GLOBAL KNOWLEDGE ARK

Reference library

Foundations

Explore concepts, laws, equations and methods, with clear explanations of their use and sources. Choose an area of study or find a specific entry.

More filters

Reference entries

Showing 1501–1530 of 1709 reference entries

Earth & cosmosComparative planetary heat transport and observed phase curves

Planetary circulation couples radiation and dynamics; comparing advective, radiative and rotation time scales organizes possible regimes.

Method
Earth & cosmosSurvey selection in observed and intrinsic coordinates

A survey's detected density is the underlying observable distribution multiplied by a selection probability.

Method
Earth & cosmosActual 3D inversion: synthetic secret-model comparisons

The Dublin Secret Model 1 benchmark compares three actual 3D magnetotelluric reconstructions of a spiral conductor from synthetic impedance data.

Method
Earth & cosmosQAMT 2025: synthetic recovery and a field application

Schiffler and colleagues validate a 3D EM inversion implementation using five synthetic anomalies and compare recovered structures across survey observables.

Method
Earth & cosmosDark-sector models: compare evidence at each scale

GR with cold dark matter is the established cosmological comparison baseline.

Method
Earth & cosmosAcceleration models: fit and independent gravity tests

A constant Λ is the minimal GR acceleration baseline; dynamical fields require additional assumptions and parameters.

Method
Earth & cosmosRadiation–matter exchange in relativistic accretion

Radiation-GRMHD couples the matter-plus-magnetic stress tensor to a radiation tensor with opposite four-force sources, so their sum is covariantly conserved.

Method
Mathematics & logicReal-number arithmetic laws

Real arithmetic permits regrouping, distributing and taking nonzero reciprocals.

Mathematical statement
Mathematics & logicFinite decimal place value

A decimal digit's position determines its power-of-ten weight.

Definition
Mathematics & logicRational numbers and recurring decimals

Terminating or eventually recurring decimals represent exactly the rational numbers.

Mathematical statement
Mathematics & logicArithmetic with fractions

Fraction arithmetic preserves value by using common denominators or reciprocals.

Method
Mathematics & logicAbsolute value and distance intervals

Absolute value measures distance from zero on the real line.

Definition
Mathematics & logicPercent and relative change

A percentage states a ratio per hundred and needs an explicit base.

Method
Mathematics & logicOrder rules for real inequalities

Scaling an inequality depends on the factor's sign.

Mathematical statement
Mathematics & logicInteger powers and positive-base rational powers

Negative exponents use reciprocals; rational exponents use principal roots.

Definition
Mathematics & logicReal logarithms and their laws

A logarithm is the inverse of exponentiation for an admissible positive base.

Definition
Mathematics & logicQuadratic formula and discriminant

The discriminant classifies the real solutions of a quadratic equation.

Mathematical statement
Mathematics & logicFunction composition and inverses

Composition feeds one output into another function; inversion requires unique preimages.

Definition
Mathematics & logicEuclidean triangle congruence tests

Specified matching sides and angles can establish the same triangle shape and size.

Mathematical statement
Mathematics & logicEuclidean triangle similarity tests

Triangle similarity keeps corresponding angles and one common positive side scale.

Mathematical statement
Mathematics & logicAcute-angle right-triangle ratios

Opposite and adjacent legs depend on the chosen acute angle.

Definition
Mathematics & logicRadian angle, circular arc and sector

Radian measure is arc length divided by radius.

Definition
Mathematics & logicPlane area and perimeter formulas

Area measures covered surface; perimeter measures boundary length.

Mathematical statement
Mathematics & logicRight-prism and cylinder volumes

Volume and surface area measure different aspects of a solid.

Mathematical statement
Mathematics & logicDescriptive sample center and spread

Mean, median, mode and sample variance summarize observed values.

Method
InformationTwo's-complement signed integers

A signed interpretation assigns a negative weight to the highest bit.

Definition
InformationOctets and multi-byte order

Byte order describes the significance assigned to successive stored octets.

Definition
InformationUnicode scalar values and UTF-8

UTF-8 encodes scalar values with a variable number of octets.

Definition
InformationText boundaries and Unicode normalization

Text equality and character counts depend on the declared representation and convention.

Method
InformationIP addresses and datagram delivery

IP addresses identify network destinations; IP does not guarantee delivery.

Definition