An ontology supported risk assessment approach for the intelligent configuration of supply networks

As progress towards globalisation continues, organisations seek ever better ways with which to configure and reconfigure their global production networks so as to better understand and be able to deal with risk. Such networks are complex arrangements of different organisations from potentially diverse and divergent domains and geographical locations. Moreover, greater focus is being put upon global production network systems and how these can be better coordinated, controlled and assessed for risk, so that they are flexible and competitive advantage can be gained from them within the market place. This paper puts forward a reference ontology to support risk assessment for product-service systems applied to the domain of global production networks. The aim behind this is to help accelerate the development of information systems by way of developing a common foundation to improve interoperability and the seamless exchange of information between systems and organisations. A formal common logic based approach has been used to develop the reference ontology, utilising end user information and knowledge from three separate industrial domains. Results are presented which illustrate the ability of the approach, together with areas for further work

Analysis of Vegetation Behavior in a North African Semi-Arid Region, Using SPOT-VEGETATION NDVI Data

The analysis of vegetation dynamics is essential in semi-arid regions, in particular because of the frequent occurrence of long periods of drought. In this paper, multi-temporal series of the Normalized Difference of Vegetation Index (NDVI), derived from SPOT-VEGETATION satellite data between September 1998 and June 2010, were used to analyze the vegetation dynamics over the semi-arid central region of Tunisia. A study of the persistence of three types of vegetation (pastures, annual agriculture and olive trees) is proposed using fractal analysis, in order to gain insight into the stability/instability of vegetation dynamics. In order to estimate the state of vegetation cover stress, we propose evaluating the properties of an index referred to as the Vegetation Anomaly Index (VAI). A positive VAI indicates high vegetation dynamics, whereas a negative VAI indicates the presence of vegetation stress. The VAI is tested for the above three types of vegetation, during the study period from 1998 to 2010, and is compared with other drought indices. The VAI is found to be strongly correlated with precipitation.Water Availability and Security in Southern EuRope and the Mediterranea

Monitoring epiready semiconductor wafers

GaAs wafers are often sold by the manufacturers as 'epiready', meaning the substrates can be used with no further treatment. However, there is no clear agreement what epiready means, although one manufacturer recommends that they be used within 3 months of purchase. However, many growers find they are unable to obtain good growth results from their processes with untreated wafers and have to resort to long-established etching procedures. With the increase in multi-wafer molecular beam epitaxy (MBE) and metal organic vapour phase epitaxy (MOVPE) reactors, this approach is no longer viable. This work investigates the ageing of GaAs wafers stored, both under a variety of conditions [e.g. temperatures of 200 degreesC, room temperature and -20 degreesC] and assessed by atomic force microscopy (AFM) after various procedures had been performed, including annealing in molecular hydrogen using a MOVPE reactor. The primary source of ageing on an epiready GaAs wafer has been found to be the transfer oxidation from the native As2O3 (present at time = 0) to Ga2O3 (present after 24 h, 3 months and 2 years, respectively, at the storage temperatures mentioned above). This transfer oxidation does not occur across the whole surface but in discrete areas that may be associated with the step edges on the substrate surface. This is the cause of deterioration of an epiready substrate, but it can be slowed by storing the GaAs wafers at -20 degreesC. Storage in a domestic freezer has allowed even 2-year-old GaAs wafers to be used without any further preparation. (C) 2002 Elsevier Science B.V. All rights reserved