A Topological Mapping Grinding Strategy for Structured Groove Surface with the Wire-Wound Grinding Wheel

Lyu Yushan,Wang Guoxun,Li Xingshan,Tang Chengzhi 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.7

The structured groove surface is one of the important surfaces in the field of reducing fluid drag or contact friction. The research on the manufacturing technology of the structured groove drag or friction reduction surface has important theoretical significance and practical value for the engineering application of the theoretical research results of the drag or friction reduction of the surface. In order to grind structured groove surface, a new topological mapping grinding strategy for structured groove surfaces is innovated based on topology. In order to verify the feasibility of this strategy, the topological features of the structured groove surface were firstly analyzed and modeled, and the topological feature parameters were extracted. Based on the feature parameters, the homeomorphic mapping equation of the grinding process is established, and according to the established equation, a circular arc-shaped helical structure grinding wheel with convex properties is designed, and the effect of grinding parameters on the structured groove surface is simulated and analyzed. Finally, a wire-wound structured grinding wheel with a diamond wire saw as the abrasive carrier was manufactured, and the experimental investigation of grinding structured groove surface was carried out. The results show that the innovative topology grinding strategy is feasible; the grinding wheel designed based on the topological features of the structured groove surface can realize the topological mapping grinding of the structured groove surface; the change of grinding parameters can lead to the change of the geometric size of the groove, but the topological properties remain unchanged.

Search for Constituents with Neurotrophic Factor Activity from Medicinal Plants and their Application to Drug Development

( Yasushi Ohizumi ),( Tohru Yamakuni ),( Yushan Li ) 한국응용약물학회 2004 Biomolecules & Therapeutics(구 응용약물학회지) Vol.12 No.4

Finite-time Controller Design for Four-wheel-steering of Electric Vehicle Driven by Four In-wheel Motors

Qing-Hua Meng,Zong-Yao Sun,Yushan Li 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

A smooth control method may do not obtain a desired convergence. On the other hand, a no-continuous method may cause a close-loop system to chatter. In order to avoid the aforementioned disadvantages, a non-smooth finite-time control method is proposed and applied on an active four-wheel-steering electric vehicle driven by four in-wheel motors to improve the safety and manoeuvrability in this paper. Based on an ideal electric vehicle steering tracking model, a non-smooth finite-time convergence controller is constructed for controlling the four wheels’ steering angles of an electric vehicle. The front wheel cornering stiffness, rear wheel cornering stiffness and external disturbance of a practical car are regarded as bounded uncertain parameters according to practical conditions. An A-class car model in the Carsim software is utilized to simulate the designed controller. The simulation results show that the controller based on finite-time convergence can track the ideal vehicle steering model better to obtain zero sideslip angle and expected yaw rate even when there exist perturbation of cornering stiffness and disturbance of lateral wind. It means the control system of the electric vehicle is robust with uncertainty. The simulation results also show that the non-smooth finite-time control method is better than the slide mode control method for the active four-wheel-steering system of the electric vehicle.

Variations of stress and deformation in the straightening process of turnout base plate

Hua Zhai,Yuanhao Wu,Xuepeng Liu,Qi Li,Yushan Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

Straightening technology is an important method to manufacture a high-speed railway turnout base plate with positioning blocks after welding. According to the straightening experiment results, the differences in straightening deformation and stress distribution were investigated between the turnout base plate and the counterpart flat plate under different loading conditions. The residual deformation of the counterpart flat plate is much higher than that of the base plate because of the welded positioning blocks. A theoretical model was presented to predict the straightening deformation variation. Finite element simulations were performed to simulate stress variation in the straightening process of the base plate. The stress concentration and residual stress distribution of the base plate were visually observed. The stress concentration factor changes gradually with the interface angle deflection at the welding area of the positioning block. The variation of dynamic stress concentration factor can be calculated and provide a certain theoretical reference to predict the straightening parameters.

