Approximate and exact numerical integration of the gas dynamic equations

A highly accurate approximation and a rapidly convergent numerical procedure are developed for two dimensional steady supersonic flow over an airfoil. Examples are given for a symmetric airfoil over a range of Mach numbers. Several interesting features are found in the calculation of the tail shock and the flow behind the airfoil

Super-rotating jets in a re-analysis of the martian atmosphere

Strong westerly, prograde jets have been identified in the martian atmosphere between about 10–20 km altitude throughout much of the year in a Mars Global Circulation Model (MGCM) study [2]. The development of data assimilation techniques for Mars [3, 5] now permits the analysis of super-rotation in less highly idealized cases using an atmospheric reanalysis, as would be done for the Earth. This paper reviews recent atmospheric reanalyses, in order to validate previous modeling results, to quantify jet amplitudes and to diagnose possible mechanisms supplying angular momentum to the jets. [2] Lewis, S. R., and Read, P. L.: Equatorial jets in the dusty martian atmosphere, J. Geophys. Res., Vol. 108 (E4), 5034, pp. 1–15, 2003. [3] Lewis, S. R., Read, P. L., Conrath, B. J., Pearl, J. C., and Smith, M. D.: Assimilation of Thermal Emission Spectrometer atmospheric data during the Mars Global Surveyor aerobraking period, Icarus, Vol. 192 (2), pp. 327–347, 2007. [5] Montabone, L., Lewis, S. R., Read, P. L., Hinson, D. P., Validation of Martian meteorological data assimilation for MGS/TES using radio occultation measurements, Icarus Vol. 185 (1), pp. 113–132, 2006

Normalizing connections and the energy-momentum method

The block diagonalization method for determining the stability of relative equilibria is discussed from the point of view of connections. We construct connections whose horizontal and vertical decompositions simultaneosly put the second variation of the augmented Hamiltonian and the symplectic structure into normal form. The cotangent bundle reduction theorem provides the setting in which the results are obtained

New X-ray Clusters in the EMSS II: Optical Properties

We present optical images for 9 new clusters of galaxies we have found in a reanalysis of the Einstein IPC images comprising the Extended Medium Sensitivity Survey (EMSS). Based on the presence of a red sequence of galaxies in a color-magnitude (CM) diagram, a redshift is estimated for each cluster. Galaxy overdensities (cluster richnesses) are measured in each field using the B_gc statistic which allows their plausible identification with the X-ray emission. The nature of our X-ray detection algorithm suggests that most of these clusters have low X-ray surface brightness (LSB) compared to the previously known EMSS clusters. We compare the optical and X-ray observations of these clusters with the well-studied Canadian Network for Observational Cosmology (CNOC) subsample of the EMSS, and conclude that the new clusters exhibit a similar range of optical richnesses, X-ray luminosities, and, somewhat surprisingly, galaxy populations as the predominantly rich, relaxed EMSS/CNOC clusters.Comment: Accepted to ApJ, 17 pages, 14 figures, uses emulateapj5.st

Fast moving of a population of robots through a complex scenario

Swarm robotics consists in using a large number of coordinated autonomous robots, or agents, to accomplish one or more tasks, using local and/or global rules. Individual and collective objectives can be designed for each robot of the swarm. Generally, the agents' interactions exhibit a high degree of complexity that makes it impossible to skip nonlinearities in the model. In this paper, is implemented both a collective interaction using a modified Vicsek model where each agent follows a local group velocity and the individual interaction concerning internal and external obstacle avoidance. The proposed strategies are tested for the migration of a unicycle robot swarm in an unknown environment, where the effectiveness and the migration time are analyzed. To this aim, a new optimal control method for nonlinear dynamical systems and cost functions, named Feedback Local Optimality Principle - FLOP, is applied

Development of a reconfigurable protective system for multi-rotor UAS

The purpose of this study is to illustrate how the design and deployment of a minimal protective system for multi-rotorcraft can cater for changes in legislation and provide for greater use both in and outdoors. A methodology is presented to evaluate the design and development of a system which protects both single axial and co-axial rotorcraft. The key emphasis of the development presented is the scenario in which the multi-rotorcraft can fly with increased speed including the capability of flying through windows and doors without the fear of system failure due to rotor disruption. Discussed as well is the degree of autonomy the reconfigurable system should feature as well as the effects of drag and added component mass to the performance of the system