Factor of Safety

Example: Lift 
Photo source: First Avenue Mall, Penang

Figure 8.l shows the lift shaft

     Factor of Safety means that a design uses more element than needed to compromise for unexpected cases or system failure.
     In the lift system, there exists the factor of safety principle in this design, through the use of multiple metal cables (seen in Figure 8.1). This is because there are more than one metal cable used to support the lift even though 1 metal cable itself is capable to support a fully loaded lift on its own. Therefore, the multiple cables acts as a safety factor to minimize the failure of the system in case the lift is overloaded.

Redundancy

Redundancy is the use of extra elements than needed to keep the system performance in case one or more of the element fails.

Active Redundancy

Example: Truck
Photo source: Desa Ilmu 

Figure 8.2.1 shows a 18 wheeled truck.

     Active redundancy is the use of redundant elements all the time, means the redundant elements are always active.

     The truck in figure 8.2.1 shows the use of many tires to accommodate for its load. Similarly to using multiple independent pillars to support a roof, these tyres are the redundant elements and the burden of the load of the lorry is distributed to each of tyres. This will reduce system or element failure because the burden is not solely on one tyre at a time. 

  

Passive Redundancy

Example: Emergency lights

Photo source: FSS hallway

Figure 8.2.2 shows an emergency light.

     Passive redundancy is the use of redundant elements only when the active elements fails.

     The emergency lights in Figure 8.2.2 are used as redundant elements in this lighting system. In this case, the emergency lights acts as passive elements and the normal lights acts as active elements. In case of a blackout where the normal lights fail, then the emergency lights will light up. Therefore the emergency lights can be said as passive redundant elements because they are always idle until the normal lights fail.

Diverse Redundancy

Example: Phone alert system

Photo source: Friend's phone.

Figure 8.2.3 shows a mobile phone when it receives a call.

    Diverse redundancy is using different elements to resist a single cause of failure.

    Mobile phones (in Figure 8.2.3) uses a diverse redundancy principle in its alert system, for example when a phone receives a call. It uses sound, light and vibration all at the same time to alert the user about the incoming call.  For example, in case when the sound system of the phone fail to function, there are still vibration and lights to alert the user of the incoming call. Hence the diverse redundancy elements can be seen in terms of the various alert system of sound, light and vibration.

Homgeneous Redundancy

Example: Bicycle chain
Photo source: FSKPM

Figure 8.2.4 shows a bicycle chain.

     Homogenous redundancy is the use of multiple same elements to maintain the system's performance  in case of failure of one element.
     The bicycle seen in Figure 8.2.4 have a chain to operate its wheels. This chain consist of many  links (the small elements that make up the chain) that can be removed or added to adjust the length of the chain. In this example, the links are the homogenous redundant elements. This is because they can be attached back if one of the links is damaged. However, the chain is susceptible to one cause of failure, for example if the chain is cut, the chain will break and the bicycle will not function anymore.  

Flexibility

Example: Multi-Purpose Laptop Table
Photo Source: Own Laptop Table

Figure 8.3 shows the flexibility of the laptop table

     Flexibility in design enables the product to perform more function that they are intended to do.
     In this example, flexibility is seen in terms of the laptop table. As seen in Figure 8.3, the legs of the table are adjustable to any height suitable to the user, seen in the pictures above. Hence, it can be used on the floor, bed or even sofa. Besides that, the laptop table is also flexible such that it can be used as a breakfast-in-bed tray, reading desk or as a side table.

Usability Tradeoff

Example: 5 in 1 Highligher

Photo source: Own highlighter

Figure 8.4.1 shows a multi-coloured highlighter.

Figure 8.4.2 shows normal highlighters.

     Usability tradeoff is decreasing a product's usability in exchange for another benefit. Such example is to trade the product's usability for better flexibility.

     The multi-coloured highlighter in Figure 8.4.1 is flexible because it is mobile and has a lot of colours attached to just one highlighter. However, the usability of the highlighter is less when compared to an individual highlighter (Figure 8.4.2) because of its shape. It is more difficult for a user to grip the highlighter due to it's bulky shape than compared to an individual highlighter. Besides that, the ink on the multi-coloured highlighter tends to run out easily as it has smaller ink pad whereas an individual highlighter has a larger ink pad. Therefore its usability has been traded off for the sake of flexibility in terms of having more choice of colours. 

Satisficing

Example: Attached Nail File on Nail Clipper
Photo source: Own Nail Clipper

Figure 8.5.1 shows a nail clipper with an attached nail file.

Figure 8.5.2 shows a specialized nail file.

     Satisficing means settling for something we know it may not be the best possible but at the very least will satisfy our essential needs. Users generally will not always make the best choice; instead they will go for the one that is enough to satisfy our needs.
     Our example is the attached nail file on the nail clipper shown in Figure 8.51. This is because the nail file attached on the nail clipper are less usable and more difficult to use than compared to the individual nail file (Figure 8.5.2) which is more specialized and efficient. However, we still do use the nail file on the nail clipper whenever we do not have the desired individual tool or when the nail file is out of our reach. We know it may not be the best possible solution but we still use it because at least it works and we manage to reach our initial goal.

Ockham’s Razor

Example: Posters

Photo source: FSKPM notice board, CAIS notice board

 

Figure 8.6.1 shows a poster with a clean look.

Figure 8.6.2 shows a poster with many information.

    In
 design, 
Ockham’s
 Razor 
encourages 
us
 to
 eliminate
 unnecessary
 elements 
that
 would 
decrease
 a
 design’s
 efficiency.


 In the above example, figure 8.6.1 and figure 8.6.2 shows 2 different posters. They serve the same function, which is to inform the reader of something. However, the poster in figure 8.6.1 has a much cleaner look and is easier to read when compared to the other poster (figure 8.6.2). 

    The 1st poster has a QR code at the bottom right so that the reader that is interested to know more can scan the code. So the poster itself is not cluttered with too many elements. Compared to the 1st poster, the 2nd poster is cluttered with too many words making it looks messy and unattractive to read. Therefore we can see that the Ockham's Razor principle is applied in the 1st poster (figure 8.6.1) to make it simpler and more attractive compared to the 2nd poster in (figure 8.6.2).

Form Follow Function

Example: Water Bottle
Photo source: Friends' Water Bottle

Figure 8.7 shows different designs of water bottles

     In form follow function, the design of a product should consider the functionality first before the aesthetic component.
     Our example is the water bottle. The function of a water bottle is to 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 bottle comes in different designs and shapes (seen in Figure 8.7), it does not matter how the water bottle looks as long as it affords the user to store water.