Process-oriented Monitoring Techniques

The overall structure of the proposed framework is shown in Figure 1. Client-Server structure is used to design the system where PHASuite is built as a server and process monitoring module is a client. Therefore, PHASuite can be used offline or online depending on the situation. The complete system has been developed using C++ running under Windows system. Object-oriented programming techniques were used for the development of the system. 

In process control systems it is essential to develop rapid on-line monitoring techniques to acquire structural parameters such as crystallinity, and orientation. By controlling these structural parameters the end use properties may be influenced which are essentially defined by these parameters. In order to use laser Raman spectroscopy for such purposes, calibration systems need to be developed using an independent technique. 

The analytical procedures for Level 3 are specific to selected components identified by Level 2 analysis and are oriented toward determining the time variation in the concentrations of key indicator materials. In general, the analysis will be optimized to a specific set of stream conditions and will therefore not be as complex or expensive as the Level 2 methods. Both manual and instrumental techniques may be used, provided they can be implemented at the process site. Continuous monitors for selected pollutants should be incorporated in the analysis program as an aid in interpreting the data acquired through manual techniques. The total Level 3 analysis program should also include the use of Level 2 analysis at selected intervals as a check on the validity of the key indicator materials which reflect process variability. 

The mechanical properties of the nanocomposites strongly depend on their structure, orientation of the filler, phase separation, and processing conditions. Hence, there is a need for in situ nondestructive characterization technique to probe the internal stress in nanocomposite structures. The shortcomings of many conventional techniques such as low resolution, destructive measurements, complex modeling and applicability to only certain class of materials are overcome by using pRS owing to the sensitivity and nondestructive measurement for monitoring internal stress in various materials [59]. 

The "jump" technique, used by Tabor tt at. [18,19], measures the adhesion ascribable to van der Waals forces when two thin cylindrical sheets of mica oriented at right angles approach each other. Approach is controlled by a piezoelectric transducer and the separation of the two sheets is measured by interferometric fringes of equal chromatic order. The specimen not driven by the piezoeletric transducer is held in position by a sensitive cantilever spring. At some critical distance of approach the attractive van der Waals dispersion forces increase faster than the counterforce of the deflected spring and the two specimens flick into contact, a process which is monitored by the interferometric fringes. No external forces are applied to establish contact. 

Well-known and documented techniques exist to monitor product variation while it is within the producer s environment. Most of the techniques require the observations or data to be statistically independent. That is, the data for a specific performance measurement are assumed to have no relationship to prior or successive observations. It is assumed that no correlation exists between data collected prior to or following a specific observation. The techniques used to monitor such data are collectively called statistical process control (SPC). These techniques are utilized in consumer-oriented industries. Some of the more prominent or useful techniques are presented in this chapter. Specifically, seven tools for SPC are reviewed, and their applicability is examined. Furthermore, common and improved approaches for process capability analysis are presented. 

In this technique the sample is subjected to a constant electric field and the current which flows through the sample is measured as a function of temperature. Often, the sample is heated to a high temperature under the applied field and then quenched to a low temperature. This process aligns dipoles within the specimen in much the same way that drawing a material under a mechanical stress would bring about orientation of molecules in the sample. The polarisation field is then switched off, and the sample is re-heated whilst the current flow resulting from the relaxation of the induced dipoles to the unordered state is monitored. 

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