The challenge of introducing an exergy indicator in a local law on energy

Extending the exergy concept to practitioners and policy makers is still a major challenge. Recently the “Canton of Geneva” in Switzerland introduced a new law governing the procedures of attribution of building permits for new or retrofitted city areas. Authorities were asked to define a procedure including the calculation of an exergy indicator to be quantified in each file concerning large projects submitted for acceptance. This paper summarizes the problem definition, a clarification of the limits expected from the exergy indicator as well as the spreadsheet tool and the tables used to facilitate this quantification both for heating and air conditioning. For simplification the overall system was divided into a superstructure formed by four subsystems including the room convector, the plant of the building, a possible district heating and cooling plant and an external power plant. Three temperature ranges were considered for the building distribution networks both in heating and cooling. Ten different technology combinations were considered ranking from the lowest heating exergy efficiency with nuclear electricity and joule heating to the best efficiency with hydroelectricity and District heating electric heat pumps using lake water.     

New threats and attacks on the World Wide Web

Ten years ago, very few networks had a firewall; today, they're ubiquitous. The newest target is the workstation: client-side attacks have increased because direct attacks on servers aren't so easy any more. Moreover, as new defenses are raised, information flows are increasingly embedded into Web applications, making them extremely valuable as well, and, thus, the next target. This article describes some of these new threats.     

Influence of the polymerization temperature on the reactivity of 3-methyl- and 4-methyl-styrenes in cationic polymerization

The variations with respect to temperature of the reactivities of 3-methyl- and 4-methyl-styrenes in cationic polymerization have been studied by determination of their reactivity ratios with styrene.     

Trends and interactions of physical and bio-geo-chemical features in the Adriatic Sea as derived from satellite observations

Time series of satellite data, generated by the AVHRR (1981-1999), CZCS (1979-1985) and SeaWiFS (1998-2002), have been used to assess trends and interactions of physical and bio-geo-chemical features in the Adriatic Sea. The images were processed to estimate Sea Surface Temperature (SST) and Chlorophyll-like Pigment Concentration (CPC). Long-term composites and climatologies were derived, using fixed geographical grids and projections. The AVHRR data show an apparent warming trend, when plotting the sequence of seasonal cycles (monthly mean SST, averaged over the whole basin) against time, due to a steady rise of summer values. Considering 3 regions (north, central and south), split into east and west sections, the northern Adriatic shows high SST fluctuations (possibly associated with the cycle of winter cooling and summer warming, typical of the relatively shallow sub-basin), while the southern Adriatic exhibits a lower variability (possibly influenced by the periodic water incoming from, and outflowing to the Ionian Sea). During summer, an east-west gradient prevails, while during winter only a general north-south gradient can be found. The SeaWiFS-derived CPC values, distributions and trends appear to be consistent with the historical CZCS record. Persistent differences in the quantitative assessment of CPC for coastal waters is due to the use of improved algorithms, less influenced by the presence of dissolved organics and suspended sediments in the water column, for the processing of SeaWiFS data. Apparent incongruities of the space and time patterns in the SeaWiFS record with respect to the reference climatology, obtained by CZCS more than a decade before, occur chiefly when considering the spring bloom in the southern Adriatic and the summer development of the north Adriatic front. The comparison of the long-term times series of satellite data shows that there is a high correlation between patterns in the thermal field and in the colour field. This suggests that different surface waters, identified by the SST index, are also traced by different ecological features, identified by the CPC index. Both indices also show a high correlation with the classical cyclonic circulation scheme of the Adriatic Sea, proposing once again an intimate relationship between the water dynamics and its bio-geo-chemistry.     

Computation and stability analysis for regularized tomographicreconstructions

Deals mainly with the assessment of the stability of various reconstruction methods for computed tomography. The authors also present the convex dual formulation of the optimization problems in entropy-like methods. For each of these methods, the influence of errors in the measured data on the reconstructed image is analyzed. A small perturbation of the data vector induces a perturbation of the reconstructed image which can be computed by means of the sensitivity matrix. Using appropriate matrix computation techniques, an upper bound on the size of the reconstruction error is determined, as well as the pattern of noise in the sinogram that will result in the largest reconstruction error and the standard deviation map in the reconstructed image domain. Simulations illustrate the authors' analysis and demonstrate its utility in the interpretation of computed images and in the selection of reconstruction parameters     

LCA tool for the environmental evaluation of potable water production

Environmental impact assessment will soon become a compulsory phase in future potable water production projects, especially when alternative treatment processes such as desalination are considered. An impact assessment tool is therefore developed for the environmental evaluation of potable water production. The evaluation method used is the life cycle assessment (LCA) method. The quick and easy assessment of energetic and environmental performances contributes to determine the weak points of potable water production processes or the best suited treatment in a specific context. Studies of some potable water supply scenarios (groundwater treatment, ultrafiltration, nanofiltration, seawater reverse osmosis and thermal distillation associated to water transfer) are presented in order to illustrate the environmental information drawn from this tool. The main source of impacts is shown to be electricity production for plant operation. Improvement levers are presented for impact reduction and for the objective comparison between alternative and conventional water treatment processes.     

Tomographic formulation of interferometric SAR for terrainelevation mapping

Topographic mapping with spotlight synthetic aperture radar (SAR) using an interferometric technique is studied. Included is a review of the equations for determination of terrain elevation from the phase difference between a pair of SAR images formed from data collected at two differing imaging geometries. This paper builds upon the systems analysis of Li and Goldstein in which image pair decorrelation as a function of the “baseline” separation between the receiving antennas was first analyzed. In this paper correlation and topographic height error variance models are developed based on a SAR image model derived from a tomographic image formation perspective. The models are general in the sense that they are constructed to analyze the case of single antenna, two-pass interferometry with arbitrary antenna line of sight, and velocity vector directions. Correlation and height error variance sensitivity to SAR system parameters and terrain gradients are studied     

Reaction of α, ω-dicarboxy polyamides in the melt: synthesis of a model

Summary The synthesis of N-dodecanoyl-11-aminoundecanoic acid as a model for carboxylic polyamides 11 is described. The solubilization reaction of these polyamides with trifluoroacetic anhydride is studied by ¹H and ¹³C NMR spectroscopy. The resulting soluble trifluoroacetylated compounds are stable enough to allow an easy GPC study in CH₂Cl₂ on routine instument and columns. The participation of the residual dodecanoic acid in the polycondensation equilibrium of carboxylic polyamides has been established.