Web-GIS models: accomplishing modularity with aspects

Spatial concerns of Web geographical information systems (Web-GIS) are inherently crosscutting and volatile: crosscutting because they affect multiple functionalities of Web-GIS systems, and volatile because their status may change often. If these concerns are not modularized properly, the quality of Web-GIS services, particularly with regard to adaptation and evolution, can be severely compromised. This paper uses aspect-orientation to model crosscutting and volatile spatial concerns. By modeling both types of concerns, crosscutting and volatile, as candidate aspects, one can use dynamic weaving to add or remove them from a system at runtime. The aspect-oriented approach proposed starts with the identification and specification of crosscutting concerns and follows by composing these using modeling aspects using a transformation approach, an aspect-oriented modeling technique. The conflicts that can emerge due to the composition order are also taken into consideration. Finally, this paper proposes a set of reusable GIS crosscutting concerns, documenting them in a concern catalogue.     

Heat-shrinkable films based on polyolefin waste

Polyethylene wastes (low-density polyethylene, high-density polyethylene and their binary blends) were subjected to high-energy radiation, using a ⁶⁰Co gamma radiation source. The crosslinked materials thus obtained were processed to heatshrinkable films. Tensile strength could be sharply improved by increasing the dose up to 20 Mrad, simultaneously increasing the elongation at break of the most degraded PE waste. An increase of the degree of compatibility of LDPE and HDPE waste was also observed. All samples examined exhibit a “memory effect” after drawing at 130°C and cooling under tension followed by further heating under relaxed conditions. The value of shrinkage depended on the degree of degradation of the PE waste and on the irradiation dose.     

Multinuclear magnetic resonance studies on the chemical interaction of a self-etching adhesive with radicular and coronal human dentin

This study presents evidence at molecular level for the chemical interaction between human dentin from different tooth regions and a monomer with phosphate groups, incorporated in the formulation of a simplified adhesive system. Because dentin was observed as a powder, previous verification was obtained for an eventual collagen denaturation due to the grinding process. The presence of chemical bonds involving coronal (CD) or radicular dentin (RD) was investigated using multinuclear magnetic resonance (MR) techniques. Narrow signals were identified in the carbon magic angle spinning (MAS) spectra of CD and RD treated with the adhesive, which were assigned to methylenic groups in methacryloyloxydecyl dihydrogen phosphate (MDP) bound to hydroxyapatite Ca²⁺; ¹H spectra of the adhesive components and treated dentin, in ethanol, support this conclusion. ³¹P MAS spectra obtained from both dentin regions present additional shielding and broadening effects subsequent to application and photopolymerization of the adhesive, which were higher for CD. Multinuclear MR studies provided evidence for the interaction of the adhesive with dentin, which involves hydroxyapatite and is stronger for CD than for RD, but no direct proof was obtained on bonding to collagen.     

Study of plastic compounds containing polypropylene and wood derived fillers from waste of different origin

The scope of the article was to study the perspectives of the using of wood derived fillers (WDF) from waste of different origin as fillers of polypropylene. The WDF used in this study was hard wood flour (HW), birch veneer polishing dust (VD) and tetra‐pack carton cellulose fiber (TC). Some mechanical strength parameters, water uptake in the static and cyclic test and resistance to fungal decay of polypropylene (PP) composites containing these three types of WDF were studied and compared with similar loading (40 wt %) talc‐filled PP. Composites containing TC and VD fibers as filler showed the highest flexural strength at three test temperatures (?40, +20, and +40°C) and flexural modulus and tensile strength at plus temperatures. On the other hand talc‐filled PP exhibited greatest flexural modulus at minus temperature, greatest impact strength at room temperature and best flow ability. Significant difference was observed between PP composites with HW and VD fillers regarding water uptake in cyclic tests, however flexural strength and modulus change of composites were reversible after drying. No weight loss of WDF/PP composites was observed after 6 week exposure to brown‐ and white‐rot fungi, however, degradation of the surface of samples was detected by SEM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study of blends based on recycled polyethylene wastes

Data covering the physical properties of molten and solid samples of two binary blends of recycled polyethylene wastes, in a wide range of compositions, are reported. While some properties (density, fusion enthalpy) show a linear behaviour with composition other properties (microhardness, yield stress) show a deviation from linearity. Deviation of microhardness additivity of the single components has been interpreted, after analysis of the DSC thermograms, as being due to segregation and recombination of molecular species from both components during crystallization. It is also suggested that the presence of a high oxidation in one low-density polyethylene component, detected by infrared spectroscopy, influences the very low values observed for the melt flow index and melt elongation at break.     

