Requirements for CAD technical means. SAD technical support structure

SAD technical support (CAP) includes a computing complex (VC) based on high-performance computer equipment With a large volume of operational and external memory, a wide range of peripheral devices to ensure the dialogue mode, the release of textual and drawing documentation and the creation of full databases.

It is advisable to create complex CAD on the basis of a two-level hierarchical structure with medium and high performance computers at the top level and the network of terminal stations at the lower level.

The choice of typical VC for top level is made depending on the complexity of the design object, which is determined according to the state standards in the number of components.

For the top level of the CAD, there is a release of various modifications of VC with uniform versions of operating systems (OS). The composition of typical VCs should include an OS for processing graphic information, special graphic processors, graphic peripheral devices.

Over the decades of its development, the technical means of CAD passed several stages, largely related to the change of generations of computer and improving the peripheral devices. Basic computers of the first generations of CAD RES - automated workplace (AWT) - based on universal second-class computers and mini-computer with an extended set of peripheral I / O devices of graphic information (AWP based on computer IBM-360 and PDP-11 abroad, AWP based on BESM-6, World, EU EUM , CM computer, "Electronics" in our country).

A characteristic feature of the development of technical means of these generations was the desire to bring the most appointment of AWP to the RES designer using CAD. At the same time, the contradiction between the requirement of relatively low cost, the dimensions and the need for the preservation of high technical parameters of basic computers due to the complexity of the solvable CAD tasks led to the creation of powerful decentralized computer systems united by local computing networks (LAN).

To date, there has been a steadily growing market for the sale of hardware and software in the CAD region, which developed its own requirements for the basic computer, peripheral devices and LAN. As reference basic computers located directly on the tables of RES designers, there are already long-term workstations (PC), associated LANs and other computers.

The PCs have significant differences from personal computers (PCs), since the requirements for PC are formed by the market in the field of CAD, and the requirements for PC are largely the market in the field of office equipment, household appliances, communications and communications. The RS developed independently of the PC, however, the cheapening of the PC elementary base and increasing the requirements for the technical characteristics of the PC led to the fact that the most powerful PC models have entered the CAD market, competing with inexpensive RS.

The features of the architecture and technical characteristics of the PC in terms of their use as basic computing systems in the RES system are most clearly manifested when compared with PCs.

1. The computing core of most PC is the RISC processor, i.e. A processor with a reduced set of commands and increased speed - most of its commands are performed in one period of the clock frequency generator, synchronizing the operation of such a microprocessor (MP). Most PCs have a MP computing kernel with a complex set of commands (CISC processor), which each command is performed in several frequency generator clocks. In this case, relatively lower PC performance is compensated by simpler software and compatibility with earlier PC models.

2. All modern PCs have a large amount of operational storage device (RAM) and operate under the control of complex multitasking operating systems with appropriate hardware support. Most of the PC has a slightly smaller volume of RAM and operates under the control of simpler-planned OS type MS-DOS, although it has a hardware support for OS multitasking. This feature of the PC is due to the complexity of tasks and hierarchy of CAD packages.

3. The presence in PC powerful graphics processors with support for high-speed and high-quality graphics with a resolution of at least 1000x1000 and a color palette to 1.5 million color shades. Most PCs use less high-quality VGA, SVGA standard graphics. This feature of the PC is due to the fact that most CAD tasks require high-quality graphical input / output of information.

4. In the base PC kit, high-speed communication equipment with a standard LAN is defined with a network adapter. In the base kit, the PC is usually not provided for the presence of a network adapter. Such a feature of PC is due to the fact that PC cannot work effectively offline mode, without interaction with other PC and computer types via LAN. PC is designed as an autonomous device, therefore, even when combining PCs into a local network, most of the operations with PC information conducts autonomously. The structural circuit of a typical PC with peripheral devices connected to it is shown in Fig. 5.4.

