Trade studies

The costs associated with lighting tend to be the major economic factor in trade studies of plant-based life support approaches (Diysdale et al., 2003). For example, highly productive plant systems for life support might require about 200 W ( 1000p,mol m s )... 

Update baseline reformer and fuel cell cost estimates to reflect advances in technology and additional manufacturing and design improvements. Conduct a series of in-depth trade studies on selected issues to assess pathways to lower cost systems. 

Conducted a manufacturing trade study of alternative means and materials for fabricating the CH2-ISS outer protective shell... 

In the development of the computer program for the propellant tank pressurization-system analysis outlined in this paper, some theoretical rigor was sacrificed for application flexibility. This flexibility enables the design engineer to run system-trade studies which account for effects of ... 

Integrating Safety into Architecture Selection and System Trade Studies... 

Alternatives to the standard risk matrix are possible, but they tend to be application specific and so must be constructed for each new system. For many systems, the use of severity alone is often adequate to categorize the hazards in trade studies. Two examples of other alternatives are presented here, one created for augmented air traffic control technology and the other created and used in the early architectural trade study of NASA s Project Constellation, the program to return to the moon and later go on to Mars. The reader is encouraged to come up with their own... 

Dulac, Nicolas. Incorporating safety risk in early system architecture trade studies. AIAA Journal of... 

Define potential candidate solutions and conduct trade studies... 

These and many other broad system issues will be the topics of the trade studies necessary to identify the preferred system. It is clear that manufacturing, delivery, and installation will have an important impact on size selection of the reactor system the size may vary depending on the system technology. 

This paper updates the design status of the GT-MHR with emphasis on the PCS. Section 2 reports on the trade study that addressed the question of whether the generator should be submerged in helium within the power conversion vessel or be external to the vessel necessitating a... 

The enterprise selects the general approach, resources, and procedures for performing trade-studies based upon the trade-study definition, its level of importance, and availability of tools, fadhties, special equipment, and related resources. The enterprise also lists the set of selection criteria, which includes factors that characterize what makes a specific alternative desirable, such as cost, schedule, performance and risk life cycle quality factors reuse and size, weight, and power consumption. Adverse quahties as well as favorable qualities should be included as criteria. 

The enterprise establishes metrics for each criterion that characterizes how well various alternatives satisfy the criterion. In addition, the enterprise establishes weighting factors for each criterion, which distinguish the degree of importance to the trade-off analysis definition. Models (representative or simulations) are established, when needed, to support conduct of a formal or informal trade-study. The selection of models depends on the nature of the trade-off analysis, the development stage, the type of information needed, and the characteristics of interest for an alternative. Models should be vahdated prior to application in a trade-off analysis. 

Fuel forms. The three alternative fuel forms for an LS-VHTR have very different characteristics and different refueling strategies. Trade studies will be required to determine the optimum reactor core and fuel configuration. Our preliminary assessment suggests that both pebble bed and stringer-type cores would be easier and faster to refuel than the Fort St. Vrain prismatic cores. 

Pre-program trade studies that were provided by contractors and NASA centers offered important inputs for HST project, since the submitted technical concepts addressed critical requirements and feasibility issues. 

Van Bossuyt DL, Turner lY, Wall SD (2013) A case for trading risk in complex conceptual design trade studies. Res Eng Des 24 259-275... 

Figure 23.5 is a flow diagram of the trade study process. To provide a basis for the selection criteria, the objectives of the trade study must first be defined. Functional flow diagrams and system block diagrams are used to identify trade study areas that can satisfy certain requirements. Alternative approaches to achieving the defined objectives can then be established. 

Complex approaches can be broken down into several simpler areas, and a decision tree constructed to show the relationship and dependences at each level of theselection process. This trade tree, as it is called, is illustrated in Fig. 23.6. Several trade study areas may be identified as possible candidates for accomplishing... 

FIGURE 23.5 Trade study process flow chart. Source Adapted from Defense Systems Management 1983. Systems Engineering Management Guide. Contract No. MDA 903-82-C-0339. Defense Systems Management College> Fort... 

Finally, the results of the trade study are documented in the form of a report, which discusses the reasons for the selections and may include the trade tree and the trade table. 

---