Review on the research of contact parameters calibration of particle system

Xuewen Wang,Haozhou Ma,Bo Li,Tiejun Li,Rui Xia,Qingbao Bao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3

With the widespread application of the discrete element method, research on accurate simulation of particle systems has attracted significant attention. However, there is no accurate process for the parameter calibration of particle systems. Most calibrations use a direct measurement method or test-simulation combined calibration method. Both methods have their advantages and disadvantages. This study reviews the calibration of contact parameters of particle systems, introduces the main calibration methods of different contact parameters, and summarizes the advantages and disadvantages of two main measurement methods. For the parameter measurement of particle systems, the accurate representation of particle shape and the reasonable optimization of simulation time are still not perfect. Furthermore, the correction of parameters after calibration applied to subsequent simulation needs further discussion.

Design and simulation for a hydraulic actuated quadruped robot

Xuewen Rong,Yibin Li,Jiuhong Ruan,Bin Li 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4

This paper describes the mechanical configuration of a quadruped robot firstly. Each of the four legs consists of three rotary joints. All joints of the robot are actuated by linear hydraulic servo cylinders. Then it deduces the forward and inverse kinematic equations for four legs with D-H transformation matrices. Furthermore, it gives a composite foot trajectory composed of cubic curve and straight line,which greatly reduces the velocity and acceleration fluctuations of the torso along forward and vertical directions. Finally, dynamics cosimulation is given with MSC.ADAMS and MATLAB. The results of co-simulation provide important guidance to mechanism design and parameters preference for the linear hydraulic servo cylinders.

A drug delivery system constructed by a fusion peptide capturing exosomes targets to titanium implants accurately resulting the enhancement of osseointegration peri-implant

Li Xuewen,Liu Zihao,Xu Shendan,Ma Xinying,Zhao Zhezhe,Hu Han,Deng Jiayin,Peng Cheng,Wang Yonglan,Ma Shiqing 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Exosomes derived from bone marrow mesenchymal stem cells (BMSC-exos) have been shown triggering osteogenic differentiation and mineralization of MSCs, but exosomes administered via bolus injections are rapidly sequestered and cleared. Therefore, we considered the implant as a new organ of patient’s body and expected to find a method to treat implant with BMSC-exos in vivo directly.A fusion peptide (PEP), as a drug delivery system (DDS) which contained a titanium-binding peptide (TBP) possessing the ability to selectively bind to the titanium surface and another peptide CP05 being able to capture exosomes expertly, is constructed to modify the titanium surface.Both in vitro and in vivo experiments prove PEP retains the ability to bind titanium and exosome simultaneously, and the DDS gain the ability to target exosomes to titanium implants surface following enhancing osseointegration post-implantation. Moreover, the DDS constructed by exosomes of diverse origins shows the similar combination rate and efficiency of therapy.This drug delivery system demonstrates the concept that EXO-PEP system can offer an accurate and efficient therapy for treating implants with long-term effect.

SODIUM TANTALATE SPHERES PREPARED VIA AN ELECTROCHEMICAL PROCESS AND THEIR PHOTOELECTROCHEMICAL BEHAVIOR

XUEWEN WANG,LI ZHOU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.3

Photocatalytic activity can be improved through modified morphology and structure. Sodium tantalate (NaTaO3) as a semiconductor photocatalyst is extensively used for photocatalytic water splitting. A novel electrochemical route was developed for preparing NaTaO3 spheres. The method can easily and fast synthesize high pure phase NaTaO3 spheres at room temperature. The NaTaO3 sphere structure consists of a crystalline core and an amorphous shell. After a thermal treatment, the NaTaO3 spheres show an enhanced photoelectrochemical water splitting ability.

Differential Profile of Plasma Circular RNAs in Type 1 Diabetes Mellitus

Yangyang Li,Ying Zhou,Minghui Zhao,Jing Zou,Yuxiao Zhu,Xuewen Yuan,Qianqi Liu,Hanqing Cai,Cong-Qiu Chu,Yu Liu 대한당뇨병학회 2020 Diabetes and Metabolism Journal Vol.44 No.6

Background No currently available biomarkers or treatment regimens fully meet therapeutic needs of type 1 diabetes mellitus (T1DM). Circular RNA (circRNA) is a recently identified class of stable noncoding RNA that have been documented as potential biomarkers for various diseases. Our objective was to identify and analyze plasma circRNAs altered in T1DM. Methods We used microarray to screen differentially expressed plasma circRNAs in patients with new onset T1DM (n=3) and age-/gender-matched healthy controls (n=3). Then, we selected six candidates with highest fold-change and validated them by quantitative real-time polymerase chain reaction in independent human cohort samples (n=12). Bioinformatic tools were adopted to predict putative microRNAs (miRNAs) sponged by these validated circRNAs and their downstream messenger RNAs (mRNAs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to gain further insights into T1DM pathogenesis. Results We identified 68 differentially expressed circRNAs, with 61 and seven being up- and downregulated respectively. Four of the six selected candidates were successfully validated. Curations of their predicted interacting miRNAs revealed critical roles in inflammation and pathogenesis of autoimmune disorders. Functional relations were visualized by a circRNA-miRNA-mRNA network. GO and KEGG analyses identified multiple inflammation-related processes that could be potentially associated with T1DM pathogenesis, including cytokine-cytokine receptor interaction, inflammatory mediator regulation of transient receptor potential channels and leukocyte activation involved in immune response. Conclusion Our study report, for the first time, a profile of differentially expressed plasma circRNAs in new onset T1DM. Further in silico annotations and bioinformatics analyses supported future application of circRNAs as novel biomarkers of T1DM.

