8.2 Assessing whether a design solution meets the criteria of technical specifications

Key terms

1. Functionality The functionality of a product can be described as 'The purpose that something is designed or expected to fulfil'.

1. Accuracy: Accuracy has two definitions.
   1. More commonly, it is a description of systematic errors, a measure of statistical bias; as these cause a difference between a result and a "true" value, ISO calls this trueness.
   2. Alternatively, ISO defines accuracy as describing a combination of both types of observational error above (random and systematic), so high accuracy requires both high precision and high trueness.
   3. In simplest terms, given a set of data points from repeated measurements of the same quantity, the set can be said to be precise if the values are close to each other, while the set can be said to be accurate if their average is close to the true value of the quantity being measured. The two concepts are independent of each other, so a particular set of data can be said to be either accurate, or precise, or both, or neither.

1. Performance: Performance engineering encompasses the techniques applied during a systems development life cycle to ensure the non-functional requirements for performance (such as throughput, latency, or memory usage) will be met. It may be alternatively referred to as systems performance engineering within systems engineering, and software performance engineering or application performance engineering within software engineering.
   1. As the connection between application success and business success continues to gain recognition, particularly in the mobile space, application performance engineering has taken on a preventative and perfective role within the software development life cycle. As such, the term is typically used to describe the processes, people and technologies required to effectively test non-functional requirements, ensure adherence to service levels and optimize application performance prior to deployment.
   2. The term performance engineering encompasses more than just the software and supporting infrastructure, and as such the term performance engineering is preferable from a macro view. Adherence to the non-functional requirements is also validated post-deployment by monitoring the production systems. This is part of IT service management.
   3. Performance engineering has become a separate discipline at a number of large corporations, with tasking separate but parallel to systems engineering. It is pervasive, involving people from multiple organizational units; but predominantly within the information technology organization.

8.2b Recognise how physical testing systems are integrated into the manufacturing process to test functionality

Destructive Testing

1. In destructive testing (or destructive physical analysis, DPA) tests are carried out to the specimen's failure, in order to understand a specimen's performance or material behaviour under different loads. For example, when testing a new washing machine, some destructive tests might be:
   1. Repeated opening/closing of door (by robotic mechanism) until failure.
   2. Tensile testing of belt until failure.
   3. Time-to-failure tests of the washing machine.
   4. Overload tests (excess laundry).
   5. Product shake/vibration tests for unbalanced load.
   6. Temperature overheat tests.
   7. Fire tests.
   8. Electrical voltage overload tests to test for electrical safety.

Non-destructive testing

1. Non-destructive testing (NDT) is a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage. For example, when testing a new washing machine, some non-destructive tests might be:
   1. Basic functional tests.
   2. Leak tests.
   3. Failsafe tests – checking that machine stops under unsafe conditions.
   4. Temperature cut-out tests.
   5. Load imbalance sensor tests.
   6. Water overfill cut-out.
   7. Door interlock tests.
   8. Visual quality control checks at stages of manufacture.
   9. Quantitative testing at stages of manufacture.
   10. PCB testing.
   11. Testing for software upgrades.

Testing materials durability

1. It is generally considered a subset of reliability testing. Durability Testing is a Performance testing technique used to determine the characteristics of a system under various load conditions *over time*. This testing helps us to identify the stability of transaction response times over the duration of the test.

Testing models and prototypes for performance and fitness purposes

1. Model-based testing is an application of model-based design for designing and optionally also executing artefacts to perform software testing or system testing. Models can be used to represent the desired behavior of a system under test (SUT), or to represent testing strategies and a test environment.

Testing products in use through different methods

1. Consumer testing is testing or comparative testing, is a process of measuring the properties or performance of products. The theory is that since the advent of mass production manufacturers produce branded products which they assert and advertise to be identical within some technical standard.
2. Virtual testing is a process in which your product is tested on various characteristics, such as drop resistance, failure behaviour or deformations using a CAD model of a product rather than testing on the product itself. Numerical models are used to verify the performance of the product. E.g. Simulating how the crumple zones in a car will buckle in different types of crash.

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