Spall-Velocity Reduction in Double-Pulse Impact on Tin Microdroplets

This paper deals with a new state-constrained control (SCC) system of vehicle, which includes a multi-layer controller, in order to ensure the vehicle’s lateral stability and steering performance under complex environment. In this system, a new constraint control strategy with input and state constraints is applied to calculate the steady-state yaw moment. It ensures the vehicle lateral stability by tracking the desired yaw rate value and limiting the allowable range of the side slip. Through the linkage of the three-layer controller, the tire load is optimized and achieve minimal vehicle velocity reduction. The seven-degree-of-freedom (7-DOF) simulation model was established and simulated in MATLAB to evaluate the effect of the proposed controller. Through the analysis of the simulation results, compared with the traditional ESC and integrated control, it not only solves the problem of obvious velocity reduction, but also solves the problem of high cost and high hardware requirements in integrated control. The simulation results show that designed control system has better performance of path tracking and driving state, which is closer to the desired value. Through hardware-in-the-loop (HIL) practical experiments in two typical driving conditions, the effectiveness of the above proposed control system is further verified, which can improve the lateral stability and maneuverability of the vehicle.

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A Novel Gate Drive Circuit for Suppressing Turn-on Oscillation of Non-Kelvin Packaged SiC MOSFET

Energies ◽

10.3390/en14092449 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2449

Author(s):

Hongyan Zhao ◽

Jiangui Chen ◽

Yan Li ◽

Fei Lin

Keyword(s):

Thermal Conductivity ◽

Breakdown Voltage ◽

Basic Principle ◽

Double Pulse ◽

Experimental Results ◽

Switching Frequency ◽

Turn On ◽

Proof Testing ◽

Gate Driver ◽

Drive Circuit

Compared with a silicon MOSFET device, the SiC MOSFET has many benefits, such as higher breakdown voltage, faster action speed and better thermal conductivity. These advantages enable the SiC MOSFET to operate at higher switching frequencies, while, as the switching frequency increases, the turn-on loss accounts for most of the loss. This characteristic severely limits the applications of the SiC MOSFET at higher switching frequencies. Accordingly, an SRD-type drive circuit for a SiC MOSFET is proposed in this paper. The proposed SRD-type drive circuit can suppress the turn-on oscillation of a non-Kelvin packaged SiC MOSFET to ensure that the SiC MOSFET can work at a faster turn-on speed with a lower turn-on loss. In this paper, the basic principle of the proposed SRD-type drive circuit is analyzed, and a double pulse platform is established. For the purpose of proof-testing the performance of the presented SRD-type drive circuit, comparisons and experimental verifications between the traditional gate driver and the proposed SRD-type drive circuit were conducted. Our experimental results finally demonstrate the feasibility and effectiveness of the proposed SRD-type drive circuit.

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Dirac Fermions: Fermi Velocity Reduction of Dirac Fermions around the Brillouin Zone Center in In 2 Se 3 –Bilayer Graphene Heterostructures (Adv. Mater. 17/2021)

Advanced Materials ◽

10.1002/adma.202170129 ◽

2021 ◽

Vol 33 (17) ◽

pp. 2170129

Author(s):

Zhenyu Wang ◽

Zhanyang Hao ◽

Yayun Yu ◽

Yuan Wang ◽

Shiv Kumar ◽

...

Keyword(s):

Brillouin Zone ◽

Bilayer Graphene ◽

Fermi Velocity ◽

Dirac Fermions ◽

Velocity Reduction ◽

Brillouin Zone Center

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Influence of Duty Ratio and Current Mode on Robot 316L Stainless Steel Arc Additive Manufacturing

Metals ◽

10.3390/met11030508 ◽

2021 ◽

Vol 11 (3) ◽

pp. 508

Author(s):

Ping Yao ◽

Hongyan Lin ◽

Wei Wu ◽

Heqing Tang

Keyword(s):

Stainless Steel ◽

Additive Manufacturing ◽

Heat Input ◽

Low Frequency ◽

Single Pulse ◽

Pulse Mode ◽

Double Pulse ◽

Duty Ratio ◽

Utilization Rate ◽

Specimen Height

Wire and arc additive manufacturing (WAAM) is usually for fabricating components due to its low equipment cost, high material utilization rate and cladding efficiency. However, its applications are limited by the large heat input decided by process parameters. Here, four 50-layer stainless steel parts with double-pulse and single-pulse metal inert gas (MIG) welding modes were deposited, and the effect of different duty ratios and current modes on morphology, microstructure, and performance was analyzed. The results demonstrate that the low frequency of the double-pulse had the effect of stirring the molten pool; therefore, the double-pulse mode parts presented a bigger width and smaller height, finer microstructure and better properties than the single-pulse mode. Furthermore, increasing the duty ratio from 35% to 65% enlarged the heat input, which then decreased the specimen height, increased the width, and decreased the hardness and the tensile strength.

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