Fluid-enhanced surface diffusion controls intraparticle phase transformations

Li, Yiyang,Chen, Hungru,Lim, Kipil,Deng, Haitao D.,Lim, Jongwoo,Fraggedakis, Dimitrios,Attia, Peter M.,Lee, Sang Chul,Jin, Norman,Moš,kon, Jož,e,Guan, Zixuan,Gent, William E.,Hong, Jihyun,Yu Springer Science and Business Media LLC 2018 Nature Materials Vol.17 No.10

Hybrid Gradient Vector Fields Based on Maneuver Space for Path-following Guidance

Yiyang Zhao,Deyun Zhou,Zhen Yang,Xiaoyang Li,Jichuan Huang,Xiaofeng Lv 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

Guidance path-planning and following are two important functionalities of unmanned aerial vehicles (UAVs), but only a few approaches deal with both. In this study, an innovative hybrid gradient vector fields algorithm based on maneuver space (HGVFs-MS) for path-following guidance is proposed to control fixed-wing UAVs to follow a generated guidance path and oriented target curves in three-dimensional space, which can be any combination of straight lines, arcs, and helixes as motion primitives. The strategies designed in earlier studies have flaws that prevent the UAV from following arcs that make its turning angle too large. The switching strategy proposed in this study solves this problem by introducing the concept of the virtual waypoints. Finally, the performance of the HGVFs-MS algorithm is verified by three representative simulation scenarios. The simulation considers the constraints of the aircraft, and its results indicate that the algorithm performs well in following both lateral and longitudinal control, particularly for curved paths.

Online Recognition Method for Target Maneuver in UAV Autonomous Air Combat

Yicong Li,Zhen Yang,Xiaofeng Lv,Jichuan Huang,Yiyang Zhao,Deyun Zhou 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

In unmanned aerial vehicle (UAV) autonomous air combat, target maneuver online recognition is beneficial to predict the tactical intention of the target, which is of great significance to air combat situational awareness and decision-making assistance. However, the target trajectory data acquired by our airborne sensors may contain one or more maneuvers. The existing research methods mainly focus on the recognition of single maneuver trajectory which has been segmented according to maneuver segments or the segmentation of target maneuver trajectory by introducing human experience. The above methods can not meet the requirements of online recognition of the unknown continuous multi-segment maneuvers trajectory in autonomous air combat. In this paper, the online recognition problem of target maneuver is transformed into three classification problems, which are maneuver switch subsequence recognition problem, maneuver switch point localization problem and single maneuver recognition problem. The cascaded classification networks based on Long Short-Term Memory (LSTM) temporal feature extraction is used to map maneuver trajectory to maneuver category sequence. The algorithm proposed in this paper is tested by randomly selecting target trajectories, which can automatically segment the trajectories and recognize the correct categories. The average sequence similarity between the predicted maneuver category sequence and the real maneuver category sequence after segmentation and recognition on the test set is above 0.9. The feasibility and effectiveness of the proposed algorithm are verified.

Titanium Dioxide–Graphene–Polyaniline Hybrid for Nonenzymatic Detection of Glucose

Jiawen Du,Yiyang Tao,Zhichen Xiong,Xianglang Yu,Aijuan Xie,Shiping Luo,Xiazhang Li,Chao Yao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7

A novel titanium dioxide–graphene–polyaniline (TiO2–RGO–PANI) hybrid was prepared by the one-pot method and used as a nonenzymatic electrochemical sensor for glucose detection. The composition and structural morphology of the as-prepared composites were determined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The characterization results showed that TiO2–RGO–PANI is mainly composed of Ti, O, C and N and their weight percentages are 67.68%, 21.57%, 10.70% and 0.05%, respectively, indicating that the TiO2–RGO–PANI composite catalyst has been successfully prepared and presents a poriferous coral structure. A series of electrochemical tests such as cyclic voltammetry tests declared that TiO2–RGO–PANI composite possessed a low limit of detection (LOD) (7.46 μM), good repeatability, selectivity and stability. In the concentration range of 10–180 μM, the hybrid presented linear diffusion, and the linear equation was Ipa = 0.21338 + 0.01392 (C/mM), the correlation coefficient R2 = 0.9912. In addition, the comparison of the merits of this proposed electrode with some recent nonenzymatic glucose sensors indicates that this highly sensitive TiO2–RGO–PANI complex glucose sensor provides a simple, low-cost, nonenzymatic method for glucose detection, and has promising applications in clinical diagnostics and medical analysis.

