Cognitive Profile of Students Who Enter Higher Education with an Indication of Dyslexia

For languages other than English there is a lack of empirical evidence about the cognitive profile of students entering higher education with a diagnosis of dyslexia. To obtain such evidence, we compared a group of 100 Dutch-speaking students diagnosed with dyslexia with a control group of 100 students without learning disabilities. Our study showed selective deficits in reading and writing (effect sizes for accuracy between d = 1 and d = 2), arithmetic (d≈1), and phonological processing (d>0.7). Except for spelling, these deficits were larger for speed related measures than for accuracy related measures. Students with dyslexia also performed slightly inferior on the KAIT tests of crystallized intelligence, due to the retrieval of verbal information from long-term memory. No significant differences were observed in the KAIT tests of fluid intelligence. The profile we obtained agrees with a recent meta-analysis of English findings suggesting that it generalizes to all alphabetic languages. Implications for special arrangements for students with dyslexia in higher education are outlined

Knowledge-driven Development of Telescope Control Systems

Since the very first observations of Jupiter's moons by Galileo Galilei more than four centuries ago, the size of ground-based optical telescopes has been growing steadily up to the current generation of telescopes with primary mirrors of 10 meters in diameter. The next generation of "extremely large telescopes" (ELTs) currently under preparation will almost quadruple that figure and will, for the first time, have atmospheric turbulence correction built-in by design. Inevitably, this leads to an increase in complexity and costs of the systems that control the behavior of the telescopes - the telescope control systems. Current practices therefore try to improve the reusability of the control systems design by developing reusable software frameworks, by applying model-based systems engineering, and by integrating off-the-shelf components. These efforts essentially foster the reuse of information within a single engineering discipline, across multiple engineering disciplines, and across different technologies, respectively. Despite the ability of current practices to build even the largest telescopes in history, we identified three fundamental problems that are still present. Firstly, design information (from system-level requirements to detailed software models) is mostly captured in an informal way - even if popular modeling languages are used that promise the opposite - making it impossible for a machine or another person to interpret this information as it was originally intended. Secondly, the graphical representations currently in use add even more informality to this information. Finally, the prevalence of design patterns that were adopted from object-oriented programming restricts the reuse of information now and in the future. We call these problems "fundamental" because they are severely over-constraining the designs, making it very hard to apply solutions in the future, as the telescopes evolve through their projected lifetime of several decades. The goal of this thesis is to work out a solution that addresses those problems, in way that can be realized today. By specifying, implementing, and applying a fundamental methodology change to a real telescope - and not just a temporary test set-up in an "ideal" environment - we can analyze the feasibility and the readiness of such a solution. The fundamental methodology change, promoted by this thesis, aims to shift the current practices from a traditional "model-driven" methodology towards a "knowledge-driven" methodology, in which formal knowledge representation plays a pivotal role. In the framework that we propose, domain knowledge is captured by a set of ontologies: explicit and formal representations of the concepts and other entities in the domains of interest, and the relationships that hold between them. The ontologies that we created formally define the name and the meaning of a whole range of concepts needed to represent telescope control systems, from abstract finite state machines to the specific function blocks of the IEC 61131-3 industrial programming language. A software library called Ontoscript was developed to automatically map those concepts to the primitives of a set of internal domain-specific languages (DSLs) based on CoffeeScript. The telescope control systems can thus be "programmed" by a set of textual DSLs whose semantics are defined by a set of ontologies and by CoffeeScript. Finally, a tool called OntoManager was developed to offer a single interface to the modeling, reasoning, querying, and template-based artifact generation capabilities of the framework in a way that can be used by domain experts who are unfamiliar with formal knowledge representation. OntoManager was used to develop a new control system for the Mercator Telescope, a 1.2 m optical telescope located at the island of La Palma. A total of 9 subsystems were modeled, from the "slow" pneumatic control of the primary mirror support to the much faster, time-critical and safety-critical motion control of the telescope's main axes. For each subsystem, a set of interconnected models represent the systems design (including requirements and systems breakdown), the electric design (from the device level down to the individual wires) and the software design (from the high-level function block declarations down to implementation of the interlock expressions). By reasoning and by querying these models, we were able to automatically generate system specification documents, verification reports and source code for the industrial control system in charge of the telescope and for the top-level control system in charge of the whole observatory. This has lead to the successful installation of the new Mercator telescope control system in June 2016. Evaluation shows that the methodology change proposed by this thesis is feasible, for a real operational telescope of at least the size of the Mercator telescope, even within the constraints imposed by a PhD project. By synthesizing state-of-the-art practices in knowledge engineering, systems engineering, and software engineering we were able to address some fundamental problems of current practices in telescope control system design, thereby making design knowledge more reusable across the boundaries of engineering disciplines and technologies. Analysis of the real-world application with respect to the initial requirements of the framework reveals the added value of the methodology change, but also the limitations and pitfalls of the current implementation. We conclude this thesis by reasoning about the requirements and the possible benefits of generalizing our results to much larger telescopes, or even other application areas.nrpages: 214status: publishe

A practical approach to ontology-enabled control systems for astronomical instrumentation

