HKDSE DAT flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Design brief
- A short statement of the problem, target user and intended outcome that starts a design project. It sets direction without prescribing the solution, so it should be agreed before research begins.
- Design specification
- A detailed list of measurable requirements a product must meet, split into constraints that must be satisfied and weighted criteria used to compare alternative solutions objectively.
- Iterative design cycle
- A repeating sequence of research, ideation, modelling, testing and evaluation. Results from testing feed back to earlier stages so the design is refined rather than fixed after one pass.
- Morphological analysis
- A technique listing each design parameter as a row and possible options as columns. Combining options across rows systematically generates many alternative configurations that might otherwise be overlooked.
- Anthropometric data
- Human body measurements such as reach, stature and grip span, usually given as percentiles. Designers use ranges from small users to large users so products fit most of the population.
- Design fixation
- Premature attachment to an early idea, which narrows later exploration. It is reduced by delaying judgement, generating many ideas quickly and deliberately combining unrelated concepts.
- Weighted decision matrix
- A comparison table scoring each concept against criteria, multiplying each score by the criterion weight and summing the results. The highest total indicates the best-balanced choice.
- Function analysis
- Describing what a product must do as verb–noun pairs, independent of how it is made. This separates essential functions from particular solutions and helps generate alternatives.
- Registered design
- A legal right protecting the visual appearance of a product, such as shape, pattern or ornamentation. It does not protect how the product works, which is the role of a patent.
- Patent
- A time-limited legal monopoly granted for an invention that is new, involves an inventive step and is industrially applicable. It excludes others from making or selling the invention.
- Embodied energy
- The total energy consumed in extracting, processing, manufacturing and transporting a material or product. Comparing embodied energy helps designers choose lower-impact materials and processes.
- Design for disassembly
- Designing products so parts can be separated easily for repair, reuse or recycling. It favours reversible fasteners over adhesives and identifies materials clearly on components.
- Ferrous metal
- A metal containing iron as its main element, such as steel and cast iron. Ferrous metals are magnetic and corrode to rust unless alloyed or given a protective coating.
- Thermoplastic
- A polymer whose long chains are not cross-linked, so it softens when heated and can be remoulded repeatedly. Examples include polyethylene, polypropylene, PVC and ABS.
- Thermosetting plastic
- A polymer with permanent cross-links between chains. Once cured it cannot be softened or remoulded by heat; epoxy resin and melamine are common examples used for heat resistance.
- Injection moulding
- A process where melted thermoplastic is forced into a closed metal mould under pressure. It suits high-volume production of complex parts but has high tooling cost.
- Vacuum forming
- A heated thermoplastic sheet is drawn onto a mould by suction and cooled. It is economical for large, shallow shapes such as trays and packaging but leaves trimmed waste.
- Extrusion
- Molten material is pushed through a die to produce a continuous length with a constant cross-section, such as pipes, window frames and heat sinks.
- Blow moulding
- A heated plastic tube is inflated inside a mould cavity so it takes the mould's shape. The process is used for hollow articles such as bottles and containers.
- Brinell hardness
- A hardness test pressing a hardened ball into the surface under a known load and measuring the indentation diameter. The result is reported as an HB number.
- Young's modulus
- The ratio of stress to strain in the elastic region of a stress–strain curve. It measures stiffness: a steeper gradient means a stiffer material.
- Gear ratio
- The number of teeth on the driven gear divided by the number on the driver gear. A ratio above one reduces output speed and increases output torque.
- Worm drive
- A screw-like worm meshing with a toothed wheel. It gives a large speed reduction in a compact space and usually cannot be driven backwards from the output shaft.
- Triangulation
- The use of triangular frames in a structure. Because a triangle cannot change shape without changing side lengths, triangulated trusses resist distortion and are rigid.
- Tension and compression
- The two basic forces in structural members. Tension pulls a member apart along its length; compression pushes it together. A beam under bending has both, on opposite sides.
- Ohm's law
- The relationship V = IR, where V is voltage in volts, I is current in amperes and R is resistance in ohms. It applies to resistive components at constant temperature.
- Series and parallel resistance
- In series, resistances add directly. In parallel, the reciprocals add: 1/RT = 1/R1 + 1/R2. Parallel branches share current and each sees the same voltage.
- Potential divider
- Two resistors in series across a supply, where output voltage is taken across one resistor. Vout = Vin × R2/(R1 + R2), used to provide a smaller reference voltage.
- Logic gates
- Digital building blocks applying Boolean rules. AND outputs 1 only when all inputs are 1; OR when any input is 1; NOT inverts; NAND and NOR are inverted AND and OR.
- Soldering versus brazing
- Soldering melts filler below about 450 °C; brazing uses higher temperatures. Neither melts the parent metal, unlike welding, which fuses the joined materials themselves.
- Rapid prototyping
- Additive manufacturing that builds a part layer by layer from a digital model. It enables fast physical testing of form and fit before committing to expensive production tooling.
- Quality control
- Planned inspection and measurement activities that check products against specifications. Techniques include sampling, tolerance checks, go/no-go gauges and statistical process control.