Extraction of visual texture features of seabed sediments using an SVDD approach

Li, Yan,Liu, Shijie,Zhu, Puqiang,Yu, Jiancheng,Li, Shuo Pergamon Press 2017 Ocean engineering Vol.142 No.-

<P><B>Abstract</B></P> <P>Perception of the seabed environment is an important capability of autonomous underwater vehicles. This paper focuses on defining and extracting robust texture features from visual images that lead to useful and practical automated identification of the types of seabed sediments. The visual texture features are described by using a gray-level co-occurrence matrix (GLCM) and fractal dimension, after which an unsupervised learning method, self-organizing map (SOM), is adopted to evaluate the validity of features descriptors on three types of seabed sediments. Subsequently, a kernel-based approach that exhibits robustness versus low numbers of high-dimensional samples, named support vector domain description (SVDD), is applied to classify the types of seabed sediments. In comparison with state-of-the-art classifiers, the experimental results demonstrated the effectiveness of the SVDD on the classification of seabed sediments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The visual images of seabed sediments are characterized by the texture features which are extracted based on the GLCM and fractal theory. </LI> <LI> A multi-class classification strategy for seabed sediments is proposed by adding a distance measure after SVDD implementation. </LI> <LI> The experimental results demonstrate that the proposed classification strategy is feasible in recognizing the type of seabed sediments. </LI> </UL> </P>

Delay Tolerant Packet Forwarding Algorithm Based on Location Estimation for Micro Aerial Vehicle Networks

( Shiji Li ),( Guyu Hu ),( Youwei Ding ),( Yun Zhou ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.3

In search and rescue mission, micro aerial vehicles (MAVs) are typically used to capture image and video from an aerial perspective and transfer the data to the ground station. Because of the power limitation, a cluster of MAVs are required for a large search area, hence an ad-hoc wireless network must be maintained to transfer data more conveniently and fast. However, the unstable link and the intermittent connectivity between the MAVs caused by MAVs’ movement may challenge the packet forwarding. This paper proposes a delay tolerant packet forwarding algorithm based on location estimation for MAV networks, called DTN_est algorithm. In the algorithm, ferrying MAVs are used to transmit data between MAVs and the ground station, and the locations of both searching MAVs and ferrying MAVs are estimated to compute the distances between the MAVs and destination. The MAV that is closest to the destination is selected greedy to forward packet. If a MAV cannot find the next hop MAV using the greedy strategy, the packets will be stored and re-forwarded once again in the next time slot. The experiment results show that the proposed DTN_est algorithm outperforms the typical DTN_geo algorithm in terms of packet delivery ratio and average routing hops.

Rapid Screen of IL-5/IL-5Rα Blocking Antibodies in the HEK293-IL-5Rα-CSF2RB Transfected Cell Line

Shijie Li,Fei Han,Chang Liu,Weiyan Dai,Wenfeng Ke,Yongqi Chen,Eric Fordjour,Yankun Yang,Zhonghu Bai 한국생물공학회 2023 Biotechnology and Bioprocess Engineering Vol.28 No.4

Interleukin-5 (IL-5) binding to interleukin-5 receptor subunit alpha (IL-5Rα) increases the number of eosinophils and enhances eosinophil activity. This leads to eosinophil tissue infiltration and damage to the lungs, ultimately resulting in exacerbation of asthma. Antibodies that block IL-5 binding to IL-5Rα are thought to play an important role in advanced asthma. Currently, key methods used to screen for targeted drugs are Surface Plasmon Resonance which is costly and anti-proliferation assays which are tedious and have a low signal-to-noise ratio. Here we describe a Fluorescence Activated Cell Sorting (FACS) assay, based on human embryonic kidney (HEK)- 293 cells with stable expression of IL-5Rα and the cytokine receptor common subunit beta (CSF2RB). Cells co-expressing IL-5Rα and CSF2RB had a 16% increase in the ability to bind IL-5 compared to cells expressing only IL-5Rα. The optimal concentration of IL-5 for the FACS assay was 0.1 μg/mL. The established FACS was used to screen anti IL-5 nanobodies and hybridoma supernatants for candidate antibodies that block the IL-5/IL-5α interaction. When compared to anti-proliferation assays, this method saved up to 90% of the assay time, offering the advantage of rapidity and accuracy in vitro. The assay described here provides a novel approach for rapid screening of IL-5/IL- 5Rα blocking antibodies in vitro to accelerate the development of drugs for asthma.

