238 research outputs found
Poly(ethylene glycol)-conjugated surfactants promote or inhibit aggregation of phospholipids
AbstractThe calcium-induced aggregation of dilauroyl phosphatidic acid (DLPA) suspensions, with or without added poly(ethylene oxide) (PEO)-conjugated surfactants containing 4 to 30 ethylene oxide subunits, were monitored by turbidity measurement and quasi-elastic light scattering (QLS). The aggregation was inhibited (protected) by the incorporated PEO surfactant for most samples, while a window for promotive effect was found for samples with low surface coverage by the PEO moiety of the incorporated surfactant. Promotion occurs only when the aggregation is slow and at a low level. The promotion is explained by the synergistic effect of PEO and divalent calcium cations when the steric repulsion is weak. The promotion/protection crossover is a display between the PEO/calcium synergistic effect and the steric repulsion
Privacy Preservation by Intermittent Transmission in Cooperative LQG Control Systems
In this paper, we study a cooperative linear quadratic Gaussian (LQG) control
system with a single user and a server. In this system, the user runs a process
and employs the server to meet the needs of computation. However, the user
regards its state trajectories as privacy. Therefore, we propose a privacy
scheme, in which the user sends data to the server intermittently. By this
scheme, the server's received information of the user is reduced, and
consequently the user's privacy is preserved. In this paper, we consider a
periodic transmission scheme. We analyze the performance of privacy
preservation and LQG control of different transmission periods. Under the given
threshold of the control performance loss, a trade-off optimization problem is
proposed. Finally, we give the solution to the optimization problem
Segatron: Segment-Aware Transformer for Language Modeling and Understanding
Transformers are powerful for sequence modeling. Nearly all state-of-the-art
language models and pre-trained language models are based on the Transformer
architecture. However, it distinguishes sequential tokens only with the token
position index. We hypothesize that better contextual representations can be
generated from the Transformer with richer positional information. To verify
this, we propose a segment-aware Transformer (Segatron), by replacing the
original token position encoding with a combined position encoding of
paragraph, sentence, and token. We first introduce the segment-aware mechanism
to Transformer-XL, which is a popular Transformer-based language model with
memory extension and relative position encoding. We find that our method can
further improve the Transformer-XL base model and large model, achieving 17.1
perplexity on the WikiText-103 dataset. We further investigate the pre-training
masked language modeling task with Segatron. Experimental results show that
BERT pre-trained with Segatron (SegaBERT) can outperform BERT with vanilla
Transformer on various NLP tasks, and outperforms RoBERTa on zero-shot sentence
representation learning.Comment: Accepted by AAAI 202
Research on the Influence of Raceway Waviness on the Vibration Characteristics of Deep Groove Ball Bearings
The dynamics model of a 2-degree-of-freedom deep groove ball bearing is established by incorporating the raceway surface waviness model comprising multiple sinusoidal functions superposition. The model is solved using the fourth-order Runge-Kutta method to obtain the vibration characteristics including displacement, velocity, acceleration, and frequency of the bearing. Validation of the model is accomplished through comparison with theoretical vibration frequencies. The influence of the amplitude of waviness of the inner and outer ring raceway surfaces of deep groove ball bearings on the vibration displacement, peak-to-peak vibration displacement and root-mean-square vibration acceleration is analyzed, and the results show that as the amplitude of the inner and outer ring raceway surfaces waviness increases, all the vibration characteristic indexes increase, indicating that the vibration amplitude of the bearings as well as the energy of the waviness-induced shock waveforms increase with the increase of the amplitude of the waviness
Progressive Multi-Scale Residual Network for Single Image Super-Resolution
Multi-scale convolutional neural networks (CNNs) achieve significant success
in single image super-resolution (SISR), which considers the comprehensive
information from different receptive fields. However, recent multi-scale
networks usually aim to build the hierarchical exploration with different sizes
of filters, which lead to high computation complexity costs, and seldom focus
on the inherent correlations among different scales. This paper converts the
multi-scale exploration into a sequential manner, and proposes a progressive
multi-scale residual network (PMRN) for SISR problem. Specifically, we devise a
progressive multi-scale residual block (PMRB) to substitute the larger filters
with small filter combinations, and gradually explore the hierarchical
information. Furthermore, channel- and pixel-wise attention mechanism (CPA) is
designed for finding the inherent correlations among image features with
weighting and bias factors, which concentrates more on high-frequency
information. Experimental results show that the proposed PMRN recovers
structural textures more effectively with superior PSNR/SSIM results than other
small networks. The extension model PMRN with self-ensemble achieves
competitive or better results than large networks with much fewer parameters
and lower computation complexity.Comment: This work has been submitted to the IEEE for possible publication.
