Rewiring strategies for changing environments

A typical pervasive application executes in a changing environment: people, computing resources, software services and network connections come and go continuously. A robust pervasive application needs adapt to this changing context as long as there is an appropriate rewiring strategy that guarantees correct behavior. We combine the MERODE modeling methodology with the ReWiRe framework for creating interactive pervasive applications that can cope with changing environments. The core of our approach is a consistent environment model, which is essential to create (re)configurable context-aware pervasive applications. We aggregate different ontologies that provide the required semantics to describe almost any target environment. We present a case study that shows a interactive pervasive application for media access that incorporates parental control on media content and can migrate between devices. The application builds upon models of the run-time environment represented as system states for dedicated rewiring strategies

Towards more sustainable construction–application of superabsorbent polymers in cementitious matrices with reduced carbon footprint

Construction industry is constantly searching for sustainable innovations to mitigate negative environmental impacts. Ground granulated blast-furnace slag (GGBS) is a well-known supplementary cementitious material which contributes to reduction of energy and CO2 emissions from cement industry. However, its use in cementitious systems leads to materials with high cracking susceptibility due to their greater autogenous shrinkage triggered by self-desiccation processes. This problem is even more pronounced when concrete is exposed to severe dry-hot weather conditions, such as in North Africa. In order to mitigate this negative effect of cracking, internal curing agents in the form of Superabsorbent polymers (SAP) can be successfully used. This approach leads to more durable cement based materials and in turn more sustainable constructions

Repeated autogenous healing in strain-hardening cementitious composites by using superabsorbent polymers

info:eu-repo/semantics/publishe

Existence dependency: conceptual modelling by contract.

In Object Orientation, the Generalisation/Specialisation hierarchy and the Whole/Part relationship are prevalent classification schemes for object types. This paper presents a new classification scheme for object types, called 'existence dependency'. Existence dependency captures some of the interesting semantics that are usually associated with the concept of aggregation (Part of relation). In fact, the semantics of existence dependency are hidden in the semantics of the Entity Relationship model, but have never been explicitly named. We will demonstrate how the explicit classification of object types according to the existence dependency relation allows for formal and automatic consistency between static and dynamic aspects of object types that goes far beyond mere syntactical consistency.Classification; Dependency; Model;

Effect of sample age on the self-healing properties of cementitious mateials with superabsorbent polymers

To obtain sustainable construction materials, occurring cracks in concrete should be repaired. However, as this often manual repair is time-consuming and expensive, self-healing may provide a solution. Autogenous healing is an already-present feature in cementitious materials, but it is an inferior mechanism as it can only heal cracks up to 30 μm in the presence of water. Therefore, a cementitious material with synthetic microfibres and superabsorbent polymers (SAPs) is proposed. Synthetic microfibres cause multiple crack formation with small healable cracks. Furthermore, SAPs are able to extract moisture from the environment and to provide it to the cementitious matrix for autogenous healing. But, if the building blocks are exhausted in time due to ongoing hydration, healing may be less efficient. In this study, the ability of (promoted) autogenous healing in time (7 days, 28 days, 3 months and 1 year) is investigated by comparing the mechanical properties after performing four-point-bending tests in different mixtures. The specimens were first loaded to 1% strain, stored in wet/dry cycles for 28 days and were subsequently reloaded. The results show that, with increasing age, the crack width decreases and a higher water-to-binder ratio tends to increase the mean and maximum crack width. All specimens are able to heal and to regain some of the mechanical properties after being preloaded and pre-cracked under four-point-bending. If SAPs are added, there is even healing in an environment without liquid water (relative humidity of more than 90%). At early age, the healing is governed by further hydration and calcium carbonate crystallization. At later ages (after one month), the main autogenous healing mechanism is the formation of calcium carbonate crystals. The amount of white precipitated healing products was higher in specimens with a higher water-to-cement ratio. Cracks in the specimens with fly ash were better closed in comparison with the samples with pure cement and blast-furnace-slag-blended mortars. Mixtures with SAPs showed more healing. The cementitious composite with microfibres and SAPs thus shows good self-healing in time

Generic object models and business process (re)design.

This paper explores the capacities of generic object-relationship models in the context of business process modeling and business process re-engineering. The presentation is based on a framework for strategic business function typology. It is shown how generic models can be developed for each kind of business function within the typology. Business process re-engineering can be represented by transformations of business models, corresponding to shifts within the typology framework. Although the results of the paper are presented by means of one particular dialect of the object-relationship approach, the results remain valid for all object oriented approaches that make use of objects and relationships. This paper contributes to the further formalisation of business process modeling.Models; Model; Processes;