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See detailCloud Providers Viability: How to Address it from an IT and Legal Perspective?
Bartolini, Cesare UL; El Kateb, Donia UL; Le Traon, Yves UL et al

in Altmann, Jörn; Silaghi, Gheorghe Cosmin; Rana, Omer F. (Eds.) Economics of Grids, Clouds, Systems, and Services (2016)

A major part of the commercial Internet is moving towards a cloud paradigm. This phenomenon has a drastic impact on the organizational structures of enterprises and introduces new challenges that must be ... [more ▼]

A major part of the commercial Internet is moving towards a cloud paradigm. This phenomenon has a drastic impact on the organizational structures of enterprises and introduces new challenges that must be properly addressed to avoid major setbacks. One such challenge is that of cloud provider viability, that is, the reasonable certainty that the Cloud Service Provider (CSP) will not go out of business, either by filing for bankruptcy or by simply shutting down operations, thus leaving its customers stranded without an infrastructure and, depending on the type of cloud service used, even without their applications or data. This article attempts to address the issue of cloud provider viability, proposing some ways of mitigating the problem both from a technical and from a legal perspective. [less ▲]

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See detailCloud Providers Viability: How to Address it from an IT and Legal Perspective?
Bartolini, Cesare UL; El Kateb, Donia; Le Traon, Yves UL et al

in Electron Markets (2018), 28(1), 53-75

A major part of the commercial Internet is moving toward the cloud paradigm. This phenomenon has a drastic impact onthe organizational structures of enterprizes and introduces new challenges that must be ... [more ▼]

A major part of the commercial Internet is moving toward the cloud paradigm. This phenomenon has a drastic impact onthe organizational structures of enterprizes and introduces new challenges that must be properly addressed to avoid majorsetbacks. One such challenge is that of cloud provider viability, that is, the reasonable certainty that the Cloud ServiceProvider (CSP) will not go out of business, either by filing for bankruptcy or by simply shutting down operations, thusleaving its customers stranded without an infrastructure and, depending on the type of cloud service used, even withouttheir applications or data. This article attempts to address the issue of cloud provider viability, defining a possible way ofmodeling viability as a non-functional requirement and proposing some approaches that can be used to mitigate the problem,both from a technical and from a legal perspective. By introducing a structured perspective into the topic of cloud viability,describing the risks, factors and possible mitigators, the contribution of this work is twofold: it gives the customer a betterunderstanding to determine when it can rely on the cloud infrastructure on the long term and what precautions it should takein any case, and provides the CSP with means to address some of the viability issues and thus increase its customers’ trust. [less ▲]

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See detailCognitive estimation in the ideation phase of engineering design
Adolphy, Sebastian; Gericke, Kilian UL; Blessing, Lucienne UL

Poster (2010)

Estimation in its diverse forms is assumed to be relevant for problem solving in engineering design due to the inherent deficiencies in information availability and reliability. Nevertheless aside from ... [more ▼]

Estimation in its diverse forms is assumed to be relevant for problem solving in engineering design due to the inherent deficiencies in information availability and reliability. Nevertheless aside from some exception estimation as a method is hardly mentioned in standard literature on systematic approaches to engineering design like Pahl and Beitz. As well it is rarely deliberate addressed in engineering education. Engineering designers are expected to gain estimation competence by experience. Good performance in estimation and the development of estimation competence by hat is left to chance. Estimation as a problem solving strategy covers a wide range of activities on a continuous spectrum between the extremes of random guesses and highly mathematical statistics based approaches. Our research addresses estimation activities which are solely based on cognitive performance, without using specific mathematical procedures or technological support. Our current study is an explorative, qualitative protocol analysis of two idea creation meetings addressing different problems in the early phases of a technology-driven innovation project recorded by the DTRS7 organisation. The addressed research questions are: Where, how, why and what for is estimation used in engineering design? This analysis should give further insight in the not widely delineated topic of estimation in engineering design. [less ▲]

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See detailCollision-Free Navigation of Small UAVs in Complex Urban Environment
Annaiyan, Arun UL

Doctoral thesis (2018)

Small unmanned aerial vehicles (UAVs) are expected to become highly innovative solutions for all kind of tasks such as transport, surveillance, inspection or guidance, and many commercial ideas already ... [more ▼]

