Decentralized decentralized distributed system
Publish: 2021-03-29 04:09:44
1.
The 
R9 390 is not bad, but the cost performance is not as high as the current 480 570. In terms of mining, 470 570 580 480 is still the most realistic
2.
First, the conclusion is given. Then, of course, the domestic superconcting quantum cloud platform & mdash& mdash;& ldquo; Wu Yuan & quot; Of course, it is the progress of science and technology
However, it should be noted that this quantum computing cloud platform is the first quantum computing platform made in China, not the world. In fact, it's abroad. There has been research on this aspect for a long time. We started relatively late and are not in the leading position in the world. But on the whole, this is a new technology. No company in the world has really mastered it. Everyone is in the stage of gropingwe can see that the reason why the state and enterprises invest so much money and experience is that those who master the technology first have the core competitiveness, have the right to decide in the field of blue ocean, and have the right to make rules, which is the most critical
therefore, the competition of this technology has just begun, and it is not sure who will win
3.
A 300 qubit computer can hold everything since human civilization, and how much is there in the quantum field is beyond the scope of human cognition. Do you think it's powerful? So Einstein's words are very appropriate, saying that this thing is old and powerful! The reason why this quantum computer is so powerful is precisely because of two characteristics of quantum: one is the superposition of quantum and the other is the entangled state of quantum. How can you hear these two words? They seem very interesting, but all the scientists in the world don't feel painful when they mention these two words! So, listen to me nagging you today{ RRRRR}
imagine! How high is the height, but no matter how high you say, I'm sorry. You're wrong. You can try it with A4 paper! I've folded it several times, but I can't move. If I can continue to fold it for ten times, it's about 10 cm. But when I fold it for 24 times, how high is it? 105 meters, 30 or 40 stories, so high 1, but how high do you fold to 30 times? 7100 km, the ozone layer is dry and broken. If you fold it 50 times, you can go back and forth from Dalian to Jinxing for 110 million times. You can't beat your watch if you walk together
if you fold 90 times, 15 million light-years, 100 times the diameter of the Milky way. If it's 100 times exciting, brothers, 13.7 billion light-years, and the Big Bang is only 13.7 billion years in total. Let's say that on the day of the universe, light began to run. Now, the universe has done you a cool job. But don't forget, it's also multiplied by 0.1 mm in front of him. But look, the 100 power of 2 is ten times larger than this number, and, On the basis of this number, we can turn it back to the power of 300. I can't even imagine how big it is. My brain is aching. That's why I said that since the beginning of human civilization, all observable universes can be saved by this calculator, because it's big enough. You can see a lot of science fiction movies, Like the matrix, he thinks that human beings are likely to live in a huge computer program
4.
5.
On February 8, 2021, the first domestic quantum computer operating system & mdash& mdash;& ldquo; Benyuan Sinan & quot; It was officially released in Hefei, Anhui Province. The system is independently developed by Hefei Benyuan Quantum Computing Technology Co., Ltd., which realizes the systematic management of quantum resources, parallel execution of quantum computing tasks, automatic calibration of quantum chips and other new functions, and helps the efficient and stable operation of quantum computers, marking that the research and development capacity of domestic quantum software has reached the international advanced level
with the advent of the era of quantum computing, & lt; Benyuan Sinan & quot; It can not only make the quantum computer run more efficiently, but also cultivate the user's habit of using the domestic quantum operating system, so that Chinese people can master the real core technology in the era of quantum computing
it is reported that in the next step, the original quantum R & D team will be based on the original quantum computer cluster with completely independent intellectual property rights; Benyuan Sinan & quot; Quantum computer operating system, original quantum cloud platform and rich quantum software and applications will create a perfect and open quantum computing service ecosystem, and work with quantum computing instry chain enterprises to realize the wide application of quantum computing applications
6. In recent years, with the rapid development of geographic information system, more and more application fields are closely related to GIS technology. Because the traffic information system has the characteristics of high precision, complex rules, dynamic, discrete and so on, the original information technology can not fully meet the needs of traffic applications, and with the help of the powerful function of GIS, it can achieve the requirements of the times of traffic information. More and more researchers and developers pay attention to the application of GIS in the field of transportation
Transportation Geographic Information System (TGIS) is a computer software and hardware system for collecting, sorting, storing, managing, comprehensively analyzing and processing spatial information and transportation information. It is the extension of GIS technology in transportation field and the integration of GIS and various transportation information analysis and processing technologies. GIS-T has powerful function of traffic information service and management. It can be used in every link of traffic management. In the field of traffic engineering, GIS technology and methods are used to study traffic planning, traffic construction, traffic management and related problems, which has incomparable advantages compared with other traditional methods
