Structure of the Design Process

Three core questions arise when reviewing the currently available design methods for RD processes. 

Regarding the second question, the output space of the design methodologies under consideration is mapped in table 3.2. It should be noticed that most of the methodologies focus on the estimation of spatial variables, paying less explicit attention to the temporal response of the design. Moreover, no method up to now has addressed exergy considerations for the case of RD. 

Structure includes the complete spatial structure of the process, together with the control loops and operating conditions (ie. ranges of temperature, pressure and reboil/reflux ratios). 

Performance involves the estimation of criteria related to safety, health, environment and economics. Technological aspects are addressed in the next category. This group of criteria are referred to as SHEET. 

Operability involves the ability to operate the unit(s) at preferred conditions in spite of disturbances and changes in operational policies. Availability is rarely considered and is a measure of the degree to which the unit(s) is in an operable state at any time. 

---

Code reuse is a sought-after goal, but it does not happen automatically. It costs money, and it requires explicit attention at the level of design and in the structure of the development process within and across projects. 

A clinical trial is an experiment and not only do we have to ensure that the clinical elements fit with the objectives of the trial, we also have to design the trial in a tight scientific way to make sure that it is capable of providing valid answers to the key questions in an unbiased, precise and structured way. This is where the statistics comes in and statistical thinking is a vital element of the design process for every clinical trial. 

The structure of a design process and its product is in most cases only determined in the process itself, as design decisions predetermine following processes and products. In the same way, made modifications or specific error repairs imply what and how to do. Hence, the process can only be partially fixed before it starts. We call this the dynamics within the process. 

Activities and their interdependencies. Due to their creative character, design processes are weakly structured In general, it is not possible to give a detailed descriptions of all activities a priori. For instance, the necessity to perform certain activities can depend on criteria which cannot be formulated before some intermediate results of the design process are available. 

We already discussed that the PPM should be structured into different layers, from application domain models to platform models (cf. Fig. 1.6). On every layer, there is a complete description of the product, i.e. the result of the design process overall configuration). Trivially, we find hierarchies on every layer. In top-down direction, from layer to layer, the number of details is growing. The model is transformed from layer to layer, from an explicit model to more implicit descriptions (code). The product is complemented by the associated design proce.s.s on every layer. Like the product, the process is hierarchically structured. An abstract process model is transformed into tool commands and corresponding code. 

The object-oriented data model CLiP (Conceptual Lifecycle Process Model) [14, 19] for product data of the design process and the corresponding work process, as described in Sects. 2.2 and 2.4, defines partial models structuring the engineering domain into several working areas. The relationships between the partial models are also contained in CLiP. For instance, there is a partial model Process Models (details below). Within Process Models, the model Activity and the model Actor are connected by the relationship skill. 

Afterward, the structure of the design projects is analyzed to identify recurring routine activities they are made available in the form of reference process components. Initially, this is done separately for both application partners. In a second step, similarities between the two application partners are identified. The validity and integrity of the collected parameters is increased through this process. In order to represent the design projects created in the first step, including influencing variables and process parameters, an appropriate software environment is identified. 

Figure 7.6 shows the Input/Output structure of the HDA process. Input streams are toluene and hydrogen. Outlet streams are benzene, diphenyl and purge. Toluene is pure, but hydrogen has 5% methane. The design decisions are (1) not purify the feed, (2) recycle hydrogen, and (3) consider purge for methane. 

Stages 2 and 3 of the design process (see Table 20.1) because they do not assume a controller structure or a specific controller design and tuning. 

The third stage of the design process concerns activities required to strategically select the structurally viable alternatives. These include engineering constructability analysis and life cost analysis of the alternatives. 

An important feature of Amical is maintaining links between the initial Vhdl description, the transition table, and the data-path. These links simplify the control of the design process when manual and automatic design is mixed. Through the information submenu, the user may ask for relationships between the synthesized structure and the scheduled description (see also section 3). 

P(3) Structural FRP components shall be fully designed and detailed prior to manufacture, except where full-scale testing or testing of prototypes forms part of the design process (see Chapter 7). In all cases, manufacture or fabrication of FRP components shall take account of the methods of erection and completion of the work so as to ensure coordination of the FRP work with that of related building elements. 

---