Unique identification of elements in evolving models : towards fine-grained traceability in model-driven engineering

Model-driven engineering (MDE) is a widely accepted methodology in software engineering. At the same time, the ability to retrace the engineering process is an important success factor for software projects. In MDE, however, such traceability is often impeded by the inadequate management of model evolution. Although models have a very fine-grained structure, their different revisions and variants are prevalently managed as monoliths in a file-based software configuration management (SCM). This causes the identification problem: if the fine-grained elements are not assigned with globally unique identifiers, we cannot identify them over time. If such identifiers would be given, they can be misleading. As a consequence, we cannot comprehend the evolution of elements and traceability relationships among the elements cannot be managed sufficiently. This thesis presents a novel solution to the identification problem. It establishes a representation to describe the history of a model and its fine-grained elements inside. The key feature of the representation is a new kind of traceability relationship, called identification links. They allow us to identify elements of a given revision in other revisions or variants of the model. The identification is even applicable to anonymous elements and model fragments. It provides us with a broad spectrum of opportunities: e.g. management of fine-grained traceability links, evolution analysis, merging of development branches. Due to the expression of model evolution in the history representation, we are further able to capture the changes that have been applied to the traced elements. This thesis further presents an algorithm to infer the identification links automatically. The approach does not rely on persistent identifiers, but it utilizes a similarity-based model comparison technique to locate the model elements in other revisions. The algorithm and the history representation have been implemented in a prototype. It is metamodel and tool independent and can work with an arbitrary SCM. Existing modeling environments do not have to be modified. Traceability information and evolution information is accessible through a service interface and can thus be integrated in arbitrary tools. The evaluation of our approach by means of controlled experiments with data from real models attested excellent precision and recall values for the identification of model elements over time. Furthermore, different evolution analysis tools have already been built on our approach, which documents the practical applicability of our solution.Die modellgetriebene Entwicklung ist eine weit verbreitete Methode zur Softwareentwicklung. Die ungeeignete Versionierung von Modellen verhindert jedoch oftmals die Nachverfolgbarkeit des Entwicklungsprozesses. Trotz ihrer feinkörnigen Struktur werden Modelle oft monolithisch auf Basis dateibasierter Konfigurationsmanagementsysteme verwaltet. Modellelemente können in diesem Fall nicht über die Zeit hinweg identifiziert werden, weil globale Identifizierer entweder fehlen oder irreführend sein können. Aufgrund dieses Identifikationsproblems können Änderungen an Modellelementen nur sehr schwer nachvollzogen werden. Außerdem können Referenzen zur Nachverfolgbarkeit zwischen Elementen verschiedener Revisionen nicht sinnvoll verwaltet werden. Diese Dissertation löst das Identifikationsproblem. Sie führt eine Repräsentation ein, mit der die Historie von Modellen und deren feinkörnigen Elementen abgebildet werden kann. Ein zentraler Bestandteil dieser Repräsentation sind Identifizierungslinks, die es ermöglichen ein gegebenes Element in anderen Revisionen oder Varianten des Modells wiederzufinden. Der Ansatz unterstützt auch anonyme Elemente und komplette Modellfragmente. Diese neuartige Identifizierung ermöglicht z.B. die Verwaltung von feinkörniger Nachverfolgbarkeitsinformation, die Analyse von Modellevolution oder das Mischen von Entwicklungszweigen. Da die Repräsentation auch die Evolution eines Modells abbilden kann, können die Veränderungen identifizierter Elemente besser erfasst werden. Zudem wird in dieser Dissertation ein Algorithmus entwickelt, mit dem Identifizierungslinks zwischen Modellelementen verschiedener Revisionen inferiert werden. Dieser stützt sich nicht auf persistente Identifizierer, sondern nutzt einen ähnlichkeitsbasierten Differenzalgorithmus, um Elemente in anderen Revisionen wiederzufinden. Der Algorithmus und die Historienrepräsentation wurden in einem modelltyp- und werkzeugunabhängigen Prototyp implementiert, der mit beliebigen Konfigurationsmanagementsystemen zusammenarbeitet, ohne dass diese angepasst werden müssen. Die Informationen zur Nachverfolgbarkeit und Evolution von Modellelementen sind über eine Programmierschnittstelle abfragbar, die sich in beliebigen Werkzeugen nutzen lässt. Der beschriebene Ansatz wurde mit kontrollierten Experimenten auf Basis realer Modellhistorien erfolgreich evaluiert. Darüber hinaus wurde seine praktische Anwendbarkeit durch verschiedene darauf aufbauende Werkzeuge zur Evolutionsanalyse belegt