Learning-based Extended Dynamic Mode Decomposition for Addressing Path-following Problem of Underactuated Ships with Unknown Dynamics

Shijie Li,Ziqian Xu,Jialun Liu,Chengqi Xu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.12

Path-following techniques of ships have received a lot of attention in recent years, to promote future autonomous ships and develop advanced autopilots. This paper deals with the path-following problem of underactuated ships without having prior knowledge regarding the hydrodynamic coefficients and ship parameters. A novel data-driven control strategy that combines Koopman operator theory and extended dynamic mode decomposition (EDMD) method and integrates with a model predictive control (MPC) framework is proposed. It makes use of data collected from experiments to learn the Koopman eigenfunctions of unknown ship dynamics via supervised learning, which are utilized as the lifting functions in the EDMD method to build a linear, lifted state-space model. The identified linear model acts as the predictor in the designed MPC controller, and a line-of-sight (LOS) algorithm is introduced as the guidance law for path-following. Simulation results show that the prediction model could provide sufficient prediction accuracy, and that it can be combined with MPC to achieve good path-following performance in a computationally efficient way.

Study on the Network Structure of Equipment Manufacturing Industrial Clusters and an Empirical Case

Li Kai,Li Shijie 경성대학교 산업개발연구소 2005 산업혁신연구 Vol.21 No.1

Regulating the magnetic anisotropy by Hf thickness and heat treatment in Pt/Co/Hf films

Li Minghua,Zhang Shijie,Wang Shuanghai,Li Yongzeng,Liu Lu,Chen Yu,Shi Hui,Yu Guanghua 한국물리학회 2022 Current Applied Physics Vol.34 No.-

Pt/Co/Hf multilayers were prepared by magnetron sputtering, and the magnetic anisotropy was effectively regulated by Hf thickness and heat treatment in Pt/Co/Hf films. The interface microstructures were characterized. The influence of the interface microstructure on magnetic properties was studied. The results show that the magnetic anisotropy in Pt/Co/Hf films is closely related to the interface microstructure, which is influenced by Hf thickness and the heat treatment temperature. Microstructure analysis shows that after the Pt(3)/Co(1.5)/Hf (1) film is heat-treated, the CoOx content increases, more CoPt(111) forms, the interface is smoother and sharper, and the roughness of the Co/Hf interface decreases. Several factors work together to cause the magnetic anisotropy of the sample to change from in-plane magnetic anisotropy (IMA)to perpendicular magnetic anisotropy (PMA).

High-Performance Self-Expanding NiTi Stents Manufactured by Laser Powder Bed Fusion

Xiang Li,Shijie Hao,Baopeng Du,Bo Feng,Haohang Li,Ping Qiu,Bingmin Huang,Lishan Cui,Ying Yang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.5

