3,061 research outputs found
Inflatable device for installing strain gage bridges
Methods and devices for installing in a tubular shaft multiple strain gages are disclosed with focus on a method and a device for pneumatically forcing strain gages into seated engagement with the internal surfaces of a tubular shaft in an installation of multiple strain gages in a tubular shaft. The strain gages or other electron devices are seated in a template-like component which is wrapped about a pneumatically expansible body. The component is inserted into a shaft and the body is pneumatically expanded after a suitable adhesive was applied to the surfaces
An approach for solving the boundary free edge difficulties in SPH modelling: application to a viscous accretion disc in close binaries
In this work, we propose a SPH interpolating Kernel reformulation suitable
also to treat free edge boundaries in the computational domain. Application to
both inviscid and viscous stationary low compressibility accretion disc models
in Close Binaries (CB) are shown. The investigation carried out in this paper
is a consequence of the fact that a low compressibility modelling is crucial to
check numerical reliability.
Results show that physical viscosity supports a well-bound accretion disc
formation, despite the low gas compressibility, when a Gaussian-derived Kernel
(from the Error Function) is assumed, in extended particle range - whose Half
Width at Half Maximum (HWHM) is fixed to a constant value - without any
spatial restrictions on its radial interaction (hereinafter GASPHER). At the
same time, GASPHER ensures adequate particle interpolations at the boundary
free edges. Both SPH and adaptive SPH (hereinafter ASPH) methods lack accuracy
if there are not constraints on the boundary conditions, in particular at the
edge of the particle envelope: Free Edge (FE) conditions. In SPH, an
inefficient particle interpolation involves a few neighbour particles; instead,
in the second case, non-physical effects involve both the boundary layer
particles themselves and the radial transport.
Either in a regime where FE conditions involve the computational domain, or
in a viscous fluid dynamics, or both, a GASPHER scheme can be rightly adopted
in such troublesome physical regimes. Despite the applied low compressibiity
condition, viscous GASPHER model shows clear spiral pattern profiles
demonstrating the better quality of results compared to SPH viscous ones.
Moreover a successful comparison of results concerning GASPHER 1D inviscid
shock tube with analytical solution is also reported.Comment: 18 pages, 12 figure
Smart-device based motor function battery, A
2018 Fall.Includes bibliographical references.Growth in the older population will increase the overall impact of age-related neurological disorders. Aging and neurological conditions share features such as impaired motor function and physical dysfunction including reduced muscle strength and power, slowness of movement, increased movement variability and balance dysfunction. Successful performance of daily activities and maintenance of mobility is key to independence and quality of life. Therefore, tracking changes in physical function is critical in gauging quality of life. However truly quantitative measures of physical capacity often require the use of expensive, lab-based equipment. Smart devices contain sensitive tri-axial accelerometers and gyroscopes that measure acceleration and rotation and offer a more cost-effective, portable yet still quantitative means of physical assessment. The purpose is to describe an iPod Touch-instrumented test battery designed to assess features of physical and motor function often shared by normal aging and age-related movement disorders. We have been assessing the correlation between measures taken from expensive lab devices and the iPod Touch smart device for a variety of movements. We developed and tested a multi-item smart device-based battery of motor tasks that addresses motor variability, slowness and postural instability across a range of young, healthy college students. By changing the location of the device we can assess upper and lower limb movement speed and power, hand tremor, or postural control. We have also used previously validated lab devices concurrently with the smart device, which allows us to correlate the results between devices to assess the extent of the association between devices. Outcomes such as peak acceleration and variability of movements can be obtained. Generally, the smart device demonstrated strong correlations with the lab grade sensors for all motor tasks. Furthermore, the smart device was also correlated with the accelerometer across a large range of speed and variability. Strong correlations were seen in ballistic arm and leg tasks, tremor, and postural control assessments. This finding suggests that the smart device can sufficiently assess a broad range of functional capacity. This battery can then be used to study populations exhibiting motor impairment, ranging from older adults, to neurological patients. Using the sensors on the smart device, this testing can be administered remotely and inexpensively by non-experts, providing cost-effective, mobile, user- and patient-friendly physical function testing. More importantly, accessibility of testing is increased while retaining quantitative precision. This should aid in quantifying disease progression and response to pharmacological or exercise/rehabilitative intervention, with the goal of improved function and quality of life in those with impairment
Climate change, the green economy and reimagining the city: the case of structurally disadvantaged European maritime port cities
