Database subsystem

Historical DataBase Subsystem We have discussed the use of on-hne databases. An historical database is built similar to an on-line database. Unlike their on-line counterparts, the information stored in a historical database is not normally accessed directly by other subsystems for process control and monitoring. Periodic reports and longterm trends are generated based on the archived data. The reports are often used for long-term planning and system performance evaluations such as statistical process (quality) control. The trends may be used to detect process drifts or to compare process variations at different times. 

In this approach accident cases and design recommendations can be analysed level by level. In the database the knowledge of known processes is divided into categories of process, subprocess, system, subsystem, equipment and detail (Fig. 6). Process is an independent processing unit (e.g. hydrogenation unit). Subprocess is an independent part of a process such as reactor or separation section. System is an independent part of a subprocess such as a distillation column with its all auxiliary systems. Subsystem is a functional part of a system such as a reactor heat recovery system or a column overhead system including their control systems. Equipment is an unit operation or an unit process such as a heat exchanger, a reactor or a distillation column. Detail is an item in a pipe or a piece of equipment (e.g. a tray in a column, a control valve in a pipe). 

Figure 6. Example of the levels of the process as used in the CBR database. (0 process, 1 = subprocess, 2 = system, 3 = subsystem, 4 = equipment, 5 = detail).

The retrieval of cases can be done in several steps. The first step is the evaluation of the process with the stored cases. This way can be seen, if the process is safer or unsafer than the alternative processes. The second step is the safety evaluation of specific process systems, subsystems or pieces of equipment. The database contains improvement recommendations to avoid the same accidents happening again. The evaluation of processes can be extended to detailed level. Also the equipment details or safety valves etc. can be checked on this level. 

DATABASES (thermodynamic and diffusion). The calculations require a database for the material systems of interest. For the commercially important materials, databases have been developed by teams of experts critically assessing all experimental phase equilibria and thermodynamic data and, for the complex systems relevant for applications, by extrapolating from binary, ternary and quaternary subsystems. 

To examine this problem more closely it was necessary to develop (1) a model for the nine-component oxide system U02-Zr02-Si02-Ca0-Mg0-Al203-SrO-BaO-La203 to account for the MCCI (Chevalier 1992, Ball et al. 1993) and (2) develop a database for the gas-phase reactions in the oxide subsystem U02-Zr02-Si02-Ca0-Mg0-Al203. The final oxide database included four solution phases and 70 condensed stoichiometric phases. 

Real-time databases and software systems are also important, since they provide the reports and status information that are needed for the smooth operation of the FMS (in particular, its dynamic scheduler and other subsystems such as maintenance should be emphasized here) [4,9-14]. 

Assessment of the information content from the current technical means of collecting data on the state of NSS subsystems and available global databases for their successful allocation in solving the problems of assessing conditions conducive to stress situations in the environment. 

Three flow sheets with consistent assumptions, and using commercially available equipment where possible, were developed. The flow sheets and mass and energy balances were used to generate sized equipment lists. Estimated costs for unit operations are based on industry databases for materials and labour, and on the estimates of technical experts from associated research and development programmes. Installation costs, including labour and field bulk materials, were estimated on a subsystem basis. 

Common approaches for the tailoring of nonmetallic (ceramic) materials properties involve topochemical methods (those where the crystal structure remains largely unaffected) and the preparation of phases in which one or more sublattices are alloyed. In principle, such materials are within the realm of CALPHAD. On the other hand, as has already been stated, extrapolation does not really aid the discovery of new or novel phases, with unique crystal structures. Furthermore, assessed thermochemical data for the vast majority of ceramic systems, particularly transition metal compounds, are presently not available in commercial databases for use with phase diagram software. This does not necessarily preclude the use of the CALPHAD method on these systems However, it does require the user to carry out their own thermodynamic assessments of the (n — 1 )th-order subsystems and to import that data into a database for extrapolation to nth-order systems, which is not a trivial task. 

Step 1 Evaluate the impact of the control scheme and its subsystem on the product quality. This involves the creation of a system inventory or register. The register may be in the form of a validated, controlled, and approved spreadsheet or database. Systems that are deemed to have No Impact on product quality would normally be dealt with by applying Good Engineering Practices. 

Aluminum, boron, carbon, iron, nitrogen, oxygen, phosphorus, sulfur and titanium are the common impurities in the SoG-Si feedstock. Arsenic and antimony are frequently used as doping agents. Transition metals (Co, Cu, Cr, Fe, Mn, Mo, Ni, V, W, and Zr), alkali and alkali-earth impurities (Li, Mg, and Na), as well as Bi, Ga, Ge, In, Pb, Sn, Te, and Zn may appear in the SoG-Si feedstock. A thermochemical database that covers these elements has recently been developed at SINTEF Materials and Chemistry, which has been designed for use within the composition space associated with the SoG-Si materials. All the binary and several critical ternary subsystems have been assessed and calculated results have been validated with the reliable experimental data in the literature. The database can be regarded as the state-of-art equilibrium relations in the Si-based multicomponent system. 

The other subsystems comprising the ISNEM include the Archiving Subsystem with electronic databases for storing all the accumulated data the Process Data Subsystem, comprising warehouse data and applications designed for data processing into a format required by end users and the Data Provision Subsystem, to be used by public administration, public figures and the Central Statistical Office (Nawalaniec, 2003). Data will be provided in the form of reports published on the Internet. 

This hybrid model solves the problems associated with federated data access across the public network, and with internally maintained local database, by combining the two approaches and automating the processes to maintain data currency and accuracy through the content management subsystem and a new software module for dynamic retrieval of additional datasets and automatic updates for revised datasets. 

This database is the national repository for information about airborne pollution in the U.S. AIRS is comprised of four subsystems the Air Quality Subsystem (AQS) the AIRS Facility Subsystem (AFS) and the Geo-Common Subsystem (GCS) and AIRS Area/Mobile Source Subsystem (AMS). 

Table 1 Examples of vitamin and cofactor biosynthesis subsystems in The SEED database... 

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