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Mechanical and Tribological Properties of Short Basalt Fiber-reinforced Polyoxymethylene Composites
Chenghe Liu,Chunguang Long,Lei Chen,Junpeng Liu,Taishan Cao,Jian Zhang 한국고분자학회 2016 폴리머 Vol.40 No.6
In this paper, short basalt fiber-reinforced polyoxymethylene (POM) composites were prepared by melt blending and injection molding. The mechanical and tribological properties of the composites were studied by an orthogonal experiment. It was found that the optimal combination of fiber length 4 mm, fiber content 20 wt% and treated with KH550 would result in a comprehensive property which is 27.45% higher tensile strength, 9.65% higher impact strength and 18.11% higher flexural strength with compared to that of pure POM. But its tribological properties would be worse with the addition of the basalt fibers. After incorporating 10 wt% of polytetrafluoroethylene (PTFE) into the composites, the tribological properties of the composites was improved, closed to that of pure POM, with an insignificant decrease to their mechanical properties. Moreover, the morphology of fracture surfaces and worn surfaces evaluated by scanning electron microscopy showed good agreement with the results of the literature.
Impurity Behaviors under Wall Conditioning in HL-2A
Zhengying Cui,Chenghe Cui,Mingxu Wang,Ping Sun,Quanming Wang,Wei Li,Yudong Pan,Zeng Cao 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III
Impurities are one of the key issues of tokamak plasma research, as they are directly related to plasma quality and steady-state operation. The HL-2A device with two close divertor is the first divertor tokamak in China. It was successfully constructed in 2002 and has been operated for three 3 years up to now. In the 2004 campaign, siliconization as a wall conditioning was first done on the HL-2A tokamak by using glow discharge cleaning (GDC) with a gas mixture of SiH4 + He. The effects of siliconization on impurities and recycling are investigated, as well as the lifetime of siliconization, in this paper. The intensity of oxygen line is remarkably decreased after siliconization. Radiation of silicon line rapidly decreases shot by shot just after siliconization, but the effect of siliconization on the plasma properties is present all along and decreases gradually for a large amount of discharges. The effect of the siliconization can be maintained to about 180 discharges with similar discharge parameters.
One Million Percent Tunnel Magnetoresistance in a Magnetic van der Waals Heterostructure
Kim, Hyun Ho,Yang, Bowen,Patel, Tarun,Sfigakis, Francois,Li, Chenghe,Tian, Shangjie,Lei, Hechang,Tsen, Adam W. American Chemical Society 2018 NANO LETTERS Vol.18 No.8
<P>We report the observation of a very large negative magnetoresistance effect in a van der Waals tunnel junction incorporating a thin magnetic semiconductor, CrI<SUB>3</SUB>, as the active layer. At constant voltage bias, current increases by nearly one million percent upon application of a 2 T field. The effect arises from a change between antiparallel to parallel alignment of spins across the different CrI<SUB>3</SUB> layers. Our results elucidate the nature of the magnetic state in ultrathin CrI<SUB>3</SUB> and present new opportunities for spintronics based on two-dimensional materials.</P> [FIG OMISSION]</BR>
Li Lun,Sun Liuqiao,Liang Xiaoping,Ou Qian,Tan Xuying,Li Fangyuan,Lai Zhiwei,Ding Chenghe,Chen Hangjun,Yu Xinxue,Wu Qiongmei,Wei Jun,Wu Feng,Wang Lijun 한국영양학회 2023 Nutrition Research and Practice Vol.17 No.6
BACKGROUND/OBJECTIVES: Previous research has shown maternal betaine supplementation alleviates fetal-derived hepatic steatosis. Therefore, this study examined the anti-inflammatory effect of maternal betaine intake in offspring mice and its mechanism. MATERIALS/METHODS: Female C57BL/6J mice and their offspring were randomly divided into 3 groups according to the treatment received during gestation and lactation: control diet (CD), fatty liver disease (FLD), and fatty liver disease + 1% betaine (FLD-BET). The FLD group was given a high-fat diet and streptozotocin (HFD + STZ), and the FLD-BET group was treated with HFD + STZ + 1% betaine. After weaning, the offspring mice were given a normal diet for 5 weeks and then dissected to measure the relevant indexes. RESULTS: Compared to the CD group, the offspring mice in the FLD group revealed obvious hepatic steatosis and increased serum levels of alanine aminotransferase, interleukin (IL)-6, and tumor necrosis factor (TNF)-α; maternal betaine supplementation reversed these