A framework for the simulation of structural software evolution

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2008 ACM.As functionality is added to an aging piece of software, its original design and structure will tend to erode. This can lead to high coupling, low cohesion and other undesirable effects associated with spaghetti architectures. The underlying forces that cause such degradation have been the subject of much research. However, progress in this field is slow, as its complexity makes it difficult to isolate the causal flows leading to these effects. This is further complicated by the difficulty of generating enough empirical data, in sufficient quantity, and attributing such data to specific points in the causal chain. This article describes a framework for simulating the structural evolution of software. A complete simulation model is built by incrementally adding modules to the framework, each of which contributes an individual evolutionary effect. These effects are then combined to form a multifaceted simulation that evolves a fictitious code base in a manner approximating real-world behavior. We describe the underlying principles and structures of our framework from a theoretical and user perspective; a validation of a simple set of evolutionary parameters is then provided and three empirical software studies generated from open-source software (OSS) are used to support claims and generated results. The research illustrates how simulation can be used to investigate a complex and under-researched area of the development cycle. It also shows the value of incorporating certain human traits into a simulation—factors that, in real-world system development, can significantly influence evolutionary structures

Overview The Topic Specific Search Engine

Version 0.1 <DRAFT> This paper presents a model for creating an accurate topic specific search engine through a focussed (vertical) crawling mechanism. The system is designed to run on limited physical resources (Most topics specific searches can be hosted using two well built home PCs). The implementation method is general but it is assumed that it would leverage from an open source search engine base such as Nutch. The application is comprised of four parts; a crawler (spider), an indexer, a ranking mechanism (pre-emptive or lazy) and a user interface. The implementation presented here has the following extra features: 1. Crawling commences from a set of seed URLs. The seed set is generated by feeding positive and negative search keywords into a commercial search engine and using the resulting URL’s as the seed list. The keyword set input into the search engine is defined by an expert user (this can be aided through data mining of positive and negative sample pages). 2. The crawling process does not cover the whole web. Instead it starts from the seed URL’s created in (1) and crawls connected pages so long as they continue to be considered relevant. 3. Each page that is crawled is analysed for its relevance w.r.t. the search topic. This relevance value is based on both the initial keyword set and the relevance of the page’s locality

Collision induced dissociation (CID) to probe the outer sphere coordination chemistry of bis-salicylaldoximate complexes

Ligand-ligand interactions in the outer coordination sphere make an important contribution to the effects of 3-substituents on the stabilities of anionic Cu(II) salicylaldoximato complexes [CuL(L-H)](-). When substituents contain a different number of bonds the interpretation of CID tandem mass spectrometry must take into account the ability of ions to redistribute energy acquired in collisions within different numbers of vibrational modes