Engineering Dictionary

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An alphabetical listing of General terms and items.

DAC   Dico Tools
DAC, in accounting, is an acronym for Deferred Acquisition Costs.

Damping   Dico Tools
The reduction of vibratory movement through dissipation of energy. Types include viscous, coulomb, and solid.

Danske   Dico Tools
The sewage tower of a castle constructed by the Teutonic Knights, which was detached from the main body of the castle, and was only accessible by a gallery supported by five large arches.

Data Base   Dico Tools
A large amount of data stored in a well-organized manner. A data base management system (DBMS) is a program that allows access to the information.

DB (Decibel)   Dico Tools
20 times the log to the base 10 of the ratio of two voltages. Every 20 dBs correspond to a voltage ratio of 10, every 10 dBs to a voltage ratio of 3.162. For instance, a CMR of 120 dB provides voltage noise rejection of 1,000,000/1. An NMR of 70 dB provides voltage noise rejection of 3,162/1.

DC   Dico Tools
Direct current; an electric current flowing in one direction only and substantially constant in value.

Dead Angle   Dico Tools
The angle between the top of a fortification wall and where the defenders on the top of the wall ceased to be able to be able to bring their fire to bear upon the enemy approaching the walls. See dead ground.

Dead Band   Dico Tools
1. For chart records

Dead End Corridor   Dico Tools
A corridor which was situated on the inside of a fortifications gateway, which ended in dead ends, thus when an enemy force broke through the main gate and entered the corridor they were confused and trapped in a specialized killing ground.

Dead Ground   Dico Tools
Any area of a fortification where the enemy could not be attacked by the defenders, which was due to either the design or the siting of the work. Dead ground could be reduced by the use of hoardings, flanking towers or some other flanking defences. See dead angle, flanking.

Dead Volume   Dico Tools
The volume of the pressure port of a transducer at room temperature and ambient barometric pressure.

Deblai   Dico Tools
The ditch which was excavated when constructing the earthen ramparts of a work, the earth from the ditch was thrown inwards to form the rampart. See remblai.

Debug   Dico Tools
To find and correct mistakes in a program.

Debye-Hckel Equation   Dico Tools
Used in relating the activity coefficient (fi) to ion strength (see Activity coefficient):where I is the ionic strength, A and B the temperature-dependent constants (see Table A.5), Zi the valence of the ion (i), and A the ion-size parameter in angstroms.

Decimal   Dico Tools
Refers to a base ten number system using the characters 0 through 9 to represent values.

Deck   Dico Tools
Supported roadway on a bridge

Declivity   Dico Tools
The open slope from the covered way to the country surrounding a fortification, on which an assaulting force was completely exposed to the fire of the defenders. Also known as the glacis.

Decumanus Maximus   Dico Tools
The centre line of a Roman fortification.

Default   Dico Tools
The value(s) or option(s) that are assumed during operation when not specified.

Defence (Lines Of)   Dico Tools
A series of fortified outposts. See lines of defence (3).

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Defence, Defense   Dico Tools
The fortifications that provide cover for the opposite flanks, parapet, casements, etc.

Defencework   Dico Tools
Literally, a fortification; a work which was used to defend a position. See works.

Defilade   Dico Tools
To secure a work or part of against enfilade fire. See enfilade, traverse (1).

Deform   Dico Tools
To change shape

Degree   Dico Tools
An incremental value in the temperature scale, i.e., there are 100 degrees between the ice point and the boiling point of water in the Celsius scale and 180 F between the same two points in the Fahrenheit scale.

Dehor   Dico Tools
Any work (eg. crownwork, hornwork, halfmoon, ravelin, etc.) which was used to increase the defensibility of a fortification.

Demi-bastion   Dico Tools
A half bastion consisting of one face and one flank. See bastion.

Demi-caponier   Dico Tools
A caponier which was only protected on one side. See caponier.

Demi-gorge   Dico Tools
(1) A half a gorge; the area between the curtain angle and the centre of the bastion. See gorge. (2) The rear entrance of a bastion.

Demi-lune   Dico Tools
A work in the shape of a halfmoon which was used to defend the entrance of a fortification. Later, the demilune developed into a detached work called a ravelin which was situated within the line of the main ditch and was formed by two faces meeting in an outward angle, its purpose was mainly to cover the curtain it fronted and to prevent the flanks from being attacked from the side. Also known as a halfmoon. (L. Luna, moon).

Demi-revetment   Dico Tools
The partial facing of a rampart with concrete or masonry when it was raised only as the cover in front. See revetment.

Density   Dico Tools
Mass per unit of volume of a substance. I.E.

Derivative   Dico Tools
The derivative function senses the rate of rise or fall of the system temperature and automatically adjusts the cycle time of the controller to minimize overshoot or undershoot.

Descents   Dico Tools
(1) The cavities and mines made by members of a besieging force, which undermined the ground under the walls of the fortification being besieged. (2) Saps excavated in the counter scarp beneath the covered way, made by the besiegers to enable them to cross the ditch.

