71 research outputs found
Genetic Algorithms with Neural Cost Predictor for Solving Hierarchical Vehicle Routing Problems
When vehicle routing decisions are intertwined with higher-level decisions,
the resulting optimization problems pose significant challenges for
computation. Examples are the multi-depot vehicle routing problem (MDVRP),
where customers are assigned to depots before delivery, and the capacitated
location routing problem (CLRP), where the locations of depots should be
determined first. A simple and straightforward approach for such hierarchical
problems would be to separate the higher-level decisions from the complicated
vehicle routing decisions. For each higher-level decision candidate, we may
evaluate the underlying vehicle routing problems to assess the candidate. As
this approach requires solving vehicle routing problems multiple times, it has
been regarded as impractical in most cases. We propose a novel
deep-learning-based approach called Genetic Algorithm with Neural Cost
Predictor (GANCP) to tackle the challenge and simplify algorithm developments.
For each higher-level decision candidate, we predict the objective function
values of the underlying vehicle routing problems using a pre-trained graph
neural network without actually solving the routing problems. In particular,
our proposed neural network learns the objective values of the HGS-CVRP
open-source package that solves capacitated vehicle routing problems. Our
numerical experiments show that this simplified approach is effective and
efficient in generating high-quality solutions for both MDVRP and CLRP and has
the potential to expedite algorithm developments for complicated hierarchical
problems. We provide computational results evaluated in the standard benchmark
instances used in the literature
Layer-wise Auto-Weighting for Non-Stationary Test-Time Adaptation
Given the inevitability of domain shifts during inference in real-world
applications, test-time adaptation (TTA) is essential for model adaptation
after deployment. However, the real-world scenario of continuously changing
target distributions presents challenges including catastrophic forgetting and
error accumulation. Existing TTA methods for non-stationary domain shifts,
while effective, incur excessive computational load, making them impractical
for on-device settings. In this paper, we introduce a layer-wise auto-weighting
algorithm for continual and gradual TTA that autonomously identifies layers for
preservation or concentrated adaptation. By leveraging the Fisher Information
Matrix (FIM), we first design the learning weight to selectively focus on
layers associated with log-likelihood changes while preserving unrelated ones.
Then, we further propose an exponential min-max scaler to make certain layers
nearly frozen while mitigating outliers. This minimizes forgetting and error
accumulation, leading to efficient adaptation to non-stationary target
distribution. Experiments on CIFAR-10C, CIFAR-100C, and ImageNet-C show our
method outperforms conventional continual and gradual TTA approaches while
significantly reducing computational load, highlighting the importance of
FIM-based learning weight in adapting to continuously or gradually shifting
target domains.Comment: WACV 202
Introducing Competition to Boost the Transferability of Targeted Adversarial Examples through Clean Feature Mixup
Deep neural networks are widely known to be susceptible to adversarial
examples, which can cause incorrect predictions through subtle input
modifications. These adversarial examples tend to be transferable between
models, but targeted attacks still have lower attack success rates due to
significant variations in decision boundaries. To enhance the transferability
of targeted adversarial examples, we propose introducing competition into the
optimization process. Our idea is to craft adversarial perturbations in the
presence of two new types of competitor noises: adversarial perturbations
towards different target classes and friendly perturbations towards the correct
class. With these competitors, even if an adversarial example deceives a
network to extract specific features leading to the target class, this
disturbance can be suppressed by other competitors. Therefore, within this
competition, adversarial examples should take different attack strategies by
leveraging more diverse features to overwhelm their interference, leading to
improving their transferability to different models. Considering the
computational complexity, we efficiently simulate various interference from
these two types of competitors in feature space by randomly mixing up stored
clean features in the model inference and named this method Clean Feature Mixup
(CFM). Our extensive experimental results on the ImageNet-Compatible and
CIFAR-10 datasets show that the proposed method outperforms the existing
baselines with a clear margin. Our code is available at
https://github.com/dreamflake/CFM.Comment: CVPR 2023 camera-read
