8,947 research outputs found
Metaphoric competence and communicative language ability
Recent developments in cognitive linguistics have highlighted the importance as well as the ubiquity of metaphor in language. Despite this, the ability of second language learners to use metaphors is often still not seen as a core ability. In this paper, we take a model of communicative competence that has been widely influential in both language teaching and language testing, namely Bachman (1990), and argue, giving a range of examples of language use and learner difficulty, that metaphoric competence has in fact an important role to play in all areas of communicative competence. In other words, it can contribute centrally to grammatical competence, textual competence, illocutionary competence, sociolinguistic competence, and strategic competence. Metaphor is thus highly relevant to second language learning, teaching and testing, from the earliest to the most advanced stages of learning
Analytical dead-band compensation for ZCS modulation applied to hybrid Si-SiC dual active bridge
© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper proposes a triangular modulation with zero current switching (ZCS) for a hybrid Si-SiC isolated bidirectional DC-DC converter (IBDC). Three of the four legs in the IBDC operate at ZCS and use Si IGBTs, while the fourth operates at zero voltage switching (ZVS) and uses SiC MOSFET. In that case, the turn-off switching losses are concentrated regardless of the direction of the power. The main contribution of this paper resides in the proposed dead-band compensation mechanism. This dead-band compensation is crucial when addressing ZCS modulation and improves the overall efficiency of the full operating range. As a co-benefit, the proposed mix of semiconductor technologies can result in an effective cost reduction compared with a full SiC IBDC. The paper contains a detailed explanation of the implemented modulation applied to an IBDC. The paper contributes to deploy a theoretical implementation where the effect of parasitic capacitance on semiconductors during the dead-band is analytically considered. The presented method results are validated on a laboratory set-up using a 20 kW - 40 kHz hybrid Si-SiC IBDC.Postprint (author's final draft
A Practical Compensation Method for Differential Column Shortenings in High-rise Reinforced Concrete Buildings
High-rise reinforced concrete buildings have technical, economic and environmental advantages for high density development and they have become a distinctive feature for densely populated urban areas around the world. For this purpose, structural design of high-rise reinforced concrete buildings have become forward and particularly serviceability requirements gained more interest. Differential shortening of vertical members is one of the serviceability requirements; however, only a limited number of studies exist. In this study, a practical compensation method was proposed for the differential shortening of columns and shear walls in high-rise reinforced concrete buildings. In the proposed compensation method, vertical members were grouped and the total error was aimed to be minimized by penalizing the higher shortening differences in the groups to simplify the process of building construction. In order to validate the proposed method, a 32-storey high-rise building that was built in Izmir Turkey was investigated considering both the construction sequence and time-dependent effects as shrinkage and creep. Vertical shortening of columns and shear walls in the tower part of the building were calculated. Uniform-grouped compensation method and the proposed penalized errors compensation method with using L1-norm and L2-norm were applied for differential shortenings of columns and shear walls with considering different numbers of member groups. The magnitude of errors for each compensation method was presented and evaluated. Results of the numerical study reveal that the proposed penalized errors compensation method was capable of determining the compensation errors by minimizing the maximum errors efficiently
Pioneers in the Victorian provinces: veterinarians, public health and the urban animal economy
From the 1850s in Britain, concerns were growing about the role of animals in transmitting disease to man, whether through the food chain or through infection. While London is often seen as providing a model for public health reform, it was the great provincial cities that initiated veterinary involvement in public health in the closing years of the century. The emergence of this new strand of public health activity is the subject of this paper
Prognosis of the state of health of a person under spaceflight conditions
Methods of predicting the state of health and human efficiency during space flight are discussed. Diversity of reactions to the same conditions, development of extrapolation methods of prediction, and isolation of informative physiological indexes are among the factors considered
Modern optical astronomy: technology and impact of interferometry
The present `state of the art' and the path to future progress in high
spatial resolution imaging interferometry is reviewed. The review begins with a
treatment of the fundamentals of stellar optical interferometry, the origin,
properties, optical effects of turbulence in the Earth's atmosphere, the
passive methods that are applied on a single telescope to overcome atmospheric
image degradation such as speckle interferometry, and various other techniques.
These topics include differential speckle interferometry, speckle spectroscopy
and polarimetry, phase diversity, wavefront shearing interferometry,
phase-closure methods, dark speckle imaging, as well as the limitations imposed
by the detectors on the performance of speckle imaging. A brief account is
given of the technological innovation of adaptive-optics (AO) to compensate
such atmospheric effects on the image in real time. A major advancement
involves the transition from single-aperture to the dilute-aperture
interferometry using multiple telescopes. Therefore, the review deals with
recent developments involving ground-based, and space-based optical arrays.
Emphasis is placed on the problems specific to delay-lines, beam recombination,
polarization, dispersion, fringe-tracking, bootstrapping, coherencing and
cophasing, and recovery of the visibility functions. The role of AO in
enhancing visibilities is also discussed. The applications of interferometry,
such as imaging, astrometry, and nulling are described. The mathematical
intricacies of the various `post-detection' image-processing techniques are
examined critically. The review concludes with a discussion of the
astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics,
2002, to appear in April issu
Ultra-stable implanted 83Rb/83mKr electron sources for the energy scale monitoring in the KATRIN experiment
The KATRIN experiment aims at the direct model-independent determination of
the average electron neutrino mass via the measurement of the endpoint region
of the tritium beta decay spectrum. The electron spectrometer of the MAC-E
filter type is used, requiring very high stability of the electric filtering
potential. This work proves the feasibility of implanted 83Rb/83mKr calibration
electron sources which will be utilised in the additional monitor spectrometer
sharing the high voltage with the main spectrometer of KATRIN. The source
employs conversion electrons of 83mKr which is continuously generated by 83Rb.
The K-32 conversion line (kinetic energy of 17.8 keV, natural line width of 2.7
eV) is shown to fulfill the KATRIN requirement of the relative energy stability
of +/-1.6 ppm/month. The sources will serve as a standard tool for continuous
monitoring of KATRIN's energy scale stability with sub-ppm precision. They may
also be used in other applications where the precise conversion lines can be
separated from the low energy spectrum caused by the electron inelastic
scattering in the substrate.Comment: 30 pages, 10 figures, 1 table, minor revision of the preprint,
accepted by JINST on 5.2.201
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