The role of nonlocalities in magnetosphere-ionosphere coupling processes

Microinstabilities are believed to play a crucial role in the physics of Magnetosphere-Ionosphere coupling. The current driven ion cyclotron instability is a very important microinstability in this respect. We give a nonlocal formalism for studying the ion cyclotron instability in a more realistic magnetospheric environment than is available in the widely used local theory. This formalism includes the magnetic shear produced self-consistently by the field aligned currents and the finite extent of such currents. Significant departures from the local theory are noted.     

Reduction of aliasing ambiguities through phase relations

A method for digital determination of a single frequency from a sine wave sampled at less than the Nyquist rate is discussed. The method makes use of phase shift information to eliminate the aliasing ambiguity. Multiple sampled data are required to eliminate ambiguity completely. Computer modeling using simulated data corrupted by uncorrelated Gaussian noise was used to verify the approach. The results demonstrate that the frequency of an input sine wave can be correctly identified. This approach can be applied to electronic warfare (EW) receivers to increase their input bandwidth     

Wind Oscillatory and Gusting Torque Effect on a Power System

The dynamics of a wind turbine driven induction machine and the power system to which it is connected in a dispersed mode are described. The sources of disturbances are identified as ramp and low frequency cyclic turbine torque variations as a consequence of sharp fronted wind gusts and tower shadow, rotor unbalance, etc. Studies have been performed for two levels of wind energy penetration in a single area power system and in a multiarea interconnected power system. Results show that substantial wind energy penetration levels can be handled in a multiarea power system.     

An overview of Allied-Signal's avionics development in the CIS

AlliedSignal Commercial Avionics Systems (ASCAS) and its partners have established the following business objectives: short term (forward-fit and retrofit with off-the-shelf products; co-development of integrated systems); mid term (co-production of avionics products in the CIS); long term (become an integrated element of CIS aerospace industry in partnership with local firms and to maintain the necessary focus to achieve these goals). ASCAS has formed a strategic business enterprise which is dedicated to developing the avionics market within the CIS. ASCAS was fortunate to find a joint venture partner who possesses skills that complement its present core competencies. The advantage of this business arrangement is that, while expanding their experience and expertise in the area of systems integration, they can directly benefit from the expertise and capabilities of indigenous airframe and equipment manufacturers (customer knowledge, simulation and integration experience, capable/skilled manpower)     

A visionary look at aviation surveillance systems

The FAA's future aviation surveillance systems fall into four categories: Automatic Dependent Surveillance (ADS) will be used in the oceanic environment; ADS-Broadcast (ADS-B) will be used in the domestic en route environment; ADS-B will be used with a secondary radar backup in the terminal area; and ADS-B will be used with primary radar backup within the Airport Surface Traffic Automation (ASTA) system on the airport's surface environment. Two other systems introduced in this paper are Cockpit Display of Traffic Information (CDTI) and Traffic Advisory and Collision Avoidance System (TCAS). All these systems will use navigational signals emitted by the Global Positioning System (GPS) constellation of satellites     

Sharp Boundaries of Solar Wind Plasma Structures and an Analysis of Their Pressure Balance

This work is devoted to studying the sharp boundaries of small-scale structures of the solar wind according to the data of measurements with high time resolution onboard the INTERBALL-1 satellite and simultaneous measurements of the WIND spacecraft. Such issues as the character of change of various plasma and magnetic field parameters on these boundaries, the duration of boundary passage and the balance of the total (thermal plus magnetic) pressure on the boundaries of the structures are considered. On the basis of the vast statistical material available, the typical conditions in the solar wind are investigated, in which such sharp boundaries are observed.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 3, 2005, pp. 163–170.Original Russian Text Copyright © 2005 by Riazantseva, Khabarova, Zastenker, Richardson.     

Novel hybrid 12-pulse boost-type rectifier with controlled output voltage

Novel hybrid 12-pulse line interphase transformer (LIT) rectifier systems with integrated single-switch or two-switch boost-type output stage that ensure a constant output voltage independent of mains and load conditions are proposed for supplying actuators of future more electric aircraft. The principle of operation, the dimensioning, and the system control are discussed. The theoretical considerations are experimentally confirmed for a 10 kW laboratory prototype. Finally, the single-and the two-switch system are comparatively evaluated concerning the level of input current ripple, power factor, and overall efficiency.     

Is there a single origin of life?

The emergence of the first life on the earth is now established as an early event, and closely related to the evolving earth. Laboratory experiments examining possible chemical events have revealed a multitude of plausible pathways. Lack of knowledge of the primitive terrestrial conditions contemporary with the evolving prebolic organic chemistry limits reconstruction techniques. The primitive earth's aqueous history is essential to unraveling this problem. Based on our current knowledge of other planets of the solar system, we do not expect close analogues to the early earth. We still do not know if there was a second origin or if only earth has life. This may depend upon the question of the survival of information bearing chemical systems in a dynamic or chaotic environment and the chemical protection afforded within such a system. Water is the central molecule of controversy: the blessing and the curse of the chemist. New and novel chemical mechanisms and systems abound.     

Low observable target motion analysis using amplitude information

In conventional passive and active sonar system, target amplitude information (AI) at the output of the signal processor is used only to declare detections and provide measurements. We show that the AI can be used in passive sonar system, with or without frequency measurements, in the estimation process itself to enhance the performance in the presence of clutter where the target-originated measurements cannot be identified with certainty, i.e., for “low observable” or “dim” (low signal-to-noise ratio (SNR)) targets. A probabilistic data association (PDA) based maximum likelihood (ML) estimator for target motion analysis (TMA) that uses amplitude information is derived. A track formation algorithm and the Cramer-Rao lower bound (CRLB) in the presence of false measurements, which is met by the estimator even under low SNR conditions, are also given. The CRLB is met by the proposed estimator even at 6 dB in a cell (which corresponds to 0 dB for 1 Hz bandwidth in the case of a 0.25 Hz frequency cell) whereas the estimator without AI works only down to 9 dB. Results demonstrate improved accuracy and superior global convergence when compared with the estimator without AI. The same methodology can be used for bistatic radar