5,111 research outputs found
Classification of Generalized Multiresolution Analyses
We discuss how generalized multiresolution analyses (GMRAs), both classical
and those defined on abstract Hilbert spaces, can be classified by their
multiplicity functions and matrix-valued filter functions . Given a
natural number valued function and a system of functions encoded in a
matrix satisfying certain conditions, a construction procedure is described
that produces an abstract GMRA with multiplicity function and filter
system . An equivalence relation on GMRAs is defined and described in terms
of their associated pairs . This classification system is applied to
classical examples in as well as to previously studied
abstract examples.Comment: 18 pages including bibliograp
Thin film dielectric microstrip kinetic inductance detectors
Microwave Kinetic Inductance Detectors, or MKIDs, are a type of low
temperature detector that exhibit intrinsic frequency domain multiplexing at
microwave frequencies. We present the first theory and measurements on a MKID
based on a microstrip transmission line resonator. A complete characterization
of the dielectric loss and noise properties of these resonators is performed,
and agrees well with the derived theory. A competitive noise equivalent power
of 5 W Hz at 1 Hz has been demonstrated. The
resonators exhibit the highest quality factors known in a microstrip resonator
with a deposited thin film dielectric.Comment: 10 pages, 4 figures, APL accepte
An inquiry-based learning approach to teaching information retrieval
The study of information retrieval (IR) has increased in interest and importance with the explosive growth of online information in recent years. Learning about IR within formal courses of study enables users of search engines to use
them more knowledgeably and effectively, while providing the starting point for the explorations of new researchers into novel search technologies. Although IR can be taught in a traditional manner of formal classroom instruction with students being led through the details of the subject and expected to reproduce this in assessment, the nature of IR as a topic makes it an ideal subject for inquiry-based learning approaches to teaching. In an inquiry-based learning approach students are introduced to the principles of a subject and then encouraged to develop their understanding by solving structured or open problems. Working through solutions in subsequent class discussions enables students to appreciate the availability of alternative solutions as proposed by their classmates. Following this approach students not only learn the details of IR techniques, but significantly, naturally learn to apply them in solution of problems. In doing this they not only gain an appreciation of alternative solutions to a problem, but also how to assess their relative strengths and weaknesses. Developing confidence and skills in problem solving enables student assessment to be structured around solution of problems. Thus students can be assessed on the basis of their understanding and ability to apply techniques, rather simply their skill at reciting facts. This has the additional benefit of encouraging general problem solving skills which can be of benefit in other subjects. This approach to teaching IR was successfully implemented in an undergraduate module where students were
assessed in a written examination exploring their knowledge and understanding of the principles of IR and their ability to apply them to solving problems, and a written assignment based on developing an individual research proposal
Dichotomizing partial compliance and increased participant burden in factorial designs: the performance of four noncompliance methods
A Memory Bandwidth-Efficient Hybrid Radix Sort on GPUs
Sorting is at the core of many database operations, such as index creation,
sort-merge joins, and user-requested output sorting. As GPUs are emerging as a
promising platform to accelerate various operations, sorting on GPUs becomes a
viable endeavour. Over the past few years, several improvements have been
proposed for sorting on GPUs, leading to the first radix sort implementations
that achieve a sorting rate of over one billion 32-bit keys per second. Yet,
state-of-the-art approaches are heavily memory bandwidth-bound, as they require
substantially more memory transfers than their CPU-based counterparts.
Our work proposes a novel approach that almost halves the amount of memory
transfers and, therefore, considerably lifts the memory bandwidth limitation.
Being able to sort two gigabytes of eight-byte records in as little as 50
milliseconds, our approach achieves a 2.32-fold improvement over the
state-of-the-art GPU-based radix sort for uniform distributions, sustaining a
minimum speed-up of no less than a factor of 1.66 for skewed distributions.
To address inputs that either do not reside on the GPU or exceed the
available device memory, we build on our efficient GPU sorting approach with a
pipelined heterogeneous sorting algorithm that mitigates the overhead
associated with PCIe data transfers. Comparing the end-to-end sorting
performance to the state-of-the-art CPU-based radix sort running 16 threads,
our heterogeneous approach achieves a 2.06-fold and a 1.53-fold improvement for
sorting 64 GB key-value pairs with a skewed and a uniform distribution,
respectively.Comment: 16 pages, accepted at SIGMOD 201
On Functions That Are Trivial Cocycles for a Set of Irrationals. II
Two results are obtained about the topological size of the set of irrationals for which a given function is a trivial cocycle. An example of a continuous function which is a coboundary with non-L(1) cobounding function is constructed
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