211 research outputs found
Form, space and spiritual enrichment : a Chinese Community Center in Des Moines
The purpose of this project is to express how architectural space can enrich people\u27s lives and lift their spirits. More and more Chinese students study in the United States. In some cases, they feel lonely and isolated in such an unfamiliar situation. Psychological problems often develop when people are working under extreme pressure and experiencing spiritual loneliness. These problems are more serious in small towns in the Midwestern region of the United States. To accommodate the social and psychological needs of the Chinese community in Iowa, a Chinese Community Center was designed in Des Moines. The author study the psychological problems of Chinese students and scholars in the United States and then design traditional Chinese spaces to provide comfort and to help them enrich their spirits. The design is based on traditional Chinese architectural concepts and modern form. The center creates harmony between architecture and the environment; it will also be an interesting building to compare to and incorporate with the Des Moines Art Center
Droplet routing for digital microfluidic biochips based on microelectrode dot array architecture
A digital microfluidic biochip (DMFB) is a device that digitizes fluidic samples into tiny droplets and operates chemical processes on a single chip. Movement control of droplets can be realized by using electrowetting-on-dielectric (EWOD) technology. DMFBs have high configurability, high sensitivity, low cost and reduced human error as well as a promising future in the applications of point-of-care medical diagnostic, and DNA sequencing. As the demands of scalability, configurability and portability increase, a new DMFB architecture called Microelectrode Dot Array (MEDA) has been introduced recently to allow configurable electrodes shape and more precise control of droplets.
The objective of this work is to investigate a routing algorithm which can not only handle the routing problem for traditional DMFBs, but also be able to route different sizes of droplets and incorporate diagonal movements for MEDA. The proposed droplet routing algorithm is based on 3D-A* search algorithm. The simulation results show that the proposed algorithm can reduce the maximum latest arrival time, average latest arrival time and total number of used cells. By enabling channel-based routing in MEDA, the equivalent total number of used cells can be significantly reduced. Compared to all existing algorithms, the proposed algorithm can achieve so far the least average latest arrival time
Transient dynamics of a one-dimensional Holstein polaron under the influence of an external electric field
Following the Dirac-Frenkel time-dependent variational principle, transient
dynamics of a one-dimensional Holstein polaron with diagonal and off-diagonal
exciton-phonon coupling in an external electric field is studied by employing
the multi-D {\it Ansatz}, also known as a superposition of the usual
Davydov D trial states. Resultant polaron dynamics has significantly
enhanced accuracy, and is in perfect agreement with that derived from the
hierarchy equations of motion method. Starting from an initial broad wave
packet, the exciton undergoes typical Bloch oscillations. Adding weak
exciton-phonon coupling leads to a broadened exciton wave packet and a reduced
current amplitude. Using a narrow wave packet as the initial state, the bare
exciton oscillates in a symmetric breathing mode, but the symmetry is easily
broken by weak coupling to phonons, resulting in a non-zero exciton current.
For both scenarios, temporal periodicity is unchanged by exciton-phonon
coupling. In particular, at variance with the case of an infinite linear chain,
no steady state is found in a finite-sized ring within the anti-adiabatic
regime. For strong diagonal coupling, the multi- {\it Anstaz} is found
to be highly accurate, and the phonon confinement gives rise to exciton
localization and decay of the Bloch oscillations
Optimal Walking of an Underactuated Planar Biped with Segmented Torso
Recently, underactuated bipeds with pointed feet have been studied to achieve dynamic and energy efficient robot walking patterns. However, these studies usually simplify a robot torso as one link, which is different from a human torsos containing 33 vertebrae. In this paper, therefore, we study the optimal walking of a 6-link planar biped with a segmented torso derived from its 5-link counterpart while ensuring that two models are equivalent when the additional torso joint is locked. For the walking, we suppose that each step is composed of a single support phase and an instantaneous double support phase, and two phases are connected by a plastic impact mapping. In addition, the controlled outputs named symmetry outputs capable of generating exponentially stable orbits using hybrid zero dynamics, are adopted to improve physical interpretation. The desired outputs are parameterized by B´ezier functions, with 5-link robot having 16 parameters to optimize and 6-link robot having 19 parameters. According to our energy criterion, the segmented torso structure may reduce energy consumption up to 8% in bipedal walking, and the maximum energy saving is achieved at high walking speeds, while leaving the criteria at low walking speeds remain similar for both robots.China CSC LCF
The observation of diffraction phases in matter wave scattering
We study the diffraction phase of different orders via the Dyson expansion
series, for ultracold atomic gases scattered by a standing-wave pulse. As these
diffraction phases are not observable in a single pulse scattering process, a
temporal Talbot-Lau interferometer consisting of two standing-wave pulses is
demonstrated experimentally with a Bose-Einstein condensate to explore this
physical effect. The role of the diffraction phases is clearly shown by the
second standing-wave pulse in the relative population of different momentum
states. Our experiments demonstrate obvious effects beyond the Raman-Nath
method, while agree well with our theory by including the diffraction phases.
In particular, the observed asymmetry in the dependence of the relative
population on the interval between two standing-wave pulses reflects the
diffraction phase differences. The role of interatomic interaction in the
Talbot-Lau interferometer is also discussed.Comment: 7 pages, 3 figures, accepted by Phys. Rev.
Asymmetric superradiant scattering and abnormal mode amplification induced by atomic density distortion
The superradiant Rayleigh scattering using a pump laser incident along the
short axis of a Bose-Einstein condensate with a density distortion is studied,
where the distortion is formed by shocking the condensate utilizing the
residual magnetic force after the switching-off of the trapping potential. We
find that very small variation of the atomic density distribution would induce
remarkable asymmetrically populated scattering modes by the matter-wave
superradiance with long time pulse. The optical field in the diluter region of
the atomic cloud is more greatly amplified, which is not an ordinary mode
amplification with the previous cognition. Our numerical simulations with the
density envelop distortion are consistent with the experimental results. This
supplies a useful method to reflect the geometric symmetries of the atomic
density profile by the superradiance scattering.Comment: 7pages,4 figures, Optical Express 21,(2013)1437
Manipulating the momentum state of a condensate by sequences of standing wave pulses
We analyze the effects of sequences of standing wave pulses on a
Bose-Einstein condensate (BEC). Experimental observations are in good agreement
with a numerical simulation based on the band structure theory in the optical
lattice. We also demonstrate that a coherent control method based on such
sequences of pulses is very efficient for experimentally designing specific
momentum states.Comment: 6 pages; 5 figures; submitted to PR
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