corresponding to flipping clusters of a spin glass. This iterative partial transcription acts as a local search in the subspace spanned by the differing components of both solutions. Embedding it in the simple multi-start-local-search algorithm and in the thermal-cycling method, we demonstrate its effectiveness for several instances of the traveling salesman problem. The obtained results indicate that, for this task, such approaches are far superior to simulated annealing.Comment: RevTex-file: 18 pages, 3 Postscript figures. Accepted for publication in Phys. Rev.

High Performance P3M N-body code: CUBEP3M

This paper presents CUBEP3M, a publicly-available high performance cosmological N-body code and describes many utilities and extensions that have been added to the standard package. These include a memory-light runtime SO halo finder, a non-Gaussian initial conditions generator, and a system of unique particle identification. CUBEP3M is fast, its accuracy is tuneable to optimize speed or memory, and has been run on more than 27,000 cores, achieving within a factor of two of ideal weak scaling even at this problem size. The code can be run in an extra-lean mode where the peak memory imprint for large runs is as low as 37 bytes per particles, which is almost two times leaner than other widely used N-body codes. However, load imbalances can increase this requirement by a factor of two, such that fast configurations with all the utilities enabled and load imbalances factored in require between 70 and 120 bytes per particles. CUBEP3M is well designed to study large scales cosmological systems, where imbalances are not too large and adaptive time-stepping not essential. It has already been used for a broad number of science applications that require either large samples of non-linear realizations or very large dark matter N-body simulations, including cosmological reionization, halo formation, baryonic acoustic oscillations, weak lensing or non-Gaussian statistics. We discuss the structure, the accuracy, known systematic effects and the scaling performance of the code and its utilities, when applicable.Comment: 20 pages, 17 figures, added halo profiles, updated to match MNRAS accepted versio

Human capital investments in children: A comparative analysis of the role of parent-child shared time in selected countries

Parents invest in their children's human capital in several ways. We investigate the extent to which the levels and composition of parent-child time varies across countries with different welfare regimes: Finland, Germany and the United States. We test the hypothesis of parentchild time as a form of human capital investment in children using a propensity score treatment effects approach that accounts for the possible endogenous nature of time use and human capital investment. Result: There is considerable evidence of welfare regime effects on parent-child shared time. Our results provide mixed support for the hypothesis that noncare related parent-child time is human capital enriching. The strongest support is found in the case of leisure time and eating time

Hysteresis in an Ising model with mobile bonds

Hysteresis is studied in a disordered Ising model in which diffusion of antiferromagnetic bonds is allowed in addition to spin flips. Saturation behavior changes to a figure-eight loop when diffusion is introduced. The upper and lower fields delimiting the figure-eight are determined by the Hamiltonian, while its surface and the crossing point depend on the temperature and details of the dynamics. The main avalanche is associated with the disappearance of hidden order. Some experimental observations of figure-eight anomalies are discussed. It is argued they are a signal of a transient rearrangement of domain couplings, characteristic of amorphous and/or magnetically soft samples, and similar to evolution of kinetic glasses.Comment: 7 pages, 7 figure

Human capital investments in children: A comparative analysis of the role of parent-child shared time in selected countries

Parents invest in their children's human capital in several ways. We investigate the extent to which the levels and composition of parent-child time varies across countries with different welfare regimes: Finland, Germany and the United States. We test the hypothesis of parentchild time as a form of human capital investment in children using a propensity score treatment effects approach that accounts for the possible endogenous nature of time use and human capital investment. Result: There is considerable evidence of welfare regime effects on parent-child shared time. Our results provide mixed support for the hypothesis that non-care related parent-child time is human capital enriching. The strongest support is found in the case of leisure time and eating time.Eltern investieren in ihre Kinder auf unterschiedliche Weise. Wir untersuchen wie das Ausmaß und die Zusammensetzung von Eltern-Kind Zeiten in unterschiedlichen Ländern mit differenten Wohlfahrtsregimes variiert: Finnland, Deutschland und die Vereinigten Staaten von Amerika. Komposition: Wir testen die Hypothese der Eltern-Kind Zeiten als eine Form von Humankapitalinvestitionen in Kinder mit einem 'propensity score treatment effects'-Ansatz für die mögliche Endogenität der Zeitverwendung und Humankapitalinvestition. Resultat: Wohlfahrtsregime haben einen signifikanten Einfluss auf die von Eltern mit ihren Kindern verbrachte Zeit. Unsere Resultate unterstützen die Hypothese, dass Eltern-Kind Zeiten, die nicht als Kinderbetreuung zu charakterisieren sind, Humankapital anreichern. Die stärkste Unterstützung wurde für die Bereiche Freizeit und gemeinsam verbrachte Essenszeiten gefunden