Laser powder bed fusion (LPBF) is a promising technology for the manufacturing of customized medical implants, due tothe intrinsic potential in the fabrication of components with complex geometries. However, for the LPBF-produced vascularimplants, the dimensional accuracy, forming quality and surface finish are still unable to satisfy the medical requirements. This work provides a systematic study on dimensional accuracy control, relative density, surface polishing, shape memoryfunction, superelasticity property and deployment capability of LPBF-produced self-expanding NiTi stents, aiming at promotingtheir application in the biomedical field. The dimensional deviation of stent struts between designed prototype andas-melted products is reduced to 3% by applying laser beam compensation (LBC) strategy. Meanwhile, the study reveals thatthe LBC parameters have strong influence on the relative density of NiTi stents. 99.89% of relative density is achieved forLPBF-produced NiTi stent as the LBC value is optimized to 120 μm. The incompletely melted powders, balling and rippingstructures on the surface of NiTi stents are observed to exhibit different removal processes during electrochemical polishing. The surface roughness (Ra) of NiTi stent is decreased from 7.17 μm for as-melted stent to 0.34 μm for as-polished one. Basedon high relative density and surface quality, the stents exhibit excellent shape memory function and superelasticity propertyin the process of cyclic deformation. Finally, the deployment capability of the stents is assessed. The results confirm thatLPBF-produced NiTi stents can be successfully crimped and released during the deployment process.

A Group Link Prediction Framework Based on Graph Neural Networks

Shijie Luo,He Li,Jongtae Lim,Jaesoo Yoo 한국콘텐츠학회 2022 한국콘텐츠학회 ICCC 논문집 Vol.2022 No.12

Biodegradable Magnesium Alloy Stents as a Treatment for Vein Graft Restenosis

Yugang Li,Lei Wang,Shanshan Chen,Dan Yu,Weifeng Sun,Shijie Xin 연세대학교의과대학 2019 Yonsei medical journal Vol.60 No.5

Purpose: To explore the effects of biodegradable magnesium alloy stents (BMAS) on remodeling of vein graft (VG) anastomoticrestenosis. Materials and Methods: To establish a VG restenosis model, seventy two New Zealand rabbits were randomly divided into threegroups according to whether a stent was implanted in the graft vein or not. BMASs and 316L stainless steel stents were implantedin BMAS and 316L groups, respectively, while no stent was implanted in the no-treatment control group (NC group). Loss of lumendiameter in the graft vein was measured in all three groups. Upon harvesting VG segments to evaluate intimal proliferationand re-endothelization, the degradation and biological safety of the stents were observed to explore the effects of BMAS on VGremodeling. Results: Model establishment and stent implantation were successful. The BMAS reduced lumen loss, compared with the controlgroup (0.05±0.34 mm vs. 0.90±0.39 mm, p=0.001), in the early stage. The neointimal area was smaller in the BMAS group than the316L group after 4 months (4.96±0.66 mm2 vs. 6.80±0.69 mm2, p=0.017). Re-endothelialization in the BMAS group was better thanthat in the 316L group (p=0.001). Within 4 months, the BMAS had degraded, and the magnesium was converted to phosphorusand calcium. The support force of the BMAS began to reduce at 2–3 months after implantation, without significant toxic effects. Conclusion: BMAS promotes positive remodeling of VG anastomosis and has advantages over the conventional 316L stents in thetreatment of venous diseases.

Investigation on the stability of periodic motions of a flexible rotor-bearing system with two unbalanced disks

Chaofeng Li,Shihua Zhou,Shijie Jiang,Hexing Yu,Bang-chun Wen 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.7

The stability of periodic motion of a rotor-bearing system with two unbalanced disks is analyzed based on a multi-degree of freedom(M-DOF) finite element model. Nonlinear effects of supporting oil-film and inertia distributions as well as shearing effect are taken intoaccount. Focusing on the more realistic FE method to study the stability of nonlinear rotor-bearing system with the influence of the eccentricityphase, the stability calculation of the M-DOF FE model is done by using the combination of Shooting method and Newmarkmethod. Experiments with a rotor-bearing test rig (two disks on a shaft with two bearings) are then performed and results are presented. Itis found that typical instability characteristic is successfully produced. Through comparisons between calculated results and measurements,it is shown that the combination of Shooting method and Newmark method in studying the M-DOF rotor-bearing system is useful,especially for the complex rotor-bearing system. In addition, altering eccentricity phase of the two disks can significantly influence instabilitytype and speed. When the two disks are out of phase, the occurring of oil whip is restrained effectively. It is suggested that a carefulexamination should be made in modeling more complex non-linear rotor-bearing system.