Discovering Services Is Not Enough

Faced with multiple electronic devices, service providers, and ISPs, tomorrow's mobile users might find it challenging to identify available services and acquire the rights to use them. The authors tackle this problem, combining the acquisition of role-based credentials with servicediscovery.     

OMI very fast delivery and the Sodankyla/spl uml/ Satellite Data Centre

The Ozone Monitoring Instrument (OMI) operates onboard the National Aeronautics and Space Administration's Earth Observing System Aura satellite, which was launched in July 2004. Like its sister spacecraft Terra and Aqua, Aura's capabilities include direct broadcast (DB), i.e., the ability to broadcast data at the same time as they are being measured and stored in the spacecraft's memory for later transmission to Earth. The Finnish Meteorological Institute's Satellite Data Centre at Sodankyla/spl uml/ in Finnish Lapland is exploiting this capability to receive OMI data while Aura is in sight of the receiver, which enables nearly immediate production of OMI data products for a region that includes a large part of Europe, stretching from the North Pole to the Italian Alps. The current OMI Very Fast Delivery (VFD) products include maps of surface UV-B, ozone columns, and cloud coverage.     

Enhanced antenna-pattern measurements for Satellite systems

This paper describes an enhanced measurement technique for earth-station antennas in a satellite communication system. A new data-acquisition algorithm improves the dynamic range of the measurements by increasing the signal-to-noise ratio in the test setup. The resolution limitation of conventional techniques is eliminated without any modifications to the ground station setup. The proposed approach improves the conventional measurement techniques by utilizing pulse modulation of the test-signal amplitude and its synchronous detection. The noise floor in the pattern is reduced by biasing out the average noise power calculated during the OFF cycle of the pulse. In addition, a randomly fluctuating local mean in the receiver output is reduced. Experimental results show improvements of as much as 25 dB in the noise variance and over 11 dB in the dynamic range of the antenna pattern.     

Conditions for the formation and the structure of a metastable cerium modification

Mathematical simulation of heat transfer processes and X-ray diffraction analysis were used to show that, upon the quenching of cerium from the melt at rates of greater than 3.5 × 10⁵ K/s, a metastable μ′-Ce modification with a seven-layer hexagonal structure is formed. The formation of μ′-Ce is explained by the accumulation and ordering of stacking faults in the fcc lattice of the γ phase leading the process of crystallization upon rapid cooling from the melt.     

Heat losses in a tunnel kiln for brick firing

The results of experimental studies of heat losses via the enclosing structures of an operating brick-firing kiln using a thermal imager are described. __________ Translated from Steklo i Keramika, No. 4, pp. 24–25, April, 2006.     

Cover Picture: Light‐Emitting Organic Solar Cells Based on a 3D Conjugated System with Internal Charge Transfer (Adv. Mater. 22/2006)

The cover image illustrates the dual photovoltaic and electroluminescence function of a single‐layer device based on a thienylenevinylene–triphenylamine with internal charge transfer (ICT), as reported by Cravino, Roncali, and co‐workers on p. 3033. The material forms an organic glass with isotropic electronic properties while ICT leads simultaneously to an extension of the photoresponse to the red and to an increase of the open circuit voltage. The use of an additional layer of C₆₀ further improves the photovoltaic. Images of the sun and moon courtesy NASA/JPL–Caltech.     

History of the stiffness method

This paper presents a brief history of the development of the stiffness method. We start by tracing the evolution of the method to solve discrete‐type problems such as trusses and frames composed of two node members. We then describe the method as it is applied to solve continuum problems modelled by finite‐difference and finite‐element methods. Copyright © 2006 John Wiley & Sons, Ltd.     

Mössbauer study of the Ge two-electron donor centers in PbSe

Mössbauer emission spectroscopy at ⁷³As(⁷³Ge) is used to show that the charge state of the ⁷³Ge antisite defect formed in the anion sublattice after the radioactive transformation of ⁷³As is independent of the position of the Fermi level. In contrast, the ⁷³Ge center in the cation sublattice of PbSe is an electrically active substitutional impurity. For the n-type samples, the spectrum corresponds to the neutral state of the donor center (⁷³Ge²⁺), and for the p-type samples, the spectrum corresponds to the doubly ionized state (⁷³Ge⁴⁺) of this center.