10,148 research outputs found
Complex permeability of soft magnetic ferrite polyester resin composites at frequencies above 1 MHz
Composite soft magnetic materials consist of magnetic particles in a non-magnetic matrix. The properties of such materials can be modelled using effective medium theory. Measurements have been made of the complex permeability of composites produced using ferrite powder and polyester resin. The success of various effective medium expressions in predicting the variation of complex permeability with composition has been assessed
Proofs for free - parametricity for dependent types
Reynolds' abstraction theorem shows how a typing judgement in System F can be translated into a relational statement (in second order predicate logic) about inhabitants of the type. We obtain a similar result for pure type systems: for any PTS used as a programming language, there is a PTS that can be used as a logic for parametricity. Types in the source PTS are translated to relations (expressed as types) in the target. Similarly, values of a given type are translated to proofs that the values satisfy the relational interpretation. We extend the result to inductive families. We also show that the assumption that every term satisfies the parametricity condition generated by its type is consistent with the generated logic
Turbofan forced mixer lobe flow modeling. 1: Experimental and analytical assessment
A joint analytical and experimental investigation of three-dimensional flowfield development within the lobe region of turbofan forced mixer nozzles is described. The objective was to develop a method for predicting the lobe exit flowfield. In the analytical approach, a linearized inviscid aerodynamical theory was used for representing the axial and secondary flows within the three-dimensional convoluted mixer lobes and three-dimensional boundary layer analysis was applied thereafter to account for viscous effects. The experimental phase of the program employed three planar mixer lobe models having different waveform shapes and lobe heights for which detailed measurements were made of the three-dimensional velocity field and total pressure field at the lobe exit plane. Velocity data was obtained using Laser Doppler Velocimetry (LDV) and total pressure probing and hot wire anemometry were employed to define exit plane total pressure and boundary layer development. Comparison of data and analysis was performed to assess analytical model prediction accuracy. As a result of this study a planar mixed geometry analysis was developed. A principal conclusion is that the global mixer lobe flowfield is inviscid and can be predicted from an inviscid analysis and Kutta condition
HTC Scientific Computing in a Distributed Cloud Environment
This paper describes the use of a distributed cloud computing system for
high-throughput computing (HTC) scientific applications. The distributed cloud
computing system is composed of a number of separate
Infrastructure-as-a-Service (IaaS) clouds that are utilized in a unified
infrastructure. The distributed cloud has been in production-quality operation
for two years with approximately 500,000 completed jobs where a typical
workload has 500 simultaneous embarrassingly-parallel jobs that run for
approximately 12 hours. We review the design and implementation of the system
which is based on pre-existing components and a number of custom components. We
discuss the operation of the system, and describe our plans for the expansion
to more sites and increased computing capacity
On differential uniformity of maps that may hide an algebraic trapdoor
We investigate some differential properties for permutations in the affine
group, of a vector space V over the binary field, with respect to a new group
operation , inducing an alternative vector space structure on .Comment: arXiv admin note: text overlap with arXiv:1411.768
Geometry of Non-Hausdorff Spaces and Its Significance for Physics
Hausdorff relation, topologically identifying points in a given space,
belongs to elementary tools of modern mathematics. We show that if subtle
enough mathematical methods are used to analyze this relation, the conclusions
may be far-reaching and illuminating. Examples of situations in which the
Hausdorff relation is of the total type, i.e., when it identifies all points of
the considered space, are the space of Penrose tilings and space-times of some
cosmological models with strong curvature singularities. With every Hausdorff
relation a groupoid can be associated, and a convolutive algebra defined on it
allows one to analyze the space that otherwise would remain intractable. The
regular representation of this algebra in a bundle of Hilbert spaces leads to a
von Neumann algebra of random operators. In this way, a probabilistic
description (in a generalized sense) naturally takes over when the concept of
point looses its meaning. In this situation counterparts of the position and
