CFAR behavior of adaptive detectors: an experimental analysis

We conduct an experimental analysis for assessing the constant false alarm rate (CFAR) behavior of four coherent adaptive radar detectors in the presence of experimentally measured clutter data. To this end we exploit several data files containing both land, lake, and mixed land and sea clutter, collected by two radar systems (the MIT Lincoln Laboratory Phase-One radar and the McMaster IPIX radar) at different polarizations, range resolutions, and frequency bands. The results show that all the receivers, in the presence of real data, don't respect their nominal probability of false alarm (P/sub fa/), namely they exhibit a false alarm rate higher than the value preassigned at the design stage. Nevertheless one of them, the recursive persymmetric adaptive normalized matched filter (RP-ANMF) is very robust, in the sense that it presents an acceptable displacement from the nominal P/sub fa/, in correspondence of all the analyzed scenarios.     

The THEMIS Digital Fields Board

The Digital Fields Board (DFB) performs the data acquisition and signal processing for the Electric Fields Instrument and Search Coil Magnetometer on each of the THEMIS (Time History of Events and Macroscale Interactions during Substorms) satellites. The processing is highly flexible and low-power (～1.1 watt orbit-averaged). The primary data products are time series waveforms and wave power spectra of the electric and magnetic fields. The power spectra can be computed either on the raw signals (i.e. in a system co-rotating with the spacecraft) or in a coordinate system aligned with the local DC magnetic field. Other data products include spectral power from multiple passbands (filter banks) and electric power in the 30–500 kHz band. The DFBs on all five spacecraft have been turned on and checked out in-flight, and are functioning as designed.     

Model of effective heat conduction in polymer composite porous materials

A model and a technique for calculating polymer composite materials with an ellipsoid-shaped filler that take into account the influence of system porosity, particle anisodiametry and a boundary layer on the effective heat conduction are proposed. The results of calculations made by numerical methods are in a good agreement with the well-known statistic and Odolevskii, Maxwell, and Dul’nev matrix models.     

Exact solution of a problem on heat exchange in channels under unsteady conditions at low biot number values

A number of exact solutions of a problem on heat exchange in channels under unsteady conditions at the low Biot numbers and sufficiently low Brune numbers with and without consideration for a heat carrier stay period in a pipeline are obtained.     

International scientific optical network for space debris research

A joint team of researchers under the auspices of the Center for Space Debris Information Collection, Processing and Analysis of the Russian Academy of Sciences collaborates with 15 observatories around the world to perform observations of space debris. For this purpose, 14 telescopes were equipped with charge-coupled device (CCD) cameras, Global Positioning System (GPS) receivers, CCD frame processing and ephemeris computation software, with the support of the European and Russian grants. Many of the observation campaigns were carried out in collaboration with the Astronomical Institute of the University of Bern (AIUB) team operating at the Zimmerwald observatory and conducting research for the European Space Agency (ESA), using the Tenerife/Teide telescope for searching and tracking of unknown objects in the geostationary region (GEO). More than 130,000 measurements of space objects along a GEO arc of 340.9°, collected and processed at Space Debris Data Base in the Ballistic Center of the Keldysh Institute of Applied Mathematics (KIAM) in 2005–2006, allowed us to find 288 GEO objects that are absent in the public orbital databases and to determine their orbital elements. Methods of discovering and tracking small space debris fragments at high orbits were developed and tested. About 40 of 150 detected unknown objects of magnitudes 15–20.5 were tracked during many months. A series of dedicated 22-cm telescopes with large field of view for GEO survey tasks is in process of construction. 7 60-cm telescopes will be modernized in 2007.     

Whistler waves in plasmas with time-varying magnetic field: Laboratory investigation

Modulation of whistler waves in a plasma with time-dependant magnetic field perturbations was investigated experimentally. The experiments were performed on large “Krot” device, which was specially designed to study space plasma physics phenomena. It is shown that magnetic field variations on the wave propagation path can lead to splitting of initially continuous whistler wave into the sequence of bursts, whose repetition rate corresponds to magnetic field perturbation period. The frequency inside each burst is changing from its front edge to the back edge. Relative shift of the wave frequency can be as large as the relative magnetic disturbance. Distortion of whistler wave frequency spectrum after its passing through magnetically disturbed areas can be used as a diagnostics for low-frequency magnetic field variations. The applicability of our laboratory results to space plasma is discussed.     

Italian polar data center for capacity building associated with the IHY

The International Heliophysical Year offers a good opportunity to develop and coordinate studies on the Sun–Earth system by using a large variety of simultaneous data obtained by satellite/spacecraft and ground based instruments. Among these data we recall the ones coming from solar and interplanetary medium observations, auroral, neutron monitor, geomagnetic field, ionospheric, meteorological, and other atmospheric observatories. In this context, an Information System for the Italian Research in Antarctica has started in 2003, aiming to collect information on the scientific research projects funded by the National Antarctic Research Program of Italy since its establishment (1985). It belongs to Joint Committee on Antarctic Data Management of Scientific Committee on Antarctic Research as Italian Antarctic Data Center. This project, as the Italian Polar Database, gathers also information on research activities conducted in North Pole regions. This Information System can be a relevant resource for capacity building associated with the International Heliophysical Year, especially for people involved in interdisciplinary researches. We describe the present status of the Italian Polar Data Center and its potential use.     

Genetic susceptibility to radiation.

In the context of space radiation, it is important to know whether the human population includes genetically predisposed radiosensitive subsets. One possibility is that haploinsufficiency for ATM confers radiosensitivity, and this defect involves 1-3% of the population. Using knock-out mice we chose to study cataractogenesis in the lens and oncogenic transformation in mouse embryo fibroblasts to assay for effects of ATM deficiency. Radiation induced cataracts appeared earlier in the heterozygous versus wild-type animals following exposure to either gamma rays or 1 GeV/nucleon iron ions. In addition, it was found that embryo fibroblasts of Atm heterozygotes showed an increased incidence of oncogenic transformation compared with their normal litter-matched counterparts. From these data we suggest that Ataxia Telangiectasia heterozygotes could indeed represent a societally significant radio sensitive subpopulation. Knock-out mice are now available for other genes including BRCA1 and 2, and Mrad9. An exciting possibility is the creation of double heterozygotes for pairs of mutated genes that function in the same signal transduction pathway, and consequently confer even greater radiosensitivity.     

A parametric study of space radiation exposures to critical body organs for low earth orbit missions.

The geomagnetically-trapped and galactic cosmic radiation environments are two of the major sources of naturally-occurring space radiation exposure to astronauts in low earth orbit. The exposure is dependent primarily on altitude, spacecraft shielding, crew stay-times, and solar cycle effects for a 28.5 deg orbital inclination. Based on Space Shuttle experience, the calculated results of a parametric study are presented for several mission scenarios using a computerized anatomical man model and are compared with the NASA crew exposure limits for several critical body organs.