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101.
自动化频谱监测中,信噪分离为宽带频谱序列进一步信号识别和统计提供算法支撑,而现有的频域信噪分离方法存在准确性较低的问题,为提高算法准确性,提出了一种面向宽带频谱的信噪分离方法. 首先,分析实测宽带频谱样本数据特征,采用爱泼斯-普利方法验证了频谱噪声数据样本满足正态性;其次,结合标准差理论,采用邻值比较和窗口划分方法确定信噪分离阈值;最后,以信噪分离准确性为目标,通过迭代优化邻值比较判别值及窗口划分宽度,提高了算法的准确性. 数据验证和对比分析表明,本文方法的信噪分离阈值与频谱噪声吻合较佳,准确性高至90.53%,明显高于现有信噪分离方法,且运行速度快,能够较好地应用于自动化频谱监测的实时信号识别与统计. 相似文献
102.
103.
Qi Wu Huiling Guo Huajun Sun Xiaofang Liu Huiting Sui Fang Wang 《Ceramics International》2021,47(14):19614-19621
Flexible piezoelectric energy harvesters (PEHs) have attracted extensive interest because of their ability to transform mechanical energy into electric power. Here, PEHs were fabricated using P(VDF-TrFE)-based piezoelectric composite films containing lead zirconate titanate (PZT) powder and –OH-functionalized graphene (HOG) nanosheets (HOG-P/P). Among all composites, a high open-circuit voltage (Voc) of approximately 50 Vp-p and a maximum power density of 1.4 μW/cm2 were obtained from a HOG-P/P PEH with 0.10 wt% HOG nanosheets and 15 wt% PZT under bending–releasing mode. Moreover, the PEH exhibited a stable voltage output after 3000 bending–releasing cycles. In addition, the PEH harvested mechanical energy from human body movements and generated an output voltage and current of 60 V and 8 μA during the finger bending–releasing process, lighting up 30 commercial white LEDs. The enhanced piezoelectric performance can be attributed to the introduction of HOG nanosheets and PZT powder. This work provides an effective strategy for improving the output performance of P(VDF-TrFE)-based PEHs. 相似文献
104.
Qi Yafang Chen Yifan Wang Rui Wang Lijing Zhang Fuli Shen Qi Qu Peng Liu Daosheng 《Catalysis Letters》2021,151(6):1546-1555
Catalysis Letters - g-C3N4 has great application prospect in the field of photocatalytic nitrogen fixation owing to the advantages of abundant raw materials, low toxicity, low consumption, high... 相似文献
105.
Xin Li Yurui Wang Minxuan Xu Yueqin Shi Hemiao Wang Xin Yang Haoting Ying Qi Zhang 《应用聚合物科学杂志》2021,138(19):50406
Polymer electrets have revealed great potential application in electromechanical devices because of the low weight, large quasi-piezoelectric sensitivity, and excellent flexibility. For an electret, a permanent and macroscopic electric field exists on the surface, principally led by a macroscopic electrostatic charge on the surface or a net orientation of polar groups inside the object. Here, progress in the development of polymer electrets is reviewed. After a brief retrospect of the research courses and those typical polymer electrets that are classified into fluorine polymer and nonfluorine polymer, we present a survey on the charging methods, including corona, soft X-ray, contact, thermal and monoenergetic particle beams. The latest representative applications (i.e., power harvesting, sensors, field effect transistors, and biomedicine) based on polymer electrets are also summarized. Finally, we complete this review with a discussion on perspectives and challenges in this field. 相似文献
106.
Olusola Bamisile Mustapha Mukhtar Nasser Yimen Qi Huang Olamide Olotu Victor Adebayo Mustafa Dagabsi 《International Journal of Hydrogen Energy》2021,46(52):26272-26288
CO2 based power and refrigeration cycles have been developed and analyzed in different existing studies. However, the development of a CO2 based comprehensive energy system and its performance analysis have not been considered. In this study, the integration of a CO2 based solar parabolic trough collector system, a supercritical CO2 power cycle, a transcritical CO2 power cycle, and a CO2 based cascade refrigeration system for hydrogen production and multigeneration purpose is analyzed thermodynamically. This study aims to analyze and compare the difference in the thermodynamic performance of comprehensive energy systems when CO2 is used as the working fluid in all the cycles with a system that uses other working fluids. Therefore, two comprehensive energy systems with the same number of subsystems are designed to justify the comparison. The second comprehensive energy system uses liquid potassium instead of CO2 as a working fluid in the solar parabolic trough collector and a steam cycle is used to replace the transcritical CO2 power cycle. Results of the energy and exergy performance analysis of two comprehensive energy systems showed that the two systems can be used for the multigeneration purpose. However, the use of a steam cycle and potassium-based solar parabolic trough collector increases the comprehensive energy systems’ overall energy and exergy efficiency by 41.9% and 26.7% respectively. Also, the use of liquid potassium as working fluid in the parabolic trough collectors increases the absorbed solar energy input by 419 kW and 2100 kW thereby resulting in a 23% and 90.7% increase in energetic and exergetic efficiency respectively. The carbon emission reduction potential of the two comprehensive energy systems modelled in this study is also analyzed. 相似文献
107.
