111,864 research outputs found
Many-objective optimization of non-functional attributes based on refactoring of software models
No full textContext: Software quality estimation is a challenging and time-consuming activity, and models are crucial to face the complexity of such activity on modern software applications. In this context, software refactoring is a crucial activity within development life-cycles where requirements and functionalities rapidly evolve. Objective: One main challenge is that the improvement of distinctive quality attributes may require contrasting refactoring actions on software, as for trade-off between performance and reliability (or other non-functional attributes). In such cases, multi-objective optimization can provide the designer with a wider view on these trade-offs and, consequently, can lead to identify suitable refactoring actions that take into account independent or even competing objectives. Method: In this paper, we present an approach that exploits the NSGA-II as the genetic algorithm to search optimal Pareto frontiers for software refactoring while considering many objectives. We consider performance and reliability variations of a model alternative with respect to an initial model, the amount of performance antipatterns detected on the model alternative, and the architectural distance, which quantifies the effort to obtain a model alternative from the initial one. Results: We applied our approach on two case studies: a Train Ticket Booking Service, and CoCoME. We observed that our approach is able to improve performance (by up to 42%) while preserving or even improving the reliability (by up to 32%) of generated model alternatives. We also observed that there exists an order of preference of refactoring actions among model alternatives. Conclusion: Based on our analysis, we can state that performance antipatterns confirmed their ability to improve performance of a subject model in the context of many-objective optimization. In addition, the metric that we adopted for the architectural distance seems to be suitable for estimating the refactoring effort
HEPSYCODE-RT: a Real-Time Extension for an ESL HW/SW Co-Design Methodology
No full textThis work(1) focuses on the definition of a methodology for handling embedded real-time applications, starting from an existing HW/SW co-design methodology able to support the design of dedicated heterogeneous parallel systems. The state-of-the-art related to similar tools and methodologies is presented and the reference framework with the proposed extension to the real-time world is introduced. A case study is then described to show a design space exploration able to consider such an extension
An early-stage statement-level metric for energy characterization of embedded processors
Full text linkAn early-stage statement-level metric for energy characterization of embedded processors
No full textThis work presents an early stage statement-level metric for energy characterization of embedded processors. Definition and the framework for metric evaluation are provided. In particular, such a metric is based on an existing assembly-level analysis and some profiling activities performed on a given C benchmark, and it is related to the average energy consumption of a generic C statement, for a given target processor. Its evaluation is performed with a one-time effort and, once available, it can be used to rapidly estimate the energy consumption of a given C function for all the considered processors. Two reference embedded processors are then considered in order to show an example of usage of the proposed metric and framework. (C) 2020 The Author(s). Published by Elsevier B.V
Software Model Refactoring Driven by Performance Antipattern Detection
No full textThe satisfaction of ever more stringent performance requirements is one of the main reasons for software evolution. However, determining the primary causes of performance degradation is generally challenging, as they may depend on the joint combination of multiple factors (e.g., workload, software deployment, hardware utilization). With the increasing complexity of software systems, classical bottleneck analysis seems to show limitations in capturing complex performance problems. Hence, in the last decade, the detection of performance antipatterns has gained momentum as an effective way to identify performance degradation causes. In this tool paper we introduce PADRE (Performance Antipattern Detection and REfactoring), a tool for: (i) detecting performance antipattern in UML models, and (ii) refactoring models with the aim of removing the detected antipatterns. PADRE has been implemented within Epsilon, which is an open-source platform for model-driven engineering, and it grounds on a methodology that allows performance antipattern detection and refactoring within the same implementation context
Statement-Level Timing Estimation for Embedded System Design Using Machine Learning Techniques
No full textDuring the initial design phases of an embedded system, the ability to support designers using metrics, obtained through a preliminary analysis, is of fundamental importance. Knowing which initial parameters of the embedded system (HW or SW) influence such metrics is even more important. The main characteristic of an embedded system that typically designers need to measure is the embedded SW (i.e., functions) execution time, used to describe the final system's performance (i.e., timing performance metric). The evaluation of such a metric is often a critical task, relying on several different techniques at different abstraction levels. Furthermore, in the era of Big Data, the use of Machine Learning methods can be a valid alternative to the classic methods used to evaluate or estimate metrics for temporal performance. In such a context, this paper describes a framework, based on the use of Machine Learning methods, to calculate a statement-level embedded software timing performance metric. Results are compared with those obtained with different approaches. They show that the proposed method improves the estimation accuracy for specific processor classes while also reducing estimation time
Orazio, Persio e lo stoico cenare (Pers. 5,42)
No full textL'articolo propone una nuova interpretazione di Pers. 5,42: sia la lingua (l'uso del verbo 'decerpo' e il comune significato di 'epulae'), sia la tecnica imitativa di Persio nei cofronti di Orazio, suggeriscono di interpretare 'epulis' come ablativo separativo. Questa esegesi è assai meglio consonante con la forma e il contenuto della satira V (un intenso encomio del maestro stoico) e soprattutto con il modo in cui generalmente Persio si rapporta al suo più importante predecessore
An ESL Methodology for HW/SW Co-Design of Monitorable Embedded Systems: The 'Design for Monitorability' Project-Work-in-Progress
No full textIncorporation and channel formation of human calcitonin in phosphatydilcholine planar membranes as a function of pH
Full text linkHuman calcitonin (hCt) is a 32 amino acid peptide contributing to calcium homeostasis.
CD studies indicate that hCt has a lower propensity to form secondary structures than salmon
calcitonin (sCt) (Epand et al., 1985, Int. J. Pept. Protein Res., 25, 105). This can cause
fibrillation, which is critically influenced by pH, as Lys 18 protonation and Asp 15 deprotonation
occur at different pH values (Kamihira et al., 2000, Protein Sci., 9, 867).
However, hCt forms channels in planar lipid membranes of palmitoyloleoylphosphatidylcholine:
dioleoylphosphatidylglycerol (85:15) at low concentrations or at high applied voltages (Stipani et
al., 2001, Biophysical J., 81, 3332), although the biological relevance of this action has not yet
been demonstrated. On the other hand, hCt fails to interact with POPC or egg
phosphatidylcholine (Epand et al., 1983, Biochemistry, 22, 504), nor does it form channels in
palmitoylphosphatidylcholine planar membranes (Stipani et al., 2001, Biophysical J., 81, 3332).
We have studied the interaction of hCt with planar membranes made up of
palmitoyloleoylphosphatidylcholine at pH 7, pH 3.8 and pH 3.12, in a KCl (1M) medium. Our
results show that hCt easily incorporates into membranes and forms channels at low pH with a
central conductance similar to that obtained in
palmitoyloleoylphosphatidylcholine:dioleoylphosphatidylglycerol membranes. Furthermore, the
time lag between the addition of hCt and the first channel appearance is dramatically reduced,
while the number of channels/min increases substantially. At pH 7, even when left for as long as
24 hours in the bathing medium, hCt failed to incorporate and form channels in the membrane.
These results confirm that alpha-helical conformation is the main driving force for peptide
incorporation into membranes, thus preventing molecules from forming fibrils
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