2,655 research outputs found
Space- and Computationally-Efficient Set Reconciliation via Parity Bitmap Sketch (PBS)
Set reconciliation is a fundamental algorithmic problem that arises in many
networking, system, and database applications. In this problem, two large sets
A and B of objects (bitcoins, files, records, etc.) are stored respectively at
two different network-connected hosts, which we name Alice and Bob
respectively. Alice and Bob communicate with each other to learn ,
the difference between A and B, and as a result the reconciled set .
Current set reconciliation schemes are based on either Invertible Bloom
Filters (IBF) or Error-Correction Codes (ECC). The former has a low
computational complexity of O(d), where d is the cardinality of ,
but has a high communication overhead that is several times larger than the
theoretical minimum. The latter has a low communication overhead close to the
theoretical minimum, but has a much higher computational complexity of
. In this work, we propose Parity Bitmap Sketch (PBS), an ECC- based
set reconciliation scheme that gets the better of both worlds: PBS has both a
low computational complexity of O(d) just like IBF-based solutions and a low
communication overhead of roughly twice the theoretical minimum. A separate
contribution of this work is a novel rigorous analytical framework that can be
used for the precise calculation of various performance metrics and for the
near-optimal parameter tuning of PBS
Testing and Data Reduction of the Chinese Small Telescope Array (CSTAR) for Dome A, Antarctica
The Chinese Small Telescope ARray (hereinafter CSTAR) is the first Chinese
astronomical instrument on the Antarctic ice cap. The low temperature and low
pressure testing of the data acquisition system was carried out in a laboratory
refrigerator and on the 4500m Pamirs high plateau, respectively. The results
from the final four nights of test observations demonstrated that CSTAR was
ready for operation at Dome A, Antarctica. In this paper we present a
description of CSTAR and the performance derived from the test observations.Comment: Accepted Research in Astronomy and Astrophysics (RAA) 1 Latex file
and 20 figure
Colorful Hydrophobic Poly(Vinyl Butyral)/Cationic Dye Fibrous Membranes via a Colored Solution Electrospinning Process
Supplementary Materials. (DOCX 3474 kb
Optimized hydrophobic magnetic nanoparticles stabilized pickering emulsion for enhanced oil recovery in complex porous media of reservoir
With an extensive application of flooding technologies in oil recovery, traditional emulsion flooding has seen many limits due to its poor stability and easy demulsification. Pursuing a new robust emulsion plays a fundamental role in developing highly effective emulsion flooding technology. In this work, a novel Pickering emulsion with special magnetic nanoparticles Fe3O4@PDA@Si was designed and prepared. To disclose the flooding mechanism from magnetic nanoparticles, the physico-chemical characterization of Fe3O4@PDA@Si was systematically examined. Meanwhile, the flooding property of the constructed Pickering emulsion was evaluated on the basis of certain downhole conditions. The results showed that the synthesis of Fe3O4@PDA@Si nanoparticles was found to have a hydrophobic core-shell structure with a diameter of 30 nm. Pickering emulsions based on Fe3O4@PDA@Si nanoparticles at an oil-to-water ratio of 5:5, 50°C, the water separation rate was only 6% and the droplet diameter of the emulsion was approximately 15 μm in the ultra-depth-of-field microscope image. This demonstrates the excellent stability of Pickering emulsions and improves the problem of easy demulsification. We further discussed the oil displacement mechanism and enhanced oil recovery effect of this type of emulsion. The microscopic flooding experiment demonstrated that profile control of the Pickering emulsion played a more important role in enhanced recovery than emulsification denudation, with the emulsion system increasing oil recovery by 10.18% in the micro model. Core flooding experiments have established that the incremental oil recovery of the Pickering emulsion increases with decreasing core permeability, from 12.36% to 17.39% as permeability drops from 834.86 to 219.34 × 10−3 μm2. This new Pickering emulsion flooding system stabilized by Fe3O4@PDA@Si nanoparticles offers an option for enhanced oil recovery (EOR)
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