Fig. 5.4. Workstation architecture

Basic set PC components make up:

o System fee containing a RISC processor with a hardware-realized floating point arithmetic solution (SAPT), operational and constant storage devices (RAM and ROM) and, as a rule, a graphic adapter with a monitor connected to it;

o Communication cards with peripheral devices that make up an input / output subsystem with a keyboard, a mouse type manipulator, sometimes with an automatic scanner, a graph-resistant or laser print;

o Communication fees with external storage devices (waving), network adapter board

5. The basis of the system board is the basic MP, which carries out arithmetic and logical operations, as well as the PC control. On a single crystal of modern RISC-MP, an integer processor is located, often a co-point arithmetic coprocessor, and sometimes a graphics processor for image processing (from hundreds of thousands of up to millions of transistors on one crystal). In some inexpensive variants of the base computers with PC-based MPs with a complex set of commands.

PC and PCs are the lower level of CAD technical means directly accessible RES designers using CAD. Part of the tasks in the CADR requires higher performance, which is achieved by using the computer of other classes and their complexation along with PC and PCs based on the LAN.

Control questions and exercises

1. What are the requirements for maintenance of CAD?

2. What is "Mainframe"?

3. How is the data transfer medium?

4. What is the data transmission channel?

5. Name the methods of separating the data line.

6. Name the options for the topology of local computing networks.

7. What is called server?

8. Name the varieties of servers.

9. How is the transmission of information in network switches and packet switching networks?

10. What is a reference relationship model open Systems (EMVOS)?

11. Tell me about the levels of Emvos.

12. What is called a local computing network (LAN)?

13. What is a workstation (PC)?

14. What is the difference between PC from a personal computer?

15. What is included in the RS architecture?

6. Lecture: SAD technical means and their development (continued)

SAD high-performance technical means are given. A computer architecture is considered depending on the data processing sequence. Compound classes are represented depending on the multiplicity / solitude of command streams and data (OKD, OKMD, ICMD). The main purpose of the lecture is to give a deeper knowledge of technical support of the CAD: EMM architecture depending on the data processing sequence and computer classes depending on the multiplicity / single command streams and data

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operational memory Personal computer

Introduction

2.1 Personal computers

2.2 Workstations

2.3 servers

2.4 Mainframe

2.5 cluster

2.6 supercomputers

Conclusion

Bibliography

Introduction

The traditional form of using a computer concentrated in the computing center and operating only in batch modeis not suitable for modern CAD. A computer will only then become an effective regularly used design tool when the engineer will be able to quickly access the machine and also to quickly receive the results of the solution. Therefore, a group of external I / O devices must be developed in the TC complex. At the same time, the effective interaction of the engineer with a computer will be ensured only if the form is convenient for a person input and displayed information and does not necessarily manually perform burdensome and fragmented errors to coding or decomphering messages. Depending on the nature of the tasks being solved, there may be tables, drawings, graphics, text messages, and the like.

Thus, the first of the claims specified at the beginning of the head technical means CAPR determines the inclusion in the complex TC as a standard set of external devices of the computer and additional devices Operational I / O information, including graphical form. This set of external devices is installed in the project unit indoor and is called an automated workplace (AWA) of the designer

The composition of AD depends on the nature of the tasks solved in the project division. The AWS includes the input and output devices on the punctuent; autonomous input devices with performance perfocar or punched; keyboard device for exchanging information between the operator and computer short messages; Memory devices on magnetic disks (NMD) and magnetic tape (NML); Video monitor or graphic display; Grafopostroiler (plotter); graphic information encoder (coordinate reader) or scanner; Printer, modem or fax modem. The presence in one CAPR of many AWP, the possibilities of simultaneous work on the equipment of ATs of several users and the placement of arm in the territories of the design divisions dictate the need to hierarchical construction of the TC complex with the allocation of at least two levels of computers. At the highest level there is one or more computers of great performance. These computers constitute a central computing complex (FAC), designed to solve complex design tasks that require large amounts of machine time and memory. At the lowest level are the mini-computers (terminal computers). Mini-computers in AWS manages the operation of a set of external devices, the exchange of information between AWP and CEO; Decides relatively uncomplicated on the cost of machine time and memory design tasks.

1. Basic Requirements for CAD technical means

The following requirements are presented to the technical support of the CADR:

ease of use of engineers-designers, the possibility of operational interaction of engineers with computers;

sufficient performance and amount of ECM RAM to solve problems of all design stages for an acceptable time;

the ability to simultaneously work with the technical means of the required number of users for the effective activity of the entire developer team;

openness of a complex of technical means for expanding and modernizing the system as the development and development of equipment improves;

high reliability, acceptable cost, etc.