Small unmanned aerial vehicles (UAVs) are expected to become highly innovative solutions for all kind of tasks such as transport, surveillance, inspection or guidance, and many commercial ideas already exist. Herein, small multi rotor UAVs are preferred since they are easy to construct and to fly, at least in wide open spaces. However, many UAV business cases are foreseen in complex urban environments which are very challenging from the perspective of UAV flight. Our work focuses on the autonomous flight and collision-free navigation in an urban environment, where GPS is still considered for localization but where variations in the accuracy or temporary unavailability of GPS position data is explicitly considered. Herein, urban environments are challenging because they require flight nearby large structures and also nearby moving obstacles such as humans and other moving objects, at low altitudes or in very narrow spaces and thus also in areas where GPS (global positioning system) position data might temporarily be very inaccurate or even not available. Therefore we designed a custom stereo camera with adjustable base length for the perception of the possible potential obstacles in the unknown outdoor environment. In this context the optimal design and sensitivity parameters are investigated in outdoor experiments. Using the stereo images, graph based SLAM approach is used for online three dimensional mapping of the static and dynamic environment. For the memory efficiency incremental online loop closure detection using bag of words method is implemented here. By having the three dimensional map, the cost of the cell and its transition calculated in real time by the modified D* lite which will search and generate three dimensional collision free path planning. Experiments of the 3D mapping and collision free path planning are conducted using small UAV in outdoor scenario. The combined experimental results of real time mapping and path planning demonstrated that the three dimensional collision free path planning is able to handle the real time computational constraints while maintaining safety distance. [less ▲]

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See detailCombating non-communicable diseases: potentials and challenges for community health workers in a digital age, a narrative review of the literature
Mishra, Shiva Raj; Lygidakis, Charilaos UL; Neupane, Dinesh et al

in Health Policy and Planning (2019)

The use of community health workers (CHWs) has been explored as a viable option to provide home health education, counselling and basic health care, notwithstanding their challenges in training and ... [more ▼]

The use of community health workers (CHWs) has been explored as a viable option to provide home health education, counselling and basic health care, notwithstanding their challenges in training and retention. In this manuscript, we review the evidence and discuss how the digitalization affects the CHWs programmes for tackling non-communicable diseases (NCDs) in low- and middle-income countries (LMICs). We conducted a review of literature covering two databases: PubMED and Embase. A total of 97 articles were abstracted for full text review of which 26 are included in the analysis. Existing theories were used to construct a conceptual framework for understanding how digitalization affects the prospects of CHW programmes for NCDs. The results are divided into two themes: (1) the benefits of digitalization and (2) the challenges to the prospects of digitalization. We also conducted supplemental search in non-peer reviewed literature to identify and map the digital platforms currently in use in CHW programmes. We identified three benefits and three challenges of digitalization. Firstly, it will help improve the access and quality of services, notwithstanding its higher establishment and maintenance costs. Secondly, it will add efficiency in training and personnel management. Thirdly, it will leverage the use of data generated across grass-roots platforms to further research and evaluation. The challenges posed are related to funding, health literacy of CHWs and systemic challenges related to motivating CHWs. Several dozens of digital platforms were mapped, including mobile-based networking devices (used for behavioural change communication), Web-applications (used for contact tracking, reminder system, adherence tracing, data collection and decision support), videoconference (used for decision support) and mobile applications (used for reminder system, supervision, patients’ management, hearing screening and tele-consultation). The digitalization efforts of CHW programmes are afflicted by many challenges, yet the rapid technological penetration and acceptability coupled with the gradual fall in costs constitute encouraging signals for the LMICs. Both CHWs interventions and digital technologies are not inexpensive, but they may provide better value for the money when applied at the right place and time. [less ▲]

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See detailA combined extended finite element and level set method for biofilm growth
Duddu, Ravindra; Bordas, Stéphane UL; Chopp, David et al

in International Journal for Numerical Methods in Engineering (2008), 74(5), 848-870

This paper presents a computational technique based on the extended finite element method (YFEM) and the level set method for the growth of biofilms. The discontinuous-derivative enrichment of the ... [more ▼]

This paper presents a computational technique based on the extended finite element method (YFEM) and the level set method for the growth of biofilms. The discontinuous-derivative enrichment of the standard finite element approximation eliminates the need for the finite element mesh to coincide with the biofilm-fluid interface and also permits the introduction of the discontinuity in the normal derivative of the substrate concentration field at the biofilm-fluid interface. The XFEM is coupled with a comprehensive level set update scheme with velocity extensions, which makes updating the biofilm interface fast and accurate without need for remeshing. The kinetics of biofilms are briefly given and the non-linear strong and weak forms are presented. The non-linear system of equations is solved using a Newton-Raphson scheme. Example problems including 1D and 2D biofilm growth are presented to illustrate the accuracy and utility of the method. The 1D results we obtain are in excellent agreement with previous 1D results obtained using finite difference methods. Our 2D results that simulate finger formation and finger-tip splitting in biofilms illustrate the robustness of the present computational technique. [less ▲]