Detached Bastion   Dico Tools
(1) A bastion isolated from the main works by a ditch. See bastion. (2) Counterguards provided with flanks are also called detached bastions.

Detached Redout   Dico Tools
A small work sited beyond the glacis but within musket shot of the covert way, similar to a ravelin with flanks. See redout:

Detached Scarp   Dico Tools
A wall in a ditch which was separated from the glacis of the parapet by a pathway.

Detached Work   Dico Tools
An outwork which was separated from the main works, such as a ravelin. See forework, outwork, ravelin, works.

Deterrence Effect   Dico Tools
The effect of strong appearing military architecture which psychologically deters an enemy from attaching, especially used on gateways.

Deviation   Dico Tools
The difference between the value of the controlled variable and the value at which it is being controlled.

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Diaphragm   Dico Tools
The sensing element consisting of a membrane which is deformed by the pressure differential applied across it.

Dielectric Constant   Dico Tools
Related to the force of attraction between two opposite charges separated by a distance in a uniform medium.

Differential   Dico Tools
For an on/off controller, it refers to the temperature difference between the temperature at which the controller turns heat off and the temperature at which the heat is turned back on. It is expressed in degrees.

Differential Input   Dico Tools
A signal-input circuit where SIG LO and SIG HI are electrically floating with respect to ANALOG GND (METER GND, which is normally tied to DIG GND). This allows the measurement of the voltage difference between two signals tied to the same ground and provides superior common-mode noise rejection.

Differential Pressure   Dico Tools
The difference in static pressure between two identical pressure taps at the same elevation located in two different locations in a primary device.

Digit   Dico Tools
A measure of the display span of a panel meter. By convention, a full digit can assume any value from 0 through 9, a 1/2-digit will display a 1 and overload at 2, a 3/4-digit will display digits up to 3 and overload at 4, etc. For example, a meter with a display span of 3999 counts is said to be a 3-3/4 digit meter.

Digital Output   Dico Tools
An output signal which represents the size of an input in the form of a series of discrete quantities.

Digital-to-Analog Converter (D/A Or DAC)   Dico Tools
A device or circuit to convert a digital value to an analog signal level.

Dike, Dyke   Dico Tools
A work consisting of a ditch and rampart. See ditch, dyke, rampart. (O.N. dik, dam).

Diminished Angle   Dico Tools
The angle formed by the front and the exterior side of a bastion.

DIN (Deutsche Industrial Norm)   Dico Tools
A set of German standards recognized throughout the world. The 1/8 DIN standard for panel meters specifies an outer bezel dimension of 96 x 48 mm and a panel cutout of 92 x 45 mm.

DIN 43760   Dico Tools
The standard that defines the characteristics of a 100 ohm platinum RTD having a resistance vs. temperature curve specified by a = 0.00385 ohms per degree.

Discharge Time Constant   Dico Tools
The time required for the output-voltage from a sensor or system to discharge 37% of its original value in response to a zero rise time step function input. This parameter determines a low frequency response.

Disk Operating System (DOS)   Dico Tools
Program used to control the transfer of information to and from a disk, such as MS DOS.

Displacement   Dico Tools
The measured distance traveled by a point from its position at rest. Peak to peak displacement is the total measured movement of a vibrating point between its positive and negative extremes. Measurement units expressed as inches or millinches.

Dissipation Constant   Dico Tools
The ratio for a thermistor which relates a change in internal power dissipation to a resultant change of body temperature.

Dissociation Constant (K)   Dico Tools
A value which quantitatively expresses the extent to which a substance dissociates in solution. The smaller the value of K, the less dissociation of the species in solution. This value varies with temperature, ionic strength, and the nature of the solvent.

Ditch   Dico Tools
A wide trench excavated along the outer perimeter of a fortification, which was utilised to impede the approach of an enemy force towards the walls. The ditch was either filled with water or left dry. And if the ramparts were earthen the soil removed from the ditch was used to raise the ramparts. See moat. (O.E. dic, dike).

Diversion Channel   Dico Tools
A bypass created to divert water around a dam so that construction can take place

DMA   Dico Tools
Acronym direct memory access. A high speed data storage mode of the IBM PC.

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Dobei   Dico Tools
A wall made by daubing clay over a reed or bamboo framework and topped by a small tiled roof. This type of wall were used in two different parts of a Japanese castle

Dodecagon   Dico Tools
A fortification of twelve sides.

Dome   Dico Tools
A curved roof enclosing a circular space; a three-dimensional arch

Donjon   Dico Tools
The main defensible building of a fortification (the main tower or citadel), which was used as the Lords residence or as the last refuge if the outer defences fell to the attackers. The word is derived from the Latin word for lord `dominus'. The term was later corrupted to dungeon, as prisoners were often kept in the lower levels of the tower. Also known as the keep or great tower. See keep, mote.

Door Beam   Dico Tools
A beam for securing the doors of a fortification. The beam usually fitted into sockets on either side of the entrance and into brackets on the door itself.

