130 research outputs found
Multi-level Gated Bayesian Recurrent Neural Network for State Estimation
The optimality of Bayesian filtering relies on the completeness of prior
models, while deep learning holds a distinct advantage in learning models from
offline data. Nevertheless, the current fusion of these two methodologies
remains largely ad hoc, lacking a theoretical foundation. This paper presents a
novel solution, namely a multi-level gated Bayesian recurrent neural network
specifically designed to state estimation under model mismatches. Firstly, we
transform the non-Markov state-space model into an equivalent first-order
Markov model with memory. It is a generalized transformation that overcomes the
limitations of the first-order Markov property and enables recursive filtering.
Secondly, by deriving a data-assisted joint state-memory-mismatch Bayesian
filtering, we design a Bayesian multi-level gated framework that includes a
memory update gate for capturing the temporal regularities in state evolution,
a state prediction gate with the evolution mismatch compensation, and a state
update gate with the observation mismatch compensation. The Gaussian
approximation implementation of the filtering process within the gated
framework is derived, taking into account the computational efficiency.
Finally, the corresponding internal neural network structures and end-to-end
training methods are designed. The Bayesian filtering theory enhances the
interpretability of the proposed gated network, enabling the effective
integration of offline data and prior models within functionally explicit gated
units. In comprehensive experiments, including simulations and real-world
datasets, the proposed gated network demonstrates superior estimation
performance compared to benchmark filters and state-of-the-art deep learning
filtering methods
MDDL: A Framework for Reinforcement Learning-based Position Allocation in Multi-Channel Feed
Nowadays, the mainstream approach in position allocation system is to utilize
a reinforcement learning model to allocate appropriate locations for items in
various channels and then mix them into the feed. There are two types of data
employed to train reinforcement learning (RL) model for position allocation,
named strategy data and random data. Strategy data is collected from the
current online model, it suffers from an imbalanced distribution of
state-action pairs, resulting in severe overestimation problems during
training. On the other hand, random data offers a more uniform distribution of
state-action pairs, but is challenging to obtain in industrial scenarios as it
could negatively impact platform revenue and user experience due to random
exploration. As the two types of data have different distributions, designing
an effective strategy to leverage both types of data to enhance the efficacy of
the RL model training has become a highly challenging problem. In this study,
we propose a framework named Multi-Distribution Data Learning (MDDL) to address
the challenge of effectively utilizing both strategy and random data for
training RL models on mixed multi-distribution data. Specifically, MDDL
incorporates a novel imitation learning signal to mitigate overestimation
problems in strategy data and maximizes the RL signal for random data to
facilitate effective learning. In our experiments, we evaluated the proposed
MDDL framework in a real-world position allocation system and demonstrated its
superior performance compared to the previous baseline. MDDL has been fully
deployed on the Meituan food delivery platform and currently serves over 300
million users.Comment: 4 pages, 2 figures, accepted by SIGIR 202
Laminated Ti-Al composites: Processing, structure and strength
Laminated Ti-Al composite sheets with different layer thickness ratios have been fabricated through hot pressing followed by multi-pass hot rolling at 500 °C.The laminated sheets show strong bonding with intermetallic interface layers of nanoscale thickness between the layers of Ti and Al. The mechanical properties of the composites with different volume fractions of Al from 10% to 67% show a good combination of strength and ductility. A constraint strain in the hot-rolled laminated structure between the hard and soft phases introduces an elastic-plastic deformation stage, which becomes more pronounced as the volume fraction of Al decreases. Moreover, the thin intermetallic interface layer may also contribute to the strength of the composites, and this effect increases with increasing volume fraction of the interface layer
The performance of large-pitch AC-LGAD with different N+ dose
AC-Coupled LGAD (AC-LGAD) is a new 4D detector developed based on the Low
Gain Avalanche Diode (LGAD) technology, which can accurately measure the time
and spatial information of particles. Institute of High Energy Physics (IHEP)
designed a large-size AC-LGAD with a pitch of 2000 {\mu}m and AC pad of 1000
{\mu}m, and explored the effect of N+ layer dose on the spatial resolution and
time resolution. The spatial resolution varied from 32.7 {\mu}m to 15.1 {\mu}m
depending on N+ dose. The time resolution does not change significantly at
different N+ doses, which is about 15-17 ps. AC-LGAD with a low N+ dose has a
large attenuation factor and better spatial resolution. Large signal
attenuation factor and low noise level are beneficial to improve the spatial
resolution of the AC-LGAD sensor
Use of Praziquantel as an Adjuvant Enhances Protection and Tc-17 Responses to Killed H5N1 Virus Vaccine in Mice
BACKGROUND: H5N1 is a highly pathogenic influenza A virus, which can cause severe illness or even death in humans. Although the widely used killed vaccines are able to provide some protection against infection via neutralizing antibodies, cytotoxic T-lymphocyte responses that are thought to eradicate viral infections are lacking. METHODOLOGY/PRINCIPAL FINDINGS: Aiming to promote cytotoxic responses against H5N1 infection, we extended our previous finding that praziquantel (PZQ) can act as an adjuvant to induce IL-17-producing CD8(+) T cells (Tc17). We found that a single immunization of 57BL/6 mice with killed viral vaccine plus PZQ induced antigen-specific Tc17 cells, some of which also secreted IFN-γ. The induced Tc17 had cytolytic activities. Induction of these cells was impaired in CD8 knockout (KO) or IFN-γ KO mice, and was even lower in IL-17 KO mice. Importantly, the inoculation of killed vaccine with PZQ significantly reduced virus loads in the lung tissues and prolonged survival. Protection against H5N1 virus infection was obtained by adoptively transferring PZQ-primed wild type CD8(+) T cells and this was more effective than transfer of activated IFN-γ KO or IL-17 KO CD8(+) T cells. CONCLUSIONS/SIGNIFICANCE: Our results demonstrated that adding PZQ to killed H5N1 vaccine could promote broad Tc17-mediated cytotoxic T lymphocyte activity, resulting in improved control of highly pathogenic avian influenza virus infection
Potential of Core-Collapse Supernova Neutrino Detection at JUNO
JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve
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