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排序方式: 共有8503条查询结果,搜索用时 15 毫秒
1.
Xu Cheng Rong Jiawei Chen Yulin Wu Hang Duan Shihong 《International Journal of Wireless Information Networks》2022,29(1):1-13
International Journal of Wireless Information Networks - Source seeking problem has been faced in many fields, especially in search and rescue applications. We proposed a virtual structure-based... 相似文献
2.
Quan Nguyen Minh Quoc Dat Lai Hoang Nguy Minh Minh Tu Tran Kieu Ngoc Lam Gia Uyen Le My Phung Hang Hoang Dung Nguyen Tran Diem Ai Chau Ngoc Thuc Trinh Doan 《International Journal of Food Science & Technology》2022,57(7):4507-4517
To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices. 相似文献
3.
Rui-Qi Yao Yi-Tong Zhou Hang Shi Wu-Bin Wan Qing-Hua Zhang Lin Gu Yong-Fu Zhu Zi Wen Xing-You Lang Qing Jiang 《Advanced functional materials》2021,31(10):2009613
Electrocatalytic hydrogen evolution in alkaline and neutral media offers the possibility of adopting platinum-free electrocatalysts for large-scale electrochemical production of pure hydrogen fuel, but most state-of-the-art electrocatalytic materials based on nonprecious transition metals operate at high overpotentials. Here, a monolithic nanoporous multielemental CuAlNiMoFe electrode with electroactive high-entropy CuNiMoFe surface is reported to hold great promise as cost-effective electrocatalyst for hydrogen evolution reaction (HER) in alkaline and neutral media. By virtue of a surface high-entropy alloy composed of dissimilar Cu, Ni, Mo, and Fe metals offering bifunctional electrocatalytic sites with enhanced kinetics for water dissociation and adsorption/desorption of reactive hydrogen intermediates, and hierarchical nanoporous Cu scaffold facilitating electron transfer/mass transport, the nanoporous CuAlNiMoFe electrode exhibits superior nonacidic HER electrocatalysis. It only takes overpotentials as low as ≈240 and ≈183 mV to reach current densities of ≈1840 and ≈100 mA cm−2 in 1 m KOH and pH 7 buffer electrolytes, respectively; ≈46- and ≈14-fold higher than those of ternary CuAlNi electrode with bimetallic Cu–Ni surface alloy. The outstanding electrocatalytic properties make nonprecious multielemental alloys attractive candidates as high-performance nonacidic HER electrocatalytic electrodes in water electrolysis. 相似文献
4.
基于微电子机械系统(MEMS)工艺,提出一种多层圆片堆叠的THz硅微波导结构及其制作方法。为了验证该结构在制作THz无源器件中的优势,基于6层圆片堆叠的硅微波导结构,设计了一种中心频率365 GHz、带宽80 GHz的功率分配/合成结构,并对其进行了仿真。研究了制作该结构的工艺流程,攻克了工艺过程中的关键技术,包括硅深槽刻蚀技术和多层热压键合技术,并给出了工艺结果。最终实现了多层圆片堆叠功率分配/合成结构的工艺制作和测试。测试结果表明,尽管样品的插入损耗较仿真值增加3 dB左右,考虑到加工误差和夹具损耗等情况,样品主要技术指标与设计值较为一致。 相似文献
5.
Nano Research - Doping control has been a key challenge for electronic applications of van der Waals materials. Here, we demonstrate complementary doping of black phosphorus using controlled ionic... 相似文献
6.
为保障8809工作面推进过空巷区域的安全生产,通过对过空巷区域时覆岩变形规律的分析,得出工作面与未支护的空巷间煤柱宽度为14m时,空巷围岩出现失稳。基于分析结果,确定J09-01和J09-02空巷采取锚网索+工字钢梁的支护技术,J09-03和J09-04空巷采用预充填技术,工作面顺利通过补强支护和充填空巷区域。 相似文献
7.
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
8.
9.
Meng Zhang Xuezhang Xiao Zhouming Hang Man Chen Xuancheng Wang Nan Zhang Lixin Chen 《International Journal of Hydrogen Energy》2021,46(1):814-822
Magnesium hydride, as a potential solid state hydrogen carrier has attracted great attention around the world especially in the energy storage domain due to the high hydrogen storage capacity and the good cycling stability. But kinetic and thermodynamic barriers also impede the practical application and development of MgH2. Nanoscale catalysts are deemed to be the most effective measure to overcome the kinetic barrier and lower the temperature required for hydrogen release in MgH2. NbN nanoparticles (~20 nm) with intrinsic Nb3+-N and Nb5+-N were prepared using the molten salt method and used as catalysts in the MgH2 system. It is found that the NbN nanoparticles exhibit a superior catalytic effect on de/rehydrogenation kinetics for the MgH2/Mg system. About 6.0 wt% hydrogen can be liberated for the MgH2+5NbN sample within 5 min at 300 °C, and it takes 12 min to desorb the same amount of hydrogen at 275 °C. Meanwhile, the MgH2+5NbN sample can absorb 6.0 wt% hydrogen within 16 min at 150 °C, and absorb 5.0 wt% hydrogen within 24 min even at 100 °C. Particularly, the catalyzed samples exhibit excellent hydrogen absorption/desorption kinetic stability. After multiple cycles, there is no kinetic attenuation and the hydrogen capacity remains at about 6.0 wt%. It is demonstrated that the NbN nanoparticles with intrinsic multiple valence can be the critical effect in improving the hydrogen storage kinetics of MgH2. The stability of Nb4N3 phase and Nb3+-N and Nb5+-N valence states can ensure a stable catalytic effect in the system. 相似文献
10.
Xuancheng Wang Xuezhang Xiao Jiaguang Zheng Zhouming Hang Wenping Lin Zhendong Yao Meng Zhang Lixin Chen 《International Journal of Hydrogen Energy》2021,46(46):23737-23747
Magnesium borohydride, Mg(BH4)2, is ball-milled with Ti nano-particles. Such catalyzed Mg(BH4)2 releases more hydrogen than pristine Mg(BH4)2 does during isothermal dehydrogenation at 270, 280, and 290 °C. The catalyzed Mg(BH4)2 also exhibits better dehydrogenation kinetics than the pristine Mg(BH4)2. Based on kinetics model fitting, the activation energy (Ea) of the catalyzed Mg(BH4)2 is calculated to be lower than pristine Mg(BH4)2. During partial dehydrogenation, the catalyzed Mg(BH4)2 releases 4.23 wt % (wt%) H2 for the second dehydrogenation at 270 °C, comparing to 4.05, and 3.75 wt% H2 at 280, and 290 °C. The reversibility of 4.23 wt% capacity is also one of the highest for Mg(BH4)2 dehydrogenation under mild conditions such as 270 °C as reported. 4 cycles of Mg(BH4)2 dehydrogenation are conducted at 270 °C. The capacities degrade during 4 cycles and tend to be stable at about 3.0 wt% for the last two cycles. By analyzing the hydrogen de/absorption products of the catalyzed sample, Mg(BH4)2 is found to be regenerated after rehydrogenation according to Fourier Transform Infrared (FTIR) spectroscopy. Ti nano-particles can react with Mg(BH4)2 during ball-milling and de/rehydrogenation. The products include TiH1.924, TiB, and TiB2, which can improve the dehydrogenation properties of Mg(BH4)2 from a multiple aspect. 相似文献