3,621 research outputs found
Ir(III) complexes of diamine ligands for asymmetric ketone hydrogenation
The use of a combination of IrCl3 with a series of ligands derived from the C2-symmetric diamine diphenylethanediamine (DPEN) forms a catalyst capable of the asymmetric hydrogenation of ketones in up to 85% ee
Extension and approximation of -subharmonic functions
Let be a bounded domain, and let be a
real-valued function defined on the whole topological boundary . The aim of this paper is to find a characterization of the functions
which can be extended to the inside to a -subharmonic function under
suitable assumptions on . We shall do so by using a function algebraic
approach with focus on -subharmonic functions defined on compact sets. We
end this note with some remarks on approximation of -subharmonic functions
Spinning dust emission: the effect of rotation around a non-principal axis
We investigate the rotational emission from dust grains that rotate around
non- principal axes. We argue that in many phases of the interstellar medium,
the smallest grains, which dominate spinning dust emission, are likely to have
their nutation state (orientation of principal axes relative to the angular
momentum vector) randomized during each thermal spike. We recompute the
excitation and damping rates associated with rotational emission from the grain
permanent dipole, grain-plasma interactions, infrared photon emission, and
collisions. The resulting spinning dust spectra gener- ally show a shift toward
higher emissivities and peak frequencies relative to previous calculations.Comment: Version accepted for publication in MNRAS. The derivation of the
emission spectrum was clarified. The companion code, SPDUST.2, can be
downloaded from http://www.tapir.caltech.edu/~yacine/spdust/spdust.htm
Hardy's inequality for functions vanishing on a part of the boundary
We develop a geometric framework for Hardy's inequality on a bounded domain
when the functions do vanish only on a closed portion of the boundary.Comment: 26 pages, 2 figures, includes several improvements in Sections 6-8
allowing to relax the assumptions in the main results. Final version
published at http://link.springer.com/article/10.1007%2Fs11118-015-9463-
K 1-6: an asymmetric planetary nebula with a binary central star
We present new imaging data and archival multiwavelength observations of the
little studied emission nebula K 1-6 and its central star. Narrow-band images
in H-alpha (+ [NII]) and [OIII] taken with the Faulkes Telescope North reveal a
stratified, asymmetric, elliptical nebula surrounding a central star which has
the colours of a late G- or early K-type subgiant or giant. GALEX ultraviolet
images reveal a very hot subdwarf or white dwarf coincident in position with
this star. The cooler, optically dominant star is strongly variable with a
period of 21.312 +/- 0.008 days, and is possibly a high amplitude member of the
RS CVn class, although an FK Com classification is also possible. Archival
ROSAT data provide good evidence that the cool star has an active corona. We
conclude that K 1-6 is most likely an old bona fide planetary nebula at a
distance of ~1.0 kpc, interacting with the interstellar medium, and containing
a binary or ternary central star. The observations and data analyses reported
in this paper were conducted in conjunction with Year 11 high school students
as part of an Australian Research Council Linkage Grant science education
project, denoted Space To Grow, conducted jointly by professional astronomers,
educational researchers, teachers, and high-school students.Comment: 13 pages, 5 figures, accepted by the Publications of the Astronomical
Society of Australia (PASA
A Time Projection Chamber with GEM-Based Readout
For the International Large Detector concept at the planned International
Linear Collider, the use of time projection chambers (TPC) with micro-pattern
gas detector readout as the main tracking detector is investigated. In this
paper, results from a prototype TPC, placed in a 1 T solenoidal field and read
out with three independent GEM-based readout modules, are reported. The TPC was
exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for
reconstructing hits, the measurement of the drift velocity, the space point
resolution and the control of field inhomogeneities are presented.Comment: 22 pages, 19 figure
Nucleation of a sodium droplet on C60
We investigate theoretically the progressive coating of C60 by several sodium
atoms. Density functional calculations using a nonlocal functional are
performed for NaC60 and Na2C60 in various configurations. These data are used
to construct an empirical atomistic model in order to treat larger sizes in a
statistical and dynamical context. Fluctuating charges are incorporated to
account for charge transfer between sodium and carbon atoms. By performing
systematic global optimization in the size range 1<=n<=30, we find that Na_nC60
