Key Engineering Materials Vols. 419-420

Abstract: A Finite Capacity Planning Policy (FCPP) is developed for multiple color filter (CF) fabs where each fab has several identical production lines. FCPP assigns customer orders to multiple fabs and multiple lines by taking into account each fab’s available capacity and Work-In-Process (WIP) level, as well as each order’s batch size, product type, process routing, and processing time. After all orders are assigned to fabs and lines, order release time and finish time are determined by the implementation of several modules. FCPP is developed in Microsoft Visual Basic for Application (VBA), and an AutoMod simulation model is also developed. A company with two CF fabs and two lines at each fab is treated as a case study, and industrial data from these fabs are collected and used to evaluate the performance of FCPP based on the design of experiments. Preliminary simulation results show that FCPP can effectively and efficiently balance the loading between fabs and also balance the loading between lines in each fab.

Abstract: Facility planning is crucial to the performance of array fabs in Thin Film Transistor - Liquid Crystal Display (TFT-LCD) industry. In order to avoid costly changes and modifications of fab layouts at the installation or production stages, the designers should carefully evaluate design alternatives and then select the best one during the design stage. A TFT-LCD manufacturing process consists of four basic processes: array, color filter, cell, and module. This research proposes an Array Fab Design Procedure (AFDP) to conduct quick calculations to develop and evaluate initial design alternatives for TFT-LCD array fabs. A series of practical formulae are presented to sequentially determine the related design parameters. The proposed AFDP provides a basis for rapid modeling and evaluation of array fab designs. AFDP is developed in Microsoft Visual Basic and data from real array fabs are used to demonstrate its effectiveness and efficiency. Results indicate that AFDP can quickly calculate the related fab design parameters. “Job shop with small bays” leads to the least average sheet moving distance. With AFDP as a tool, fab designers can evaluate design alternatives and conduct what-if analysis in the initial phase of fab design.

Abstract: Different from dexterous robotic hands, the gripper of heavy forging manipulator is an underconstrained mechanism whose tongs are free in a small wiggling range. However, for both a dexterous robotic hand and a heavy gripper, the force closure condition: the force and the torque equilibrium, must be satisfied without exception to maintain the grasping/gripping stability. This paper presents a gripping model for the heavy forging gripper with equivalent friction points, which is similar to a grasp model of multifingered robot hands including four contact points. A gripping force optimization method is proposed for the calculation of contact forces between gripper tongs and forged object. The comparison between the calculation results and the experimental results demonstrates the effectiveness of the proposed calculation method.

Abstract: The ship-based helicopter is always dangling in the sea because of winds and waves. It is necessary to analyze and calculate the mooring of helicopter. In order to void the complex derivation of mathematical formulas, the parameterized finite element method (FEM) model about the ship-based helicopter body, mooring cable and mooring base is established with the software ADAMS. This model is used to calculate the mooring tension and optimize the locations of the mooring bases. In the various layouts of the mooring bases, the minimal mooring tension is the layout optimization object. After some added constraint conditions are considered, the mooring point coordinates are searched and calculated in the standard and nonstandard parking positions with subproblem approximation method. Through the comparison and analysis of the relative changing ratio of the position coordinates, the final optimization layout scheme is obtained.

Abstract: Amplitude Domain Processing (ADP) is proposed in this paper for modern and complicated electromagnetic environment; the algorithm is derived from Locally Optimum Detection (LOD) theory. In non-Gaussian noise environment, ADP technique could be used in Squared-Sum Detector to obtain a new code acquisition method. The result of simulation shows that the Amplitude Domain Processing proposed by this article could eliminate the narrowband interference in Spread Spectrum Navigation Receiver automatically and improve its SNR (Signal to Noise Ratio).

Abstract: . A novel method for layout has been proposed for control panel. Six layout principles of ergonomics are taken into consideration to reduce the influences of indeterminate factors caused by the subjective judgments of designers. Optimization method and function is constructed to optimize the layout result based on genetic algorithm. And a computer-aided layout system is developed based on UG/OPEN API to realize automatic layout by computer. A detailed example of control panel layout of a thermal power plant is provided. The result shows that the efficiency and quality of layout are improved by this method.

Abstract: Conventional engineering parts usually composed by algebraic surfaces are important investigation objects of reverse engineering. In this paper a step segmentation method for algebraic models is proposed. The mesh normals and curvedness of every vertex are estimated as a shape descriptor. In the first segmentation fourteen directions are chosen initially, and a k-means algorithm according to the normal vectors is used, then the surface is divided to form patches by a region-growing scheme, as well as some sharp edges or flat areas are detected. In order to identify algebraic surface, curvedness of a patch is set as the criterion by which the surface merged into near constant curvedness region. Especially a novel mean shift algorithm is adopted in this method, that a powerful technique for clustering in image process, and is extended to normal filtering while preserving the features to increase robustness of the method. Experimental evaluations using scan data or noise data demonstrate the efficiency of the proposed method.

Abstract: A robot used for industrial spot welding is a 4-DOF serial mechanism, it can be applied to some special industries. There are multi via points known in path, each joint value can be accurately solved by the inverse kinematics. The quintic polynomial interpolation was adopted between each two adjacent desired via points, the continuous trajectory is formed in accordance with the time course. The simulation model is developed using SimMechnics, the movement parameters and path are obtained by simulating, the simulation results indicate that the motional parameters and path can be accurately and effectively obtained for robot analysis and design.

Abstract: In this paper a magazine layout optimization model with performance constraints is described and the objective function and its constraints of magazine layout are established. A multiobjective optimizations layout model based on polygon method is put forward. The model deals with a series of constraints such as geometry constraints, in-and-out point position optimization, magazine capacity and system reliability and safety. An improved genetic algorithm (GA) is proposed in this paper based on the new encoding scheme and logical mutation operator. The algorithm solved the problem of multiobjective layout design with performance constraints.

Abstract: An Ocean Casing Pipes Centering Equipment is designed and implemented. Utilizing the equipment, two casing pipes can be fastened together by means of welding. The equipment can automatically carry out clamping and centering two casing pipes, and then the butt welding is conducted at their adjacent ends. In the development of this equipment, some advanced means, such as digital modelling and FEA (Finite Element Analysis), are taken full advantage of. First, all the parts’ 3D models are built with Pro/Engineer. Then, those digital parts is assembled in Pro/E assembly environments. Meanwhile, assembly interference detection is executed. Furthermore, by means of universal finite-element software，the finite element model is constructed. The strength and stiffness of the structure is calculated and analyzed so that the faults of the equipment can be found out in design stage. Through repeating this designing and verifying course, the structure of the equipment can be improved.