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See detailHigh-Level Modular Autopilot Solution for Fast Prototyping of Unmanned Aerial Systems
Rodriguez de Cos, Carlos; Fernandez, Manuel Jesus; Sanchez Cuevas, Pedro Jesus UL et al

in IEEE Access (2020)

A redundant fast prototyping autopilot solution for unmanned aerial systems has been developed and successfully tested outdoors. While its low-level backbone is executed in a Raspberry Pi R 3 + NAVIO2 R ... [more ▼]

A redundant fast prototyping autopilot solution for unmanned aerial systems has been developed and successfully tested outdoors. While its low-level backbone is executed in a Raspberry Pi R 3 + NAVIO2 R with a backup autopilot, the computational power of an Intel R NUC mini-computer is employed to implement complex functionalities directly in Simulink R , thus including in-flight debugging, tuning and monitoring. Altogether, the presented tool provides a flexible and user-friendly high-level environment with enhanced computational capabilities, which drastically reduces the prototyping timespans of complex algorithms -between 50% and 75%, according to our long and proven experience in aerial robotics-, while preventing incidents thanks to its redundant design with a human-in-the-loop pilot on the reliable PX4. Three typical outdoor cases are carried out for validation in real-life scenarios, all mounted in a DJI © F550 platform. Full integration results and telemetry for more than 50 hours of outdoor flight tests are provided. [less ▲]

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See detailTest
Erkihune, Eshetu Nega UL; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2020, December 11)

test

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See detailAsynchronous Stream Data Processing using a Light-Weight and High-Performance Dataflow Engine
Ellampallil Venugopal, Vinu UL; Theobald, Martin UL

Presentation (2020, December 11)

Processing high-throughput data-streams has become a major challenge in areas such as real-time event monitoring, complex dataflow processing, and big data analytics. While there has been tremendous ... [more ▼]

Processing high-throughput data-streams has become a major challenge in areas such as real-time event monitoring, complex dataflow processing, and big data analytics. While there has been tremendous progress in distributed stream processing systems in the past few years, the high-throughput and low-latency (a.k.a. high sustainable-throughput) requirement of modern applications is pushing the limits of traditional data processing infrastructures. This paper introduces a new distributed stream data processing engine (DSPE), called “Asynchronous Iterative Routing” or simply AIR, which implements a light-weight, dynamic sharding protocol. AIR expedites a direct and asynchronous communication among all the worker nodes via multiple Message Passing Interface (MPI) communication channels and thereby completely avoids any additional communication overhead with a dedicated master node. With its unique design, AIR scales out to clusters consisting of up to 8 nodes and 224 cores, performing much better than existing DSPEs, and it performs up to 15 times better than Spark and Flink in terms of sustainable-throughput. [less ▲]

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See detailThe potential of Language Technology and AI
Schommer, Christoph UL

Speeches/Talks (2020)

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See detailCross-Evaluation of Surface Meteorological Data and GNSS-derived Water Vapor with Re-analysis Information for South Georgia Island, South Atlantic Ocean
Erkihune, Eshetu Nega UL; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2020, December 11)

As one of the most important components of the global hydrologic cycle, atmospheric water vapor shows significant variability in both space and time over a large range of scales. This variability results ... [more ▼]