ELECTRONIC STRUCTURES AND TRANSPORT PROPERTIES OF SINGLE CRYSTALLINE GaN NANOTUBES

ENLING LI,LIPING HOU,ZHEN CUI,DANNA ZHAO,MANCANG LIU,XUEWEN WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.3

The electronic structures and transport properties of single crystalline GaN nanotubes with 0.92nm inner diameter and di®erent wall thicknesses of 0.08 nm, 0.26 nm and 0.54 nm are studied based on the generalized gradient approximation (GGA) of density functional theory (DFT) and the nonequilibrium green's function (NEGF). The research shows that (1) the three single crystalline GaN nanotubes have direct band gaps, decreasing with the increase of wall thickness;(2) the electronic density of state and electronic transmission spectra of two-probe system have their own pulse-type sharp peaks with almost the same location of electron energy; (3) under di®erent bias-voltages, two-probe systems of the single crystalline GaN nanotubes have the I?V properties which reveal that the single-wall GaN nanotube and the single-layer GaN nanotube are semiconducting and the double-layer GaN nanotube appears nearly metallic.

A free gait generation method for quadruped robots over rough terrains containing forbidden areas

Shuaishuai Zhang,Xuewen Rong,Yi-bin Li,Bin Li 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9

Planning a robust gait is one of the most basic aspects to enable a quadruped robot to walk stably on rough terrains. In this paper, wefocus on the scenario where a quadruped robot travelling on the rough terrains containing forbidden areas, and a free gait generationmethod for quadruped robot is proposed. Under the assumption that a set of the positions which can be selected as the foothold is given,the quadruped robot can select the swing foot sequence and choose the best foothold for the swing foot automatically. A body sway motionis included into the motion planning of the free gait to enlarge the stability margin of the robot. With the aid of the sway motion, thestability margin of the robot is no less than the minimum stability margin during the whole walking process. In order to guarantee thelocomotion continuity of the quadruped robot, a COG trajectory which has continuous velocity and acceleration profiles is automaticallygenerated. Moreover, the locomotion speed of the robot is improved by ensuring the kinematic margin of the selected swing foot to bezero just before this foot lift-off the ground. With the free gait generation method proposed in this paper, the robot can autonomouslynavigate through rough terrains as soon as possible on the condition that the robot has enough stability margin. The simulation resultsshow the correctness and effectiveness of the proposed method.

Design and control method of a hydraulic power unit for a wheel-legged robot

Zemin Cui,Xuewen Rong,Yibin Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4

For a hydraulic wheel-legged robot (WLR), it is essential to have a powerful and lightweight power supply. In this paper, a compact hydraulic power unit (HPU) is developed, and a control method to reduce the energy consumption of the robot is proposed. To achieve a high jump of the robot, an accumulator serves as an auxiliary oil source. To reduce the pressure loss caused by the throttle of the servo valve, we control the pressure of the system through load sensing. Simulation results showed that the power of the HPU using the accumulator could be amplified 3.3 times. The experimental results obtained through physical testing showed that the power consumption of the system using the load sensing mechanism was reduced by more than 50 %.

Random vibration fatigue life assessment and optimization of a train buffer beam considering welding residual stress

Chengji Mi,Jidong Liu,Xuewen Xiao,Wentai Li,Xiao Sun,Xingzu Ming,Changyan Tao,Ziyi Ren 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

The traditional fatigue design of accessories attached to a train body does not consider welding residual stress for fatigue life prediction of welded structures during the design stage, thereby resulting in insufficient fatigue strength for local welded parts. The power spectral density of random excitation caused by rail irregularity from American six-level spectrums was obtained in this paper. Through welding thermal elastoplastic theory combined with ellipsoid heat source model, a numerical simulation for welding residual stress production and distribution of a train buffer beam was conducted. In accordance with the coupling stress component, the fatigue performance of a train buffer beam under random loads was evaluated by the AA6082 welded joint S–N curve, whose lifetime did not satisfy design requirements. Then, the surrogate model of a train buffer beam for anti-fatigue optimization design was constructed based on the response surface method. The fatigue life of the optimized train buffer beam increased by two orders with the use of the genetic algorithm to find the optimal solution in global variables.

Description of Hymenobacter daejeonensis sp. nov., isolated from grass soil, based on multilocus sequence analysis of the 16S rRNA gene, gyrB and tuf genes

Jin, Long,Wu, Xuewen,Ko, So-Ra,Jin, Feng-Jie,Li, Taihua,Ahn, Chi-Yong,Oh, Hee-Mock,Lee, Hyung-Gwan Springer-Verlag 2018 Antonie van Leeuwenhoek Vol.111 No.12