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91.
单相旋转型驻波超声电机的数学模型及仿真 总被引：1，自引：0，他引：1
尽管单相驱动的旋转型驻波超声电机的原理样机早巳研制成功，但对这类电机的运动机理的研究却一直局限在定性分析上。本文将从能量角度，根据Hamilton变分原理，定、转子摩擦界面采用纯滑动模型建立了该种电机的数学模型；并根据此模型，用MATLAB语言作了计算机仿真，得到了该种电机的开、关过程动态响应。 相似文献
92.
C/C-SiC复合材料的制备及其湿式摩擦磨损性能研究 总被引：3，自引：0，他引：3
采用T700炭纤维针刺毡,经超声振动渗硅、化学气相沉积(CVD)、硅化处理及液相浸渍/炭化新工艺制备SiC呈\"岛状\"分布的C/C-SiC复合材料,利用偏光显微镜和扫描电子显微镜观察其微观组织结构并分析其形成机制,在MM-1000型湿式摩擦磨损试验机上研究C/C-SiC复合材料的摩擦磨损性能.结果表明:在初始转速恒定的条件下,动摩擦系数随制动比压的增加而逐渐减小;当制动比压恒定时,摩擦系数随初始转速的增加呈现出先增大而后降低的趋势;在本文试验条件下,摩擦系数稳定在0.088～0.126之间;在300次磨损试验后,其磨损量检测值为0. 相似文献
93.
超声马达梯度涂层摩擦材料研究 总被引：1，自引：0，他引：1
超声马达摩擦材料应同时具有良好的摩擦学特性和一定的接触变形要求,目前所用单一均质结构摩擦材料较难满足这一要求,需要研制新型摩擦材料.本文从摩擦学的减摩结构模型反推出一种增摩结构模型,针对超声马达对摩擦材料的要求,提出梯度涂层摩擦材料的设计思想,采用表面黏涂法研制了一种具有梯度结构的涂层摩擦材料.利用超声马达模拟试验装置考察了涂层厚度对超声马达性能的影响,初步验证了模型的正确性.在本文的试验条件下,当涂层材料表层厚度为1mm,底层厚度为0.7mm左右时,超声马达具有较好的性能.与其它种类的摩擦材料相比较,梯度涂层摩擦材料可以满足超声马达的使用要求,可望提升超声马达的性能,具有良好的发展前景. 相似文献
94.
《液相色谱法及相关技术杂志》2012,35(9):730-743
A novel and simple method for the determination of 7 antioxidants: 4,4′-Isopropylidendiphenol(BPA), tert-Butyl-4-hydroxyanisole(BHA),2,6-Di-tert-butyl-4-p-cresol(BHT),2,6-Di-tert-butyl-4-hydroxy-methylphenol(Ionox 100),2,2′-Methylenebis-(6-tert-butyl-4-ethylphenol)(AO425), Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxy- phenyl)propionate (Irganox 1010), and Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Irganox 1076); 8 ultraviolet absorbents: 2,4-Di-hydroxy-benzophenone(UV-0),2-Hydroxy-4-methoxy-benzophenone(UV-9),2-(2′-Hydroxy-5′-methylphenyl)(UV-P),2,2′-Di-hydroxy-4-methoxy-benzophenone(UV-24),2-(2H-Benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol(UV-234),(2′-Hydroxy-3′-tert-5′-methylphenyl)-5-chlorobenzotriazole(UV-326),2-(2′-Hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole(UV-327),2-Hydroxy-4-n-octoxy-Benzophenone(UV-531); and 2 fire retardants: 2,2′,4,4′,6,6′- Hexabromobiphenyl, Decabromodiphenyl oxide in plastic food package using ultrasonic extraction coupled with ultra performance liquid chromatography–photodiode array detector (UPLC-PDA) has been developed. Parameters affecting the efficiency in the process such as extraction solvent, extraction volume, and chromatographic conditions were studied in order to determine operating conditions. The merits of the optimized method were as follows: limits of detection (LODs) of the 17 additives ranged from 0.01 to 0.55 µg mL−1, linear over the range studied (0.05–10 µg mL−1), average spiked recoveries for most of the analytes in samples larger than 70.24%, except UV-327 and Irganox 1076(58.27% and 65.53%, respectively), and RSDs smaller than 16.11%. A methodology has been proposed for the analysis of the 17 additives in plastic food package. 相似文献
95.
96.
