A Second Replicated Quantitative Analysis of Fault Distributions in Complex Software Systems

Background. Software engineering is in search for general principles that apply across contexts, for example to help guide software quality assurance. Fenton and Ohlsson presented such observations on fault distributions, which have been replicated once. Objectives.We intend to replicate their study a second time in a new environment. Method.We conducted a close replication, collecting defect data from five consecutive releases of a large software system in the telecommunications domain, and conducted the same analysis as in the original study. Results. The replication confirms results on un-evenly distributed faults over modules, and that fault proneness distribution persist over test phases. Size measures are not useful as predictors of fault proneness, while fault densities are of the same order of magnitude across releases and contexts. Conclusions. This replication confirms that the un-even distribution of defects motivates un-even distribution of quality assurance efforts, although predictors for such distribution of efforts are not sufficiently precise

Integration and Deployment of Cloud-Based Assistance System in Pharaon Large Scale Pilots—Experiences and Lessons Learned

The EU project Pharaon aims to support older European adults by integrating digital services, tools, interoperable open platforms, and devices. One of the objectives is to validate the integrated solutions in large-scale pilots. The integration of mature solutions and existing systems is one of the preconditions for the successful realization of the different aims of the pilots. One such solution is an intelligent, privacy-aware home-care assistance system, SmartHabits. After briefly introducing the Pharaon and SmartHabits, the authors propose different Pharaon models in the Ambient/Active Assisted Living (AAL) domain, namely the Pharaon conceptual model, Pharaon reference logical architecture view, AAL ecosystem model, meta AAL ecosystem model, and Pharaon ecosystem and governance models. Building on the proposed models, the authors provide details of the holistic integration and deployment process of the SmartHabits system into the Pharaon ecosystem. Both technical and supporting integration challenges and activities are discussed. Technical activities, including syntactic and semantic integration and securing the transfer of the Pharaon sensitive data, are among the priorities. Supporting activities include achieving legal and regulatory compliance, device procurement, and use-case co-designing in COVID-19 conditions

Quantitative analysis of unit verification as predictor in large scale software enginering

Unit verification, including software inspections and unit tests, is usually the first code verification phase in the software development process. However, principles of unit verification are weakly explored, mostly due to the lack of data, since unit verification data are rarely systematically collected and only a few studies have been published with such data from industry. Therefore, we explore the theory of fault distributions, originating in the quantitative analysis by Fenton and Ohlsson, in the weakly explored context of unit verification in large-scale software development. We conduct a quantitative case study on a sequence of four development projects on consecutive releases of the same complex software product line system for telecommunication exchanges. We replicate the operationalization from earlier studies, analyzed hypotheses related to the Pareto principle of fault distribution, persistence of faults, effects of module size, and quality in terms of fault densities, however, now from the perspective of unit verification. The patterns in unit verification results resemble those of later verification phases, e.g., regarding the Pareto principle, and may thus be used for prediction and planning purposes. Using unit verification results as predictors may improve the quality and efficiency of software verification

Reverse breakdown and light-emission patterns studied in Si PureB SPADs

The relationship between light-emission patterns from silicon avalanche-mode light-emitting diodes (AMLEDs), and avalanche breakdown was investigated using photodiodes fabricated in pure boron (PureB) technology. The quality of the diodes ranged from high-quality, low dark-current devices with abrupt breakdown characteristics that were suitable for operation as single-photon avalanche diodes (SPADs), to diodes with gradually increasing reverse currents before actual breakdown. The reverse I-V characteristics were measured and correlated to light-emission data obtained simultaneously using a PureB photodetector, and inspected using a camera with which distinct emission patterns could be identified. When increasing the voltage far past breakdown, light emission invariably becomes dominant at the photodiode periphery. Based on the examination of a large variety of anode geometries, it is concluded that the most efficient light emission per consumed power is achieved with defect-free narrow-anode diodes that also are applicable as low-dark-count-rate SPADs

Impact of ultra-thin-layer material parameters on the suppression of carrier injection in rectifying junctions formed by interfacial charge layers

Pure amorphous boron (PureB) deposition on Si is used to fabricate ultrashallow low-saturation-current p+n-like diodes even at process temperatures where the boron is not expected to diffuse into the bulk Si. It has been proposed that the bonding of the B atoms to the Si creates a monolayer of fixed negative charge that attracts holes to the interface. In this paper, an investigation using semiconductor simulation tools is performed starting from an all-Si test structure where suppression of electron injection from an n-Si bulk was achieved by introducing a large concentration of negative fixed charge that attracts holes to the interface between a thin-film top-layer and the bulk. This introduces a barrier which lowers the electron saturation current density of the simulated diode to become comparable to or lower than the saturation current density of holes injected into the bulk. The material properties of the top-layer such as electron mobility and tunneling mass, bandgap and electron affinity are individually varied from default Si-values to values typical for amorphous boron layers indicating that a critical concentration of negative fixed charge is always needed for suppression of the electron injection