6,501 research outputs found
Comparative study of different approaches to solve batch process scheduling and optimisation problems
Effective approaches are important to batch process scheduling problems, especially those with complex constraints. However, most research focus on improving optimisation techniques, and those concentrate on comparing their difference are inadequate. This study develops an optimisation model of batch process scheduling problems with complex constraints and investigates the performance of different optimisation techniques, such as Genetic Algorithm (GA) and Constraint Programming (CP). It finds that CP has a better capacity to handle batch process problems with complex constraints but it costs longer time
The dream alchemy
I strive to record and express moments from within my dreams, in order to obviate their elusiveness. I am a spectator in my dreams and sometimes find myself seized by violent and terrific events. These dreams from my subconscious guide me to the part of myself which I do not always recognize in my consciousness. I wish to know where these contents come from, why I have these dreams, or if these dreams are referencing narratives from my personal experience. The contents of these dreams, as well as the act of reflecting on them, call out my shadow––the unconscious aspect of my personality which I tend to repress. As a jeweler, I bring this darkness back to reality and document it through my work. By carefully constructing my “silver drawings,” I transcribe the shadow into something tangible. Now I can always be mindful of my shadow
Space qualified nanosatellite electronics platform for photon pair experiments
We report the design and implementation of a complete electronics platform
for conducting a quantum optics experiment that will be operated on board a 1U
CubeSat (a 10 x 10 x 10 cm satellite). The quantum optics experiment is
designed to produce polarization-entangled photon pairs using non-linear
optical crystals and requires opto-electronic components such as a pump laser,
single photon detectors and liquid crystal based polarization rotators in
addition to passive optical elements. The platform provides mechanical support
for the optical assembly. It also communicates autonomously with the host
satellite to provide experiment data for transmission to a ground station. A
limited number of commands can be transmitted from ground to the platform
enabling it to switch experimental modes. This platform requires less than 1.5W
for all operations, and is space qualified. The implementation of this
electronics platform is a major step on the road to operating quantum
communication experiments using nanosatellites.Comment: 6 pages, 11 figure
Silicon avalanche photodiode operation and lifetime analysis for small satellites
Silicon avalanche photodiodes (APDs) are sensitive to operating temperature
fluctuations and are also susceptible to radiation flux expected in
satellite-based quantum experiments. We introduce a low power voltage adjusting
mechanism to overcome the effects of in-orbit temperature fluctuations. We also
present data on the performance of Si APDs after irradiation (gamma-ray and
proton beam). Combined with an analysis of expected orbital irradiation, we
propose that a Si APD in a 400 km equatorial orbit may operate beyond the
lifetime of the satellite.Comment: 9 pages, 7 figures, accepted by Optics Expres
Spin superconductor in ferromagnetic graphene
We show a spin superconductor (SSC) in ferromagnetic graphene as the
counterpart to the charge superconductor, in which a spin-polarized
electron-hole pair plays the role of the spin `Cooper pair' with
a neutral charge. We present a BCS-type theory for the SSC. With the
`London-type equations' of the super-spin-current density, we show the
existence of an electric `Meissner effect' against a spatial varying electric
field. We further study a SSC/normal conductor/SSC junction and predict a
spin-current Josephson effect.Comment: 6 pages, 4 figure
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