in the 1960s, the U.S. Census Bureau established dime and later tiger data model. At that time, they used one-dimensional linear network based on points and lines to express road system. All kinds of attribute information of point and line are recorded in those attribute tables connected with point and line. For a long time, this model is a mainstream of road traffic system expression model. But with the development of society and economy, the road traffic system becomes more and more complex, and the requirement of traffic geographic information system is higher and higher. GIS-T will face more challenges< The key technology of GIS-T is the combination of GIS and tis. At present, many researchers are committed to the research and development of GIS-T, and many research topics have been generated around GIS-T. different research topics involve different functions of GIS-T. In order to explain in detail, a general framework can be obtained by defining three functional groups: Data Management (realizing data storage and maintenance), data operation (realizing innovation of original data), data analysis or establishing analyzable model. Data storage is the premise of data operation, and data modeling is based on the former two
3.1 database management system
for a long time, transportation departments have to use and maintain a large amount of information. In many cases, multiple transportation information systems coexist in the same department, and each transportation information system can only process a certain kind of data information (such as highway planning network, highway management system and accident information, etc.). The key technology of GIS-T data management system is to store the above different data in a unified data management system by establishing a data model and data exchange framework. Any department can access the data in the system that meets the requirements of its own department, and can analyze and model these data, and then manage and make decisions
3.2 data collaboration
traffic data are generally provided and maintained by multiple organizations, so it is difficult to unify data types and data standards. Each data source may have its own data model. The difference of data models and the diversity of using methods cause great problems to data management and analysis. Due to the errors of data location, topological structure, classification, naming and attribute, linear measurement, the process of unifying data from different sources is complex and the result is uncertain. In order to make GIS technology progress in the field of transportation, we must use data collaboration technology to solve the problem of data unification from three aspects: map matching algorithm, traffic data error model and error propagation (especially one-dimensional data model), data quality standard and data exchange standard
with the more and more extensive application of geographic data, the topic of collaboration has graally become one of the most urgent issues in the field of GIS-T. Data collaboration technology must be applied in the detailed digital Street database, emergency arrangement and scheling system, vehicle navigation system and its (Intelligent Transportation System) parts (including wireless communication between survey users and transportation control center or information service provider)< The collection of real-time GIS-T is a continuous process. In recent years, data operation based on real-time has begun to appear. For example, vehicles with GPS
provide speed, location and other element information to the transportation management center, and the management center will return the forecast information to the vehicles according to the traffic information sent, thus forming a regional congestion management system. Thus, the storage, recovery, processing and analysis of real-time data need faster data access mode, more powerful spatial data fusion technology and dynamic routing algorithm
3.4 huge data set
real world traffic problems involve huge geographic data and complex networks. Geographic Information Science Studies and integrates the rules of geographic visualization and data acquisition, the calculation methods of technology discovery and data acquisition, and promotes the development of GIS-T
e to the different sizes of traffic data sets, the system design needs to be updated frequently. This system design includes the accuracy of information display, optimization of speed, analysis tools in algorithm running time and process, and optimization of network analysis
3.5 distributed computing
the connectivity provided by Internet technology has changed the relationship among computers, application software, data and users. Computer has become a mobile, distributed and ubiquitous entity. GIS application based on Internet is becoming more and more popular (including in the field of transportation). The distributed computing technology based on communication network technology can effectively use local and remote computing resources, and realize the idea of timely application with the help of perfect system resources< The most basic part of GIS is data, and GIS-T is no exception. But for many years, on the one hand, e to the lack of authoritative professional data companies to proce and sell basic geographic data, the required data source is not guaranteed, resulting in a lot of human and material resources spent on the proction of basic data; On the other hand, the existing data is not fully utilized, and the basic data accumulated by various departments are difficult to be shared and utilized e to the disunity of data format and planning, which not only increases the cost, but also prolongs the construction cycle. Therefore, to realize the integration of multi-source data and to solve the integration of multi format data sources is an important topic in the research and development of GIS-T system in recent years. At present, there are three schemes as follows:
(1) according to the format conversion mode: other data formats are converted by a special data conversion program, and then copied to the database or file of the current system
