利用弯矩影响线的移动荷载识别方法

基于模态叠加理论,通过桥梁多个截面处加速度响应数据,计算得到桥梁受移动荷载作用下的模态加速度.根据d'Alembertian原理,桥梁截面任意时刻的动弯矩可看作是任意时刻受惯性分布力和移动荷载作用下的静弯矩.利用影响线,建立起移动荷载与弯矩之间的关系,提出了一种利用弯矩影响线识别移动荷载的方法.算例表明,当荷载只有一个时,可由单点弯矩直接识别,当有多个移动荷载时,可基于多个截面的弯矩数据,利用最小二乘法可以有效的识别出任意时刻作用于桥梁上的移动荷载值.该方法避免了求解桥梁的动力学微分方程,识别精度高且过程简单,适合于工程应用.     

Initial bond formation in thermosonic gold ball bonding on aluminium metallization pads

The morphological features of lift-off footprints on the aluminium metallization pads were investigated to gain an understanding of the effects of bonding parameters on formation of initial bonds during thermosonic gold ball bonding. The obtained results showed that metallurgical bonding initiated at the peripheral areas of the contact area situated along the direction of ultrasonic vibration. Those areas extended inwards with an increase in ultrasonic power. Both the external bonded area and central non-bonded area increased with increasing bonding force. Based on the evolution of footprints, the bonding models were proposed, and the effects of the bonding parameters on the formation of initial bonds were discussed.     

A model relating tool torque and its associated power and specific energy to rotation and forward speeds during friction stir welding/processing

Torque (M) is a very important quantity in the friction stir welding (FSW) process but a satisfactory model relating M to the two major FSW parameters, rotation speed (ω) and forward speed (v), has not been well developed. In this work, a better model of the form, M=f(ω, v), was sought. Experimentally, FSW of an aluminium alloy was conducted over a wide range of ω and v values and M was measured. An exponential decay function has been found to fit all the M versus ω data well and is meaningful for any ω value. The effect of v on M can approximately be accounted for through linearly relating the model parameters to v. The model allows for a detailed evaluation of the sensitivity of M to changes in ω and v. The model decay and the pre-exponential parameters need to be adjusted to make predictions for different aluminium alloys in the low ω range. Both the model and experimental data demonstrate a diminishing alloy effect on material flow resistance as ω increases. Furthermore, models of tool power (P_Tool) and specific energy (E_s) can be derived from the model for M and give predictions that are also meaningful over the entire range of ω values. Finally, the dependences of P_Tool and E_s on ω and v and the relationship between E_s and the processing zone temperature will be discussed.     

Mechanically strong conducting hydrogels with special double-network structure

Mechanically strong conducting hydrogels composed of poly(acrylamide) (PAAm) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) have been synthesized through the construction of a special double-network (sDN) structure. The novelty of the sDN hydrogels lies in the introduction of PEDOT-PSS semi-interpenetrating polymer network (semi-IPN) hydrogel as the second network. Based on the experimental results and the double-network theory, an additional strengthening effect resulting from the formation of the PEDOT clusters in a three-step fracture process is proposed. The applicability of as-prepared PAAm/PEDOT-PSS sDN hydrogels in electromechanical actuators is also briefly discussed.     

泥浆泵输污管路系统的合理化改造

安阳钢厂高炉煤气洗涤循环水处理站的泥浆泵输污管路系统在运行过程中,泵体及污泥输送管路系统经常发生吸气、振荡和堵塞的不良现象,经现场调查和理论分析,认为吸水、压水管路不合理的布置及相关设施的不完善是造成泵体不能正常运行的主要原因,同时给操作管理带来一些不便。通过进行一系列改造,如对吸水、压水管路增设有益、取消多余管件;把吸水管路分设,改普通弯头为三通弯头;减少压水管路的转向次数,选择大转弯半径的弯头,降低管线总长和增置高架流槽,不仅使系统运行更安全可靠、稳定高效,并且让操作管理和维修养护更方便,还节省了不必要的开支。     

四氟化碳生产技术与市场

介绍了四氟化碳的性能、用途和生产技术路线。评述了其国内外的市场变化、主要生产厂家规模及分布,从四氟化碳发展历程到今后趋势,说明四氟化碳在氟化工中的地位、我国发展四氟化碳的优势与不足。对打算进入此产品项目的企业,从技术开发、项目投资、产品生产销售等方面提出了建议。     

《工业水处理》质量与学术影响力分析

依据中国知网开发的中国期刊全文数据库、中国引文数据库及中国科学院开发的中国科技期刊引证指标数据库,采用文献计量学方法对《工业水处理》杂志2004—2008年的载文、引文,2004—2007年的被引、学科影响力等进行调查研究及定量分析,客观揭示该刊在我国学术界的整体水平及主要影响。以期对期刊的发展提供客观依据。     

钢铁企业净循环冷却水系统设计

详细介绍了为某钢铁企业服务的敞开式净循环水系统的设计过程。包括工艺流程的选择、工艺参数的计算、主要设备的选型等。设计采用事故水塔和柴油机泵联合供水方式确保系统安全,并将仪表检测的参数进行集中显示和控制。系统自动化水平高,运行维护方便。     

Weld line transverse energy density distribution measurement in laser transmission welding of thermoplastics

While laser beam profiling techniques are available for the measurement of a laser beam power profile, such techniques are difficult or impossible to use in order to characterize the power profile of the beam which has passed through the light-scattering semi-crystalline polymer (such as nylon). This paper presents a technique for measuring the scattering of the laser beam caused by the laser-transparent part in laser transmission welding. The technique is easy to implement and does not require specialized or expensive equipment. It relies on measurements of line widths for a sequence of lines left on the polymer surface by a rapidly moving laser beam at progressively increasing powers. The line width and power information is then used to obtain the distribution of the laser energy across the weld line. An application for a case of a high-power diode laser and (glass-reinforced and natural) polyamide 6 is presented.     

一种基于交点质心求解的RSSI定位算法及其优化

为了提高RSSI算法的定位精度,提出了一种新的基于交点质心求解的RSSI算法.此方法用矩阵求解多组二元二次方程组,得出的结果为这些方程组解的平均值,定位坐标由这些平均值确定.相比于传统最小二乘法,交点质心法的定位精度明显提高,并给出了两种优化方案,最后提出了一种实现三维定位的方法.