NUST NET flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Young's modulus

Ratio of tensile stress to tensile strain in the linear-elastic region, E = σ/ε, measured in pascals. It describes a material's stiffness, not its strength.

Carnot efficiency

Maximum theoretical efficiency of a heat engine, 1 − T_cold/T_hot, with temperatures in kelvin. No real engine between the same reservoirs can exceed this value.

Two's complement

Binary scheme where a negative number is formed by inverting all bits and adding one. An n-bit signed integer ranges from −2^(n−1) to 2^(n−1)−1.

Binary search complexity

Searching a sorted array by repeatedly halving the interval takes O(log n) comparisons. It requires random access and a pre-sorted input.

Admissible heuristic

A heuristic that never overestimates the true remaining cost to the goal. A* search with an admissible heuristic is guaranteed to find an optimal path.

PID controller terms

Proportional term responds to current error, integral term removes steady-state offset, derivative term damps overshoot. Output = Kp·e + Ki·∫e dt + Kd·de/dt.

Convolution output size

For input width W, filter F, padding P, and stride S, the output width is (W − F + 2P)/S + 1. Applies per spatial dimension in a CNN layer.

pH definition

pH = −log₁₀[H⁺], where [H⁺] is hydrogen-ion concentration in moles per liter. A one-unit drop means a tenfold increase in acidity.

Beer–Lambert law

Absorbance A = εcl, where ε is the molar absorptivity, c the concentration, and l the path length. Absorbance scales linearly with concentration.

Water activity

Ratio of water vapor pressure in a food to that of pure water at the same temperature. Most bacteria require a_w above roughly 0.91 to grow.

D-value

Time at a specified temperature needed to reduce a microbial population by 90%, i.e., one log reduction. It quantifies heat resistance of a target organism.

Maillard reaction

Non-enzymatic browning between reducing sugars and amino groups, favored by heat and intermediate moisture. It produces color and flavor compounds in baked and roasted foods.

Golden ratio

Irrational number φ ≈ 1.618, where a rectangle's sides satisfy a/b = (a+b)/a. Often used as a proportion rule in classical and modern design.

First-angle projection

Technical drawing convention where the object sits between viewer and plane, so the top view appears below the front view. Third-angle places it above instead.

Scale 1:100

One unit on the drawing equals 100 units in reality. A 5 cm line on such a drawing represents 500 cm, or 5 metres, on site.

DNA base pairing

Adenine pairs with thymine via two hydrogen bonds; guanine pairs with cytosine via three. This complementarity underlies replication and transcription.

Mendelian 3:1 ratio

A monohybrid cross between two heterozygotes (Aa × Aa) yields phenotypes in a 3:1 ratio and genotypes in a 1:2:1 ratio, assuming complete dominance.

Photosynthesis equation

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂, occurring in chloroplasts. Light reactions make ATP and NADPH; the Calvin cycle fixes carbon.

Break-even quantity

Fixed costs divided by contribution margin per unit (price minus variable cost per unit). It is the sales volume at which total revenue equals total cost.

Current ratio

Current assets divided by current liabilities. A value below 1 suggests short-term obligations may exceed readily available liquid resources.

Price elasticity of demand

Percentage change in quantity demanded divided by percentage change in price. Demand is elastic when the absolute value exceeds 1, so revenue falls if price rises.

GDP expenditure identity

GDP = C + I + G + (X − M), summing consumption, investment, government spending, and net exports. It counts final output produced within a country's borders.

Contract elements

Offer, acceptance, consideration, intention to create legal relations, and capacity. Missing any element can prevent formation or make a contract voidable.

Ratio decidendi

The legal reasoning essential to a court's decision, which binds lower courts under stare decisis. Obiter dicta are incidental remarks and only persuasive.

Negligence elements

Duty of care owed by defendant, breach of that duty, factual and legal causation, and resulting damage. All four must be proved in a civil claim.

Actus reus and mens rea

The prohibited act or omission and the guilty mental state respectively. Most serious offences require both to be proved by the prosecution.

Stress and strain

Stress is force per unit area (Pa); strain is change in length divided by original length (dimensionless). Their ratio is Young's modulus in the elastic region.

Ohm's law

V = IR, where V is potential difference, I current, and R resistance. Series resistors add; parallel resistors combine as reciprocals.

Stack versus queue

A stack is last-in-first-out; a queue is first-in-first-out. Both support constant-time insertion and removal with an appropriate implementation.

Normalisation primary key

A primary key uniquely identifies each row and cannot be null. A foreign key references a primary key in another table or is null.

Half-life

Time for half of a radioactive sample to decay. After n half-lives the remaining fraction is (1/2)^n, following N = N₀e^(−λt).

HACCP seven principles

Hazard analysis, critical control points, critical limits, monitoring, corrective actions, verification, and record-keeping. It is a preventive food-safety management system.