As one of the most important components of the global hydrologic cycle, atmospheric water vapor shows significant variability in both space and time over a large range of scales. This variability results from the interactions of many different factors, including topography and the presence of specific atmospheric processes. One of the key regions for affecting global climatic variations lies in the sub-Antarctic zone over the Southern Ocean with its Antarctic Circumpolar Current and the associated Antarctic Convergence. There, in this cold and maritime region, lies South Georgia Island with its weather and climate being largely affected by both the dominating ocean currents and the strong east ward blowing winds in this zone. While the island forms an important outpost for various surface observations in this largely under-sampled and extremely remote region, it also forms a barrier for these winds due to its high topography, which, in turn, leads to various local meteorological phenomena, such as foehn winds. Surface meteorological data have been available for several stations near King Edward Point (KEP) on South Georgia for much of the 20th century. Since 2013 and 2014, Global Navigation Satellite System (GNSS) data have been available at five locations around the periphery of the island and during a few months in 2016 also radiosonde data have been collected at KEP. This study aims at investigating the consistency between the different surface meteorological data sets such as temperature, pressure and wind direction/speed that have been collected at KEP and a nearby GNSS station on Brown Mountain (BMT) for which we also compare the precipitable water vapor estimates. A cross-evaluation of these data sets with model values from the ERA-Interim re-analyses is carried out to further investigate the performance of both instruments and models. Overall, our preliminary results show high consistency between the surface meteorological observations and the re-analysis model values. It was our main objective to investigate the homogeneity and accuracy of the BMT observation time series through cross-evaluation with the series of the official WMO station at KEP. Air temperature and pressure at both sites from observation and model data are strongly correlated at hourly intervals, reaching correlation coefficients in the range of 0.966 - 0.968 for the former data set. The difference temperature time series shows seasonal variations but no obvious steps. The difference pressure time series is flat, also indicating no discontinuities. A cross-evaluation of the wind observations shows the distinct directional feature at KEP for a station in a valley where the winds are funneled through the valley. For BMT the wind observations confirm the main directions of winds but also show the openness of the station from all directions. The observations of temperature, pressure, humidity and GNSS-derived PWV clearly show the signatures of the frequent foehn events. [less ▲]

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See detailUnderstanding through Experimentation: An Experimental Media Archaeological Approach to Early Twentieth-Century Home Movie Making
van der Heijden, Tim UL

Scientific Conference (2020, December 11)

This presentation addresses the question in what ways visual media have contributed to the construction of a specific view on twentieth-century century (family) life by means of an experimental media ... [more ▼]

This presentation addresses the question in what ways visual media have contributed to the construction of a specific view on twentieth-century century (family) life by means of an experimental media archaeological approach to early home movie making. Based on hands-on experiments with an original Ciné-Kodak 16mm film camera from 1930, it will be shown how filming one’s family was never truly a neutral practice of capturing everyday life. Rather, making a home movie should be regarded a highly “co-constructive” practice that includes various social, sensorial, technological and user-related dimensions. The presentation reflects work in progress from the research project “Doing Experimental Media Archaeology” (DEMA) of the Centre for Contemporary and Digital History (C2DH) of the University of Luxembourg: https://dema.uni.lu/. [less ▲]

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See detailTransition from in-class to outdoor learning with real-world mathematical modelling: PhD research project 2015-2021
Haas, Ben; Lavicza, Zsolt; Dana-Picard, Thierry (Noah) et al

Presentation (2020, December 10)

In this PhD outline, I will present highlights from my PhD research project on mathematical modelling with real-world information in the classroom, remote teaching and outdoor learning in Luxemburg ... [more ▼]

In this PhD outline, I will present highlights from my PhD research project on mathematical modelling with real-world information in the classroom, remote teaching and outdoor learning in Luxemburg. Through design-based explanatory studies, I investigated different technology enhanced tasks, learning and teaching settings that could likely engage students in understanding and transferring mathematical modelling to their living environments. The selected design-based research methodology and its characteristics, allowed to adapt task designs, settings and methods during my PhD research project. Hence, firstly, I investigated process skills learning (e.g.: mathematical modelling) with an automated tutoring system (the educational technology software MathemaTIC) within an international project. Although findings were promising, I redesigned my interventions to connect further students mathematical modelling learning to real-world information. Thus, secondly, I performed mathematical modelling tasks with augmented reality on real-world objects in remote teaching and in special needs educations. Utilising findings of these studies and a redesign of the intervention based on outdoor mathematical trails, thirdly, I undertook my final study. In pre-service teacher higher education, I explored outdoor mathematical modelling with an integrated STEAM (Science, technology, engineering, arts, and mathematics) approach. With the aim of such holistic approach, I collected data on education-related perceptions from different stakeholders of elementary school education (students, parents, in-service, and pre service teachers) and developed conceptual frameworks on task creation, mathematical modelling, and stakeholders' roles. In my PhD research project, I aspired to contribute and explain how in-class learning and teaching could be connected and transferred to mathematical modelling within students living environments. Although there are many crucial moments, method choices and findings within these studies, in this report, I will offer highlights of my PhD work and results. [less ▲]