The satisfaction of the listed requirements is possible only in the conditions of technical support in the form of a specialized Sun, which admits functioning in several modes. Such technical support is called the CAD technical equipment complex (TC complex).

2. Types of computing machines and systems

Computers (computers) and computing systems (Sun) are customary to classify for a number of features. Depending on the performance and cost of computing equipment, several types of computer and aircraft are distinguished, and different generations of computing equipment had its own types of type. So, until the mid-80s of the last century, a computer was divided on a micro-computer mini-computer, a large computer (high performance computers) and super-computer. Currently, the computer and aircraft are subdivided into personal computers, workstations, servers, mainframes, clusters and supercomputers.

Personal computers (PCs), workstations and servers are the greatest distribution in CAD.

2.1 Personal computers

The first personal computers appeared in the early 80s of the last century as a result of a mini-computer transformation into relatively cheap desktop systems for individual use, thanks to the development of the elemental base of computing equipment, which led to the creation of large (bis) and super-high (SBI) integrated circuits.

A constructive personal computer (PC) consists of a housing in which the motherboard is placed; Video adapter (video card); Drives - CD ROM, hard drives and flexible (NGMD) magnetic disks; Power Supply; Speaker. The PC has backup slots (expansion slots) for possible printed circuit boards (cards) expansion - network controller, modem, other additional devices. The PC also includes external (with respect to the PC) device. As a rule, their number includes the keyboard, mouse, monitor. In fig. 1 shows a typical block diagram of PC.

Figure 1. Simplified typical block diagram of personal computer

The motherboard is also called a motherboard. Motherboards produce a large number of companies. On the motherboard There are connectors for inserting a processor and RAM modules. The interface between the processor and other devices is carried out using the help and chipset (chipset) - the set of special microcircuits installed on the motherboard, the so-called northern and southern bridges. To connect the CPU to the North Bridge (system controller) use the system bus (FSB - FrontsideBus). The system bus exchanges between the processor and the second-level cache and through the North Bridge with rAM. As a tire for connecting a graphics controller on modern motherboards, the PCI Express bus is used.

The southern bridge (peripheral controller) contains peripheral device controllers (hard disk, Ethernet, audio), PCI tire controllers, PCI-ExpressIUSB for connecting peripherals, as well as tire controllers to which devices that do not require high bandwidth are connected. Interface with external drives (Winchester, Magnetic discs, CD-ROM) is performed through drive controllers. Usually controllers are built into one of the chips and are located on the motherboard, and the drives themselves are connected to the board using the connectors available on it. Currently use IDE (IntegratedDriveElectronics) or EIDE (EnhanceDDRONICS), which allows you to connect to one controller to four devices. If you need to increase the data transfer rate (for example, when using a PC as a file server) use sCSI interface (SmallcomputersystemInterface). It allows you to connect to one controller to eight devices, the data transfer rate reaches 80 MB / s. To connect the SCSI bus to the PCI requires a special SCSI adapter.

The video card includes a video memory and a video processor used to unload a central processor when performing certain graphic operations and decoding data, for example, when entering from the camcorder. BIOS (BasicInput / OutputSystem) is also located on the motherboard. This unit serves as storing the PC configuration parameters, hardware drivers and POST programs, which, when you turn on the computer, checks the performance of its devices.

2.2 Workstations

Workstations are computing systems focused on solving problems in certain applications, primarily in automated design systems (CAPR). Computers in CAPR are focused on solving complex design tasks, which causes increased speed and amount of memory, as well as advanced handling and visualization of graphic information of workstations compared to personal computers. Therefore, usually workstations have a more complex structure and more expensive devices than PC.

Structure of the workstation:

The motherboard is exactly in it and is placed processor, memory chips, controllers and data bus.

The central processor - the overall speed of all processes depends on it. The power of this device is determined by its tactile frequency than it is higher - the device is faster. The processor is the main element in all processes that occur between workstations in computer network. Connecting several devices, it is desirable that they have processors of the same power, otherwise on more powerful computers, the speed of work will decrease due to the weak PC.

