466 research outputs found
XML Document Adaptation Queries (XDAQ)
Adaptive web applications combine data retrieval on the web with reasoning so as to generate context dependent contents. The data is retrieved either as content or as context specifications. Content data is, for example, fragments of a textbook or e-commerce catalogue, whereas context data is, for example, a user model or a device profile. Current adaptive web applications are often implemented using ad hoc and heterogeneous techniques. This paper describes a novel approach called āXML Document Adaptation Queries (XDAQ)ā requiring less heterogeneous software components. The approach is based on using a web query language for data retrieval (content as well as context) and on a novel generic formalism to express adaptation. The approach is generic in the sense that it is applicable with all web query and transformation languages, for example with XQuery and XSLT
Rapidly-exploring Random Belief Trees for Motion Planning Under Uncertainty
In this paper we address the problem of motion
planning in the presence of state uncertainty, also known as
planning in belief space. The work is motivated by planning
domains involving nontrivial dynamics, spatially varying measurement
properties, and obstacle constraints. To make the
problem tractable, we restrict the motion plan to a nominal
trajectory stabilized with a linear estimator and controller. This
allows us to predict distributions over future states given a candidate
nominal trajectory. Using these distributions to ensure
a bounded probability of collision, the algorithm incrementally
constructs a graph of trajectories through state space, while
efficiently searching over candidate paths through the graph at
each iteration. This process results in a search tree in belief
space that provably converges to the optimal path. We analyze
the algorithm theoretically and also provide simulation results
demonstrating its utility for balancing information gathering to
reduce uncertainty and finding low cost paths.United States. Office of Naval Research (MURI N00014-09-1-1052
State estimation for aggressive flight in GPS-denied environments using onboard sensing
In this paper we present a state estimation method based on an inertial measurement unit (IMU) and a planar laser range finder suitable for use in real-time on a fixed-wing micro air vehicle (MAV). The algorithm is capable of maintaing accurate state estimates during aggressive flight in unstructured 3D environments without the use of an external positioning system. Our localization algorithm is based on an extension of the Gaussian Particle Filter. We partition the state according to measurement independence relationships and then calculate a pseudo-linear update which allows us to use 20x fewer particles than a naive implementation to achieve similar accuracy in the state estimate. We also propose a multi-step forward fitting method to identify the noise parameters of the IMU and compare results with and without accurate position measurements. Our process and measurement models integrate naturally with an exponential coordinates representation of the attitude uncertainty. We demonstrate our algorithms experimentally on a fixed-wing vehicle flying in a challenging indoor environment
Towards a Declarative Query and Transformation Language for XML and Semistructured Data: Simulation Unification
The growing importance of XML as a data interchange standard demands languages for data querying and transformation. Since the mid 90es, several such languages have been proposed that are inspired from functional languages (such as XSLT [1]) and/or database query languages (such as XQuery [2]). This paper addresses applying logic programming concepts and techniques to designing a declarative, rule-based query and transformation language for XML and semistructured data. The paper first introduces issues specific to XML and semistructured data such as the necessity of flexible āquery termsā and of āconstruct termsā. Then, it is argued that logic programming concepts are particularly appropriate for a declarative query and transformation language for XML and semistructured data. Finally, a new form of unification, called āsimulation unificationā, is proposed for answering āquery termsā, and it is illustrated on examples
Expression of a human alpha-1,3/4-fucosyltransferase in the pit cell lineage of FVB/N mouse stomach results in production of Leb-containing glycoconjugates: a potential transgenic mouse model for studying Helicobacter pylori infection.
CELLO: A fast algorithm for Covariance Estimation
We present CELLO (Covariance Estimation and Learning through Likelihood Optimization), an algorithm for predicting the covariances of measurements based on any available informative features. This algorithm is intended to improve the accuracy and reliability of on-line state estimation by providing a principled way to extend the conventional fixed-covariance Gaussian measurement model. We show that in experiments, CELLO learns to predict measurement covariances that agree with empirical covariances obtained by manually annotating sensor regimes. We also show that using the learned covariances during filtering provides substantial quantitative improvement to the overall state estimate. Ā© 2013 IEEE.United States. National Aeronautics and Space AdministrationSiemens Corporate ResearchUnited States. Office of Naval Research. Multidisciplinary University Research InitiativeMicro Autonomous Consortium Systems and Technolog
Effets de l'exposition Ć un insecticide carbamate, le carbofuran, sur les performances de jeunes stades de brochet (Esox lucius L., 1758) : rĆ©sultats prĆ©liminaires
Fifty years of business confidence surveys on manufacturing sector
In this work the evolution of the Italian Business Confidence Survey on manufacturing sector is presented starting from the preliminary European project for harmonized statistics launched in the late fifties of the last century. Survey changes are described, focusing in particular on the so-called confidence indicator. The continuing increase of statistical accuracy in sampling is recalled, from the initial purposive sample and controls, up to the present state of the art. Specific attention is devoted to the role of administrative archives in the sampling plan. Emphasis is also given to the increasing use of computer simulation in assessing the validity of the estimates. The role of cyclical analysis is finally highlighted with regard to two aspects: (1) the business confidence has not a corresponding variable in the economic system\u2014the validation can only be performed in comparison with correlated variables (e.g. IP, GDP); (2) confidence shows forecasting capability for the economic system
Four Lessons in Versatility or How Query Languages Adapt to the Web
Exposing not only human-centered information, but machine-processable data on the Web is one of the commonalities of recent Web trends. It has enabled a new kind of applications and businesses where the data is used in ways not foreseen by the data providers. Yet this exposition has fractured the Web into islands of data, each in different Web formats: Some providers choose XML, others RDF, again others JSON or OWL, for their data, even in similar domains. This fracturing stifles innovation as application builders have to cope not only with one Web stack (e.g., XML technology) but with several ones, each of considerable complexity. With Xcerpt we have developed a rule- and pattern based query language that aims to give shield application builders from much of this complexity: In a single query language XML and RDF data can be accessed, processed, combined, and re-published. Though the need for combined access to XML and RDF data has been recognized in previous work (including the W3Cās GRDDL), our approach differs in four main aspects: (1) We provide a single language (rather than two separate or embedded languages), thus minimizing the conceptual overhead of dealing with disparate data formats. (2) Both the declarative (logic-based) and the operational semantics are unified in that they apply for querying XML and RDF in the same way. (3) We show that the resulting query language can be implemented reusing traditional database technology, if desirable. Nevertheless, we also give a unified evaluation approach based on interval labelings of graphs that is at least as fast as existing approaches for tree-shaped XML data, yet provides linear time and space querying also for many RDF graphs. We believe that Web query languages are the right tool for declarative data access in Web applications and that Xcerpt is a significant step towards a more convenient, yet highly efficient data access in a āWeb of Dataā
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