Conceptual design of a MW heat pipe reactor

Wu Yunqin,Zheng Youqi,Chen Qichang,Li Jinming,Du Xianan,Wang Yongping,Tao Yushan 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.3

In recent years, unmanned underwater vehicles (UUV) have been vigorously developed, and with the continuous deepening of marine exploration, traditional energy can no longer meet the energy supply. Nuclear energy can achieve a huge and sustainable energy supply. The heat pipe reactor has no flow system and related auxiliary systems, and the supporting mechanical moving parts are greatly reduced, the noise is relatively small, and the system is simpler and more reliable. It is more favorable for the control of unmanned systems. The use of heat pipe reactors in unmanned underwater vehicles can meet the needs for highly compact, long-life, unmanned, highly reliable, ultra-quiet power supplies. In this paper, a heat pipe reactor scheme named UPR-S that can be applied to unmanned underwater vehicles is designed. The reactor core can provide 1 MW of thermal power, and it can operate at full power for 5 years. UPR-S has negative reactive feedback, it has inherent safety. The temperature and stress of the reactor are within the limits of the material, and the core safety can still be guaranteed when the two heat pipes are failed.

Effects of lactic acid bacteria and molasses on fermentation dynamics, structural and nonstructural carbohydrate composition and in vitro ruminal fermentation of rice straw silage

Jie Zhao,Zhihao Dong,Junfeng Li,Lei Chen,Yunfeng Bai,Yushan Jia,Tao Shao 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.6

Objective: This study was to evaluate the fermentation dynamics, structural and nonstructural carbohydrate composition and in vitro gas production of rice straw ensiled with lactic acid bacteria and molasses. Methods: Fresh rice straw was ensiled in 1-L laboratory silos with no additive control (C), Lactobacillus plantarum (L), molasses (M) and molasses+Lactobacillus plantarum (ML) for 6, 15, 30, and 60 days. After storage, the silages were subjected to microbial and chemical analyses as well as the further in vitro fermentation trial. Results: All additives increased lactic acid concentration, and reduced pH, dry matter (DM) loss and structural carbohydrate content relative to the control (p<0.05). The highest organic acid and residual sugar contents and lignocellulose reduction were observed in ML silage. L silage had the highest V-score with 88.10 followed by ML silage. L and ML silage improved in vitro DM digestibility as compared with other treatments, while in vitro neutral detergent fibre degradability (IVNDFD) was increased in M and ML silage (p<0.05). M silage significantly (p<0.05) increased propionic acid (PA) content and decreased butyric acid content and acetic acid/PA as well as 72-h cumulative gas production. Conclusion: The application of ML was effective for improving both the fermentation quality and in vitro digestibility of rice straw silage. Inclusion with molasses to rice straw could reduce in vitro ruminal gas production.

Effect of storage time and the level of formic acid on fermentation characteristics, epiphytic microflora, carbohydrate components and in vitro digestibility of rice straw silage

Zhao Jie,Wang Siran,Dong Zhihao,Li Junfeng,Jia Yushan,Shao Tao 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.6

