An Improved Algorithm for Acoustic Radiation Force Impulse Imaging Based on Loupas Approach

YouXin,ShiDan,YinHao,LiuYu,Dongc Liu 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.12

With the purpose of solving the issue that there are errors in the traditional Loupas Algorithm used in ARFI and the effects of imaging are not as good as expected, this thesis will talk about an improved method to solve this proplem.Based on Loupas Algorithm, it is presented that we can get more accurate computing result of the displacement by changing the size of the sampling time windows and calculating the average speed according to the 2D autocorrelator.The method presented in this paper is aimed at doing computing refering to the tiny displacement caused by the push from ARFI and comparing between the displacement-time graph of the focus of the windows with different value.Finally,from these,people can know the most suitable value of the sampling time windows.Compared with the result of the experientunder traditional Loupas Algorithm,that of this experient has improved a lot.As a result,not only Elastographic Contrast-to-Noise Ratio has been improved,but also the image quality.

Graphene Oxide Nanoplatelets Grafted Jute Fibers Reinforced PP Composites

Youxin Chen,Wenzhe Chen,Weikang Liang,Qianting Wang,Yu Zhang,Jianjie Wang,Changxin Chen 한국섬유공학회 2020 Fibers and polymers Vol.21 No.12

To improve mechanical and thermal properties of jute fibers (JFs) reinforced polypropylene (PP) composites, asurface treatment method by grafting graphene oxide nanoplatelets (GONPs) onto JFs was developed. The GONPseffectively enhanced the interfacial adhesion between JFs and PP matrix via improving mechanical interlocking. The resultsshow that PP/JFs-KH570-GONPs composites had the significant improvement of 16.2 % and 12.4 % in tensile and flexuralstrength, respectively. And the thermal property of PP/JFs-Silane-GONPs composites was also improved after treatment. These high performance composites have the potential to be applied in many fields, such as the automotive industry,household products and so on.

Anticipated BSDEs driven by time-changed Lévy noises

Youxin Liu,,Yong Ren 한국통계학회 2015 Journal of the Korean Statistical Society Vol.44 No.3

In this paper, we discuss a class of anticipated backward stochastic differential equations (anticipated BSDEs, in short) driven by time-changed Lévy noises. We establish the existence and uniqueness of the solution. Moreover, we establish the duality relation between stochastic differential delay equations (SDDEs, in short) and anticipated BSDEs driven by time-changed Lévy noises.

일차보건에 통합된 산업보건사업의 시범보고 : 중국 동부지방의 소규모사업장에서의 예비조사의 개요

Liang Youxin,Gu xueqi 대한산업보건협회 1994 산업보건 Vol.72 No.-

Study of Harmonic Suppression of Ship Electric Propulsion Systems

Yifei Wang,Youxin Yuan,Jing Chen 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

This paper studies the harmonic characteristics of ship electric propulsion systems and their treatment methods. It also adopts effective measures to suppress and prevent ship power systems from affecting ship operation due to the serious damage caused by harmonics. Firstly, the harmonic characteristics of a ship electric propulsion system are reviewed and discussed. Secondly, aiming at problems such as resonant frequency and filter characteristics variations, resonance point migration, and unstable filtering performances in conventional passive filters, a method for fully tuning of a passive dynamic tunable filter (PDTF) is proposed to realize harmonic suppression. Thirdly, to address the problems of the uncontrollable inductance L of traditional air gap iron core reactors and the harmonics of power electronic impedance converters (PEICs), this paper proposes an electromagnetic coupling reactor with impedance transformation and harmonic suppression characteristics (ECRITHS), with the internal filter (IF) designed to suppress the harmonics generated by PEICs. The ECRITHS is characterized by both harmonic suppression and impedance change. Fourthly, the ECRITHS is investigated. This investigation includes the harmonic suppression characteristics and impedance transformation characteristics of the ECRITHS at the fundamental frequency, which shows the good performance of the ECRITHS. Simulation and experimental evaluations of the PDTF are carried out. Multiple PDTFs can be configured to realize multi-order simultaneous dynamic filtering, and can effectively eliminate the current harmonics of ship electric propulsion systems. This is done to reduce the total harmonic distortion (THD) of the supply currents to well below the 5% limit imposed by the IEEE-519 standard. The PDTF also can eliminate harmonic currents in different geographic places by using a low voltage distribution system. Finally, a detailed discussion is presented, with challenges and future implications discussed. The research results are intended to effectively eliminate the harmonics of ship electric power propulsion systems and to improve the power quality of ship power systems. This is of theoretical and practical significance for improving the power quality and power savings of ship power systems.

