An operation which consists in causing the collapse of the excavation ceiling, which thus fulfills the operating vacuum due to the blistering of the collapsed material. The collapse is caused by the withdrawal of the stock or by the use of explosives.

Ratio between total hours of absence and total hours worked (theoretical), according to the social report.

Part of the collector absorbs the solar radiation, converting it into what is delivered to the heat-carrying fluid.
Note: In the case of a flat sink, the absorbent surface is a dark and usually dull surface.

A device for utilizing wave energy which can absorb energy coming simultaneously from all directions with approximately equal yield and which is small in size compared to the average wave length. Note: Although a linear theory could demonstrate that an absorbing point draws energy from a wavefront having several times its width, it has not yet been possible to develop a practical system to realize it. This is due to non-linear behavior that invalidates theory for all wave amplitudes, except the weaker ones; these have no interest in the transformation of wave energy.

All work accidents, occurring at the service of the company (at the workplace or during working time), with low or fatal. In accidents involving casualty are included all accidents where the victim is unable to work for more than one day (not counting the day of the accident), including Saturdays, Sundays, holidays and other days when not normally work.

Integral curve of a chronological curve.

Average power in an alternating current circuit. In sinusoidal regime, it is equal to the product of the voltage by the active current in effective values. Note 1: The active current is the alternating current component that is in phase with the voltage. Note 2: is the power available for conversion into mechanical, thermal, chemical, light or sound energy.

Method in which the excavator extracts the material from its place of parking, by simple rotation of its extractor organ.

Water volumes that pass through a given section over a given period of time.

Crushed fuel obtained by compression, after preliminary preparation of a fuel of fine particle size, optionally mixed with a binder. The size of the agglomerates as well as their granulometry can be variable depending on their use.

An operation consisting of agglomerating a fuel having a fine particle size by giving it by pressure, with or without a binder, to obtain products of the same shape or size by pressure molding.

Part of the energy spectrum containing waves that were created by the wind that influence them (that is, they are produced in a recent time and at a short distance).

Environmental Impact Assessment

Turbine which, in most cases, triggers an electric generator that uses, as a motor fluid , compressed air by the pneumatic system designed to extract energy from the movements or the pressures of the waves.

Airline length, by voltage level (AT and MT), in the network owned by each distributor, within areas with nature protection status. In the European case, nature protection status is defined as the area legally classified as belonging to the Natura 2000 network and to the National Network of Protected Areas.

Fraction of direct or diffuse incident solar radiation flow, forwarded in all directions by reflection or diffusion on receiving surface. Note: Albedo is a practical notion that corresponds to the reflectance of a surface throughout the spectral range of the solar radiation without taking into account the variations related to the angle of incidence which may however be important.

Current whose polarity and intensity vary periodically in time. Note 1: It distinguishes between single-phase and three-phase current. Note 2: The usual frequencies are: 16 2/3, 50 and 60 Hz.