Ultrasound-promoted green synthesis of 1,4-dihydropyridines using fuctionalized MWCNTs as a highly efficient heterogeneous catalyst

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.     

A new ultrasonic measurement system for the cure monitoring of thermosetting resins and composites

Measurements of the ultrasonic sound speed of thermosetting resins and composites can be used as an in-process cure monitoring technique. Ultrasonic measurements have an advantage over other in-process techniques in that ultrasonic sensors do not make contact with the part (thus leaving no imbedded sensor or witness mark) and can make true bulk measurements of the part. A new commercially available ultrasonic cure monitoring system has been developed which easily enables ultrasonic measurements to be made in compression molding, resin transfer molding, and autoclave processes. Advancements in ultrasonic sensor technology enable the sensor to maintain good coupling to the part during thermal cycling to 260C. Data is presented showing the change in ultrasonic sound speed during the compression molding of a graphite-epoxy prepreg. The data shows a good relationship to the ionic conductivity and resistivity data collected via dielectric cure monitoring.This effort was sponsored by the Manufacturing Technology Directorate, Wright Laboratory (WL/MTX), Air Force Material Command, USAF, under cooperative agreement award(s) to NCMS. The U. S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of Wright Laboratory or the U.S. Government.     

Lamellar metal-organic complex and its rod-like nanoparticles prepared with ultrasonic technique

Metal-organic complex (H3NCH2CH2NH2)3[MoO2(OC6H4O)2] with a lamellar morphology has been syn- thesized. Its crystal structure was confirmed by single-crystal X-ray diffraction. The morphology of the crystal was observed by scanning electron microscopy (SEM). The metal-organic nanoparticles have been prepared by using an ultrasonic method. The morphology of the as-prepared nanoparticles was observed by transmission electron microscopy (TEM). The possible formation mechanism has also been proposed.     

声表面波检测铝板表面微缺陷深度实验研究

为了探究声表面波与不同深度微裂纹缺陷相互作用的关系,将脉冲激光作用于一系列不同缺陷的试件铝板上进行线光源激励,激发激光超声波。用超声传感器接收在铝板中传播的激光超声信号,通过数字荧光示波器采集激光超声在铝板中的传播数据。对采集到的反射波数据进行分离谱分离过程得到的铝板中激光超声的时域分布和透射波数据进行频域分析。实验发现:缺陷深度影响着反射回波两峰值特征点到达时间差,两者之间近似线性关系,也影响着透射波的截止频率且二者呈现递减关系。     

超声光栅测液体声速原理和实验

本文对用超声驻波自身像法和超声光栅衍射法测定液体声速的原理进行了分析,并介绍了其实验方法     

Dynamic mechanism and its modelling of micromachined electrostatic ultrasonic transducers

A tensile-plate-on-air-spring model (or called TDK model for short) for micromachined electrostatic ultrasonic transducers has been developed based on a thorough investigation of their dynamic mechanism. The mechanical stiffness effects caused by the compressibility of air gaps, bending stiffness of the diaphragm and in-plane tension applied to the diaphragm, together with an electrostatic negative stiffness effect are included completely in the model. Desired particular fundamental frequency and bandwidth can be obtained by only properly tailoring the geometry, dimensions and materials of transducers according to the model, which provides thereby a reliable theoretical basis for the understanding and optimised design of such transducers. Project supported by the National Natural Science Foundation of China (Grant No.69974001).     

超声波对材料力学性能影响实验研究

研究超声波作用下材料的特殊力学行为,建立一套超声波作用对材料影响的实验系统,通过对紫铜和低碳钢试件的实验研究,给出材料特性变化的实验数据,并利用其对这些特殊现象的形成机理进行初步探讨。     

Optimization of travelling wave ultrasonic motors using a three-dimensional analysis of the contact mechanism at the stator–rotor interface

The present paper investigates optimization rules and new design methodologies dealing with the contact mechanics in rotative travelling wave ultrasonic motors (TWUM). The proposed approaches focus on the design of the rotor, including the friction layer that is usually deposited onto its lower surface, while the stator is supposed to be preliminary designed. Contact aspects such as the transmission of mechanical power as well as the wear mechanism of the friction layer are investigated, according to the analysis of the stator–rotor contact mechanics in both hoop and radial directions. Considering a classical wear criterion in a preliminary step, a contact ratio, that allows the mechanical power to be optimized, is pointed out in the hoop direction. In a further step, the contact conditions in the radial direction are improved through the elastic fitting of the stator and rotor radial deflexions, therefore allowing the material's wear to be decreased. Some experimental tests, that have been recently performed, give a comparison of wear marks, which occur onto optimal and non-optimal rotor geometries. A first mechanism synthesis is finally proposed in such a way to allow the mechanical architecture of the rotor (including the friction layer) to be automatically designed according to a given set of mechanical constraints.     

Non-linearity parameter B/A of binary liquid mixtures at elevated pressures

When sound waves of high amplitude propagate, several non-linear effects occur. Ultrasonic studies in liquid mixtures provide valuable information about structure and interaction in such systems. The present investigation comprises of theoretical evaluation of the acoustic non-linearity parameter B/A of four binary liquid mixtures using Tong and Dong equation at high pressures and T=303.15 K. Thermodynamic method has also been used to calculate the non-linearity parameter after making certain approximations.     

涂膜超声及涂膜电解对固体表面铀的去污研究

制备了高分子可剥离去污膜液,确定了涂膜液中各组分最佳含量,对固体表面核素的去除研究结果表明：在金属表面采用涂膜电解去污、非金属光滑固体表面采用直接涂膜去污、非金属粗糙固体表面采用涂膜超声去污工艺,其去污率均可达99％以上,优于其他方法。