Measuring architectural adaptability in i* models

Developing adaptable systems is still a big challenge in software engineering. Different reference architectures and systematic approaches have been proposed to address this challenge. Several of these approaches are based on goal models, given their suitability to express and reason on alternative behaviors. In this paper we intend to provide a basis for comparing architectures described in goal-based models in regard to their adaptability. This way, different approaches to improve adaptability may be compared based on the resulting architectures. To do so we mapped two adaptability metrics onto i* models and developed guidelines to define the adaptability of individual elements, based on the extra information provided by i* models. We applied these metrics in a healthcare system to illustrate the comparison of architectures.Peer ReviewedPostprint (published version

From i* models to service oriented architecture models

Requirements engineering and architectural design are key activities for successful development of software systems. Specifically in the service-oriented development systems there is a gap between the requirements description and architecture design and assessment. This article presents a systematic process for systematically deriving service-oriented architecture from goal-oriented models. This process allows generate candidate architectures based on i* models and helps architects to select a solution using services oriented patterns for both services and components levels. The process is exemplified by applying it in a synthesis metadata and assembly learning objects system.Peer ReviewedPostprint (author’s final draft

Towards anticipating requirements changes through studies of the future

© 2011 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Whilst it is considered a good practice to focus Requirements Engineering on current stakeholder needs, the high costs implied by requirements changes and the emergence of the Autonomic Computing paradigm raised the need for dealing with issues that are not currently requirements but that may come to be in the future. This work shows how foresight techniques can be used for requirements elicitation, and discusses the impacts of studying the future to that requirements engineering activity. In particular, it addresses the use of the Futures Wheel method to enrich goal models.Peer ReviewedPostprint (author's final draft

Relationship of Physical Activity and Sleep Duration with Self-Concept, Mediterranean Diet and Problematic Videogame Use in Children: Structural Equation Analysis as a Function of Gender

Engagement in physical activity and sleep duration are crucial to the adequate psychosocial and healthy development of children. Thus, the aim of this study was to develop an explanatory model of the relationships of physical activity and sleep duration with self-concept, Mediterranean diet and problematic use of videogames. Accordingly, a structural model was contrasted by means of a multi-group analysis according to gender. A non-experimental study was conducted with a descriptive, cross-sectional design for a sample of 1154 students aged 11-12 years (M = 11.41 +/- 0.49). An ad hoc questionnaire was used to record sociodemographic and physical-health attributes (physical activity time and sleep). Adherence to a Mediterranean diet was assessed using the KIDMED questionnaire, self-concept was assessed using "self-concept form-5" (AF-5) and problematic videogame use was assessed using the "Video Game-Related Experiences Questionnaire". For data analysis, a multi-group structural equation analysis was performed. The results showed that physical activity was positively associated with self-concept, while sleep duration and self-concept were negatively related to problematic videogame use. In boys there was a direct effect of self-concept on sleep duration and adherence to the Mediterranean diet, while girls did not generate such differences. Although there is a negative association between physical activity and problematic videogame use in the theoretical model and in boys, girls showed a direct association between these factors. Finally, physical activity and sleep duration were directly related in boys and indirectly related in girls

Effects of buffer insertion on the average/peak power ratio in CMOS VLSI digital circuits

The buffer insertion has been a mechanism widely used to increase the performances of advanced VLSI digital circuits and systems. The driver or repeater used to this purpose has effect on the timing characteristics on the signal on the wire, as propagation delay, signal integrity, transition time, among others. The power concerns related to buffering have also received much attention, because of the low power requirements of modern integrated systems. In the same way, the buffer insertion has strong impact on the reliability of synchronous systems, since the suited distribution of clock requires reduced or controlled clock-skew, being the buffer and wire sizing, a crucial aspect. In a different way, buffer insertion has been also used to reduce noise generation, especially in heavily loaded nets, since the inclusion of buffers help to desynchronize signal transitions. However, the inclusion of buffers of inverters to improve one or more of these characteristics have often negative effect on another parameters, as it happens in the average and peak of supply current. Mainly, the inclusion of a buffer to reduce noise (peak power), via desynchronizing transitions, could introduce more dynamic consumption, but reducing the short-circuit current because of the increment of signal slope. Thus, the average/peak current optimization can be considered a design trade-off. In this paper, the mechanism to obtain an average/peak power optimization procedure are presented. Selected examples show the feasibility of minimizing switching noise with negligible impact on average power consumption.MEC TEC2004-01509 DOCJunta de Andalucía TIC2006-635 Project

A packing computational method relating fractal particle size distribution and void fraction in granular media

The study of granular systems is of great interest to many fields of science and technology. The packing of particles affects to the physical properties of the granular system. In particular, the crucial influence of particle size distribution (PSD) on the random packing structure increase the interest in relating both, either theoretically or by computational methods. A packing computational method is developed in order to estimate the void fraction corresponding to a fractal-like particle size distribution

