9,904 research outputs found
Editorial: Biomechatronics: Harmonizing Mechatronic Systems With Human Beings.
There has been a growing body of research in the recent years on human-robot interactions, human-machine interfaces and intelligent devices that are centered around human application, however, these works by and large lacked in focus on how to harmonize the interactions between mechatronic systems and users in the loop. This is one of the key areas for evaluating the success of any mechatronic system implementation on human. The collection of papers in this volume is touching upon the frontiers of this research area as to how the efficacy of such biomechatronic systems could be evaluated and improved. There are a total of 19 papers looking into various aspects of human-machine interfaces (HMIs) using electromyography (EMG) and electroencephalography (EEG), tactile feedback, external devices such as exoskeletons and prosthetic devices for assistance and rehabilitation, novel techniques like machine learning and intelligent computation, and experimental evaluation or validation. The following paragraphs aim to give a glimpse of the contents presented in this eBook. Specifically, these are categorized under three distinct headings: (A) Novel exoskeletons for assistance and training, (B) Advanced human-machine interfaces in biomechatronics, and (C) Experimental outcomes and validation
Test results of Spacelab 2 infrared telescope focal plane
The small helium cooled infrared telescope for Spacelab 2 is designed for sensitive mapping of extended, low-surface-brightness celestial sources as well as highly sensitive investigations of the shuttle contamination environment (FPA) for this mission is described as well as the design for a thermally isolated, self-heated J-FET transimpedance amplifier. This amplifier is Johnson noise limited for feedback resistances from less than 10 to the 8th power Omega to greater than 2 x 10 to the 10th power Omega at T = 4.2K. Work on the focal plane array is complete. Performance testing for qualification of the flight hardware is discussed, and results are presented. All infrared data channels are measured to be background limited by the expected level of zodiacal emission
A balloon-borne 1 meter telescope for far-infrared astronomy
The flight of a balloon-borne one-meter telescope for infrared astronomy in the wavelength interval of 40 to 240 microns is discussed. The gyro-stabilized telescope mapped the intensity of the far infrared radiation from NGC 7538, Mars, the Orion Nebula, and W3 with a resolution of one minute and from selected regions of these sources with a resolution of 30 seconds. The infrared detection is described and its capabilities are analyzed. The instrumentation, orientation system, and modes of observation of the telescope are defined
Precise nondivergent analytic formulas for the radiative corrections to the beta energy spectrum in hyperon semileptonic decays over the entire Dalitz plot
Very accurate analytical expressions for the radiative corrections of
unpolarized hyperons semileptonic decays of charged and neutral baryons have
been obtained in the recent past. Some of these formulas contain logarithmic
singularities at the edges of the Dalitz plot for the three- and four-body
decays. These singularities are analyzed and integrated analytically to obtain
new divergentless formulas for the energy spectrum of the produced beta
particle. The new equations contain terms of the order alpha times the momentum
transfer, are applicable to any beta decay process and are suitable for a
model-independent experimental analysis.Comment: 22 pages, 4 figure
Plasmon tunability in metallodielectric metamaterials
The dielectric properties of metamaterials consisting of periodically
arranged metallic nanoparticles of spherical shape are calculated by rigorously
solving Maxwell's equations. Effective dielectric functions are obtained by
comparing the reflectivity of planar surfaces limiting these materials with
Fresnel's formulas for equivalent homogeneous media, showing mixing and
splitting of individual-particle modes due to inter-particle interaction.
Detailed results for simple cubic and fcc crystals of aluminum spheres in
vacuum, silver spheres in vacuum, and silver spheres in a silicon matrix are
presented. The filling fraction of the metal f is shown to determine the
position of the plasmon modes of these metamaterials. Significant deviations
are observed with respect to Maxwell-Garnett effective medium theory for large
f, and multiple plasmons are predicted to exist in contrast to Maxwell-Garnett
theory.Comment: 6 pages, 4 figure
Flickering of 1.3 cm Sources in Sgr B2: Towards a Solution to the Ultracompact HII Region Lifetime Problem
Accretion flows onto massive stars must transfer mass so quickly that they
are themselves gravitationally unstable, forming dense clumps and filaments.