The concept of the New Environmental Politics of Urban Development (NEPUD) examines the impact of international and national environmental regulation on the politics of urban development. The NEPUD concept emerged from case studies of environmental governance in entrepreneurial cities. However, little is known about the concept’s relevance for less competitive cities, especially urban centres facing profound problems associated with economic decline, social deprivation and negative external images or ‘structurally disadvantaged cities.’ This paper examines how the NEPUD has played out within two structurally disadvantaged maritime port cities in Northern Europe, Hull (UK) and Bremerhaven (Germany). Both cities face serious social and economic challenges associated with long-term industrial decline, such as high unemployment rates, low skill levels, economic peripherality, and poor external images. Nevertheless, new opportunities opened up by climate change and the green economy have prompted political actors in Hull and Bremerhaven to build new alliances between local government, business and civil society and enhance governance capacities on climate change and green urban development. Highlighting similarities and differences between these two places, the paper reveals how climate change regulations provide opportunities for certain structurally disadvantaged cities to attract ‘green jobs’ and transform their external image
Angular Signatures of Annihilating Dark Matter in the Cosmic Gamma-Ray Background
The extragalactic cosmic gamma-ray background (CGB) is an interesting channel
to look for signatures of dark matter annihilation. In particular, besides the
imprint in the energy spectrum, peculiar anisotropy patterns are expected
compared to the case of a pure astrophysical origin of the CGB. We take into
account the uncertainties in the dark matter clustering properties on
sub-galactic scales, deriving two possible anisotropy scenarios. A clear dark
matter angular signature is achieved when the annihilation signal receives only
a moderate contribution from sub-galactic clumps and/or cuspy haloes.
Experimentally, if galactic foregrounds systematics are efficiently kept under
control, the angular differences are detectable with the forthcoming GLAST
observatory, provided that the annihilation signal contributes to the CGB for a
fraction >10-20%. If, instead, sub-galactic structures have a more prominent
role, the astrophysical and dark matter anisotropies become degenerate,
correspondingly diluting the DM signature. As complementary observables we also
introduce the cross-correlation between surveys of galaxies and the CGB and the
cross-correlation between different energy bands of the CGB and we find that
they provide a further sensitive tool to detect the dark matter angular
signatures.Comment: 13 pages, 8 figures; improved discussion; matches published versio
Anthropogenic Transformation at Angel Mounds: Construction, Chronology and Context for Mounds A and F
Investigations at Angel Mounds since 2005 have tackled a series of questions related to anthropogenic transformation, the built landscape and mound construction. During the 2013 NSF-sponsored research, investigations focused on Mound A’s lower platform and the reopening of Mound F. Results from these investigations revealed a series of use-surfaces on Mound A’s lower platform with evidence for burning episodes that were followed by reconstruction. Excavations on Mound F also revealed a burning episode associated with a structure on the “inner mound,” as well as a sub-mound structure and features demonstrating use of the space prior to mound construction
Cognitive influences in language evolution:Psycholinguistic predictors of loan word borrowing
Languages change due to social, cultural, and cognitive influences. In this paper, we provide an assessment of these cognitive influences on diachronic change in the vocabulary. Previously, tests of stability and change of vocabulary items have been conducted on small sets of words where diachronic change is imputed from cladistics studies. Here, we show for a substantially larger set of words that stability and change in terms of documented borrowings of words into English and into Dutch can be predicted by psycholinguistic properties of words that reflect their representational fidelity. We found that grammatical category, word length, age of acquisition, and frequency predict borrowing rates, but frequency has a non-linear relationship. Frequency correlates negatively with probability of borrowing for high-frequency words, but positively for low-frequency words. This borrowing evidence documents recent, observable diachronic change in the vocabulary enabling us to distinguish between change associated with transmission during language acquisition and change due to innovations by proficient speakers
Hydrodynamic simulations with the Godunov SPH
We present results based on an implementation of the Godunov Smoothed
Particle Hydrodynamics (GSPH), originally developed by Inutsuka (2002), in the
GADGET-3 hydrodynamic code. We first review the derivation of the GSPH
discretization of the equations of moment and energy conservation, starting
from the convolution of these equations with the interpolating kernel. The two
most important aspects of the numerical implementation of these equations are
(a) the appearance of fluid velocity and pressure obtained from the solution of
the Riemann problem between each pair of particles, and (b the absence of an
artificial viscosity term. We carry out three different controlled
hydrodynamical three-dimensional tests, namely the Sod shock tube, the
development of Kelvin-Helmholtz instabilities in a shear flow test, and the
"blob" test describing the evolution of a cold cloud moving against a hot wind.
