Papers by Keyword: Process Control

Abstract: Tetramethyl ammonium hydroxide (TMAH) has wide applications in semiconductor industry, including photoresist development, silica etching (especially Sigma etching), and wafer cleaning, etc. One of the critical areas of the photolithography process is the development of unexposed (negative) or exposed (positive) photoresists without pattern distortion. As a metal free, basic aqueous solution, TMAH is the most common positive photoresist developer providing no metal contaminations. The bath composition, especially the concentration of TMAH, is strictly controlled within the process specifications (~2.2 to 2.4 % (w/w)), since it greatly affects the developing rate and contrast [1]. Traditional monitoring of TMAH concentration does not suffice for the modern needs of a sub-20 nm IC fabrication process. Additional critical parameters include dissolved carbonate and proprietary surfactants.

Abstract: With regard to the climate change as well as the shortage and increase in price of natural resources, efficient resource management becomes more and more important, also for production processes. More than half of the sheet metal used in the automotive industry is wasted. Considering the amount of energy and the added value associated to the discards, enormous savings are possible. The approach of this research work is to avoid waste during a forming process by means of a continuous process monitoring and a self-learning intelligent tool interacting with the servo press. The flexibility of the servo press, which is so far used to optimize the single press stroke, only, shall be exerted to respond on altering material properties of blank sheets and the thereby changing forming behaviour. The sample process includes a two-tiered bending process, in which a conventional punch performs the pre-bending in the first step and an independent servo axis the compensation-bending in the second step. If an inadmissible bending angle is measured after the second step, the servo press stops automatically and the additional servo axis performs a teaching-stroke to adjust the compensation angle. After that, the continuous process starts again. This paper presents the springback compensation strategy which uses flexible correction algorithms based on data of the on-line process monitoring as well as data of the previous bending steps. Finite Element Analyses are carried out to validate the strategy.

Abstract: Grinding process is a critical procedure of mineral process, and its running character is extremely important for the productivity and quality improvement. It is of comprehensive and complicated characteristics of nonlinearity, large time-delay, slow time-varying and so many key engineering parameters which can not be detected online. It is dramatically significant and difficult to study the control algorithms, the optimization algorithms and the soft censor techniques for grinding process. In order to decrease the cost and risk of practical debugging, how to establish a control simulation system of grinding process for engineering is an issue which has greatly practical value. The simulation experiment platform for grinding process control is designed and developed. The general structure of the platform including real control system and virtual production plant is proposed. Thus, a kind of engineering experiment environment is provided for control and optimization algorithms.

Abstract: The objective of this paper is to highlight the use of a two-dimensional (2D) sustainability index in performing a sustainable integrated process design and control (Sustain-IPDC) for a continuous-stirred tank reactor (CSTR) system. Sustain-IPDC for a CSTR system is formulated as a mathematical programming problem and solved by decomposing it into six sequential hierarchical sub-problems: (i) pre-analysis, (ii) design analysis, (iii) controller design analysis, (iv) sustainability analysis, (v) detailed economic analysis, and (vi) final selection and verification. The proposed methodology is applied to the production of cyclohexanone using a CSTR. The results show that the proposed methodology is capable in finding an optimal solution for a CSTR design problem that satisfy design, control, sustainability and economic criteria in an easy and systematic manner.

Abstract: The process control virtual laboratory is created by using LabVIEW for demonstrating process control via manipulating a simulated model of a physical process. In this study, a system of convection heat transfer in a rectangular duct is set up and connected with a data acquisition card and a computer serving for an advanced virtual laboratory aimed at supporting teaching and learning in Instrumentation and Control Engineering courses at Pathumwan Institute of Technology. The use of the virtual laboratory facilitates the ongoing evolution of the teaching method from a traditional didactic lecture and laboratory course to a more student-centered approach. The LabVIEW application is used to conduct several tasks including user interface design, publishing and sharing measured data, instrument control and remote access to a system in the Process Control Laboratory. Using LabVIEW software, students can familiarize the basic skills necessary to use equipment and software because the control systems in many industrial processes can be implemented on a computer which runs on LabVIEW.

Abstract: As the use of automation increases in the manufacturing industry as well as other industrial environments, more programmable logic controllers (PLCs) are used in these areas to increase reliability and flexibility, reduce cost, and increase maintainability. In this proposed paper, a basic of PLC in automation environments is introduced and a bottle filling and packaging process control implemented by using Allen Bradly CompactLogix PLC is discussed.

Abstract: This paper introduces a novel on-line real-time monitoring system for acidic emission produced by acid pickling, which has been one of the greatest contaminant and major harness content. The system can monitor the HCL concentration in exhaust fumes on-line, and realize the real-time analysis and transmission of the acquisition data. HCL wet chemical sampling system form the whole on-line monitoring system. HCL wet chemical sampling system consists of integrated air velocity transducer, chloride ion analyzer, wet chemical sampling device and liquid level measurement device. It aims to collect HCL fog sample and convert the sampling analogue signal to digital data that can be analyzed. The system overcomes the influence by high temperature, high humidity and high concentration of dust. It realizes the monitoring, storage, analysis, warning and transmission of HCL concentration data in the exhaust. It is beneficial in practical industrial field and environmental protection.

Abstract: The process control system for tandem cold mill is the core of the production line control system. Its operating status influences the stable production of strip directly. In this paper a tandem cold rolling process control system of cold-rolled sheet plant was taken as an object, the structural framework of control system was designed, the composition and function was introduced.

Abstract: Mechanisms of the distortion of deep excavation in soft clay are recommended on the beginning. Plane FEA method is combined with back-analysis from displacement on this paper to establish a dynamic prediction system of the distortion of deep excavation, which is proved to be viable by practice. Combining with the idea of process control, a process control model of the distortion of deep excavation is established on this paper. It is divided into three parts: advance control, observation and dynamic prediction, process control in the construction.

Abstract: In this paper, a control methodology for nonlinear interacting system is developed, in which the PID controller is implemented by neural networks trained by mean square error (MSE) criterion. The mean square error can be estimated recursively by utilizing receding horizon window technique. The measurable disturbances in nonlinear interacting system are input to the Neuro-PID controller besides the sequences of tracking error and hence the feed-forward control is combined with feedback control in the developed scheme. The applicability of the developed control scheme is demonstrated on Two Conical Tank Interacting Level System (TCTILS) which exhibits dynamic non linearity and coupling dynamics. Simulation results show that the developed control scheme realized a good dynamic behavior of the TCTILS and a perfect level tracking.