3,723 research outputs found
Computer program for compressible flow network analysis
Program solves problem of an arbitrarily connected one dimensional compressible flow network with pumping in the channels and momentum balancing at flow junctions. Program includes pressure drop calculations for impingement flow and flow through pin fin arrangements, as currently found in many air cooled turbine bucket and vane cooling configurations
Performance evaluation of the Boron Coated Straws detector with Geant4
The last decade has witnessed the development of several alternative neutron
detector technologies, as a consequence of upcoming neutron sources and
upgrades, as well the world-wide shortage of He. One branch of development
is the family of B-based gaseous detectors. This work focuses on the
boron coated straws (BCS) by Proportional Technologies Inc., a commercial
solution designed for use in homeland security and neutron science. A detailed
Geant4 simulation study of the BCS is presented, which investigates various
aspects of the detector performance, e.g. efficiency, activation, absorption
and the impact of scattering on the measured signal. The suitability of the BCS
detector for Small Angle Neutron Scattering (SANS), direct chopper spectrometry
and imaging is discussed.Comment: 50 pages, 37 figures, minor changes after review, results unchange
Variable-camber systems integration and operational performance of the AFTI/F-111 mission adaptive wing
The advanced fighter technology integration, the AFTI/F-111 aircraft, is a preproduction F-111A testbed research airplane that was fitted with a smooth variable-camber mission adaptive wing. The camber was positioned and controlled by flexing the upper skins through rotary actuators and linkages driven by power drive units. The wing camber and control system are described. The measured servoactuator frequency responses are presented along with analytical predictions derived from the integrated characteristics of the control elements. A mission adaptive wing system chronology is used to illustrate and assess the reliability and dependability of the servoactuator system during 1524 hours of ground tests and 145 hours of flight testing
Pro-p subgroups of profinite completions of 3-manifold groups
We completely describe the finitely generated pro- subgroups of the profinite completion of the fundamental group of an arbitrary 3-manifold. We also prove a pro- analogue of the main theorem of Bass–Serre theory for finitely generated pro- groups.The first author was supported by EPSRC Standard Grant (number EP/L026481/1). The second author was supported by CAPES as part of the ‘Est´agio Senior’ programme
Suppression of intrinsic neutron background in the Multi-Grid detector
One of the key requirements for neutron scattering instruments is the
Signal-to-Background ratio (SBR). This is as well a design driving requirement
for many instruments at the European Spallation Source (ESS), which aspires to
be the brightest neutron source of the world. The SBR can be effectively
improved with background reduction. The Multi-Grid, a large-area thermal
neutron detector with a solid boron carbide converter, is a novel solution for
chopper spectrometers. This detector will be installed for the three
prospective chopper spectrometers at the ESS. As the Multi-Grid detector is a
large area detector with a complex structure, its intrinsic background and its
suppression via advanced shielding design should be investigated in its
complexity, as it cannot be naively calculated. The intrinsic scattered neutron
background and its effect on the SBR is determined via a detailed Monte Carlo
simulation for the Multi-Grid detector module, designed for the CSPEC
instrument at the ESS. The impact of the detector vessel and the neutron
entrance window on scattering is determined, revealing the importance of an
optimised internal detector shielding. The background-reducing capacity of
common shielding geometries, like side-shielding and end-shielding is
determined by using perfect absorber as shielding material, and common
shielding materials, like BC and Cd are also tested. On the basis of the
comparison of the effectiveness of the different shielding topologies and
materials, recommendations are given for a combined shielding of the Multi-Grid
detector module, optimised for increased SBR.Comment: 26 pages, 18 figures, revise
T-RECX: Tiny-Resource Efficient Convolutional neural networks with early-eXit
Deploying Machine learning (ML) on milliwatt-scale edge devices (tinyML) is
gaining popularity due to recent breakthroughs in ML and Internet of Things
(IoT). Most tinyML research focuses on model compression techniques that trade
accuracy (and model capacity) for compact models to fit into the KB-sized
tiny-edge devices. In this paper, we show how such models can be enhanced by
the addition of an early exit intermediate classifier. If the intermediate
classifier exhibits sufficient confidence in its prediction, the network exits
early thereby, resulting in considerable savings in time. Although early exit
classifiers have been proposed in previous work, these previous proposals focus
on large networks, making their techniques suboptimal/impractical for tinyML
applications. Our technique is optimized specifically for tiny-CNN sized
models. In addition, we present a method to alleviate the effect of network
overthinking by leveraging the representations learned by the early exit. We
evaluate T-RecX on three CNNs from the MLPerf tiny benchmark suite for image
classification, keyword spotting and visual wake word detection tasks. Our
results show that T-RecX 1) improves the accuracy of baseline network, 2)
achieves 31.58% average reduction in FLOPS in exchange for one percent accuracy
across all evaluated models. Furthermore, we show that our methods consistently
outperform popular prior works on the tiny-CNNs we evaluate.Comment: Accepted at 20th ACM International Conference on Computing Frontier
Scaffold searching: automated identification of similar ring systems for the design of combinatorial libraries
Rigid ring systems can be used to position receptor-binding functional groups in 3D space and they thus play an increasingly important role in the design of combinatorial libraries. This paper discusses the use of shape-similarity methods to identify ring systems that are structurally similar to, and aligned with, a user-defined target ring system. These systems can be used as alternative scaffolds for the construction of a combinatorial library
Ecological significance of deep-layer sloughing in the eulittoral zone coralline alga, Spongites yendoi (Foslie) Chamberlain (Corallinaceae, Rhodophyta) in South Africa.
The crustose coralline alga Spongites yendoi (Foslie) Chamberlain (Corallinaceae, Rhodophyta) dominates the lower eulittoral zone along the South Coast of South Africa, together with the limpet Patella cochlear Born. This coralline alga was previously shown to undergo a deep-layer sloughing twice a year, as well as continuous epithallial sloughing. The hypothesis that deep-layer sloughing could perform an antifouling function was tested by determining the percentage cover of fleshy algae developing in a limpet exclusion experiment on live and killed coralline. Substantial fleshy algal cover developed in both limpet removal treatments, negating any possible antifouling function of deep-layer sloughing. A measurable decrease in the mean thickness of the coralline population was noted during periods of sloughing. A thicker crustose coralline, Leptophytum ferox (Foslie) Chamberlain & Keats, grew more slowly and was much more heavily burrowed and more weakly attached than S. yendoi. These results are consistent with a hypothesis that deep-layer sloughing contributes to the alga's relatively thin thallus, thereby conferring the advantages of faster growth and stronger attachment. However, further studies are still needed to evaluate these hypotheses further.Web of Scienc
Soft-tissue specimen shrinkage during the preparation for scanning electron microscopy
KIMThe amount of shrinkage and the scanning electron microscope appearance of specimens of rat tongue, soft palate and small intestine, dehydrated by air drying , the critical point technique, the camphene technique and freeze drying were compare
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