A Rigorous Architectural Approach to Adaptive Software Engineering

The engineering of distributed adaptive software is a complex task which requires a rigorous approach. Software architectural (structural) concepts and principles are highly beneficial in specifying, designing, analysing, constructing and evolving distributed software. A rigorous architectural approach dictates formalisms and techniques that are compositional, components that are context independent and systems that can be constructed and evolved incrementally. This paper overviews some of the underlying reasons for adopting an architectural approach, including a brief “rational history” of our research work, and indicates how an architectural model can potentially facilitate the provision of self-managed adaptive software system. Much of the research has been supported by the Engineering and Physical Sciences Research Council and is currently partly supported by EPSRC Platform grant AEDUS 2 and a DTC grant.     

Isochoric (p-π-T) measurements on liquid and gaseous air from 67 to 400 K at pressures to 35 MPa

Comprehensive isochoricp--T measurements have been carried out on liquid and gaseous air along 16 isochores at densities ranging from 2 to 32 mol · dm^–3. The air mixture has a nominal composition of 0.7813 N₂ + 0.2096 O₂ + 0.0092 Ar. Thep--T data cover a temperature range from 67 to 400 K at pressures up to 35 MPa. Comparisons with experimental results from independent sources are presented using a fundamental equation of state based. in part, on thep--T data from this study.     

Isochoric p-ρ-T Measurements on 1,1-Difluoroethane (R152a) from 158 to 400 K and 1,1,1-Trifluoroethane (R143a) from 166 to 400 K at Pressures to 35 MPa

The p--T relationships have been measured for 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) by an isochoric method with gravimetric determinations of the amount of substance. Temperatures ranged from 158 to 400 K for R152a and from 166 to 400 K for R143a, while pressures were up to 35 MPa. Measurements were conducted on compressed liquid samples. Determinations of saturated liquid densities were made by extrapolating each isochore to the vapor pressure, and determining the temperature and density at the intersection. Published p--T data are in good agreement with this study. For the p--T apparatus, the uncertainty of the temperature is ±0.03 K, and for pressure it is ±0.01% at p>3 MPa and ±0.05% at p<3 MPa. The principal source of uncertainty is the cell volume (28.5 cm³), which has a standard uncertainty of ±0.003 cm³. When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k=2 and thus a two-standard deviation estimate) of the density measurements is estimated to be ±0.05%.     

The Koala component model for consumer electronics software

Most consumer electronics today contain embedded software. In the early days, developing CE software presented relatively minor challenges, but in the past several years three significant problems have arisen: size and complexity of the software in individual products; the increasing diversity of products and their software; and the need for decreased development time. The question of handling diversity and complexity in embedded software at an increasing production speed becomes an urgent one. The authors present their belief that the answer lies not in hiring more software engineers. They are not readily available, and even if they were, experience shows that larger projects induce larger lead times and often result in greater complexity. Instead, they believe that the answer lies in the use and reuse of software components that work within an explicit software architecture. The Koala model, a component-oriented approach detailed in this article, is their way of handling the diversity of software in consumer electronics. Used for embedded software in TV sets, it allows late binding of reusable components with no additional overhead     

Matching three-dimensional objects using silhouettes

A method for matching three-dimensional objects against a library of models from an observed sequence of silhouettes is presented in this correspondence. Based upon the observed silhouettes, the three-dimensional structure of the object is constructed and refined. The principal moments and three primary silhouettes are computed for the constructed three-dimensional objects to represent the aggregate and detailed structure parameters. The adaptive matching technique requires that sufficient silhouettes be added to modify the structure of the unknown object until consistent and steady matching results are obtained. The library for matching is based on three primary silhouettes of the model objects. Experiments conducted show a fast convergence to a consistent result may be achieved provided that a reasonable choice of silhouettes is made.     

Studies on the dechlorination and detoxificaton of organochlorine compounds. I. PCBs and PCNs

In the analysis of organochlorines such as polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs), levels of, for example, PCB concentration are often expressed as a ‘total PCB’ value, using a straight GC pattern-matching technique with electron capture detection. Such methods provide little information about the identity of the individual components. In the present study, preliminary investigations using dechlorination with a NiCl₂/NaBH₄ catalyst indicated that the technique offered a comprehensive method for the analysis of PCBs and PCNs, as well as a method of detoxification of the ‘priority pollutants’ . This paper reports the use of capillary column GC-MS with an ion trap detector (ITD^TM) for the analysis of a number of PCBs and PCNs, including the commercially produced Aroclor 1254 and 1221, employing this dechlorination technique.