Papers by Author: Li Jia Feng

Abstract: Developing automatic assembly techniques is essential for the application of advanced nanomaterials such as carbon nanotubes (CNTs). This paper presents a review of current research progress towards the automatic assembly of CNTs by dielectrophoresis (DEP). The mechanisms and experimental set-up of three methods for controlled DEP assembly of CNTs are introduced. One is using a limiting resistor to control the electric field after the deposition of a single CNT or a bundle of CNTs. The other two measure electrode gap electrical signals, gap impedance and current respectively, indicating CNT connections to stop the DEP process. The real-time electrical signal monitoring during the DEP process and controlling the DEP using the detected signals represent a research direction in the manipulation of a wide category of nanomaterials and will speed up the industrial applications of the materials.

Abstract: Parameter optimization in multi-pass cutting operations involves optimal selection of cutting speed, feed rate, depth of cut, and the number of passes, duo to significant influence of these parameters on the quality of machined parts and machining economics. In this paper, a non-linear mathematical model based on minimum production cost for multi-pass milling operations is presented. The unwanted material is removed by one finishing pass and one or multiple roughing passes depending on the total depth of cut. Various realistic constraints are considered when developing the model. Optimal values of machining parameters are found by Genetic Algorithms. An example is presented to illustrate the optimization model and solution approach. The method yields lower unit production costs compared with the results from the literature and machining data handbook.