1,985 research outputs found
Lighting hygiene, melanopic daylight efficacy ratios and energy efficiency
The second Manchester Workshop recommended minimum daytime eye-level exposures to light, and evening and night-time maximums, in terms melanopic equivalent daylight illuminance (melanopic EDI). In integrative lighting and healthy light hygiene regimes, the evening calls for lights with low melanopic daylight efficacy ratios (melanopic DERs) to realize sufficient illuminance for visual function whilst limiting melanopic EDI. In the daytime, where electric lighting is needed, a higher melanopic DER is desirable. Night -time may be considered an extreme version of evening, with a need for light by exception. It is a matter of social and economic importance that daytime, evening and night -time spectral objectives can each strongly conflict with the use of luminous efficacy to determine how much net positive utility derives from electrical energy and its CO2 footprint. This paper compares LED products, including melanopic engineered lighting systems, it discusses electrical energy efficiency implications and introduces the concept of âmelanopic efficacyâ
Lighting hygiene, melanopic daylight efficacy ratios and energy efficiency
The second Manchester Workshop recommended minimum daytime eye-level exposures to light, and evening and night-time maximums, in terms melanopic equivalent daylight illuminance (melanopic EDI). In integrative lighting and healthy light hygiene regimes, the evening calls for lights with low melanopic daylight efficacy ratios (melanopic DERs) to realize sufficient illuminance for visual function whilst limiting melanopic EDI. In the daytime, where electric lighting is needed, a higher melanopic DER is desirable. Night -time may be considered an extreme version of evening, with a need for light by exception. It is a matter of social and economic importance that daytime, evening and night -time spectral objectives can each strongly conflict with the use of luminous efficacy to determine how much net positive utility derives from electrical energy and its CO2 footprint. This paper compares LED products, including melanopic engineered lighting systems, it discusses electrical energy efficiency implications and introduces the concept of âmelanopic efficacyâ
Report on the Workshop Use and Application of the new CIE s 026/e:2018, Metrology for ipRGC-influenced responses to light âspecifying light for its eye-mediated non-visual effects in humansâ
In December 2018, the international standard CIE S 026/E:2018 âCIE System for Metrology of Optical Radiation for ipRGC-Influenced Responses to Lightâ (doi.org/10.25039/S026.2018) was published. This standard defines spectral sensitivity functions, quantities and metrics to describe the ability of optical radiation to stimulate each of the five retinal photoreceptor classes that can contribute, via the melanopsin-containing intrinsically-photosensitive retinal ganglion cells (ipRGCs), to the retinally mediated non-visual effects of light in humans. This one-hour workshop started with four 10 minute presentations about the standard, followed by a general discussion and questions. The four presentations focused on the following topics:1) Introduction to CIE S 026 and its quantities (Luc Schlangen)2) Demonstration of toolkit (in preparation) to calculate CIE S 026 quantities (Presented by Luc Schlangen on behalf of Luke Price)3) Accounting for field of view (David Sliney)4) ipRGCs and pupil response (Manuel Spitschan
Phylogeny of Geomydoecus and Thomomydoecus pocket gopher lice (phthiraptera, trichodectidae) inferred from cladistic analysis of adult and first instar morphology
The phylogeny for all 122 species and subspecies of chewing lice of the genera Geomydoecus and Thomomydoecus (Phthiraptera: Trichodectidae) hosted by pocket gophers (Rodentia: Geomyidae) is estimated by a cladistic analysis of fifty-eight morphological characters obtained from adults and first instars. The data set has considerable homoplasy, but still contains phylogenetic information. The phylogeny obtained is moderately resolved and, with some notable exceptions, supports the species complexes proposed by Hellenthal and Price over the the last two decades. The subgenera G. (Thaelerius) and T. (Thomomydoecus) are both shown to be monophyletic, but the monophly of subgenus T. (Jamespattonius) could not be confirmed, perhaps due to the lack of first-instar data for one of its component species. The nominate subgenus of Geomydoecus may be monophyletic, but our cladogram was insufficiently resolved to corroborate this. Mapping the pocket gopher hosts onto the phylogeny reveals a consistent pattern of louse clades being restricted to particular genera or subgenera of gophers, but the history of the host-parasite association appears complex and will require considerable effort to resolve
A gravitational memory effect in "boosted" black hole perturbation theory
Black hole perturbation theory, or more generally, perturbation theory on a
Schwarzschild bockground, has been applied in several contexts, but usually
under the simplifying assumption that the ADM momentum vanishes, namely, that
the evolution is carried out and observed in the ``center of momentum frame''.
