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204 results on '"Zhu, Liwen"'

31. Quantitative analysis of the morphing wing mechanism of raptors: Bionic design of Falco Peregrinus wing skeleton.

Author

Tang, Di, Shi, Wenxi, Liu, Dawei, Yang, Yin, Zhu, Liwen, and Xu, Lang

Subjects
PEREGRINE falcon, ELBOW joint, MUSCULOSKELETAL system, WRIST joint, BIONICS
Abstract

The wing is one of the most important parts of a bird's locomotor system and is the inspiration origination for bionic wing design. During wing motions, the wing shape is closely related to the rotation angles of wing bones. Therefore, the research on the law of bone movement in the process of wing movement can be good guidance for the design of the bionic morphing wing. In this paper, the skeletal posture of the peregrine falcon wing during the extension/flexion is studied to obtain critical data on skeletal posture. Since an elbow joint and a wrist joint rotate correlatively to drive a wing to flex/extend, the wing skeleton is simplified as a four-bar mechanism in this paper. The degree of reproduction of wing skeleton postures was quantitatively analyzed using the four-bar mechanism model, and the bionic wing skeleton was designed. It is found that the wing motions have been reproduced with high precision. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Cuproptosis‐Driven Enhancement of Thermotherapy by Sequentially Response Cu2‐xSe via Copper Chemical Transition.

Author

Chan, Leung, Liu, Yongkang, Chen, Muhe, Su, Yanhong, Guo, Junxian, Zhu, Liwen, Zhan, Meixiao, Chen, Tianfeng, and Lu, Ligong

Subjects
THERMOTHERAPY, MALEIC anhydride, REACTIVE oxygen species, TUMOR treatment, TRICARBOXYLIC acids, SEMIMETALS, COPPER
Abstract

Activation of cuproptosis pathway has been reported to hold great potential in the application of tumor treatment. But the efficacy of cuproptosis seriously limited by the insufficient accumulation in the tumor sites. Therefore, herein based on the strong stabilization effects of the metalloid element selenium (Se) on copper (Cu), a photothermic Cu2‐xSe nanoparticle encapsulated with bioresponsive dimethyl maleic anhydride (DMMA@Cu2‐xSe) as a copper‐carrier to improve the copper accumulation in tumor is constructed, thus achieving cuproptosis‐driven enhancement of thermotherapy. This nanosystem exhibits the enhancement of tumor cellular uptake by a weak acid‐triggered charge‐switching ability. Next step, the exposed Cu2‐xSe is oxidized and releases divalent copper by high‐level oxide. Then, the abundant copper induces more dihydrolipoamide S‐acetyltransferase oligomerization to down‐regulate FDX1 and tricarboxylic acid cycle‐related proteins, which leads to inhibiting aerobic respiration. Cuproptosis‐induced mitochondrial damage further improves thermotherapy by up‐regulating reactive oxygen species (ROS). In addition, the generated ROS also promotes copper release to strengthen cuproptosis, and eventually improves tumor thermotherapy in turn. In general, DMMA@Cu2‐xSe with sequentially triggered copper‐release, efficient cuproptosis, and appropriate photothermal is a self‐enhanced nanoplatform for cuproptosis‐driven enhancement of thermotherapy. [ABSTRACT FROM AUTHOR]

Published
2023
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45. Multi-Agent Sequential Decision-Making via Communication

Author

Ding, Ziluo, Su, Kefan, Hong, Weixin, Zhu, Liwen, Huang, Tiejun, and Lu, Zongqing

Subjects
FOS: Computer and information sciences, Computer Science - Machine Learning, Computer Science - Multiagent Systems, Multiagent Systems (cs.MA), Machine Learning (cs.LG)
Abstract

Communication helps agents to obtain information about others so that better coordinated behavior can be learned. Some existing work communicates predicted future trajectory with others, hoping to get clues about what others would do for better coordination. However, circular dependencies sometimes can occur when agents are treated synchronously so it is hard to coordinate decision-making. In this paper, we propose a novel communication scheme, Sequential Communication (SeqComm). SeqComm treats agents asynchronously (the upper-level agents make decisions before the lower-level ones) and has two communication phases. In negotiation phase, agents determine the priority of decision-making by communicating hidden states of observations and comparing the value of intention, which is obtained by modeling the environment dynamics. In launching phase, the upper-level agents take the lead in making decisions and communicate their actions with the lower-level agents. Theoretically, we prove the policies learned by SeqComm are guaranteed to improve monotonically and converge. Empirically, we show that SeqComm outperforms existing methods in various multi-agent cooperative tasks., 20 pages

Published
2022

47. Thickness-dependent flexoresistance in SrTiO3 thin films.

Author

Zhu, Liwen, Liang, Renhong, Ye, Mao, Shu, Longlong, Zheng, Renkui, and Ke, Shanming

Subjects
*THIN films, *STRAINS & stresses (Mechanics), *ATOMIC force microscopes, *THICK films, *SURFACE morphology, *RECEIVER operating characteristic curves, *FLEXOELECTRICITY
Abstract

We report a thickness-dependent flexoresistance effect caused by strain gradient in SrTiO3 (STO) epitaxial thin films. The strain gradient in STO was induced by using an atomic force microscope diamond-coated tip. The depolarization field caused by the strain gradient changes the electrical state of the film, resulting in a decrease in the resistance of the films by 4–6 orders of magnitude. By testing the current–voltage (I–V) curves of STO films with different thicknesses, it is found that the flexoresistance behavior of STO films is obvious thickness dependent: the thicker the film, the higher the force threshold to trigger the film to enter a highly conductive state. The comparison of the surface morphology before and after the I–V test with loading shows that only when the thickness of the STO film is below 8 nm, the film can enter the conductive state from the insulating state without damaging the surface. During the electrical state switching process, the strain gradient caused by tip loading play an important role in the modification of the film barrier. [ABSTRACT FROM AUTHOR]

Published
2023
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