Safeguarded Processing of Sensor Data

International audienceThe spectrum of software tasks no longer includes only rare function controlling tasks for sensor actuator chains in reactive embedded systems. However, more and more responsible challenges like safety-critical scenarios are tackled. Therefore sensor data have to be safeguarded by several mechanism. An obvious and widely used approach is the use of two redundant hardware controllers, but this comes along with an additional cost, space and energy factor. Another way to fulfill certain safety properties is to implement a second diverse software channel in a single micro-controller architecture according the Safely Embedded Software (SES) approach. However, a lack of performance occurs by implementing this diverse channel for complex computations e.g. floating-point operations. This paper gives an approach for transferring the SES into a coprocessor and to migrate SES to a flexible and powerful FPGA architecture

Dubravka Peić Čaldarović, Nikša Stančić, Povijest hrvatskoga grba: Hrvatski grb u mijenama hrvatske povijesti od 14. do početka 21. stoljeća, Zagreb: Školska knjiga, 2011., 316 str.

A series of para-oligophenylene mono- and dicarboxylic acids (R-(C6H4)nCOOH, n=1-3, R=H,COOH) was studied. Adsorbed on Au(111)/mica modified by an underpotential deposited bilayer of Ag, the self-assembled monolayers (SAMs) were analysed by near edge X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy and scanning tunneling microscopy. In all cases SAMs are formed with molecules adopting an upright orientation and anchored to the substrate by a carboxylate. Except benzoic acid, all SAMs could be imaged at molecular resolution, which revealed highly crystalline layers with a dense molecular packing. The structures of the SAMs are described by a rectangular (5×√3) unit cell for the prevailing phase of the monocarboxylic acids and an oblique (√93×√133) unit cell for the dicarboxylic acids, thus, evidencing a pronounced influence of the second COOH moiety on the SAM structure. Density functional theory calculations suggest that hydrogen bonding between the SAM terminating COOH moieties accounts for the difference. Contrasting other classes of SAMs, the systems studied here are determined by intermolecular interactions whereas molecule-substrate interactions play a secondary role. Thus, eliminating problems arising from the mismatch between the molecular and substrate lattices, coordinatively bonded carboxylic acids on silver should provide considerable flexibility in the design of SAM structures

Wavelength dependent isotope fractionation in visible light O3 photolysis and atmospheric implications

The O-17 and O-18 isotope fractionation associated with photolysis of O-3 in the Chappuis band was determined using a broadband light source with cutoff filters at 455, 550, and 620 nm and narrowband light sources at 530, 617, and 660 nm. The isotope effects follow a mass- dependent fractionation pattern ( delta O-17/delta O-18 = 0.53). Contrary to theoretical predictions, fractionations are negative for all wavelength ranges investigated and do not change signs at the absorption cross-section maximum. Our measurements differ from theoretical calculations by as much as 34% in (18)epsilon(O3+hv) = ((18)J/(16)J - 1). The wavelength dependence is also weaker than predicted. Photo-induced fractionation is strongest when using a low-wavelength cutoff at 620 nm with (18)epsilon(O3+hv) = -26.9(+/- 1.4)parts per thousand. With decreasing wavelength, fractionation values diminish to (18)epsilon(O3+hv) = -12.9(+/- 1.3)parts per thousand at 530 nm. Results from an atmospheric model demonstrate that visible light photolysis is the most important tropospheric sink of O-3, which thus contributes about one sixth to the ozone enrichment