Online analytical processing

Front-ends provide information to the end-user for decision making. They usually comprise query and reporting tools and may be supported by data mining and online analytical processing (OFAP) tools. 

Content management via a data warehouse is based on an online analytical processing (OLAP) data structure, as opposed to the operationally tuned OLTP data structure. In terms of data access characteristics, OLAP operations... 

The traditional approach for data repositories for OLAP (online analytical processing) system or DSS (decision support system) is to create a central data warehouse to aggregate a superset of data relevant to OLAP or DSS. The data... 

OLAP (online analytical processing) The sophisticated manipulation of data for analytic purposes, often using data organized into the cube structure. 

Automatization of all stages of the analytical process is a trend that can be discerned in the development of modern analytical methods for chemical manufacture, to various extents depending on reliability and cost-benefit considerations. Among the elements of reliability one counts conformity of the accuracy and precision of the method to the specifications of the manufacturing process, stability of the analytical system and closeness to real-time analysis. The latter is a requirement for feedback into automatic process-control systems. Since the investment in equipment for automatic online analysis may be high, this is frequently replaced by monitoring a property that is easy and inexpensive to measure and correlating that property with the analyte of interest. Such compromise is usually accompanied by a collection of samples that are sent to the analytical laboratory for determination, possibly at a lower cost. 

Manufacturing information systems for real-time process control in the lab and for efficient statistical process control, as well as the right number of lab trials, limits information losses between the plant and the labs. Parallel synthesis, such as units with online analytics in the lab, and the use of new technologies such as Micro Reaction Technology developed by Clariant and a few other companies for application in production mean a step change in reproducibility. 

Both plant concepts, [R 10] and [R 11], can be equipped with different types of online analytics, e.g. pH value, conductivity, UV, IR, and different process control units. Incorporation of additional reactor device allows one to perform even complex chemical reactions, including gas/liquid reactions. The pressure is limited to 8 bar, in special cases up to 30 bar, and the maximum temperature is 200 °C. 

A modern-day petroleum refinery is a complex chemical operation that involves numerous separations and chemical processing steps. Today virtually all the chemical analysis equipment found in the research laboratory is also used in the refinery or an online basis is often coupled to a control circuit to monitor product quality and make the necessary immediate adjustment in process conditions required to meet product specifications. While the online gas chromatograph is the most widely used instrument, infrared spectrometers, mass spectrometers, pH indicators, new infrared spectrometers with chemometric capability and moisture analysis based in solid-state conductors are not found in every refinery in the country. Until the 1970s, samples of most process streams in the refinery were taken at periodic intervals during the day and adjustments were made after the research was received from the refinery s analytical lab. This process was followed by the installation of online analysis equipment that sounded alarms, and the equipment operators took appropriate action. Today most operations are on computer control and the information received from online analytical equipment is processed almost continuously and controls make the required changes. An alarm may still sound and the equipment operator still responds, but usually the problem has already been corrected. 

Both can be done very effectively by using methods of online analytics combined with an appropriate automatic controller. Useful methods for online analysis of enzymatic processes are... 

The term online implies that analytical methods gain information directly from the process. This is in contrast to offline analytics, where a sample is taken from the process and transferred to a central analytical laboratory with sophisticated instrumentation. Formally, online analytical techniques can be further classified into atline, online, inline, and noninvasive techniques [6, 7]. 

Static pressurized liquid extraction, as implemented in commercial equipment, is basically discrete in nature, and so it is rarely coupled to other operations of the analytical process. In fact, only in a few reported applications is the static mode coupled online to other operations such as chromatographic separation, preconcentration, and detection. In any case, custom extractors are used as the compact design of the commercial models precludes their adaptation. 

Separation steps are quite often included in the analytical process in order to increase the selectivity and sensitivity of the overall determinations by removing undesirable interferents and preconcentrating the analyte(s), respectively. By appropriately coupling the separation technique and an FI manifold, separation/preconcentration processes can be performed automatically. The major separation techniques that are coupled online with FI manifolds are discussed, and the basic units required in each case are described. 

Multidimensional chromatography is one of the best options to prevent unwanted coelutions of analytes with other matrix components present in a variety of complex samples, and also to incorporate automated online sample preparation in the analytical process. Nowadays, well-developed methodologies already exist using multidimensional modes as LC-LC or SPE-LC in combination with spectroscopic or electrochemical detection for the selective and sensitive determination of many analytes, mainly in the biomedical, pharmaceutical, environmental, and food fields. 

Membrane separation involving liquid membranes is an attractive alternative to the extraction techniques outlined above. Eike SPE and SPME, separation based on liquid membranes requires small amounts of organic solvents, if any, while at the same time it offers the high selectivity, flexibility, and enrichment factors of EEE and SME. Eiquid membranes are suitable for online analytical separation, since the extraction and back-extraction are integrated into a single step, unlike the sequential arrangement of these processes when other extraction techniques are used. 

The instrumentation used in at-line and online analysis differs from laboratory instrumentation in that it is rugged and dedicated to a particular task, i.e., continually monitoring the same process stream, whereas laboratory-based analytical instruments are usually used to determine many analytes. Process analyzers are usually installed in safe analyzer houses that are kept at a constant temperature and pressure and have air continually passed through them to... 

Online analysis Online sample processing techniques such as flow injection provide advantages such as reliability, sample economy, ease of automation, measurement standardization, high speed, optional sample dilution, and the ability to derivatize the analyte so as to suit the analyzer/detector. These procedures facilitate the online monitoring of fermentation substrate materials, respiratory gases, and biomass. The modifications to flow injection analysis for accurate discontinuous flow operation include sequential injection analysis and bead injection spectroscopy. The most recent invention in online techniques is the introduction of the Lab-on-a-Valve, which opens the way to development of a novel type of microflow analytical system monitored by UV-visible spectrophotometry using fiber optics. This system is an ideal tool for fermentation monitoring. 

---