There were three big evaluation items. Systems Engineering, Boeing said did they did OK. Boeing’s JSF gave vertical lift by directing jet exhaust downward. LM blew air with a fan. But the biggest different was LM’s use of UML tools.
The bottom figure is on the state flag of Alaska.
Use cases should be named with verb phrases given in the active present tense form, from the point of view of the system or of the primary actor (depending on whose book you are reading). If you are using the view point of the primary actor, then the name should reflect the goal of that actor. Use case names should not relate to any particular solution. The verb should be in the imperative mood. Use case names are usually written with the first letter of each word capitalized and spaces between the words. It is helpful to set use case names in a different font. You should have a Goal or an Added value, but probably not both.
For the primary actor of BICS, Name: Sell HVAC Equipment and Services For the primary actor of Home Owner, Name: Buy and Operate HVAC System to Heat and Cool my House. Övergaard and Palmkvist (2005) state that use cases should be named from the perspective of the system. That is, they should state what the system is supposed to do. Thus, they would state that the Home Owner is the primary actor, and the name of the use case is “Sell HVAC Equipment and Services.” I don’t put the article “the” in front of the primary actor. Because, when the use case is instantiated with a person’s name, you would not want the “the.” For example, Pat Harris owns a house in Tucson.
This is a deliberate mistake. You cannot write requirements are things outside of your system, like the primary actor, the Home Owner.
The highest risk systems are most likely to change, forcing changes in other systems. If the highest risk systems cannot be completed successfully, cancel the project and save the money on developing the rest. In this mode of thinking, in the beginning also work on the optional functions. The contractor may back off.
In this presentation I am listing the creation date. You might prefer the last time it was changed.
The use case text is often called the use case specification. A use case model contains use case specifications, the use cases diagrams and perhaps other diagrams (e.g. flow charts, activity diagrams) and enclosures.
An important task is investigating alternative designs. For our HVAC system, we will also consider electric heat, wood, oil, coal, heat pumps, solar panels, three-phase electricity, steam, blankets, coats, hot or chilled water systems, fans, ice farms and cooling towers. According to the Regulate Temperature use case, depending upon which threshold is exceeded first, the system will sit at 70 or 73 degrees and turn the heater or AC on and off, maybe every second. If the system turns on and off every minute it would be very distracting to the people. So let’s require that it be on or off for at least 15 minutes at a time.
The goal is very much like the added value. You should use one or the other, not both.
Ethyl mercaptan = gas
The Nonfunctional performance requirement is new.
Supplemental entities that may be in the analysis model include functional flow block diagrams and object (context) diagrams.
The risk analysis shows that Ac air conditioning might cost as much as $7 per day. This may be too much for poor graduate students. Therefore we propose a piggyback system. On March 21 the Home Owner turns the Heater off and Evaporative Cooler on. For the next few months Tucson is very dry and the evaporative cooler cools the house very well. On June 21 the Home Owner turns the Evaporative Cooler off and Air Conditioner on. July and August are the monsoon season. It is humid and the evaporative cooler does work well, so we use the air conditioner. On September 21 the Home Owner turns the Air Conditioner off and Evaporative Cooler on. On November 21 the Home Owner turns the Evaporative Cooler off and Heater on.
The flag systemStatus would be system status in the business and requirements models.
In the Business Model the use-case diagram could be used as an outline for use cases you plan to develop. But in the Design Model it should be used as a table of contents for the use cases you have already written.
The title is purple, because this is a header slide.
Each row is a test specification. You can select any row, in any order.
State-based testing is the best. In state-based testing you start with an initial state and an input trajectory (a series of test vectors), then you run the experiment and observe the state trajectory.
When a use case is filled with specific names, dates, temperatures, etc. it is called an instantiation (based on the word instance).
The title is purple, because this is a header slide.