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See detailGood practice between good neighboors
Molostoff, Leslie UL; Tischer, Peter

Presentation (2020, December 10)

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See detailBREXIT: état des lieux
Danescu, Elena UL; Esposito, Marie-Claude; Da Silva, Joana

Speeches/Talks (2020)

Au 31 janvier 2020 à minuit (heure de Bruxelles), le Royaume-Uni a quitté l'Union européenne. Cette sortie n'est pourtant pas totale : conformément à l’accord de retrait, le pays est entré dans une ... [more ▼]

Au 31 janvier 2020 à minuit (heure de Bruxelles), le Royaume-Uni a quitté l'Union européenne. Cette sortie n'est pourtant pas totale : conformément à l’accord de retrait, le pays est entré dans une transition qui lui permet de négocier sa future relation avec l’UE, tout en restant provisoirement intégré à un certain nombre de politiques européennes. Cette phase doit prendre fin au 31 décembre 2020 au plus tôt, mais les pourparlers semblent actuellement en impasse. S’il demeure la conséquence directe du référendum organisé le 23 juin 2016 par l’ancien Premier Ministre David Cameron, le « Brexit » reflète de longues décennies de rapports tumultueux avec l’Europe supranationale, qui ont nourri l’euroscepticisme et anti-européenisme des Britanniques.[...] [less ▲]

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See detailDEMAND-SIDE-MANAGEMENT MIT WÄRMEPUMPEN IN LUXEMBURG - POTENZIALE UND HERAUSFORDERUNGEN DER WÄRMEPUMPENFLEXIBILITÄT FÜR DIE SYSTEMINTEGRATION DER ERNEUERBAREN ENERGIEN
Bechtel, Steffen UL

Doctoral thesis (2020)

In 2020 the European Union introduced the “Green Deal” and declared the target of climate neutrality until 2050. The necessary measures will lead to a massive roll-out of fluctuating renewable energies ... [more ▼]