Amplifications of picosecond laser pulses in tapered semiconductor amplifiers: Numerical simulations versus experiments

We apply a travelling wave model to the simulation of the amplification of laser pulses generated by Q-switched or mode-locked distributed-Bragg reflector lasers. The power amplifier monolithically integrates a ridge-waveguide section acting as pre-amplifier and a flared gain-region amplifier. The diffraction limited and spectral-narrow band pulses injected in to the pre-amplifier have durations between 10 ps and 100 ps and a peak power of typical 1 W. After the amplifier, the pulses reach a peak power of several tens of Watts preserving the spatial, spectral and temporal properties of the input pulse. We report results obtained by a numerical solution of the travelling-wave equations and compare them with experimental investigations. The peak powers obtained experimentally are in good agreement with the theoretical predictions. The performance of the power amplifier is evaluated by considering the dependence of the pulse energy as a function of different device and material parameters

Use of rrocess mining to verify and validate simulation models in production and logistics

Verification and validation (V&V) are imperative to ensure the success of a simulation study but are often insufficiently considered in practice due to the effort associated with V&V-activities. This contribution discusses the application of process mining techniques to check the validity of discrete event simulation models in production and logistics. For this purpose, we present a morphological box which highlights the scope of process mining in the context of V&V for simulation models and distinguishes between different V&V items, aspects of validity, and V&Vcriteria. Subsequently, the paper describes how a real system can be related to the behaviour of a simulation model and presents two scenarios for process miningsupported V&V using a reference example

Are there clinically relevant anatomical differences of the proximal femur in patients with mild dysplastic and primary hip osteoarthritis? A CT-based matched-pairs cohort study

AIM: To investigate the three-dimensional anatomy and shape of the proximal femur, comparing patients with secondary osteoarthritis (OA) due to mild developmental dysplasia of the hip (DDH) and primary hip OA. MATERIALS AND METHODS: This retrospective radiographic computed tomography (CT)-based study investigated proximal femoral anatomy in a consecutive series of 84 patients with secondary hip OA due to mild DDH (Crowe type I&amp;II/Hartofilakidis A) compared to 84 patients with primary hip OA, matched for gender, age at surgery, and body mass index. RESULTS: Men with DDH showed higher neck shaft angles (127±5° vs. 123±4°; p&lt;0.001), whereas women with DDH had a larger femoral head diameter (46±4 vs. 44±3 mm; p=0.002), smaller femoral offset (36±5 vs. 40±4 mm; p&lt;0.001), decreased leg torsion (25±13° vs. 31±16°; p=0.037), and a higher neck shaft angle (128±7° vs. 123±4°; p&lt;0.001) compared to primary OA patients. Similar patterns of the three-dimensional endosteal canal shape of the proximal femur, but a high inter-individual variability for femoral canal torsion at the meta-diaphyseal level were found for DDH and primary OA patients. CONCLUSION: Standard cementless stem designs are suitable to treat patients with secondary hip OA due to mild DDH; however, high patient variability and subtle anatomical differences in the proximal femur should be respected.</p

Index-antiguiding in narrow-ridge GaN-based laser diodes investigated by measurements of the current-dependent gain and index spectra and by self-consistent simulation

The threshold current density of narrow (1.5 {\mu}m) ridge-waveguide InGaN multi-quantum-well laser diodes, as well as the shape of their lateral far-field patterns, strongly depend on the etch depth of the ridge waveguide. Both effects can be attributed to strong index-antiguiding. A value of the antiguiding factor R = 10 is experimentally determined near threshold by measurements of the current-dependent gain and refractive index spectra. The device performances are simulated self-consistently solving the Schr\"odinger-Poisson equations and the equations for charge transport and waveguiding. Assuming a carrier-induced index change which matches the experimentally determined antiguiding factor, both the measured high threshold current and the shape of the far-field pattern of lasers with shallow ridges can be reproduced theoretically.Comment: This is an author-created, un-copyedited version of an article accepted for publication in the IEEE Journal of Quantum Electronics. IEEE is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

