Performance Analysis and Design of Maximum Ratio Combining in Channel-Aware MIMO Decision Fusion

In this paper we present a theoretical performance analysis of the maximum ratio combining (MRC) rule for channel-aware decision fusion over multiple-input multiple-output (MIMO) channels for (conditionally) dependent and independent local decisions. The system probabilities of false alarm and detection conditioned on the channel realization are derived in closed form and an approximated threshold choice is given. Furthermore, the channel-averaged (CA) performances are evaluated in terms of the CA system probabilities of false alarm and detection and the area under the receiver operating characteristic (ROC) through the closed form of the conditional moment generating function (MGF) of the MRC statistic, along with Gauss-Chebyshev (GC) quadrature rules. Furthermore, we derive the deflection coefficients in closed form, which are used for sensor threshold design. Finally, all the results are confirmed through Monte Carlo simulations.Comment: To appear in IEEE Transactions on Wireless Communication

Shape maps for second order partial differential equations

We analyse the singularity formation of congruences of solutions of systems of second order PDEs via the construction of \emph{shape maps}. The trace of such maps represents a congruence volume whose collapse we study through an appropriate evolution equation, akin to Raychaudhuri's equation. We develop the necessary geometric framework on a suitable jet space in which the shape maps appear naturally associated with certain linear connections. Explicit computations are given, along with a nontrivial example

Innovative methods of correlation and orbit determination for space debris

We propose two algorithms to provide a full preliminary orbit of an Earth-orbiting object with a number of observations lower than the classical methods, such as those by Laplace and Gauss. The first one is the Virtual debris algorithm, based upon the admissible region, that is the set of the unknown quantities corresponding to possible orbits for objects in Earth orbit (as opposed to both interplanetary orbits and ballistic ones). A similar method has already been successfully used in recent years for the asteroidal case. The second algorithm uses the integrals of the geocentric 2-body motion, which must have the same values at the times of the different observations for a common orbit to exist. We also discuss how to account for the perturbations of the 2-body motion, e.g., the $J_2$ effect.Comment: 18 page

Charge Detection in Phosphorus-doped Silicon Double Quantum Dots

We report charge detection in degenerately phosphorus-doped silicon double quantum dots (DQD) electrically connected to an electron reservoir. The sensing device is a single electron transistor (SET) patterned in close proximity to the DQD. Measurements performed at 4.2K show step-like behaviour and shifts of the Coulomb Blockade oscillations in the detector's current as the reservoir's potential is swept. By means of a classical capacitance model, we demonstrate that the observed features can be used to detect single-electron tunnelling from, to and within the DQD, as well as to reveal the DQD charge occupancy.Comment: 4 pages, 3 figure

Mars Observer Radar Altimeter Radiometer (MORAR)

The Mars Observer Project will permit the advancement of the state of the topographic and hypsometric knowledge of Mars to a level of 10 m or better over the surface of the planet Mars, the measurement of microwave surface brightness temperature of Mars with an accuracy of 15 to 20 K over 24 hours, and the measurement, globally, of surface returned power related to radar cross section with an accuracy of 1 dB and a repeatability of .5 dB. The MORAR Hardware Development, Ground Data Processing, and the Mission Operations will allow the accomplishment of these scientific objectives to define globally the topography of Mars at sufficient vertical resolution and spatial scale to address both large-scale geophysical and small-scale geologic problems, and to obtain global surface electrical and scattering properties of the upper several centimeters of the Martian surface for assessment of the composition, physical state, and volatile distribution of the surface

Identification of Showers with Cores Outside the ARGO-YBJ Detector

In any EAS array, the rejection of events with shower cores outside the detector boundaries is of great importance. A large difference between the true and the reconstructed shower core positions may lead to a systematic miscalculation of some shower characteristics. Moreover, an accurate determination of the shower core position for selected internal events is important to reconstruct the primary direction using conical fits to the shower front, improving the detector angular resolution, or to performe an efficient gamma/hadron discrimination. In this paper we present a procedure able to identify and reject showers with cores outside the ARGO-YBJ carpet boundaries. A comparison of the results for gamma and proton induced showers is reported.Comment: 4 pages, to be published in the Proceedings of the 28th International Cosmic Ray Conference (Tsukuba, Japan 2003