Serializing operations

Detectors are not limited to solo use they can be hooked in series to get more information from the same sample. In a serial operation, be sure that the refractive index detector or electrochemical detector is the last in the line. Their flow cells are more fragile than UV and fluorescence cells and won t take the increased back-pressure. Keep the tubing diameter fine and as short as possible to avoid band spreading. You must correct for connecting tubing volume (time) delay in comparing chromatograms from the two detectors. 

The Cu/Cr system was also investigated in the serial operation mode. Owing to initial deactivation of the catalyst at the first 10-12 hours, the measurements were carried out once a steady state has been reached. It could be demonstrated that a subsequent increase in the residence time by introducing one to eight catalyst platelets always led to the same relative increase in conversion and hydrogen yield (100%), because no other products were detected. For all experiments the maximum... 

A relevant restriction to be fulfilled for operating pipeUnes is the flow balance. I.e., the input flow equals the output flow implying constant physical conditions (such as pressure) for all pipeline segments. For instance, assume a serially operated multi-access pipehne where N is the set of access points consisting of destination points and M " feeding locations such that = 0 and JM " = N. The flow rate p is measured... 

The flrst point is a reasonable assumption provided there is a disjunctive categorization of locations into material (net) providers and (net) consumers such that there is one unique flow direction within the pipeline, i.e. Xj > 0 or X/ < 0 for all locations j. I.e. if the pipehne is serially operated, the total safety stock has to be distributed among the provider locations. Another situation occurs for cyclic pipehnes. Here, the material flow is unidirectional, but each location can act as consumer or provider as long as the total flow is balanced. The safety stock can be distributed among all participants along the pipehne as long as all participants can feed surplus material from stock to starving partners. 

The following example exercises the aforementioned procedure to derive safety stock levels for a serially operated pipeline system with two provider locations and two consumer locations... 

Naturally, the quality of these decomposition approaches is considerably affected by the neglected interdependency of the decomposed decisions. Therefore, monolithic, time and volume-continuous MILP formulations are proposed recently to integrate these decisions. These models are straight-forward adaptations of one-to-many approaches. The basic setting is adapted from the one-to-many case (see the previous paragraph), i.e. a serially operated main pipeline is assumed with a refinery at its head and depots along this pipeline. One key alteration is that depots now can receive and inject batches in the pipeline. Most other assumptions are inherited from the one-to-many systems. In particular, the product flow is stiU unidirectional and only one location at a time can inject a batch in the pipeline. ... 

If the reaction is to be performed in a continuous setting, two separate sets of equipment are required and must be operated simultaneously. Compositions are then obtained by mixing the necessary streams belonging to each structure in the appropriate proportions. By comparison, if it is desired to perform the same task under batch conditions, an identical outcome may be achieved by two serial operations together with intermediate storage of material used in mixing processes. Hence, it may turn out that a single set of reactive equipment is sufficient to achieve the same result. 

An example of serial operation is determination of LCST, for a polymer during synthesis by passing the diluted stream through a series of scattering detectors, each at a different temperature. A-isopropyl acrylamide (NIPAM) and its copolymers are a well-studied example of polymers with LCST behavior [112-116]. Below the LCST NIPAM is hydrophilic, in the form of a random coil stabilized with many hydrogen bonds. When the LCST is reached, the... 

Resource conflict resolution. A resource binding implies a cotain configuration of hardware sharing. In general, resource conflicts can arise when a resource is accessed simultaneously by multiple op tions. These conflicts can be resolved by serializing operations bound to the same resource that can otherwise execute in parallel. Timing constraints must still be satisfied after conflict resolution. 

Two operations opl and op2 are disjoint in time if one of the two following conditions holds (1) opl is serialized with respect to op2 in the graph, such that opl can execute only if opl has completed execution or vice versa, and (2) opl and opl each belong to different mutually exclusive branches of a conditional. The two cases are illustrated in Figure 7.1. Since the conditional branching structure cannot be arbitrarily altered without changing the external behavior of the model, we resolve resource conflicts by serializing operations. 

Instead of calculating the Hamiltonian using equation (5.3), it is possible to write down H directly for a serially operating computer. 

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