4,405 research outputs found
Numerical Simulation of Instability Characteristic in Pump turbines
International audienceIn classical pumps, there is single positive slope part on the curve of pump performance, named head-drop phenomenon. However, a second head-drop phenomenon is found in our experiments in the pump mode of some medium pump turbines. The flow rate of this second head-drop phenomenon is 0.68-0.71 times of the design flow rate. As shown in our experimental results, it is significantly influenced by the complex vortices in the impeller inlet domain. Using SST k-É· turbulence model, numerical simulations are conducted to reveal its mechanism. After comparing numerical simulation results with the experimental results, it can be concluded that this second head-drop is closely related with the complex vortices in the impeller inlet. The complex vortices, due to the transmission flow between separated flow and back flow, is responsible for this second head-drop phenomenon
Second-Harmonic Generation and Spectrum Modulation by Active Nonlinear Metamaterial
The nonlinear properties of a metamaterial sample composed of double-layer
metallic patterns and voltage controllable diodes are experimentally
investigated. Second harmonics and spectrum modulations are clearly observed in
a wide band of microwave frequencies, showing that this kind of metamaterial is
not only tunable by low DC bias voltage, but also behaves strong nonlinear
property under a small power incidence. These properties are difficult to be
found in normal, naturally occurring materials.Comment: 14 pages, 4 figure
Lecture Notes on Generalized Symmetries and Applications
In this lecture note, we give a basic introduction to the rapidly developing
concepts of generalized symmetries, from the perspectives of both high energy
physics and condensed matter physics. In particular, we emphasize on the
(invertible) higher-form and higher-group symmetries. For the physical
applications, we discuss the geometric engineering of QFTs in string theory and
the symmetry-protected topological (SPT) phases in condensed matter physics.
The lecture note is based on a short course on generalized symmetries,
jointly given by Yi-Nan Wang and Qing-Rui Wang in Feb. 2023, which took place
at School of Physics, Peking University
(https://indico.ihep.ac.cn/event/18796/).Comment: 70 pages, Invited contribution for the Special Issue "Symmetry and
Chaos in Quantum Mechanics" for Symmetry (Ed. Dr. Cheng Peng
Learning Cross-modality Information Bottleneck Representation for Heterogeneous Person Re-Identification
Visible-Infrared person re-identification (VI-ReID) is an important and
challenging task in intelligent video surveillance. Existing methods mainly
focus on learning a shared feature space to reduce the modality discrepancy
between visible and infrared modalities, which still leave two problems
underexplored: information redundancy and modality complementarity. To this
end, properly eliminating the identity-irrelevant information as well as making
up for the modality-specific information are critical and remains a challenging
endeavor. To tackle the above problems, we present a novel mutual information
and modality consensus network, namely CMInfoNet, to extract modality-invariant
identity features with the most representative information and reduce the
redundancies. The key insight of our method is to find an optimal
representation to capture more identity-relevant information and compress the
irrelevant parts by optimizing a mutual information bottleneck trade-off.
Besides, we propose an automatically search strategy to find the most prominent
parts that identify the pedestrians. To eliminate the cross- and intra-modality
variations, we also devise a modality consensus module to align the visible and
infrared modalities for task-specific guidance. Moreover, the global-local
feature representations can also be acquired for key parts discrimination.
Experimental results on four benchmarks, i.e., SYSU-MM01, RegDB,
Occluded-DukeMTMC, Occluded-REID, Partial-REID and Partial\_iLIDS dataset, have
demonstrated the effectiveness of CMInfoNet
Activation of protease-activated receptor 2 reduces glioblastoma cell apoptosis
BACKGROUND: The pathogenesis of glioma is unclear. The disturbance of the apoptosis process plays a critical role in glioma growth. Factors regulating the apoptosis process are to be further understood. This study aims to investigate the role of protease activated receptor-2 (PAR2) in regulation the apoptosis process in glioma cells. RESULTS: The results showed that U87 cells and human glioma tissue expressed PAR2. Exposure to tryptase, or the PAR2 active peptide, increased STAT3 phosphorylation in the radiated U87 cells, reduced U87 cell apoptosis, suppressed the expression of p53 in U87 cells. CONCLUSIONS: Activation of PAR2 can reduce the radiated U87 cell apoptosis via modulating the expression of p53. The results implicate that PAR2 may be a novel therapeutic target in the treatment of glioma
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