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991.
992.
Chen Li Peng Xiaoping Tian Jing Liu Jiaxiang 《Multidimensional Systems and Signal Processing》2018,29(4):1895-1904
Multidimensional Systems and Signal Processing - Traffic surveillance video is recorded in uncontrolled outdoor scenarios. If the camera view gets obstructed by the leaves, the video will fail to... 相似文献
993.
994.
Formation of Uniform Water Microdroplets on Wrinkled Graphene for Ultrafast Humidity Sensing 下载免费PDF全文
Zhen Zhen Zechen Li Xuanliang Zhao Yujia Zhong Li Zhang Qiao Chen Tingting Yang Hongwei Zhu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(15)
Portable humidity sensors with ultrafast responses fabricated in wearable devices have promising application prospects in disease diagnostics, health status monitoring, and personal healthcare data collecting. However, prolonged exposures to high‐humidity environments usually cause device degradation or failure due to excessive water adsorbed on the sensor surface. In the present work, a graphene film based humidity sensor with a hydrophobic surface and uniformly distributed ring‐like wrinkles is designed and fabricated that exhibits excellent performance in breath sensing. The wrinkled morphology of the graphene sensor is able to effectively prevent the aggregation of water microdroplets and thus maximize the evaporation rate. The as‐fabricated sensor responds to and recovers from humidity in 12.5 ms, the fastest response of humidity sensors reported so far, yet in a very stable manner. The sensor is fabricated into a mask and successfully applied to monitoring sudden changes in respiratory rate and depth, such as breathing disorder or arrest, as well as subtle changes in humidity level caused by talking, cough and skin evaporation. The sensor can potentially enable long‐term daily monitoring of breath and skin evaporation with its ultrafast response and high sensitivity, as well as excellent stability in high‐humidity environments. 相似文献
995.
996.
Hua Zhu Rui Tian Lei Han Liping Wang 《Numerical Heat Transfer, Part B: Fundamentals》2020,78(3):141-159
AbstractNumerical simulations were carried out to study the heat transfer and friction characteristics for Stirling engine heater tubes with three-dimensional internal extended micro-rib. During the numerical simulations, phase angle in a cycle ranged from 0° to 360°. The results represent that the friction factor (f) increased with micro-rib length (L) and micro-rib height (H) for enhanced tube within the range of parameters in this study. For the micro-rib heat tube of L?=?60 mm and H?=?0.9 mm, the j was equal to 1.44 and the average Stanton number St was significantly improved up to 1.287 compared to smooth tube, the friction factor f was also increased by almost 2.32. The outlet pressure from 0.7 Mpa to 1 Mpa with the cosine change is presented as the phase angle increases. Therefore the benefits are apparent for micro-rib heat tube in Stirling engine. 相似文献
997.
针对现有驱动平台在传统PID参数控制下Y方向平动实验中出现的波动情况进行分析,猜测波动的原因是由于平台结构分布不均匀造成的。针对波动情况,建立在环形永磁铁和柱形永磁铁结构分布不均匀情况下驱动平台的数学模型。并对结构不均匀情况下数学模型进行Y方向的仿真分析。仿真结果表明,分布不均匀情况下的数学模型在仿真过程中会出现波动。仿真结果与猜测结果相同。实验过程中的波形情况是由于驱动平台的结构分布不均匀造成的。 相似文献
998.
A hybrid first-principles/Monte Carlo simulation is combined with experiments to study the structure and elastic properties of CoCrNix (x = 1-0.5) alloys. The experimental X-ray diffraction patterns show that the structures have changed from the single-phase face-centered cubic (FCC) structure at x = 1-0.8 to the coexistence of FCC and the hexagonal close-packed structures at x = 0.7-0.5, which is further confirmed by calculations on mixing energies. The elastic moduli by calculation are basically in agreement with experiments. Room-temperature tension shows that the six alloys have a certain plasticity, the strength and plasticity of the alloys have a linear decrease with the decrease in Ni contents, and the plasticity of the alloys drops from 84 to 23%. Furthermore, first-principles density function theory calculations were employed to reveal the electronic and magnetic structures of alloys. The electron density of states for all alloys is asymmetrical, which illustrates that the alloys are ferromagnetism. It is found that Cr atoms can suppress the ferromagnetism of alloys, since Cr atoms have both positive and negative magnetic moments in all alloys. 相似文献
999.
Dr. Zhen Liu Dr. Yang Gao Tian Zeng Prof. Keary M. Engle 《Israel journal of chemistry》2020,60(3-4):219-229
During the past decade, many research groups have described catalytic methods for 1,2-carboboration, allowing access to structurally complex organoboronates from alkenes. Various transition metals, especially copper, palladium, and nickel, have been widely used in these reactions. This review summarizes advances in this field, with a special focus on the catalytic cycles involved in different metal-catalyzed carboboration reactions, as well as the regio- and stereochemical consequences of the underlying mechanisms. 1,2-Carboboration of other unsaturated systems, such as alkynes and allenes, is outside of the scope of this review. 相似文献
1000.
Nadezhda S. Tian Tamara K. Meleshko Galina A. Polotskaya Iosif V. Gofman Anna V. Kashina Nina V. Kukarkina Elena N. Vlasova Zoolsho F. Zoolshoev Alexander V. Yakimansky 《Polymer Engineering and Science》2020,60(3):481-490
Composite films based on polyamide (poly(m-phenylene-iso-phthalamide)) (PA) and a brush-like polymer with polyimide (PI) backbone and side poly(methyl methacrylate) chains (PI-PMMA) were prepared by mixing individual solutions of PA and PI-PMMA and subsequent film casting. Macromolecular brushes with the same backbone length and density of side chains but with various lengths of side PMMA chains were synthesized via activator generated by electron transfer atom transfer radical polymerization. Interactions between PA and PI-PMMA, as well as distribution of PI-PMMA filler inside the PA matrix, were studied by viscometry, dynamic light scattering, differential scanning calorimetry, scanning electron microscopy, and IR spectroscopy. The mechanical properties of polymer samples were also investigated. Microphase separation was revealed in PA/PI-PMMA films. The length of side chains influences interactions between PA and PI-PMMA. At the same time, the degree of reduction in the rigidity parameters and in the elasticity parameter depends on the side chain length. Diffusion membranes were prepared on the basis of compositions with the best mechanical properties; these membranes proved to be highly efficient in pervaporation of methanol–hexane mixture. It was established that the fluxes and separation factors of the studied membranes are several times higher as compared to the corresponding characteristics of known commercial membranes. POLYM. ENG. SCI., 60:481–490, 2020. © 2019 Society of Plastics Engineers 相似文献