4,834 research outputs found
A Novel Apex-Time Network for Cross-Dataset Micro-Expression Recognition
The automatic recognition of micro-expression has been boosted ever since the
successful introduction of deep learning approaches. As researchers working on
such topics are moving to learn from the nature of micro-expression, the
practice of using deep learning techniques has evolved from processing the
entire video clip of micro-expression to the recognition on apex frame. Using
the apex frame is able to get rid of redundant video frames, but the relevant
temporal evidence of micro-expression would be thereby left out. This paper
proposes a novel Apex-Time Network (ATNet) to recognize micro-expression based
on spatial information from the apex frame as well as on temporal information
from the respective-adjacent frames. Through extensive experiments on three
benchmarks, we demonstrate the improvement achieved by learning such temporal
information. Specially, the model with such temporal information is more robust
in cross-dataset validations.Comment: 6 pages, 3 figures, 3 tables, code available, accepted in ACII 201
Geometric vs. Dynamical Gates in Quantum Computing Implementations Using Zeeman and Heisenberg Hamiltonians
Quantum computing in terms of geometric phases, i.e. Berry or
Aharonov-Anandan phases, is fault-tolerant to a certain degree. We examine its
implementation based on Zeeman coupling with a rotating field and isotropic
Heisenberg interaction, which describe NMR and can also be realized in quantum
dots and cold atoms. Using a novel physical representation of the qubit basis
states, we construct and Hadamard gates based on Berry and
Aharonov-Anandan phases. For two interacting qubits in a rotating field, we
find that it is always impossible to construct a two-qubit gate based on Berry
phases, or based on Aharonov-Anandan phases when the gyromagnetic ratios of the
two qubits are equal. In implementing a universal set of quantum gates, one may
combine geometric and Hadamard gates and dynamical
gate.Comment: published version, 5 page
Knowledge-Aware Federated Active Learning with Non-IID Data
Federated learning enables multiple decentralized clients to learn
collaboratively without sharing the local training data. However, the expensive
annotation cost to acquire data labels on local clients remains an obstacle in
utilizing local data. In this paper, we propose a federated active learning
paradigm to efficiently learn a global model with limited annotation budget
while protecting data privacy in a decentralized learning way. The main
challenge faced by federated active learning is the mismatch between the active
sampling goal of the global model on the server and that of the asynchronous
local clients. This becomes even more significant when data is distributed
non-IID across local clients. To address the aforementioned challenge, we
propose Knowledge-Aware Federated Active Learning (KAFAL), which consists of
Knowledge-Specialized Active Sampling (KSAS) and Knowledge-Compensatory
Federated Update (KCFU). KSAS is a novel active sampling method tailored for
the federated active learning problem. It deals with the mismatch challenge by
sampling actively based on the discrepancies between local and global models.
KSAS intensifies specialized knowledge in local clients, ensuring the sampled
data to be informative for both the local clients and the global model. KCFU,
in the meantime, deals with the client heterogeneity caused by limited data and
non-IID data distributions. It compensates for each client's ability in weak
classes by the assistance of the global model. Extensive experiments and
analyses are conducted to show the superiority of KSAS over the
state-of-the-art active learning methods and the efficiency of KCFU under the
federated active learning framework.Comment: 14 pages, 12 figure
4-[(2′-Cyanobiphenyl-4-yl)methyl]morpholin-4-ium hexafluoridophosphate
In the cation of the title compound, C18H19N2O+·PF6
−, the morpholine ring adopts the usual chair conformation and the dihedral angle between the benzene rings is 67.55 (11)°. The F atoms of the anion are disordered over two orientations with a refined occupancy ratio of 0.65 (2):0.35 (2). In the crystal, intermolecular N—H⋯N hydrogen bonds link the cations into chains parallel to the c axis. The crystal packing is further enforced by interionic C—H⋯F hydrogen bonds
How Re-sampling Helps for Long-Tail Learning?
Long-tail learning has received significant attention in recent years due to
the challenge it poses with extremely imbalanced datasets. In these datasets,
only a few classes (known as the head classes) have an adequate number of
training samples, while the rest of the classes (known as the tail classes) are
infrequent in the training data. Re-sampling is a classical and widely used
approach for addressing class imbalance issues. Unfortunately, recent studies
claim that re-sampling brings negligible performance improvements in modern
long-tail learning tasks. This paper aims to investigate this phenomenon
systematically. Our research shows that re-sampling can considerably improve
generalization when the training images do not contain semantically irrelevant
contexts. In other scenarios, however, it can learn unexpected spurious
correlations between irrelevant contexts and target labels. We design
experiments on two homogeneous datasets, one containing irrelevant context and
the other not, to confirm our findings. To prevent the learning of spurious
correlations, we propose a new context shift augmentation module that generates
diverse training images for the tail class by maintaining a context bank
extracted from the head-class images. Experiments demonstrate that our proposed
module can boost the generalization and outperform other approaches, including
class-balanced re-sampling, decoupled classifier re-training, and data
augmentation methods. The source code is available at
https://www.lamda.nju.edu.cn/code_CSA.ashx.Comment: Accepted by NeurIPS 202
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