In this paper we consider some consequences of the inclusion of a non vanishing
ADM momentum in the initial data. We first provide a justification for the
validity of the transformation of the initial data to the ``center of momentum
frame'', and then analyze the effect of this transformation on the
gravitational wave amplitude. The most significant result is the possibility of
a type of gravitational memory effect that appears to have no simple relation
with the well known Christodoulou effect.Comment: REVTexIV, 15 pages, 2 EPS figure
Performance of a direct steam generation solar thermal power plant for electricity production as a function of the solar multiple
This paper describes the influence of the solar multiple on the annual performance of parabolic trough solar thermal power plants with direct steam generation (DSG). The reference system selected is a 50 M We DSG power plant, with thermal storage and auxiliary natural gas-fired boiler. It is considered that both systems are necessary for an optimum coupling to the electricity grid. Although thermal storage is an opening issue for DSG technology, it gives an additional degree of freedom for plant performance optimization. Fossil hybridization is also a key element if a reliable electricity production must be guaranteed for a defined time span. Once the yearly parameters of the solar power plant are calculated, the economic analysis is performed, assessing the effect of the solar multiple in the levelized cost of electricity, as well as in the annual natural gas consumption
The collision of two slowly rotating, initially non boosted, black holes in the close limit
We study the collision of two slowly rotating, initially non boosted, black
holes in the close limit. A ``punctures'' modification of the Bowen - York
method is used to construct conformally flat initial data appropriate to the
problem. We keep only the lowest nontrivial orders capable of giving rise to
radiation of both gravitational energy and angular momentum. We show that even
with these simplifications an extension to higher orders of the linear
Regge-Wheeler-Zerilli black hole perturbation theory, is required to deal with
the evolution equations of the leading contributing multipoles. This extension
is derived, together with appropriate extensions of the Regge-Wheeler and
Zerilli equations. The data is numerically evolved using these equations, to
obtain the asymptotic gravitational wave forms and amplitudes. Expressions for
the radiated gravitational energy and angular momentum are derived and used
together with the results of the numerical evolution to provide quantitative
expressions for the relative contribution of different terms, and their
significance is analyzed.Comment: revtex, 18 pages, 2 figures. Misprints corrected. To be published in
Phys. Rev.
Exploring trade-offs between landscape impact, land use and resource quality for onshore variable renewable energy : An application to Great Britain
The authors gratefully acknowledge the contributions of David Schlund, who carried out some of the wind analysis whilst a Student Assistant at KIT, as well as Camille Moutard, upon whose Master Thesis at DTU this article builds (Assessing the âacceptableâ onshore wind potential in the UK, 2019, https://findit.dtu.dk/en/catalog/2451029061). The authors also gratefully acknowledge the anonymous feedback from three anonymous referees on an earlier version of this paper. The usual disclaimer applies. Credit author statement Conceptualisation: RM, IM, JMW; Methodology: all; Software: RM, IM, JMW, JP, SP; Data curation: RM, IM, JMW, JP, SP; Writing â Original Draft: All, Writing â Review & Editing: All; Visualisation: IM, JMW, JP, SP; Supervision: RM; Project Administration: RM.Peer reviewedPublisher PD
Scalar Synchrotron Radiation in the Schwarzschild-anti-de Sitter Geometry
We present a complete relativistic analysis for the scalar radiation emitted
by a particle in circular orbit around a Schwarzschild-anti-de Sitter black
hole. If the black hole is large, then the radiation is concentrated in narrow
angles- high multipolar distribution- i.e., the radiation is synchrotronic.
However, small black holes exhibit a totally different behavior: in the small
black hole regime, the radiation is concentrated in low multipoles. There is a
transition mass at , where is the AdS radius. This behavior is
new, it is not present in asymptotically flat spacetimes.Comment: 13 pages, 6 figures, published version. References adde
Strongly bound mesons at finite temperature and in magnetic fields from AdS/CFT
We study mesons in N=4 super Yang-Mills theory with fundamental flavors added
at large 't Hooft coupling using the gauge/gravity correspondence. High-spin
mesons are well described by using semiclassical string configurations. We
determine the meson spectrum at finite temperature and in a background magnetic
field.Comment: 15 pages, 11 figures; v2: references adde
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