(2) data interoperability mode: This is a specification developed by Open GIS Consortium (OGC). GIS interoperability means that GIS users can obtain the required information transparently on the basis of mutual understanding in the case of heterogeneous databases and distributed computing
(3) direct data access mode: direct access to other software data formats can be realized in one GIS software, and users can use a single GIS software to store multiple data formats< There are three kinds of models in GIS-T: 1) regional model, which represents the phenomenon of continuous change when crossing space; 2) regional model, which represents the phenomenon of continuous change when crossing space; ② Discrete entity model is the abstract expression of discrete entity (point, line or polygon) and its related attributes; ③ The network model represents the abstract expression of the linear network changes embedded in the earth's surface. Due to the characteristics of the transportation system, the data models applied to the transportation system are almost within the scope of the above three models
when expressing the traffic model, we can use many line segments with multiple attributes to represent the road network, use discrete points to represent the landmark features in various road networks, and use linear network algebra to analyze the traffic network. These methods play a certain role in realizing the computer representation of the road traffic system. In the field of transportation, the network model based on the concept of arc and point plays the most important role. In fact, in many transportation applications, only a single network model representing data is needed. Examples of such applications include:
(1) sidewalk and other equipment management systems
(2) real time and offline scheling
(3) network based traffic information system and itinerary planning task< (4) navigation system
(5) real time traffic jam management and accident detection< In the field of transportation, GIS-T is recognized as a pillar instry in the 21st century and an important part of information instry. With the further development of GIS technology research, the existing problems in GIS-T will be graally solved, which will promote the application and development of GIS-T in all aspects, greatly change the traffic situation, drive the rapid development of the whole traffic instry, and become an important driving force to promote economic development.
Transportation Geographic Information System (TGIS) is a computer software and hardware system for collecting, sorting, storing, managing, comprehensively analyzing and processing spatial information and transportation information. It is the extension of GIS technology in transportation field and the integration of GIS and various transportation information analysis and processing technologies. GIS-T has powerful function of traffic information service and management. It can be used in every link of traffic management. In the field of traffic engineering, GIS technology and methods are used to study traffic planning, traffic construction, traffic management and related problems, which has incomparable advantages compared with other traditional methods
in the 1960s, the U.S. Census Bureau established dime and later tiger data model. At that time, they used one-dimensional linear network based on points and lines to express road system. All kinds of attribute information of point and line are recorded in those attribute tables connected with point and line. For a long time, this model is a mainstream of road traffic system expression model. But with the development of society and economy, the road traffic system becomes more and more complex, and the requirement of traffic geographic information system is higher and higher. GIS-T will face more challenges< The key technology of GIS-T is the combination of GIS and tis. At present, many researchers are committed to the research and development of GIS-T, and many research topics have been generated around GIS-T. different research topics involve different functions of GIS-T. In order to explain in detail, a general framework can be obtained by defining three functional groups: Data Management (realizing data storage and maintenance), data operation (realizing innovation of original data), data analysis or establishing analyzable model. Data storage is the premise of data operation, and data modeling is based on the former two
3.1 database management system
for a long time, transportation departments have to use and maintain a large amount of information. In many cases, multiple transportation information systems coexist in the same department, and each transportation information system can only process a certain kind of data information (such as highway planning network, highway management system and accident information, etc.). The key technology of GIS-T data management system is to store the above different data in a unified data management system by establishing a data model and data exchange framework. Any department can access the data in the system that meets the requirements of its own department, and can analyze and model these data, and then manage and make decisions
3.2 data collaboration
traffic data are generally provided and maintained by multiple organizations, so it is difficult to unify data types and data standards. Each data source may have its own data model. The difference of data models and the diversity of using methods cause great problems to data management and analysis. Due to the errors of data location, topological structure, classification, naming and attribute, linear measurement, the process of unifying data from different sources is complex and the result is uncertain. In order to make GIS technology progress in the field of transportation, we must use data collaboration technology to solve the problem of data unification from three aspects: map matching algorithm, traffic data error model and error propagation (especially one-dimensional data model), data quality standard and data exchange standard
