共查询到20条相似文献，搜索用时 490 毫秒
1.
用通用有限元软件分析了夹心式超声换能器的纵向和径向耦合振动特性与其尺寸的关系,在此基础上,提出了有耦合振动时换能器的设计原则,并利用“等效声速”法给出了耦合振动换能器的设计方法。最后对理论结果进行了实验验证。 相似文献
2.
阿司匹林-β-环糊精包合物的制备工艺优选 总被引：1，自引：0，他引：1
目的寻找阿司匹林-β-环糊精包合物（ASP-β-CYD）的最佳制备工艺。方法以包合率、包合物收率为指标,采用正交实验法,初步研究饱和水溶液搅拌法、超声波法和研磨法包合阿司匹林的最佳工艺。结果饱和水溶液法制备包合物的最佳工艺为阿司匹林的质量与β-环糊精的质量的比为1：8、包合温度为50℃、包合时间为2h、干燥温度50℃。包合率可以达到79.61%,包合物收率为76.19%。超声波法的最佳包合条件为阿司匹林的质量与β-环糊精的质量的比为1：8、超声时间为40min、干燥温度为50℃。包合率可以达到73.18%,包合物收率为79.26%。研磨法的最佳包合条件为阿司匹林的质量与β-环糊精的质量的比为1：8、研磨时间为20min、干燥温度为60℃。包合率可以达到84.41%,包合物收率为74.35%。结论超声波法制备包合物得到的包合率、综合评价均比其他两种方法高。 相似文献
3.
This paper presents and verifies a new idea for constructing an ultrasonic motor (USM). The stator contains several vibrators fabricated by bonding piezoelectric ceramics (PZTs) to a metal base. When two alternating current (AC) voltages with a 90° phase difference are applied to the PZTs, longitudinal and bending modes are excited in the vibrator. The bending vibrations of the vibrators are stacked to form the torsional vibration of the stator, ultimately generating longitudinal-torsional composite vibration. Both vibrators and the stator are excited to the resonance state. A standing wave is formed by superposition of longitudinal and torsional modes. The proposed motor is an in-plane vibration motor because the vibrations of the stator are in the circumferential plane. The finite element method (FEM) is used to validate the feasibility of the proposed motor. The fabricated stator contains five vibrators. The tested resonance frequencies of longitudinal and torsional modes are 44.42 kHz and 43.83 kHz, respectively. The stall torque is 0.3 N·m and no-load speed is 45 r/min. The highest efficiency is 30%. The applied driving voltage is 100 Vo-p (peak voltage) at 43.9 kHz. The designed motor is a parallel-actuated integral motor. It allows the vibrators to operate synchronously, and overcomes asynchronous issues that occur in traditional multi-vibrator motors. 相似文献
4.
种子是生命力的载体 ,其传热传质的研究已经从宏观迈向微观 ,从整体迈向细胞、原生质、细胞器、分子膜的水平 .用透射电镜对未干与干燥的白菜种子进行了子叶切片观察 ,发现干燥后的种子子叶细胞仅在细胞壁有皱褶 ,细胞器无明显变化 .种子发芽过程中酶活性检测表明 ,与未干种子相比 ,萌发 48h,经 45℃干燥 2 h的种子α-酶的相对活性下降了 5 .8% ;经 67℃干燥 2 h的种子α-酶的相对活性下降了 3 0 .1% .可见 ,干燥参数影响种子的微观结构与酶的活性 ,与种子干燥的临界安全温度相同 ,酶的活性是干燥温度、初含水率与加热时间的函数 相似文献
5.
采用正交试验法优化都匀楼梯草中总黄酮的超声波提取工艺,考察超声波作用时间、乙醇浓度和液料比3个因素对都匀楼梯草总黄酮提取率的影响,确定都匀楼梯草总黄酮的优化超声波提取工艺条件为：提取溶剂80％乙醇,料液比1∶25,超声波作用时间40 min,最佳提取率为1.62％.乙醇提取物抑制DPPH自由基的能力IC50=125.25μg/mL,说明都匀楼梯草不同极性部位均具有一定的抗氧化活性. 相似文献
6.
为确定香菜总黄酮的超声最佳提取工艺条件,采用正交试验法,考察溶剂浓度、超声时间、超声温度、料液比对提取率的影响。所考察的因素对香菜总黄酮的提取率影响顺序由大到小为：超声时间,超声温度,乙醇浓度,物料比。超声提取的最佳条件为：超声时间30 min,超声温度30℃,乙醇浓度80%,物料比1∶35超声波法提取效率高于常规的提取方法,并具有提取时间短、简单、无需加热等优点。 相似文献
7.
