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141.
Tim Van Gestel Feng Han Doris Sebold Hans Peter Buchkremer Detlev St?ver 《Microsystem Technologies》2011,17(2):233-242
A solid oxide fuel cell (SOFC) with a thin-film yttria-stabilized zirconia (YSZ) electrolyte was developed and tested. This
novel SOFC shows a similar multilayer set-up as other current anode-supported SOFCs and is composed of a Ni/8YSZ anode, a
gas-tight 8YSZ electrolyte layer, a dense Sr-diffusion barrier layer and a LSCF cathode. To increase the power density and
lower the SOFC operating temperature, the thickness of the electrolyte layer was reduced from around 10 μm in current cells
to 1 μm, using a nanoparticle deposition method. By using the novel 1 μm electrolyte layer, the current density of our SOFC
progressed to 2.7, 2.1 and 1.6 A/cm2 at operation temperatures of 800, 700 and 650°C, respectively, and out-performs all similar cells reported to date in the
literature. An important consideration is also that cost-effective dip-coating and spin-coating methods are applied for the
fabrication of the thin-film electrolyte. Processing of 1 μm layers on the very porous anode substrate material was initially
experienced as very difficult and therefore 8YSZ nanoparticle coatings were developed and optimized on porous 8YSZ model substrates
and transferred afterwards to regular anode substrates. In this paper, the preparation of the novel SOFC is shown and its
morphology is illustrated with high resolution SEM pictures. Further, the performance in a standard SOFC test is demonstrated. 相似文献
142.
As transistors shrink and processors trend toward low power, maintaining precise digital behavior grows more expensive. Replacing digital units with analog equivalents sometimes allows similar computation to be performed at higher speed using less power. As a case study in mixed-signal approximate computation, the authors describe an enhanced neural prediction algorithm and its efficient analog implementation. 相似文献
143.
TU GuoFang LIU JianJun ZHANG Can GAO ShaoShuai & LI ShiDong School of Information Science Engineering Graduate University of Chinese Academy of Sciences Beijing China State Key Laboratory of Information Security National Institute of St ards Technology Gaithersburg MD USA 《中国科学:信息科学(英文版)》2010,(1):1-17
Joint source-channel coding/decoding (JSCC/JSCD) techniques in flow media communications have become a state-of-the-art and one of the challenging research subjects in the spatial communication area. They have great application prospective and deep impact in various manned space flights, satellite missions, mobile radio communications and deep-space explorations. In the last few years, there have been influential achievements in JSCC/JSCD studies. This paper aims at an introduction to the basic principles o... 相似文献
144.
Variational implicit surface meshing 总被引:1,自引:0,他引:1
In this paper, we propose a new algorithm to mesh implicit surfaces which produces meshes both with a good triangle aspect ratio as well as a good approximation quality. The number of vertices of the output mesh is defined by the end-user. For this goal, we perform a two-stage processing: an initialization step followed by an iterative optimization step. The initialization step consists in capturing the surface topology and allocating the vertex budget. The optimization algorithm is based on a variational vertices relaxation and triangulation update. In addition a gradation parameter can be defined to adapt the mesh sampling to the curvature of the implicit surface. We demonstrate the efficiency of the approach on synthetic models as well as real-world acquired data, and provide comparisons with previous approaches. 相似文献
145.
Rafael Antonello Stênio Fernandes Josilene Moreira Paulo Cunha Carlos Kamienski Djamel Sadok 《Multimedia Systems》2009,15(1):33-47
Virtual Worlds (VW), such as Massive Multiplayer Online Social Games, have been gaining increasing attention in the last few
years, mainly due to the new way users interact with them. However, little effort has been devoted to understand their traffic
profile and the implications to the traffic management area. With the current growing rate of VWs’ usage, their traffic demand
could eventually impose a significant burden on the operation of a typical Internet Service Provider (ISP) network. In this
paper, we seek to understand the traffic behavior of an increasingly popular VW application, namely Second Life (SL), from
both the connection and network level perspectives. We also show results of a traffic analysis of a SL client, when an avatar
performs different actions in the VW, at different places and under different network conditions. Our results show that SL
makes intensive use of network resources (mostly bandwidth), since the capacity needed for having a full SL experience (listening
to live music) may reach 500 kbps. We then extend the traffic analysis work on SL by providing analytical models for its traffic
profile. We aim at helping the network management and planning area to estimate the impact of an intense use of such VW on
access links or core networks. Such synthetic models are also useful to the networking research community for the use in network
simulations. 相似文献
146.
