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Over the last few years, the analysis of seismic noise recorded by two dimensional arrays has been confirmed to be capable of deriving the subsoil shear-wave velocity structure down to several hundred meters depth. In fact, using just a few minutes of seismic noise recordings and combining this with the well known horizontal-to-vertical method, it has also been shown that it is possible to investigate the average one dimensional velocity structure below an array of stations in urban areas with a sufficient resolution to depths that would be prohibitive with active source array surveys, while in addition reducing the number of boreholes required to be drilled for site-effect analysis. However, the high cost of standard seismological instrumentation limits the number of sensors generally available for two-dimensional array measurements (i.e., of the order of 10), limiting the resolution in the estimated shear-wave velocity profiles. Therefore, new themes in site-effect estimation research by two-dimensional arrays involve the development and application of low-cost instrumentation, which potentially allows the performance of dense-array measurements, and the development of dedicated signal-analysis procedures for rapid and robust estimation of shear-wave velocity profiles. In this work, we present novel low-cost wireless instrumentation for dense two-dimensional ambient seismic noise array measurements that allows the real–time analysis of the surface-wavefield and the rapid estimation of the local shear-wave velocity structure for site response studies. We first introduce the general philosophy of the new system, as well as the hardware and software that forms the novel instrument, which we have tested in laboratory and field studies.

Today the syntax of many languages is defined by using context-free grammars. These syntax definitions suffer from a major drawback: grammars do not allow the definition of abstract, reusable concept definitions. Especially in families of related languages, where multiple languages often share the same concepts, this limitation leads to unnecessary reproduction of concept definitions and a missing shared base for these related languages. Metamodels can contain inheritance hierarchies of concepts; thus multiple specifications can reuse and refine existing shared concept definitions. Therefore we propose a method to develop metamodels from existing syntax definitions. We explain our method by applying it to SDL-2000. The method starts with a mapping from BNF grammars into simple preliminary metamodels. Then, by supplying a relation between elements of these simple metamodels and abstract concepts, these metamodels are automatically transformed into metamodels that use existing descriptions of abstract concepts and thus allow a shared basis of common abstract concepts definitions.

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Abstract. Existing model persistence frameworks either store models as a whole or object by object. Since most modeling tasks work with larger aggregates of a model, existing persistence frameworks either load too many objects or access many objects individually. We propose to persist a model broken into larger fragments. First, we assess the size of large models and describe typical usage patterns to show that most applications work with aggregates of model objects. Secondly, we provide an analytical framework to assess execution time gains for partially loading models fragmented with different granularity. Thirdly, we propose meta-model-based fragmentation that we implemented in an EMF based framework. Fourthly, we analyze our approach in comparison to other persistence frameworks (XMI, CDO, and Morsa) based on four common modeling tasks: create/modify, traverse, query, and partial loads. We show that there is no generally optimal fragmentation, that fragmentation can be achieved automatically and transparently, and that fragmentation provides considerable performance gains compared to other persistence strategies.

Rapid improvements in telemetry technology and the general decrease in communication costs have raised a growing interest in low-cost wireless sensing units. This is especially the case for structural monitoring purposes, where they are becoming a more valuable alternative to conventional wired monitoring system. The main advantages associated with the use of wireless sensing unit include a considerable decrease in installation costs, decentralization of data analysis, and the possibility of broadening the functional capabilities by exploiting the use, at the same time and place, of different sensors. In this work, the design of a low-cost wireless sensing unit able both to collect, analyze, store, and communicate data and estimated parameters is presented. The suitability of a network of these low-cost wireless instruments for monitoring the vibration characteristics and dynamic properties of strategic civil infrastructures is validated during a ambient vibration recording field test on the Fatih Sultan Mehmet Bridge in Istanbul, Turkey.

Abstract. This paper presents a method to describe the operational semantics of languages based on their meta-model. We combine the established high-level modelling languages MOF, OCL, and UML activities to create language models that cover abstract syntax, runtime configurations, and the behaviour of runtime elements. The method allows graphical and executable language models. These models are easy to read by humans and are formal enough to be processed in a generic model interpreter. We use Petri-nets as a running example to explain the method. The paper further proposes design patterns for common language concepts. The presented method was applied to the existing modelling language SDL to examine its applicability.

A new approach for earthquake early warning systems (EEWS) is presented that uses wireless, selforganizing mesh sensor networks. To develop the prototype of such IT infrastructures, we follow a modeldriven system development paradigm. Structure and behaviour models of network topologies in specific geographic regions are coupled with wave signal analysing algorithms, alarming protocols, convenient visualisations and earthquake data bases to form the basis for various simulation experiments ahead of system implementation and installation. The general objective of these studies is to test the functionality of an EEWS and to optimize it under the real-time, reliability and cost-depended requirements of potential end-users. For modelling a technology mix of SDL/ASN.1/UML/C++ is used to generate the code for different kind of simulators, and for the target platform (several node types). This approach is used for realizing a prototype EEWS developed within the EU project SAFER (Seismic Early Warning for Europe) in cooperation with the Geoforschungszentrum Potsdam (GFZ). The first operational area of that EEWS is preparation for Istanbul in a region threatened by strong earthquakes. The presented paper focuses on our adopted and developed tool-based modelling and data base techniques used in that project, that are general and flexible enough for addressing similar prototyping use cases of selforganizing sensor-based IT infrastructures.