火災(zāi)報(bào)警器中英文文獻(xiàn)翻譯--基于單片機(jī)的火災(zāi)探測(cè)和監(jiān)控系統(tǒng)-單片機(jī)-文庫(kù)吧
2025-04-16 21:36 本頁(yè)面
【正文】 design. This implementation was not possible with old technology. Most of fire detection/monitoring systems available are tailored towards a specific application and lack the use of recent advances in CMOS VLSI technology. In this study, we develop a fire detection/monitoring system which is general in concept, readily implementable in a multitude of applications for early detection of a fire before it bees critical, for equipment and evacuation of personnel. Here, we propose a central control and distributed control/detection/monitoring with adequate munication, where use is made of singlechip microcontrollers in the local stations, thus improving controllability and observability of the monitoring process. 2 Detection and alarm devices A basic fire detection system consists of two parts, detection and annunciation. An automatic detection device, such as a heat, smoke or flame detector, ultraviolet or infrared detectors or flame flicker, is based on detecting the byproduct of a bustion. Smoke detectors, of both ionization and optical types, are the most monly used detector devices. When a typical detector of this type enters the alarm state its current consumption increases from the pA to the mA range (say, from a mere 15pA in the dormant mode to 60 mA) in the active mode. Inmany detectors the detector output voltage is well defined under various operating conditions, such as those given in Table 1. The more sensitive the detector, the more susceptible it is to false alarms. In order to control the detector precisely, either of the following methods is used: a coincidence technique can be built into the detector, or a filtering technique such that a logic circuit bees active only if x alarms are detected within a time period T. The detection technique depends greatly on the location and plant being protected。 smoke detectors are used for sleeping areas, infrared or ultraviolet radiation are used when flammable liquids are being handled, heat detectors are used for fire suppression or extinguishing systems. In general, life and property protection have different approaches. Alarm devices, apart from the usual audible or visible alarms, may incorporate solid state sound reproduction and emergency voice munication or printers that record time, date, location and other information required by the standard code of practice for fire protection for plex plants. Heaviside [4] has an excellent review of all types of detectors and extinguisher systems. Control philosophy and division of labour Our control philosophy is implemented hierarchically. Three levels of system hierarchy are implemented, with two levels of decision making. There is no munication between equipment on the same level. Interaction between levels occurs by upwards transfer of information regarding the status of the subsystems and downwards transfer of mands. This is shown in Fig. 1 where at level 1 is the central station microputer and is the ultimate decision maker (when not in manual mode). At level 2 are the local controllers, which reside in the local stations. At level 3 are the actual detectors and actuators. A manual mode of operation is provided at all levels. Information regarding the status of all detectors is transmitted on a per area basis to the local controllers. Their information is condensed and transmitted upward to the central microputer. Transfer of status is always unidirectional and upwards. Transfer of mands is always unidirectional and downwards, with expansion at the local control level. This approach preserves the strict rules of the hierarchy for exact monitoring detection and alarm systems associated with high risk plants. The classification of the two layers of controls is based upon layers of decision making, with respect to the facts that (a) When the decision time es, the making and implementation of a decision cannot be postponed (b) The decisions have uncertainty (c) It will isolate local decisions (. local
畢業(yè)設(shè)計(jì)相關(guān)推薦
鄂ICP備17016276號(hào)-1