766 research outputs found
Control of heat transfer in engine coolers by Lorentz forces
Abstract In engine coolers of off-highway vehicles convective heat transfer at the coolant side is a limiting factor of both efficiency and performance density of the cooler. Here, due to design restrictions, backwater areas and stagnation regions appear that are caused by flow deflections and cross-sectional expansions. As appropriate coolants, mixtures of water and glysantine are commonly used. Such coolants are characterized by their electrical conductivity of some S/m. This gives rise to control coolant flow and therefore convective heat transfer by means of Lorentz forces. These body forces are generated within the weakly conducting fluid by the interactions of an electrical current density and a localized magnetic field both of which being externally superimposed. In application this may be achieved by inserting electrodes in the cooler wall and a corresponding arrangement of permanent magnets. In this paper we perform numerical simulations of such magnetohydrodynamic flow in three model geometries that are frequently apparent in engine cooling applications: Carnot-Borda diffusor, 90° bend, and 180° bend. The simulations are carried out using the software package ANSYS Fluent. The present study demonstrates that, depending on the electromagnetic interaction parameter and the specific geometric arrangement of electrodes and magnetic field, Lorentz forces are suitable to break up eddy waters and separation zones and are thus significantly increasing convective heat transfer in these areas. Furthermore, the results show that due to the action of the Lorentz forces the hydraulic pressure losses can be reduced
Considerations for Research Funders and Managers to Facilitate the Translation of Scientific Knowledge into Practice
Research funders and managers can play a critical role in supporting the translation of knowledge into action by facilitating the brokering of knowledge and partnerships. We use semi-structured interviews with a research funding agency, the Australian Centre for International Agricultural Research (ACIAR), to explore (i) ways that funders can facilitate knowledge brokering, the (ii) barriers to, and (iii) enablers for, facilitating knowledge brokering, and (iv) the individual skills and attributes for research program funders and managers to be effective brokers. Based on these findings, we generate three considerations for research funders elsewhere, in particular R4D funders, seeking to build capacity for knowledge brokering: (i) formalise the process and practice, (ii) develop shared language and understanding, and (iii) build individual competencies and capabilities. Our findings complement the existing literature with a context specific analysis of how research funders can facilitate knowledge brokering, and by identifying the barriers and enablers in doing so
Second-line cabozantinib versus nivolumab in advanced renal cell carcinoma: Systematic review and indirect treatment comparison
Background: Nivolumab and cabozantinib, two new treatment options for previously-treated advanced/metastatic renal cell carcinoma (aRCC), have recently been approved. Methods: Two independent reviewers performed study selection, data extraction, and risk of bias assessment. Indirect treatment comparisons were carried out by directly assessing HR differences and statistical modeling of Kaplan-Meier curves from these two trials. Results: Publications identified showed that no head-to-head comparisons had been carried out. Two indirect treatment comparisons used agreed that there was no significant difference in OS between cabozantinib and nivolumab and that cabozantinib significantly improved PFS compared to nivolumab. Conclusions: The field of aRCC treatments is evolving rapidly, creating opportunities for individualized treatments and challenges for clinicians to keep up with the evidence. In lieu of availability of direct comparisons of all options, advanced modeling results presented herein can help to inform and improve personalized treatments
A Tonnetz Model for pentachords
This article deals with the construction of surfaces that are suitable for
representing pentachords or 5-pitch segments that are in the same class.
