发布时间 : 星期四 文章基于单片机的火灾探测和监控系统大学毕业论文外文文献翻译及原文更新完毕开始阅读165a969abdeb19e8b8f67c1cfad6195f312be8f8
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翻译日期： 2017.02.14
外文文献原稿和译文
原 稿
Multiple single-chip microcomputer approach to
fire detection and monitoring system
A.J. AI-Khalili, MSc, PhD D. AI-Khalili, MSc, PhD M.S. Khassem, MSc
Indexing term : Hazards, Design, Plant condition monitoring
Abstract: A complete system for fire detection and alarm monitoring has been proposed for complex plants. The system uses multiple single chip architecture attached to a party line. The control algorithm is based on a two-level hierarchy of decision making, thus the complexity is distributed. A complete circuit diagram is given for the local and the central station with requirements for the software structure. The design is kept in general form such that it can be adapted to a multitude of plant configurations. It is particularly shown how new developments in technology, especially CMOS single chip devices, are incorporated in the system design to reduce the complexity of the overall hardware, e.g. by decomposing the system such that lower levels of hierarchy are able to have some autonomy in decision making, and thus a more complex decision is solved in a simple distributed method.
1 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 combustion. Smoke detectors, of both ionization and optical types, are the most commonly 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 becomes 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 communication or printers that record time, date, location and other information required by the standard code of practice for fire protection for complex plants. Heaviside [4] has an excellent
review of all types of detectors and extinguisher systems.
1.1 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 communication 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 commands. This is shown in Fig. 1 where at level 1 is the central station microcomputer 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 microcomputer. Transfer of status is always unidirectional and upwards. Transfer of commands 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 comes, the making and implementation of a decision cannot be postponed
(b) The decisions have uncertainty
(c) It will isolate local decisions (e.g. locally we might have an alarm although there may be a fault with the system)
2 General hardware
I :Fig. 2 depicts our design in the simplest of forms. The system uses an open