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See detailA combined parking and carpooling policy: the case of the University of Luxembourg
Sprumont, François UL; Viti, Francesco UL; Ouzdi, Youssef UL

Scientific Conference (2015, May 29)

With 2586km2, Luxembourg is the 7th European smallest country in Europe. Despite its small size this country is facing important mobility challenges. Out of the 380 000 available jobs in the country ... [more ▼]

With 2586km2, Luxembourg is the 7th European smallest country in Europe. Despite its small size this country is facing important mobility challenges. Out of the 380 000 available jobs in the country, nearly 43% of them are occupied by cross borders workers. These 165 000 cross borders traveling every day from France, Belgium and Germany generate an important pressure on the transport infrastructures. Because 89% of the cross-borders workers and 74% of the resident workers commute by car, the road system, at peak hours, reaches saturation. In order to decrease the pressure (in term of commuting flow, residential prices, etc.) on Luxembourg City and to reach a more balanced polycentric development across the country the development of Belval has been decided by the government. This new-town which is located 20km south-west of Luxembourg-City will attract economic activity and residential units. The University of Luxembourg will be one of institutions relocating most of its infrastructure in Belval. Without any doubts, this workplace relocation will greatly affect the University staff commuting mobility. In accordance to any public institution or large enterprise in this country, the University is more and more committed to reduce the carbon footprint related to the staff and students commuting behavior. The MODU (national sustainable mobility strategy) defines strong modal split objectives and the number of parking spaces available for the university on Belval site will rely on this national objective. So far, few scientific contributions analyzed the accessibility variation for car and Public Transport (PT) on important worker’s’ population considering relocation actions of this size. GIS tools and visualization techniques will permit to quantify the car and public transport accessibility vari ation due to the University move to Belval. The scientific contribution of this article lies in the relation between the car & PT accessibility and the development of Travel Demand Management (TDM) measures. Indeed, an innovative Parking Management Scheme (PMS) integrating car & PT accessibility to the new campus as well as carpooling use among the staff members will be presented. Our aim is to develop a mobility credit scheme system where users could use points to park their car or use the public transport system. Soft modes might collect additional points that could serve to get gifts or even cash back. Indeed, the objective is to reach a pragmatic parking policy that lead Single Occupancy Vehicle (SOV) to shift, first, to soft modes, then, to public transport and finally to carpooling. The key is the relation between the different travel modes and their existing incentives or disincentives. This approach might help other major private or public institutions to define optimum subsidy strategies regarding their parking and staff’s public seasonal ticket costs. [less ▲]

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See detailCombining demand management and merge control in an equilibrium network model
Viti, Francesco UL; Huang, Wei; Smith, Mike J.

Scientific Conference (2013)

Equilibrium models under congested traffic conditions, and especially those addressing blocking back, are very useful to estimate the demand conditions that ITS policies should be able to manage, for ... [more ▼]

Equilibrium models under congested traffic conditions, and especially those addressing blocking back, are very useful to estimate the demand conditions that ITS policies should be able to manage, for instance to maintain congestion within controlled areas and avoiding that they further spillback and cause more serious and/or less controllable congestion states. The objective of this paper is to supplement the equilibrium model, developed by the authors in recent research, with a more thorough analysis of merge behaviour, especially in cases of blocked nodes. Regulating the merger behaviour together with the demand pattern can lead to certain desired stationary states. It has a great practical significance when congestion is inevitable, while demand management and merge control are able to retain queues and spill-backs within the local area. [less ▲]

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See detailA comparative study of task assignment and path planning methods for multi-UGV missions
Thunberg, Johan UL; Anisi, D.; Ögren, P.

in Optimization and Cooperative Control Strategies (2009)

Many important problems involving a group of unmanned ground vehicles (UGVs) are closely related to the multi traviling salesman problem (m-TSP). This paper comprises a comparative study of a number of ... [more ▼]