These density perturbations interact with young massive stars, emitting
ionizing radiation, alternately exposing and confining their HII regions. As a
result, the HII regions are predicted to flicker in flux density over periods
of decades to centuries rather than increasing monotonically in size as
predicted by simple Spitzer solutions. We have recently observed the Sgr B2
region at 1.3 cm with the VLA in its three hybrid configurations (DnC, CnB and
BnA) at a resolution of 0.25''. These observations were made to compare in
detail with matched continuum observations from 1989. At 0.25'' resolution, Sgr
B2 contains 41 UC HII regions, 6 of which are hypercompact. The new
observations of Sgr B2 allow comparison of relative peak flux densites for the
HII regions in Sgr B2 over a 23 year time baseline (1989-2012) in one of the
most source-rich massive star forming regions in the Milky Way. The new 1.3 cm
continuum images indicate that four of the 41 UC HII regions exhibit
significant changes in their peak flux density, with one source (K3) dropping
in peak flux density, and the other 3 sources (F10.303, F1 and F3) increasing
in peak flux density. The results are consistent with statistical predictions
from simulations of high mass star formation, suggesting that they offer a
solution to the lifetime problem for ultracompact HII regions.Comment: 12 pages, 3 figures, Accepted for publication in the Astrophysical
Journal Letter
Programmability and Performance of Parallel ECS-based Simulation of Multi-Agent Exploration Models
While the traditional objective of parallel/distributed simulation techniques has been mainly in improving performance and making very large models tractable, more recent research trends targeted complementary aspects, such as the “ease of programming”. Along this line, a recent proposal called Event and Cross State (ECS) synchronization, stands as a solution allowing to break the traditional programming rules proper of Parallel Discrete Event Simulation (PDES) systems, where the application code processing a specific event is only allowed to access the state (namely the memory image) of the target simulation object. In fact with ECS, the programmer is allowed to write ANSI-C event-handlers capable of accessing (in either read or write mode) the state of whichever simulation object included in the simulation model. Correct concurrent execution of events, e.g., on top of multi-core machines, is guaranteed by ECS with no intervention by the programmer, who is in practice exposed to a sequential-style programming model where events are processed one at a time, and have the ability to access the current memory image of the whole simulation model, namely the collection of the states of any involved object. This can strongly simplify the development of specific models, e.g., by avoiding the need for passing state information across concurrent objects in the form of events. In this article we investigate on both programmability and performance aspects related to developing/supporting a multi-agent exploration model on top of the ROOT-Sim PDES platform, which supports ECS
Generalized polarizabilities and the spin-averaged amplitude in virtual Compton scattering off the nucleon
We discuss the low-energy behavior of the spin-averaged amplitude of virtual
Compton scattering (VCS) off a nucleon.
Based on gauge invariance, Lorentz invariance and the discrete symmetries, it
is shown that to first order in the frequency of the final real photon only two
generalized polarizabilities appear.
Different low-energy expansion schemes are discussed and put into
perspective.Comment: 13 pages, 1 postscript figure, Revtex using eps
Rhythm and Vowel Quality in Accents of English
In a sample of 27 speakers of Scottish Standard English two notoriously variable consonantal features are investigated: the contrast of /m/ and /w/ and non-prevocalic /r/, the latter both in terms of its presence or absence and the phonetic form it takes, if present. The pattern of realisation of non-prevocalic /r/ largely confirms previously reported findings. But there are a number of surprising results regarding the merger of /m/ and /w/ and the loss of non-prevocalic /r/: While the former is more likely to happen in younger speakers and females, the latter seems more likely in older speakers and males. This is suggestive of change in progress leading to a loss of the /m/ - /w/ contrast, while the variation found in non-prevocalic /r/ follows an almost inverse sociolinguistic pattern that does not suggest any such change and is additionally largely explicable in language-internal terms. One phenomenon requiring further investigation is the curious effect direct contact with Southern English accents seems to have on non-prevocalic /r/: innovation on the structural level (i.e. loss) and conservatism on the realisational level (i.e. increased incidence of [r] and [r]) appear to be conditioned by the same sociolinguistic factors
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