Realization phase

The second half of the glycolytic pathway involves the reactions that convert the metabolic energy in the glucose molecule into ATP. Altogether, four new ATP molecules are produced. If two are considered to offset the two ATPs consumed in phase 1, a net yield of 2 ATPs per glucose is realized. Phase II starts with the oxidation of glyceraldehyde-3-phosphate, a reaction with a large... 

The disadvantage of the two-phase contacting principle is related to the technical expenditure of realizing phase separation throughout the complete reactor passage. Special measures have to be taken to prevent phase inter-mixing. Also, this has to be controlled during the process. Hence inspection windows are essential (for the first prototype they may be eliminated later). 

Phase separation spinning was reported in detail by Zwick [134]. This method allows spinning of fibers at winding speeds of 10-1000 m/min from solutions of polymer contents of 10-25%, with the use of modified melt-spinning equipment. T o realize phase separation, the concentration of the solution has to be chosen so that, on the way from the spinneret to the winder, and at a temperature between that of the spinneret and room temperature, the thin streams of polymer undergo phase separation into a concentrated gel, or pure polymer phase, and a solvent phase. 

The lEC 61508 safety lifecycle prescribes that planning for all maintenance testing and maintenance activities must be accomplished in the realization phase. To a certain extent this work can proceed in parallel with safety instrumented system design. This lifecycle diagram also shows that operation and maintenance responsibilities focus on periodic testing and inspection as well as management of modifications, retrofits, and eventual decommissioning. 

Figure 1-8. Detailed Realization Phase of the Safety Lifecycle...

During the concept and realization phase, requirements are derived from the collected use-cases and business as well as administration services are formulated. A functional architecture of the SE environment is to be defined, in which supporting services are considered. The methods of the different disciplines involved are to be aligned in order to take a higher benefit of SE. Thus, the concept considers not only the necessary software, but also the methodological way of working. 

Depending on the SE architecture that has been defined, adjustment of the IT architecture might be necessary, e.g. additional leased lines could be necessary to guarantee some business services, especially when it comes to providing the extended enterprise with internal workflows. Further tasks after the concept and realization phase are the SE implementation and the test and rollout of the solution. 

Figure 11 - Application software safety life cycle (in realization phase)...

E/E/PE system safety life cycle realization phase. 

Software specification (Clause 7.2) As seen from the previous table, the first part in realization phase of software starts with the requirements of software specification. Specification, including terminologies, shall be clear, precise, verifiable, testable, maintainable, and feasible, and detailed enough to allow... 

Software safety life cycle in process industries. (A) Software in realization phase (B) safety life cycle relation between software and safety instrumented system. 

The position of FAT is between the design stage and the installation stage. So, with discussions on design phase now complete, we next move on to the installation and commissioning in the life cycle realization phase. 

Note the stages of the lEC model. The first 4 phases are concerned with design, then the realization phase is reached. This term describes in very general terms the job of actually building the safety system and implementing any software that it contains. 

Large sections of lEC 61508 are concerned with the details of the realization phase and there are whole life cycle models for the activities contained within this stage. Some sections of the lEC standard are dedicated to these specialized tasks. Bear in mind that some of the deeper parts of this standard will be applicable to manufacturers of certified safety PLCs and their associated software packages. A process engineering project would not be expected to dive into such depths. 

The SIS safety requirements specification should be developed in association with the non-SIS protection layers. The lEC 61508 standard calls for the overall safety requirement to be defined first in phase 4 followed by an allocation phase 5, which defines the sharing of protection duties across the layers of protection. The final SRS for the safety-instrumented system is then part of the detail design activities for the SIS known in lEC terms as the realization phase (phase 9). This procedure can be rather confusing at first but it appears to be designed to ensure that the basics of the SRS are in place and verified before the design team goes too far with the technical specifications for the SIS. 

Life cycle model for the realization phase based on Figure 2 of lEC 615008part 2... 

For further guidance on the workflow needed for an SIS project there is a useful example set out in part 6 of lEC 61508. Annex A of part 6 is an informative section on the application of parts 2 and 3 of the standard. Section A2 in particular describes the functional steps in the application of lEC 61508-2. Documents us or created in the realization phase will include ... 

A general method to realize phase-matching, is to use the natural birefringence in certain anisotropic crystals to compensate for the refractive index dispersions between the fundamental and second-harmonic wavelengths and realize ni = nL [167-169]. There are two types of collinear... 

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