Objective: The study aimed to evaluate the effect of storage time and formic acid (FA) on fermentation characteristics, epiphytic microflora, carbohydrate components and in vitro digestibility of rice straw silage. Methods: Fresh rice straw was ensiled with four levels of FA (0%, 0.2%, 0.4%, and 0.6% of fresh weight) for 3, 6, 9, 15, 30, and 60 d. At each time point, the silos were opened and sampled for chemical and microbial analyses. Meanwhile, the fresh and 60-d ensiled rice straw were further subjected to in vitro analyses. Results: The results showed that 0.2% and 0.6% FA both produced well-preserved silages with low pH value and undetected butyric acid, whereas it was converse for 0.4% FA. The populations of enterobacteria, yeasts, moulds and aerobic bacteria were suppressed by 0.2% and 0.6% FA, resulting in lower dry matter loss, ammonia nitrogen and ethanol content (p<0.05). The increase of FA linearly (p<0.001) decreased neutral detergent fibre and hemicellulose, linearly (p<0.001) increased residual water soluble carbohydrate, glucose, fructose and xylose. The in vitro gas production of rice straw was decreased by ensilage but the initial gas production rate was increased, and further improved by FA application (p<0.05). No obvious difference of FA application on in vitro digestibility of dry matter, neutral detergent fibre, and acid detergent fibre was observed (p>0.05). Conclusion: The 0.2% FA application level promoted lactic acid fermentation while 0.6% FA restricted all microbial fermentation of rice straw silages. Rice straw ensiled with 0.2% FA or 0.6% FA improved its nutrient preservation without affecting digestion, with the 0.6% FA level best. Objective: The study aimed to evaluate the effect of storage time and formic acid (FA) on fermentation characteristics, epiphytic microflora, carbohydrate components and <i>in vitro</i> digestibility of rice straw silage.Methods: Fresh rice straw was ensiled with four levels of FA (0%, 0.2%, 0.4%, and 0.6% of fresh weight) for 3, 6, 9, 15, 30, and 60 d. At each time point, the silos were opened and sampled for chemical and microbial analyses. Meanwhile, the fresh and 60-d ensiled rice straw were further subjected to <i>in vitro</i> analyses.Results: The results showed that 0.2% and 0.6% FA both produced well-preserved silages with low pH value and undetected butyric acid, whereas it was converse for 0.4% FA. The populations of enterobacteria, yeasts, moulds and aerobic bacteria were suppressed by 0.2% and 0.6% FA, resulting in lower dry matter loss, ammonia nitrogen and ethanol content (p<0.05). The increase of FA linearly (p<0.001) decreased neutral detergent fibre and hemicellulose, linearly (p<0.001) increased residual water soluble carbohydrate, glucose, fructose and xylose. The <i>in vitro</i> gas production of rice straw was decreased by ensilage but the initial gas production rate was increased, and further improved by FA application (p<0.05). No obvious difference of FA application on <i>in vitro</i> digestibility of dry matter, neutral detergent fibre, and acid detergent fibre was observed (p>0.05).Conclusion: The 0.2% FA application level promoted lactic acid fermentation while 0.6% FA restricted all microbial fermentation of rice straw silages. Rice straw ensiled with 0.2% FA or 0.6% FA improved its nutrient preservation without affecting digestion, with the 0.6% FA level best.

Stretchable Wire-Shaped Asymmetric Supercapacitors Based on Pristine and MnO₂ Coated Carbon Nanotube Fibers

Xu, Ping,Wei, Bingqing,Cao, Zeyuan,Zheng, Jie,Gong, Ke,Li, Faxue,Yu, Jianyong,Li, Qingwen,Lu, Weibang,Byun, Joon-Hyung,Kim, Byung-Sun,Yan, Yushan,Chou, Tsu-Wei American Chemical Society 2015 ACS NANO Vol.9 No.6

<P>While the emerging wire-shaped supercapacitors (WSS) have been demonstrated as promising energy storage devices to be implemented in smart textiles, challenges in achieving the combination of both high mechanical stretchability and excellent electrochemical performance still exist. Here, an asymmetric configuration is applied to the WSS, extending the potential window from 0.8 to 1.5 V, achieving tripled energy density and doubled power density compared to its asymmetric counterpart while accomplishing stretchability of up to 100% through the prestrainning-then-buckling approach. The stretchable asymmetric WSS constituted of MnO<SUB>2</SUB>/CNT hybrid fiber positive electrode, aerogel CNT fiber negative electrode and KOH-PVA electrolyte possesses a high specific capacitance of around 157.53 μF cm<SUP>–1</SUP> at 50 mV s<SUP>–1</SUP> and a high energy density varying from 17.26 to 46.59 nWh cm<SUP>–1</SUP> with the corresponding power density changing from 7.63 to 61.55 μW cm<SUP>–1</SUP>. Remarkably, a cyclic tensile strain of up to 100% exerts negligible effects on the electrochemical performance of the stretchable asymmetric WSS. Moreover, after 10 000 galvanostatic charge–discharge cycles, the specific capacitance retains over 99%, demonstrating a long cyclic stability.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-6/acsnano.5b01244/production/images/medium/nn-2015-012442_0007.gif'></P>