Application of ultrasonic waves in activation of microcrystalline cellulose

In this work, microcrystalline cellulose (MCC) was activated with ultrasonic waves. The influences of ultrasonic treatment on the changes of supramolecular structures and morphology structure were studied by WAXS and SEM. The accessibility of the MCC was characterized by water retention value (WRV) and specific surficial area. The influence of ultrasonic treatment on the reactivity of MCC was investigated through the reaction of MCC being oxidized into 2,3‐diadehyde cellulose (DAC) by periodate sodium. The mechanism of the reactivity change of ultrasonically treated MCC was examined. The results showed that the degree of crystallinity of MCC decreased and the degree of polymerization showed little change after treatment with ultrasonic waves. The morphologial variation of the treated MCC was significant when compared with the untreated MCC, which contribute to the improvement of accessibility. The aldehyde content of DAC prepared from ultrasonically treated MCC was improved from 64.19 to 85.00%, indicating that the regioselective oxidation reactivity of MCC was significantly improved. The aldehyde content was found to first increase with time of ultrasonic treatment to a point, and then decrease as time progressed. In addition, the aldehyde content was found to increase with an increase in ultrasonic power. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

埋弧自动焊焊接H型钢柱的方法和注意事项

焊接十字形断面柱的结构特殊。对制作工艺及焊接变形控制要求较高。在实际生产中采用预先进行应力消除，组对时不加拘束，焊接时分段同向跳焊的方法成功地完成了对这一构件的制作。     

粘接结构超声信号的小波分解与特征提取

粘接结构因其独特的物理、机械和声学特性在诸多领域具有非常广泛的应用，对于铝合金-橡胶这样一种金属-非金属粘接结构的超声检测信号，本文利用了小波变换的多分辨率分析(时频分析)的方法，有效地提取出了反映多层材料粘接状况的信号特征，该特征提取方法可用在粘接结构的无损检测中。     

Finite element simulation of the mechanics of flat contact pad fretting fatigue tests

An understanding into the macro kinetic and kinematic behaviour of fretted surfaces is provided. Making use of a modified version of a previously developed in‐house two‐dimensional elastic–plastic finite element analysis numerically simulates flat contact pad fretting fatigue tests. Basic macro mechanics concepts are adopted to idealise two bodies with rough contact surfaces and loaded at two different sites with arbitrary axial loading profiles. A time scale factor is devised to recognise the earliest candidate out of the events possibly accommodated at each loading increment. The present analysis utilises a relevant experimental set up developed in the Structural Integrity Research Institute of the University of Sheffield as an application. Computational results accurate to within 1.2% and corresponding to one contact pad span and six constant normal loads acting individually with four amplitudes of two sinusoidal axial load cycles are presented. The present computations include (1) the development of the global and local normal and tangential reactions and relative sliding displacement acting along the fretting surfaces and (2) contact pad deformation, generated stress fields and plasticity development within the neighbouring region of the fretted area.     

WDB620高强钢应用于大型蜗壳的焊接制造工艺研究

2005年初,水电十四局承担了漫湾二期水电站和小湾水电站蜗壳的制造任务。蜗壳钢材选用国产600 MPa级别高强钢,为了全面综合地考核该级别钢种的材料强度和安全裕度,检验模拟大型蜗壳焊接制造工艺的可靠性。对国产的WDB620高强钢进行了可焊性和制造工艺性试验研究,并在国内首次设计、制造模拟压力容器并对其进行水压试验和爆破试验。研究成果通过中国水电集团公司鉴定,结论为该课题研究成果达到国内选进水平。     

劈刀和肋环夹持工况对超声键合换能系统电学特性的影响

通过实验分析了肋环夹持松紧度和劈刀存在两个因素对超声键合换能系统电学导纳特性的影响规律。对换能系统在悬挂有无劈刀和夹持8个松紧度等各个情况下进行谐振频率附近的导纳圆测量,确定换能系统等效电路各特征参数的变化情况。由实验结果的分析可知,劈刀的附加质量以及肋环松紧程度对换能系统谐振频率的影响不大,但劈刀的存在改变了换能系统的能量分布和耗散,是影响换能系统各特征参量的主要因素之一。这些结论有助于超声键合换能系统的优化。     

超声监测技术在膜分离过程中的应用研究

在膜分离过程中，膜通量总是随运行时间而下降．为了区分膜污染与浓差极化或者可能的膜形变对通量的影响，和选择适宜的清洗过程，对一种只敏感于膜表面状况的超声测量方法进行了广泛研究．通过平板膜(包括微滤膜、超滤膜和反渗透膜)以及卷式反渗透膜过程的应用实例，说明了这种实时、在线的超声时域反射法即Ultrasonic Time-Domain Reflectometry (UTDR)可以利用它的反射波的振幅和回声抵达超声传感器的时间来监测浓差极化、膜污染(例如CaSO4污染)与清洗过程，也可以用来测量膜的压紧度和污染层厚度．超声测量与传统膜性能测量结果有良好的关联，并具有区域性测量的特性．为了实用化目的，新近的研究进展也作了介绍．     

一种矿山用钢筋网自动化焊接生产线的设计

设计一条钢筋网自动化焊接生产线，包括经料送料平台、纬料自动分料及上料机构、多点电阻点焊机、接料平台、卸料机械手。从上料到出料依靠电机、汽缸之间的协调工作来实现。并由单片机和PLC实现控制功能，上位机用MCGS组态软件在整个过程监视现场，采集工作状态及参数，起到监控作用。     

多相流动超声波测井模拟实验研究

油田油井动态监测的实质是准确地测量各生产层位的流量和含水率，为此研制了超声波三相流量测试仪。利用该仪器测量油、气、水多相流动的各相流量，通过模拟井动态实验验证了该测井方法的可行性，适用于我国90％以上的生产井．克服了现有国产仪器不能测气和用集流伞下井测量等缺点。     

B4 用染色法记录液体中大功率超声场的分布

利用染料在纸上染色可以方便，快速地记录液体中大功率超声场的分布，本文给出这一套验研究的结果，表明该方法在声化学和超声清洗等大功率超声液体处理应用中，对于测量空化强度的空间分布是一种实用，可取的方法。