Memory - for normal functioning local network Servers and workstations must have a large memory stock. In order to store data, exchange them and accommodate the software required for the network, workstations are usually several memory sources. Many modern PCs, with completed RAM, refer to virtual pods. For a long time to use virtual memory at office workstations is not advocated, with the help of network service, increase the volume of operational memory stocks.

Network adapter - Connect computers to the local network without a network adapter is not possible, it allows you to turn a computer from a regular device to the workstation. Maintenance of networks allows you to connect with a network adapter to one chain more than a hundred PC. This is a miniprocessor that opens computers. working Group Access to the common database.

Differences of personal computers from the workstation:

Price - Most PCs for business are cheaper than the workstation.

Performance - PC has enough power to solve most tasks, such as email, web surfing and text processing. While the workstation has a big power - it can work with CAD systems, programs for creating animation, analysis of data and photorealistic visualizations, creating and processing video and audio.

Reliability - the requirements for the operation of the components of the workstation are much higher than PC. Each part (motherboard, processor, RAM, discs, video cards, etc.) is made with understanding that it will work throughout the day. In many cases, workstations remain included and work on projects even when all people diverge home. They leave them to work for the night to handle large databases, creating an animation.

2.3 servers

In computing networks, performing functions related to the maintenance of all network nodes is assigned to the servers. The server is a computer that is designed to solve certain tasks for executing program codes, storing information, user maintenance and databases. The server provides maximum security and security of tasks, as well as their safety. The server is used to store files and Internet user websites (hosting), response to requests and issuing the requested information, processing and executing scripts on websites, working with a database and a large number of users. Control over the operation of the server is assigned to the system administrator.

The server does not have to be intended to work with the Internet. Most often, it is used in companies to ensure the local network and storage of clients, workers, products, and also to access the Internet. The system administrator using the server can receive information about all the local network computers, prohibit or allow access. In most cases, the server is not an ordinary personal computer. As a rule, it is a workstation made in the form of a mini-tower, although there are various configurations depending on the specialization. Servers contain one or more high-performance processors, a large amount of RAM, RAID arrays of hard drives, power supplies with the possibility of offline operation in the event of power failure. The server enclosures have increased protection against dust and a powerful cooling system, as well as a random shutdown protection.

According to the functional purpose, the files file, databases, switching, applied, postal, and the like are distinguished. Servers tend to have greater speed, reliability and in many cases increased memory capacity compared to computers in client nodes.

2.4 Mainframe

Mainframes are called large computer. High performance and greater memory capacity provide solutions to complex problems, allow you to use such computers as the central node of the aircraft, managing the work of many simple terminals. The architectural planned inframes are multiprocessor systems containing one or more central and peripheral processors with shared memory, interconnected by high-speed data triggers. In this case, the main computational load falls on central processors, and peripheral processors provide work with a wide range of peripheral devices. IBM company actively supports the transition to large corporate information systems To use mainforms in the quality of data centers instead of a large number of distributed servers.

2.5 cluster

Cluster is a distributed computers system that is functioning as one system with shared resources. The main goal that caused the appearance of clusters is to preserve the operation of the aircraft by the redistribution of the load upon failure of the part of the resources. In addition, clustering is one of the ways to increase the performance of the aircraft by sharing Many computers. Clusters allow you to increase computing power, because it is easily scalable.

Typically distinguish the following main types of clusters:

failover clusters (HIG-AvailabilityClusters, Ha, high availability clusters),

load balancing clusters (LoadBalancingClusters),

computing clusters (High Performance Computing Clusters, HPC),

distributed computing systems.

2.6 supercomputers

Computers characterized the greatest values Performance and prices among other types of computer and sun, are classified as supercomputers. It is believed that super-computer is computers with maximum performance. However, the rapid development of the computer industry makes this concept very and very relative: the fact that ten years ago it was possible to call a supercomputer, today this definition is no longer falling. The performance of the first super-computer of the early 70s was comparable to the performance of modern PCs based on traditional Pentium processors. According to today's standards, neither the others do not belong to the supercomputers. In any computer, all major parameters are interconnected. It is difficult to imagine a universal computer, having high speed and meager RAM or a huge RAM and a small amount of disks. Hence the simple conclusion: Super-computer is a computer that has not only maximum performance, but also the maximum amount of operational and disk memory in a set with specialized software, with which this monster can be effectively used. As a rule, modern supercomputers are a large number of high-performance server computers connected to another local high-speed highway to achieve maximum performance As part of the parallelization approach of the computing task.

