Application of Gram-Schmidt algorithm to fully adaptive arrays

The Gram-Schmidt orthogonalization (GSO) algorithm has excellent numerical performance and is readily applicable to systolic implementations such as in a field of adaptive cancellation systems. A modified GSO algorithm for a fully adaptive array is proposed and computer simulations show that the proposed algorithm gives superior performance. A systolic implementation of the proposed GSO algorithm for fully adaptive array is presented. A feedback mode GSO algorithm for use with analog weights is also presented and has been shown to have excellent performance in the presence of weight errors     

SWE,a comprehensive plasma instrument for the WIND spacecraft

The Solar Wind Experiment (SWE) on the WIND spacecraft is a comprehensive, integrated set of sensors which is designed to investigate outstanding problems in solar wind physics. It consists of two Faraday cup (FC) sensors; a vector electron and ion spectrometer (VEIS); a strahl sensor, which is especially configured to study the electron strahl close to the magnetic field direction; and an on-board calibration system. The energy/charge range of the Faraday cups is 150 V to 8 kV, and that of the VEIS is 7 V to 24.8 kV. The time resolution depends on the operational mode used, but can be of the order of a few seconds for 3-D measurements. Key parameters which broadly characterize the solar wind positive ion velocity distribution function will be made available rapidly from the GGS Central Data Handling Facility.     

Radiative and hybrid cooling of infrared space telescopes

The designs of cold space telescopes, cryogenic and radiatively cooled, are similar in most elements and both benefit from orbits distant from the Earth. In particular such orbits allow the anti-sunward side of radiatively-cooled spacecraft to be used to provide large cooling radiators for the individual radiation shields. Designs incorporating these features have predictedT _tel near 20 K. The attainability of such temperatures is supported by limited practical experience (IRAS, COBE). Supplementary cooling systems (cryogens, mechanical coolers) can be advantageously combined with radiative cooling in hybrid designs to provide robustness against deterioration and yet lower temperatures for detectors, instruments, and even the whole telescope. The possibility of such major additional gains is illustrated by the Very Cold Telescope option under study forEdison, which should offerT _tel5 K for a little extra mechanical cooling capacity.     

Computer simulation of IGBT losses in PFC circuits

An analysis is presented that forms the basis for an algorithm for calculating the IGBT losses in a power factor correction (PFC) circuit. The method employs experimental data from an off-line test circuit that closely resembles the switching conditions in the actual PFC. This technique provides calculated values of both the conduction and switching losses of the main transistor in a boost-type PFC circuit. Results for a 6 kW PFC are included     

Neural controllers for systems with unknown dynamics

This study presents a methodology for specifying a neural controller for a system about which no a priori model information is available. The neural design presumes that a finite duration input/output (I/O) histogram on the system is available. The design procedure extracts from the histogram sufficient information to specify the neural feedback controller. The resultant controller will drive the system along a general output reference profile (unknown during the design). The resultant controller also exhibits the capability of disturbance rejection and the capacity to stabilize unstable plants     

Wind asymmetries in massive stars

We are in the process of surveying the linear polarization in luminous, early-type stars. We here report on new observations of the B [e] stars S 18 and R 50, and of the Luminous Blue Variables HR Car, R 143, and HD 160529. Together with previously published data, these observations provide clear evidence for the presence of intrinsic polarization in 1 B[e] star (HD 34664) and in 5 LBVs ( Car, P Cyg, R 127, AG Car, and HR Car). The data indicate that anisotropic stellar winds are a common occurrence among massive stars in these particular evolutionary stages. For such stars, mass-loss rates estimated using the assumption of a spherical, homogeneous and stationary outflow may be in error.     

The Solar and Cosmic-Ray Synodic Periodicity (1969–1998)

The synodic recurrence of the Mt. Wilson plage index (MPSI) and the Calgary cosmic ray (CR) intensity is investigated, using the wavelet power spectra in the range of 18–38 days, during the last three solar cycles. The unique temporal coincidence between the quasi–synodic MPSI and the CR periods is detected in 1978–1982 (the 21st solar cycle). In the 22nd cycle there is a very strong MPSI synodic recurrence, from 1989.5 to 1990.5, but it is absent in the CR data. In 1992.5–1993.5 the MPSI and CR recurrence phenomenon is in good accordance with the solar wind speed and cosmic ray modulation as measured during the first Ulysses passage around the Sun. The Gnevyshev gap is present in the 27-day recurrence of CR, in agreement with Kudela et al. (1999). This revised version was published online in August 2006 with corrections to the Cover Date.     

The Electron Radiation Belt

Electron radiation belts can change dramatically in a few seconds or slowly over years. Important issues in understanding such changes are: (1) What is the source of electrons in the radiation belts? (2) How important is radial diffusion compared to other radial transport mechanisms? (3) What are the detailed changes in the magnetosphere that produce radial diffusion? (4) Why is the response of the electron radiation belt to changes in the solar wind different from that of substorms and of the ring current? (5) Are processes other than radial transport, such as wave-particle interactions, important in energizing electrons in the radiation belts?     

Structure of a two-phase flow of boiling water at low-head adiabatic efflux through the laval nozzle

The critical flow conditions and structural forms of a two-phase flow that is formed during water efflux from the region of moderate and low pressures into a rarefied medium are analyzed. The difference in the structural forms of a flow realized at the low-head efflux from the structure of a flow occurring in the fluid flow with moderate and high initial pressures is established. The critical pressure differential characterizing the establishment of the maximum flowrate is determined and the decisive influence of turbulence on the vapor phase generation and flow conditions of a two-phase medium is shown.     

Wave resistance of rough plane channel walls in the supersonic flow

We propose a method that makes it possible to obtain in the framework of linear approximation the exact formulas for the wave resistance of the channel walls with an arbitrary plane pattern in the first and subsequent interference zones. It is shown by a particular example of the sinusoidal pattern that the pressure wave interference may lead to the positive or negative resistance resonance.