changes. The hepatic mRNA expression levels of IL-6, IL-18, and Caspase-1 were significantly higher in the FLD group than in the CD group. Maternal betaine supplementation reduced the expression of IL-1β, IL-6, IL-18, and apoptosis-associated speck-like protein containing C-terminal caspase recruitment domain (ASC). Maternal betaine supplementation also reversed the increasing protein expressions of nitric oxide dioxygenase-like receptor family pyrin domain containing 3 (NLRP3), ASC, Caspase-1, IL-1β, and IL-18 in offspring mice exposed to HFD + STZ. Maternal betaine supplementation decreased the homocysteine (Hcy) and s-adenosine homocysteine (SAH) levels significantly in the livers. Furthermore, the hepatic Hcy concentrations showed significant inverse relationships with the mRNA expression of TNF-α, NLRP3, ASC, and IL-18. The hepatic SAH concentration was inversely associated with the IL-1β mRNA expression. CONCLUSIONS: The lipotropic and anti-inflammatory effect of maternal betaine supplementation may be associated with the inhibition of NLRP3 inflammasome in the livers of the offspring mice.
Integrated multifunctional power converter for small electric vehicles
Cheng, He,Wang, Wuhui,Liu, Hailong,Yang, Shiyang The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.11
This paper proposes an integrated multifunctional power converter topology, where a traction battery charger (TBC), an auxiliary battery charger (ABC), and a motor drive converter (MDC) merge into an effective system. Traction battery charging, auxiliary battery charging, and motor driving operation modes can be realized by sharing power components. For the battery charging mode, a single-phase power supply charges the traction battery, and the circuit is capable of power factor correction (PFC) and active power decoupling (APD) (G2V mode). For the purpose of enhancing its charging power, the traction battery can also be connected to a three-phase power supply. For the battery discharging mode, the traction battery can feed energy back to a single-phase grid or a three-phase grid (V2G mode). When necessary, the traction battery can charge an auxiliary battery through a DC-DC converter (T2A mode). In the motor driving mode, the energy of the traction battery is used to drive a motor (T2M mode). Each of the charging modes can be implemented under the galvanic isolated condition. Power relays are used to switch the operating modes of the proposed topology.
Cheng, He,Chen, Hao,Xu, Shaohui,Yang, Shunyao The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6
Switched reluctance motor (SRM) is suitable for electric vehicle (EV) applications with the advantages of simple structure, good overload capability, and inherent fault-tolerance performance. The SRM dynamic simulation model is built based on torque, voltage, and flux linkage equations. The EV model is built on the basis of the analysis of forces acting on a vehicle. The entire speed range of the SRM drive is then divided into constant torque and constant power areas. The command torque of the motor drive system is given according to the accelerator pedal coefficient and motor operation areas. A novel adaptive variable angle control is proposed to avoid the switching chattering between the current chopping control and angle position control modes in SRM drives for EV applications. Finally, simulation analysis and experimental results are conducted to verify the accuracy of the proposed simulation model and control strategy.
Braking Torque Closed-Loop Control of Switched Reluctance Machines for Electric Vehicles
Cheng, He,Chen, Hao,Yang, Zhou,Huang, Weilong The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2
In order to promote the application of switched reluctance machines (SRM) in electric vehicles (EVs), the braking torque closed-loop control of a SRM is proposed. A hysteresis current regulator with the soft chopping mode is employed to reduce the switching frequency and switching loss. A torque estimator is designed to estimate the braking torque online and to achieve braking torque feedback. A feed-forward plus saturation compensation torque regulator is designed to decrease the dynamic response time and to improve the steady-state accuracy of the braking torque. The turn-on and turn-off angles are optimized by a genetic algorithm (GA) to reduce the braking torque ripple and to improve the braking energy feedback efficiency. Finally, a simulation model and an experimental platform are built. The simulation and experimental results demonstrate the correctness of the proposed control strategy.