Cray-1 is the first supercomputer created in 1976 by Cray Research, founded by the "Father Supercomputers" by Seymour Cher, after his departure from CDC. Peak Cray-1 performance was 133 mflops. For comparison, the current number 1 in the top 500 rating of supercomputers, Tianhe-2, has a computing power of 33.86 PFLS. The computer was purchased by the national meteorological service (so the US residents are obliged by the weather forecast from 1977 to 1989 in this car).

Twice a year, experts from the National Laureren's Laboratory in Berkeley and the University of Tennessee publish the Top-500, which offer a list of the most productive supercomputers of the world.

10. CRAY CS-STORM

Location: United States.

Productivity: 3,57Petaflops.

Theoretical performance maximum: 6.13 Petaflops.

Power: 1.4 MW.

9. VULCAN - BLUE GENE / Q.

Location: USA.

Performance: 4.29 Petaflops.

Theoretical performance maximum: 5.03 Petaflops.

Power: 1.9mV.

8. JUQUEEN - BLUE GENE / Q.

Location: Germany

Productivity: 5Petaflops.

Theoretical performance maximum: 5.87 Petaflops.

Power: 2.3 MW.

7. Stampede - Poweredge C8220.

Location: USA.

Productivity: 5.16 Petaflops.

Theoretical performance maximum: 8.52 Petaflops.

Power: 4.5 MW.

6. PIZ DAINT - CRAY XC30.

Location: Switzerland.

Productivity: 6.27 Petaflops.

Theoretical Maximum Performance: 7.78 Petaflops.

Power: 2.3 MW.

5. MIRA - BLUE GENE / Q.

Location: USA.

Productivity: 8.56 Petaflops.

Theoretical performance maximum: 10.06 Petaflops.

Power: 3.9 MW.

Location: Japan.

Productivity: 10.51 Petaflops.

Theoretical performance maximum: 11.28 Petaflops.

Power: 12.6 MW.

3. SEQUOIA - BLUE GENE / Q.

Location: USA.

Productivity: 17,17 Petaflops.

Theoretical Maximum Performance: 20.13 Petaflops.

Power: 7.8 MW.

2. Titan - Cray XK7.

Location: USA.

Productivity: 17,59 Petaflops.

Theoretical performance maximum: 27,11 Petaflops.

Power: 8.2 MW.

1. Tianhe-2 / Milky Way-2.

Location: China.

Productivity: 33.86Petaflops.

Theoretical performance maximum: 54.9 Petaflops.

Power: 17.6 MW.

3. Architecture of computing systems

The main difference of the aircraft from the computers is the presence of several computers in their structures (computers or processors). Therefore, they are capable of performing parallel calculations. Since the sun appeared as parallel systems, then consider the classification of architectures from this point of view. Such a classification of architectures was proposed by M. Flynn in the early 60s. Its founded two possible views of the parallelism: the independence of the threads of tasks (commands) existing in the system, and independence (non-binding) of the data processed in each stream. According to this classification, there are four main architectures of the Sun:

single Command Flow - Single Data Stream (OKD), In English Abbreviation SingleInstructionSingledata, SISD - Single Instructions Stream - Single Data Flow;

single command stream - multiple data stream (OKMD), or SingleInstructionMultiPledata, SIMD - single instruction flow - single data flow;

multiple command stream - single data stream (ICD), or multipleInstructionSingledata, MISD - multiple instruction flow - multiple data stream;

multiple command stream - multiple data stream (MKMD), or MultiPleInstructionMultiPleData, MIMD -Met Power Instructions - Multiple Data Flow.

