Operation sequence

2-3 Control System. The operation of the reactor unloading mechanism is electrohydraulically controlled. The power that operates the mechanism is hydraulic. The flows in the hydraulic system are governed by soleiioid-operated valves. The valve solenoids are operated by push-button switches in. the various electrical control circuits. These circuits are interlocked by pressure switches, limit switches, and relays to ensure proper sequence of 

A pair of push buttons is provided at the contrC l board for each of the following operations 

Opening or closing of the seal at the disch ceiver junction. 

Baising or lowering of the eject pistcn in the receiver cylinder. 

The position of the eject piston in the receiver cylinder is indicated by a dial mounted on the control board. Indicator ligUts on.the control board provide information about the other operations. 

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Fig. 4. Operating sequence for a two-lobed rotary gas flow meter where the shaded area represents the flowing fluid.

Fig. 5. Operating sequence for a rotating-vane positive-displacement meter.

The performance of a centrifugal compressor (discharge to suction-pressure ratio vs. the flow rate) for different speeds is shown in Fig. 11-87. Lines of constant efficiencies show the maximum efficiency. Unstable operation sequence, called surging, occurs when compressors fails to operate in the range left of the surge envelope. It is characterized by noise and wide fluctuations of load on the compressor and the motor. The period of the cycle is usually 2 to 5 s, depending upon the size of the installation. 

A filter press with membrane plates has the following operational sequence ... 

Operational sequence diagrams are flcw-charting techniques that represent any sequence of control movements and information collection activities that are executed in order to perform a task. Various activities in the diagram are represented with a symbolic notation, supported where necessary by a text description. For the majority of simple applications, OSDs assume a linear flow drawn from top to bottom with a limited degree of branching and looping. The symbols used are usually tailored to fit the type of task being studied and its level of analysis. 

FIGURE 4.7. Temporal Operational Sequence Diagram in a Slitting Coated Fabric Operation (from Barnes, 1980). 

FIGURE 4.8. Partitioned Operational Sequence Diagram for Loading a Recipe to a Computer Controlled Reactor (adapted from Kir-wan and Ainsworth, 1993). 

In spatial OSDs the flow of events and symbols is overlaid on a map of all items of equipment with which the operator interacts during the task. The map itself does not have to be very accurate, provided that the general geographical relationships among items of equipment are shown. The spatial OSD thus provides a graphical description of the perceptual-motor load a particular task imposes on the performance of the worker. For multiperson tasks, the operational sequences for several workers can be coded in different colors and superimposed onto the same equipment map. This can generate useful information for the distribution of tasks to different members of the operating team. 

Operational sequence diagrams are very useful to show temporal, spatial, and even conceptual relationships among operations that are difficult to show by textual or tabular representations. 

Operational sequence diagrams can become cluttered and confusing when used for complex or highly conditional tasks. It is particularly important that the analyst is working to the level of detail that is most appropriate. 

Operational sequence diagrams cannot represent highly cognitive tasks because it is difficult to assign cognitive components to discrete symbols. 

FIGURE 4.8. Partitioned Operational Sequence Diagram for Loading a... 

Splicing. Splicing wire rope requires considerable skill, and the instructions for splicing wire rope will be found in the catalogues of most of the wire-rope manufacturers, where the operation sequence is carefully described, and many clear illustrations are presented. These illustrations give, in fact, most of the information needed. 

A burner safety control system required to ensure proper operating sequences are employed. 

Figure 1, Forcing functions for monomer (fu) and initiator (fi) feeds (a) sinusoidal (b) square-wave (c) reception vessel valve operating sequences which are synchronized with the feed policies (see Figure 2 for the location of the valves...

The solution of Problem-1 requires extensive search over the set of potential sequences of operations. Prior work has tried either to identify all feasible operating sequences through explicit search techniques, or locate the optimum sequence (for single-objective problems) through the implicit enumeration of plans. The former have been used primarily to solve planning problems with Boolean or integer variables, whereas the latter have applied to problems with integer and continuous decisions. 

Figure 3.7 The crystal structure of DtxR, a 226-residue three-domain dimeric protein, is shown. The protein, activated by cobalt (designated 1 and 2), is bound to a 21-bp DNA duplex based on the consensus operator sequence. Two DtxR dimers surround the DNA duplex, which is distorted compared to canonical B-DNA. Only domain 1, involved in DNA-binding, and domain 2, involved in dimer formation, are shown. The helices of the DNA-binding domain are indicated by HI, H2, and H3. H3 binds to the major groove of the DNA. From Pohl et al., 1999, by permission of Academic Press. 

P = constitutive promoter, tetR = TETrepressor gene,TETR = TET repressor protein, tetO = TET operator sequence, = tetracycline, ere/CRE = Cre recombinase gene/protein, PLEA = late embryogenesis abundant promoter, RIP = gene for ribosome inactivating protein, shaded blocks are loxP sites in orientation shown by solid triangle. After [48]... 

Fig. 5.42 Power Activation Mode -operation sequence for Ga203-natural gas sensors to avoid false alarm in the presence of ethanol and other interfering air components [20], (With kind permission of D. Kohl, D. Skiera and M. Lam-mer, Institute of Applied Physics, University of Giessen, Germany)...

The operation cycle is a stepwise process. The essential steps are filling the vessel, filtration (service), back-pulse (cleaning), cake settling, and sludge discharge. In practice, the steps will vary in length from application to application, but all working operation sequences include these basic steps, which will be addressed in order. 

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