Hierarchical synthesis

We shall assume that, as a result of such hierarchical synthesis, the elements in systems H and N have at the beginning of the interaction (/ = 0) ... 

Douglas, J. M., A Hierarchical Decision Procedure for Process Synthesis, AIChEJ, 31 353, 1985. 

One approach reUes heavily on heuristics but allows the engineer to interact during the synthesis procedure through a framework of hierarchical decision levels (58,59). 

A hierarchical design procedure for process synthesis can be used in conjunction with a flow-sheeting program to analyze, evaluate, and optimize the options (60). The emphasis is on starting with the simplest possible models that will give answers to a particular question quickly so that the questions to be asked at the next decision level can be formulated. At each stage, it is necessary to ensure that the level of detail in the model is sufficient to give rehable information. 

It is particularly important to study process phenomena under dynamic (rather than static) conditions. Most current analytical techniques are designed to determine the initial and final states of a material or process. Instmments must be designed for the analysis of materials processing in real time, so that the cmcial chemical reactions in materials synthesis and processing can be monitored as they occur. Recent advances in nuclear magnetic resonance and laser probes indicate valuable lines of development for new techniques and comparable instmmentation for the study of interfaces, complex hquids, microstmctures, and hierarchical assemblies of materials. Instmmentation needs for the study of microstmctured materials are discussed in Chapter 9. 

In the first chapter of Volume 2 (hereinafter referred to as 21 1) we presented the general framework of MODEL.LA., a modeling language that can capture the hierarchical and distributed character of processing systems. We will employ all aspects of MODEL.LA. in order to develop a complete and consistent description of plants that will satisfy the modeling needs for the synthesis of operating procedures. 

Fig. 6. Hierarchical description of (a) operational states and (b) operational relationships. (Reprinted from Comp. Chem. Eng., 12, Lakshmanan, R. and Stephanopoulos, G., Synthesis of operating procedures for complete chemical plants. Parts I, II, p. 985, 1003, Copyright 1988, with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK.)...

In this section we will offer several illustrations of the various aspects of nonmonotonic operations planning (discussed in earlier sections) including the following (1) development of hierarchical models for the process and its operations, (2) conversion of constraints to temporal orderings of primitive operations, and (3) synthesis of complete plans. 

Lakshmanan, R., and Stephanopoulos, G Synthesis of operating procedures for complete chemical plants. I. Hierarchical, structured modeling for nonlinear planning. Comput. Chem. Eng. 12, 985 (1988a). 

Brandhuber, D., Torma, V., Raab, C., Peterlik, H., Kulak, A. and Husing, N. (2005) Glycol-modified silanes in the synthesis of mesoscopically organized silica monoliths with hierarchical porosity. Chemistry of Materials, 17, 4262 1271. 

Zhang, Y., et ah, Green and controlled synthesis of Cu20-graphene hierarchical nanohybrids as high-performance anode materials for lithium-ion batteries via an ultrasound assisted approach. Dalton Transactions, 2012. 41(15) p. 4316-4319. 

Fig. 3.10. Schematic representation of processes that may influence hormonal action in a cell. To note is the possibility for feedback in the framework of intercellular communication. A signal released in the target cell can regulate the hormone producing cell by, for example inhibiting the synthesis or secretion of the hormone. Furthermore, the possibility of a hierarchical structure and the mutual influence of different signaling pathways should also be noted.

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