Sequencer, programmable

A prototype apparatus (Fig. 4) developed by Chalkley and Renshaw, utilizing the CRC thimble will automatically filter the contents of 100 tubes in pairs. The basis of the apparatus is a box that contains tubing and a sequence programmer and holds in place electrical and mechanical com-... 

Discrete logic. Sequence logic can be implemented via ladder logic, and this approach is common when sequence logic is implemented in programmable logic controllers (PLCs). 

Bums and Hazzan demonstrated tlie use of event tree and fault tree analysis in tlie study of a potential accident sequence leading to a toxic vapor release at an industrial chemical process plant. The initiator of tlie accident sequence studied is event P, the failure of a plant programmable automatic controller. Tliis event, in conjunction willi the success or failure of a process water system (a glycol cooling system) mid an operator-manual shutdown of tlie distillation system produced minor, moderate, or major release of toxic material as indicated in Fig. 21.4.1. The symbols W, G, O represent tlie events listed ... 

In Section 21.4 tlie effects of the release of toxic vapors were considered in connection witli an accident sequence initiated by the failure of a plant programmable automatic controller. In tliis study, event tree analysis and fault tree analysis led to identification of tlie glycol cooling system circulation pumps as components meriting high priority for inspection. 

Two main approaches to combinatorial chemistry are used—parallel synthesis and split synthesis. In parallel synthesis, each compound is prepared independently. Typically, a reactant is first linked to the surface of polymer beads, which are then placed into small wells on a 96-well glass plate. Programmable robotic instruments add different sequences of building blocks to tfie different wells, thereby making 96 different products. When the reaction sequences are complete, the polymer beads are washed and their products are released. 

Programmable logic controllers are used for the control and interlocking of processes where a sequence of operating steps has to be carried out such as, in batch processes, and in the start-up and shut down of continuous processes. 

First, it is useful to understand what we mean by 1-D and 2-D experiments. If you consider a normal proton spectrum, it is plotted in two dimensions (chemical shift on the x axis and intensity on the y), so why is it called 1-D In fact, when NMR started, it wasn t because there was no need to distinguish it from what we now call 2-D. The dimensions that we are talking about are the number of frequency dimensions that the data set possesses. To try to understand we need to explain the basics of the pulse programme. If we take a simple example (e.g., 1-D proton) we can represent the pulse sequence in Figure 8.1. 

Rule 3 Exclude programmes according to the extended dominance rule, that is, if some cost-benefit ratios are lower than the previous ones in the sequence of increasing effectiveness, those with less effectiveness must be excluded. 

We use the term programmable to describe the rational (and ideally, computer-aided and automated) approach to polysaccharide synthesis.20 To reduce the synthesis of complex carbohydrates to routine, we envision a four-step protocol (1) the sequence of interest is keyed into a computer, (2) the computer selects appropriate reagent combinations, (3) a laboratory worker (human or robotic) prepares the reagent... 

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