Dual-Priority versus Background Scheduling: A Path-Wise Comparison

In this paper, two well-known scheduling policies for real-time systems, namely background scheduling (BS) and dual-priority (DP) are compared in terms of response times for soft real-time traffic (SRT). It is proved in the preemptive as well as in the non-preemptive case that, when the SRT traffic is FIFO, the DP policy always outperforms BS for all instances of SRT tasks. When the SRT traffic is not FIFO but if all tasks are of equal size then, in the non-preemptive case, the average response times is shown to be always better under DP than under BS. As a complementary result, some non-FIFO examples where BS behaves better than DP for some SRT tasks but also on the average of the SRT response times, are given. The proofs are based on a trajectorial method that may be used for comparing other scheduling policies.     

Visual routines for real-time monitoring of vehicle behavior

Low-cost, purely visual modules are presented, which are able to reliably perform real-time computation of kinematic quantities relevant for the navigation of commercial vehicles moving along highways or motorways. Taking as input a video stream of b/w images coming from a standard camera mounted aboard the vehicle, the modules return instantaneous measurements for the speed of the vehicle, its lateral position in the lane, and the distance from the preceding vehicle. The modules, which are designed to work in real-time on standard PC platforms, have been tested under typical working conditions. Preliminary results are reported and discussed. Received: 10 March 1997 / Accepted: 24 November 1997     

Physical Metallurgy of Multi‐Phase Steel for Improved Passenger Car Crash‐Worthiness

The dynamic testing of high strength automotive steel grades is of great practical importance if their crash‐worthiness is to be evaluated. During forming operations, steels are processed in a controlled dynamic manner. In collisions, the deformation is different in the sense that the deformation is not controlled, i.e. both strain and strain rate are not pre‐determined. No clear standard testing procedures are currently available to test high strength steels dynamically, in order to evaluate their performance during car crashes. High tensile strength TRIP‐aided steels have been developed by the steel industry because of their promising high strain rate performance. The present contribution focuses on the effect of the strain rate and temperature on the mechanical behaviour of the low alloy high strength TRIP steel. The tests were carried out on the separated phases in order to determine their specific high strain rate deformation response. The temperature‐dependence of the transformation rate of the retained austenite is presented. It is argued that the adiabatic conditions present during high strain rate deformations have a beneficial effect on the behaviour of TRIP steel.     

Role of nanometer roughness on the adhesion and friction of a rough polymer surface and a molecularly smooth mica surface

Friction and adhesion measurements between surfaces of cross-linked, stiff polymers of varying roughness against smooth, bare mica surfaces were carried out in dry air as well as in the presence of lubricating oil. The nominal (macroscopic) contact area varies with the applied load according to the Johnson, Kendall and Roberts (JKR) theory, yet shows significant hysteresis due to the irreversibility arising from the loading/unloading curves of multiple asperities. Upon introducing the oil between the surfaces, the critical shear stress is reduced to zero due to the elimination of the adhesion force. However, the effect is less noticeable on the friction coefficient. Lastly, the effect of increasing the (RMS) roughness was greatest over the first few nanometers due to the diminution of the adhesion-controlled contribution to the friction, after which a further increase in roughness had less dramatic effects. A model is presented to account for the observed adhesion hysteresis during repeated loading/unloading cycles of purely elastically deforming rough surfaces. Bruno Zappone and Kenneth J. Rosenberg made equal contributions.     

Carbazole based hole transporting materials for solid state dye sensitizer solar cells: role of the methoxy groups

The synthesis of new organic hole transporting materials (HTMs) based on 3,6‐disubstituted 9H‐carbazole‐3,6‐diamine,N,N,N′,N′‐tetraphenyl‐9‐(4‐methoxyphenyl) derivatives and their applications in solid state dye sensitizer solar cells (DSSCs) are described. The effect of the methoxy group localized on the para position of the diphenylamine moieties on the thermal, electronic and electrochemical properties and photovoltaic performance is discussed. In solid state DSSCs, utilization of the aforementioned HTMs in combination with the dye D102 (TiO₂/D102/HTM/Au) shows a positive influence of the methoxy group on the photovoltaic conversion efficiency compared with unsubstituted diphenylamine grafted groups. A study on the concentration of the HTM is also carried out and shows an optimal concentration around 200 mg mL^?1. Without further optimization, the best device gives a power conversion efficiency of 1.75% under AM 1.5 solar irradiation (100 mW cm^?2).     

Digital canvas removal in paintings

The periodic structure of the underlying support of paintings on canvas can become quite prominent and disturbing in high resolution digital recordings. In this paper, we construct a new model and method for the digital removal of canvas which is considered as a noise component superimposed on the painting artwork. The high resolution of the images prohibits the efficient application of existing adaptive denoising filters. Hence, a two-step approach is proposed. First a (smoothing) Wiener filter is applied to the complete image. The second step consists of a spatially adaptive extension with low-complexity to obtain a generic digital canvas removal filter.     

Prediction of Acid Mine Drainage: Importance of Mineralogy and the Test Protocols for Static and Kinetic Tests

Static tests, which compare the acid-generating potential and acid-neutralizing potential for a given mine waste (tailings or waste rocks), are characterized by a wide uncertainty zone in which it is impossible to accurately predict the acid-generating potential (AGP). Then, to better assess long-term AGP, kinetic tests are usually performed to provide more information about the reaction rates of the acid-generating and acid-neutralizing minerals. The present work compares the classic Sobek static test with three mineralogical static tests to assess the importance of sample mineralogy in acid mine drainage (AMD) prediction. We also investigated how experimental procedures related to static tests can influence prediction results. We used three synthetic tailings samples made by mixing well-characterized pure minerals in calibrated proportions. Although basically different in their principles and procedures, the modified Sobek and mineralogical static tests gave similar results. These AGP predictions were then validated by the use of a kinetic test. The kinetic test protocol was also modified in this study and the results obtained correlated well with the static test results, in contrast to the standard kinetic test protocol. The present work highlights the limitations of static and kinetic test procedures, and provides recommendations for a better use of these tests for more reliable AMD prediction.     

Variation in carotenoid–protein interaction in bird feathers produces novel plumage coloration

Light absorption by carotenoids is known to vary substantially with the shape or conformation of the pigment molecule induced by the molecular environment, but the role of interactions between carotenoid pigments and the proteins to which they are bound, and the resulting impact on organismal coloration, remain unclear. Here, we present a spectroscopic investigation of feathers from the brilliant red scarlet ibis (Eudocimus ruber, Threskiornithidae), the orange-red summer tanager (Piranga rubra, Cardinalidae) and the violet-purple feathers of the white-browed purpletuft (Iodopleura isabellae, Tityridae). Despite their striking differences in colour, all three of these feathers contain canthaxanthin (β,β-carotene-4,4′-dione) as their primary pigment. Reflectance and resonance Raman (rR) spectroscopy were used to investigate the induced molecular structural changes and carotenoid–protein interactions responsible for the different coloration in these plumage samples. The results demonstrate a significant variation between species in the peak frequency of the strong ethylenic vibration (ν₁) peak in the rR spectra, the most significant of which is found in I. isabellae feathers and is correlated with a red-shift in canthaxanthin absorption that results in violet reflectance. Neither polarizability of the protein environment nor planarization of the molecule upon binding can entirely account for the full extent of the colour shift. Therefore, we suggest that head-to-tail molecular alignment (i.e. J-aggregation) of the protein-bound carotenoid molecules is an additional factor.