Stability theoryIn mathematics, stability theory addresses the stability of solutions of differential equations and of trajectories of dynamical systems under small perturbations of initial conditions. The heat equation, for example, is a stable partial differential equation because small perturbations of initial data lead to small variations in temperature at a later time as a result of the maximum principle. In partial differential equations one may measure the distances between functions using Lp norms or the sup norm, while in differential geometry one may measure the distance between spaces using the Gromov–Hausdorff distance.
Load-following power plantA load-following power plant, regarded as producing mid-merit or mid-priced electricity, is a power plant that adjusts its power output as demand for electricity fluctuates throughout the day. Load-following plants are typically in between base load and peaking power plants in efficiency, speed of start-up and shut-down, construction cost, cost of electricity and capacity factor. Base load power plants are dispatchable plants that tend to operate at maximum output.
Low-head hydro powerLow-head hydropower refers to the development of hydroelectric power where the head is typically less than 20 metres, although precise definitions vary. Head is the vertical height measured between the hydro intake water level and the water level at the point of discharge. Using only a low head drop in a river or tidal flows to create electricity may provide a renewable energy source that will have a minimal impact on the environment.
Sympathetic resonanceSympathetic resonance or sympathetic vibration is a harmonic phenomenon wherein a passive string or vibratory body responds to external vibrations to which it has a harmonic likeness. The classic example is demonstrated with two similarly-tuned tuning forks. When one fork is struck and held near the other, vibrations are induced in the unstruck fork, even though there is no physical contact between them. In similar fashion, strings will respond to the vibrations of a tuning fork when sufficient harmonic relations exist between them.
Center of pressure (fluid mechanics)In fluid mechanics, the center of pressure is the point where the total sum of a pressure field acts on a body, causing a force to act through that point. The total force vector acting at the center of pressure is the surface integral of the pressure vector field across the surface of the body. The resultant force and center of pressure location produce an equivalent force and moment on the body as the original pressure field. Pressure fields occur in both static and dynamic fluid mechanics.
Unit loadThe term unit load refers to the size of an assemblage into which a number of individual items are combined for ease of storage and handling, for example a pallet load represents a unit load which can be moved easily with a pallet jack or forklift truck, or a container load represents a unit for shipping purposes. A unit load can be packed tightly into a warehouse rack, intermodal container, truck or boxcars, yet can be easily broken apart at a distribution point, usually a distribution center, wholesaler, or retail store for sale to consumers or for use.
ContainerizationContainerization is a system of intermodal freight transport using intermodal containers (also called shipping containers, or ISO containers). Containerization, also referred as container stuffing or container loading, is the process of unitization of cargoes in exports. Containerization is the predominant form of unitization of export cargoes, as opposed to other systems such as the barge system or palletization. The containers have standardized dimensions.
Water hammerHydraulic shock (colloquial: water hammer; fluid hammer) is a pressure surge or wave caused when a fluid in motion, usually a liquid but sometimes also a gas is forced to stop or change direction suddenly; a momentum change. This phenomenon commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. This pressure wave can cause major problems, from noise and vibration to pipe rupture or collapse.
Plastic modelA plastic model is a plastic scale model manufactured as a kit, primarily assembled by hobbyists, and intended for static display. A plastic model kit depicts various subjects, with a majority depicting military and civilian vehicles. A kit varies in difficulty, ranging from a "snap-together" model that assembles straight from the box, to a kit that requires special tools, paints, and cements. The most popular subjects of plastic models by far are vehicles such as aircraft, ships, automobiles, and armored vehicles such as tanks.
Model carA model car, or toy car, is a miniature representation of an automobile. Other miniature motor vehicles, such as trucks, buses, or even ATVs, etc. are often included in this general category. Because many miniature vehicles were originally aimed at children as playthings, there is no precise difference between a model car and a toy car, yet the word 'model' implies either assembly required or the accurate rendering of an actual vehicle at smaller scale.