with the more and more extensive application of geographic data, the topic of collaboration has graally become one of the most urgent issues in the field of GIS-T. Data collaboration technology must be applied in the detailed digital Street database, emergency arrangement and scheling system, vehicle navigation system and its (Intelligent Transportation System) parts (including wireless communication between survey users and transportation control center or information service provider)< The collection of real-time GIS-T is a continuous process. In recent years, data operation based on real-time has begun to appear. For example, vehicles with GPS
provide speed, location and other element information to the transportation management center, and the management center will return the forecast information to the vehicles according to the traffic information sent, thus forming a regional congestion management system. Thus, the storage, recovery, processing and analysis of real-time data need faster data access mode, more powerful spatial data fusion technology and dynamic routing algorithm
3.4 huge data set
real world traffic problems involve huge geographic data and complex networks. Geographic Information Science Studies and integrates the rules of geographic visualization and data acquisition, the calculation methods of technology discovery and data acquisition, and promotes the development of GIS-T
e to the different sizes of traffic data sets, the system design needs to be updated frequently. This system design includes the accuracy of information display, optimization of speed, analysis tools in algorithm running time and process, and optimization of network analysis
3.5 distributed computing
the connectivity provided by Internet technology has changed the relationship among computers, application software, data and users. Computer has become a mobile, distributed and ubiquitous entity. GIS application based on Internet is becoming more and more popular (including in the field of transportation). The distributed computing technology based on communication network technology can effectively use local and remote computing resources, and realize the idea of timely application with the help of perfect system resources< The most basic part of GIS is data, and GIS-T is no exception. But for many years, on the one hand, e to the lack of authoritative professional data companies to proce and sell basic geographic data, the required data source is not guaranteed, resulting in a lot of human and material resources spent on the proction of basic data; On the other hand, the existing data is not fully utilized, and the basic data accumulated by various departments are difficult to be shared and utilized e to the disunity of data format and planning, which not only increases the cost, but also prolongs the construction cycle. Therefore, to realize the integration of multi-source data and to solve the integration of multi format data sources is an important topic in the research and development of GIS-T system in recent years. At present, there are three schemes as follows:
(1) according to the format conversion mode: other data formats are converted by a special data conversion program, and then copied to the database or file of the current system
(2) data interoperability mode: This is a specification developed by Open GIS Consortium (OGC). GIS interoperability means that GIS users can obtain the required information transparently on the basis of mutual understanding in the case of heterogeneous databases and distributed computing
(3) direct data access mode: direct access to other software data formats can be realized in one GIS software, and users can use a single GIS software to store multiple data formats< There are three kinds of models in GIS-T: 1) regional model, which represents the phenomenon of continuous change when crossing space; 2) regional model, which represents the phenomenon of continuous change when crossing space; ② Discrete entity model is the abstract expression of discrete entity (point, line or polygon) and its related attributes; ③ The network model represents the abstract expression of the linear network changes embedded in the earth's surface. Due to the characteristics of the transportation system, the data models applied to the transportation system are almost within the scope of the above three models
when expressing the traffic model, we can use many line segments with multiple attributes to represent the road network, use discrete points to represent the landmark features in various road networks, and use linear network algebra to analyze the traffic network. These methods play a certain role in realizing the computer representation of the road traffic system. In the field of transportation, the network model based on the concept of arc and point plays the most important role. In fact, in many transportation applications, only a single network model representing data is needed. Examples of such applications include:
(1) sidewalk and other equipment management systems
(2) real time and offline scheling
(3) network based traffic information system and itinerary planning task< (4) navigation system
(5) real time traffic jam management and accident detection< In the field of transportation, GIS-T is recognized as a pillar instry in the 21st century and an important part of information instry. With the further development of GIS technology research, the existing problems in GIS-T will be graally solved, which will promote the application and development of GIS-T in all aspects, greatly change the traffic situation, drive the rapid development of the whole traffic instry, and become an important driving force to promote economic development.
7. UG is the abbreviation of Unigraphics, is a trade name. This is an interactive CAD / CAM (computer aided design and computer aided manufacturing) system, which has powerful functions and can easily realize the construction of various complex entities and modeling. It is mainly based on workstations
CAD is the abbreviation of computer aided design, which is the common name of the instry. It does not include cam (Computer Aided Manufacturing). There are many softwares that can realize CAD functions, including UG, AutoCAD, Cimatron, Pro / Engineer, Solidworks, Kaimu CAD and so on. AutoCAD is another PC based CAD software developed by Autodesk.