In 2020 the European Union introduced the “Green Deal” and declared the target of climate neutrality until 2050. The necessary measures will lead to a massive roll-out of fluctuating renewable energies such as wind power and photovoltaic. This in turn will lead to an increasing need for flexibility in the energy system. The design of the future European internal market for electricity intends to let end-consumers actively participate by managing their consumption based on variable electricity prices and in that way contributing to the flexibility demand. For private households, these Demand-Side-Management measures target heat pumps in particular. This work analyzes the flexibility potential of heat pumps in residential buildings and addresses challenges in the Luxembourgish context. The time horizon for the evaluation is defined as 2030. The methodology presented in this work is applicable to similar regions in Europe. The research questions are investigated by the means of thermal simulation. The software TRNSYS is used for the building models and heating systems. A Model-Predictive-Control, developed in MATLAB, is sending control signals to the heat pump that are based on variable electricity tariffs. The heat extraction of the thermal energy storage tank is determined by a neural network, so that the Model-Predictive-Control in itself works without an integrated building model. The suitability of the approach is validated by the simulation results. Based on the national developments in the building stock, there is a theoretical heat pump potential of 236-353 MWel that can offer flexibility. The band with arises because of different suppositions for the yearly refurbishment rate. The technical potential is significantly lower and is determined by the developments of the national heat pump market. As the data availability for Luxemburg was insufficient, a heat market study was initiated that investigated sales numbers for the period of 2014-2018 and derived scenarios until 2030. The technical potential in conclusion amounts to 30-73 MWel. The insights of the national context are used for the design of the simulation models. The concept of Demand-Side-Management is tested with numerous simulation cases and is then evaluated on aspects of energy efficiency, profitability and load shifting. In total there are three reference buildings, one single-family and one multi-family house, each according to the energetic standard of a new construction, and one single-family house that meets the legal requirements for energetic refurbishment in Luxembourg. In order to demonstrate the influence of the heat source there are simulations with air-to-water as well as geothermal heat pumps. The analysis furthermore considers six different thermal energy storage capacities. The influence of the predictive control strategy is demonstrated by a comparison with reference cases that work with a common control. The flexible electricity tariffs are based on real market data of the EPEX-Spot Day-Ahead auction and is completed with grid fees and taxes in Luxembourg. The simulation results confirm the suitability of the Model-Predictive-Control approach without integrated building model. Air-to-water heat pumps achieve better efficiency and cost reduction than geothermal heat pumps, as they have two ways to reduce the costs: via the variable electricity tariffs and via a performance optimization of the heat pump itself. The performance optimization is the preferred choice of the control strategy if the price profile consists of mainly static components. Buildings with high insulation level show a sharper reaction to price signals than buildings with lower insulation standard. For the latter in return the absolute cost reduction potential is better as the overall energy demand is higher. With low capacity thermal energy storage, the energy efficiency and cost reduction potential are limited since the reaction to price signals immediately leads to a temperature rise in the tank counteracting the overall objective by increasing the heat pump consumption. With increasing tank capacity, this aspect improves. Nevertheless, there is a limit where the increasing heat losses of the tank compensate the positive aspects of bigger tanks. As the heating systems are usually not equipped with larger thermal energy storage tanks, there is an extra investment for the end-consumer that needs to be compensated by the cost reduction of the Demand-Side-Management. This profitability is only given for the multi-family house and the less insulated single-family house, equipped with an air-to-water heat pump and small to medium sized storage tanks. Two alternative price profiles are tested in order to demonstrate the influence of the price signals. In the first case, a higher volatility of the prices is presumed, to reflect a higher market share of renewable energies. In the second case variable grid fees are added to the volatile prices to further increase the incentive of Demand-Side-Management. In all simulation cases the cost reduction increases so that that buildings with high thermal insulation and air-to-water heat pump are profitable with medium sized thermal energy storage. At the same time a change of behavior of the predictive controller can be observed as the price signals become more attractive than the aspect of performance optimization, leading to an increased electricity consumption in comparison to the previous price profile. An overall economic potential of 22-53 MWel can be concluded. The numerous constraints for the heat pump operation lead to an implicit load management effect that is difficult to interpret. Nevertheless, there is a clear systemic benefit of Demand-Side-Management that result from the better performance of air-to-water heat pumps and the highly probable reaction to extreme price signals. The assessment of a high number of heat pumps by the grid operator in order to stabilize the electricity grid is questionable. The main counter arguments are the limited reliability considering the constraints and the low electric power compared to the e-mobility that will be the major challenge of the low voltage grids in the nearer future. Concepts, where energy providers or direct marketers assess the flexibility to optimize procurement strategies seems more interesting. In this context the profitability is the main question that cannot be verified based on the findings, except if there is added value stemming from synergy effects that were not considered in this work. In relation to the peak demand of the Luxembourgish energy system there is a relevant heat pump potential for Demand-Side-Management. In the nearer future the subject should be further investigated, keeping in mind the findings and sensitivities presented in this work. [less ▲]

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See detailRecycling of gravel wash mud for manufacturing CO2-reduced cement
Thapa, Vishojit Bahadur UL

Doctoral thesis (2020)

The present research project “CO2REDCEM” is carried out at the Laboratory of Solid Structures (LSS) of the University of Luxembourg, in close collaboration with Luxembourgish industrial partners (Cimalux ... [more ▼]

