Agent-based Simulation of Open Source Software Evolution

We present an agent-based simulation model of open source software (OSS). To our knowledge, this is the first model of OSS evolution that includes four significant factors: productivity limited by the complexity of software modules, the software's fitness for purpose, the motivation of developers, and the role of users in defining requirements. The model was evaluated by comparing the simulated results against four measures of software evolution (system size, proportion of highly complex modules, level of complexity control work, and distribution of changes) for four large OSS systems. The simulated results resembled all the observed data, including alternating periods of growth and stagnation. The fidelity of the model suggests that the factors included here have significant effects on the evolution of OSS systems

Relationship between size, effort, duration and number of contributors in large FLOSS projects

This contribution presents initial results in the study of the relationship between size, effort, duration and number of contributors in eleven evolving Free/Libre Open Source Software (FLOSS) projects, in the range from approx. 650,000 to 5,300,000 lines of code. Our initial motivation was to estimate how much effort is involved in achieving a large FLOSS system. Software cost estimation for proprietary projects has been an active area of study for many years. However, to our knowledge, no previous similar research has been conducted in FLOSS effort estimation. This research can help planning the evolution of future FLOSS projects and in comparing them with proprietary systems. Companies that are actively developing FLOSS may benefit from such estimates. Such estimates may also help to identify the productivity ’baseline’ for evaluating improvements in process, methods and tools for FLOSS evolution

Apuntes de 730211205-Mecánica Fundamental I

Escola Politécnica Superio

Empirical studies of open source evolution

Copyright @ 2008 Springer-VerlagThis chapter presents a sample of empirical studies of Open Source Software (OSS) evolution. According to these studies, the classical results from the studies of proprietary software evoltion, such as Lehman’s laws of software evolution, might need to be revised, if not fully, at least in part, to account for the OSS observations. The book chapter also summarises what appears to be the empirical status of each of Lehman’s laws with respect to OSS and highlights the threads to validity that frequently emerge in these empirical studies. The chapter also discusses related topics for further research

Formation and dynamics of structural defects in ion chains

Non-adiabatic crossing of symmetry breaking phase transitions results in formation of a domain structure and topological defects. The average density of domains depends on the quench rate of the phase transition. Kibble-Zurek mechanism predicts the scaling of the number of domains with quench rate. Phase transitions are ubiquitous in Nature and formation of domains and defects occurs in many different systems. One example of such system is Coulomb crystals of trapped ions, where structural defects can form as a result of symmetry breaking structural transitions between different crystal configurations. In the thesis, we investigate the Kibble-Zurek mechanism using the linear to zigzag structural phase transition in trapped ion Coulomb crystals. First, we analyse the equilibrium properties of crystals in the vicinity of the critical point of the linear to zigzag transition. Next, we show how to derive Kibble-Zurek scaling laws by transforming the equations of motion into a universal form. This mathematical derivation of the scaling laws is generalized for finite and inhomogeneous systems. Two experiments measuring the defect scaling in small trapped ion crystals are described, whose results agree with molecular dynamics simulations. In order to understand and predict defect dynamics we develop the technique for calculating the effective potential in which the defects move. Using this technique we show that heavy molecular ions stabilize the structural defects in zigzag chains and suggest a way of controlling kink motion using the application of electric fields. Finally, conclusions are drawn and possibilities for future work are suggested.Open Acces

Classification of Grey-Cinnamon (Chestnut) Soils with Nutrient Source of the Shamkirchay Reservoir and Analysis of Morphogenetic Diagnostic Indices

The mountain grey-cinnamon (chestnut) soils which are irrigated by the Shamkirchay water reservoir is formed mainly on the foothill, plain and partly on the mountainousborders and orographically on the northern east slope of the Little Caucasus are situated between 40039/ - 41000/ north latitude and 45050/ - 46020/ east longitude. The classification of mountain grey-cinnamon soils in the zone with 54263,74 ha on subtypes and analysis of the morphogenetic diagnostic indices has been given in the article. 7 subtypes of mountain grey-cinnamon soils are formed in the zone: separate morphological description of each subtype was analyzed in the article. At the same time, a modern state of the main physicochemical and fertility indices of the soils in the basin zone and information about the researches performed in the soils inside of the Shamkir, Goy-gol and Samukh borders have been presented. The diagnostic indices of the soil sections in the characteristic places, morphological description and agrochemical features of the soil profiles on subtypes and their analysis result were explanatory analyzed. Humus, total nitrogen, phosphorus and potassium, granulometric composition (sand, dust, silt and clay fractions) environment reaction of soil (pH) and calcareous (CaCO3) were fixed, statistically analyzed