酱油渣中提取油脂和黄酮 总被引：1，自引：0，他引：1
[目的]探讨从酱油渣中提取油脂和黄酮类物质的最佳工艺参数,为酱油渣资源的进一步开发利用提供基础数据.[方法]在单因素实验的基础上,采用正交设计方法,研究各因素对油脂和黄酮提取率的影响.[结果]研究表明,油脂提取最佳条件为:酱油渣与异丙醇比例为1:13,超声温度50℃,超声时间30 min,该条件下油脂的提取率为34.76%;从脱脂酱油渣中提取黄酮的最佳条件为:50%乙醇、料液比1:30、超声时间15 min、提取温度60℃,在此条件下,黄酮的提取量为2.471 0 mg/g.[结论]利用超声波辅助提取技术从酱油渣中提取油脂和黄酮可行. 相似文献
8.
张志良 《上海大学学报(英文版)》2007,11(2):193-194
An overview of the research conducted in the area of linear and nonlinear vibrations of loudspeakers and revolution shells was given in the turning-point frequency range in Chapter 1. It shows that some problems concerning vibrations of shells in the turning-point range have to be further studied. 相似文献
9.
运用响应曲面优化法优化超声波辅助的茶粕中提取茶皂素工艺,建立以75％乙醇为提取剂的料液pH值、浸提温度、浸提时间、液固比和超声波功率等因素与茶皂素提取率间数学模型,据此确定最佳工艺条件为料液pH值8．0、浸提温度40℃、浸提时间4h、液固比8：1和超声波功率80W,此时实际茶皂素提取率8．041％（n=5）,与模型预测接近。 相似文献
10.
Improving the Fatigue Performance of the Welded Joints of Ultra-Fine Grain Steel by Ultrasonic Peening 总被引：2，自引：0，他引：2
Contrast tests were carried out to study the fatigue performance of the butt joints treated by ultrasonic peening, aiming at the improvement of ultrasonic peening treatment(UPT) on welded joints of a new material. The material is a new generation of fine grain and high purity SS400 steel that has the same ingredients as the traditional low carbon steel. The specimens are in two different states:welded and ultrasonic peening conditions. The corresponding fatigue testing data were analyzed according to the regulation of the statistical method for fatigue life of the welded joints established by International Institute of Welding(IIW). Welding residual stress was considered in two different ways: the constant stress ratio R = 0.5 and the Ohta method. The nominalstress-number (σ-N) curves were corrected because of the different plate thickness compared to the standard and because there was no mismatch or angular deformation. The results indicated that: 1 ) Compared with the welded specimens, when the stress range was 200 MPa, the fatigue life of the SS400 steel specimens treated by ultrasonic peening is prolonged by over 58 times, and the fatigue strength FAT corresponding to 106 cycles is increased by about 66％; 2) As for the SS400 butt joint ( single side welding double sides molding) , after being treated by UPT, the nominal S-N curve (m = 10) of FAT 100 MPa(R =0.5) should be used for fatigue design. The standard S-N curves of FAT 100 MPa (R = 0.5, m = 10) could be used for fatigue design of the SS400 steel butt joints treated by ultrasonic peening. 相似文献
11.
Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the
characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency
vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced
shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were
performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex,
and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors
of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency
vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The
experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting
countermeasures. 相似文献
12.
任百祥 《河北职业技术学院学报》2014,(2):55-58
采用纳米TiO2为催化剂,超声辐照为主要手段对实际印染工业废水进行了降解实验研究,考察了各种反应参数对印染废水降解效果的影响。结果表明,纳米TiO2对印染工业废水的超声降解效果具有明显的辅助和提高。当超声波频率为45kHz,功率为200W,溶液初始pH值为2.63,超声反应时间为150min的条件下,印染工业废水的COD去除率为73%,而同样条件下,投加750mg/L纳米TiO2,其超声降解废水COD去除率可达90.2%。 相似文献
13.
对新拌混凝土采用了3个不同时刻作为振动的起振点,分别按照3种不同频率和振幅组合进行实验,将受振动的试件和基准（未振动）试件在标准养护室养护到一定龄期后进行抗压试验,从而判断受振动混凝土1d、3d及28d抗压强度变化趋势。测量了不同龄期的72组抗压强度,通过对实验数据进行统计分析,其中有17组强度是降低的,降低的数据在6%以内的占了16组。试验结果表明：对处于初、终凝前后混凝土材料施加试验中设计的振动,对混凝土的抗压强度有一定影响。 相似文献
14.