Electrolysis of water in acidic media generally requires noble metals (oxides) to enhance the catalyst activity and durability in the oxygen evolution reaction (OER). Bimetallic Ir−Fe supported on reduced graphene oxide (IFG) is prepared by ultrasonic spray pyrolysis, followed by acid and/or heat treatment. Physical and electrochemical methods are used to elucidate the effect of the physical and chemical properties of the IFG catalysts modified by spray pyrolysis and post treatment on the OER activity and stability under harshly oxidizing conditions in 0.1 M HClO4. The IFG-AHT catalyst synthesized via ultrasonic pyrolysis followed by acid and heat treatment exhibits superior OER activity among the IFG catalysts. The mass activity was two-fold higher and the stability is superior to that of the commercially available Ir catalyst, indicating that the metal (oxide) dissolution rate and the interaction between Ir and the hybrid support affect the cost and lifetime of OER catalysts. 相似文献
97.
A new method for multi-component synthesis of 1,4-dihydropyridine derivatives (1,4-DHPs) in the presence of meglumine supported on multiwalled carbon nanotubes (MWCNTs@meglumine) as a new heterogeneous, highly efficient and reusable catalyst was investigated. The reaction was performed under ultrasonic irradiation in EtOH at room temperature. A new, highly efficient heterogeneous catalyst, short reaction times, high to excellent yield of products, and safe and clean conditions are the advantages of the presented method. 相似文献
98.
《Journal of separation science》2017,40(3):697-701
An effective method for the simultaneous determination of docosahexaenoic acid and eicosapentaenoic acid in common seafood by gas chromatography was developed and validated. Total docosahexaenoic acid and eicosapentaenoic acid were extracted from seafood by ultrasonic cell crusher assisted extraction and methyl esterified for gas chromatography analysis in the presence of the internal standard. The linearity was good (r > 0.999) in 9.59 ∼ 479.5 μg/mL for docosahexaenoic acid and 9.56 ∼ 477.8 μg/mL for eicosapentaenoic acid. The intrarun and interrun precisions were both within 4.8 and 6.1% for the two analytes, while the accuracy was less than 5.8%. The developed method was applied for determination of docosahexaenoic acid and eicosapentaenoic acid in six kinds of seafood. The result showed the content of docosahexaenoic acid and eicosapentaenoic acid was all higher than 1 mg/g in yellow croaker, hairtail, venerupis philippinarum, mussel, and oyster. Our work may be helpful for dietary optimization and production of docosahexaenoic acid and eicosapentaenoic acid. 相似文献
99.
With the reduction of crude oil throughout the world, enhance oil recovery technology has become a major oil research topics, which can greatly increase the recovery ratio of the crude oil before the dawning of renewable energy era. Near-well ultrasonic processing technology, as one new method, has attracted more attention for Enhanced Oil Recovery due to its low cost, good applicability and no environmental pollution in recent rears. There are two important relevant aspects about Near-well ultrasonic processing technology: (a) how to enhance the oil flow through the rocks into the pumping pool and (b) how to reduce the oil viscosity so that it can be easier to pump. Therefore, how to design a high-power ultrasonic equipment with excellent performance is crucial for Near-well ultrasonic processing technology. In this paper, recent new high-power ultrasonic transducers for Near-well ultrasonic processing technology are summarized. Each field application of them are also given. The purpose of this paper is to provide reference for the further development of Near-well ultrasonic processing technology.With the reduction of crude oil throughout the world, enhance oil recovery technology has become a major oil research topics, which can greatly increase the recovery ratio of the crude oil before the dawning of renewable energy era. Near-well ultrasonic processing technology, as one new method, has attracted more attention for Enhanced Oil Recovery due to its low cost, good applicability and no environmental pollution in recent rears. There are two important relevant aspects about Near-well ultrasonic processing technology: (a) how to enhance the oil flow through the rocks into the pumping pool and (b) how to reduce the oil viscosity so that it can be easier to pump. Therefore, how to design a high-power ultrasonic equipment with excellent performance is crucial for Near-well ultrasonic processing technology. In this paper, recent new high-power ultrasonic transducers for Near-well ultrasonic processing technology are summarized. Each field application of them are also given. The purpose of this paper is to provide reference for the further development of Near-well ultrasonic processing technology 相似文献
100.
Zinc sulfide (ZnS) thin films have been deposited on Si (1 0 0) substrate using ultrasonic spray pyrolysis. X-ray diffraction (XRD) analysis revealed that the films are (0 0 2) preferentially oriented with c-axis-oriented wurtzite structure. The crystallinity has been found to improve with film thickness in the 180–6000 nm range. Film structure has been analyzed by XRD, scanning electron microscope, FTIR, and Raman spectroscopies, while the stoichiometry has been verified by energy-dispersive spectroscopy and particle-induced X-ray emission techniques. Electrical properties of the grown films were characterized by current–voltage and capacitance–voltage measurements where, the films show better conducting behavior at higher thickness. 相似文献