25 research outputs found
Adversarial Examples in the Physical World: A Survey
Deep neural networks (DNNs) have demonstrated high vulnerability to
adversarial examples. Besides the attacks in the digital world, the practical
implications of adversarial examples in the physical world present significant
challenges and safety concerns. However, current research on physical
adversarial examples (PAEs) lacks a comprehensive understanding of their unique
characteristics, leading to limited significance and understanding. In this
paper, we address this gap by thoroughly examining the characteristics of PAEs
within a practical workflow encompassing training, manufacturing, and
re-sampling processes. By analyzing the links between physical adversarial
attacks, we identify manufacturing and re-sampling as the primary sources of
distinct attributes and particularities in PAEs. Leveraging this knowledge, we
develop a comprehensive analysis and classification framework for PAEs based on
their specific characteristics, covering over 100 studies on physical-world
adversarial examples. Furthermore, we investigate defense strategies against
PAEs and identify open challenges and opportunities for future research. We aim
to provide a fresh, thorough, and systematic understanding of PAEs, thereby
promoting the development of robust adversarial learning and its application in
open-world scenarios.Comment: Adversarial examples, physical-world scenarios, attacks and defense
Human Performance Modeling and Rendering via Neural Animated Mesh
We have recently seen tremendous progress in the neural advances for
photo-real human modeling and rendering. However, it's still challenging to
integrate them into an existing mesh-based pipeline for downstream
applications. In this paper, we present a comprehensive neural approach for
high-quality reconstruction, compression, and rendering of human performances
from dense multi-view videos. Our core intuition is to bridge the traditional
animated mesh workflow with a new class of highly efficient neural techniques.
We first introduce a neural surface reconstructor for high-quality surface
generation in minutes. It marries the implicit volumetric rendering of the
truncated signed distance field (TSDF) with multi-resolution hash encoding. We
further propose a hybrid neural tracker to generate animated meshes, which
combines explicit non-rigid tracking with implicit dynamic deformation in a
self-supervised framework. The former provides the coarse warping back into the
canonical space, while the latter implicit one further predicts the
displacements using the 4D hash encoding as in our reconstructor. Then, we
discuss the rendering schemes using the obtained animated meshes, ranging from
dynamic texturing to lumigraph rendering under various bandwidth settings. To
strike an intricate balance between quality and bandwidth, we propose a
hierarchical solution by first rendering 6 virtual views covering the performer
and then conducting occlusion-aware neural texture blending. We demonstrate the
efficacy of our approach in a variety of mesh-based applications and
photo-realistic free-view experiences on various platforms, i.e., inserting
virtual human performances into real environments through mobile AR or
immersively watching talent shows with VR headsets.Comment: 18 pages, 17 figure
Epidermal growth factor induces HCCR expression via PI3K/Akt/mTOR signaling in PANC-1 pancreatic cancer cells
<p>Abstract</p> <p>Background</p> <p>Human cervical cancer oncoprotein 1 (HCCR-1), reported as a negative regulator of p53, is over-expressed in a variety of human cancers. However, it is yet unknown whether HCCR-1 plays any role in pancreatic cancer development. The aim of this study was to investigate the effect of epidermal growth factor on the expression of HCCR in pancreatic cancer cells, and to explore if PI3K/Akt/mTOR signaling pathway mediated this expression.</p> <p>Methods</p> <p>A polyclonal antibody against HCCR protein was raised by immunizing Balb/c mice with the purified recombinant protein pMBPc-HCCR. Tissue samples were constructed on a tissue chip, and the expression of HCCR was investigated by immunohistochemistry assay and Western blotting. Pancreatic cell line, PANC-1 cells were stably transfected with plasmids containing sense-HCCR-1 fragment and HCCR siRNA fragment. MTT and transwell assay were used to investigate the proliferation and invasion of stable tansfectants. The specific inhibitor of PI3K and mTOR was used to see if PI3K/mTOR signal transduction was involved in the induction of HCCR gene expression. A Luciferase assay was used to see if Akt can enhance the HCCR promoter activity.</p> <p>Results</p> <p>HCCR was up-regulated in pancreatic tumor tissues (mean Allred score 4.51 ± 1.549 <it>vs</it>. 2.87 ± 2.193, P < 0.01), especially with high expression in poorly differentiated pancreatic cancer. The growth of cells decreased in HCCR-1 siRNA transfected cells compared with vector transfectants. The number of invasion cells was significantly lower in HCCR-1 siRNA transfected cells (24.4 ± 9.9) than that in vector transfectants (49.1 ± 15.4). Treatment of PANC-1 cells with epidermal growth factor increased HCCR protein level in a dose- and time-dependent manner. However, application of LY294002 and rapamycin caused a dramatic reduction of epidermal growth factor-induced HCCR expression. Over-expression of exogenous constitutively active Akt increased the HCCR promoter activity; in contrast, dominant negative Akt decreased the promoter activity.</p> <p>Conclusions</p> <p>EGF-induced HCCR-1 over-expression is mediated by PI3K/AKT/mTOR signaling which plays a pivotal role in pancreatic tumor progression, suggesting that HCCR-1 could be a potential target for cancer therapeutics.</p
A Fault Feature Extraction Method for Rolling Bearing Based on Intrinsic Time-Scale Decomposition and AR Minimum Entropy Deconvolution
It is very difficult to extract the feature frequency of the vibration signal of the rolling bearing early weak fault and in order to extract its feature frequency quickly and accurately. A method of extracting early weak fault vibration signal feature frequency of the rolling bearing by intrinsic time-scale decomposition (ITD) and autoregression (AR) minimum entropy deconvolution (MED) is proposed in this paper. Firstly, the original early weak fault vibration signal of the rolling bearing is decomposed by the ITD algorithm to proper rotations (PRs) with fault feature frequency. Then, the sample entropy value of each PR is calculated to find the largest PRs of the sample entropy. Finally, the AR-MED filtering algorithm is utilized to filter and reduce the noise of the largest PRs of the sample entropy value, and the early weak fault vibration signal feature frequency of the rolling bearing is accurately extracted. The results show that the ITD-AR-MED method can extract the early weak fault vibration signal feature frequency of the rolling bearing accurately
Interfacial microstructure and shear strength of TC4 alloy joints vacuum brazed with Ti-Zr-Ni-Cu filler metal
2020 Elsevier B.V. Ti-6Al-4V alloy was successfully vacuum brazed with a commercial Ti-37.5Zr-10Ni-15Cu (wt.%) filler metal. The effect of brazing temperature and time on the microstructure and shear strength of the brazed joints were investigated. When the brazing temperature was 905 °C for 10 min, the typical interfacial microstructure of the brazed joint were a single layer of α-Ti with a high concentration of Ti, α-Ti, (Ti, Zr)2(Cu, Ni) intermetallic compound and eutectoid microstructure. Increasing the brazing temperature and time are beneficial to eliminate the (Ti, Zr)2(Cu, Ni) intermetallic compound that degrades the properties in the brazed joint. The shear strength of the brazed joint increases first and then decreases with brazing temperature, and increases with the extended holding time. The maximum shear strength of the brazed joint is 635.77 MPa at a brazing temperature of 920 °C for 30 min due to the high content of columnar α-Ti. Extending the brazing time is obviously beneficial to increasing the strength. The microstructure and shear strength of the brazed joint are highly dependent on brazing temperature and time