Wen-yi Deng Xiao-dong Li Jian-hua Yan Fei Wang Sheng-yong Lu Yong Chi Ke-fa Cen 《浙江大学学报(A卷英文版)》2009,10(11):1670-1677
The emission and contact drying kinetics of the paper mill sludge （PMS） were studied through experiments carried out in a paddle dryer. To get a better understanding of its drying mechanism, a penetration model developed by Tsotsas and Schlünder （1986） was used to simulate the drying kinetics of the PMS. The result indicated that this kinetics could be divided into three phases： pasty, lumpy and granular phases, and could be successfully simulated by the penetration model as the related sludge parameters were integrated into the model. The emission rate curves of the volatile compounds （VCs） were interrelated to the drying rate curve of the PMS, especially for volatile fatty acids （VFAs） and ammonia in this study. 相似文献
15.
High-temperature coal tar was extracted with petroleum ether(PE) under ultrasonic irradiation and the extracts were analyzed with gas chromatograph/mass spectrometer.The acearylene fractions including acenaphthylene,aceanthrylene and cyclopentapyrene were enriched together and named E,which was then transferred to a cartridge in Isolera-One flash chromatography.Three groups of compounds were eluted out with ethyl acetate/PE mixed solvent(volume ratio 1:9) and named E 1,E 2 and E 3 according to their main components.Acenaphthylene accounted for 78.2% in E 1,aceanthrylene 71.6% in E 2 and cyclopentapyrene 75.9% in E 3,respectively.The three groups of acearylenes were purified by Sephadex LH-20 column chromatography with ethanol/cyclohexane mixed solvent(volume ratio 1:4),and then confirmed with nuclear magnetic resonance spectrometer.This method indicates that flash chromatography has a good effect on separating the compounds with a similar structure after extraction under ultrasonic irradiation. 相似文献
16.
INTRODUCTION Advanced oxidation processes (AOPs), inwhich high reactive and non-selective hydroxylradicals in aqueous solution are generated, havearoused among scientists great interest in destroyingtoxic and biorefractory organics of wastewater. AOPssuch as photocatalyzation, electrocatalyzation, ozo-nolyzation, and wet air oxidation have been intensiv-els studied. There is a trend in recent years to developprocesses combining two or more AOPs such asO3/UV, O3/H2O2, O3/H2O2/… 相似文献
17.
18.
目的分析上消化道出血胃B超图象特征,探讨B超对上消化道出血及其病因诊断的意义.方法;选择上消化道出血活动期的位院患者49例,分别于空腹及饮水后依次探查贲门、胃体、胃窦、十二指肠及其邻近器官,记录图像,并结合内镜病理及X线结果进行分析.结果49例中.B超检出相关疾病41例,命中37例;检出率及准确率分别为83.7%和75.5%,X线报告32例,命中29例,检出率及准确率分别为65.3%和59.2%,统计分析结果显示该两种检查方法有显著差异(P＜0.05).结论B型超声可作为上消化道出血病因诊断较可靠的方法. 相似文献
19.
采用正交试验L9（3^4）,对加热回流提取和超声提取优化广东紫珠总黄酮的提取工艺进行了比较研究.以提取物中总黄酮得率为评价指标,利用紫外分光光度法测定黄酮的含量.结果表明,加热回流提取的最佳工艺条件为A1 B3 C2,即乙醇浓度为60％、水浴温度为80℃、提取时间为2 h;超声法为A2 B1 C2,即乙醇浓度为70％、固液比为1：20、超声40 min.芦丁对照品9.4～75.2μg·mL^1范围内与吸光度呈良好的线性关系.加热回流提取法优于超声法,黄酮提取率达到9.27％. 相似文献
20.
超声波法提取灵香草浸膏工艺研究 总被引：1，自引：0，他引：1
设计以超声波法对灵香草浸膏进行提取的试验,研究提取频率、提取温度、乙醇浓度、提取次数、提取时间等对浸膏得率的影响,确定提取灵香草浸膏的最佳条件后,对所得粗产品进行脱色试验,优化出租浸膏脱色的最佳条件。研究结果表明：超声波法提取灵香草浸膏的最佳条件是在80％乙醇中以提取频率65kHz进行超声波提取3次,提取时间为1．5h,温度为85℃,灵香草碎段为2--4cm;浸膏脱色的最佳条件是加95％工业乙醇沉淀至乙醇质量分数浓度85％后,用与原料质量比例为25％的活性碳脱色。在此最佳工艺条件下,灵香草浸膏的得率为20．5％。 相似文献