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51.
Anselm Grundhöfer Daniel Kurz Sebastian Thiele Oliver Bimber 《The Visual computer》2010,26(9):1167-1176
In this article we show how temporal backdrops that alternately change their color rapidly at recording rate can aid chroma
keying by transforming color spill into a neutral background illumination. Since the chosen colors sum up to white, the chromatic
(color) spill component is neutralized when integrating over both backdrop states. The ability to separate both states additionally
allows to compute high-quality alpha mattes. Besides the neutralization of color spill, our method is invariant to foreground
colors and supports applications with real-time demands. In this article, we explain different realizations of temporal backdrops
and describe how keying and color spill neutralization are carried out, how artifacts resulting from rapid motion can be reduced,
and how our approach can be implemented to be compatible with common real-time post-production pipelines. 相似文献
52.
Christian Liebchen Michael Schachtebeck Anita Schöbel Sebastian Stiller André Prigge 《Computers & Operations Research》2010,37(5):857-868
In the past, much research has been dedicated to compute optimum railway timetables. A typical objective has been the minimization of passenger waiting times. But only the planned nominal waiting times have been addressed, whereas delays as they occur in daily operations have been neglected. Delays have been rather treated mainly in an online context and solved as a separate optimization problem, called delay management.We provide the first computational study which aims at computing delay resistant periodic timetables. In particular we assess the delay resistance of a timetable by evaluating it subject to several delay scenarios to which optimum delay management will be applied.We arrive at computing delay resistant timetables by selecting a new objective function which we design to be somehow in the middle of the traditional simple timetabling objective and the sophisticated delay management objective. This is a slight extension of the concept of “light robustness” (LR) as it has been proposed by Fischetti and Monaci [2006. Robust optimization through branch-and-price. In: Proceedings of AIRO]. Moreover, in our application we are able to provide accurate interpretations for the ingredients of LR. We apply this new technique to real-world data of a part of the German railway network of Deutsche Bahn AG. Our computational results suggest that a significant decrease of passenger delays can be obtained at a relatively small price of robustness, i.e. by increasing the nominal travel times of the passengers. 相似文献
53.
Broadcast semantics poses significant challenges over point-to-point communication when it comes to formal modelling and analysis. Current approaches to analysing broadcast networks have focused on fixed connectivities, but this is unsuitable in the case of wireless networks where the dynamically changing network topology is a crucial ingredient. In this paper, we develop a static analysis that automatically constructs an abstract transition system, labelled by actions and connectivity information, to yield a mobility-preserving finite abstraction of the behaviour of a network expressed in a process calculus with asynchronous local broadcast. Furthermore, we use model checking based on a 3-valued temporal logic to distinguish network behaviour which differs under changing connectivity patterns. 相似文献
54.
Making it easier for older people to talk to smart homes: the effect of early help prompts 总被引:1,自引:0,他引:1
K. Maria Wolters Klaus-Peter Engelbrecht Florian Gödde Sebastian Möller Anja Naumann Robert Schleicher 《Universal Access in the Information Society》2010,9(4):311-325
It is well known that help prompts shape how users talk to spoken dialogue systems. This study investigated the effect of
help prompt placement on older users’ interaction with a smart home interface. In the dynamic help condition, help was only
given in response to system errors; in the inherent help condition, it was also given at the start of each task. Fifteen older
and sixteen younger users interacted with a smart home system using two different scenarios. Each scenario consisted of several
tasks. The linguistic style users employed to communicate with the system (interaction style) was measured using the ratio of commands to the overall utterance length (keyword ratio) and the percentage of content
words in the user’s utterance that could be understood by the system (shared vocabulary). While the timing of help prompts
did not affect the interaction style of younger users, it was early task-specific help supported older users in adapting their
interaction style to the system’s capabilities. Well-placed help prompts can significantly increase the usability of spoken
dialogue systems for older people. 相似文献
55.
