An Evaluation of Aspect-Oriented Programming as a Product Line Implementation Technology

Abstract. A systematic approach for implementing software product lines is more than just a selection of techniques. Its selection should be based on a systematic analysis of technical requirements and constraints, as well as of the types of variabilities, which occur in a particular application domain and are relevant for the planned product line (PL). In addition, each technique should provide a set of guidelines and criteria that support developers in applying the techniques in a systematic and unified way. This paper presents a case study that was performed to evaluate aspect-oriented programming (AOP) as a PL implementation technology. The systematical evaluation is organized along a general evaluation schema for PL implementation technologies.

Model-driven development of particle system families

Ambient-intelligence systems are characterized by a shift away from desktop computers to a variety of devices, which are unobtrusively embedded in the user environment. The usage of small computing nodes (particles) is one of the most efficient ways of their implementation. Such nodes are often installed in different appliances within an Ambient-intelligence system. In each case there is a joint particle infrastructure, which is reused as-is, but there are varying sensors, actuators and application logic deployed with the particle. This leads to a significant amount of software variability developers are confronted with. The combination of this variability with the complexity of the particle implementation burdens software development activities considerably. In this paper an approach is proposed that reduces the effort of these activities by bringing together model-driven development with product line engineering

A Concrete Method for Developing and Applying Product Line Architectures

Software development organizations are often deterred from introducing product line architectures by the lack of simple, ready-to-use methods for developing and applying them. The well-known, published product-line-engineering methods tend to focus on the early stages of the software life cycle and address product line issues at a high-level of abstraction. Connecting product-line concepts with established implementation technologies is thus largely left to the user. This paper introduces a method, known as the KobrA method, which addresses this problem by enabling product line concerns to be coupled with regular (non-product line) architectural artifacts, and thus introduced incrementally. By explaining how the method can be understood as a concrete instantiation of the well-established PuLSE-DSSA product-line architecture approach, the paper clarifies the product line features of the KobrA method and illustrates how they can be used in tandem with established, general-purpose product line methods

Intensity measures, fragility analysis and dimensionality reduction of rocking under far-field ground motions

Problems for which it is impossible to make a precise causal prediction are commonly tackled with statistical analysis. Although fairly simple, the problem of a rocking block on a rigid base subjected to seismic excitation exhibits a fascinating, complex response, making it extremely difficult to validate numerical models against experimental results, thus calling for a statistical approach. In this context, this paper statistically studies the rocking behaviour of rigid blocks, excited by synthetic far-field ground motions. A total of 50 million analyses are performed, considering rocking blocks of height ranging from 1 to 20 m and slenderness angle ranging from 0.1 to 0.35 rad. The results are used to explore the performance of different ground motion intensity measures (IMs), in terms of their ability to predict the maximum rocking rotation. By comparing the efficiency, sufficiency and proficiency of the IMs, it is found that the peak ground velocity (PGV) performs optimally. Then, fragility curves are constructed using different IMs, concluding again that the PGV is the most efficient IM. Impressively, the fragility curves for different block sizes collapse to a single curve, if a non-dimensional IM that involves PGV and the block geometry is used. Finally, the results produced on the basis of far-field synthetic motions are compared to results based on recorded ground motions.ISSN:0098-8847ISSN:1096-984

Robustness of simplified analysis methods for rocking structures on compliant soil

Recognizing the beneficial effect of nonlinear soil-foundation response has led to a novel design concept, termed 'rocking isolation'. The analysis and design of such rocking structures require nonlinear dynamic time history analyses. Analyzing the entire soil-foundation-structure system is computationally demanding, impeding the application of rocking isolation in practice. Therefore, there is an urgent need to develop efficient simplified analysis methods. This paper assesses the robustness of two simplified analysis methods, using (i) a nonlinear and (ii) a bilinear rocking stiffness combined with linear viscous damping. The robustness of the simplified methods is assessed by (i) one-to-one comparison with a benchmark finite element (FE) analysis using a selection of ground motions and (ii) statistical comparison of probability distributions of response quantities, which characterize the time history response of rocking systems. A bridge pier (assumed rigid) supported on a square foundation, lying on a stiff clay stratum, is used as an illustrative example. Nonlinear dynamic FE time history analysis serves as a benchmark. Both methods yield reasonably accurate predictions of the maximum rotation theta(max). Their stochastic comparison with respect to the empirical cumulative distribution function of theta(max)reveals that the nonlinear and the bilinear methods are not biased. Thus, both can be used to estimate probabilities of exceeding a certain threshold value of theta.Developed in this paper, the bilinear method is much easier to calibrate than the nonlinear, offering similar performance. (© 2020 John Wiley & Sons).ISSN:0098-8847ISSN:1096-984

Comparative Assessment of Two Rocking Isolation Techniques for a Motorway Overpass Bridge

Rocking isolation of structures is evolving as an alternative design concept in earthquake engineering. The present paper investigates the seismic performance of an actual overpass bridge of the Attiki Odos motorway (Athens, Greece), employing two different concepts of rocking isolation: (a) rocking of the piers on the foundation (rocking piers); and (b) rocking of the pier and foundation assembly (rocking footings) on the soil. The examined bridge is an asymmetric 5-span system having a continuous deck and founded on surface foundations on a deep clay layer. The seismic performance of the two rocking-isolated bridges is comparatively assessed to the existing bridge, which is conventionally designed according to current seismic design codes. To that end, 3D numerical models of the bridge–foundation–abutment–soil system are developed, and both static pushover and non-linear dynamic time history analyses are performed. For the latter, an ensemble of 20 records (10 ground motions of 2 perpendicular components each) that exceed the design level are selected. The conventional system collapses in 5/10 of the (intentionally severe) examined seismic excitations. The rocking piers design alternative survives in 8/10 of the cases examined, with negligible residual deformations. The safety margins of the rocking footings design concept are even larger, as it survives in all cases examined. Both rocking isolation concepts are proven to offer increased levels of seismic resilience, reducing the probability of collapse and the degree of structural damage. Nevertheless, in the rocking piers design alternative high stress concentrations at the rotation pole (pier base) are developed, indicating the need for a special design of the pier ends. This is not the case for the rocking footings concept, which however is subject to increased residual settlements but no residual rotations