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Rapid Design and Manufacture of Ultralight Cellular Materials
This paper details the design, manufacture and testing of regular metallic lattice structures
with unit cell sizes in the range 0.8mm to 5mm and truss elements of 100-500 µm in diameter [1].
The structures were manufactured using Selective Laser Melting (SLM) technology from 316L
stainless steel. Compression tests have shown yield loadings of over 3.5kN despite being only
18mm by 18mm by 10mm in height, the results are favourably comparable to current
commercially available metallic foams. Software has been developed that creates slice files
without the use of CAD software or STL files and is capable of producing lattices within a
volume defined by a STL file.Mechanical Engineerin
Sintered aluminium heat pipe (SAHP)
This work is the product of an ongoing PhD project in the School of the Built and Natural Environment of Northumbria University in collaboration with the University of Liverpool and Thermacore Europe Ltd. The achievements at the end of the first year are summarized. The main objective of the project is to develop an aluminum ammonia heat pipe with a sintered wick structure. Currently available ammonia heat pipes mainly use extruded axially grooved aluminum tubes as a capillary wick. There have been a few attempts of employing porous steel or nickel wicks in steel tubes with ammonia as the working fluid (Bai, Lin et al. 2009)although it is a common practice in loop heat pipes but there is no report of aluminum-ammonia heat pipes porous aluminium wick structures. The main barrier is the difficulty of sintering aluminum powders to manufacture porous wicks. So far during this project promising sintered aluminum heat pipe samples have been manufactured using the Selective Laser Melting (SLM) technique with various wick characteristics. This SLM method has proven to be capable of manufacturing very complicated wick structures with different thickness, porosity, permeability and pore sizes in different regions of a heat pipe. In addition the entire heat pipe including the end cap, outer tube wall, wick and the fill tube can be generated in a single process
The C@merata Task at MediaEval 2015: Natural Language Queries on Classical Music Scores
This was the second year of the C@merata task [16,1] which relates natural language processing to music inform ation retrieval. Participants each build a system which takes as input a query and a music score and produces as output one or more ma tching passages in the score. This year, questions were mo re difficult and scores were more complex. Participants were the same as last year and once again CLAS was the best with a Beat F-Score of 0.620
The C@merata Task at MediaEval 2014: Natural Language Queries on Classical Music Scores
This paper summarises the C@merata task in which participants built systems to answer short natural language queries about classical music scores in MusicXML. The task thus combined natural language processing with music information retrieval. Five groups from four countries submitted eight runs. The best submission scored Beat Precision 0.713 and Beat Recall 0.904
Biological surrogacy in tropical seabed assemblages fails
Surrogate taxa are used widely to represent attributes of other taxa for which data are sparse or absent. Because surveying and monitoring marine biodiversity is resource intensive, our understanding and management of marine systems will need to rely on the "availability of effective surrogates. The ability of any marine taxon to adequately, represent another, however, is largely unknown because there are rarely sufficient data for multiple taxa in the same region(s). Here, we defined a taxonomic group to be a surrogate for another taxonomic group if they possessed similar assemblage patterns. We investigated effects on surrogate performance of (1) grouping species by taxon at various levels of resolution, (2) selective removal of rare species from analysis, and (3) the number of clusters used to define assemblages, using samples for 11 phyla distributed across 1189 sites sampled from the seabed of Australia's Great Barrier Reef. This spatially and taxonomically comprehensive data set provided an opportunity for extensive testing of surrogate performance in a tropical marine system using these three approaches. for the first time, as resource and data constraints were previously limiting. We measured surrogate performance as to how similarly sampling sites were divided into assemblages between taxa. For each taxonomic group independently, we grouped sites into assemblages using. He linger distances and medoid clustering. We then used a similarity index to quantify the concordance of assemblages between all pairs Of taxonomic groups. Surrogates performed better when taxa were grouped at a phylum level, compared to taxa grouped at a finer taxonomic resolution, and were unaffected by the exclusion of spatially rare species. Mean surrogate performance increased as the number of clusters decreased. Moreover, no taxonomic group was a particularly good surrogate for any other, suggesting that the use of any one (or few) group(s) for mapping seabed biodiversity patterns is imprudent; sampling several taxonomic groups appears to be essential for understanding tropical/subtropical seabed communities. Consequently, where resource constraints do not allow complete surveying of biodiversity, it may be preferable to exclude rare species to allow investment in a broader range of taxonomic groups
ENIGMA: Efficient Learning-based Inference Guiding Machine
ENIGMA is a learning-based method for guiding given clause selection in
saturation-based theorem provers. Clauses from many proof searches are
classified as positive and negative based on their participation in the proofs.
An efficient classification model is trained on this data, using fast
feature-based characterization of the clauses . The learned model is then
tightly linked with the core prover and used as a basis of a new parameterized
evaluation heuristic that provides fast ranking of all generated clauses. The
approach is evaluated on the E prover and the CASC 2016 AIM benchmark, showing
a large increase of E's performance.Comment: Submitted to LPAR 201
First-Order Logic Theorem Proving and Model Building via Approximation and Instantiation
In this paper we consider first-order logic theorem proving and model
building via approximation and instantiation. Given a clause set we propose its
approximation into a simplified clause set where satisfiability is decidable.
The approximation extends the signature and preserves unsatisfiability: if the
simplified clause set is satisfiable in some model, so is the original clause
set in the same model interpreted in the original signature. A refutation
generated by a decision procedure on the simplified clause set can then either
be lifted to a refutation in the original clause set, or it guides a refinement
excluding the previously found unliftable refutation. This way the approach is
refutationally complete. We do not step-wise lift refutations but conflicting
cores, finite unsatisfiable clause sets representing at least one refutation.
The approach is dual to many existing approaches in the literature because our
approximation preserves unsatisfiability
Inversion symmetric 3-monopoles and the Atiyah-Hitchin manifold
We consider 3-monopoles symmetric under inversion symmetry. We show that the
moduli space of these monopoles is an Atiyah-Hitchin submanifold of the
3-monopole moduli space. This allows what is known about 2-monopole dynamics to
be translated into results about the dynamics of 3-monopoles. Using a numerical
ADHMN construction we compute the monopole energy density at various points on
two interesting geodesics. The first is a geodesic over the two-dimensional
rounded cone submanifold corresponding to right angle scattering and the second
is a closed geodesic for three orbiting monopoles.Comment: latex, 22 pages, 2 figures. To appear in Nonlinearit
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