Many important problems involving a group of unmanned ground vehicles (UGVs) are closely related to the multi traviling salesman problem (m-TSP). This paper comprises a comparative study of a number of algorithms proposed in the litterature to solve m-TSPs occuring in robotics. The investigated algoritms include two mixed integer linear programming (MILP) formulations, a market based approach (MA), a Voronoi partition step (VP) combined with the local search used in MA, and a deterministic and a stocastic version of the granular tabu search (GTS). To evaluate the algoritms, an m-TSP is derived from a planar environment with polygonal obstacles and uniformly distributed targets and vehicle positions. The results of the comparison indicate that out of the decentralized approaches, the MA yield good solutions but requires long computation times, while VP is fast but not as good. The two MILP approaches suffer from long computation times, and poor results due to the decomposition of the assignment and path planning steps. Finally, the two GTS algorithms yield good results in short times with inputs from MA as well as the much faster VP. Thus the best performing centralized approach is the GTS in combination with the VP. [less ▲]

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See detailA comparison between conventional Earth Observation Satellites and CubeSats; Requirements, Capabilities and Data Quality
Backes, Dietmar UL; Hassani, Saif Alislam UL; Teferle, Felix Norman UL et al

Scientific Conference (2019, September 11)

From its early beginning as an educational tool in 1999, cubesats have evolved into a popular platform for technology demonstrations and scientific instruments. Ideas and innovations sparked from an ... [more ▼]

From its early beginning as an educational tool in 1999, cubesats have evolved into a popular platform for technology demonstrations and scientific instruments. Ideas and innovations sparked from an enthusiastic community led to the development of new Earth Observation (EO) technology concepts based on large constellations of satellites with high-resolution optical imagers previously considered as infeasible. Probably the most significant constellation today is deployed by Planet who are currently operating a fleet larger than 120 3U Dove satellites, which provide an imaging service with up to 3m Ground Sample Distance (GSD). The number of low-cost EO Cubesat systems is constantly increasing. However, for a number of reasons there still seems to be a reluctance to use such data for many EO applications. A better understanding of the capabilities of the current generation of small Cubesats compared to the traditional well-established bigger operational missions of high and medium resolution EO satellites is required. What are the critical capabilities and quality indicators? Due to the limited size and weight of Cubesats, critical system components, e.g. for navigation and communication, always compete with operational payloads such as optical camera/sensor systems. A functional EO system requires balanced payload, which provides adequate navigational capabilities, that match the requirements of the optical imagers (camera) deployed with the system. This study reviews the current performance and capabilities of Cubesats for optical EO and compares them to the capabilities of conventional, dedicated high and medium resolution EO systems. We summarise key performance parameters and quality indicators to evaluate the difference between the systems. An empirical study compares recent very high-resolution (VHR) imagery from big EO satellite missions with available images from Cubesats for the use case in disaster monitoring. Small and agile Nanosatellites or Cubesats already show remarkable performance. Although it is not expected that their performance and capability will match those of current bigger EO satellite missions, they are expected to provide a valuable tool for EO and remote sensing, in particular for downstream industry applications. [less ▲]

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See detailComparison of Machine Learning techniques for atmospheric pollutant monitoring in a Kraft pulp mill
Sainlez, Matthieu UL; Heyen, Georges

Scientific Conference (2011, November)

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data ... [more ▼]

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data related to a Kraft recovery boiler, we consider a regression problem in which we are trying to predict the value of a continuous variable. Generalization is done on the worst case configuration possible to make sure the model is adequate: the training period concerns stationary operations while test periods mainly focus on NOx emissions during transient operations. This comparison involves neural network techniques (i.e., static multilayer perceptron and dynamic NARX network), tree-based methods and multiple linear regression. We illustrate the potential of a dynamic neural approach compared to the others in this prediction task. [less ▲]

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See detailComparison of metadata quality in open data portals using the Analytic Hierarchy Process
Kubler, sylvain; Robert, Jérémy UL; Neumaier, Sebastian et al

in Government Information Quarterly (2018)

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See detailA Comparison of Network Reconstruction Methods for Chemical Reaction Networks
Ward, C.; Yeung, E.; Brown, T. et al

in The proceedings of the Third International Conference on Foundations of Systems Biology in Engineering (FOSBE 2009) (2009)

Chemical reaction networks model biological interactions that regulate the functional properties of a cell; these networks characterize the chemical pathways that result in a particular phenotype. One ... [more ▼]

Chemical reaction networks model biological interactions that regulate the functional properties of a cell; these networks characterize the chemical pathways that result in a particular phenotype. One goal of systems biology is to understand the structure of these networks given concentration measurements of various species in the system. Previous work has shown that this network reconstruction problem is fundamentally impossible, even for simplified linear models, unless a particular experiment design is followed. Nevertheless, reconstruction algorithms have been developed that attempt to approximate a solution using sparsity or similar heuristics. This work compares, in silico, the results of three of these methods in situations where the necessary experiment design has been followed, and it illustrates the degradation of each method as increasing noise levels are added to the data. [less ▲]

