超声导波检测管道缺陷的实验研究

介绍了超声导波在管道缺陷检测中的应用,并介绍了超声导波的检测原理。利用超声导波对管道缺陷进行检测,通过实验对缺陷回波和转换模态信号进行分析,即可达到对缺陷准确定位的目的。     

植物纤维素资源的利用

介绍了几种植物纤维素的水解工艺,包括酸法和酶法等,并作了比较,介绍了水解产品的开发,着重介绍了木糖,等几种产品,列出了几条比较经济的水解途径。     

Studies on Saccharification from Alginate using Stenotrophomonas maltophilia

Various environmental factors affecting saccharification from alginate using Stenotrophomonas maltophilia were investigated in flask cultures. The cell concentrations increased from 0.6 to 0.92 optical density (OD) at 660 nm when the agitation rate increased from 15 to 90 rpm. On the other hand, the maximum concentration of sugar was obtained at 3.8 g/l after 4 days of culture at 15 rpm. After 3 days of preculture at 33 °C, the sugar concentration peaked at 5.0 g/l after 5 days of culture. When 10 g/l of NaCl was used, the maximum concentration of sugar, 5.3 g/l, was obtained after 5 days of culture. Yeast extract and peptone were the best nitrogen source for effective saccharification. Especially, the sugar concentration was 6.1 g/l after 5 days of culture using a mixture of 1.0 g/l of yeast extract and 1.0 g/l of peptone.

Under optimum conditions of culture and media, scale-up for effective saccharification from alginate was carried out in 5 l flasks. The cell concentration after 2 days of culture was 0.61 OD at 660 nm and showed no further increase after 3 days of culture. The sugar concentrations from alginate were increased with increasing culture time to 7.9 g/l after 9 days of culture.     

蒸爆技术及其在植物纤维素资源中的应用

介绍了蒸爆原理,类型和几种蒸爆工艺条件。同时还介绍了蒸爆在植物纤维素水解和制无胶板中的应用,此外本文还对蒸爆设备作简要描述。     

超声传质过程机理

简述了超声化学化工的发展历史，在分析声能量与物质间的相互作用形式的同时，论述了超声空化现象的四种物理学效应和四种化工传递附加效应，讨论了超声传质及其对吸收、萃取、结晶、过滤、乳化等单元过程强化的机理。     

Ultrasonic Guided Waves For NDE of Adhesively Bonded Structures

A rather sophisticated guided wave technology is introduced to solve a practical aging aircraft problem of delaminations and/or corrosion detection in either a lap splice joint or a tear strap. A Double Spring Hopping Probe is designed to achieve excellent contact on a curved aircraft structures. A guided wave resonance tuning concept for frequency is also discussed with respect to attaining reliable bond integrity measurements. A variety of experiments are discussed including experiments performed during the field trial on a Boeing 737-222 aircraft.     

长距离超声导波检测应用研究

介绍超声导波理论和传统超声做对比,分析其优缺点。针对不同的管线进行导波检测,从导波的角度出发,探讨超声导波检测技术在石油丁业的前景。     

超声振动对聚烯烃结晶形态的影响--超声细化

利用偏光显微镜(PLM)和DSC对不同频率下的超声波作用聚烯烃的结晶行为进行了研究。结果表明。在一定条件下超声波对聚烯烃的结晶形态和尺寸有较大影响，可以使聚烯烃球晶细化，是控制球晶形态和尺寸的新方法。     

我国超声波处理污泥技术的研究进展

针对我国污水处理厂日趋增多,污泥产量大,处理费用高,污泥处置存在很多问题,阐述了污泥减量化的重要性.超声波处理污泥技术具有污泥减量效果好而且无污染的特点,同时对提高污泥活性,促进污泥消化、脱水以及用于处理污泥的联合效应中也有很好的效果,同时提出了超声波技术处理污泥存在的问题.     

Software for Simulation of Second‐Generation Ethanol Production by a Simultaneous Saccharification and Fermentation Process

Environmental impacts associated with the consumption of fossil fuels and the need to generate power through renewable resources demands the usage of alternative materials. The objective is the production of clean energy from materials like lignocellulosic biomass to produce second‐generation (2G) ethanol. A software in the Matlab program is elaborated to simulate the simultaneous saccharification and fermentation (SSF) process of lignocellulosic biomass for the 2G ethanol production in batch reactors. Studying the effects of the process variables, it was found that the higher interference is caused by cellulose concentration. Higher concentrations of the product in batch processes are obtained with the maximum cellulose concentrations, cells, and enzyme.     

Ultrasonic Guided Waves Scattering Effects From Defects in Adhesively Bonded Lap Joints Using Pitch and Catch and Pulse-Echo Techniques

In this article a method to evaluate defect dimensions in adhesively bonded lap joints based on the measurement of scattering effects of ultrasonic guided waves is presented. A simplified theoretical model is proposed which was initially tested in plates with through holes. The experimental results obtained using both pitch-and-catch and pulse-echo techniques for 500 kHz and 1 MHz frequencies confirm the validity of this model. To evaluate the lap joint defects, a set of samples with artificial defects were manufactured and the form and dimensions were confirmed using C-scan ultrasonic images. With the same methodology used in through-hole analysis, scattering effects of defects were measured. The results obtained with the pitch-and-catch technique with 1 MHz transducers allow us to say that an estimate of defect dimensions could be done by using the proposed model with reasonable accuracy and according with the predictions.     

用超声波进行的石英砂除铁试验研究

采用自行设计的试验装置进行了用超声波技术处理含"薄膜铁"石英砂的试验,得到较好的除铁效果.试验证明,与机械擦洗相比,处理时间可缩短2/3,除铁率提高15%～45%.     