CARBON NANOTUBES/GRAPHENE THREE-DIMENSIONAL NETWORKS ARCHITECTURE LOADING WITH Ni AND ITS ADSORPTION PROPERTIES

BIN ZENG,YOUXIN LUO,QIYUAN LIU,WUJUN ZENG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.2

The composite of carbon nanotubes/graphene networks loaded-Ni (CNTs/GR-Ni) were suc-cessfully synthesized by spray drying and post-calcinating method for the ¯rst time. The syn-thesized products were systematically studied by X-ray di®raction, scanning electron microscopyand transmission electron microscopy. The result showed the hybrid of CNTs and graphenecomposed the 3D network structure and Ni nanoparticles were attaching on their surface. Adsorption performance evidenced that the obtained nanocomposite possessed high adsorptione±ciency and excellent separation property.

Synthesis and characterization of polypyrrole doped by cage silsesquioxane with carboxyl groups

Gang Shi,Youxin Che,Luyan Wu,Yao Rong,Caihua Ni 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

Cage silsesquioxane with carboxyl groups (POSS-COOH) was successfully synthesized, after which it was added to polypyrrole (PPy) as a dopant to produce the doped PPy (PPy/POSS-COOH) solution. The PPy/POSSCOOH composites were characterized by FTIR (Fourier transformation infrared spectroscopy), SEM (Scanning electron microscopy), TGA (Thermo-gravimetric analysis), CV (Cyclic voltammetry) and RL (Reflection loss). Compared to PPy without POSS-COOH (un-PPy), the conductivity of PPy/POSS-COOH composites could be improved dramatically, reaching up to 0.850 S/cm at 25 oC. Under N2 atmosphere, the residual rate of PPy/POSS-COOH was 68% at 700 oC, 14% higher than the one of un-PPy. Meanwhile, PPy/POSS-COOH had a reflection loss below −8 dB over 9.35 to 11.20GHz, with a minimum value of −10.32 dB at 10.54 GHz, thus demonstrating higher microwave absorption than un-PPy. This method may provide a facile route to produce doped conducting polymers with POSS-COOH.

Study of Harmonic Suppression of Ship Electric Propulsion Systems

Wang, Yifei,Yuan, Youxin,Chen, Jing The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

This paper studies the harmonic characteristics of ship electric propulsion systems and their treatment methods. It also adopts effective measures to suppress and prevent ship power systems from affecting ship operation due to the serious damage caused by harmonics. Firstly, the harmonic characteristics of a ship electric propulsion system are reviewed and discussed. Secondly, aiming at problems such as resonant frequency and filter characteristics variations, resonance point migration, and unstable filtering performances in conventional passive filters, a method for fully tuning of a passive dynamic tunable filter (PDTF) is proposed to realize harmonic suppression. Thirdly, to address the problems of the uncontrollable inductance L of traditional air gap iron core reactors and the harmonics of power electronic impedance converters (PEICs), this paper proposes an electromagnetic coupling reactor with impedance transformation and harmonic suppression characteristics (ECRITHS), with the internal filter (IF) designed to suppress the harmonics generated by PEICs. The ECRITHS is characterized by both harmonic suppression and impedance change. Fourthly, the ECRITHS is investigated. This investigation includes the harmonic suppression characteristics and impedance transformation characteristics of the ECRITHS at the fundamental frequency, which shows the good performance of the ECRITHS. Simulation and experimental evaluations of the PDTF are carried out. Multiple PDTFs can be configured to realize multi-order simultaneous dynamic filtering, and can effectively eliminate the current harmonics of ship electric propulsion systems. This is done to reduce the total harmonic distortion (THD) of the supply currents to well below the 5% limit imposed by the IEEE-519 standard. The PDTF also can eliminate harmonic currents in different geographic places by using a low voltage distribution system. Finally, a detailed discussion is presented, with challenges and future implications discussed. The research results are intended to effectively eliminate the harmonics of ship electric power propulsion systems and to improve the power quality of ship power systems. This is of theoretical and practical significance for improving the power quality and power savings of ship power systems.