Dam-Break Flood Emergency Management System

Natural or induced floods are of increasing concern to watermanagers and civil protection services for three main reasons.Firstly, a continuous and 'unconscious' increase of socialpressure in the flooding valleys amplifies flood vulnerabilitiesand consequently natural or induced flood risk. Secondly, thealarming forecasts of the impact of potential climate changes onwater resources, in spite of the high uncertainty associated tothese forecasts, points out to larger flood hazards. Thirdly,dam-break induced accidents may occur more frequently due toinfrastructure aging.Emergency Planning is a non-structural measure to minimise floodimpacts playing an important role in crisis management. In fact,if a disaster cannot be avoided, individual and social structurepreparedness may be of great help in risk reduction.An Internet-based system that supports flood emergencymanagement is presented in this article. This application is partof a more complete system, developed with the goal of endowingthe Portuguese water authorities, dam owners and the civilprotection system, with adequate tools to store and easilyretrieve information on dams and their downstream valleys, tomodel the flood wave induced by a dam break and, eventually, tomanage the response to flood-induced catastrophes.     

Study of blends based on recycled polyethylene wastes

A calorimetric study of binary blends based on recycled, low and high density polyethylene, wastes is presented. The physical properties of these blends were reported previously [1]. A comparison between the first and second differential scanning calorimetry (DSC) traces of blended samples reveals the presence of an intermediate endothermic peak which can be associated to the melting of crystals from mixed molecular species of the single components. Further thermal treatments after the second DSC run at temperatures just below and above the intermediate peak for two compositions (_B = 10 and 30% of high density component) highlight the dependence of the various crystal populations upon annealing. A quantitative analysis of a series of consecutive thermograms for each sample has allowed us an estimation of the relative amount of material associated to the three main endothermic peaks.     

The effect of paraffin on fiber dispersion and mechanical properties of polyolefin–sawdust composites

This article reports on the influence of the paraffin (PAR) on the wood fiber (WF) dispersion in different polyethylene (low‐density polyethylene, high‐density polyethylene, recycled polyethylene) matrices, as well as on the melt flow behavior and mechanical properties of WF‐reinforced polyethylene (PE) composites. In the presence of paraffin, the composites showed improved tensile and flexural strength and modulus, but lower impact strength and elongation at break. The extent of improvement in mechanical properties depends on paraffin content and type of polyethylene; the most effective paraffin was in LDPE‐based composites. Paraffin‐treated WF showed lower moisture absorption ability in comparison with unmodified wood fiber. The phase segregation process was investigated for PE/PAR blends by DSC method. It was shown that an increase of paraffin concentration in the PE/PAR blend leads to a decrease of PE melting temperature and an increase of paraffin melting temperature; it indicates a net exchange of material from paraffin towards polyethylene. However, generally both components of PE/PAR blends remain immiscible. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2385–2393, 2004     

Evidence for higher biomagnification factors of lower chlorinated PCBs in cultivated seabass

Thirty three PCB congeners were analyzed in three size classes of seabass (Dicentrarchus labrax), from a semi-intensive fish farm, in food and in abiotic compartment. Water and suspended particulated matter (SPM) showed higher concentrations of lower chlorinated PCBs, whereas fish tissues and food showed higher concentrations of CB153 and CB138. In order to examine the influence of different inputs to seabass contamination, bioaccumulation factors (BAF), biota-suspended particulate matter bioaccumulation factors (BSMAF) and biomagnification factors (BMF) were calculated. In general, the log BAF and log BSMAF showed good correlations with log K(ow), for congeners with log K(ow)>6.1. In three fish size classes, PCB congeners with log K(ow)<6.1 were found at concentrations higher than what was expected based on the BAF calculated for the more hydrophobic congeners, suggesting a different contribution of sources. The application of a mass balance model for accumulation of some congeners in seabass estimated concentrations in fish 3- to 38-fold higher than the measured values, probably by overestimating gill absorption. The model was applied with other scenarios in order to maximize uptake from food, which may have a significant influence in accumulation, and not only from diet pellets. Its contribution to fish contamination for highly chlorinated PCBs may reach a maximum of 54-64%, and for lower chlorinated PCBs its contribution is lower than 20%. In this work it was proved that to reduce fish contamination the quality of the water should be controlled.