Molecular Dynamics Simulation to Investigate the Rake Angle Effects on Nanometric Cutting of Single Crystal Ni3Al

Rui-cheng Feng,Yong-nian Qi,Zong-xiao Zhu,Wen-yuan Song,Hai-yan Li,Mao-mao Wang,Zhi-yuan Rui,Feng-shou Gu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.4

Molecular dynamics, an eff ective method to gain an insight into nanometric behaviour of materials, was employed to studythe nano-cutting behaviour of single crystal Ni 3 Al in nanometric scale. In this paper, comparisons were made for compressive/tensile stress, subsurface damage and surface roughness with three rake angles of a diamond tool. Subsurface damage waspartitioned by region and studied with work hardening in detail. A model for precise characterization of surface roughnesswas established with consideration of local surface fl uctuation. Simulation results showed that the chip thickness increasedas rake angle changed from negative to positive, and the boundary formed between tensile and compressive stress was inconsistent with the glide direction of stacking fault. Subsurface damage decreased as the increase of rake angle, and regularglide planes of stacking faults were found in front of the cutting tool. Further, the pinned dissociated 1/2 < 110 > superpartialdislocation with anti-phase boundary was demonstrated. The model was tested and characterized by implanted pits onperfect surface. Results showed that surface roughness can be well characterized, and an evident discrepancy was observedamong three rake angles, especially for 30° rake angle, which showed an distinct smooth surface compared with the others.

Experimental and numerical investigation on the pressure pulsation in reactor coolant pumps under different inflow conditions

Huang Song,Song Yu,Yin Junlian,Xu Rui,Wang Dezhong 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.4

A reactor coolant pump (RCP) is essential for transporting coolant in the primary loop of pressurized water reactors. In the advanced passive reactor, the absence of a long pipeline between the steam generator and RCP serves as a transition section, resulting in a non-uniform flow field at the pump inlet. Therefore, the characteristics of the pump should be investigated under non-uniform flow to determine its influence on the pump. In this study, the pressure pulsation characteristics were examined in the time and frequency domains, and the sources of low-frequency and high-amplitude signals were analyzed using wavelet coherence analysis and numerical simulation. From computational fluid dynamics (CFD) results, non-uniform inflow has a great effect on the flow structures in the pump's inlet. The pressure pulsation in the pump at the rated flow increased by 78–128.7% under the non-uniform inflow condition in comparison with that observed under the uniform inflow condition. Furthermore, a low-frequency signal with a high amplitude was observed, whose energy increased significantly under non-uniform flow. The wavelet coherence and CFD analysis verified that the source of this signal was the low-frequency pulsating vortex under the steam generator.

An Improved Image Registration Based on Nonsubsampled Contourlet Transform and Zernike Moments

Rui Ding,Ziyan Song,Jin Tang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.6

Feature-based registration is an effective and most widely used image registration method currently. It includes three critical steps, feature extraction, feature matching and transformation parameters estimation. This paper mainly explores the first two steps. In one of Chahira Serief’s paper about image registration, feature points extraction based on nonsubsampled contourlet transform (NSCT) was proposed and feature points matching based on Zernike moments was adopted. The registration accuracy and robustness of his algorithm are acceptable, but it can still be improved. In this paper, an improved scheme of this registration algorithm is proposed. The rotation invariance of NSCT-based feature points extraction is improved, which is beneficial to extract homologous feature points. And the reliability and effectiveness of Zernike moments-based feature points matching are improved, which can improve the matching accuracy. The improved registration algorithm can realize registration of images related by larger scaling, rotation and translation transformation. The simulation results show that the registration robustness is further improved, and the registration accuracy is still high.

MODELING ON RENEWABLE ENERGY INTEGRATION INTO MICROGRID

Rui Huang,Wenbo Shi,Daoyuan Yao,Chi-Cheng Chu,Rajit Gadh,Yu-jin Song,Yoon-dong Sung 한국신재생에너지학회 2015 AFORE Vol.2015 No.11

The Influence of Vegetation Variation on Northeast Asian Dust Activity

Rui Mao,허창회,Song Feng,Dao-Yi Gong,Yaping Shao 한국기상학회 2013 Asia-Pacific Journal of Atmospheric Sciences Vol.49 No.1

In this study, we investigate the influence of vegetation variations on dust activity (dust load, dust transport in the troposphere,and dust weather frequency) over Northeast Asia during springtime. By using the Integrated Wind Erosion Modeling System,two model experiments are run over four-month periods, from February 1 to May 31, for each year from 1982 to 2006; one experiment uses the observed atmospheric conditions and vegetation (OBS), and the other uses the specified atmospheric conditions in 2006 and the observed vegetation (CTRL). Comparison of the two model experiments reveals that there are sensitive regions in southeastern Mongolia and central northern China, in which vegetation has a large potential to influence dust activity due to both the high dust emission rate and large variations in vegetation coverage. Over these sensitive regions,vegetation effectively lessens dust loads on interannual and interdecadal timescales; dust load is decreased by 2864 μg m−2 for an increment of 0.1 in the normalized difference vegetation index (NDVI). Vegetation increase in the sensitive areas also reduces two major branches of dust transports in the low troposphere; one stretches from eastern Mongolia to regions northeastward, and the other flows across the south of northeastern China to Korea. In addition to dust loads and transports, vegetation increase in the sensitive areas evidently decreases dust storm frequency and blowing dust frequency, but it exerts a weak influence on the floating dust frequency. In the sensitive regions, as NDVI increases by 0.1, dust storms, blowing dust,and floating dust decrease by 4.0 days/spring, 1.5 days/spring, and 0.2 days/spring, respectively. In summary, vegetation variations in southeastern Mongolia and central northern China have considerable impact on northeast Asian dust during springtime.

