White Rose Research Online
(13.407 recursos)
Este es el repositorio institucional de tres universidades del Reino Unido (York, Leeds y Sheffield), creado con el apoyo de SHERPA. Proporciona acceso a los artículos de investigación de las instituciones.
2.
Solving transportation bi-level programs with differential
evolution - Koh, Andrew
Bi-level programming problems arise in situations
when the decision maker has to take into account the responses
of the users to his decisions. These problems are recognized as
one of the most difficult and challenging problems in
transportation systems management. Several problems within
the transportation literature can be cast in the bi-level
programming framework. At the same time, significant
advances have been made in the deployment of stochastic
heuristics for function optimization. This paper reports on the
use of Differential Evolution (DE) for solving bi-level
programming problems with applications in the field of
transportation planning. After illustrating our solution
algorithm with some mathematical functions, we then apply
this method to two control problems...
3.
Topological correction of hypertextured implicit surfaces for ray casting - Gamito, M.N.; Maddock, S.C.
Hypertextures are a useful modelling tool in that they
can add three-dimensional detail to the surface of otherwise
smooth objects. Hypertextures can be rendered as implicit
surfaces, resulting in objects with a complex but well
defined boundary. However, representing a hypertexture as
an implicit surface often results in many small parts being
detached from the main surface, turning an object into a
disconnected set. Depending on the context, this can detract
from the realism in a scene where one usually does not
expect a solid object to have clouds of smaller objects floating around it. We present a topology correction technique, integrated in a ray casting algorithm for hypertextured...
4.
Ventilation of small livestock trailers - Gilkeson, C.A.; Wilson, M.C.T.; Thompson, H.M.; Gaskell, P.H.; Barnard, R.H.; Hackett, K.C.; Stewart, D.H.
A large number of livestock is transported to market in small box trailers. The welfare
of animals transported in this way is now assuming greater importance with the onset
of tougher EU legislation. This paper presents the first study into the ventilation of
small livestock trailers using experimental and computational methods. Wind tunnel
studies, using a 1/7th scale model, highlight the important influence of the towing
vehicle and trailer design on the airflow within the trailer. Detailed CFD analysis
agrees well with the wind tunnel data and offers the ability to assess the impact of
design changes.
5.
AutoTopography: What Can Physical Mementos Tell us about Digital Memories? - Petrelli, Daniela; Whittaker, Steve; Brockmeier, Jens
Current technology makes it possible to capture huge
amounts of information related to everyday experiences.
Despite this, we know little about the processes by which
people identify and manage mementos - objects which are
directly meaningful to their memories. Among the millions
of objects people encounter in a lifetime, few become such
reminders of people, places or events. We report fieldwork
where participants gave us a tour of their homes describing
how and why particular objects become mementos. Our
findings extend the existing digital memory literature; first our participants didnt view their activities as experiential capture, nor were mementos limited...
6.
User-system cooperation in document annotation based on information extraction - Ciravegna, F.; Dingli, A.; Petrelli, D.; Wilks, Y.
The process of document annotation for the Semantic Web is
complex and time consuming, as it requires a great deal of manual annotation. Information extraction from texts (IE) is a technology used by some very recent systems for reducing the burden of annotation. The integration of IE systems in annotation tools is quite a new development and there is still the necessity of thinking the impact of the IE system on the whole annotation process. In this
paper we initially discuss a number of requirements for the use of IE as support for annotation. Then we present and discuss a model of...
7.
Stability analysis of electric power systems for more
electric aircraft - Griffo, Antonio; Wang, J.B.; Howe, D.
This paper presents a comprehensive assessment of small-signal stability for a more-electric
aircraft power system consisting of a synchronous variable-frequency generator which supplies several power
electronic controlled loads via an 18-pulse autotransformer rectifier unit (ATRU) for AC-DC conversion.
Functional models for key power system components and loads are derived. Numerical tools employed for the
automatic calculation of linearized equations and operating points are described, and the influence of leading
design and operational parameter on system stability is evaluated.
8.
State-space average modelling of 18-pulse diode rectifier - Griffo, Antonio; Wang, J.B.; Howe, D.
The paper presents an averaged-value model of the direct symmetric topology of 18-pulse
autotransformer AC-DC rectifiers. The model captures the key features of the dynamic characteristics of the
rectifiers, while being time invariant and computationally efficient. The developed models, validated by
comparison of the resultant transient and steady state behaviours with those obtained from detailed simulations
can, therefore, be used for stability assessment of electric power systems with diode rectifiers, multiple power
electronic converter-controlled loads and electrical drives.
9.
Initial Observations on Query Based Sampling in Distributed CLIR - Shou, X.M.; Sanderson, M.
Cross Language Information Retrieval (CLIR) enables people to search information written in different languages from their query languages. Information can be retrieved either from a single cross lingual collection or from a variety of dis-tributed cross lingual sources. This paper pre-sents initial results exploring the effectiveness of distributed CLIR using query-based sampling techniques, which to the best of our knowledge has not been investigated before. In distributed retrieval with multiple databases, query-based sampling provides a simple and effective way for acquiring accurate resource descriptions which helps to select which databases to search. Obser-vations from our initial experiments show that the...
10.
Information retrieval system evaluation: effort, sensitivity, and reliability - Sanderson, M.; Zobel, J.