Influence of wire mesh electrodes on the volume and surface characteristics of dielectric barrier discharge of atmospheric pressure helium

Liu Sheng,Li Jiamao,Zeng Yiyang,Chi Fangting,Xiao Chengjian 한국물리학회 2022 Current Applied Physics Vol.44 No.-

The dielectric barrier discharge of helium in a 6 mm gap at atmospheric pressure was studied. In this paper, the influence of electric field distribution on the uniformity of DBD is analyzed theoretically and verified by experiments. The experimental results show that the mesh electrode produces a local enhancement effect by affecting the electric field and then produces corona discharge, which provides seed electrons for the subsequent discharge process. The effects of mesh diameter and size on discharge uniformity and stability are analyzed, the electrode structure parameters are optimized, the method of a segmented electrode is proposed, and the discharge process and charge distribution are studied. The electrical diagnosis results of plasma technology show that the segmented mesh electrode reduces the breakdown voltage of DBD and increases the charge deposition.

Electrospinning Inorganic/Organic Nanohybridization Membranes with Hydrophobic and Oleophobic Performance

Tingting Zhang,Zihui Li,Ya Liu,Kangjia Ding,Yangfeng Guo,Yiyang Xu,Mengfan Sun,Dongfang Wang,Qian Li 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

Polytetrafluoroethylene (PTFE) nano-porous membrane has been widely used in various fields due to its excellent thermal stability and chemical stability. However, PTFE nanofiber membranes with simultaneous hydrophobic and oleophobic properties are essential to promote the application of PTFE. Here, based on inorganic/organic nanohybridization, we report a strategy for constructing nanostructures on fibers by adding nanoparticles, such as MOF and ZrO2. The results of FTIR and XRD confirmed MOF was synthesized successfully. At the same time, the SEM results showed UiO-66-(COOH)2 is spherical with an average diameter of 152 nm, and there is no agglomeration, which is suitable for electrospinning. Further, MOF and ZrO2 were payload into PTFE nanofibers. The results of SEM and AFM confirmed nanostructures will be more uniform and pronounced with the increase of UiO-66-(COOH)2 content, and nanostructures are most obvious when the content of UiO-66-(COOH)2 is 15%. The introduced nanostructures can increase the oil contact angle of the PTFE nano-porous membrane to 110° without introducing other groups, and further improve the water contact angle from 133° to 145°. Meanwhile, the introduction of a certain amount of hydrophilia groups can increase the oil contact angle to more than 120°. The simple strategy is of great significance to expand the application of PTFE fiber membrane in dealing with waste water treatment fields.

Prediction of the Axial Bearing Compressive Capacities of CFST Columns Based on Machine Learning Methods

Lusong Yu,Yuxing Zhang,Li Wang,Qiren Pan,Yiyang Wen 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.1

Concrete-fi lled steel tubes (CFSTs) are widely used in engineering structures due to their excellent mechanical properties and economic benefi ts. This study focused on the construction of artifi cial neural network (ANN) models with high prediction capabilities and prediction accuracies that could predict the axial compression load capacities of short CFST columns using machine learning methods. A database was created by searching literature published over the past 40 years regarding circular-CFST bearing-capacity testing. Three ANN models with diff erent input parameters were developed, and used the Whale Optimization Algorithm to optimize the network weights and thresholds, the core idea of which comes from the humpback whale's special bubble net attack method. Then, the predictions of the proposed machine learning models were also compared with the theoretical values produced by the formulas proposed in existing codes. The results show that the ANN models had higher accuracies and a wider application range than the existing code models. Based on the Garson's algorithm, we perform parameter sensitivity analysis on the network model to enhance the interpretability of the neural network model. Finally, a graphical user tool is built to make the strength of CFST can be predicted quickly.