CAD is the abbreviation of computer aided design, which is the common name of the instry. It does not include cam (Computer Aided Manufacturing). There are many softwares that can realize CAD functions, including UG, AutoCAD, Cimatron, Pro / Engineer, Solidworks, Kaimu CAD and so on. AutoCAD is another PC based CAD software developed by Autodesk.
8. 3D modeling includes 3D Max, rhino, Maya, SketchUp, etc
9. Building intercom system
Fenglin Boya, the whole development of building intercom system solutions, first-class technology, the latest features, become your right choice www.fl-by.com
Abstract: This paper introces the composition, basic function, principle, core software and hardware technology, development history of building automation system, and briefly introces the related procts, So that readers have a comprehensive understanding of the system, but also for the relevant professional designers to provide a theoretical reference<
key words: basic functions and principles of building automation system, core software and hardware technology
1 Introction
building automation system, also known as building automation system (BAS), is an indispensable part of intelligent building, whose task is to monitor the energy use, environment, traffic and safety facilities in the building In order to provide a safe and reliable, energy-saving and comfortable working or living environment
2 composition and basic functions of building automation system
building equipment automation system usually includes HVAC, water supply and drainage, power supply and distribution, lighting, elevator, fire protection, security and other subsystems. According to China's instry standards, bas can be divided into equipment operation management and monitoring subsystem and fire protection and safety prevention subsystem, as shown in the figure. In general, the two subsystems should be considered together in BAS. If the fire protection and security subsystem is set up independently, the communication with bas monitoring center should also be established, so that when the disaster occurs, the operation right can be transferred according to the agreement, and the integrated coordinated control can be carried out
the basic functions of building equipment automation system can be summarized as follows:
(1) automatically monitor and control the start and stop of various mechanical and electrical equipment, and display or print the current operation status
(2) automatically detect, display and print the operation parameters and their change trend or historical data of various electromechanical equipment
(3) according to the external conditions, environmental factors and load changes, all kinds of equipment can be automatically adjusted to make it always run in the best state
(4) monitor and deal with all kinds of accidents and emergencies in time
(5) realize the unified management and coordinated control of various mechanical and electrical equipment in the building
(6) energy management: the measurement and charging of water, electricity and gas, and the automation of energy management
(7) equipment management: including equipment files, equipment operation reports and equipment maintenance management
3 principle of building automation control system
the building control system is a distributed computer control system based on modern control theory, also known as distributed control systems (DCS). It is characterized by "centralized management and decentralized control", that is, using the microcomputer control device (DDC) distributed in the field controlled equipment to complete the real-time detection and control tasks of controlled equipment, which overcomes the danger brought by computer centralized control, the deficiency of highly centralized control and the limitation of single control function of conventional instruments. The central management computer installed in the central control room has CRT display, printout, rich software management and strong digital communication functions. It can complete the tasks of centralized operation, display, alarm, printing and optimal control. It avoids the shortcomings of the traditional instrument control, such as the difficulty of human-computer connection and the failure of unified management, and ensures that the equipment runs in the best state
here are some concepts related to distributed control system
3. L direct digital control system (DDC)
direct digital control system (DDC) is shown in Figure 2. The computer collects real-time data through analog input channel (AI) and switching input channel (DI), then calculates according to certain rules, finally sends out control signals, and directly controls the proction process through analog output channel (AO) and switching output channel (do). Therefore, DDC system is a closed-loop control system, which is the most common application of computer in instrial proction process
the computer in DDC system directly undertakes the control task, so it requires good real-time performance, high reliability and strong adaptability< The direct digital control system is mainly composed of three parts: process input channel, process control computer and process output channel
the process input channel consists of analog input and digital input. The analog input channel consists of transmitter, sampling switch, amplifier, a / D converter and interface circuit. The function of the transmitter is to convert the non electric signal into standard electrical signal, and to convert the temperature, pressure and flow into 0-10mA or 4-20mA DC electrical signal, which is realized by a / D converter The digital input channel is composed of switch contact, optocoupler and interface circuit. The contact signal reflecting on / off state of proction process is transformed into digital signal and sent to computer through optocoupler and interface circuit