The effectiveness of information retrieval systems is measured by
comparing performance on a common set of queries and
documents. Significance tests are often used to evaluate the
reliability of such comparisons. Previous work has examined
such tests, but produced results with limited application. Other
work established an alternative benchmark for significance, but
the resulting test was too stringent. In this paper, we revisit the
question of how such tests should be used. We find that the t-test
is highly reliable (more so than the sign or Wilcoxon test), and is
far more reliable than simply showing a large percentage
difference in effectiveness measures between IR systems. Our
results show that past...
11.
Experiments on data fusion using headline information - Shou, X.M.; Sanderson, M.
This poster describes initial work exploring a relatively unexamined area of data fusion: fusing the results of retrieval
systems whose collections have no overlap between them. Many of the effective meta-search/data fusion strategies
gain much of their success from exploiting document overlap across the source systems being merged. When the
intersection of the collections is the empty set, the strategies generally degrade to a simpler form. In order to address
such situations, two strategies were examined: re-ranking of merged results using a locally run search on the text
fragments returned by the source search engines; and re-ranking based on cross document similarity, again using text
fragments...
12.
A Binary Neural Shape Matcher using Johnson Counters and Chain Codes - Hodge, Victoria; O'Keefe, Simon; Austin, Jim
In this paper, we introduce a neural network-based shape
matching algorithm that uses Johnson Counter codes coupled
with chain codes. Shape matching is a fundamental
requirement in content-based image retrieval systems. Chain
codes describe shapes using sequences of numbers. They are
simple and flexible. We couple this power with the efficiency and flexibility of a binary associative-memory neural network. We focus on the implementation details of the algorithm when it is constructed using the neural network. We demonstrate how the binary associative-memory neural network can index and match chain codes where the chain code elements are represented by Johnson codes.
13.
Deriving concept hierarchies from text - Sanderson, M.; Croft, B.
This paper presents a means of automatically deriving a
hierarchical organization of concepts from a set of documents
without use of training data or standard clustering techniques.
Instead, salient words and phrases extracted from the documents
are organized hierarchically using a type of co-occurrence known
as subsumption. The resulting structure is displayed as a series
of hierarchical menus. When generated from a set of retrieved
documents, a user browsing the menus is provided with a
detailed overview of their content in a manner distinct from
existing overview and summarization techniques. The methods
used to build the structure are simple, but appear to be effective:
a small-scale user study reveals that the...
14.
Search words and geography - Sanderson, M.; Han, Y.
In this paper, we present a preliminary study of geographic query
words, which users tend to re-use. The categories of the words
demonstrate that geographically related words take up the largest
proportion of all repeated words. These geo-words refer to a range
of spatial areas. In addition, it was found that different geo-word
types are re-used in different ways by users.
15.
Forming test collections with no system pooling - Sanderson, M.; Joho, H.
Forming test collection relevance judgments from the pooled
output of multiple retrieval systems has become the standard
process for creating resources such as the TREC, CLEF, and
NTCIR test collections. This paper presents a series of
experiments examining three different ways of building test
collections where no system pooling is used. First, a collection
formation technique combining manual feedback and multiple
systems is adapted to work with a single retrieval system. Second,
an existing method based on pooling the output of multiple
manual searches is re-examined: testing a wider range of
searchers and retrieval systems than has been examined before.
Third, a new approach is explored where the ranked output of...
16.
Analyzing geographic queries - Sanderson, M.; Kohler, J.
The aim of this study was to analyze the 2001 Excite query log to
investigate the extent and variation of Web queries containing
geographic terms. In particular, an investigation into what people
search for when they use geographic terms, the ways in which
they describe a geographic location, the terminology used to find
geographically related information and the structure of users
queries when looking for geographically related information on
the Web. This study also attempted to determine how
geographically related queries differ from other queries.
Geographically related queries formed nearly one fifth of all
queries submitted to Excite, the terms occurring most frequently
being place names. Geographic queries were also shown...
17.
Problems with Kendall's Tau - Sanderson, M.; Soboroff, I.
This poster describes a potential problem with a relatively well used measure in Information Retrieval research: Kendall's Tau rank correlation coefficient. The coefficient is best known for its use in determining the similarity of test collections when ranking sets of retrieval runs. Threshold values for the coefficient have been defined and used in a number of published studies in information retrieval. However, this poster presents results showing that basing decisions on such thresholds is not as reliableas has been assumed.
19.
Ambiguous queries: test collections need more sense - Sanderson, M.
Although there are many papers examining ambiguity in
Information Retrieval, this paper shows that there is a whole class
of ambiguous word that past research has barely explored. It is
shown that the class is more ambiguous than other word types and
is commonly used in queries. The lack of test collections
containing ambiguous queries is highlighted and a method for
creating collections from existing resources is described. Tests
using the new collection show the impact of query ambiguity on
an IR system: it is shown that conventional systems are incapable
of dealing effectively with such queries and that current
assumptions about how to improve search effectiveness do not
hold when...
20.
Measuring pseudo relevance feedback & CLIR - Sanderson, M.; Clough, P.
In this poster, we report on the effects of pseudo relevance
feedback (PRF) for a cross language image retrieval task using a
test collection. Typically PRF has been shown to improve
retrieval performance in previous CLIR experiments based on
average precision at a fixed rank. However our experiments have
shown that queries in which no relevant documents are returned
also increases. Because query reformulation for cross language is
likely to be harder than with monolingual searching, a great deal
of user dissatisfaction would be associated with this scenario. We
propose that an additional effectiveness measure based on failed
queries may better reflect user satisfaction than average precision
alone.
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