Representing the behaviour of software projects using multi-dimensional timelines

Original article can be found at: http://www.sciencedirect.com/science/journal/09505849 Copyright Elsevier B.V.Context: There are few empirical studies in the empirical software engineering research community that describe software projects, at the level of the project, as they progress over time. Objective: To investigate how to coherently represent a large volume of qualitative and quantitative data on a range of project-level attributes as those attributes change over time. Method: Develop a modelling technique, multi-dimensional timelines (MDTs) and undertake a preliminary appraisal of the technique using examples from a longitudinal case study of a project at IBM Hursley Park. Results: MDTs can represent project-level attributes as they change over time, provided these attributes, and the empirical data about them, can be located in time (an analytical requirement) and can be represented in terms of the simple geometrical structures of points, lines and planes (a graphical requirement). Changes in attributes are documented at the point in time at which the change occurs. There are a number of ways in which an attribute can be represented on the MDT: as a quantitative time series, as an event, as an event with label containing complex qualitative information, or as a schedule. The MDT technique is currently not capable of representing relationships between different attributes e.g. a causal relationship. Conclusion: The initial appraisal of MDTs is encouraging, but further work is needed on the development of the MDT technique and on its evaluation.Peer reviewe

Resolution of simple singularities yielding particle symmetries in a space-time

A finite subgroup of the conformal group SL(2,C) can be related to invariant polynomials on a hypersurface in C^3. The latter then carries a simple singularity, which resolves by a finite iteration of basic cycles of deprojections. The homological intersection graph of this cycles is the Dynkin graph of an ADE Lie group. The deformation of the simple singularity corresponds to ADE symmetry breaking. A 3+1-dimensional topological model of observation is constructed, transforming consistently under SL(2,C), as an evolving 3-dimensional system of world tubes, which connect ``possible points of observation". The existence of an initial singularity for the 4-dimensional space-time is related to its global topological structure. Associating the geometry of ADE singularities to the vertex structure of the topological model puts forward the conjecture on a likewise relation of inner symmetries of elementary particles to local space-time structure.Comment: 16 pages, LaTe

A simple microcontroller based digital lock-in amplifier for the detection of low level optical signals

Traditionally digital lock-in amplifiers sample the input signal at a rate much higher than the lock-in reference frequency and perform the lock-in algorithm with high-speed processors. We present a small and simple digital lock-in amplifier that uses a 20 bit current integrating analogue-to-digital converter interfaced to a microcontroller. The sample rate is set to twice the reference frequency placing the sampled lock-in signal at the Niquest frequency allowing the lock-in procedure to be performed with one simple algorithm. This algorithm consists of a spectral inversion technique integrated into a highly optimised low-pass filter. We demonstrate a system with a dynamic range of 103dB recovering signals up to 85dB below the interference

Algebraic Quantum Theory on Manifolds: A Haag-Kastler Setting for Quantum Geometry

Motivated by the invariance of current representations of quantum gravity under diffeomorphisms much more general than isometries, the Haag-Kastler setting is extended to manifolds without metric background structure. First, the causal structure on a differentiable manifold M of arbitrary dimension (d+1>2) can be defined in purely topological terms, via cones (C-causality). Then, the general structure of a net of C*-algebras on a manifold M and its causal properties required for an algebraic quantum field theory can be described as an extension of the Haag-Kastler axiomatic framework. An important application is given with quantum geometry on a spatial slice within the causally exterior region of a topological horizon H, resulting in a net of Weyl algebras for states with an infinite number of intersection points of edges and transversal (d-1)-faces within any neighbourhood of the spatial boundary S^2.Comment: 15 pages, Latex; v2: several corrections, in particular in def. 1 and in sec.

Re-planning for a successful project schedule

Time-to-market or project duration has increasing significance for commercial software development. We report on a longitudinal study of a project at IBM Hursley Park. The focus of this study was schedule behaviour; however, we explored a range of related factors, including planned versus actual progress, resource allocation and functionality delivered. In the course of the 12-month study, evidence was collected from eight interviews, 49 project meetings, a number of project documents and a feedback workshop. The project leader considered the project to be a success, not only in terms of satisfying resource and schedule objectives, but also in the marketplace. Whilst many of the originally planned external commitments were met, it is clear that the project did not adhere to its original (detailed) plan and indeed there were no less than seven re-plans. These re-plans were mainly in response to mis-estimates in the original plan, rather than in response to the introduction of additional requirements (of which there were several) or problems with external dependencies. Furthermore, these re-plans suggest a distinction between the nature of the initial planning process and the nature of the re-planning process during the project. Attention is also directed at the implications these re-plans have for software metrics and cost estimation researc