the process control computer directly undertakes the calculation and control tasks. Firstly, it collects various parameter signals of the controlled object through the process input channel, then performs the calculation according to the predetermined control law (such as PID), and then sends the control signal to the controlled object, and then directly controls the control valve and other actuators through the output channel
the process output channel consists of analog output and digital output. The former converts the digital control signal from the computer into analog voltage or current signal, and then drives the control valve and other actuators through the amplifier to control the proction process. This part consists of interface circuit, D / a converter, amplifier and actuator. The latter drives the solenoid valve and relay actuator with the switch signal from the computer through the amplifier, which is composed of interface appliance, optocoupler, amplifier and actuator
3.1.2 basic algorithm of direct digital control system
control according to the proportion (P), integral (I) and differential (d) of deviation is a basic law with mature technology and the most widely used in continuous system. By discretizing PID control law and realizing it on computer, the accumulated mature technology can be easily used, And it can achieve satisfactory results through online tuning when the mathematical model or parameters of the controlled object are not very clear. Therefore, the digital PID algorithm, which discretizes the analog regulation law, has been widely used in the instrial process computer control system and has become the basic algorithm of DDC system
Digital PID control algorithm, the ideal PID formula of analog quantity regulator is
where e (T) - deviation (difference between set value and actual output value)
U (T) - control quantity
KP - proportional amplification coefficient
Ti - integral time constant
td - differential time constant
written in the form of transfer function
in order to realize on computer, It is necessary to transform the continuous differential equation into the discrete difference equation. Let K be the sampling number (k = 0, 1, 2,...), The rectangular method can be used to calculate the proct, and the differential can be replaced by difference
where e (k) - the deviation value obtained by the kth sampling
e (k-1) - the deviation value obtained by the kth sampling
U (k) - the control quantity at the kth time
the smaller the sampling period T in the above formula (compared with the system time constant), the closer the controlled process is to the continuous control process, It is also called "quasi continuous control"< 3.2 architecture of distributed control system
distributed control systems (DCS) emerged and developed rapidly in the mid-1970s. It integrates computer technology, control technology, graphic display technology and communication technology. It can control the equipment scattered in the field, and it is convenient for centralized management and operation, Compared with the previous control system, it not only avoids the shortcomings of single computer centralized control, but also overcomes the shortcomings of human-computer interaction difficulties of conventional instruments
multiple microcomputers in the distributed control system replace the single computer in the centralized control system, which disperses the risk and improves the reliability. Its basic structure and functions are shown in Figure 3. In the figure, the field control station, data acquisition station, engineer station, operator station, monitoring computer and management computer are organically combined through the data communication network to form a hierarchical distributed control system
3.2.1 data communication network of distributed control system
data communication network is the pillar of distributed control system. The structure of the whole distributed control system is essentially a network structure. The field control station, data acquisition station, engineer station, operator station and monitoring computer are all "nodes" in the network, which contain CPU and network interface. They all have their own specific network address (node number) and can send and receive data through the network, Each node in the network is in an equal position, which can share resources and not depend on each other, forming a functional structure with unified command and scattered danger. The network architecture area has great scalability and strong scalability, which can meet the needs of expansion and upgrading of distributed control system, and is very flexible and convenient
(1) the communication network of distributed control system is different from general computer network. Compared with general communication network, it has the following special requirements: (1) it has high reliability and security, and the information transmitted is absolutely accurate and reliable. Therefore, rendancy technology, backup measures and self diagnosis function are often used. For example: the control station adopts double CPU board, double I / 0 board, etc. ② It has good real-time performance. ③ It has strong adaptability to the environment
(2) the network topology of building equipment automation system commonly used are bus network and ring network. In the two structures, any two nodes can communicate directly through the network, and each node is in an equal position
(3) the network communication protocol constitutes the building equipment automation system, and there must be a working language that everyone can accept and abide by to realize the dialogue between each other, which is the data communication protocol standard
the BACnet protocol for building automation control network is composed of physical layer, data link layer, network layer and application layer, or equivalent to the first, second, third and seventh layer protocol of open system interconnection reference model (OSI).