Pollen record of the centennial climate changes during 9-7 cal ka BP in the Changjiang (Yangtze) River Delta plain, China

Song, Bing,Li, Zhen,Lu, Houyuan,Mao, Limi,Saito, Yoshiki,Yi, Sangheon,Lim, Jaesoo,Li, Zhen,Lu, Anqing,Sha, Longbing,Zhou, Rui,Zuo, Xinxin,Pospelova, Vera Cambridge University Press 2017 Quaternary research Vol.87 No.2

<B>Abstract</B><P>We reconstructed the centennial climate changes for the period of 9-7 cal ka BP in the upper region of the Changjiang (Yangtze) River Delta plain. A general warming and wetting trend from 8560 to 7220 cal yr BP was indicated by the decrease in <I>Quercus</I> (deciduous) and increases in <I>Quercus</I> (evergreen), <I>Pinus</I>, and Polypodiaceae spores. However, there were several brief climate fluctuations. A notable palynological change, from regional assemblages dominated by arboreal pollen to local assemblages mainly consisting of nonarboreal pollen, reflects climate fluctuations. The key indices of <I>Quercus</I> (deciduous), <I>Pinus</I>, herbs, fern spores, and palynological concentrations showed similar signs of centennial climate fluctuations. We suggest that the climate changes of the Dongge Cave and Yangtze River Delta regions were mainly affected by the East Asian summer monsoon (EASM) during the period of 9-7 cal ka BP. The general warming trend may be associated with an intensified EASM, and solar activity may be one of the important factors driving the centennial climate changes. The ~8.2 ka event was also recorded in the Yangtze River Delta region, which suggests that there was a close relationship between the EASM and Greenland climate during the early Holocene.</P>

A Novel Design of Compact Low-Pass Filter and Its Equivalent Circuit Model

Rui LI,Dong-ll KIM,Chang-Mook CHOl,Young-Man SONG 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.2006 No.-

A novel design of compact low-pass filter based on microstrip structure and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of lowpass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

Ultrathin Trilayer Assemblies as Long-Lived Barriers against Water and Ion Penetration in Flexible Bioelectronic Systems

Song, Enming,Li, Rui,Jin, Xin,Du, Haina,Huang, Yuming,Zhang, Jize,Xia, Yu,Fang, Hui,Lee, Yoon Kyeung,Yu, Ki Jun,Chang, Jan-Kai,Mei, Yongfeng,Alam, Muhammad A.,Huang, Yonggang,Rogers, John A. American Chemical Society 2018 ACS NANO Vol.12 No.10

<P>Biomedical implants that incorporate active electronics and offer the ability to operate in a safe, stable fashion for long periods of time must incorporate defect-free layers as barriers to biofluid penetration. This paper reports an engineered material approach to this challenge that combines ultrathin, physically transferred films of silicon dioxide (t-SiO<SUB>2</SUB>) thermally grown on silicon wafers, with layers of hafnium oxide (HfO<SUB>2</SUB>) formed by atomic layer deposition and coatings of parylene (Parylene C) created by chemical vapor deposition, as a dual-sided encapsulation structure for flexible bioelectronic systems. Accelerated aging tests on passive/active components in platforms that incorporate active, silicon-based transistors suggest that this trilayer construct can serve as a robust, long-lived, defect-free barrier to phosphate-buffered saline (PBS) solution at a physiological pH of 7.4. Reactive diffusion modeling and systematic immersion experiments highlight fundamental aspects of water diffusion and hydrolysis behaviors, with results that suggest lifetimes of many decades at physiological conditions. A combination of ion-diffusion tests under continuous electrical bias, measurements of elemental concentration profiles, and temperature-dependent simulations reveals that this encapsulation strategy can also block transport of ions that would otherwise degrade the performance of the underlying electronics. These findings suggest broad utility of this trilayer assembly as a reliable encapsulation strategy for the most demanding applications in chronic biomedical implants and high-performance flexible bioelectronic systems.</P> [FIG OMISSION]</BR>

DESIGN AND IMPLEMENTATION OF COMMUNICATION ARCHITECTURE IN A DISTRIBUTED ENERGY RESOURCE SYSTEM USING IEC 61850 STANDARD

Rui Huang,Wenbo Shi,Daoyuan Yao,Chi-Cheng Chu,Rajit Gadh,Yu-jin Song,Yoon-dong Sung 한국신재생에너지학회 2014 AFORE Vol.2014 No.-

Research and Improvement on Active Compliance Control of Hydraulic Quadruped Robot

Rui Zhu,Qingjun Yang,Jiaxing Song,Shangru Yang,Yudong Liu,Qi Mao 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.5

This paper focuses on active compliance control of hydraulic quadruped robot, especially the analysis of the inner-loop of the coupled system. Current researches on active compliance control regard the bandwidth of the inner loop of the system as infinite, while ignoring that the extra-load will cause the inner-loop response characteristics to deteriorate when the leg is in the stance phase. In this work, we first briefly introduced the structure of the robot, and its kinematics and dynamics are analyzed. Next, the robot’s active compliance control framework is established, and the inner-loop two-cylinder coupling system is analyzed in depth. It can be concluded that the existence of low frequency poles in the system is the main reason for the poor response characteristics. Then through the analysis of the state equation and transfer function matrix of the multi-input multi-output system, we show that the equivalent hydraulic spring stiffness (EHSS) is the main factor affecting the zero-pole distribution. Furthermore, we optimize the structure to increase the EHSS to improve the response characteristics of the system. Finally, the co-simulation platform and single-leg experiment bench are introduced. The simulation and experimental results show that the response speed of the inner-loop control is significantly improved after optimization, and the robot with active compliance control strategies can significantly reduce the impact of the foot.