Scandium Doping Effect on a Layered Perovskite Cathode for Low-Temperature Solid Oxide Fuel Cells (LT-SOFCs)
Layered perovskite oxides are considered as promising cathode materials for the solid oxide fuel cell (SOFC) due to their high electronic/ionic conductivity and fast oxygen kinetics at low temperature. Many researchers have focused on further improving the electrochemical performance of the layered perovskite material by doping various metal ions into the B-site. Herein, we report that Sc3+ doping into the layered perovskite material, PrBaCo2O5+ (PBCO), shows a positive effect of increasing electrochemical performances. We confirmed that Sc3+ doping could provide a favorable crystalline structure of layered perovskite for oxygen ion transfer in the lattice with improved Gold-schmidt tolerance factor and specific free volume. Consequently, the Sc3+ doped PBCO exhibits a maximum power density of 0.73 W cm(-2) at 500 degrees C, 1.3 times higher than that of PBCO. These results indicate that Sc3+ doping could effectively improve the electrochemical properties of the layered perovskite material, PBCO
The bent conformation of poly(A)-binding protein induced by RNA-binding is required for its translational activation function
A recent study revealed that poly(A)-binding protein (PABP) bound to poly(A) RNA exhibits a sharply bent configuration at the linker region between RNA-recognition motif 2 (RRM2) and RRM3, whereas free PABP exhibits a highly flexible linear configuration. However, the physiological role of the bent structure of mRNA-bound PABP remains unknown. We investigated a role of the bent structure of PABP by constructing a PABP variant that fails to form the poly(A)-dependent bent structure but maintains its poly (A)-binding activity. We found that the bent structure of PABP/poly(A) complex is required for PABP's efficient interaction with eIF4G and eIF4G/eIF4E complex. Moreover, the mutant PABP had compromised translation activation function and failed to augment the formation of 80S translation initiation complex in an in vitro translation system. These results suggest that the bent conformation of PABP, which is induced by the interaction with 30 poly(A) tail, mediates poly(A)-dependent translation by facilitating the interaction with eIF4G and the eIF4G/eIF4E complex. The preferential binding of the eIF4G/eIF4E complex to the bent PABP/poly(A) complex seems to be a mechanism discriminating the mRNA-bound PABPs participating in translation from the idling mRNA-unbound PABPs.111Ysciescopu
eIF2A, an initiator tRNA carrier refractory to eIF2 kinases, functions synergistically with eIF5B
The initiator tRNA (Met-tRNA(i)(Met)) at the P site of the small ribosomal subunit plays an important role in the recognition of an mRNA start codon. In bacteria, the initiator tRNA carrier, IF2, facilitates the positioning of Met-tRNAiMet on the small ribosomal subunit. Eukarya contain the Met-tRNAiMet carrier, eIF2 (unrelated to IF2), whose carrier activity is inhibited under stress conditions by the phosphorylation of its -subunit by stress-activated eIF2 kinases. The stress-resistant initiator tRNA carrier, eIF2A, was recently uncovered and shown to load Met-tRNAiMet on the 40S ribosomal subunit associated with a stress-resistant mRNA under stress conditions. Here, we report that eIF2A interacts and functionally cooperates with eIF5B (a homolog of IF2), and we describe the functional domains of eIF2A that are required for its binding of Met-tRNAiMet, eIF5B, and a stress-resistant mRNA. The results indicate that the eukaryotic eIF5B-eIF2A complex functionally mimics the bacterial IF2 containing ribosome-, GTP-, and initiator tRNA-binding domains in a single polypeptide.112Ysciescopu
Deep learning-based statistical noise reduction for multidimensional spectral data
In spectroscopic experiments, data acquisition in multi-dimensional phase
space may require long acquisition time, owing to the large phase space volume
to be covered. In such case, the limited time available for data acquisition
can be a serious constraint for experiments in which multidimensional spectral
data are acquired. Here, taking angle-resolved photoemission spectroscopy
(ARPES) as an example, we demonstrate a denoising method that utilizes deep
learning as an intelligent way to overcome the constraint. With readily
available ARPES data and random generation of training data set, we
successfully trained the denoising neural network without overfitting. The
denoising neural network can remove the noise in the data while preserving its
intrinsic information. We show that the denoising neural network allows us to
perform similar level of second-derivative and line shape analysis on data
taken with two orders of magnitude less acquisition time. The importance of our
method lies in its applicability to any multidimensional spectral data that are
susceptible to statistical noise.Comment: 8 pages, 8 figure
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