461 research outputs found
The detection, extraction and parameter estimation of extreme-mass-ratio inspirals with deep learning
One of the primary goals of space-borne gravitational wave detectors is to
detect and analyze extreme-mass-ratio inspirals (EMRIs). This endeavor presents
a significant challenge due to the complex and lengthy EMRI signals, further
compounded by their inherently faint nature. In this letter, we introduce a
2-layer Convolutional Neural Network (CNN) approach to detect EMRI signals for
space-borne detectors, achieving a true positive rate (TPR) of 96.9 % at a 1 %
false positive rate (FPR) for signal-to-noise ratio (SNR) from 50 to 100.
Especially, the key intrinsic parameters of EMRIs such as mass and spin of the
supermassive black hole (SMBH) and the initial eccentricity of the orbit can be
inferred directly by employing a VGG network. The mass and spin of the SMBH can
be determined at 99 % and 92 % respectively. This will greatly reduce the
parameter spaces and computing cost for the following Bayesian parameter
estimation. Our model also has a low dependency on the accuracy of the waveform
model. This study underscores the potential of deep learning methods in EMRI
data analysis, enabling the rapid detection of EMRI signals and efficient
parameter estimation .Comment: 6 pages, 5 figure
Detecting extreme-mass-ratio inspirals for space-borne detectors with deep learning
One of the primary objectives for space-borne gravitational wave detectors is
the detection of extreme-mass-ratio inspirals (EMRIs). This undertaking poses a
substantial challenge because of the complex and long EMRI signals, further
complicated by their inherently faint signal. In this research, we introduce a
2-layer Convolutional Neural Network (CNN) approach to detect EMRI signals for
space-borne detectors. Our method employs the Q-transform for data
preprocessing, effectively preserving EMRI signal characteristics while
minimizing data size. By harnessing the robust capabilities of CNNs, we can
reliably distinguish EMRI signals from noise, particularly when the
signal-to-noise~(SNR) ratio reaches 50, a benchmark considered a ``golden''
EMRI. At the meantime, we incorporate time-delay interferometry (TDI) to ensure
practical utility. We assess our model's performance using a 0.5-year dataset,
achieving a true positive rate~(TPR) of 94.2\% at a 1\% false positive
rate~(FPR) across various signal-to-noise ratio form 50-100, with 91\% TPR and
1\% FPR at an SNR of 50. This study underscores the promise of incorporating
deep learning methods to advance EMRI data analysis, potentially leading to
rapid EMRI signal detection.Comment: 12 pages, 8 figures, 2 table
Supporting nickel on vanadium nitride for comparable hydrogen evolution performance to platinum in alkaline solution
The hydrogen evolution reaction (HER) is an effective means to producing hydrogen from electrolytic water splitting. However the best-performing catalysts use expensive Pt-group metals. Cheaper non-precious metal alternatives have shown low activity as their mechanism of H-2 formation (Volmer-Heyrovsky) leads to high overpotentials. Here, we report an outstanding HER catalyst (Ni/VN) highly dispersed nickel supported on vanadium nitride that matches the turnover frequency of the platinum on carbon (Pt/C) benchmark material. It is more durable than Pt/C in alkaline solution. Ni/VN follows the low-overpotential (Volmer-Tafel) mechanism of H-2 formation, with a 43 mV overpotential at a current density of 10 mA cm(-2). This value is even below that of Pt/C (57 mV). The support of VN enhances the dispersion of nickel, weakens the surface oxidation, decreases the hydrogen binding energy, and therefore significantly improves the HER catalysis. This result removes one of the major barriers for scalability of electrolytic water-splitting by demonstrating that nitride-based materials can match and even surpass the efficiency and durability of precious metal catalysts
Surface Functionalized Sensors for Humidity-Independent Gas Detection
Semiconducting metal oxides (SMOXs) are used widely for gas sensors. However, the effect of ambient humidity on the baseline and sensitivity of the chemiresistors is still a largely unsolved problem, reducing sensor accuracy and causing complications for sensor calibrations. Presented here is a general strategy to overcome water-sensitivity issues by coating SMOXs with a hydrophobic polymer separated by a metal-organic framework (MOF) layer that preserves the SMOX surface and serves a gas-selective function. Sensor devices using these nanoparticles display near-constant responses even when humidity is varied across a wide range [0-90 % relative humidity (RH)]. Furthermore, the sensor delivers notable performance below 20 % RH whereas other water-resistance strategies typically fail. Selectivity enhancement and humidity-independent sensitivity are concomitantly achieved using this approach. The reported tandem coating strategy is expected to be relevant for a wide range of SMOXs, leading to a new generation of gas sensors with excellent humidity-resistant performance
DISCO: Achieving Low Latency and High Reliability in Scheduling of Graph-Structured Tasks over Mobile Vehicular Cloud
To effectively process data across a fleet of dynamic and distributed
vehicles, it is crucial to implement resource provisioning techniques that
provide reliable, cost-effective, and real-time computing services. This
article explores resource provisioning for computation-intensive tasks over
mobile vehicular clouds (MVCs). We use undirected weighted graphs (UWGs) to
model both the execution of tasks and communication patterns among vehicles in
a MVC. We then study low-latency and reliable scheduling of UWG asks through a
novel methodology named double-plan-promoted isomorphic subgraph search and
optimization (DISCO). In DISCO, two complementary plans are envisioned to
ensure effective task completion: Plan A and Plan B.Plan A analyzes the past
data to create an optimal mapping () between tasks and the MVC in
advance to the practical task scheduling. Plan B serves as a dependable backup,
designed to find a feasible mapping () in case fails during
task scheduling due to unpredictable nature of the network.We delve into into
DISCO's procedure and key factors that contribute to its success. Additionally,
we provide a case study that includes comprehensive comparisons to demonstrate
DISCO's exceptional performance in regards to time efficiency and overhead. We
further discuss a series of open directions for future research
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