The architecture of the OKD covers all single-processor and single-hour variants of systems, that is, systems with one calculator. All computer classical structure falls into this class. Here, the parallelism of calculations is ensured by combining operations to perform individual blocks by Allu, as well as the parallel operation of the I / O devices and processor. The laws of the organization of the computing process in these structures are quite well studied. The OKMD architecture involves the creation of vector or matrix structures. Systems of this type are usually built as uniform: processor elements that are logged in, identical, and all of them are managed by the same sequence of commands. However, each processor processes its data stream. Under this scheme, the tasks of processing matrices or vectors (arrays), the problem of solving linear and nonlinear, algebraic and differential equations, the tasks of the field theory, etc. In the structures of this architecture, it is desirable to ensure compounds between processors that are relevant to realized mathematical dependencies. As a rule, these relationships resemble a matrix in which each processor element is associated with neighboring. A vectorial or matrix type of calculation is a necessary attribute of any super computer.

Conclusion

Computing systems, as powerful tools for handling users, are widely used not only autonomously, but also in computer networks as servers. With increasing sizes of networks and their development, the density of information flows increases, the load on the access to network resources and to the task processing tools. The range of tasks, solved by servers, is constantly expanding, becomes diverse and complex. The higher the network rank, the more specialized they become. Network administrators must constantly increase their power and quantity, optimizing network characteristics for increasing user requests.

Managing computing processes in the aircraft carry out operating systems that are part of the overall software. The OS includes both centralized resource management programs and autonomous use programs of computing modules. The last condition is necessary, since the Sun is usually provided for higher reliability of operation, for example, the requirement for maintaining performance if there is at least one serviceable module in it.

The requirement to increase productivity also implies the ability to parallel and even autonomous work Modules when processing individual tasks or task packages. Depending on the structural organization of the Sun, you can identify some features of building their operating systems. Operating systems for multi-milk Sun are simpler. Usually they are created as a superstructure of autonomous OS individual computers, since each computer has a large autonomy to use resources (its operational and external memory, its separate composition of external devices, etc.). They are widely used by the software methods of the local (within the computing center) and remote (network processing) of the complexation.

Modern personal IWM RS-compatible computers are the most widely used type of computers, their power is constantly increasing, and the scope expands. These computers can be combined on the network, which allows dozens and hundreds of users to easily share information and at the same time gain access to shared databases. Funds email Allow users using a regular telephone network to send text and fax messages to other cities and countries and receive information from large data banks. The global electronic communication system InTERNE provides for an extremely low price the possibility of prompt information from all parts of the globe, provides the possibilities of voice and facsimile, facilitates the creation inside corporate networks Information transfer for firms with branches in different cities and countries.

However, the possibilities of the IWM of RS-compatible personal computers for processing information are still limited, and not in all situations their use is justified.

Bibliography

1. V.N. Datsyuk, A.A. Bukatov, A.I. Slagly. Toolkit At the rate of "multiprocessor systems and parallel programming" / Southern Federal University. Center for high-performance computing.

2. Types of computing machines and systems / biology.

3. Automation of the design of systems and controls / Moscow State University of Press.

4. Technical support of automated systems / biology.

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2.1. Technical and Software

Technical support - This is a complex of technical means, with which the collection, processing, storage, conversion and transmission of data associated with the design object is carried out.

The basis of technical support is the means of computing equipment and, first of all, this is a personal computer.

The standard computer configuration is generally well known (see Fig. 2.1):

· a system unit consisting of a processor, operative to the power supply, power supply, hard drive, data fields, ports connecting peripheral devices;

· keyboard for entering information;

· monitor to display information;

· mouse for the convenience of the "Man-Computer" dialogue.

Fig. 2.1. Personal Computer Standard Configuration

The concept of peripheral devices includes a wide range of technical means. First of all, these are tools for collecting and processing data for design. These include electronic geodetic equipment (tachometers, systems satellite navigation, Laser scanners, etc.), which or works directly under the control of computers, or transmits the data of the measurement of computer files. More information about the technical means of engineering surveys is set forth in Ch. four.

If the initial information about the projected road is presented in the form of topographic plans, then to convert information from paper species to electronic apply scanners(see Fig.2.2, a) . Scanners are rolled or tablet. The accuracy of the recent scanning is significantly higher and can reach 12000 DPI (DOTS PER INCH - dots per inch). When it comes to the design of complex technical objects, the engineering scanners of the large format A 0 (A 1) are used.