The present research project “CO2REDCEM” is carried out at the Laboratory of Solid Structures (LSS) of the University of Luxembourg, in close collaboration with Luxembourgish industrial partners (Cimalux S.A., Carrières Feidt S.A. and Contern S.A.). This project aims at reducing the generation of CO2 emissions during cement production by minimisation of the use of cement clinker or its complete replacement by new binder compositions and concepts, containing novel material resources derived from local unused industrial waste products. Such a potential raw material is gravel wash mud (GWM), which occurs as a waste product from gravel mining. This clayey mud is collected from a sludge reservoir, located in the North West of Luxembourg. Currently, this waste product is landfilled without any further use. However, this prime material offers very promising properties, which require a thorough characterisation and verification before its revalorisation as a viable supplementary cementitious material (SCMs). Reusing or recycling of waste elements into goods has been among the greatest ambitions of our and earlier generations, and it will take a more important role in the future economy. One primary goal of this project is to replace the “end-of-life” concept of gravel wash mud by reusing it as new raw material. This endeavour will bring double benefit to environment as the waste is prevented from landfilling, and it is revalorised as a prime resource in another system.This research work shares the outcomes from the assessment of the performance of the prime material GWM within the following binder concepts and binder reaction mechanisms: • The use of gravel wash mud (GWM) powders as a precursor material for the synthesis of alkali-activated binders: A “cementless” binder is synthesised by alkaline activation of processed and calcined GWM powders. The mitigation of the CO2 emissions is achieved by the calcination process of the clayey gravel wash mud, which requires less thermal energy and thus lower energy consumption than for cement clinker production. • Substitution of Ordinary Portland Cement (OPC) by calcined GWM powders: Cement and concrete mixtures are prepared based on partial replacement of Portland cement by calcined GWM powders. This study presents the investigations on the involved reaction mechanisms (pozzolanic and cementitious hydration reactions), the optimal mixture configurations and the optimal material treatment processes. • The development of lime-Metakaolin-GWM binder concepts: Mixtures without cement are developed using GWM and other constituents, classified as industrial by-products. This research includes the mineralogical and microstructural characterisation of the constituents, the understanding of the reaction mechanism, and the optimisation of the mixtures to enhance the performance of the novel cementitious products. This thesis allowed to assess the performance of the waste product GWM as a valid pozzolanic prime material and to understand the requirements on physical, chemical and mineralogical characteristics of any potential raw material to ensure its permissibility as an alternative supplementary cementitious material (SCM). [less ▲]

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See detailUne télé-justice est-il encore une justice?
Becker, Katrin UL

Diverse speeches and writings (2020)

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See detailA NEW CORRESPONDENCE BETWEEN TASEPAND BURGERS’ EQUATION
Flandoli, Franco; Gess, Benjamin; Grotto, Francesco UL

E-print/Working paper (2020)

We introduce a new particle model, which we dub Active Bi-Directional Flow, conjugated to the Totally Asymmetric Exclusion Processin discrete time. We then associate to our model intrinsically stochastic ... [more ▼]

We introduce a new particle model, which we dub Active Bi-Directional Flow, conjugated to the Totally Asymmetric Exclusion Processin discrete time. We then associate to our model intrinsically stochastic, non-entropic weak solutions of Burgers’ equation onR, thus linking the latter tothe KPZ universality class. [less ▲]

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Peer Reviewed
See detailExtended Producer Responsibility in the Construction Sector through Blockchain, BIM and Smart Contract Technologies
Akbarieh, Arghavan UL; Carbone, William; Schäfer, Markus UL et al

Poster (2020, December 09)

Despite the enormous amount of raw or secondary materials flowing within the construction industry, the actual available volume of materials and their respective End-of-Lifecycle (EoL) treatment is not ... [more ▼]