Late-type members of young stellar kinematic groups - I. Single stars

This is the first paper of a series aimed at studying the properties of late-type members of young stellar kinematic groups. We concentrate our study on classical young moving groups such as the Local Association (Pleiades moving group, 20-150 Myr), IC 2391 supercluster (35 Myr), Ursa Major group (Sirius supercluster, 300 Myr), and Hyades supercluster (600 Myr), as well as on recently identified groups such as the Castor moving group (200 Myr). In this paper we compile a preliminary list of single late-type possible members of some of these young stellar kinematic groups. Stars are selected from previously established members of stellar kinematic groups based on photometric and kinematic properties as well as from candidates based on other criteria such as their level of chromospheric activity, rotation rate and lithium abundance. Precise measurements of proper motions and parallaxes taken from the Hipparcos Catalogue, as well as from the Tycho-2 Catalogue, and published radial velocity measurements are used to calculate the Galactic space motions (U, V W) and to apply Eggen's kinematic criteria in order to determine the membership of the selected stars to the different groups. Additional criteria using age-dating methods for late-type stars will be applied in forthcoming papers of this series. A further study of the list of stars compiled here could lead to a better understanding of the chromospheric activity and their age evolution, as well as of the star formation history in the solar neighbourhood. In addition, these stars are also potential search targets for direct imaging detection of substellar companions

Procedure for Technological Diagnosis of Oily Residuals Management in Cubans Distributed Generation Power Plants

In Cuba, more than 50 % of the electricity generation capacity is based on small-scale distributed power plants, which guarantee the energy supply-demand from fossil fuels. Several negative environmental impacts are associated with this, including contamination by oily residuals. The purpose was to diagnose oily residuals management in Cubans distributed generation power plants from a technological approach. Ten generating power plants from Cienfuegos territory were selected as a case study. A methodological procedure, supported in the general method of problem-solving was designed. The environmental audit was used as a fundamental tool for the verification of technical requirements regarding the containment, collection, evacuation, treatment, and final disposal of oily waste. For deployment of causes identified as evidence of auditory, failures modes and effects analysis (FMEA) were used. Hydrocarbon concentrations at sampling points in the external environment frequently exceeded the threshold. Hydrocarbon spills, clogging and waste load increased in the treatment system, were the most frequent failure modes and could manifest themselves from the occurrence of more than 150 causes. From this group, a set of common causes inherent to each power plant was identified. A package of corrective actions was designed, which constituted conceptual ideas for improving environmental performance. The procedure was generalized to other power plants in the country, contributing to sustainability in the generation of electricity in Cuba

Bioremediation of Hydrocarbon-Polluted Soil: Evaluation of Different Operative Parameters

The bioremediation of soils polluted with hydrocarbons demonstrated to be a simple and cheap technique, even if it needs a long time. The current paper shows the application of statistical analysis, based on two factors involved in the biological process at several levels. We focus on the Design of Experiments (DOE) to determine the number and kind of experimental runs, whereas the use of the categorical factors has not been widely exploited up to now. This method is especially useful to analyze factors with levels constituted by categories and define the interaction effects. Particularly, we focused on the statistical analysis of (1) experimental runs carried out at laboratory scale (test M, in microcosm), on soil polluted with diesel oil, and (2) bench scale runs (test B, in biopile), on refinery oil sludge mixed with industrial or agricultural biodegradable wastes. Finally, the main purpose was to identify the factor’s significance in both the tests and their potential interactions, by applying the analysis of variance (ANOVA). The results demonstrate the robustness of the statistical method and its quality, especially when at least one of the factors cannot be defined with a numerical value

The glutamine synthetase gene family in Populus

<p>Abstract</p> <p>Background</p> <p>Glutamine synthetase (GS; EC: 6.3.1.2, L-glutamate: ammonia ligase ADP-forming) is a key enzyme in ammonium assimilation and metabolism of higher plants. The current work was undertaken to develop a more comprehensive understanding of molecular and biochemical features of <it>GS </it>gene family in poplar, and to characterize the developmental regulation of <it>GS </it>expression in various tissues and at various times during the poplar perennial growth.</p> <p>Results</p> <p>The <it>GS </it>gene family consists of 8 different genes exhibiting all structural and regulatory elements consistent with their roles as functional genes. Our results indicate that the family members are organized in 4 groups of duplicated genes, 3 of which code for cytosolic GS isoforms (GS1) and 1 which codes for the choroplastic GS isoform (GS2). Our analysis shows that <it>Populus trichocarpa </it>is the first plant species in which it was observed the complete <it>GS </it>family duplicated. Detailed expression analyses have revealed specific spatial and seasonal patterns of <it>GS </it>expression in poplar. These data provide insights into the metabolic function of GS isoforms in poplar and pave the way for future functional studies.</p> <p>Conclusions</p> <p>Our data suggest that <it>GS </it>duplicates could have been retained in order to increase the amount of enzyme in a particular cell type. This possibility could contribute to the homeostasis of nitrogen metabolism in functions associated to changes in glutamine-derived metabolic products. The presence of duplicated <it>GS </it>genes in poplar could also contribute to diversification of the enzymatic properties for a particular GS isoform through the assembly of GS polypeptides into homo oligomeric and/or hetero oligomeric holoenzymes in specific cell types.</p