Day off graphic information About the design object (drawings) is also printed on plotters of a large format. According to the method of filing paper plotterslike scanners, there are rolled (Fig.2.2, b) or tablet. According to the method of applying the coloring substance - laser or inkjet. The question of which should be an engineering drawing, black and white or color, recently is definitely solved in favor of color. First, in view of significant progress in the field of color printing, which has become insignificantly more expensive in black and white. Secondly, the color carries additional information About the designed facility and helps increase the efficiency of the visual analysis of such drawings.

Shape \\ * mergeFormat

Fig. 2.2. a) rolled scanner; b) plotterlonal

The computer peripheral devices also include digital photo and video devices, which are currently widely used when collecting source data for road design.

For the organization of collective work on the project and operational exchange of information, computers are combined into local (intranet) and global (Internet) networks whose technical components are servers, network fees, modems, fiber optic networks, etc.

Software CAD is divided by system system and applied.

To system-wide software In the first place, operating systems (OS), which manage all the processes occurring in computers. The emergence and evolution of the OS occurred in parallel with the development of the computers themselves. If the creation of the first personal computer is associated with the company IBM.(www. iBM. com. ), then the first mass OS appeared for this computer from the company Microsoft.( www. Microsoft. Com.) and called MS.- DOS..

14-year-old way of evolution (from 1981 to 1995) MS.- DOS. Versions 1.0-7.0 contributed to the introduction of computers from solid engineering tasks to their widespread use in all spheres of life.

Since the beginning of the 90s for shift MS.- DOS. comes Windows (from the English - windows) also from the company Microsoft.that it allows you to simultaneously work with multiple programs (windows), easily switching between them without having to close and restart individual programs. At the initial stage of development Windows Served the role of the graphical interface for MS.- DOS..

With exit Windows 3.1 (1992) This operating system is associated as an independent, capable of working with the RAM of more than 640 KB, with scalable fonts TrueType..

Release in 1993 WindowsNt. (Reduction from New Technology - new technology) was well accepted by developers due to its heightened security, stability and developed API.-Interface WIN.32 Simplifying the preparation of powerful programs.

In 1995 it comes out Windows95 - the most friendly version version Windowsfor installing which is not required to pre-install DOS.; Her appearance makes a PC more accessible mass consumer. Windows 95 has a built-in protocol set. TCP./ IP. And it is allowed to use long file names.

Windows 98 (1998) - Last Version Windows On the basis of the old core operating on the foundation DOS.. System Windows 98 integrated with browser InternetExplorer 4 and compatible with numerous new hardware standards, including USB ports. Subsequent windows version Developed on the basis of nt kernel.

Currently (since 2001), most application programs, including CAD, operates running operating system MS.WindowsXp. (From English Experience - Experience).

New problem-oriented interface MS.WindowsXp. Allows you to master the principles of work in the shortest possible time operating system Even those users who have never come across the families of the family Windows. Used by WindowsXp. Extended Web Technologies open the possibility of sharing text and voice messages, creating Web projects of various levels of complexity and sharing applications not only on the local network, but also on the Internet.

The conditionally system-wide software can be attributed MS.Office., whose applications are ( text editor Word., spreadsheet Excel) Stated de facto standards in your class of programs. Almost all CAPRs forming text documents as output data, carry out this in the environment. MS.Word., but table forms - in the environment MS.Excel.

Applied programs, in addition to the CAD, can be attributed: vectorizers; geodesic data processing programs, remote sensing data; Database Control Systems (DBMS); Project Design Documentation Management Systems (SUPCD), etc.

The last of the listed (SUPCD) are extremely important in the work of project organizations, since largely ensure the functioning of quality control systems in the production of project products.

Of the many programs of this class, the most fully functional system is PartyPlus. (Developer - Loosen Soft, Moscow, www. lotsia. com. ).

PartyPlus. It is a professional system built in the client-server architecture based on Database Oracle, MS.SQL- Server, Sybase. and distinguished reliability, productivity, scalability and security.