Despite the enormous amount of raw or secondary materials flowing within the construction industry, the actual available volume of materials and their respective End-of-Lifecycle (EoL) treatment is not regulated nor uniform. On top of that, the EoL responsibility of different stakeholders after the future building deconstruction is confusing and disputable. Consequently, different sustainability policies and metrics suffer from inaccurately reported volumes of circulating materials in the economy. Hence, this article aims to find a new way to improve and regulate the EoL treatment of recyclable materials and to create value for them. The ultimate goal of the proposed framework is to make original manufacturers responsible for the EoL treatment of their recyclable construction materials and products under the Extended Producers Responsibility (EPR) policy that is enacted in the European Union for sustainable management of waste streams. Adhering to the EPR is difficult for buildings as they are long-term and complex assets. A high degree of transparency, accuracy and security is required to correctly track the lifecycle information of building parts and their respective manufacturers for the EPR implementation. For this purpose, a framework is conceptualised based on the immutability and transparency of blockchain technology to remove trust and trace barriers in the current supply chain. The proposed conceptual model results from the synergy of Building Information Modelling (BIM) technology, material and component banks, blockchain technology and smart contracts for the EoL treatment of recyclable materials. As a result, a data-driven and closed-loop material cycle will be accomplished. This paper demonstrates that through self-executing smart contracts, a clear line of responsibility and ownership could be defined while manufacturers could be made accountable in the post-consumer phase of their construction products. [less ▲]

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Peer Reviewed
See detailFormation of ultra-thin Ge1−xSnx/Ge1−x−ySixSny quantum heterostructures and their electrical properties for realizing resonant tunneling diode
Suwito, Galih Ramadana; Fukuda, Masahiro; Suprayoga, Edi et al

in Applied Physics Letters (2020), 117(23), 232104

Huge thermal noise owing to the narrow energy bandgap is one of the critical issues for group IV-based photonics in the mid-infrared regime. With this motivation, we examined to form Ge1−xSnx ... [more ▼]

Huge thermal noise owing to the narrow energy bandgap is one of the critical issues for group IV-based photonics in the mid-infrared regime. With this motivation, we examined to form Ge1−xSnx/Ge1−x−ySixSny quantum heterostructures (QHs) by molecular beam epitaxy for realizing resonant tunneling diodes composed of group-IV materials. We confirmed the formation of approximately 2 nm-thick Ge1−xSnx/Ge1−x−ySixSny QHs with atomically flat interfaces by x-ray diffraction and transmission electron microscopy methods. Moreover, by the current density–voltage (J–V) measurement at 10 K, we observed the occurrence of a non-linear distinct hump in the J–V characteristic, which is possibly originated from quantum transport of heavy holes. According to the tunneling transmission spectra simulation result, the hump property would be due to two possible scenarios: a resonant tunneling of heavy holes in the QH and/or a resonance phenomenon that heavy holes pass just above a potential barrier. [less ▲]

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See detailWie haben sich emotionale Anforderungen für Arbeitnehmer in Luxemburg über die Zeit entwickelt?
Sischka, Philipp UL; Steffgen, Georges UL

E-print/Working paper (2020)

Im Rahmen dieser Newsletter wird analysiert, wie sich emotionale Anforderungen für Arbeitnehmer in Luxemburg über die letzten Jahre entwickelt haben. Emotionale Anforderungen sind mit reduziertem Well ... [more ▼]

Im Rahmen dieser Newsletter wird analysiert, wie sich emotionale Anforderungen für Arbeitnehmer in Luxemburg über die letzten Jahre entwickelt haben. Emotionale Anforderungen sind mit reduziertem Well-Being assoziiert. Dabei weisen Arbeitnehmer mit ausgeprägten emotionalen Anforderungen insbesondere ein höheres Burnoutlevel auf. Zwischen 2016 und 2020 kam es zu einem deutlichen Anstieg der emotionalen Anforderungen. Arbeitnehmerinnen weisen über die Zeit konstant höhere emotionale Anforderungen auf im Vergleich zu Arbeitnehmern. Insbesondere Arbeitnehmer in akademischen Berufen, Manager und Arbeitnehmer in Dienstleistungsberufen weisen über die Zeit konstant hohe emotionale Anforderungen auf. Bediener von Anlagen und Hilfsarbeitskräfte weisen dagegen einen Anstieg zwischen 2016 und 2020 auf. [less ▲]

