W. Gareth J. Howells

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Questionnaire surveys, while more economical, typically achieve poorer response rates than interview surveys. We used data from a national volunteer cohort of young adult twins, who were scheduled for assessment by questionnaire in 1989 and by interview in 1996-2000, to identify predictors of questionnaire non-response. Out of a total of 8536 twins, 5058(More)
A number of different Model Transformation Frameworks (MTF) are being developed, each of them requiring a user to learn a different language and each possessing its own specific language peculiarities, even if they are based on the QVT standard. To write even a simple transformation, these MTFs require a large amount of learning time. We describe in this(More)
Although there are a large number of academic and industrial model transformation frameworks available, allowing specification, implementation, maintenance and documentation of model transformations which provide a rich set of functionalities, such tools are inherently complex. In particular, for a newcomer to the field of model transformation and for(More)
A significant current software engineering problem is the conceptual mismatch between the abstract concept of an association as found in modelling languages such as UML and the lower level expressive facilities available in object-oriented languages such as Java. This paper introduces some code generation patterns that aid the production of Java based(More)
In traditional cryptosystems, user authentication is based on the possession of secret keys/tokens. Such keys can be forgotten, lost, stolen, or may be illegally shared, but an ability to relate a cryptographic key to biometric data can enhance the trustworthiness of a system. In this paper, we demonstrate how biometric keys can be generated directly from(More)
The majority of the iris recognition algorithms available in the literature were developed to operate on near infrared images. A desirable feature of iris recognition systems with reduced constraints such as potential operability on commonly available hardware is to work with images acquired under visible wavelength. Unlike in near infrared images, in(More)
The problem of the incorporation of pattern features with unusual distributions is well known within pattern recognition systems even if not easily addressed. The problem is more acute when features are derived from characteristics of given integrated electronic circuits. The current paper introduces novel efficient techniques for normalising sets of(More)
With the continuing rise in the complexity of embedded systems, there is an emerging need for a higher level modeling environment that facilitates efficient handling of this complexity. The aim here is to produce such a high-level environment using ModelDriven Development (MDD) techniques that map a high-level abstract description of an electronic embedded(More)
There is an increasing need to develop flexible, reconfigurable, and intelligent multi-spacecraft sensing networks for aerospace-based monitoring and diagnostics. Technical advancements in ad hoc networking, MEMS devices, low-power electronics, adaptive and reconfigurable hardware, microspacecraft, and micro-sensors have enabled the design and development(More)