Polyurethane Membrane with Temperature- and pH-Controllable Permeability for Amino-Acids

Hu Zhou,Ruiping Xun,Kejian Wu,Zhihua Zhou,Bin Yu,Youxin Tang,Ning Li 한국고분자학회 2015 Macromolecular Research Vol.23 No.1

This work was focused on the investigation of the temperature- and pH-responsive polyurethane (PU)membranes and their permeability to amino-acids in response to environmental stimuli. The PU membrane wasprepared from a wet phase inversion method and a two-step solution polymerization from polycaprolactone diols(PCL), 4,4′-diphenylmethane diisocyanate (MDI), dimethylol propionic acid (DMPA), etc. The chemical structure,phase state, morphology and surface wettability of the membrane were characterized with Fourier transform infrared(FTIR) spectrometer, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and contactangle tester, respectively. The temperature and pH responses of the membrane were investigated by means of anamino-acid permeate experiment. The L-phenylalanine (L-Phe) was chosen as model amino-acids. The permeation of theL-Phe was measured using a dead-end flow filtration at varied temperatures and pH, and characterized by the permeateflux (J) and rejection coefficient (R). J of the L-Phe across the PU membrane increased with increasingtemperature and showed a sharp increase when temperature was raised to the crystalline melting temperature (Tm)of the soft segment of PU, while decreased with increasing pH and having a sharp decrease when pH reached thedissociation constant (pKa) of DMPA contained in PU macromolecules. While, the R behavior of L-Phe was justopposite from the results of J, which decreased with increasing temperature and increased with increasing pH,also showing the temperature and pH responses. Hopefully, the PU membrane with temperature- and pH-controllablepermeability has promising prospects in water treatment, membrane separation, drug delivery system, etc.

Evaluation of the YOLO models for discrimination of the alfalfa pollinating bee species

Zhang Chuan-Jie,Liu Teng,Wang Jinxu,Zhai Danlan,Zhang Youxin,Gao Yang,Wu Hui-Zhen,Yu Jialin,Chen Min 한국응용곤충학회 2024 Journal of Asia-Pacific Entomology Vol.27 No.1

Identifying insect pollinators and their roles in mediating pollen flow is critical to understand the potential gene flow risks of insect pollination-dependent crop species, such as alfalfa. This study was conducted to evaluate and compare the feasibility of You Only Look Once (YOLO) version 3 (YOLOv3), YOLOv5, YOLOv7, and YOLO Representation (YOLOR) to discriminate the three most common alfalfa pollinating bee species, including honeybee, bumblebee, and leafcutting bee. The metrics comparison results showed YOLOv3 and YOLOv5 out performed YOLOv7 and YOLOR regarding model precision, recall, F 1 score, and mAP50 values. YOLOv3 and YOLOv5 could successfully discriminate the three different bee species with an accuracy of almost 100% (99.9%, 99.8%, and 100% accuracy for honeybee, bumblebee, and leafcutting bee for the two models, respectively). Comparatively, YOLOv7 could discriminate honeybee with an accuracy of 95% but was more likely to mistakenly discriminate bumblebee and leafcutting bee due to the relatively lower discriminating accuracy (87.3% and 66.2%, respectively). While the values of determined parameters for YOLOR were lower than YOLOv3 and YOLOv5, the higher precision (0.99680) along with recall (0.98721), F 1 (0.99198), mAP50 (0.99323), and mAP50-100 (0.89076) values indicate that this model could be able to obtain a favorable performance in discriminating the three bee species. In summary, the proposed method in this study has the potential for identifying the alfalfa pollinating bee species, studying the bees’ flower-visiting behaviors, evaluating the risks of insect-mediated pollen flow, and thus contributing to the management of genetically engineered (GE) alfalfa transgene flow.