Abstract-For general (modular) system development with verification and validation (V&V), the V Model is the industrial standard. For component-based development, there is a wellunderstood standard process, but it does not specifically address V&V. In this paper, we propose such a model, that we call the W Model. We have implemented it using Model-Driven Engineering.

Many studies addressed radon (Rn 222 ) gas concentration levels in a number of locations in Jordan. But, none investigated the level of awareness of Jordanians of radon and its harmful effects on public health. In this study, a sample of 200 participants has been tested for their knowledge of radon and its effects on human health. The authors estimated that 63.1% are unaware of this gas and its respective effects on their health

Abstract. We believe that for developing applications in a specific domain, the best kind of software component model to use is a domain-specific one. We also believe that current component models intended for specific domains are actually not domain-specific. In this paper we present an approach for deriving domain-specific component models from the domain model of a given domain, and show why such a component model is better than existing models that are not domain-specific.

Abstract. Data encapsulation is a familiar property in object-oriented programming. It is not only useful for modelling things in the real world, but it also facilitates reuse by enabling the creation of multiple instances of the same class, each with its own identity and private data. For CBSE, this kind of reuse is clearly also one of the key desiderata. However, it must be achieved in conjunction with composition, which is central to CBSE. In this paper we show how data encapsulation can be combined with composition, by extending a component model we have defined previously.

The widespread and desirable features of IP and IEEE 802.11 networks have made these technologies a suitable medium for carrying voice over IP (VoIP). However, a bandwidth (BW) exploitation obstacle emerges when 802.11 networks are used to carry VoIP traffic. This BW exploitation obstacle is caused by the large 80-byte preamble size of the VoIP packet and a waiting time of 765 μs for each layer 2 VoIP frame. As a solution, IEEE 802.11n was consequently designed with a built-in layer 2 frame aggregation feature, but the adverse impact on the VoIP performance still needed to be addressed. Subsequent VoIP research has proposed numerous enhancements to the built-in IEEE 802.11n aggregation techniques. In this study, we analyse and propose enhancements to the BW exploitation and VoIP performance over IEEE 802.11n. We also recommend new techniques to enhance VoIP performance via IEEE 802.11n frame aggregation implementations. Furthermore, we contribute guidelines for creating a robust, suitable, and reliable aggregation technique for VoIP over the 802.11n standard.