Even though modern service-oriented and data-oriented architectures promise to deliver loosely coupled control systems, they are inherently brittle as they commonly depend on a priori agreed interfaces and data models. At the same time, the Semantic Web and a whole set of accompanying standards and tools are emerging, advocating ontologies as the basis for knowledge exchange. In this paper we aim to identify a number of key ideas from the myriad of knowledge-based practices that can readily be implemented by control systems today. We demonstrate with a practical example (a three-channel imager for the Mercator Telescope) how ontologies developed in the Web Ontology Language (OWL) can serve as a meta-model for our instrument, covering as many engineering aspects of the project as needed. We show how a concrete system model can be built on top of this meta-model via a set of Domain Specific Languages (DSLs), supporting both formal verification and the generation of software and documentation artifacts. Finally we reason how the available semantics can be exposed at run-time by adding a “semantic layer” that can be browsed, queried, monitored etc. by any OPC UA-enabled client.status: publishe

Design and First Commissioning Results of PLC-based Control Systems at the Mercator Telescope

The 1.2m optical Mercator Telescope (based at the Roque de Los Muchachos Observatory at La Palma) is currently in the commissioning phase of a third permanently installed instrument called MAIA (Mercator Advanced Imager for Asteroseismology), a three-channel frame-transfer imager optimized for rapid photometry. Despite having three cryostats, MAIA is designed as a highly compact and portable instrument by using small Stirling-type cryocoolers, and a single PLC in charge of all temperature control loops, cryocooler interaction, telemetry acquisition and other instrument control related tasks. To accommodate MAIA at the Nasmyth B focal station of the telescope, a new mechanism for the tertiary mirror had to be built since the former mechanism only allowed motor controlled access to the Cassegrain and Nasmyth A focal stations. A second PLC has been installed in order to control the two degrees of freedom of this mirror mechanism by interfacing with its motor controllers, high-precision optical encoders, and limit switches. This PLC is not dedicated to the tertiary mirror control but will serve as a general purpose controller for various tasks related to the telescope and the observatory, as part of a new Telescope Control System primarily based on PLCs and OPC UA communication technology. Due to the central location of the PLC inside the observatory, the position control loops of the mirror mechanism are distributed using EtherCAT as the communication fieldbus. In this paper we present the design and the first commissioning results of both the MAIA instrument control and the tertiary mirror control.status: publishe

Why semantics matter: a demonstration on knowledge-based control system design

Knowledge representation and reasoning are hot topics in academics and industry today, as they are enabling technologies for building more complex and intelligent future systems. At the Mercator Telescope, we've built a software framework based on these technologies to support the design of our control systems. At the heart of the framework is a metamodel: a set of ontologies based on the formal semantics of the Web Ontology Language (OWL), to provide meaningful reusable building blocks. Those building blocks are instantiated in the models of our control systems, via a Domain Specific Language (DSL). The metamodels and models jointly form a knowledge base, i.e. an integrated model that can be viewed from different perspectives, or processed by an inference engine for model verification purposes. In this paper we present a tool called OntoManager, which demonstrates the added value of semantic modeling to the engineering process. By querying the integrated model, our web-based tool is able to generate systems engineering views, verification test reports, graphical software models, PLCopen compliant software code, Python client-side code, and much more, in a user-friendly way.status: publishe

Developing a PLC-friendly state machine model: lessons learned

Modern Programmable Logic Controllers (PLCs) have become an attractive platform for controlling real-time aspects of astronomical telescopes and instruments due to their increased versatility, performance and standardization. Likewise, vendor-neutral middleware technologies such as OPC Unified Architecture (OPC UA) have recently demonstrated that they can greatly facilitate the integration of these industrial platforms into the overall control system. Many practical questions arise, however, when building multi-tiered control systems that consist of PLCs for low level control, and conventional software and platforms for higher level control. How should the PLC software be structured, so that it can rely on well known programming paradigms on the one hand, and be mapped to a well organized OPC UA interface on the other hand? Which programming languages of the IEC 61131-3 standard closely match the problem domains of the abstraction levels within this structure? How can the recent additions to the standard (such as the support for namespaces and object-oriented extensions) facilitate a model based development approach? To what degree can our applications already take advantage of the more advanced parts of the OPC UA standard, such as the high expressiveness of the semantic modeling language that it defines, or the support for events, aggregation of data, automatic discovery, ... ? What are the timing and concurrency problems to be expected for the higher level tiers of the control system due to the cyclic execution of control and communication tasks by the PLCs? We try to answer these questions by demonstrating a semantic state machine model that can readily be implemented using IEC 61131 and OPC UA. One that does not aim to capture all possible states of a system, but rather one that attempts to organize the course-grained structure and behaviour of a system. In this paper we focus on the intricacies of this seemingly simple task, and on the lessons that we've learned during the development process of such a "PLC-friendly" state machine model.status: publishe

Evaluation of OPC UA as the backbone technology for controlling astronomical telescopes

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From knowledge base to control system design: Using semantic modeling and reasoning to design and verify the control systems for the Mercator telescope

Knowledge representation and reasoning are hot topics in academics and industry today, as they are enabling technologies for building more complex and intelligent future systems. At the Mercator Telescope, we’ve built a software framework based on these technologies to support the design of our control systems. At the heart of the framework is a metamodel: a set of ontologies based on the formal semantics of the Web Ontology Language (OWL), to provide meaningful reusable building blocks. Those building blocks are instantiated in the models of our control systems, via a Domain Specific Language (DSL). The metamodels and models jointly form a knowledge base, i.e. an integrated model that can be viewed from different perspectives, or processed by an inference engine for model verification purposes. In this paper we present a tool called OntoManager, which demonstrates the added value of semantic modeling to the engineering process. By querying the integrated model, our web-based tool is able to generate systems engineering views, verification test reports, graphical software models, PLCopen compliant software code, Python client-side code, and much more, in a user-friendly way.Poster presented at the FIIW Research Day 13/11/2015.nrpages: 1status: publishe