ARCNET is a token bus network with good real-time data transmission rate of 2.5-20bit/s. MS / TP is a master / slave token passing data link layer technology, which allows the use of eia-485 hardware. BACnet realizes the technology of communication between automatic control systems of different manufacturers, that is, the technology of interconnection from one "island" to another< (1) fieldbus overview fieldbus is a digital two-way transmission and multi branch communication network connecting intelligent field devices and automation system. Different fieldbuses follow different protocols and interface standards, which have their own characteristics. Fieldbus technology has the following characteristics: 1) digital signal is used to replace 4-20mA analog signal, which greatly improves the accuracy and reliability of signal conversion, so fieldbus has a high performance price ratio. ② The fieldbus connects the intelligent instruments (intelligent sensors, intelligent actuators) in the field of equipment
Fenglin Boya, the whole development of building intercom system solutions, first-class technology, the latest features, become your right choice www.fl-by.com
Abstract: This paper introces the composition, basic function, principle, core software and hardware technology, development history of building automation system, and briefly introces the related procts, So that readers have a comprehensive understanding of the system, but also for the relevant professional designers to provide a theoretical reference<
key words: basic functions and principles of building automation system, core software and hardware technology
1 Introction
building automation system, also known as building automation system (BAS), is an indispensable part of intelligent building, whose task is to monitor the energy use, environment, traffic and safety facilities in the building In order to provide a safe and reliable, energy-saving and comfortable working or living environment
2 composition and basic functions of building automation system
building equipment automation system usually includes HVAC, water supply and drainage, power supply and distribution, lighting, elevator, fire protection, security and other subsystems. According to China's instry standards, bas can be divided into equipment operation management and monitoring subsystem and fire protection and safety prevention subsystem, as shown in the figure. In general, the two subsystems should be considered together in BAS. If the fire protection and security subsystem is set up independently, the communication with bas monitoring center should also be established, so that when the disaster occurs, the operation right can be transferred according to the agreement, and the integrated coordinated control can be carried out
the basic functions of building equipment automation system can be summarized as follows:
(1) automatically monitor and control the start and stop of various mechanical and electrical equipment, and display or print the current operation status
(2) automatically detect, display and print the operation parameters and their change trend or historical data of various electromechanical equipment
(3) according to the external conditions, environmental factors and load changes, all kinds of equipment can be automatically adjusted to make it always run in the best state
(4) monitor and deal with all kinds of accidents and emergencies in time
(5) realize the unified management and coordinated control of various mechanical and electrical equipment in the building
(6) energy management: the measurement and charging of water, electricity and gas, and the automation of energy management
(7) equipment management: including equipment files, equipment operation reports and equipment maintenance management
3 principle of building automation control system
the building control system is a distributed computer control system based on modern control theory, also known as distributed control systems (DCS). It is characterized by "centralized management and decentralized control", that is, using the microcomputer control device (DDC) distributed in the field controlled equipment to complete the real-time detection and control tasks of controlled equipment, which overcomes the danger brought by computer centralized control, the deficiency of highly centralized control and the limitation of single control function of conventional instruments. The central management computer installed in the central control room has CRT display, printout, rich software management and strong digital communication functions. It can complete the tasks of centralized operation, display, alarm, printing and optimal control. It avoids the shortcomings of the traditional instrument control, such as the difficulty of human-computer connection and the failure of unified management, and ensures that the equipment runs in the best state
here are some concepts related to distributed control system
3. L direct digital control system (DDC)
direct digital control system (DDC) is shown in Figure 2. The computer collects real-time data through analog input channel (AI) and switching input channel (DI), then calculates according to certain rules, finally sends out control signals, and directly controls the proction process through analog output channel (AO) and switching output channel (do). Therefore, DDC system is a closed-loop control system, which is the most common application of computer in instrial proction process
the computer in DDC system directly undertakes the control task, so it requires good real-time performance, high reliability and strong adaptability< The direct digital control system is mainly composed of three parts: process input channel, process control computer and process output channel
the process input channel consists of analog input and digital input. The analog input channel consists of transmitter, sampling switch, amplifier, a / D converter and interface circuit. The function of the transmitter is to convert the non electric signal into standard electrical signal, and to convert the temperature, pressure and flow into 0-10mA or 4-20mA DC electrical signal, which is realized by a / D converter The digital input channel is composed of switch contact, optocoupler and interface circuit. The contact signal reflecting on / off state of proction process is transformed into digital signal and sent to computer through optocoupler and interface circuit
the process control computer directly undertakes the calculation and control tasks. Firstly, it collects various parameter signals of the controlled object through the process input channel, then performs the calculation according to the predetermined control law (such as PID), and then sends the control signal to the controlled object, and then directly controls the control valve and other actuators through the output channel
