ESE ME Prelims key terms

The tested ability to reason quantitatively, interpret data and graphs, apply basic numerical methods, and solve applied problems drawn from engineering contexts rather than from a single technical subject.

A method that groups physical variables into dimensionless products (Pi terms) so that experimental results or governing equations can be scaled between geometrically similar systems regardless of unit system.

A study of how variation in an input parameter changes the output of a model, used in aptitude problems on cost, optimisation, and decision-making under uncertainty.

The production quantity at which total revenue equals total cost, so profit is zero; computed as fixed cost divided by contribution per unit (price minus variable cost).

The systematic reduction in book value of an asset over its useful life, computed by methods such as straight-line, declining balance, or sinking fund, and used in economic comparison of alternatives.

The equivalent value today of a future stream of cash flows, obtained by discounting each flow at a chosen interest rate; used to compare investment alternatives on a common time basis.

A dimensionless ratio of inertial to viscous forces in a flow, Re = rhoVL/mu; it fixes the transition between laminar and turbulent regimes and governs dynamic similarity in model testing.

A statement of energy conservation along a steady, incompressible, frictionless streamline: pressure head plus velocity head plus elevation head stays constant; losses and pump work must be added when these assumptions fail.

A converging-diverging duct that measures discharge from the pressure difference between upstream and throat sections, using the Bernoulli relation with a discharge coefficient to correct for real losses.

The thin region near a solid surface where velocity rises from zero at the wall to the free-stream value, producing shear stress and, when it separates, increased drag and loss of lift.

Four times the flow cross-section divided by the wetted perimeter; it lets circular-pipe friction and heat-transfer correlations be applied to non-circular ducts and open channels.

Energy conservation for a system: heat added minus work done equals the change in internal energy (or, for a control volume, enthalpy plus kinetic and potential energy changes at steady flow).

A property measuring unavailable energy and irreversibility; it increases in any real adiabatic process and stays constant only in an idealised reversible adiabatic (isentropic) process.

The ratio of actual work output to the ideal work obtainable from an adiabatic device such as a turbine or compressor operating between the same inlet and exit pressures.

The ideal cycle for steam power plants: reversible adiabatic pumping, constant-pressure heat addition in the boiler, isentropic expansion in the turbine, and constant-pressure condensation.

The ratio of internal conduction resistance to external convection resistance, Bi = h*L/k; a small value justifies the lumped-capacitance assumption of uniform body temperature during transient cooling or heating.

A dimensionless heat-transfer coefficient, Nu = h*L/k, expressing convective heat transfer relative to pure conduction across the same length; it correlates with Reynolds and Prandtl numbers.

The constitutive relation for conduction: heat flux is proportional to the temperature gradient, with thermal conductivity as the constant of proportionality; the negative sign shows flow toward lower temperature.

The effective driving temperature difference for a heat exchanger, computed from the terminal differences of the two streams; it replaces the arithmetic mean when temperature varies along the flow path.

For two bodies in planar relative motion, the point about which one body appears to rotate at a given instant; locating it gives velocities of all points without solving full acceleration equations.

The extra acceleration component 2omegav arising when a point slides along a rotating link; neglecting it is a common error in velocity and acceleration analysis of slider-crank mechanisms.

The number of independent coordinates needed to specify a mechanism's configuration, given by Gruebler's or Kutzbach's criterion in terms of links and joint types.

The ratio of peak local stress at a geometric discontinuity to nominal stress in the same section; it depends on geometry and loading and is reduced by generous fillets.

A normal stress acting on a plane free of shear stress; its magnitude and direction come from Mohr's circle or eigenvalue solution of the stress tensor, and it governs failure criteria.

An equivalent scalar stress combining the three principal stresses, used in the distortion-energy criterion to predict yielding of ductile metals under multiaxial loading.

The cyclic stress amplitude below which a ferrous material survives an effectively infinite number of reversals without fatigue failure; non-ferrous metals generally show no such plateau.

An assembly in which the shaft diameter exceeds the hole diameter, creating radial pressure that transmits torque by friction and induces hoop and radial stresses in both parts.

The period for a poured metal to freeze, estimated by Chvorinov's rule as a constant times the ratio of volume to surface area squared; risers are sized from it.

The network of sprue, runner, and gates that delivers molten metal into a mould; its design controls fill rate, turbulence, and entrapment of slag and gas.

The approximate temperature (about 0.3 to 0.5 of the absolute melting point) above which a cold-worked metal forms new strain-free grains, restoring ductility and lowering strength.

The empirical relation V*T^n = C linking cutting speed V and tool life T, with exponent n and constant C depending on tool and workpiece materials; it underpins economic cutting-speed selection.

A force diagram for orthogonal machining relating cutting force, thrust force, friction on the rake face, and shear-plane force; it yields the shear angle and minimum-energy condition.

A quality programme targeting fewer than 3.4 defects per million opportunities by reducing process variation, organised around DMAIC phases and statistical process control tools.

A time-ordered plot of a process statistic with centre line and upper and lower limits, used to separate common-cause variation from assignable causes that demand corrective action.

A network scheduling technique identifying the longest-duration chain of dependent activities, which sets project duration and determines where float is zero and delay is costly.

For a stable queueing or production system, the average number of items in the system equals arrival rate times average time spent in it; useful for work-in-process and throughput estimation.

The systematic examination of method and time in a job, combining method study to simplify work and work measurement to set standard times for planning and incentives.

The arrangement of machines, storage, and service areas within a facility; process layout suits varied low-volume work, while product layout suits high-volume flow-line production.