Dshinn   Dico Tools
One of the three major types of Japanese castles which date from around 1600 A.D., which was constructed using a plan of three fortified compounds arranged in concentric pattern; the honmaru in the centre was surrounded by the ninomaru which in turn was surrounded by the sannomaru, variations on this occurred depending on the site.

Double Cross Gun Loop   Dico Tools
Similar to the 'cross and orb gun loop' but the vertical slit rose approximately twice the height and was provided with cross slits, one at the top, and the second a third of the way down. See cross and orb gun loop, gun loop.

Double Precision   Dico Tools
The degree of accuracy that requires two computer words to represent a number. Numbers are stored with 17 digits of accuracy and printed with up to 16 digits.

Downstream Face   Dico Tools
The side of the dam that is not against the water

Dozo-zukuri   Dico Tools
Since most of the buildings of a Japanese castle were mainly constructed of wood there was the necessity of reducing the risk of fire. This was accomplished by the technique of covering the walls and timbers with a thick layers of plaster. The plastering was used as a protection against domestic fires as well as those caused by the incendiary missiles of an enemy.

Draw Bolted Doors   Dico Tools
Doors which were used to defend an entrance of a fortification which were secured by draw bolts, such as those of a forebuilding of a keep.

Drawbridge   Dico Tools
A bridge which was used to provide access to a fortification, and when in the raised position it closed the entrance. Generally, a drawbridge was hinged at the bottom and free at the top, and could be drawn up to prevent and enemy gaining entry. The drawbridge usually spanned a ditch or moat, or the part of a ditch or moat between the fortification and a causeway. Its simplest form it consisted of a movable plank; others were pulled up by chains worked by pulleys or a windlass. A later development was the hinged platform; which could be raised by pulling up chains attached to the outer corners, these chains passed through slots above the entrance and were attached to a windlass in the chamber above the entrance. The most elaborate type worked on a counterpoise system; the chains were suspended from beams which, when the bridge was drawn up, fitted into recesses provided above the entrance. Another type worked on the pivot principle, where the inner part of the bridge was moved into a pit while the outer part rose to completely cover the entry, also known as a turning bridge (L. pontem torneicuim). See bascule bridge, hinged bridge.

Drift   Dico Tools
A change of a reading or a set point value over long periods due to several factors including change in ambient temperature, time, and line voltage.

Droop   Dico Tools
A common occurrence in time-proportional controllers. It refers to the difference in temperature between the set point and where the system temperature actually stabilizes due to the time-proportioning action of the controller.

Drop Box   Dico Tools
A feature in gatehouses and barbicans, consisting of holes through the floor of the structure over the entry, that were used to drop missiles and other offensive materials on the enemy below. See meurtrires, murder holes.

Drum Tower   Dico Tools
A squat round tower which was used as a flanking tower for curtain walls, gatehouses and barbicans. See flanking tower.

Dual Element Sensor   Dico Tools
A sensor assembly with two independent sensing elements.

Dual-slope A/D Converter   Dico Tools
An analog-to-digital converter which integrates the signal for a specific time, then counts time intervals for a reference voltage to bring the integrated signal back to zero. Such converters provide high resolution at low cost, excellent normal-mode noise rejection, and minimal dependence on circuit elements.

Dump   Dico Tools
See glacis, rampart.

Dun, D?n, D?in, Dh?in   Dico Tools
A fort dating from the late Iron Age, which are found in the west and the south-west of Scotland. It provided protection for a family or a small group. Similar in construction to a broch, a dun had a diameter of about 18 metres, and a narrow doorway angled through the dry stone wall, the walls were up to 4.5 metres thick. Usually circular or `D' shaped, they were frequently built on coastal headlands. The dun was different from hill forts mainly because of their smaller size and the complexity of their internal lodgings. See broch, hill fort. (Gaelic. d?n, fortress).

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Duplex   Dico Tools
Pertaining to simultaneous two-way independent data communication transmission in both direction. Same as "full duplex".

Duplex Wire   Dico Tools
A pair of wires insulated from each other and with an outer jacket of insulation around the inner insulated pair.

Duty Cycle   Dico Tools
The total time to one on/off cycle. Usually refers to the on/off cycle time of a temperature controller.

Dwingel   Dico Tools
A bent barbican dating from the 14th century. See barbican.

Dyke   Dico Tools
A defensive earthworks which covered long distances, consisting of ditches and ramparts. (O.N. dik, dam).

Dynamic (Two-Plane) Balancing Machine   Dico Tools
A dynamic balancing machine is a centrifugal balancing machine that furnishes information for performing two-plane balancing.

Dynamic Calibration   Dico Tools
Calibration in which the input varies over a specific length of time and the output is recorded vs. time.

Dynamic Pressure   Dico Tools
The difference in pressure levels from static pressure to stagnation pressure caused by an increase in velocity. Dynamic pressure increases by the square of the velocity.

Dynamic Unbalance   Dico Tools
Dynamic unbalance is that condition in which the central principal axis is not coincident with the shaft axis.

Dynamite   Dico Tools
A blasting explosive, based on nitroglycerin, but much safer to handle than nitroglycerin alone

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