Information systems development for contracting

The general principles of recording data flow within a construction organisation are considered in order to specify an integrated management information system. Recommendations for the initiation of a management information system are also made together with a range of possible objectives. structured systems development is suggested to build a logical model that shows the interrelationship of data processing. The need for interactive system is developed together with the requirement of a structured approach based on a selection of objectives. Finally a system for main contractor control and for directly employed resource control is proposed.     

An algorithm for generating solid elements in objects with holes

An algorithm for dividing an object with holes into solid elements for finite element preprocessing is presented. Since a tetrahedron can always be subdivided into prisms and cuboids, the approach of first dividing the given object into disjoint tetrahedra is taken.Objects without holes are dealt with first. Two mesh operators, each generating a single tetrahedron, are presented. In addition to the construction procedure, it is shown that they handle all objects without holes. The algorithm for objects with holes requires a third operator. In addition to showing the necessary and sufficient condition for applying such an operator, it is shown that it effectively reduces the number of holes in an object by one while yielding three tetrahedra. The algorithm which sequences the three operators thus reduces a given polyhedron to a single tetrahedron iteratively. Data structure requirements and update procedures are also given in this paper.     

Linear equality constraints in finite element approximation

The typical numerical problem associated with finite element approximations is a quadratic programming problem with linear equality constraints. When nodal variables are employed, the coefficient matrix of the constraint equations, [ A ], acquires a block-diagonal structure. The transformation from polynomial coefficients to nodal variables involves finding a basis for [ A ] and computing its inverse. Simultaneous satisfaction of completeness and C¹ (or higher) continuity requirements establishes linear relationships among the nodal variables and precludes inversion of the basis by exclusively element-level operations. Linear dependencies among the constraint equations and among the nodal variables can be evaluated by the simplex method. The computational procedure is outlined.     

Performance analysis of large systems

A hybrid analytic and experimental approach to the analysis of large systems is described. The approach is iterative under the assumption that a correct analysis will not be made first time. It is primarily aimed at the analysis of the performance effect of proposed changes prior to coding them. The requirement is for a fairly approximate analysis that is easy to make. The approach is illustrated by an experiment on a relational database system but we believe it to be applicable to many kinds of large systems. The different reasons for analysing performance of a system are discussed and then the ways of approaching the analysis, with an outline of our approach. The details of our approach are given, and illustrated by our experiment.     

Polymerisation resistant synthesis of methacrylamido phenylboronic acids

Acrylamido boronic acids are important building blocks for functional polymers but suffer from poor synthetic strategies and unwanted polymerisation. A two-step deprotection of pinacolato methacrylamido phenylene boronic esters to generate 2-, 3- and 4-methacrylamido phenylboronic acids in good yield and purity is reported. Boronic acid containing methacrylamido monomers are now available in good yields for incorporation into polymers.     

Prolog III

Prolog III is available from PrologIA Luminy, Case 919 13288, Marseille Cedex 09, France. Tel: +33 91 26 86 36. Prices (French francs): Sun 3, 70 000; Sparc 100 000; Mac Plus/SE 30 000; Mac SE 30/II38 000; IBM PC 386 38 000. Prices exclude VAT. Universities are entitled to a 60% discount and research centres to 30%. Systems are also available for HP9000 (series 300 and series 800), VAX and DECstation.     

A Classification System for Reliability Models

There has been little attempt to introduce a general classification system for reliability models analogous to those in other areas of applied probability, notably queueing systems. Thus there has been an unavoidable confusion in the literature and considerable unnecessary duplication of investigative effort. This paper argues the case for a classification system analogous to that in use for queues; identifies necessary features of such a system; and proposes a partial classification system. To be successful such a system must not only be a relatively convenient summary of diverse models, but must have the general support of the reliability community.     

Imaging Properties of a Positron Tomograph with 280 Bgo Crystals

The basic imaging properties of the Donner 280-BGO-Crystal positron tomograph were measured and compared with the same system when it was equipped with 280 NaI(T1) crystals. The NaI(T1) crystals were 8 mm × 30 mm × 50 mm deep, sealed in 10 mm wide stainless steel cans. The BGO crystals are 9.5 mm wide × 32 mm × 32 mm deep and as they are not hygroscopic do not require sealed cans. With a shielding gap of 3 cm (section thickness 1.7 cm FWHM) the sensitivity of the BGO system is 55,000 events per sec for 1 ?Ci per cm3 in a 20 cm cylinder of water, which is 2.3 times higher than the NaI(T1) system. For a 200 ?Ci/cm line source on the ring axis in a 20 cm diameter water cylinder, the BGO system records 86% of the scatter fraction and 66% of the accidental fraction of the NaI(T1) system. The lower light yield and poorer time resolution of BGO requires a wider coincidence timing window than NaI(T1); however, the ability to use full-energy pulse height selection with a 2.3-fold improvement in sensitivity results in an overall reduction in the fraction of accidental events recorded. The in-plane resolution of the BGO system is 9-10 mm FWHM within the central 30 cm diameter field, and the radial elongation at the edge of the field in the NaI(T1) system has been nearly eliminated.