Beihang University

About: Beihang University is a education organization based out in Beijing, China. It is known for research contribution in the topics: Computer science & Control theory. The organization has 67002 authors who have published 73507 publications receiving 975691 citations. The organization is also known as: Beijing University of Aeronautics and Astronautics.

Piezoelectric actuation of direct-write electrospun fibers

Abstract: Piezoelectric actuation of doubly clamped, electrospun poly (vinylidene fluoride) (PVDF) fibers fabricated by a direct-write process has been demonstrated. Near-field electrospinning (NFES) has been utilized to fabricate PVDF fibers with good piezoelectric properties by means of the in situ electrical poling and mechanical stretching process. Experimentally, PVDF fibers have responded to both piezoelectric and electrostatic effects and a double-electrode approach has been used to minimize the electrostatic effect. An average piezoelectric coefficient d33 of −57.6 pm/V has been characterized from fabricated fibers and this value is about twice larger than the value reported in PVDF thin-films. Various complex patterns of PVDF fibers have been deposited using NFES, enabling possible array formats for fiber-based actuators with possible applications including artificial muscles and switches.

Enhancing Quality for HEVC Compressed Videos

Abstract: The latest High Efficiency Video Coding (HEVC) standard has been increasingly applied to generate video streams over the Internet However, HEVC compressed videos may incur severe quality degradation, particularly at low bit rates Thus, it is necessary to enhance the visual quality of HEVC videos at the decoder side To this end, this paper proposes a quality enhancement convolutional neural network (QE-CNN) method that does not require any modification of the encoder to achieve quality enhancement for HEVC In particular, our QE-CNN method learns QE-CNN-I and QE-CNN-P models to reduce the distortion of HEVC I and P/B frames, respectively The proposed method differs from the existing CNN-based quality enhancement approaches, which only handle intra-coding distortion and are thus not suitable for P/B frames Our experimental results validate that our QE-CNN method is effective in enhancing quality for both I and P/B frames of HEVC videos To apply our QE-CNN method in time-constrained scenarios, we further propose a time-constrained quality enhancement optimization (TQEO) scheme Our TQEO scheme controls the computational time of QE-CNN to meet a target, meanwhile maximizing the quality enhancement Next, the experimental results demonstrate the effectiveness of our TQEO scheme from the aspects of time control accuracy and quality enhancement under different time constraints Finally, we design a prototype to implement our TQEO scheme in a real-time scenario

Cross-talk between LOX-1 and PCSK9 in vascular tissues

Abstract: Aims Lectin-like ox-LDL receptor-1 (LOX-1) plays an important role in inflammatory diseases, such as atherosclerosis. Proprotein convertase subtilisin/kexin type 9 (PCSK9) modulates LDL receptor degradation and influences serum LDL levels. The present study was designed to investigate the possible interaction between PCSK9 and LOX-1. Methods and results In the first set of experiments, human vascular endothelial cells and smooth muscle cells were studied at baseline and after lipopolysaccharide (LPS) treatment (to create an inflammatory state). Both PCSK9 and LOX-1 were strongly induced by LPS treatment. To define the role of PCSK9 in LOX-1 expression, cells were transfected with siRNA against PCSK9 , which resulted in reduced LOX-1 expression and function. On the other hand, cells exposed to recombinant hPCSK9 revealed enhanced LOX-1 expression ( P < 0.05). To determine whether LOX-1 also regulates PCSK9, cultured cells in which LOX-1 was knocked down by siRNA expressed less PCSK9, whereas those transfected with hLOX-1 cDNA showed increased PCSK9 expression. The second set of experiments was carried out in wild-type (WT) and gene knockout (KO; LOX-1 and PCSK9) mice; LOX-1 KO mice showed much less PCSK9 ( P < 0.05 vs. WT mice). PCSK9- KO mice showed much less LOX-1 ( P < 0.05 vs. WT mice). Furthermore, we observed that mitochondrial reactive oxygen species (mtROS) plays an initiating role in the LOX-1/PCSK9 interaction, since mtROS induction enhanced and its inhibition reduced the expression of both PCSK9 and LOX-1. We also found that both LOX-1 and PCSK9 regulate adhesion molecules vascular cell adhesion molecule-1 expression. Finally, oxidized low-density lipoprotein and tumour necrosis factor-α, pro-inflammatory stimuli besides LPS, regulated PCSK9 expression that is mediated by the NF-κB signalling pathway. Conclusions These observations suggest that LOX-1 and PCSK9 positively influence each other's expression, especially during an inflammatory reaction. mtROS appear to be important initiators of PCSK9/LOX-1 expression.

Amorphous Nanocages of Cu-Ni-Fe Hydr(oxy)oxide Prepared by Photocorrosion For Highly Efficient Oxygen Evolution.

Abstract: Electrochemical water splitting requires efficient, low-cost water oxidation catalysts to accelerate the sluggish kinetics of the water oxidation reaction. A rapid photocorrosion method is now used to synthesize the homogeneous amorphous nanocages of Cu-Ni-Fe hydr(oxy)oxide as a highly efficient electrocatalyst for the oxygen evolution reaction (OER). The as-fabricated product exhibits a low overpotential of 224 mV on a glassy carbon electrode at 10 mA cm-2 (even lower down to 181 mV when supported on Ni foam) with a Tafel slope of 44 mV dec-1 for OER in an alkaline solution. The obtained catalyst shows an extraordinarily large mass activity of 1464.5 A g-1 at overpotential of 300 mV, which is the highest mass activity for OER. This synthetic strategy may open a brand new pathway to prepare copper-based ternary amorphous nanocages for greatly enhanced oxygen evolution.

A Smart Manufacturing Service System Based on Edge Computing, Fog Computing, and Cloud Computing

Abstract: The state-of-the-art technologies in new generation information technologies (New IT) greatly stimulate the development of smart manufacturing. In a smart manufacturing environment, more and more devices would be connected to the Internet so that a large volume of data can be obtained during all phases of the product lifecycle. Cloud-based smart manufacturing paradigm facilitates a new variety of applications and services to analyze a large volume of data and enable large-scale manufacturing collaboration. However, different factors, such as the network unavailability, overfull bandwidth, and latency time, restrict its availability for high-speed and low-latency real-time applications. Fog computing and edge computing extended the compute, storage, and networking capabilities of the cloud to the edge, which will respond to the above-mentioned issues. Based on cloud computing, fog computing, and edge computing, in this paper, a hierarchy reference architecture is introduced for smart manufacturing. The architecture is expected to be applied in the digital twin shop floor, which opens a bright perspective of new applications within the field of manufacturing.