IntroductionAn important quality of association rules is novelty. However, evaluating rule novelty is AI-hard and has been a serious challenge for most data mining systems.ObjectiveIn this paper, we introduce functional novelty, a new non-pairwise approach to evaluating rule novelty. A functionally novel rule is interesting as it suggests previously unknown relations between user hypotheses.MethodsWe developed a novel domain-driven KDD framework for discovering functionally novel association rules. Association rules were mined from cardiovascular data sets. At post-processing, domain knowledge-compliant rules were discovered by applying semantic-based filtering based on UMLS ontology. Their knowledge compliance scores were computed against medical knowledge in Pubmed literature. A cardiologist explored possible relationships between several pairs of unknown hypotheses. The functional novelty of each rule was computed based on its likelihood to mediate these relationships.ResultsHighly interesting rules were successfully discovered. For instance, common rules such as diabetes mellitus?coronary arteriosclerosis was functionally novel as it mediated a rare association between von Willebrand factor and intracardiac thrombus.ConclusionThe proposed post-mining domain-driven rule evaluation technique and measures proved to be useful for estimating candidate functionally novel rules with the results validated by a cardiologist. 相似文献
56.
Carlos A. Jara Francisco A. Candelas Fernando Torres Sebastian Dormido Francisco Esquembre Oscar Reinoso 《Computers & Education》2009
Web-based learning environments are becoming increasingly popular in higher education. One of the most important web-learning resources is the virtual laboratory (VL), which gives students an easy way for training and learning through the Internet. Moreover, on-line collaborative communication represents a practical method to transmit the knowledge and experience from the teacher to students overcoming physical distance and isolation. Considering these facts, the authors of this document have developed a new dynamic collaborative e-learning system which combines the main advantages of virtual laboratories and collaborative learning practices. In this system, the virtual laboratories are based on Java applets which have embedded simulations developed in Easy Java Simulations (EJS), an open-source tool for teachers who do not need complex programming skills. The collaborative e-learning is based on a real-time synchronized communication among these Java applets. Therefore, this original approach provides a new tool which integrates virtual laboratories inside a synchronous collaborative e-learning framework. This paper describes the main features of this system and its successful application in a distance education environment among different universities from Spain. 相似文献
57.
Sebastian Dörn 《Information Processing Letters》2009,109(6):325-328
In this paper we give tight quantum query complexity bounds of some important linear algebra problems. We prove Θ(n2) quantum query bounds for verify the determinant, rank, matrix inverse and the matrix power problem. 相似文献
58.
59.
Thomas Neumann Matthias Bender Sebastian Michel Ralf Schenkel Peter Triantafillou Gerhard Weikum 《Distributed and Parallel Databases》2009,26(1):3-27
Top-k query processing is a fundamental building block for efficient ranking in a large number of applications. Efficiency is a
central issue, especially for distributed settings, when the data is spread across different nodes in a network. This paper
introduces novel optimization methods for top-k aggregation queries in such distributed environments. The optimizations can be applied to all algorithms that fall into the
frameworks of the prior TPUT and KLEE methods. The optimizations address three degrees of freedom: 1) hierarchically grouping
input lists into top-k operator trees and optimizing the tree structure, 2) computing data-adaptive scan depths for different input sources, and
3) data-adaptive sampling of a small subset of input sources in scenarios with hundreds or thousands of query-relevant network
nodes. All optimizations are based on a statistical cost model that utilizes local synopses, e.g., in the form of histograms,
efficiently computed convolutions, and estimators based on order statistics. The paper presents comprehensive experiments,
with three different real-life datasets and using the ns-2 network simulator for a packet-level simulation of a large Internet-style
network. 相似文献
60.
Ahmed Fadl Zongqin Zhang Sebastian Geller Jonas Tölke Manfred Krafczyk Donna Meyer 《Microsystem Technologies》2009,15(9):1379-1387
The efficiency of the valve-less rectification micropump depends primarily on the microfluidic diodicity (the ratio of the
backward pressure drop to the forward pressure drop). In this study, different rectifying structures, including the conventional
structures (nozzle/diffuser and Tesla structures), were investigated at very low Reynolds numbers (between 0.2 and 60). The
rectifying structures were characterized with respect to their design, and a numerical approach was illustrated to calculate
the diodicity for the rectifying structures. In this study, the microfluidic diodicity was evaluated numerically for different
rectifying structures including half circle, semicircle, heart, triangle, bifurcation, nozzle/diffuser, and Tesla structures.
The Lattice Boltzmann Method (LBM) was utilized as a numerical method to simulate the fluid flow in the microscale. The results
suggest that at very low Reynolds number flow, rectification and multifunction micropumping may be achievable by using a number
of the presented structures. The results for the conventional structures agree with the reported results. 相似文献