Study on Cooperative Air-to-Ground Surveillance Planning and Controlling for Unmanned Aerial Vehicles

Shiyuan Chai,Zhen Yang,Jichuan Huang,Xiaoyang Li,Yiyang Zhao,Deyun Zhou 제어로봇시스템학회 2022 제어로봇시스템학회 국제학술대회 논문집 Vol.2022 No.11

The use of unmanned aerial vehicles (UAVs) for air-to-ground mission in complex environments has increased considerably in recent years. The numerous studies on UAVs cooperative air-to-ground mission controlling have been reported, but few have considered the impact of the communication instability due to electromagnetic interference (EMI) which is common in many air-to-ground applications. Under the influence of EMI, the air-to-ground mission stages are represented as a dynamic combination of several communication-available and communication-unavailable stages. Traditional cooperative surveillance algorithms cannot handle such situations well. In this study, we presented a method which based on Voronoi diagrams to solve the impact of communication outages, and an attention mechanism ant-colony optimization (AACO) algorithm was proposed for UAV path-planning control in air-to-ground surveillance missions. The controlling strategy is adaptively updated by introducing an attention mechanism for regular instruction information, a priori information, and emergent information of the mission to satisfy the mission target. Simulation results show that the proposed algorithm achieves better search performance than traditional algorithms in scenarios which include communication-available and communication-unavailable situations.

Constructing foldable cylindrical surfaces via unfolded waterbomb origami units

Zhao Yan,Wei Yinglei,Jia Yiyang,Li Shiling,Zhang Mingyue,Zeng Lanling,Yang Yang,Mitani Jun 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.4

Origami tessellations have shown the potential to be utilized for approximating curved target surfaces by folding a set of elemental units. As those units are in partially folded states, the origami approximation captures the outline of the target while demonstrating a corrugated surface. In this paper, we focus on the cylindrical surface and propose a method for constructing its discrete version via square or rectangular units with crease patterns inspired by the waterbomb tessellation. We unify the unit size through optimization to realize cost-efficient constructions. Three-dimensional curved structures are deployed by folding collinear creases between adjacent rows of units and the other creases in each row are remained unfolded. The deployed structure can still be folded to a compact state by folding all creases. To flexibly approximate the outline of the target surface, we analyse relationships between the width and height of the rectangular unit and utilize variations of the waterbomb tessellation to control the region of the origami structure when fully folded. The proposed method provides a novel solution to the so-called inverse-origami-design problem for generating foldable cylindrical surfaces using unfolded waterbomb origami units.

Exosomes Derived from Human Adipose Mesenchymal Stem Cells Inhibits Fibrosis and Treats Oral Submucous Fibrosis via the miR-181a-5p/Smad2 Axis

Shao Zifei,Xu Jinhao,Xu Xiaoyang,Wang Xiang,Zhou Yuxi,Li Yiyang,Li Kun 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.1

