1,206,067 research outputs found
On the Identification of the Costs of Simultaneous Search
This paper studies the identification of the costs of simultaneous search in a class of (portfolio) problems studied by Chade and Smith (2006). We show that aggregate data from a single market, or disaggregate data from a single market segment, do not provide sufficient information to identify the costs of simultaneous search in any reasonable interval. We then show that by pooling aggregate data from multiple markets, or disaggregate data from multiple market segments, the econometrician can identify the costs of simultaneous search in a non-empty interval. Within the context of specific examples, we illustrate that identification of the search cost distribution in its full support may easily be obtained.search costs, portfolio choice, non-parametric identification
Planning complex engineer-to-order products
The design and manufacture of complex Engineer-to-Order products is characterised by uncertain operation durations, finite capacity resources and multilevel product structures. Two scheduling methods are presented to minimise expected costs for multiple products across multiple finite capacity resources. The first sub-optimises the operations sequence, using mean operation durations, then refines the schedule by perturbation. The second method generates a schedule of start times directly by random search with an embedded simulation of candidate schedules for evaluation. The methods are compared for industrial examples
Cluster counting: The Hoshen-Kopelman algorithm vs. spanning tree approaches
Two basic approaches to the cluster counting task in the percolation and
related models are discussed. The Hoshen-Kopelman multiple labeling technique
for cluster statistics is redescribed. Modifications for random and aperiodic
lattices are sketched as well as some parallelised versions of the algorithm
are mentioned. The graph-theoretical basis for the spanning tree approaches is
given by describing the "breadth-first search" and "depth-first search"
procedures. Examples are given for extracting the elastic and geometric
"backbone" of a percolation cluster. An implementation of the "pebble game"
algorithm using a depth-first search method is also described.Comment: LaTeX, uses ijmpc1.sty(included), 18 pages, 3 figures, submitted to
Intern. J. of Modern Physics
Strategies for Searching Video Content with Text Queries or Video Examples
The large number of user-generated videos uploaded on to the Internet
everyday has led to many commercial video search engines, which mainly rely on
text metadata for search. However, metadata is often lacking for user-generated
videos, thus these videos are unsearchable by current search engines.
Therefore, content-based video retrieval (CBVR) tackles this metadata-scarcity
problem by directly analyzing the visual and audio streams of each video. CBVR
encompasses multiple research topics, including low-level feature design,
feature fusion, semantic detector training and video search/reranking. We
present novel strategies in these topics to enhance CBVR in both accuracy and
speed under different query inputs, including pure textual queries and query by
video examples. Our proposed strategies have been incorporated into our
submission for the TRECVID 2014 Multimedia Event Detection evaluation, where
our system outperformed other submissions in both text queries and video
example queries, thus demonstrating the effectiveness of our proposed
approaches
Designing and recasting LHC analyses with MadAnalysis 5
We present an extension of the expert mode of the MadAnalysis 5 program
dedicated to the design or reinterpretation of high-energy physics collider
analyses. We detail the predefined classes, functions and methods available to
the user and emphasize the most recent developments. The latter include the
possible definition of multiple sub-analyses and a novel user-friendly
treatment for the selection criteria. We illustrate this approach by two
concrete examples: a CMS search for supersymmetric partners of the top quark
and a phenomenological analysis targeting hadronically decaying monotop
systems.Comment: 17 pages, 3 figures, 10 tables; version accepted by EPJ
Time-Staging Enhancement of Hybrid System Falsification
Optimization-based falsification employs stochastic optimization algorithms
to search for error input of hybrid systems. In this paper we introduce a
simple idea to enhance falsification, namely time staging, that allows the
time-causal structure of time-dependent signals to be exploited by the
optimizers. Time staging consists of running a falsification solver multiple
times, from one interval to another, incrementally constructing an input signal
candidate. Our experiments show that time staging can dramatically increase
performance in some realistic examples. We also present theoretical results
that suggest the kinds of models and specifications for which time staging is
likely to be effective
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