Dual band combiner for horn antenna

A corrugated horn antenna, adapted to be coupled to a waveguide at its apex for X-band excitation is further adapted to be connected to waveguides through a circumferential slot for S-band excitation at four distinct phases selected for the desired S-band polarization. The circumferential slot is positioned along the axial length of the horn for good impedance matching and is provided with an X-band choke in the form of two concentric choke slots. For further improvement in impedance matching, the second (outer) choke slot is divided by plugs into four segments that coincide with waveguide ports for the four distinct phases of the S-band

Manufacturing Metallic Parts with Designed Mesostructure via Three-Dimensional Printing of Metal Oxide Powder

Cellular materials, metallic bodies with gaseous voids, are a promising class of materials that offer high strength accompanied by a relatively low mass. In this paper, the authors investigate the use of ThreeDimensional Printing (3DP) to manufacture metallic cellular materials by selectively printing binder into a bed of metal oxide ceramic powder. The resulting green part undergoes a thermal chemical post-process in order to convert it to metal. As a result of their investigation, the authors are able to create cellular materials made of maraging steel that feature wall sizes as small as 400 µm and angled trusses and channels that are 1 mm in diameter.Mechanical Engineerin

Nonparametric Regression using the Concept of Minimum Energy

It has recently been shown that an unbinned distance-based statistic, the energy, can be used to construct an extremely powerful nonparametric multivariate two sample goodness-of-fit test. An extension to this method that makes it possible to perform nonparametric regression using multiple multivariate data sets is presented in this paper. The technique, which is based on the concept of minimizing the energy of the system, permits determination of parameters of interest without the need for parametric expressions of the parent distributions of the data sets. The application and performance of this new method is discussed in the context of some simple example analyses.Comment: 10 pages, 4 figure

Cooling system for removing metabolic heat from an hermetically sealed spacesuit

An improved cooling and ventilating system is described for removing metabolic heat, waste gases and water vapor generated by a wearer of an hermetically sealed spacesuit. The cooling system was characterized by a body suit, having a first circuit for simultaneously establishing a cooling flow of water through the thorax and head sections of the body suit. Circulation patches were included mounted in the thorax section and head section of the body suit. A second circuit for discharing a flow of gas throughout the spacesuit and a disconnect unit for coupling the circuits with a life support system externally related to the spacesuit were provided

Liquid-cooled liner for helmets

Liner acts as coolant tubing, manifold, and supporting structures. Fabric of waffle-design is made of several integrated channels (or capillaries) through which coolant liquid can flow. Thin and light-weight liner can be incorporated into any type of helmet or head gear

Chlorinated Hydrocarbons in Marine Female Fishes of Lagos Lagoon

Three female fish species of Snapper (Lutjanus goreensis), Herring (Sardinella maderensis) and Oarfish (Regalecus glesne) were sampled from Lagos Lagoon during the dry and wet seasons of 2008 and 2009 and subjected to cold extraction and clean-up procedure. Their muscle tissues were analysed for chlorinated hydrocarbons because they can concen trate pesticide residues from sediments and water. The identification and quantitation of the chlorinated hydrocarbon residues were performed using a gas chromatograph with a 63 Ni electron capture detector. The fishes had condition factor of more than 1 except Regalecus glesne. A higher concentration of the residues was observed during the dry season. The residue distribution pattern in muscle tissues of the fishes were: Regalecus glesne > Sardinella maderensis > Lutjanus goreensis. Regalecus glesne recorded the highest chlorinated hydrocarbon content: 6181.16 ng/g. Except for endrin and heptachlor, the estimated daily intakes of the organochlorines were within the acceptable daily intakes while the levels of residues in the fishes were within the permissible residue limits

An Exact Solution for the Lattice Gas Model in One Dimension

A simple method to obtain a canonical partition function for one dimensional lattice gas model is presented. The simplification is based upon rewriting a sum over all possible configurations to a sum over numbers of clusters in the system.Comment: 6 pages, LaTe

FLIC Overlap Fermions

The action of the overlap-Dirac operator on a vector is typically implemented indirectly through a multi-shift conjugate gradient solver. The compute-time required depends upon the condition number, $\kappa$, of the matrix that is used as the overlap kernel. While the Wilson action is typically used as the overlap kernel, the FLIC (Fat Link Irrelevant Clover) action has an improved condition number and provides up to a factor of two speedup in evaluating the overlap action. We summarize recent progress on the use of FLIC overlap fermions.Comment: Lattice2002(chiral

Resonant Few-Photon Excitation of a Single-Ion Oscillator

We study the motion of an undamped single-ion harmonic oscillator, resonantly driven with a pulsed radiation pressure force. We demonstrate that a barium ion, initially cooled to the Doppler limit, quickly phase locks to the drive and builds up coherent oscillations above the thermal distribution after scattering of order one hundred photons. In our experiment, this seeded motion is subsequently amplified and then analyzed by Doppler velocimetry. Since the coherent oscillation is conditional upon the internal quantum state of the ion, this motional excitation technique could be useful in atomic or molecular single-ion spectroscopy experiments, providing a simple protocol for state readout of non-fluorescing ions with partially closed-cycle transitions

Application of quasi-homogeneous anisotropic laminates in grid-stiffened panel design

Composite laminates are derived for standard configurations with quasi-homogeneous anisotropic properties, whereby in-plane and out-of-plane stiffness properties are concomitant. Dimensionless parameters, and their relationship to the well-known ply- orientation-dependent lamination parameters, are also developed from which the elements of the extensional and bending stiffness matrices are readily calculated for any fiber/resin properties. The definitive list of laminate configurations for up to 21 plies is presented, together with graphical representations of the lamination parameter design space for standard ply orientations +45, -45, 0 and 90 degrees. Finally, the potential of quasi-homogeneous anisotropic laminates as an optimum design solution for anisogid structures is explored for cases where buckling and strength constraints are both active