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. Khasm, MSc
Indexing term : Hazards, Design, Plant condition monitoring
Abstract: A complete system for fire detection and alarm monitoring has been propod for complex plants. The system us multiple single chip architecture attached to a party line. The control algorithm is bad on a two-level hierarchy of decision making, thus the comple
xity 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 Introduction
Regulatory requirements for most high risk plants and buildings mandate the installation of fire detection and warning systems for all nsitive areas of the plant or the building. Most fire codes state the requirement for monitoring and control specifically related to a type of a plant or building such as chemical plants, petroleum, nuclear plants, residential high-ris etc. A general conclusion of the codes can be specified as the following requirements :
(a) The source of all detector signals should be exactly identifiable by the central station
(b) An extra path of communication between the central station and all local controllers
(c) Direct means of control of alarm and central equipment by the central station
(d) Means of communication between the central station and the fire department
抚平皱纹(e) Availability of emergency power supply. The codes usually also specify the types and frequency of tests for all equipment.
A fire detection and alarm system is a combination of devices designed to signal an alarm in ca of a fire. The system may also accomplish fan control, fire door hold or relea, elevator recall, emergency lighting control and other emergency functions. The additional functions supplement the basic system which consists of detection and alarm devices and central control unit.
Technology has an influence on system architecture. When technology changes, the arch
itecture has to be revid to take advantage of the changes. In recent years, VLSI technology has been advancing at an exponential rate. First NMOS and, in the last year or two, CMOS chips have been produced with the same packing density with more gates per chip yet at a lower power consumption than NMOS. Surely this change in technology must affect our design of hardware at both the chip and the system level. At the chip level, single chips are now being produced which are equivalent to board levels of only the previous year or two. The chips have 天秤女和天蝎男microprocessor, memory in RAM and ROM, IO Ports both rial and parallel, A/D timer, flags and other functions on chip. At the system level, the new chips make new architectures possible. The 银杏叶胶囊说明书objective of this paper is to show how technology can influence system architecture in the field of fire control. The new high density single chip microcontrollers are incorporated in the范冰冰奥斯卡 design of a large scale system and yet we obtain a smaller system with a better performance. In terms of fire detection and alarm monitoring, this is reflected directly in the local station hardware, becau of their remoteness and正直的反义词 power supply requirements. A complete local station can be designed around a single CMOS chip with power consumption of a few m
W depending on system operation.zqq This approach reduces the cost and complexity of design, implementation and maintenance and provides easily两心相依 expandable and portable 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 u 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 becomes critical, for equipment and evacuation of personnel. Here, we propo a central control and distributed control/detection/monitoring with adequate communication, where u is made of single-chip microcontrollers in the local stations, thus improving controllability and obrvability 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 bad on detecting
the byproduct of a combustion. Smoke detectors, of both ionization and optical types, are the most commonly ud
detector devices. When a typical detector of this type enters the alarm state its current consumption increas
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 tho
given in Table 1. The more nsitive the detector, the more susceptible it is to fal alarms. In order to control the detector precily, either of the following methods is ud: a coincidence technique can be built into the detector, or a filtering technique such that a logic circuit 固一世之雄也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 ud for sleeping areas, infrared or ultraviolet radiation are ud when flammable liquids are being handled, heat detectors are ud for fire suppression or extinguishing systems. In general, life and property protection have different approaches.