A comprehensive quality model for service-oriented systems 总被引:2,自引:0,他引:2
In a service-oriented system, a quality (or Quality of Service) model is used (i) by service requesters to specify the expected
quality levels of service delivery; (ii) by service providers to advertise quality levels that their services achieve; and
(iii) by service composers when selecting among alternative services those that are to participate in a service composition.
Expressive quality models are needed to let requesters specify quality expectations, providers advertise service qualities,
and composers finely compare alternative services. Having observed many similarities between various quality models proposed
in the literature, we review these and integrate them into a single quality model, called QVDP. We highlight the need for
integration of priority and dependency information within any quality model for services and propose precise submodels for
doing so. Our intention is for the proposed model to serve as a reference point for further developments in quality models
for service-oriented systems. To this aim, we extend the part of the UML metamodel specialized for Quality of Service with
QVDP concepts unavailable in UML.
Ivan J. Jureta has, after graduating, summa cum laude, received the Master in Management and Master of International Management, respectively, at the Université de Louvain, Belgium, and the London School of Economics, both in 2005. He is currently completing his Ph.D. thesis at the University of Namur, Belgium, under Prof. Stéphane Faulkner’s supervision. His thesis focuses on quality management of adaptable and open service-oriented systems enabling the Semantic Web. Caroline Herssens received a Master Degree in Computer Science in 2005 at the Université de Louvain. In 2006, she graduated a Master in Business and Administration from the University of Louvain, with a supply chain management orientation. She is currently a teaching and research assistant and has started a Ph.D. thesis at the information systems research unit at Université de Louvain. Her research interests comprise service-oriented computing, conceptual modeling and information systems engineering. Stéphane Faulkner is an Associate Professor in Technologies and Information Systems at the University of Namur (FUNDP) and an Invited Professor at the Louvain School of Management of the Université de Louvain (UCL). His current research interests revolve around requirements engineering and the development of modeling notations, systematic methods and tool support for the development of multi-agent systems, database and information systems. 相似文献
Stéphane FaulknerEmail: |
Ivan J. Jureta has, after graduating, summa cum laude, received the Master in Management and Master of International Management, respectively, at the Université de Louvain, Belgium, and the London School of Economics, both in 2005. He is currently completing his Ph.D. thesis at the University of Namur, Belgium, under Prof. Stéphane Faulkner’s supervision. His thesis focuses on quality management of adaptable and open service-oriented systems enabling the Semantic Web. Caroline Herssens received a Master Degree in Computer Science in 2005 at the Université de Louvain. In 2006, she graduated a Master in Business and Administration from the University of Louvain, with a supply chain management orientation. She is currently a teaching and research assistant and has started a Ph.D. thesis at the information systems research unit at Université de Louvain. Her research interests comprise service-oriented computing, conceptual modeling and information systems engineering. Stéphane Faulkner is an Associate Professor in Technologies and Information Systems at the University of Namur (FUNDP) and an Invited Professor at the Louvain School of Management of the Université de Louvain (UCL). His current research interests revolve around requirements engineering and the development of modeling notations, systematic methods and tool support for the development of multi-agent systems, database and information systems. 相似文献
147.
Samuel Aupetit Virginie Gallier Jacques Riff Stéphane Espié Flavien Delgehier 《Ergonomics》2016,59(8):1109-1120
This article sets out to identify the typical risky situations experienced by novice motorcyclists in the real world just after licensing. The procedure consists of a follow-up of six novices during their first two months of riding with their own motorbike instrumented with cameras. The novices completed logbooks on a daily basis in order to identify the risky situations they encountered, and were given face-to-face interviews to identify the context and their shortcomings during the reported events. Data show a large number of road configurations considered as risky by the riders (248 occurrences), especially during the first two weeks. The results revealed that a lack of hazard perception skills contributed to the majority of these incidents. These situations were grouped together to form clusters of typical incident scenarios on the basis of their similarities. The most frequent scenario corresponds to a lane change in dense traffic (15% of all incidents). The discussion shows how this has enhanced our understanding of novice riders’ behaviour and how the findings can improve training and licensing. Lastly, the main methodological limitations of the study and some guidelines for improving future naturalistic riding studies are presented.