Hongwei Shang Yaqin Li Yanghuan Zhang Dongliang Zhao Yan Qi Xiaoyi Xu 《International Journal of Hydrogen Energy》2021,46(34):17840-17852
In order to improve the hydrogen storage performances of TiFe-based alloys, a new type of TiFe0.8-mNi0.2Com (m = 0, 0.03, 0.05 and 0.1) alloys were prepared through vacuum medium-frequency induction melting. XPS results showed that the composition of surface oxide film contains TiO2, FeO and NiO for the cobalt-free alloy, and it also includes CoO and Co3O4 besides the above oxides for the cobalt-containing alloys. The activation temperature is 523, 403, 383 and 373 K for the TiFe0.8-mNi0.2Com (m = 0, 0.03, 0.05 and 0.1) alloys, respectively. The changes of the composition and microstructure of the surface oxide film are the root causes of the reduction of the activation temperature. XRD and SEM analyses showed that all the alloys are composed of the majority phase of TiFe phase and non-hydrogenated phase of Ti2Fe phase. Adding appropriate amount of cobalt is beneficial to inhibiting the generation of Ti2Fe phase and increasing the cell volume of TiFe phase. The hydrogenation capacity is proportional to the content of TiFe phase, which is 1.11, 1.48, 1.54 and 1.29 wt% for the TiFe0.8-mNi0.2Com (m = 0, 0.03, 0.05 and 0.1) alloys at 313 K, respectively. The hydrogenation plateau performance also is improved correspondingly. 相似文献
108.
Qi Zhang Shihui Jiao Boran Wang Zisheng Wang Xinyan Lv Wenwen Wang Yumei Tan Canyu Cui Yan Chen 《International Journal of Hydrogen Energy》2021,46(52):26329-26339
Electrocatalytic water splitting for hydrogen production plays a vital role in the development of new energy field, but there is still a lack of low-content precious metal or cost-effective non-noble metal catalysts for the hydrogen evolution reaction (HER). Therefore, how to develop the catalysts with a smaller amount of precious metal to achieve higher performance is still a major challenge. Herein, we have fabricated Ru–Ni2P@Ni(OH)2/NF-2 heterostructure by phosphating Ni(OH)2/NF and then anchoring Ru on the surface through wet chemical strategy. Benefiting from its optimal ΔGH1 and synergistic effect, this Ru–Ni2P@Ni(OH)2/NF-2 catalyst shows superior electrocatalytic HER kinetics in alkaline electrolyte. A small overpotential of 31 mV is needed for this electrocatalyst to obtain the current densities of 10 mA cm?2 with remarkable durability over 24 h. This work provides a new strategy for the preparation of effective HER electrocatalyst with a low precious metal content. 相似文献
109.
Yulong Zhang Yunfan Gao Zhen Li Zimeng Zheng Xinglian Xu Peng Wang Bin Zheng Zexin Qi 《International Journal of Food Science & Technology》2021,56(11):5518-5532
Wooden breast myopathy affects the quality of fresh and processed chicken breast muscle. The objective of this study was to construct a classification method by instrumental stress, and the effects of wooden breast myopathy on meat quality and oral processing property, and was to explore correlations between stress and oral processing parameters. The severity of wooden breast myopathy was highly correlated to fillet weight (R2 = 0.740), thickness (R2 = 0.826) and hardness (R2 = 0.803) (P < 0.01). The 3D scatter model based on stress is robust and reliable to classify the fillets into four categories (normal, mild, moderate and severe wooden breast fillets), avoiding manual grading. Moisture, fat, collagen, pH, drip loss, cooking loss, thawing loss, purge loss, hardness, gumminess and chewiness significantly increased with the severity of wooden breast myopathy, whereas fat, ash and water/salt-soluble protein contents significantly decreased (P < 0.05). Shear force reached the maximum (36.32 N) when this myopathy was moderate. The myopathy led to an increase in masseter activity and the particle size of the bolus. Significantly higher correlations between stress, Dx(50) (R2 = 0.790), Dx(90) (R2 = 0.771) and D[4,3] (R2 = 0.797) were found (P < 0.01). This study also showed that jaw movement and muscle activity could be used to understand the links between physical property and orally sensory property. 相似文献
110.
耿琦 《机械制造与自动化》2021,50(2):197-199
以某款A0级纯电动汽车研发为例,介绍高压关键零部件在整车上的布置方案和在布置过程中应当注意的问题,包括动力电池、动力总成、高压配电盒、电机控制器、车载充电机布置方案、电动空调压缩机以及其他关键零部件的合理布置方案,为后期车型开发提供参考. 相似文献