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.

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.

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.-

Sliding Mode Robust Control of Hydraulic Drive Unit of Hydraulic Quadruped Robot

Rui Zhu,Qingjun Yang,Yudong Liu,Rizhi Dong,Chunli Jiang,Jiaxing Song 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4

This paper focuses on the position control of the quadruped robot hydraulic drive unit (HDU). The proposed control strategy has the advantages of excellent output tracking performance, strong robustness, no chattering and low computational complexity. HDU has the characteristics of nonlinearity and parameter uncertainty, coupled with unpredictable external interference, which makes it difficult to achieve precise position control. In this paper, we first establish the mathematical model of the HDU based on the actual parameters and obtain the state space of the system. Through the pole placement, the simplified system can easily achieve the expected control goal. Then, the state equation of the error system is constructed, and the nonlinearity, parameter uncertainty and external interference of the HDU are summarized as the matched and unmatched uncertainties of the system. The integral sliding mode control (ISMC) is used to derive the control law, and the response characteristics of the system when pole placement and state feedback H∞ control are used for the nominal control are compared. It can be concluded that the system with state feedback H∞ control for nominal control has stronger robustness and can resist the unmatched uncertainties. Finally, the control law of the simplified system is used as feedforward and combined with the ISMC of the error system, the output tracking control framework of the HDU is proposed. Simulations and experiments show that the proposed control method has excellent tracking performance and strong robustness.

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.

Therapeutic Regimens and Prognostic Factors of Brain Metastatic Cancers

Song, Wen-Guang,Wang, Yi-Feng,Wang, Rui-Lin,Qu, Yin-E,Zhang, Zhi,Li, Guo-Zhong,Xiao, Ying,Fang, Fang,Chen, Hong Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.2

Objective: This work aims to investigate the therapeutic regimen of brain metastatic cancers and the relationship between clinical features and prognosis. Methods: Clinical data of 184 patients with brain metastatic cancers were collected and analysed for the relationship between survival time and age, gender, primary diseases, quantity of brain metastatic foci, their position, extra cranial lesions, and therapeutic regimens. Results: The average age of onset was 59.1 years old. The median survival time (MST) was 15.0 months, and the patients with breast cancer as the primary disease had the longest survival time. Females had a longer survival time than males. Patients with meningeal metastasis had extremely short survival time. Those with less than 3 brain metastatic foci survived longer than patients with more than 3. The MST of patients receiving radiotherapy only and the patients receiving chemotherapy only were all 10.0 months while the MST of patients receiving combination therapy was 16.0 months. Multiple COX regression analysis demonstrated that gender, primary diseases, and quantity of brain metastatic foci were independent prognostic factors for brain metastatic cancers. Conclusions: Chemotherapy is as important as radiotherapy in the treatment of brain metastatic cancer. Combination therapy is the best treatment mode. Male gender, brain metastatic cancers originating in the gastrointestinal tract, more than 3 metastatic foci, and involvement of meninges indicate a worse prognosis.

Assessing the contribution of Research System and CG Genetic materials to the total factor productivity of rice in China

( Rui Fa Hu ),( Ji Kun Huang ),( Song Qing Jin ),( Scott Rozelle ) 한국농촌경제연구원 2000 Journal of Rural Development Vol.23 No.1

The overall goal of our paper is to create a framework for studying the impact of national investment into research and extension in China and to measure the impact that such investments have had on creating productivity-increasing technology. Our purpose is to provide more convincing measures of the impacts of crop-specific investment in national research programs and the import of materials from the CG system. Specifically, we use a new measure of seed technology to track the changes in the quantity and quality of genetic resources in China`s major rice producing provinces from 1982 to 1995. We find that new technology has provided almost all of the growth of China`s TFP of rice. The International Rice Research Institute has supplied an important part of China`s rice germplasm and positively contributed to the health of Chin0a`s rice sector.

Experimental Study on the Properties of Phosphate-Based Materials for Rapid Repair of Concrete Cracks

Rui Wang,Anxiang Song,Xiang Chen,Yuanchen Guo,Xue Wang,Yan Sun,Miao Tian 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.5

This article studies rapid repair materials by mainly carrying out macro- and micro-performanceimpact tests. The static volumetric method was used to conduct pore volume-aperture analysis and prove the impact of the durability and repair performance of materials. The results show that 1) material impermeability can be effectively improved by increasing the ratio of active ingredients A:B and reducing the water-to-binder ratio. Adding an appropriate amount of fine aggregate can enable one to adjust the microstructure of the repair material, improve the compactness of the material, and effectively improve the impermeability. 2) An increase in the proportion of active ingredient A, water-binder ratio, sand-cement ratio and fly ash content will reduce the self-shrinkage of the specimen; with increasing NS and silica fume content, shrinkage increases. 3) Through analysis of pore size and pore volume, the total pore volume of the repair material is found to be reduced by 16.0% compared with cement mortar. Within a pore diameter range of 2.00 − 10.00 nm, the volume of the repair material increases by 78.9% compared to that for cement mortar. The total volume of the mesopores (2 − 50 nm) in the repair material accounts for 87.7% of the total volume, and the total volume of the mesopores in the cement mortar accounts for 81.23% of the total volume, which further illustrates the excellent macroscopic properties of the repair material.