System Activity Diagram

The Business Layer is in the center of CRS where the core business functions reside. Any business application has a workflow—the steps it takes to accomplish one or many tasks or transactions. Clearly analyzing and understanding the workflow is essential to designing the Business Layer correctly. Use case specifications capture workflow from a user s perspective. The System Activity Diagram is an excellent tool to capture system workflow from a system perspective. Figure 12.1 is the System Activity Diagram (CAD) of CRS. 

Helgeson (1967) constructed an activity diagram depicting chemical equilibrium points (albite-sericite-K-feldspar and albite-sericite-Na-montmorillonite) of NazO-K20-Si02-Al203-H20 system at elevated temperatures. At these points,... 

Helgeson H. C., Brown T. H., and Leeper R. H. (1976). Handbook of Theoretical Activity Diagrams Depicting Chemical Equilibria in Geologic Systems Involving an Aqueous Phase at 1 atm and O to 300 °C. Freeman, Cooper, San Francisco. 

Fig. 2. Logarithmic activity diagram depicting equilibrium phase relations among aluminosilicates and sea water in an idealized nine-component model of tire ocean system at the noted temperatures, one atmosphere total pressure, and unit activity of H20. The shaded area represents (lie composition range of sea water at the specified temperature, and the dot-dash lines indicate the composition of sea water saturated with quartz, amotphous silica, and sepiolite, respectively. The scale to the left of the diagram refers to calcite saturation foi different fugacities of CO2. The dashed contours designate the composition (in % illite) of a mixed-layer illitcmontmorillonitc solid solution phase in equilibrium with sea water (from Helgesun, H, C. and Mackenzie, F T.. 1970. Silicate-sea water equilibria in the ocean system Deep Sea Res.).

Use case specifications can be visualized using UML Activity Diagrams and System Sequence Diagrams (Larman, 2005). I always find a graphic model easy to understand and communicate. However, these visualized models should be used as supplements, not as a replacement for use case specifications in text. 

Develop use case specification documents to capture detailed functional requirements (Chapter 9). Use System Sequence Diagrams and Activity Diagrams as complements. Use case specifications should be developed, communicated, and reviewed at the beginning of each iteration. 

The Idealized Fault-Tolerant Component diagram (see Figure 3) is a simple, indeed simplistic, structuring technique that shows one approach to distinguishing between various sorts of system interactions, in particular identifying and classifying those that relate to system activity aimed at error recovery. 

User Procedures for operating and maintaining the computer systems, control system, or laboratory system must be specified, approved, and where possible tested, before the systems are approved for use. User procedures can make good use of Role Activity Diagrams (RAD) to help readers understand the specific responsibilities associated with different roles. An example RAD is shown in Figure 4.3 in Chapter 4. 

Theoretical Activity Diagrams Depicting Geologic Systems Involving Aqueous Phases at One Atm and 0° to 300 C. 253 p. Freeman, Cooper and Co., San Francisco, 1969. 

Figu re 20.8 Top Triangular diagram of composition for the Mo/V/Nb(+Te orSb)/0 system, indicating the stoichiometry of compounds which form, and the area of existence for systems active and selective in alkanes oxidation and ammoxidation. Bottom detail of the top Figure. 

Helgeson, H. C., T. H. Brown, and R. H. Leeper. 1969. Handbook of theoretical activity diagrams depicting chemical equilibria in geological systems involving an aqueous phase at one atm and 0° to 300°C. San Francisco Freeman, Cooper Co. 

Figure 1. Activity diagram of jarosite-alunite-potassium feldspar-gibbsite-goethite system at 1 bar and 298 K. Modified from Bladh (18). Tailings pore water from Grants Mineral Belt, New Mexico and Maybell, Colorado are denoted by O and, respectively. Median ground water composition (19) is represented by. ...

Few liquid mixtures are ideal, so vapor-liquid equilibrium calculations can be more complicated than is the case for the hexane-triethylamine system, and the system phase diagrams can be more structured than Fig. 10.1-6. These complications arise from the (nonlinear) composition dependence of the species activity coefficients. For example, as a result of the composition dependence of y, the equilibrium pressure in a fixed-temperature experiment will no longer be a linear function of mole fraction. Thus nonideal solutions exhibit deviations from Raoult s law. We will discuss this in detail in the following sections of this chapter. However, first, to illustrate the concepts and some of the types of calculations that arise in vapor-liquid equilibrium in the simplest way, we will assume ideal vapor and liquid solutions (Raoult s law) here, and then in Sec. 10.2 consider the calculations for the more difficult case of nonideal solutions.. ... 

Figure 5. Qualitative activity-activity diagram for a portion of the system NaAlSi0u-CaAljtSi208-Si02-H20 for temperatures and pressures, mineral compositions implied by Figure 2...

Fig. 19.5. Equilibrium activity diagram for the system K20-Al203-Si02-H20 at 25°C, 1 bar (after Helgeson, 1979). The reaction path ABCDG represents successive stages in the hydrolysis of K-feldspar, which correspond to stages ABCDG in Figure 19.6.

Figure 2.3 Free energy versus composition and activity diagrams for a hypothetical eutectic system.

Figure 3.17 Activity diagrams for (a) systems with a non-stoichiometric phase and (b) systems forming intermetallic compounds.

Figure 3.5 (a) Process flow diagram of a RO-MVC system, (b) Process flow diagram of a MVC-RO system. Activated carbon and calcite filtration post-treatment not shown. 

The knowledge of the order of activities within the system often is important for safety assessment of the system based on SysML models. Useful diagrams to model the dynamic behaviour of systems that are provided by SysML are state machine diagrams, sequence diagrams, use case diagrams and activity diagrams. 

Generating the activity diagram can be imderstood as the first step towards the modeUing of dynamic system behaviour of the system. It can be used to model the activities that are performed by the system on an abstract level. Later it can be used to identify the presence of often recommended fallback or backup actions. 

FIGURE 10 Schematic diagram of typical wastewater treatment system. The secondary system schematic diagram is for an activated siudge process, a type of suspended growth process. Attached growth systems recycie the effiuent stream rather than the settied soiids stream. 

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