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See detailBoosting Automated Program Repair for Adoption By Practitioners
Koyuncu, Anil UL

Doctoral thesis (2020)

Automated program repair (APR) attracts a huge interest from research and industry as the ultimate target in automation of software maintenance. Towards realizing this automation promise, the research ... [more ▼]

Automated program repair (APR) attracts a huge interest from research and industry as the ultimate target in automation of software maintenance. Towards realizing this automation promise, the research community has explored various ideas and techniques, which are increasingly demonstrating that APR is no longer fictional. Although literature techniques constantly set new records in fixing a significant fraction of defects within well-established benchmarks, we are not aware of large-scale adoption of APR in practice. Meanwhile, open-source and commercial organizations have started to reflect on the potential of integrating some automated steps in the software development cycle. Actually, the current practice has several development settings that use a number of tools to automate and systematize various tasks such as code style checking, bug detection, and systematic patching. Our work is motivated by this fact. We advocate that systematic and empirical exploration of the current practice that leverage tools to automate debugging tasks would provide valuable insights for rethinking and boosting the APR agenda towards its acceptability by developer communities. We have identified three investigation axes in this dissertation. First, mining software repositories towards understanding code change properties that could be valuable to guide program repair. Second, analyzing communication channels in software development in order to assess to what extent they could be relevant in a real-world program repair scenario. Third, exploring generic concepts of patching in the literature for establishing a common foundation for program repair pipelines that can be integrated with industrial settings. This dissertation makes the following contributions to the community: • An empirical study of tool support in a real development setting providing concrete insights on the acceptance, stability and the nature of bugs being fixed by manually-craft patches vs tool-supported patches and manifests opportunities for improving automated repair techniques. • A novel information retrieval based bug localization approach that learns how to compute the similarity scores of various types of features. • An automated mining strategy to infer fix pattern that can be integrated to automated program repair pipelines. • A practical bug report driven program repair pipeline. [less ▲]

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See detailRobust Real-time Sense-and-Avoid Solutions for Remotely Piloted Quadrotor UAVs in Complex Environments
Wang, Min UL

Doctoral thesis (2020)

UAV teleoperation is a demanding task: to successfully accomplish the mission without collision requires skills and experience. In real-life environments, current commercial UAVs are to a large extent ... [more ▼]

UAV teleoperation is a demanding task: to successfully accomplish the mission without collision requires skills and experience. In real-life environments, current commercial UAVs are to a large extent remotely piloted by amateur human pilots. Due to lack of teleoperation experience or skills, they often drive UAVs into collision. Therefore, in order to ensure safety of the UAV as well as its surroundings, it is necessary for the UAV to boast the capability of detecting emergency situation and acting on its own when facing imminent threat. However, the majority of UAVs currently available in the market are not equipped with such capability. To fill in the gap, in this work we present 2D LIDAR based Sense-and-Avoid solutions which are able to actively assist unskilled human operator in obstacle avoidance, so that the operator can focus on high-level decisions and global objectives in UAV applications such as search and rescue, farming etc. Specifically, with our novel 2D LIDAR based obstacle detection and tracking algorithm, perception-assistive flight control design, progressive emergency evaluation policies and optimization based and adaptive virtual cushion force field (AVCFF) based avoidance strategies, our proposed UAV teleoperation assistance systems are capable of obstacle detection and tracking, as well as automatic obstacle avoidance in complex environment where both static and dynamic objects are present. Additionally, while the optimization based solution is validated in Matlab, the AVCFF based avoidance system has been fully integrated with sensing system, perception-assistive flight controller on the basis of the Hector Quadrotor open source framework, and the effectiveness of the complete Sense-and-Avoid solution has been demonstrated and validated on a realistic simulated UAV platform in Gazebo simulations, where the UAV is operated at a high speed. [less ▲]

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