28,605 research outputs found
Solar concentrator
An improved solar concentrator is characterized by a number of elongated supporting members arranged in substantial horizontal parallelism with the axis and intersecting a common curve. A tensioned sheet of flexible reflective material is disposed in engaging relation with the supporting members in order to impart to the tensioned sheet a catenary configuration
The role of Guanxi on Chinese leadership innovation:the pilot study on the electric motor sector
This research aims to examine the existence and nature of complex business-social relationships in the Chinese context (Guanxi) and evaluate how these relationships influence the behaviors of managers in State-owned Chinese engineering firms. Research on Guanxi is comprehensive though little work investigates internal influences and how internal relationships may mirror or replicate external Guanxi. This study uses a snowball sample of 66 senior managers across the key functional disciplines in typical large Chinese firms and explores how often strategic level problems in the firm are solved through relationships outside, inside or between the companies. Do Guanxi networks penetrate the organization itself and are there relationships that are unique to internal networks? The research finds that problem solving at strategic levels are often through internal and external networks, rather than internal management structures, but also that different problems complexities typically demonstrate unique problem-solving networks. The research identifies three different forms that these relationships take: Internal, inter-firm and hybrid relationship modes. Implications for this work suggest problem solving in Chinese firms is enhanced through cooperation and mutual respect, and likely to be inhibited by traditional Western approaches to management
Reversible signal transmission in an active mechanical metamaterial
Mechanical metamaterials are designed to enable unique functionalities, but
are typically limited by an initial energy state and require an independent
energy input to function repeatedly. Our study introduces a theoretical active
mechanical metamaterial that incorporates a biological reaction mechanism to
overcome this key limitation of passive metamaterials. Our material allows for
reversible mechanical signal transmission, where energy is reintroduced by the
biologically motivated reaction mechanism. By analysing a coarse grained
continuous analogue of the discrete model, we find that signals can be
propagated through the material by a travelling wave. Analysis of the continuum
model provides the region of the parameter space that allows signal
transmission, and reveals similarities with the well-known FitzHugh-Nagumo
system. We also find explicit formulae that approximate the effect of the
timescale of the reaction mechanism on the signal transmission speed, which is
essential for controlling the material.Comment: 20 pages, 7 figure
Solar Modulation of the Galactic Helium Spectrum Above 30 Mev Per Nucleon
Time measurements of differential energy spectra and flux of primary helium nuclei by use of charged particle telescope
Acceleration of particles in the earth's shock transition region and beyond
Acceleration of particles in earth shock transition region and beyon
Diffuse gamma radiation
An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy
Two quantum Simpson's paradoxes
The so-called Simpson's "paradox", or Yule-Simpson (YS) effect, occurs in
classical statistics when the correlations that are present among different
sets of samples are reversed if the sets are combined together, thus ignoring
one or more lurking variables. Here we illustrate the occurrence of two
analogue effects in quantum measurements. The first, which we term
quantum-classical YS effect, may occur with quantum limited measurements and
with lurking variables coming from the mixing of states, whereas the second,
here referred to as quantum-quantum YS effect, may take place when coherent
superpositions of quantum states are allowed. By analyzing quantum measurements
on low dimensional systems (qubits and qutrits), we show that the two effects
may occur independently, and that the quantum-quantum YS effect is more likely
to occur than the corresponding quantum-classical one. We also found that there
exist classes of superposition states for which the quantum-classical YS effect
cannot occur for any measurement and, at the same time, the quantum-quantum YS
effect takes place in a consistent fraction of the possible measurement
settings. The occurrence of the effect in the presence of partial coherence is
discussed as well as its possible implications for quantum hypothesis testing.Comment: published versio
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