Objective trees

Objective Tree clarify design objectives and sub-objectives, and their relationships... 

Figure 12.8-2. Objective tree for indoor air quality control appliance.

Each one of these tables will have a data mapper object. There might be other tables such as name table and distribution table, and they can be handled in the same way. These data mapper objects are used together to build the entire object tree that was described in Chapter 12 and to insert, update, and delete a record in the database. 

The methodology that was selected for this taxonomy of pretreatment processes is the objectives-tree method developed by Swager (7) Lipinsky (8), Janstch (9), and others (10) for presentation of alternatives in a systematic structure. 

Fire may be defined as the interaction between fuel, energy, and environment. The type and magnitude of any fire that either develops into a destructive force or into a useful tool depends on the supply of fuel. Mass fires in natural environments, urban surroundings, farmland, and many industrial and miscellaneous installations mainly involve natural fuels that are cellulosic substances, such as wooden structures and objects, trees, dried vegetation, textiles, furniture, boards, paper, and paper products. 

A report including the brainstorming exercise, objective tree, function mean tree, morphological chart, decision selection matrix as well as any other brainstorming and decision-making exercises. 

We now show highlights from one student team as they solved this problem and take their work as cpieues to describe the learning process. Students are first taught to critically read client problem statements and expand upon them through client interview and several conceptual desigu tools such as objective trees , pair-wise comparison charts , and more. The objective tree created by Team 1 is shown in Fig. 4.6. 

Objective trees help students brainstorm on specific goals for a design that are gleaned from the broad goals present in the chent problem statement. Students then create a pair-wise comparison chart to determine, by team consensus, what the priorities are associated with each objective, as is shown by Team 1 in Table 4.4. Summed ranks in the right column give an estimate of importance. 

Fig. 4.6 A flowchart representation of the objective tree as presented by Team 1...

Clearly present the objective tree similar to Figs. 3.1 and 3.2 (Dym and Little 2003) 10... 

There are two basic types of analytical tree. The positive tree, or objective tree, which is developed to ensure that a system works properly, and the negative tree, or fault tree, which is generally used for troubleshooting and to investigate system failures (Fig. 10-2). 

Positive or objective trees are extremely useful planning tools. In the early stages of a project, they can be used to outline project requirements and list alternatives. As decisions are made, they evolve into graphic checklists and also make excellent status charts and project description documents. 

A fault tree is simply a mirror image of the positive or objective tree. The objective tree is converted to a fault tree by changing all the and gates to or... 

POSITIVE (OBJECTIVE) TREES TO MAKE SYSTEMS WORK RIGHT... 

For easier and more user friendly applicability, the method that is reviewed in this publication, including the overview of all challenges, mechanisms and provisions for all levels of defence, is illustrated in the form of objective trees . ... 

Section 2 addresses the strategy of defence in depth and the importance of fulfilling the safety functions (SFs) to achieve the objectives for the different levels of defence. Section 3 provides a detailed description of the approach for making an inventory of the defence in depth capabilities of a plant. Section 4 discusses the applications of the approach and how to use the approach for assessing defence in depth. Section 5 presents conclusions. A discussion of the SFs is presented in Appendix I. In Appendix II, the objective trees graphically represent how, for each relevant safety principle , the safety objectives of the different levels of defence can be achieved by establishing defence in depth provisions at different stages of the lifetime of the plant. A test application of the approach is summarized in Appendix III. Definitions are provided at the end of the book. 

The framework described above may be graphically depicted in terms of an objective tree , as shown in Fig. 2. At the top of the tree there is the level of defence in depth that is of interest, followed by the objectives to be achieved, including the barriers to be protected against release of radioactive material. Below this, there is a list of FSFs or derived SFs which need to be maintained to achieve both the objectives and the protection of the barriers of the level of defence under consideration. For instance, for Level 2 the objective is to control abnormal operation and to detect failures, as well as to ensure the... 

There might be an impact on the performance of FSFs/SFs by challenges which are placed on a lower level of the objective tree. On the next lower level of the tree there are several mechanisms listed that can give rise to the challenges. Under each of the mechanisms, there is a hst of possible provisions that should be implemented in order to prevent the mechanisms from occurring and to prevent challenges to the SFs from arising. 

The objective trees are presented in Appendix II for all the levels of defence based on the approach described. The trees themselves are self-explanatory, i.e. no additional text is provided to explain the challenges, mechanisms and provisions. Further guidance can be found in Refs [2,4,5]. 

The following remarks can be made on the formulation of provisions in the objective trees ... 

In total 68 different objective trees have been developed for 53 specific safety principles assigned to the five levels of defence ... 

Users of the method presented in this pubhcation are expected to review and compare provisions for defence in depth identified in the objective trees with the existing defence in depth capabihties of their plant. The objective trees provide the rationale for the bottom up method, starting with the screening of individual provisions. Users should evaluate for each provision the level of its implementation. If the implementation of provisions is satisfactory, then the relevant mechanism can be considered as having been prevented from occurring. Deviations should be discussed and either justified by compensatory features specific to the plant or reconsidered for further strengthening of the defence in depth of the plant. 

Feedback is welcome from users to the developers of the method for improving it. In this connection, the appropriateness of the mechanisms and challenges set in the objective trees needs to be verified. Comments on the text in the boxes of the objective trees are also welcome in order to address more precisely the relevant safety aspects. Special attention needs to be given to the objective trees of those safety principles that are applicable to more than one level of defence and to the need to make further appropriate distinctions between provisions belonging to different levels of defence. 

The following set of SFs have been taken directly from Ref. [4] as appropriate to develop the objective trees in Appendix II ... 

To keep the size of some of the objective trees within reasonable limits, their presentations for different SFs at the same level of defence are given on more than one page, e.g. SP (200) for Levels of defence 3 and 4, which are presented separately for SF (2) and SF (3) in Figs 33 and 34, respectively. 

FIG. 11. Objective tree for Level 1 of defence in depth (PIE, postulated initiating event). Safety principle (136) external factors affecting the plant. 

FIG. 14. Objective tree for Levels 3 and 4 of defence in depth (MCR, main control room). Safety principle (138) radiological impact on the public and the local environment. 

FIG. 15. Objective tree for Levels 1-4 of defence in depth (RCS, reactor coolant system LOOP, loss of off-site power UHS, ultimate heatsink). Safety principle (142) ultimate heatsink provisions. 

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