Advanced control approach

J. Harmand and J.P. Steyer. Comparison of several advanced control approaches for anaerobic digestion processes Towards a new paradigm. In IWA Conf. Instr., Contr., and Automat. (ICA), pages 647-654, Malm5, Sweden, June 2001. 

Figure 5.3 General structure of the algorithm for the advanced control approach. Adapted from Hristu-Varsakelis D, Shao C. A bio-inspired pursuit strategy for optimal control with partially constrained final state. Automatica 2007 43(7) 1265—1273.

Regulatory Control For most batch processes, the discrete logic reqmrements overshadow the continuous control requirements. For many batch processes, the continuous control can be provided by simple loops for flow, pressure, level, and temperature. However, very sophisticated advanced control techniques are occasionally apphed. As temperature control is especially critical in reactors, the simple feedback approach is replaced by model-based strategies that rival if not exceed the sophistication of advanced control loops in continuous plants. 

Since perfect knowledge of the model is rarely a reasonable assumption, soft computing methods, integrating quantitative and qualitative modeling information, have been developed to improve the performance of observer-based schemes for uncertain systems [36], Major contributions to observer-based approaches can be found in [39, 56] as well, where fault isolation is achieved via a bank of observers, while identification is based on the adoption of online universal interpolators (e.g., ANNs whose weights are updated on line). As for the use of observers in the presence of advanced control techniques, such as MPC or FLC, in [44] an unknown input observer is adopted in conjunction with an MPC scheme. 

In a well-engineered system, measurement noise is unlikely to affect the performance of a PI controller significantly (Section V.A.2), but it may limit the use of derivative control action and will certainly limit the performance of advanced control schemes that attempt to approach ideal control (Section V.A.5). Our approach to PID control has been to optimize PI controllers and leave the possible benefit of derivative action to the commissioning engineers. 

Advanced Control applications are part of the broader context of Industrial Automation, a multidisciplinary activity which has evolved for more than twenty years in our refineries, so it seems fit to start with a brief history of Industrial Automation in the Downstream area of the company. This is dealt with in section 2. Section 3 explores the details of the monitoring process and the plans to develop a more comprehensive approach by adding measures of... 

The host computer is a mainframe that is used for data storage, process optimization calculations, and applying advanced process control approaches. Attached to the host computer is the data storage unit (usually a magnetic tape system) where archived data are stored. 

Future work will concern more sophisticated polymer networks capable of switching complex sequences of developmental steps as required for the (re-) generation of specialised tissues and organs. For that aim, the structural and biomolecular complexity of hydrogel-based materials has to be increased and the characteristics of these future materials have to be temporally and spatially controlled. This will require advanced synthetic approaches which, in turn, have to be underpinned by powerful analytical strategies. Accordingly, the future research... 

This project is based on leveraging developments at GTI in the stationary PEM fuel cell and compressed natural gas vehicle market sectors. GTI has been developing high-efficiency steam methane reformers for stationary fuel cells, including design approaches to achieve compact size, reduced cost, and simplified control and operation. Modification of this reformer—as a hydrogen generator with advanced controls—will comprise a core element of this system. 

Recent advances in the growth of organic molecular layers suggest that beyond this rather simple kinetically controlled approach a molecular assembly due to directed forces between the deposited entities, which rather creates equilibrium structures, is feasible. This will open the way to an even bigger number of potential surface templates. 

An advanced nanopatteming approach of functional materials that do not independently self-assemble is to employ stmcture-directing agents, such as copolymers with hydrophilic and hydrophobic blocks [12]. The fact that precursors to functional materials or nanoparticles preferentially swell one of the copolymer blocks is used for co-self-assembly which is driven by the polymer s phase separation behavior. However, increasing the number of components also multiplies the complexity of the assembling system and thereby the control of stmcture formation. Hence, this nanopattering approach was only demonstrated for a few functional materials [13]. 

Although advanced control and optimization methodologies have been extensively discussed in the scientific literature throughout the last three decades (Cutler and Ramaker, 1980 Morari and Lee, 1999 Manenti, 2011), conventional control systems are still the most commonly used approaches in the process industry. In this framework, the integral part of each traditional control loop corrupts the Jacobian structure by introducing unstructured elements. These considerations make this example and, more specifically, the development of better performing, tailored numerical solvers for partially structured systems highly relevant. 

The most advanced analytical approaches are incorporated into doping controls. Today, MS and particularly GC-MS, is so far considered the less likely technique to be challenged in Court. Noticeably, LC-MS has significantly added to the extension of the panel of compounds already detected by GC-MS including large, polai and/or thermolabile substances. 

---