Design of C-sections Against Deformational Lip Buckling

Deformational lip buckling is one of the considerations affecting the choice of cross-section dimensions which were adopted for the C-sectlon chord members of a space frame system. No guidance on lip buckling of channel sections is given in the current British design specification. A method was therefore required for determining the lip buckling resistance of the members when subjected to axial compression or bending. A design procedure was formulated in which the lips are represented as a strut on an elastic foundation, the stiffness of which depends on the deformational stiffness of the section. The critical buckling stress and the wavelength of buckling can then be determined. By assigning imperfections to the nominally straight lips, the critical lip buckling stress can be introduced into the Perry-Roberston formulation for the strength of columns, and the lip buckling strength can be estimated. Comparative resulis from the design formulation, experiments, and non-linear elasto-plasttc finite element analysis are given. It is shown that the proposed design model is satisfactory but conservative

Energetic, environmental and economic modelling of a solar-assisted residential micro-trigeneration system in a Mediterranean climate

Reducing energy consumption in buildings has become a priority for most countries. However, designing energy-efficient buildings is not a straightforward task - the increasing demand for high comfort standards, provided by conventional 'energy-hungry' cooling and heating devices conflicts with the need for demand reduction. Trigeneration, the simultaneous production of electricity, cooling and heating is often viewed as a means of improving energy-efficiency in large and medium sized buildings whilst still delivering thermal comfort. For hot climates, the benefit of utilising the waste heat emitted from an engine unit to power a thermally driven cooling device provides scope to utilise an otherwise wasted energy stream. However, in smaller sized residential buildings, the relatively low and intermittent energy demand coupled with high capital costs, has stifled the uptake of the technology - although the potential for substantial energy savings exists. Moreover, it is very common for home owners in hot climates to opt for other energy-saving devices such as solar water heaters (SWH), which would tend to reduce further the possible demand for space and water heating, possibly making the simultaneous use of both micro-trigeneration and SWH unfeasible. This paper compares the performance of a residential micro-trigeneration system to a hybrid micro-trigeneration/SWH system. The performance of both systems was simulated using a whole building simulation tool run at a high time resolution. The results obtained were then used to quantify the energetic and environmental performance of both systems; and also to assess their financial viability against the effect of varying fuel prices, electricity tariffs and a varying Feed-in Tariff (FIT). Results show that whereas the solar aided micro-trigeneration system obtains an overall higher (though marginal) energetic and environmental performance, the financial performance for the same fiscal parameters (fuel prices and electricity tariffs) deteriorates. Moreover FIT, plays an important role in the financial feasibility of the system

Energetic, environmental and economic modeling of a solar-assisted residential micro-trigeneration system in a Mediterranean climate

Reducing energy consumption in buildings has become a priority for most countries. However, designing energy-efficient buildings is not a straightforward task - the increasing demand for high comfort standards, provided by conventional ‘energy-hungry’ cooling and heating devices conflicts with the need for demand reduction. Trigeneration, the simultaneous production of electricity, cooling and heating is often viewed as a means of improving energy-efficiency in large and medium sized buildings whilst still delivering thermal comfort. For hot climates, the benefit of utilising the waste heat emitted from an engine unit to power a thermally driven cooling device provides scope to utilise an otherwise wasted energy stream. However, in smaller sized residential buildings, the relatively low and intermittent energy demand coupled with high capital costs, has stifled the uptake of the technology - although the potential for substantial energy savings exists. Moreover, it is very common for home owners in hot climates to opt for other energy-saving devices such as solar water heaters (SWH), which would tend to reduce further the possible demand for space and water heating, possibly making the simultaneous use of both micro-trigeneration and SWH unfeasible. This paper compares the performance of a residential micro-trigeneration system to a hybrid micro-trigeneration/SWH system. The performance of both systems was simulated using a whole building simulation tool run at a high time resolution. The results obtained were then used to quanti fy the energetic and environmental performance of both systems; and also to assess their financial viability against the effect of varying fuel prices, electricity tariffs and a varying Feed-in Tariff (FIT). Results show that whereas the solar aided micro-trigeneration system obtains an overall higher (though marginal) energetic and environmental performance, the financial performance for the same fiscal parameters (fuel prices and electricity tariffs) deteriorates. Moreover FIT, plays an important role in the financial feasibility of the system.peer-reviewe