超声波在线检测聚合物加工技术的研究进展

介绍了超声波缓冲杆的研制情况,着重阐述了超声波在线检测技术在聚合物挤出成型、注塑成型以及热固性塑料固化过程的研究概况并,指出了工程生产中实现在线检测的研究重点。     

Current Trends in Pretreatment and Fractionation of Lignocellulose as Reflected in Industrial Patent Activities

The pretreatment process to disintegrate lignocellulose and to fractionate its three main components hemicellulose, cellulose, and lignin, is a crucial step to enable sustainable and economic value chains based on biomass feedstock. This review provides an overview of the recent patenting activities on pretreatment. Most of these activities focus on optimization of different known processes to improve economics, such as increased catalyst efficiency, effluents recirculation, or lignin valorization. However, also a number of patents and demonstration activities based on emerging concepts for pretreatments are observed.     

Effects of Ultrasonic Waves on Vapor-Liquid Equilibrium of an Azeotropic Mixture

Abstract

Azeotropic and extractive distillation techniques used to separate azeotropic mixtures are among the most challenging separation processes in the chemical industry. In this work, an innovative distillation technique which employed ultrasonic waves was proposed to intensify the conventional multi-column azeotropic distillation method into a single-column alternative. The effects of ultrasonic intensity on the vapor-liquid equilibrium (VLE) of methyl-tert-butyl-ether (MTBE)-methanol was investigated at 50, 100, 200, and 250 W/A·cm² and at a fixed frequency of 40 kHz. Studies were also done to examine the effects of ultrasonic frequency on the VLE data at 25 and 68 kHz frequencies. It was found that ultrasonic waves at 50 W/A·cm² intensity and 25 kHz frequency gave the highest relative volatility (α) at 2.654 and completely eliminated the MTBE-methanol azeotrope, thereby allowing highly pure MTBE to be recovered in just a single distillation column. The results revealed that ultrasonic waves had the potential to favorably manipulate α, and hence, the VLE of an azeotropic mixture.     

导波在石化企业高温管道腐蚀检测中的应用

超声导波检测应用的范围与导波激发的原理有关,根据高温管道的特点,选择采用磁致伸缩效应作为高温管道超声导波检测的激发原理。介绍了采用新型基于磁致伸缩效应的导波仪MsS 3030以高温管道的导波检测为例进行的现场检测,同时利用现场测厚验证导波检测的可靠性。结果证明,基于磁致伸缩效应的导波检测可以实现高温管道的在线检测,能有效发现腐蚀等面积缺陷,具有广泛的应用前景。     

超声电解下超细铜粉粒度特性研究

超细铜粉是指粒径介于10-9～10-5m的微小铜粒子,它具有导电导热性能好、粒径小、耐腐蚀、表面光洁、流动性强等特点,在力学、电学、化学和电极材料的制造等领域有许多特异性能和极大的潜在应用价值.在室温下探讨了电流密度、溶液浓度、超声频率以及时间对超细铜粉粒度分布的影响规律,采用扫描电镜对超细铜粉做了物相分析.结果表明:...     

Saccharification of bagasse using a counter-current plug-flow reactor

A method for the simulation of a 3-stage counter-current plug-flow reactor (PFR) for the enzymic Saccharification of alkali-treated (a.t.) sugar cane bagasse is described. The PFR gave higher conversion than a conventional stirred-tank reactor (STR). The STR achieved 44.3% conversion while the PFR achieved 56.4% conversion using 11 % a.t. bagasse after 48 h. The PFR offers potential for more efficient mass transfer and enzyme utilisation, and reduced end product inhibition.     

Study of the Effect of Natural Rubber-graft-maleic Anhydride (NR-g-MA) on the Compatibility of NR-NBR Blends Using the Ultrasonic Technique

The grafted copolymer of natural rubber (NR) and maleic anhydride (MA) was synthesized in a solution state by using ultraviolet radiation. The NR-g-MA was characterized using infrared (IR) technique. The prepared NR-g-MA was added to a 50/50 blend of NR and acrylonitrile-butadiene copolymer (NBR) as a compatibilizer. The effect of compatibilizer (NR-g-MA) concentrations in the range of 2, 4, 5, 6, 8, and 10 wt.% on the ultrasonic velocity, attenuation coefficient, and ultrasonic viscosity was studied in order to study the compatibility of the 50NR-50NBR blend. Ultrasound pulse echo method was used to measure both the ultrasound velocities and attenuation coefficient at a frequency of 2 MHz. Testing for elastic constant, Poisson's ratio, cross-link density, and microhardness was carried out in different percentages of the blend components to study the degree of the compatibility of the blend. The structure of the blend system was established by differential scanning calorimetry. The addition of NR-g-MA to the blend showed improvement of compatibility in certain concentration ranges and deterioration of compatibility in other ranges.     

超声波对微流道中聚合物流动性能的影响研究

为了研究超声波作用下的聚合物材料流动性能及其影响因素,利用自主开发的聚合物超声波辅助挤出测试系统,进行了超声波作用下聚合物熔体在微流道管壁的剪切力、剪切速率和表观黏度的测试,并在与传统稳态挤出相比较基础上,分析了超声波对微流道中聚合物熔体流动性能的影响。实验结果表明,引入超声振动后,微流道的入口压力降有明显降低,并且随着熔体剪切速率的增加而增大;超声振动作用下聚合物熔体剪切速率存在临界值,当剪切速率小于临界值时,超声下聚合物黏度小于传统稳态挤出聚合物黏度,反之,超声聚合物黏度大于传统挤出聚合物黏度。