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See detailComparison of recently developed recovery type discretization error estimators for the extended finite element method
Ródenas, J. J.; Duflot, Marc; Bordas, Stéphane UL et al

in Schrefler, B A; Perego, U (Eds.) 8th World Congress on Computational Mechanics (WCCM8). 5th.European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2008) (2008)

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See detailA Comparison of Semantic Models for Noninterference
van der Meyden, R.; Zhang, Chenyi UL

in Theoretical Computer Science (2010), 411(47), 41234147

The literature on definitions of security based on causality-like notions such as noninterference has used several distinct semantic models for systems. Early work was based on state machine and trace-set ... [more ▼]

The literature on definitions of security based on causality-like notions such as noninterference has used several distinct semantic models for systems. Early work was based on state machine and trace-set definitions; more recent work has dealt with definitions of security in two distinct process algebraic settings. Comparisons between the definitions has been carried out mainly within semantic frameworks. This paper studies the relationship between semantic frameworks, by defining mappings between a number of semantic models and studying the relationship between notions of noninterference under these mappings. [less ▲]

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See detailComparison of Several RANS Modelling for the Pavia TRIGA Mark II Research Reactor
Introini, Carolina; Cammi, Antonio; Lorenzi, Stefano et al

in Journal of Nuclear Engineering and Radiation Science (2018)

Aim of this work is the comparison of different turbulent models based on the Reynolds Averaged Navier-Stokes (RANS) equations in order to find out which model is the most suitable for the study of the ... [more ▼]

Aim of this work is the comparison of different turbulent models based on the Reynolds Averaged Navier-Stokes (RANS) equations in order to find out which model is the most suitable for the study of the channel thermal-hydraulics of the TRIGA Mark II reactor. Only the steady state behaviour (i.e. the full power stationary operational conditions) of the reactor has been considered. To this end, the RAS (Reynolds-Averaged Simulation) models available in the open source CFD software OpenFOAM have been applied to the most internal channel of the TRIGA and assessed against a Large Eddy Simulation (LES) model. The results of the latter approach, expressed in terms of axial velocity, turbulent viscosity, turbulent kinetic energy, and temperature have been compared with the results obtained by the RAS models available in OpenFOAM (k − ε, k − ω and Reynolds Stress Transport). Heat transfer is taken into account as well by means of the turbulent energy diffusivity parameter. The simulation results demonstrate how, amongst the RAS models, the k − ω SST is the one whose results are closer to the LES simulation. This model seems to be the best one for the treatment of turbulent flow within the TRIGA subchannel, offering a good compromise between accuracy and computational requirements. Since it is much less expensive than an LES model, it can be applied even to full core calculation, in order to obtain accurate results with less computational effort. [less ▲]

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See detailComparison of Several RANS Modelling for the Pavia TRIGA Mark II Research Reactor
Introini, Carolina; Baroli, Davide UL; Peters, Bernhard UL

Poster (2017)

In this study, a detailed analysis of the turbulent regime within the core of the Pavia TRIGA Mark II reactor is perfomed by means of an in-depth comparison of the RAS (Reynolds-Averaged Simulation ... [more ▼]

In this study, a detailed analysis of the turbulent regime within the core of the Pavia TRIGA Mark II reactor is perfomed by means of an in-depth comparison of the RAS (Reynolds-Averaged Simulation) turbulence models implemented in OpenFOAM. Aim of this analysis is to give some important information with respect to the flow regime within the core. The performance of the various models is tested against a LES (Large Eddy Simulation) of the innermost channel. [less ▲]

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See detailA comparison of two meso-models for dry-woven fabrics and their multiscale equivalents
Beex, Lars UL; Duflot, Marc; Adam, Laurent

Scientific Conference (2016, April)

In this presentation, an X-braced spring mesomodel will be compared to a mesomodel in which the diagonal springs are replaced by rotational springs. The results are signi cantly di fferent, but some ... [more ▼]

In this presentation, an X-braced spring mesomodel will be compared to a mesomodel in which the diagonal springs are replaced by rotational springs. The results are signi cantly di fferent, but some disadvantages of the use of rotational springs will also be mentioned. A substantial part of the presentation will furthermore be dedicated to the multiscale quasicontinuum method to upscale the mesomodels in order to achieve e fficient macroscale computations. macroscale computations [less ▲]

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