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41.
This paper aims to find a reliable, collision-free path in a dynamic environment for highly maneuverable unmanned combat air vehicles (UCAVs). Given the real-time nature of the operational scenario, quick and adaptable reactions of UCAVs are necessary for updates in situational awareness. Therefore, we propose a three dimensional (3D) path planning approach based on the situational space to provide the tactical requirements of UCAVs for tracking targets and avoiding collisions. First, to ensure reliable nonlinear measurements, the interacting multiple model (IMM) algorithm based on a cubature Kalman filter (CKF) is chosen for the tracking and prediction algorithm. A constraint reference frame combining the kinematic model of constant acceleration (CA) is developed to solve the problem of arrival point generation. Second, by analyzing the relative motion between the UCAV and the moving objects, we define the situation space and give the corresponding calculation method. In tracking the moving target, the guidance vector contains the fusion information of displacement and velocity. At the same time, taking advantage of the one-step situation space as the judgment of the threat, we further plan the collision avoidance strategy. Third, as the safety in a practically reachable trajectory of the UCAV possesses the absolute priority, the collision avoidance acceleration accounts for this dominant factor in path planning. Simulations and experimental results prove that the proposed approach can plan a smooth and flyable path in 0.008 s under the premise of soft-landing target tracking. 相似文献
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为了获得一种稳定可控的能源,提出一种栅控石墨烯热电器件。通过对石墨烯通道的载流子输运机理的分析,获得了温度和栅压对通道电阻的影响。依据半经典Mott公式推导了石墨烯塞贝克系数的表达式,同时给出了石墨烯的电导率和热导率模型。最后通过有限元分析(FEA)建模获得不同栅压条件下的器件温度,当栅极电压VB=0 V时,石墨烯热电器件热端和冷端温度差为30 K;当VB=6 V时,最大温差达到50 K;当VB=30 V时,最小温差只有10 K。结果表明,栅压对热电器件的性能有明显的调控性。该研究可为石墨烯热电器件的设计提供理论参考。 相似文献
44.
The inlet/outlet is an important part of a water conveyance system in a pumped storage power station (PSPS). Its hydraulic characteristics are directly related to the operation and economic benefit of the PSPS. Frequent changes between inflow and outflow operations pose significant challenges in the design of the inlet/outlet diffusion segment shape. In this study, an effective optimization method, including three-dimensional parametric modelling, computational fluid dynamics and a genetic algorithm, is introduced and coupled to the design of the diffusion segment shape. The hydraulic characteristics of bi-directional flow, including the head loss, velocity uneven distribution and uneven discharge distribution, are selected as the objective function in the optimization method. Using this method, the recommended shape of the inlet/outlet is studied and its hydraulic characteristics are discussed. The results indicate that the optimized inlet/outlet has better performance. 相似文献
45.
应用M-MIVM预测含钛渣系组元活度 总被引:1,自引:0,他引:1
在钢铁冶炼过程中,随着护炉钛材料和含钛铁矿石的应用,大量的含钛炉渣被生产出来。由于缺少多元含钛渣系的热力学数据,限制了钛资源综合利用技术的深入发展。因此,应用改进的分子相互作用体积模型(M-MIVM(FII)),预测了基础渣系Al2O3-CaO-SiO2、FeO-MnO-SiO2和含钛渣系FeO-MnO-TiO2、FeO-SiO2-TiO2、MnO-SiO2-TiO2、Al2O3-CaO-FeO-TiO2中各组元活度,并与试验值比较。结果表明,M-MIVM(FII)的预测值与试验值符合较好,6个体系总的平均相对误差为11%,该精度处于Turkdogan提出的30%以内的试验误差范围; M-MIVM(FII)在参数拟合与活度预测能力方面均优于MIVM,该模型对多元含钛熔渣体系组元活度具有更好的预测效果。在此基础上,应用M-MIVM(FII)预测Al2O3-CaO-SiO2-TiO2熔体中TiO2活度,并分析其影响因素。结果表明,TiO2活度预测值与试验值吻合良好,且随炉渣碱度、Al2O3含量的增加而降低,该规律与试验规律相一致。M-MIVM(FII)仅通过拟合子二元系活度或者直接由无限稀活度系数就能够预测多元熔体的热力学性质。 相似文献
46.
A method of garment factory workers’ performance monitoring using control chart based on RFID system
Gu Cong Zhou Ruifang Hu Luoyan Gao Guifen 《The International Journal of Advanced Manufacturing Technology》2020,107(3):1049-1059
The International Journal of Advanced Manufacturing Technology - Massive production data of front-line workers are recorded every day by RFID system in garment factory, which are mainly in multiple... 相似文献
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正Power electronic transformer(PET)which is also called solid-state transformer(SST)or smart transformer is a new electric power conversion equipment that can fulfill the function of voltage transformation,galvanic isolation,power flow control and regulation,renewable energy interfacing and so 相似文献
49.
Jianwei Fu Shaomin Wang Xuzhe Wang Ya Yan Kai Wang Meng Gao Qun Xu 《Journal of Porous Materials》2018,25(4):1081-1089
Heteroatom-containing porous carbon nanospheres with a high surface area were firstly fabricated by pyrolysis of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanospheres which were fabricated by a facile polycondensation between hexachlorocyclotriphosphazene and 4,4′-sulfonydiphenol. Then the porous carbon nanosphere-supported Pt nanoparticles (Pt NPs@C-PZS) were synthesized by a simple microwave reduction method, during which Pt NPs were highly dispersed on the surface of carbon supports. The surface morphologies and chemical composition of the as-obtained C-PZS and Pt NPs@C-PZS nanocomposites were characterized by SEM, TEM, XRD, XPS, and Raman spectroscopy. Characterization results showed that the Pt NPs with an average diameter of 2 nm was well anchored onto the surface of C-PZS nanospheres. In addition, the as-prepared Pt NPs@C-PZS nanocomposites exhibited an excellent catalytic capability towards the reduction of 4-nitrophenol to 4-aminophenol by excessive sodium borohydride (NaBH4) at room temperature. 相似文献
50.
Xiao Wang Xiufeng Hao Dan Chang Chongyi Zhu Lili Chen Alideertu Dong Ge Gao 《应用聚合物科学杂志》2019,136(17):47419
N-halamine-based antibacterial agents have high efficiency and rechargeable antibacterial properties. However, their applications are limited due to their complex synthetic process and fuzzy antibacterial mechanism. In this study, a novel N-halamine antibacterial polymer was synthesized by inverse emulsion polymerization and characterized by Fourier transform infrared, nuclear magnetic resonance, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Due to the difficulty of purification, most of the subjects studied previously were hydrophobic polymers, while little research on hydrophilic polymers. In this experiment, this difficulty was overcome by controlling the dosage of sodium hypochlorite and methods of dialysis. Because of the complex cell structure of Gram-negative bacteria, it is difficult for N-halamines to release the oxidizing chlorine into the cell. However, the hydrophilic N-halamines can solve this problem, which showed a stronger antibacterial effect on Gram-negative Escherichia coli synthesized in this study. In addition, the particle size and hydrophilic property of the polymer were changed by changing the amount of initiator, and the differences in their antibacterial properties were studied. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47419. 相似文献