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31.
Dr. Tao Yang Prof. Yan Song Dr. Xiaodong Tian Prof. Huaihe Song Prof. Zhanjun Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(69):16514-16520
Pitch has been used to prepare electrodes by high-temperature heat treatments for supercapacitors, lithium-ion batteries, on account of its rich aromatic ring structure. Here, the toluene-soluble component of pitch is used to prepare a kind of laminated carbon. This was realized by a template-free synthesis at low temperature with the addition of pressure. The toluene-soluble component has a small molecular weight, which makes the thermal deformation ability stronger and then enhances the orientation of the carbon layer with the help of pressure. The prepared anode exhibits a splendid electrochemical performance compared with the traditional graphite anode. A high stable capacity of approximately 550 mAh g−1 at 50 mA g−1, which is much higher than graphite (372 mAh g−1), is obtained. Also, when the current density is up to 2 A g−1, the capacity is about 150 mAh g−1. Surprisingly, it also delivers a superior cycling performance. And when used as the anode/cathode electrode for lithium-ion capacitors, a high energy density can be obtained. The present work offers an opportunity to utilize the pitch source in lithium energy storage with promising cycle life, high energy/power density, and low cost. 相似文献
32.
ABSTRACTNano-polycrystalline diamonds (NPDs) have become fundamental tools for cutting-edge X-ray absorption spectroscopy (XAS) studies at high P/T conditions that opened up new research directions by overcoming previous limitations. Indeed, NPDs yield a continuous and weak X-ray background signal which enables the collection of high-quality XAS data of materials compressed in diamond anvil cells. This is a critical advantage over the classically used single-crystal diamonds that generate strong parasitic signals (glitches) which render the analysis of XAS data in many cases impossible. In this contribution we give an overview of the impact and the scientific opportunities that NPDs opened up for extreme condition XAS spectroscopy at the European Synchrotron Radiation Facility and discuss future needs. 相似文献
33.
针对传统的用于钝头体飞行器的嵌入式大气数据传感系统的经典三点式算法对测压孔配置约束性严格的特点,对经典三点式算法进行了改进及验证。首先,对于经典三点式算法及改进算法进行了论述;其次,针对不同测压孔配置对算法精度的影响进行了系统的评估;最后,对于传统的经典三点式算法与改进三点式算法的优劣进行了比较。结论为:(1)改进的三点式算法对于测压孔的配置敏感性变差,即对测压孔约束很宽松,可用测压孔数增加,从而使得算法的适用性更强;(2)改进的三点式算法的精度与三点式算法相当,但是需要对测压孔进行系统选取及对比验证。 相似文献
34.
Evgeny M. Apfelbaum 《等离子体物理论文集》2019,59(4-5)
The thermophysical properties of low‐temperature Pb plasma are calculated at temperatures 10–100 kK and densities below 0.2 of the solid‐state value. The thermodynamic values (pressure and internal energy) and transport coefficients (electrical conductivity, thermal conductivity, and thermal power) are considered. The plasma composition and thermodynamic parameters are obtained within the chemical approach, namely by means of the solution of the corresponding system of the coupled mass action law equations. Atom ionization up to +4 is taken into consideration. The electronic transport coefficients are calculated within the relaxation time approximation. The results obtained by means of the present model are compared with the available data of other models and experiments. 相似文献
35.
Jiankun Shao Rishav Choudhary David F. Davidson Ronald K. Hanson Samuel Barak Subith Vasu 《Proceedings of the Combustion Institute》2019,37(4):4555-4562
The need for more efficient power cycles has attracted interest in super-critical CO2 (sCO2) cycles. However, the effects of high CO2 dilution on auto-ignition at extremely high pressures has not been studied in depth. As part of the effort to understand oxy-fuel combustion with massive CO2 dilution, we have measured shock tube ignition delay times (IDT) for methane/O2/CO2 mixtures and hydrogen/O2/CO2 mixtures using sidewall pressure and OH* emission near 306?nm. Ignition delay time was measured in two different facilities behind reflected shock waves over a range of temperatures, 1045–1578?K, in different pressures and mixture regimes, i.e., CH4/O2/CO2 mixtures at 27–286 atm and H2/O2/CO2 mixtures at 37–311 atm. The measured data were compared with the predictions of two recent kinetics models. Fair agreement was found between model and experiment over most of the operating conditions studied. For those conditions where kinetic models fail, the current ignition delay time measurements provide useful target data for development and validation of the mechanisms. 相似文献
36.
《中国物理 B》2021,30(9):95207-095207
Extreme ultraviolet(EUV) source produced by laser-induced discharge plasma(LDP) is a potential technical means in inspection and metrology. A pulsed Nd:YAG laser is focused on a tin plate to produce an initial plasma thereby triggering a discharge between high-voltage electrodes in a vacuum system. The process of micro-pinch formation during the current rising is recorded by a time-resolved intensified charge couple device camera. The evolution of electron temperature and density of LDP are obtained by optical emission spectrometry. An extreme ultraviolet spectrometer is built up to investigate the EUV spectrum of Sn LDP at 13.5 nm. The laser and discharge parameters such as laser energy, voltage, gap distance,and anode shape can influence the EUV emission. 相似文献
37.
Conventional biomechanical analyses of human movement have been generally derived from linear mathematics. While these methods can be useful in many situations, they fail to describe the behavior of the human body systems that are predominately nonlinear. For this reason, nonlinear analyses have become more prevalent in recent literature. These analytical techniques are typically investigated using concepts related to variability, stability, complexity, and adaptability. This review aims to investigate the application of nonlinear metrics to assess postural stability. A systematic review was conducted of papers published from 2009 to 2019. Databases searched were PubMed, Google Scholar, Science-Direct and EBSCO. The main inclusion consisted of: Sample entropy, fractal dimension, Lyapunov exponent used as nonlinear measures, and assessment of the variability of the center of pressure during standing using force plate. Following screening, 43 articles out of the initial 1100 were reviewed including 33 articles on sample entropy, 10 articles on fractal dimension, and 4 papers on the Lyapunov exponent. This systematic study shows the reductions in postural regularity related to aging and the disease or injures in the adaptive capabilities of the movement system and how the predictability changes with different task constraints. 相似文献
38.
基于密度泛函理论,采用广义梯度近似法,研究了黄铜矿结构AgAlSe2在高压下的晶体结构、晶格动力学稳定性与电子结构.结果显示:在0 GPa时AgAlSe2的晶格参数与实验值吻合,在13.9 GPa附近,质量密度、Se-Ag键长、Se-Al键长、晶格常数a突然增大,相对晶胞体积V/V0、晶格常数c突然减小,声子谱出现虚频,结构变得不稳定,带隙发生突变,数值呈减小趋势.表明AgAlSe2晶体在13.9 GPa附近发生结构相变.该研究为AgAlSe2晶体在理论上所能承受的高压提供信息支撑. 相似文献
39.
针对传统CFD数值计算方法难以实现风力机动态旋转及其旋转状态下的流固耦合计算,本文结合格子玻尔兹曼(LBM)方法易于处理动态复杂边界的特点及大涡模拟(LES)方法在非稳态涡流结构捕捉上的优势,采用LBM-LES联合方法进行三维风力发电机整机气动性能及尾流结构仿真研究,同时采用尺度自适应方法对尾涡结构进行跟踪和精细化计算。针对NREL PhaseⅥ型试验机进行模拟,得到了与实验结果吻合的流动形态及尾流结构演变规律,分析了尾流区速度演变规律并对比了不同亚格子湍流模型对计算结果的影响. 相似文献
40.