It is a generalization of the well known \"Ottingen-Riemann torus for triads of
neo-Riemannian theories. Two pentachords are near if they differ by a
particular set of contextual inversions and the whole contextual group of
inversions produces a Tiling (Tessellation) by pentagons on the surfaces. A
description of the surfaces as coverings of a particular Tiling is given in the
twelve-tone enharmonic scale case.Comment: 27 pages, 12 figure
ProtoDESI: First On-Sky Technology Demonstration for the Dark Energy Spectroscopic Instrument
The Dark Energy Spectroscopic Instrument (DESI) is under construction to
measure the expansion history of the universe using the baryon acoustic
oscillations technique. The spectra of 35 million galaxies and quasars over
14,000 square degrees will be measured during a 5-year survey. A new prime
focus corrector for the Mayall telescope at Kitt Peak National Observatory will
deliver light to 5,000 individually targeted fiber-fed robotic positioners. The
fibers in turn feed ten broadband multi-object spectrographs. We describe the
ProtoDESI experiment, that was installed and commissioned on the 4-m Mayall
telescope from August 14 to September 30, 2016. ProtoDESI was an on-sky
technology demonstration with the goal to reduce technical risks associated
with aligning optical fibers with targets using robotic fiber positioners and
maintaining the stability required to operate DESI. The ProtoDESI prime focus
instrument, consisting of three fiber positioners, illuminated fiducials, and a
guide camera, was installed behind the existing Mosaic corrector on the Mayall
telescope. A Fiber View Camera was mounted in the Cassegrain cage of the
telescope and provided feedback metrology for positioning the fibers. ProtoDESI
also provided a platform for early integration of hardware with the DESI
Instrument Control System that controls the subsystems, provides communication
with the Telescope Control System, and collects instrument telemetry data.
Lacking a spectrograph, ProtoDESI monitored the output of the fibers using a
Fiber Photometry Camera mounted on the prime focus instrument. ProtoDESI was
successful in acquiring targets with the robotically positioned fibers and
demonstrated that the DESI guiding requirements can be met.Comment: Accepted versio
Direct Dark Matter Search using CCDs
There is currently vast evidence for Dark Matter (DM) from astronomical
observations. However, in spite of tremendous efforts by large experimental
groups, there is no confirmed direct detection of the dark matter in our
galaxy. Recent experimental results and theoretical developments suggest the
possibility of a DM particle with mass below 10 GeV, such a particle would
escape most of the direct searches due to the large thresholds for the
detection of nuclear recoils typically used. In this work we study the
possibility of a new Dark Matter search with an unprecedented low threshold for
the detection of nuclear recoils using high-resistivity CCD detectors (hr-CCD).
Due to their extremely low readout noise and the relatively large active mass,
these detectors present a unique opportunity in this field.Comment: paper presented at the Taup2009 Conferenc
Quality control in resting-state fMRI: the benefits of visual inspection
Background: A variety of quality control (QC) approaches are employed in resting-state functional magnetic resonance imaging (rs-fMRI) to determine data quality and ultimately inclusion or exclusion of a fMRI data set in group analysis. Reliability of rs-fMRI data can be improved by censoring or “scrubbing” volumes affected by motion. While censoring preserves the integrity of participant-level data, including excessively censored data sets in group analyses may add noise. Quantitative motion-related metrics are frequently reported in the literature; however, qualitative visual inspection can sometimes catch errors or other issues that may be missed by quantitative metrics alone. In this paper, we describe our methods for performing QC of rs-fMRI data using software-generated quantitative and qualitative output and trained visual inspection.
Results: The data provided for this QC paper had relatively low motion-censoring, thus quantitative QC resulted in no exclusions. Qualitative checks of the data resulted in limited exclusions due to potential incidental findings and failed pre-processing scripts.
Conclusion: Visual inspection in addition to the review of quantitative QC metrics is an important component to ensure high quality and accuracy in rs-fMRI data analysis
Weak Lensing from Space I: Instrumentation and Survey Strategy
A wide field space-based imaging telescope is necessary to fully exploit the
technique of observing dark matter via weak gravitational lensing. This first
paper in a three part series outlines the survey strategies and relevant
instrumental parameters for such a mission. As a concrete example of hardware
design, we consider the proposed Supernova/Acceleration Probe (SNAP). Using
SNAP engineering models, we quantify the major contributions to this
telescope's Point Spread Function (PSF). These PSF contributions are relevant
to any similar wide field space telescope. We further show that the PSF of SNAP
or a similar telescope will be smaller than current ground-based PSFs, and more
isotropic and stable over time than the PSF of the Hubble Space Telescope. We
outline survey strategies for two different regimes - a ``wide'' 300 square
degree survey and a ``deep'' 15 square degree survey that will accomplish
various weak lensing goals including statistical studies and dark matter
mapping.Comment: 25 pages, 8 figures, 1 table, replaced with Published Versio
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