Subtask 2 Operation

A PSA consists of many tasks and subtasks some tasks are performed in parallel others are in series. The experience of personnel, availability of data, computer programs, and manpower determine the PSA schedule. Other considerations are the age of the plant, its operational status, availability of documentation, peculiarities of the design, and the availability of the analyses of similar fiiants,... 

This ranking exercise can be assigned to one or two team members as a subtask. Consider selecting a teammate with experience in facility operations to compile the necessary data and one with process safety and computer experience to run the models. The resulting report can then be shared with the full team and included in the plan you submit to your management. 

Figure 5.6 shows an extract from the HTA of the chlorine tanker filling operation which will be used as an example. The first level (numbered 1,2,3, etc.) indicates the tasks that have to be carried out to achieve the overall objective. These tasks are then broken down to a further level of detail as required. As well as illustrating the hierarchical nature of the analysis. Figure 5.6 shows that plans, such as those associated with operation 3.2, can be quite complex. The term operation is used to indicate a task, subtask, or task step, depending on the level of detail of the analysis. 

The first stage of the operation error analysis is to determine if any of the error categories in Figure 5.7 apply to the task, subtask, or task step being analyzed. For example, at the level of individual task steps, operations would... 

The HTA is shown in Figure 7.11. The overall job is broken down into six subtasks which must be carried out in sequence. The analyst can specify these subtasks as he or she wishes. For instance, "starting the metered pump" and "complete pumping" can be assigned to the same group if this is convenient. The job analysis has been taken to the level of operations where the worker interfaces with the system. This is necessary in order for the PHEA to address possible errors associated with the job. 

In compliance with EURACHEM/CITAC Guide 2 [72] polymer/additive analysis can be considered as a collection of discrete subtasks (Figure 1.3), each consisting of a number of unit processes, themselves composed of modules containing routine unit operations. The unit processes are characterised as being separated by natural dividing lines at which work can be interrupted and the test portion can be stored without detriment before the next step. 

When we design a procedure that refines an operation spec, we can focus on the receiving object and devolve subtasks to other objects we send messages to. If we change the design, we are changing this one object. 

As was discussed in Chapter 2 Rasmussen has provided the basic model of human error based on three levels of behaviour skill-, rule- and knowledge-based (S-B, R-B, K-B). This SRK model has been operationalised to describe operator errors in process control tasks by combining it with characteristic task elements, which as a whole cover the entire spectrum of operator subtasks. 

The 3D simulation expert, who also plays the manager role for this small subprocess, starts the task for 3D simulation. The corresponding state change is propagated immediately via the communication server. Thus, the client keeps informed about the operations performed by the contractor (and vice versa). Subsequently, the 3D simulation expert refines the simulation task into a sequence of subtasks for analyzing the results of ID simulation, generating... 

The specific goal of the Clean Fuels PEPS project is to design a system that, when installed and operational, will demonstrate that the PEPS Gasification process is efficient, environmentally compliant, and cost competitive for alternative fuel production with specific emphasis on using petcoke as a feedstock. The initial phase of the project was divided into three subtasks ... 

The results in Table 8 show a slight difference in the total production time, which seems to contradict the hypothesis that the integrated scenario wiU benefit from a reduction of the cycle time. However, it must be noted that the number of subtasks required by the local scenario for achieving a comparable total production time is double that required by the integrated scenario. This situation is the result of no constraint being imposed on the maximum number of subtasks for each task in each scenario (infinite division of tasks). In particular for operation B, the number of subtasks in which each task is divided is nine, which can be considered excessive given the total number of four tasks in the operation. 

For evaluating the comparative performance of the integrated and local scenarios, the local scenario for each operation was chosen according to the final number of subtasks in the integrated... 

Process description a breakdown of a process into subtasks or steps, expressing the requirements for each step and its relationship to other steps in the recipe. Every process description has an associated active resource that is responsible for planning and executing the process described. Process descriptions come in many forms NC programs, routings, operation sheets, recipes, etc. 

At each work-place, the manual assembly subtasks can be studied by operation method studies. Normally, there is a distinction between motion study and time study. In these studies, the layout of the work-place is analyzed and the placement of the components to assemble is described. The motion study concentrates on recording and analyzing the motion elements types and magnitude of motions. The optimization goal is minimizing movement. The time study is used to determine the normal (average) time consumption for optimized movements (Riggs 1987). 

For this reason, it is important to decide which approach to take for a particular holon. Figure 2 shows an overall outline of our revised architecture for the production operations activity model in level 3 of ISA-95, considering each high-level activity in ISA-95 as a holon formed by its subtasks and the people and machines involved. In general, we can summarize the decision process into the following questions ... 

We have described an approach for processor synthesis. We divide the problem into three interdependent subtasks, namely, operation scheduling, data path binding and controller synthesis. The first subtask includes both time-constrained and resource-... 

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