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Deformable 3D Gaussians for High-Fidelity Monocular Dynamic Scene Reconstruction
Implicit neural representation has opened up new avenues for dynamic scene
reconstruction and rendering. Nonetheless, state-of-the-art methods of dynamic
neural rendering rely heavily on these implicit representations, which
frequently struggle with accurately capturing the intricate details of objects
in the scene. Furthermore, implicit methods struggle to achieve real-time
rendering in general dynamic scenes, limiting their use in a wide range of
tasks. To address the issues, we propose a deformable 3D Gaussians Splatting
method that reconstructs scenes using explicit 3D Gaussians and learns
Gaussians in canonical space with a deformation field to model monocular
dynamic scenes. We also introduced a smoothing training mechanism with no extra
overhead to mitigate the impact of inaccurate poses in real datasets on the
smoothness of time interpolation tasks. Through differential gaussian
rasterization, the deformable 3D Gaussians not only achieve higher rendering
quality but also real-time rendering speed. Experiments show that our method
outperforms existing methods significantly in terms of both rendering quality
and speed, making it well-suited for tasks such as novel-view synthesis, time
synthesis, and real-time rendering
Deformation characteristics and exploration potential of the West Kunlun foreland fold-and-thrust belt
The West Kunlun foreland is dominated by segmented fold-and-thrust belts with significant potential for hydrocarbon exploration, while the extent of exploration in this area has been relatively limited. In this paper, by conducting complex structural interpretation, the geometric and kinematic characteristics, as well as the variations in the segmented fold-and-thrust belts within this region are revealed. The West Kunlun foreland fold-and-thrust belts are divided into three structural segments, which exhibit distinct structural styles. The Pusha-Kedong segment in the east is characterized by large-scale northward propagation, with high-angle basement-involved faults in the root belt and thin-skinned thrusts in the front belt. Additionally, three-row anticlines developed in the middle to the upper structural layers. The Kashi-Yecheng segment, located in the middle, is characterized by strike-slip faults and basement-involved structural wedges transitioning to detachment structures. Within this segment, the Sugaite structure in the mountain front is a wedge structure composed of basement-involved faults and an upper back-thrust fault. Meanwhile, the Yingjisha structure in the thrust front consists of a fold in the lower part and a back-thrust system above it. The lower fold is controlled by the Cambrian detachment thrust, which terminates upward in the Paleogene, while the back-thrust faults truncate upper structural layers and terminate downwards in the Miocene strata. The Wupoer segment in the northwest is controlled by the Main Pamir Thrust and the Front Pamir Thrust, which are low angular forward thrust faults with an arc distribution. A piggyback basin has developed in the root belt and upper structural layer since the Pliocene. Based on the deformation characteristics and the accumulation of oil-gas reservoirs discovered so far, two types of oil and gas-rich thrust belts with different hydrocarbon exploration fields in the West Kunlun foreland are described.Document Type: Original articleCited as: Jiang, L., Dong, H., Li, Y., Zhao, W., Zhang, Y., Bo, D. Deformation characteristics and exploration potential of the West Kunlun foreland fold-and-thrust belt. Advances in Geo-Energy Research, 2024, 11(3): 181-193. https://doi.org/10.46690/ager.2024.03.0
Iterative Network for Image Super-Resolution
Single image super-resolution (SISR), as a traditional ill-conditioned
inverse problem, has been greatly revitalized by the recent development of
convolutional neural networks (CNN). These CNN-based methods generally map a
low-resolution image to its corresponding high-resolution version with
sophisticated network structures and loss functions, showing impressive
performances. This paper proposes a substantially different approach relying on
the iterative optimization on HR space with an iterative super-resolution
network (ISRN). We first analyze the observation model of image SR problem,
inspiring a feasible solution by mimicking and fusing each iteration in a more
general and efficient manner. Considering the drawbacks of batch normalization,
we propose a feature normalization (FNorm) method to regulate the features in
network. Furthermore, a novel block with F-Norm is developed to improve the
network representation, termed as FNB. Residual-in-residual structure is
proposed to form a very deep network, which groups FNBs with a long skip
connection for better information delivery and stabling the training phase.
Extensive experimental results on testing benchmarks with bicubic (BI)
degradation show our ISRN can not only recover more structural information, but
also achieve competitive or better PSNR/SSIM results with much fewer parameters
compared to other works. Besides BI, we simulate the real-world degradation
with blur-downscale (BD) and downscalenoise (DN). ISRN and its extension ISRN+
both achieve better performance than others with BD and DN degradation models.Comment: 12 pages, 14 figure
An efficient approach to separate CO2 using supersonic flows for carbon capture and storage
The mitigation of CO2 emissions is an effective measure to solve the climate change issue. In the present study, we propose an alternative approach for CO2 capture by employing supersonic flows. For this purpose, we first develop a computational fluid dynamics (CFD) model to predict the CO2 condensing flow in a supersonic nozzle. Adding two transport equations to describe the liquid fraction and droplet number, the detailed numerical model can describe the heat and mass transfer characteristics during the CO2 phase change process under the supersonic expansion conditions. A comparative study is performed to evaluate the effect of CO2 condensation using the condensation model and dry gas assumption. The results show that the developed CFD model predicts accurately the distribution of the static temperature contrary to the dry gas assumption. Furthermore, the condensing flow model predicts a CO2 liquid fraction up to 18.6% of the total mass, which leads to the release of the latent heat to the vapour phase. The investigation performed in this study suggests that the CO2 condensation in supersonic flows provides an efficient and eco-friendly way to mitigate the CO2 emissions to the environment
Effect of superabsorbent polymer on mechanical properties of cement stabilized base and its mechanism
Superabsorbent polymers (SAPs) are cross-linked polymers that can absorb and retain large amounts of water. In recent years, a growing interest was seen in applying SAPs in concrete to improve its performance due to its efficiency in mitigating shrinkage. This paper presents findings in a study on effect of SAPs on performance of cement-treated base (CTB), using the experience of internal curing of concrete. CTB specimens with and without SAPs were prepared and tested in the laboratory. Tests conducted include mechanical property testing, dry shrinkage testing, differential thermal analysis, mercury intrusion porosimetry and scanning electron microscope testing. It was found that 7-day and 28-day unconfined compressive strength of CTB specimens with SAPs was higher than regular CTB specimens. 28d compressive strength of CTB specimens with SAPs made by Static pressure method was 5.87 MPa, which is 27% higher than that of regular CTB specimens. Drying shrinkage of CTB specimens with SAPs was decreased by 52.5% comparing with regular CTB specimens. Through the microstructure analysis it was found that CTB specimens with SAPs could produce more hydration products, which is also the reason for the strength improvement
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