The results of our tests confirm and extend in a number of aspects those
recently obtained by Cha (2010): (i) GSPH provides a much improved description
of contact discontinuities, with respect to SPH, thus avoiding the appearance
of spurious pressure forces; (ii) GSPH is able to follow the development of
gas-dynamical instabilities, such as the Kevin--Helmholtz and the
Rayleigh-Taylor ones; (iii) as a result, GSPH describes the development of curl
structures in the shear-flow test and the dissolution of the cold cloud in the
"blob" test.
We also discuss in detail the effect on the performances of GSPH of changing
different aspects of its implementation. The results of our tests demonstrate
that GSPH is in fact a highly promising hydrodynamic scheme, also to be coupled
to an N-body solver, for astrophysical and cosmological applications.
[abridged]Comment: 19 pages, 13 figures, MNRAS accepted, high resolution version can be
obtained at
http://adlibitum.oats.inaf.it/borgani/html/papers/gsph_hydrosim.pd
Equilibrium Configurations of Strongly Magnetized Neutron Stars with Realistic Equations of State
We investigate equilibrium sequences of magnetized rotating stars with four
kinds of realistic equations of state (EOSs) of SLy (Douchin et al.), FPS
(Pandharipande et al.), Shen (Shen et al.), and LS (Lattimer & Swesty).
Employing the Tomimura-Eriguchi scheme to construct the equilibrium
configurations. we study the basic physical properties of the sequences in the
framework of Newton gravity. In addition we newly take into account a general
relativistic effect to the magnetized rotating configurations. With these
computations, we find that the properties of the Newtonian magnetized stars,
e.g., structure of magnetic field, highly depends on the EOSs.
The toroidal magnetic fields concentrate rather near the surface for Shen and
LS EOSs than those for SLy and FPS EOSs. The poloidal fields are also affected
by the toroidal configurations. Paying attention to the stiffness of the EOSs,
we analyze this tendency in detail. In the general relativistic stars, we find
that the difference due to the EOSs becomes small because all the employed EOSs
become sufficiently stiff for the large maximum density, typically greater than
. The maximum baryon mass of the magnetized stars
with axis ratio increases about up to twenty percents for that of
spherical stars. We furthermore compute equilibrium sequences at finite
temperature, which should serve as an initial condition for the hydrodynamic
study of newly-born magnetars. Our results suggest that we may obtain
information about the EOSs from the observation of the masses of magnetars.Comment: submitted to MNRA
The X-ray Ridge Surrounding Sgr A* at the Galactic Center
We present the first detailed simulation of the interaction between the
supernova explosion that produced Sgr A East and the wind-swept inner ~ 2-pc
region at the Galactic center. The passage of the supernova ejecta through this
medium produces an X-ray ridge ~ 9'' to 15'' to the NE of the supermassive
black hole Sagittarius A* (Sgr A*). We show that the morphology and X-ray
intensity of this feature match very well with recently obtained Chandra
images, and we infer a supernova remnant age of less than 2,000 years. This
young age--a factor 3--4 lower than previous estimates--arises from our
inclusion of stellar wind effects in the initial (pre-explosion) conditions in
the medium. The supernova does not clear out the central ~ 0.2-pc region around
Sgr~A* and does not significantly alter the accretion rate onto the central
black hole upon passage through the Galactic center.Comment: 10 pages, 3 figures, submitted to ApJ
- …