momentum operators can be defined, and they satisfy a commutation relation
which, in the suitable limiting case, reproduces the Heisenberg indeterminacy
relation. It should be emphasized that this is neither an additional assumption
nor an effect of a quantization process, but simply the consequence of a purely
geometric analysis.Comment: 13 LaTex pages, no figure
Temporary brittle bone disease: relationship between clinical findings and judicial outcome
There is a wide differential diagnosis for the child with unexplained fractures including non-accidental injury, osteogenesis imperfecta and vitamin D deficiency rickets. Over the last 20 years we and others have described a self-limiting syndrome characterised by fractures in the first year of life. This has been given the provisional name temporary brittle bone disease. This work had proved controversial mostly because the fractures, including rib fractures and metaphyseal fractures, were those previously regarded as typical or even diagnostic of non-accidental injury. Some have asserted that the condition does not exist. Over the years 1985 to 2000 we investigated 87 such cases with fractures with a view to determining the future care of the children. In 85 of these the judiciary was involved. We examined the clinical and radiological findings in the 33 cases in which there was a judicial finding of abuse, the 24 cases in which the parents were exonerated and the 28 cases in which no formal judicial finding was made. The three groups of patients were similar in terms of demographics, age at fracturing and details of the fractures. The clinical similarities between the three groups of patients contrast with the very different results of the judicial process
Zearalenone production and growth in drinking water inoculated with Fusarium graminearum
Production of the mycotoxin zearalenone (ZEN) was examined in drinking water inoculated with Fusarium graminearum. The strain employed was isolated from a US water distribution system. ZEN was purified with an immunoaffinity column and quantified by high-performance liquid chromatography (HPLC) with fluorescence detection. The extracellular yield of ZEN was 15.0 ng l−1. Visual growth was observed. Ergosterol was also indicative of growth and an average of 6.2 μg l−1 was obtained. Other compounds were also detected although remain unidentified. There is no equivalent information available. More work is required on metabolite expression in water as mycotoxins have consequences for human and animal health. The levels detected in this study were low. Water needs to be accepted as a potential source as it attracts high quality demands in terms of purity.Fundação para a Ciência e a Tecnologia (FCT
Survey and significance of filamentous fungi from tap water
Fungi in drinking water are involved in the production of tastes and odours in water. Health problems are possible,
originating from mycotoxins, animal pathogens and allergies. This report concerns the surveillance of mesophilic fungi
in tap water and assessment of their potential for causing problems. The methods for the determination of the
filamentous fungi (ff) were filtering, swabbing and baiting. Tap water, half-strength corn meal, neopeptone–glucose
rose Bengal aureomycin (NGRBA) and oomycete selective agars for the enumeration of colony forming units (cfu)
were used. Samples were taken consecutively over 16 months. Filtration and NGRBA gave the highest ff counts. A
total of 340 taxa were isolated. There appeared to be a negative correlation between bacterial and yeast (b/y) and ff
counts. Highest counts were found in winter months for ff and in the warmer months for b/y. Penicillium (40.6%) and
Acremonium (38.8%) were the most frequently isolated ff. There was a difference in the pattern of isolation of the key
taxa with season: penicillia predominated in early summer and Acremonium in winter. P. expansum was isolated in high
numbers in May 2004. This species is associated with the production of the mycotoxin patulin and the odour secondary
metabolite geosmin. P. brevicompactum was detected throughout the sampling period and is known to produce the
immunosuppressive drug mycophenolic acid. Acremonium is associated with ocentol production which is responsible
for bad tastes and flavours. The remaining taxa were Phialophora sp. (4.1%), Cladosporium sp. (3.5%), Rhizopus
stolonifer (2.9%), Chaetomium sp. (0.6%), Alternaria sp. (0.3%), Aspergillus sp. (0.3%), mycelia sterilia (2.6%) and
unidentified (6.2%). It is emphasised that few Aspergillus and no Fusarium strains were isolated. Rhizopus stolonifer
was obtained. However, none of the fungi isolated at mesophilic temperature used could be described as being involved
with pathogenicity per se.Fundação para a Ciência e a Tecnologia (FCT) - grant FRH/BPD/14923/2004.European Union (EU) - Fifth Framework Programme ‘‘Energy,
environment and sustainable development programme’’
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