is homogeneously coated at small sizes, and that a growing droplet is formed
above n=>8. The separate effects of single ionization and thermalization are
also considered, as well as the changes due to a strong external electric
field. The present results are discussed in the light of various experimental
data.Comment: 17 pages, 10 figure
Upgrading Pathways of Intelligent Manufacturing in China: Transitioning across Technological Paradigms
Intelligent technologies are leading to the next wave of industrial revolution in manufacturing. In developed economies, firms are embracing these advanced technologies following a sequential upgrading strategyâfrom digital manufacturing to smart manufacturing (digital-networked), and then to new-generation intelligent manufacturing paradigms. However, Chinese firms face a different scenario. On the one hand, they have diverse technological bases that vary from low-end electrified machinery to leading-edge digital-network technologies; thus, they may not follow an identical upgrading pathway. On the other hand, Chinese firms aim to rapidly catch up and transition from technology followers to probable frontrunners; thus, the turbulences in the transitioning phase may trigger a precious opportunity for leapfrogging, if Chinese manufacturers can swiftly acquire domain expertise through the adoption of intelligent manufacturing technologies. This study addresses the following question by conducting multiple case studies: Can Chinese firms upgrade intelligent manufacturing through different pathways than the sequential one followed in developed economies? The data sources include semi-structured interviews and archival data. This study finds that Chinese manufacturing firms have a variety of pathways to transition across the three technological paradigms of intelligent manufacturing in non-consecutive ways. This finding implies that Chinese firms may strategize their own upgrading pathways toward intelligent manufacturing according to their capabilities and industrial specifics; furthermore, this finding can be extended to other catching-up economies. This paper provides a strategic roadmap as an explanatory guide to manufacturing firms, policymakers, and investors.This research is supported by the National Natural Science Foundation of China (91646102, L1824039, L1724034, L1624045, and L1524015), the project of Chinaâs Ministry of Education âHumanities and Social Sciences (Engineering and Technology Talent Cultivation)â (16JDGC011), CAE Advisory Project âResearch on the strategy of Manufacturing Power towards 2035â (2019-ZD-9), the National Science and Technology Major Project âHigh-end Numerical Control and Fundamental Manufacturing Equipmentâ (2016ZX04005002), Beijing Natural Science Foundation Project (9182013), the Chinese Academy of Engineeringâs China Knowledge Center for Engineering Sciences an Technology Project (CKCEST-2019-2-13, CKCEST-2018-1-13, CKCEST-2017-1-10, and CKCEST-2015-4-2), the UKâChina Industry Academia Partnership Programme (UK-CIAPP\260), as well as the Volvo-supported Green Economy and Sustainable Development Tsinghua University (20153000181) and Tsinghua Initiative Research Project (2016THZW)
Emission factors from residential combustion appliances burning Portuguese biomass fuels
Smoke from residential wood burning has been identified as a major contributor to air pollution,
motivating detailed emission measurements under controlled conditions. A series of experiments were
performed to compare the emission levels from two types of wood-stoves to those of fireplaces. Eight
types of biomass were burned in the laboratory: wood from seven species of trees grown in the
Portuguese forest (Pinus pinaster, Eucalyptus globulus, Quercus suber, Acacia longifolia, Quercus
faginea, Olea europaea and Quercus ilex rotundifolia) and briquettes produced from forest biomass
waste. Average emission factors were in the ranges 27.5â99.2 g CO kg 1, 552â1660 g CO2 kg 1, 0.66â
1.34 g NO kg 1, and 0.82â4.94 g hydrocarbons kg 1 of biomass burned (dry basis). Average particle
emission factors varied between 1.12 and 20.06 g kg 1 biomass burned (dry basis), with higher burn
rates producing significantly less particle mass per kg wood burned than the low burn rates. Particle
mass emission factors from wood-stoves were lower than those from the fireplace. The average emission
factors for organic and elemental carbon were in the intervals 0.24â10.1 and 0.18â0.68 g kg 1 biomass
burned (dry basis), respectively. The elemental carbon content of particles emitted from the energyefficient
ââchimney typeââ logwood stove was substantially higher than in the conventional cast iron
stove and fireplace, whereas the opposite was observed for the organic carbon fraction. Pinus pinaster,
the only softwood species among all, was the biofuel with the lowest emissions of particles, CO, NO and
hydrocarbons
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