Accuracy in Diagnosis of Celiac Disease Without Biopsies in Clinical Practice

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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

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

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

Suitability assessment of OPC UA as the backbone of ground-based observatory control systems

A common requirement of modern observatory control systems is to allow interaction between various heterogeneous subsystems in a transparent way. However, the integration of off-the-shelf (OTS) industrial products - such as Programmable Logic Controllers (PLCs) and Supervisory Control And Data Acquisition (SCADA) software - has long been hampered by the lack of an adequate interfacing method. With the advent of the Unified Architecture (UA) version of OPC (Object Linking and Embedding for Process Control), the limitations of the original industry-accepted interface are now lifted, and also much more functionality has been defined. In this paper the most important features of OPC UA are matched against the requirements of ground-based observatory control systems in general and in particular of the 1.2m Mercator Telescope. We investigate the opportunities of the “information modelling” idea behind OPC UA, which could allow an extensive standardization in the field of astronomical instrumentation, similar to the efforts emerging in several industry domains. Because OPC UA is designed for both horizontal and vertical integration of heterogeneous subsystems, we explore its capabilities to serve as the backbone of a dependable and scalable observatory control system, treating industrial components like PLCs no differently than custom software components. Performance measurements and tests with a sample of OTS OPC UA products are presented.status: publishe

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

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A novel double-blind, placebo-controlled food challenge matrix for milk and raw egg

Background: The double-blind, placebo-controlled food challenge (DBPCFC) is still considered to be the gold standard in food allergy diagnosis. This test is however not common practice in routine due to several practical limitations, especially for non-IgE-mediated food allergy with its typical delayed food allergic reactions. Objective: The aim of this study was to develop and evaluate DBPCFC matrices for the diagnosis of milk and egg allergies which can be applied at home for the diagnosis of delayed food allergic reactions. The main focus was the blinding of milk and raw egg and the development of matrices which can be prepared and consumed conveniently at home with a sufficiently long shelf life (+/-6 months or longer). Methods: A sensory test evaluated the blinding of the egg and milk in the matrices. The microbiological analysis confirmed the safety and stability of the developed matrices. To assess the applicability of the matrices, a pilot DBPCFC study for milk including 7 patients was conducted. Results: Sensory tests confirmed that the masking of the allergenic ingredients was sufficient. Microbial safety and stability of the matrices were confirmed up to 6 months of storage at ambient temperatures in the dark. The DBPCFC for milk showed different outcomes and proved its applicability for use at home. Conclusion: A novel stable DBPCFC matrix for milk and raw egg has been developed that allows convenient use at the patients' home. (C) 2019 S. Karger AG, Base