Practitioner Summary:
This article aims to identify the risky situations of novice motorcyclists in real roads. Two hundred forty-eight events were recorded and 13 incident scenarios identified. Results revealed that a lack of hazard perception contributed to the majority of these events. The most frequent scenario corresponds to a lane change in dense traffic. 相似文献
148.
The importance of traceability in software development has long been recognized, not only for reasons of legality and certification, but also to enable the development itself. At the same time, organizations are known to struggle to live up to traceability requirements, and there is an identified lack of studies on traceability practices in the industry, not least in the area of tooling and infrastructure. This paper presents, investigates and discusses Eiffel, an industry developed solution designed to provide real time traceability in continuous integration and delivery. The traceability needs of industry professionals are also investigated through interviews, providing context to that solution. It is then validated through further interviews, a comparison with previous traceability methods and a review of literature. It is found to address the identified traceability needs and found in some cases to reduce traceability data acquisition times from days to minutes, while at the same time alternatives offering comparable functionality are lacking. In this work, traceability is shown not only to be an important concern to engineers, but also regarded as a prerequisite to successful large scale continuous integration and delivery. At the same time, promising developments in technical infrastructure are documented and clear differences in traceability mindset between separate industry projects is revealed. 相似文献
149.
Road‐Centered Map‐Aided Localization for Driverless Cars Using Single‐Frequency GNSS Receivers
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Zui Tao Philippe Bonnifait Vincent Frémont Javier Ibanez‐Guzman Stéphane Bonnet 《野外机器人技术杂志》2017,34(5):1010-1033
Accurate localization with high availability is a key requirement for autonomous vehicles. It remains a major challenge when using automotive sensors such as single‐frequency Global Navigation Satellite System (GNSS) receivers, a lane detection camera, and proprioceptive sensors. This paper describes a method that enables the estimation of stand‐alone single‐frequency GNSS errors by integrating the measurements from a forward‐looking camera matched with lane markings stored in a digital map. It includes a parameter identification method for a shaping model, which is evaluated using experimental data. An algebraic observability study is then conducted to prove that the proposed state vector is fully observable in a road‐oriented frame. This observability property is the basis to develop a road‐centered Extended Kalman filter (EKF) that can maintain the observability of every component of the state vector on any road, whatever its orientation. To accomplish this, the filter needs to handle road changes, which it does using bijective transformations. The filter was implemented and tested intensely on an experimental vehicle for driverless valet parking services. Field results have shown that the performance of the estimation process is better than solutions based on EKF implemented in a fixed working frame. The proposed filter guarantees that the drift along the road direction remains bounded. This is very important when the vehicle navigates autonomously. Furthermore, the road‐centered modeling improves the accuracy, consistency, and robustness of the localization solver. 相似文献
150.
Mohammed Moumnassi Salim Belouettar Éric Béchet Stéphane P.A. Bordas Didier Quoirin Michel Potier-Ferry 《Computer Methods in Applied Mechanics and Engineering》2011,200(5-8):774-796
In this paper, we present some novel results and ideas for robust and accurate implicit representation of geometric surfaces in finite element analysis. The novel contributions of this paper are threefold: (1) describe and validate a method to represent arbitrary parametric surfaces implicitly; (2) represent arbitrary solids implicitly, including sharp features using level sets and boolean operations; (3) impose arbitrary Dirichlet and Neumann boundary conditions on the resulting implicitly defined boundaries. The methods proposed do not require local refinement of the finite element mesh in regions of high curvature, ensure the independence of the domain’s volume on the mesh, do not rely on boundary regularization, and are well suited to methods based on fixed grids such as the extended finite element method (XFEM). Numerical examples are presented to demonstrate the robustness and effectiveness of the proposed approach and show that it is possible to achieve optimal convergence rates using a fully implicit representation of object boundaries. This approach is one step in the desired direction of tying numerical simulations to computer aided design (CAD), similarly to the isogeometric analysis paradigm. 相似文献