BACKGROUND: Oral submucous fibrosis (OSF) is a chronic disease with carcinogenic tendency that poses a non-negligible threat to human health. Exosomes derived from human adipose mesenchymal stem cells (ADSC-Exo) reduces visceral and cutaneous fibroses, but their role in OSF has received little attention. The aim of this study was to investigate the effects of ADSC-Exo on OSF and elucidate the mechanism. METHODS: In brief, ADSCs were extracted from adipose tissues and subjected to flow cytometry and induction culture. Fibroblasts were isolated from human buccal mucosa and subjected to immunofluorescence. Myofibroblasts were obtained from fibroblasts induced by arecoline and identified. Immunofluorescence assay confirmed that myofibroblasts could take up ADSC-Exo. The effects of ADSC-Exo on the proliferative and migratory capacities of myofibroblasts were examined using the Cell Counting Kit-8 and scratch assay. Real-time quantitative polymerase chain reaction (qPCR) was performed to evaluate mothers against decapentaplegic homolog 2 (Smad2), Smad3, Smad7, collagen type 1 (Col1), Col3, alpha smooth muscle actin (α-SMA), fibronectin, and vimentin. Western blotting was performed to detect phospho (p)-Smad2, Smad2, p-Smad2/3, Smad2/3, Smad7, Col1, Col3, α-SMA, fibronectin, and vimentin. Furthermore, the dual-luciferase reporter assay was performed to prove that miR-181a-5p in ADSC-Exo directly inhibited the expression of Smad2 mRNA to regulate the transforming growth factor beta (TGF-β) pathway. We also performed qPCR and western blotting to verify the results. RESULTS: ADSC-Exo could promote the proliferation and migration of myofibroblasts, reduce the expressions of p-smad2, Smad2, p-smad2/3, Smad2/3, Col1, αSMA, fibronectin, and vimentin and elevated the levels of Smad7 and Col3. In addition, miR-181a-5p was highly expressed in ADSC-Exo and bound to the 3'-untranslated region of Smad2. ADSC-Exo enriched with miR-181a-5p reduced collagen production in myofibroblasts and modulated the TGF-β pathway. CONCLUSIONS: ADSC-Exo promoted the proliferative and migratory capacities of myofibroblasts and inhibited collagen deposition and trans-differentiation of myofibroblasts in vitro. miR-181a-5p in exosomes targets Smad2 to regulate the TGF-β pathway in myofibroblasts. ADSC-Exo perform antifibrotic actions through the miR-181a-5p/Smad2 axis and may be a promising clinical treatment for OSF. BACKGROUND: Oral submucous fibrosis (OSF) is a chronic disease with carcinogenic tendency that poses a non-negligible threat to human health. Exosomes derived from human adipose mesenchymal stem cells (ADSC-Exo) reduces visceral and cutaneous fibroses, but their role in OSF has received little attention. The aim of this study was to investigate the effects of ADSC-Exo on OSF and elucidate the mechanism. METHODS: In brief, ADSCs were extracted from adipose tissues and subjected to flow cytometry and induction culture. Fibroblasts were isolated from human buccal mucosa and subjected to immunofluorescence. Myofibroblasts were obtained from fibroblasts induced by arecoline and identified. Immunofluorescence assay confirmed that myofibroblasts could take up ADSC-Exo. The effects of ADSC-Exo on the proliferative and migratory capacities of myofibroblasts were examined using the Cell Counting Kit-8 and scratch assay. Real-time quantitative polymerase chain reaction (qPCR) was performed to evaluate mothers against decapentaplegic homolog 2 (Smad2), Smad3, Smad7, collagen type 1 (Col1), Col3, alpha smooth muscle actin (α-SMA), fibronectin, and vimentin. Western blotting was performed to detect phospho (p)-Smad2, Smad2, p-Smad2/3, Smad2/3, Smad7, Col1, Col3, α-SMA, fibronectin, and vimentin. Furthermore, the dual-luciferase reporter assay was performed to prove that miR-181a-5p in ADSC-Exo directly inhibited the expression of Smad2 mRNA to regulate the transforming growth factor beta (TGF-β) pathway. We also performed qPCR and western blotting to verify the results. RESULTS: ADSC-Exo could promote the proliferation and migration of myofibroblasts, reduce the expressions of p-smad2, Smad2, p-smad2/3, Smad2/3, Col1, αSMA, fibronectin, and vimentin and elevated the levels of Smad7 and Col3. In addition, miR-181a-5p was highly expressed in ADSC-Exo and bound to the 3'-untranslated region of Smad2. ADSC-Exo enriched with miR-181a-5p reduced collagen production in myofibroblasts and modulated the TGF-β pathway. CONCLUSIONS: ADSC-Exo promoted the proliferative and migratory capacities of myofibroblasts and inhibited collagen deposition and trans-differentiation of myofibroblasts in vitro. miR-181a-5p in exosomes targets Smad2 to regulate the TGF-β pathway in myofibroblasts. ADSC-Exo perform antifibrotic actions through the miR-181a-5p/Smad2 axis and may be a promising clinical treatment for OSF.