Engineering adaptive user interfaces using monitoring-oriented programming

User interfaces which adapt based on usage patterns, for example based on frequency of use of certain features, have been proposed as a means of limiting the complexity of the user interface without specialising it unnecessarily to particular user profiles. However, from a software engineering perspective, adaptive user interfaces pose a challenge in code structuring, and separation of the different layers of user interface and application state and logic can introduce interdependencies which make software development and maintenance more challenging. In this paper we explore the use of monitoring-oriented programming to add adaptive features to user interfaces, an approach which has been touted as a means of separating certain layers of logic from the main system. We evaluate the approach both using standard software engineering measures and also through a user acceptance experiment - by having a number of developers use the proposed approach to add adaptation logic to an existing application.peer-reviewe

Viewpoints : What can agile methods bring to high-integrity software development?

Considering the issues and opportunities raised by Agile practices in the development of high-integrity software

The Lattice and Simplex Structure of States on Pseudo Effect Algebras

We study states, measures, and signed measures on pseudo effect algebras with some kind of the Riesz Decomposition Property, (RDP). We show that the set of all Jordan signed measures is always an Abelian Dedekind complete $\ell$-group. Therefore, the state space of the pseudo effect algebra with (RDP) is either empty or a nonempty Choquet simplex or even a Bauer simplex. This will allow represent states on pseudo effect algebras by standard integrals

Smearing of Observables and Spectral Measures on Quantum Structures

An observable on a quantum structure is any $\sigma$-homomorphism of quantum structures from the Borel $\sigma$-algebra of the real line into the quantum structure which is in our case a monotone $\sigma$-complete effect algebras with the Riesz Decomposition Property. We show that every observable is a smearing of a sharp observable which takes values from a Boolean $\sigma$-subalgebra of the effect algebra, and we prove that for every element of the effect algebra there is its spectral measure

Genetic structure of Tetraclinis articulata, an endangered conifer of the western Mediterranean basin

Tetraclinis articulata (Vahl) Masters is a tree distributed throughout the western Mediterranean basin. It is included in the IUCN (International Union for Conservation of Nature) red list, and protected by law in several of the countries where it grows. In this study we examined the genetic diversity and genetic structure of 14 populations of T. articulata in its whole geographic range using ISSR (inter simple sequence repeat) markers. T. articulata showed moderate genetic diversity at intrapopulation level and high genetic differentiation. The distribution of genetic diversity among populations did not exhibit a linear pattern related to geographic distances, since all analyses (principal coordinate analysis, Unweighted pair group method with arithmetic mean dendrogram and Bayesian structure analysis) revealed that spanish population grouped with Malta and Tunisia populations. Although it is possible that T. articulata earlier was natural in Southeast Spain, results suggest that the current population has been reintroduced into the Iberian Peninsula in historical times, due to its utility in mining and building. In addition, results could be used to propose management guidelines for the conservation of T. articulata.peer-reviewe

The Malta cistern mapping project : expedition II

This paper documents the second of two archeological expeditions that employed several underwater robot mapping and localization techniques. The goal of this project is to explore and map ancient cisterns located on the islands of Malta and Gozo. Dating back to 300 B.C., the cisterns of interest acted as water storage systems for fortresses, private homes, and churches. They often consisted of several connected chambers, still containing water. A Remotely Operated Vehicle (ROV), was deployed into cisterns to obtain video and sonar images. Using a variety of sonar based mapping techniques, two-dimensional maps of 18 different cisterns were created.peer-reviewe

Toqol ta’ delli

Ġabra ta’ poeżiji u proża li tinkludi: Il-ballata tal-belt ta’ J. P. Vassallo – Lil P. Dwardu Fenech ta’ Spiro Buhagiar – Għanja lill-ħemda ta’ Alexander Pope bi traduzzjoni ta’ Dwardu Zarb – Non omnis moriar ta’ Dwardu Zarb – Lil John F. Kennedy ta’ Alfred Massa – Il-lejla t-toroq ta’ Oliver Friggieri – Jum ta’ Rożi ta’ Stanley Mangion – It-toqol ta’ delli ta’ Karmenu Ellul Galea.peer-reviewe