Manufacturing and logistics use cases on Ccombining discrete event simulation and process mining

This paper provides an overview on two approaches to combine processmining and discrete-event simulation in manufacturing and logistics for mutual benefit. One approach focuses on generating simulation models based on process models, while the other approach utilizes process models to validate existing simulation models. Both approaches are explained on a conceptual and technical level. In addition, two real-world use cases from the field of intralogistics and from battery cell assembly are presented. Initial experiences and lessons learned from applying the approaches to the use cases are discussed. The findings illustrate the potential and the limitations of the explored combinations

The Berlin Brain-Computer Interface: Progress Beyond Communication and Control

The combined effect of fundamental results about neurocognitive processes and advancements in decoding mental states from ongoing brain signals has brought forth a whole range of potential neurotechnological applications. In this article, we review our developments in this area and put them into perspective. These examples cover a wide range of maturity levels with respect to their applicability. While we assume we are still a long way away from integrating Brain-Computer Interface (BCI) technology in general interaction with computers, or from implementing neurotechnological measures in safety-critical workplaces, results have already now been obtained involving a BCI as research tool. In this article, we discuss the reasons why, in some of the prospective application domains, considerable effort is still required to make the systems ready to deal with the full complexity of the real world.EC/FP7/611570/EU/Symbiotic Mind Computer Interaction for Information Seeking/MindSeeEC/FP7/625991/EU/Hyperscanning 2.0 Analyses of Multimodal Neuroimaging Data: Concept, Methods and Applications/HYPERSCANNING 2.0DFG, 103586207, GRK 1589: Verarbeitung sensorischer Informationen in neuronalen Systeme

Incidence of central retinal artery occlusion peaks in winter season

IntroductionStroke incidence exhibits seasonal trends, with the highest occurrences observed during winter. This study investigates the incidence of central retinal artery occlusion (CRAO), a stroke equivalent of the retina, and explores its monthly and seasonal variations, as well as potential associations with weather and ambient air pollutants.MethodsA retrospective search of medical records spanning 15 years (January 2008–December 2022) was conducted at the University Eye Hospital Tübingen, Germany, focusing on diagnosed cases of CRAO. Incidences were evaluated on a monthly and seasonal basis (winter, spring, summer, fall). Weather data (temperature, precipitation, atmospheric pressure) and concentrations of ambient air pollutants [fine particulate matter (PM2.5), coarse particulate matter (PM10), nitrogen dioxide (NO2), and ozone (O3)], were analyzed for a potential association with CRAO incidence.ResultsOut of 432 patients diagnosed with CRAO between 2008 and 2022, significantly varying incidences were observed monthly (p = 0.025) and seasonally (p = 0.008). The highest rates were recorded in February and winter, with the lowest rates in June and summer. Concentrations of NO2, PM2.5 and lower ambient air temperature (average, minimum, maximum) showed significant correlations with CRAO incidence.DiscussionThis comprehensive 15-year analysis reveals a pronounced winter peak in CRAO incidence, with the lowest occurrences in summer. Potential associations between CRAO incidence and ambient air pollutants and temperature underscore the importance of considering seasonal trends and call for further investigations to elucidate contributing factors, potentially leading to targeted preventive strategies and public health interventions

High data rate modulation of high power 1060-nm DBR tapered lasers with separate contacts

Direct optical modulation at 2.5 Gb/s with amplitude of more than 0.5 W has been demonstrated in single longitudinal mode distributed Bragg reflector tapered lasers emitting at 1060 nm with separated injection of the ridge waveguide and tapered sections. The modulating signal of ~110 mA peak to peak was applied to the ridge waveguide section, yielding a high modulation efficiency of ~5 W/A. The large-signal frequency response of the experimental set-up was limited by the bandwidth of the electrical amplifier rather than by the internal dynamics of the laser, indicating that higher bit rates could be achieved with improved driving electronics