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Sculptured parts, characterized by interconnected and bounded parametric surface patches, are widely used in aerospace, automobile, shipbuilding and plastic mold industries due to their functional and aesthetic properties. However, adoption of these sculptured surfaces on mechanical products increases the complexity of manufacturing and puts forward a challenge to achieve high machining quality and productivity, as well as low machining cost. Machining of sculptured parts is mostly carried out on a milling machine. The milling process can be divided into: rough cut (roughing) and fine cut (finishing) operations. Rough machining is used to remove excess stock material, while finish machining is aimed at generating adequate tool paths for producing the final shape of the part. When a sculptured part is machined from prismatic stock, a large amount of rough cut, up to 90 percent of the total machining, is required. Cutting time reduction in rough machining can considerably improve the efficiency of sculptured part machining, lower production cost. This research focuses on the productivity improvement of sculptured part rough milling machining that is affected essentially by CNC tool path and machining parameters. Two major strategies, machining path strategy and machining parameter strategy are investigated. A number of new methods are introduced to generate highly productive CNC tool path and machining parameters. Study on machining path strategy involves approaches of generating 2½D CNC tool path trajectory, creating new tool path patterns, and automatically identifying optimal tool path pattern. While research on machining parameter strategy focuses on the minimization of cutting time, based upon the changing part geometry during machining and manufacturing constraints. A method that incorporates an existing milling process model into the cutting parameter optimization to predict instantaneous cutting force and identify the most effective cutting parameters is introduced. An improved model cofficient determination scheme using numerical optimization and artificial neural network techniques is developed, and extensive cutting tests are carried to allow the milling process model to fit into the cutting parameter optimization. A method for the automated formulation and solution of the cutting time minimization problem is also introduced to allow important machining parameters, including the number of cutting layers, depth of cut, feed rate and cross-cutting depth, to be determined without human intervention. The research directly contributes to automated sculptured part machining, and has a great potential to produce significant economical benefits to manufacturing industry. The study also establishes a platform for further research and development on intelligent sculptured part machining. / Graduate

Being among the most popular and efficient classification and regression methods currently available, implementations of support vector machines exist in almost every popular programming language. Currently four R packages contain SVM related software. The purpose of this paper is to present and compare these implementations. (authors' abstract)

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Interest is continually being shown in the replacement of variable speed DC machines with an equivalent inverter fed AC machine. This is as true in the field of highly rated machines for traction use. as in the field of smaller industrial drives. In the following work, a general design method is presented that is suitable for the design of induction, and slip ring synchronous machines of the round rotor or salient pole type. The method is based upon machine models that employ surface quantities. This type of model clearly displays the interaction between flux and current, and is readily adaptable for design use. as the amount of detail required is kept to a minimum. Several designs are presented for induction and synchronous machines that satisfy the requirements of a traction motor for use in a high speed locomotive. Performance predictions, based on sinusoidal supply considerations and operating under two commonly used control schemes are shown. The traction motors satisfy the main overall requirement for a minimum size and weight design. In practice the AC traction motors would be supplied by a variable frequency inverter. In view of this, an analysis of the performance of the most suitable induction and synchronous motor designs is presented, when each is being supplied with an inverter of the preferred type. Two inverters are considered, one of the constant voltage type, and one of the constant current type. Computer models are used to predict the machine, voltage current and torque waveforms when both inverters are operated In the 120 degree conduction mode. Experimental results are shown, to verify the computer model of the current source inverter. A 5KVA laboratory squirrel cage induction machine is used for this purpose, in conjunction with a force measuring platform that enables the steady state torque pulsations to be recorded.

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Thesis (M.B.A.)--Boston University