426 research outputs found
Fast B-spline Curve Fitting by L-BFGS
We propose a novel method for fitting planar B-spline curves to unorganized
data points. In traditional methods, optimization of control points and foot
points are performed in two very time-consuming steps in each iteration: 1)
control points are updated by setting up and solving a linear system of
equations; and 2) foot points are computed by projecting each data point onto a
B-spline curve. Our method uses the L-BFGS optimization method to optimize
control points and foot points simultaneously and therefore it does not need to
perform either matrix computation or foot point projection in every iteration.
As a result, our method is much faster than existing methods
Quantum Discord for Investigating Quantum Correlations without Entanglement in Solids
Quantum systems unfold diversified correlations which have no classical
counterparts. These quantum correlations have various different facets. Quantum
entanglement, as the most well known measure of quantum correlations, plays
essential roles in quantum information processing. However, it has recently
been pointed out that quantum entanglement cannot describe all the
nonclassicality in the correlations. Thus the study of quantum correlations in
separable states attracts widely attentions. Herein, we experimentally
investigate the quantum correlations of separable thermal states in terms of
quantum discord. The sudden change of quantum discord is observed, which
captures ambiguously the critical point associated with the behavior of
Hamiltonian. Our results display the potential applications of quantum
correlations in studying the fundamental properties of quantum system, such as
quantum criticality of non-zero temperature.Comment: 4 pages, 4 figure
Culture Fever: Utopianism and Pragmatism in Chinese Intellectuals\u27 Search for Modernization
Situating the 1980s Cultural Fever in a global westernization context and as one of the three major waves of the Chinese intellectual movement in the last two centuries, this paper attempts to analyze the complexities and nuances of the cultural reckoning process in the mid-1980s by examining how such process is manifested in academia, a magazine called Reading, a TV-series documentary titled River Elegy (Heshang), and movie Red Sorghum (Honggaoliang). Although different in their schools of affiliation, areas of expertise, and intended audience, in hope of a shared utopian future, Chinese intellectuals in the 1980s carried out their self-proclaimed duty to contribute to the transformation by producing different theoretical reformulations of national identity
Observation of strong attenuation within the photonic band gap of multiconnected networks
We theoretically and experimentally study a photonic band gap (PBG) material
made of coaxial cables. The coaxial cables are waveguides for the
electromagnetic waves and provide paths for direct wave interference within the
material. Using multiconnected coaxial cables to form a unit cell, we realize
PBGs via (i) direct interference between the waveguides within each cell and
(ii) scattering among different cells. We systematically investigate the
transmission of EM waves in our PBG materials and discuss the mechanism of band
gap formation. We observe experimentally for the first time the wide band gap
with strong attenuation caused by direct destructive interference
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