the process output channel consists of analog output and digital output. The former converts the digital control signal from the computer into analog voltage or current signal, and then drives the control valve and other actuators through the amplifier to control the proction process. This part consists of interface circuit, D / a converter, amplifier and actuator. The latter drives the solenoid valve and relay actuator with the switch signal from the computer through the amplifier, which is composed of interface appliance, optocoupler, amplifier and actuator
3.1.2 basic algorithm of direct digital control system
control according to the proportion (P), integral (I) and differential (d) of deviation is a basic law with mature technology and the most widely used in continuous system. By discretizing PID control law and realizing it on computer, the accumulated mature technology can be easily used, And it can achieve satisfactory results through online tuning when the mathematical model or parameters of the controlled object are not very clear. Therefore, the digital PID algorithm, which discretizes the analog regulation law, has been widely used in the instrial process computer control system and has become the basic algorithm of DDC system
Digital PID control algorithm, the ideal PID formula of analog quantity regulator is
where e (T) - deviation (difference between set value and actual output value)
U (T) - control quantity
KP - proportional amplification coefficient
Ti - integral time constant
td - differential time constant
written in the form of transfer function
in order to realize on computer, It is necessary to transform the continuous differential equation into the discrete difference equation. Let K be the sampling number (k = 0, 1, 2,...), The rectangular method can be used to calculate the proct, and the differential can be replaced by difference
where e (k) - the deviation value obtained by the kth sampling
e (k-1) - the deviation value obtained by the kth sampling
U (k) - the control quantity at the kth time
the smaller the sampling period T in the above formula (compared with the system time constant), the closer the controlled process is to the continuous control process, It is also called "quasi continuous control"< 3.2 architecture of distributed control system
distributed control systems (DCS) emerged and developed rapidly in the mid-1970s. It integrates computer technology, control technology, graphic display technology and communication technology. It can control the equipment scattered in the field, and it is convenient for centralized management and operation, Compared with the previous control system, it not only avoids the shortcomings of single computer centralized control, but also overcomes the shortcomings of human-computer interaction difficulties of conventional instruments
multiple microcomputers in the distributed control system replace the single computer in the centralized control system, which disperses the risk and improves the reliability. Its basic structure and functions are shown in Figure 3. In the figure, the field control station, data acquisition station, engineer station, operator station, monitoring computer and management computer are organically combined through the data communication network to form a hierarchical distributed control system
3.2.1 data communication network of distributed control system
data communication network is the pillar of distributed control system. The structure of the whole distributed control system is essentially a network structure. The field control station, data acquisition station, engineer station, operator station and monitoring computer are all "nodes" in the network, which contain CPU and network interface. They all have their own specific network address (node number) and can send and receive data through the network, Each node in the network is in an equal position, which can share resources and not depend on each other, forming a functional structure with unified command and scattered danger. The network architecture area has great scalability and strong scalability, which can meet the needs of expansion and upgrading of distributed control system, and is very flexible and convenient
(1) the communication network of distributed control system is different from general computer network. Compared with general communication network, it has the following special requirements: (1) it has high reliability and security, and the information transmitted is absolutely accurate and reliable. Therefore, rendancy technology, backup measures and self diagnosis function are often used. For example: the control station adopts double CPU board, double I / 0 board, etc. ② It has good real-time performance. ③ It has strong adaptability to the environment
(2) the network topology of building equipment automation system commonly used are bus network and ring network. In the two structures, any two nodes can communicate directly through the network, and each node is in an equal position
(3) the network communication protocol constitutes the building equipment automation system, and there must be a working language that everyone can accept and abide by to realize the dialogue between each other, which is the data communication protocol standard
the BACnet protocol for building automation control network is composed of physical layer, data link layer, network layer and application layer, or equivalent to the first, second, third and seventh layer protocol of open system interconnection reference model (OSI).
ARCNET is a token bus network with good real-time data transmission rate of 2.5-20bit/s. MS / TP is a master / slave token passing data link layer technology, which allows the use of eia-485 hardware. BACnet realizes the technology of communication between automatic control systems of different manufacturers, that is, the technology of interconnection from one "island" to another< (1) fieldbus overview fieldbus is a digital two-way transmission and multi branch communication network connecting intelligent field devices and automation system. Different fieldbuses follow different protocols and interface standards, which have their own characteristics. Fieldbus technology has the following characteristics: 1) digital signal is used to replace 4-20mA analog signal, which greatly improves the accuracy and reliability of signal conversion, so fieldbus has a high performance price ratio. ② The fieldbus connects the intelligent instruments (intelligent sensors, intelligent actuators) in the field of equipment
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