CHAPTER 8:DECISIONS

Factor Of Safety
*The use of more elements than is thought to be necessary to offset the effects of unknown variables and prevent system failure.
* Minimize the probability of failure in design, help to reduce safety factor with caution.

Small water dispenser - This water dispenser was BPA free to protect from substance obtained in a chemical process. Its shows that factor of safety exist because the element that been used to mention factor of safety with caution.

Redundancy
*The use of more elements than necessary to maintain the performance of a system in the event of failure of one or more of the elements.
*There are four kinds of redundancy:
1. Diverse 

This road map shows that exist diverse redundancy because its use of multiple element of different types. The maps guide user with the different road and time its take. 

2. Homogenous 

Multiple of cloth with varieties of color needs to make a door mat. Its fullfill the homogenous type  of redunadancu that use of multiple elements of a single type

3. Active 

Active redundancy type is the application of redundant elements at all times. For example, four single wood or "table's leg" was used to support the table. The table cannot stand if one of the table's legs was broken. 

4. Passive 

Passive redundancy type is the application of redundant elements "only" when an active element fails. The new staples is one of the examples of passives redundancy. New staples only will used when it is needed.

Flexibility - Usability Trade-off
*As the flexibility of a system increases, the usability of the system decreases.
*Problems:

• Added complexity in design
• More difficult to use.
• Decreased efficiency.
• Increased design time and cost.

Image at the left is less flexible because it has few applications but it has higher usability, compare to image at the right is more flexible with more application but the usability is low. 

Satisficing

*It is often preferable to settle for a satisfactory solution, rather than pursue an optimal solution.

*3 types of problems for which satisficing should be considered:

• Very complex problems - Characterized by a large number of interacting variables.
• Time-limited problems - Characterized by time frames.
• Problems for which anything beyond a satisfactory solution yields diminishing returns - Usability(speed and accuracy) vs aesthetics (style)

The design of the textliner was very simple, but we still choose it because we do not care about the design as long it can function as we want.

Ockham's Razor

This type of element is kind type of Ockham's Razor because its given choice between functionally equivalent designs which is this type functioned to cut the can easily. This type the simplest design that should be selected. 

Form Follows Function

*Beauty in design results from purity of function.

*The descriptive interpretation

•  that beauty results from purity of function
• was originally based on the belief that form follows function in nature.

*The prescriptive interpretation

• that aesthetic considerations in design should be secondary to functional considerations
• was likely derived from the descriptive interpretation.

Our example is the water bottle. The function of a water is ti store water. Therefore, the design of a water bottle first and foremost must ensure that the water bottle can store and keep water. As water comes if different designs and shapes, it does not matter as long as it affords the user to store water.