A Solenoidal Finite Element Approach for Prediction of Radar Cross Sections

This report considers the solution of problems that involve the scattering of plane electromagnetic waves by perfectly conducting obstacles. Such problems are governed by the Maxwell equations. An interesting facet of the solution of Faraday's law and Ampere's law, which on their own form a complete equation set for the determination of the field intensity components, is that there are the additional conservation statements of Coulomb's law and Gauss's law, which appear to be in excess of requirements. Often, these additional constraints are neglected due to an inability to incorporate them into the solution scheme. With the successful development of a solenoidal finite element for the solution of viscous incompressible flows, such a device now offers a practical means for the solution of the full Maxwell equations. To demonstrate the validity of this assertion, a suitable solution scheme is presented, accompanied by sample results for various test problems

Simulation capability for dynamics of two-body flexible satellites

An analysis and computer program were prepared to realistically simulate the dynamic behavior of a class of satellites consisting of two end bodies separated by a connecting structure. The shape and mass distribution of the flexible end bodies are arbitrary; the connecting structure is flexible but massless and is capable of deployment and retraction. Fluid flowing in a piping system and rigid moving masses, representing a cargo elevator or crew members, have been modeled. Connecting structure characteristics, control systems, and externally applied loads are modeled in easily replaced subroutines. Subroutines currently available include a telescopic beam-type connecting structure as well as attitude, deployment, spin and wobble control. In addition, a unique mass balance control system was developed to sense and balance mass shifts due to the motion of a cargo elevator. The mass of the cargo may vary through a large range. Numerical results are discussed for various types of runs

Water separator

An apparatus for separating liquids from gases or gaseous fluids is described. Features of the apparatus include: (1) the collection and removal of the moisture in the fluid is not dependent upon, or affected by gravity; (2) all the collected water is cyclically drained from the apparatus irrespective of the attitude of the separator; and (3) a fluid actuator is utilized to remove the collected water from the separator

Tensor Spectral Clustering for Partitioning Higher-order Network Structures

Spectral graph theory-based methods represent an important class of tools for studying the structure of networks. Spectral methods are based on a first-order Markov chain derived from a random walk on the graph and thus they cannot take advantage of important higher-order network substructures such as triangles, cycles, and feed-forward loops. Here we propose a Tensor Spectral Clustering (TSC) algorithm that allows for modeling higher-order network structures in a graph partitioning framework. Our TSC algorithm allows the user to specify which higher-order network structures (cycles, feed-forward loops, etc.) should be preserved by the network clustering. Higher-order network structures of interest are represented using a tensor, which we then partition by developing a multilinear spectral method. Our framework can be applied to discovering layered flows in networks as well as graph anomaly detection, which we illustrate on synthetic networks. In directed networks, a higher-order structure of particular interest is the directed 3-cycle, which captures feedback loops in networks. We demonstrate that our TSC algorithm produces large partitions that cut fewer directed 3-cycles than standard spectral clustering algorithms.Comment: SDM 201

RTCC requirements for mission G - Landing site determination using onboard observations, part 2 Final report

Computer programs for evaluation of telemetered rendezvous radar tracking data of orbiting command module and lunar module landing site determinatio