1、 PDF外文：http:/ 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
2、 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 giv
3、en 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 incorpor
4、ated 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 requi
5、rements for most high risk plants and buildings mandate the installation of fire detection and warning systems for all sensitive 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 ch
6、emical plants, petroleum, nuclear plants, residential high-rises etc. A general conclusion of these 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 centr
7、al 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 (e) Availability of emergency power supply. The codes usually also specify the types and frequency of
8、tests for all equipment. A fire detection and alarm system is a combination of devices designed to signal an alarm in case of a fire. The system may also accomplish fan control, fire door hold or release, elevator recall, emergency lighting control and other emergency functions. These additional fun
9、ctions 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 architecture has to be revised to take advantage of these changes. In recent years, VLSI technology has be
10、en 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
11、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. These chips have microprocessor, memory in RAM and ROM, IO Ports both serial and parallel, A/D timer, flags and other functions on chip. At the system level, th
12、e new chips make new architectures possible. The 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 design of a large scale system and yet we obtain a smalle
13、r system with a better performance. In terms of fire detection and alarm monitoring, this is reflected directly in the local station hardware, because of their remoteness and power supply requirements. A complete local station can be designed around a single CMOS chip with power consumption of a few
14、 m W depending on system operation. This approach reduces the cost and complexity of design, implementation and maintenance and provides easily expandable and portable design. This implementation was not possible with old technology. Most of fire detection/monitoring systems available are tailored t
15、owards 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 becomes critical, for equi
16、pment and evacuation of personnel. Here, we propose a central control and distributed control/detection/monitoring with adequate communication, where use is made of single-chip microcontrollers in the local stations, thus improving controllability and observability of the monitoring process. 2 Detec
17、tion 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
18、 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