Fig. 2.3. Party Plus Documentation Management System

The system contains a secure archive of documents, as well as built-in tools for free and predefined routing of documents, works and management of business processes. The system supports the mode of parallel collective work of various user groups and ensures the management of the entire project relating to the information, which allows the project organization to not only access the project description, but also to manage information about this project.

If there are several territorially distributed project departments in the enterprise, then with PartyPlus. You can organize the debt interaction of remote units when working on multiple projects.

PartyPlus. It has a function of keeping the history of all engineering changes in the project structure, the ability to compare the current state with a state to any date. There are means of supporting multivariate design with storage of options that have not included in the main project, tools to support work with version versions. There is an opportunity to set analogs or related elements for the project element, group items on various criteria.

System PartyPlus. Universal, maximum bending for solving problems in various industries, including the road industry, and is focused on equal work with various CAD.

2.2. Mathematical and methodical

Mathematical support - This is a combination of analytical and numerical methods, mathematical models of algorithms for the implementation of project procedures. The use of certain methods depends on the level of development of the CAD, the properties of the design objects and the nature of the tasks being solved.

At the initial stage of the development of CAD, algorithmization was carried out manual methods Design. This contributed to a reduction in design time, but the quality of design solutions was practically not improved.

The first work in the field of optimization of project decisions began in the 70s and were associated, first of all, with the design of the longitudinal profile. The works of E.L. Filstein and its method of "boundary iterations", V.I. Trechenkova and its method "Projection of the Gradient" established the position of the project line of the longitudinal profile, taking into account the minimization of the volume of earthworks. Already at this stage, it was necessary to abandon the presentation of the design line in the form of a sequence of direct and arc of circles, and Proine model of the design line in the form of a broken (linear splice). However, ethimetics did not affect the general (basic) principles of research and design of roads.

The transition in the 90s of the system automation of road design on the basis of digital location models led to a significant change in the entire technology of design and survey work.

During the "manual" road design, geodesic surveys were performed by a "pissing" method. The essence of this method is the following stages of work:

· Field tracing of the highway. At the same time, the tangential movement of the route is simultaneously the main move for all subsequent centering works, both at the stage of research and construction stage.

· Planned-high-altitude fixation of the track by truths and corner pillars.

· Picket breakdown on the highway. Not only the picket points, but also the positive (characteristic) points associated with the beliefs, the intersection of water flows, engineering communications and roads are broken down and secured.

· Double longitudinal geometric leveling of the track accepted by a par.

· Shooting disk. When breaking a picketing on the highway simultaneously carry out broken downs on all picket and positive points. In rectilinear sites, the trails are broken down perpendicular to the axis of the road, and in curvilinear sites - perpendicular to the tangent to the track. The length of the diameter takes such that the earthen canvas with all its structural elements are located.

Shots are carried out for the construction of longitudinal and transverse profiles according to the adopted track for the subsequent design of the earthlings, the organization of the surface drainage system, counting the volumes of earthworks and the preparation of project documentation.

As follows from the above, with a "pissing" method of researching a change in the position of the route and, therefore, all other projections at the project stage are not possible. Thus, the creative start of project activity is limited due to the predetermination of the route of the road, which significantly affects the quality of the final project decisions. Note also that in the field of tracing, in the absence of computer equipmentThe engineer, the sistering recorder was limited to the elementary scheme of rounding the "Clotoid-circular curve-clotoid" type track, whose breakdown was to produce according to the appropriate centering tables.

A completely different perspective opens the "undertaking" method of exquisition of roads, the priority use of which it became possible due to the achievements of electronic total equipment and computing technology.

Exquisitions on this method are as follows:

· In the strip of possible design solutions defined on the pre-project stage, the main stroke (network of moves) is laid and fixed.

· Total historic shooting band varying. At the same time, high performance of the work is ensured, since the measurements necessary to determine the spatial coordinates of the sealing points of the terrain are carried out comprehensively using a single geodesic instrument - a tacheometer.

· A digital location model is read from the electronic tacheometer to the computer, which is the basis for all subsequent project procedures.

Note that with the "undertaking" method of research, the location of the track is determined at either the stage of research, and at the design stage (in cameral conditions). This makes it possible to vary the location of the track by almost any stage of the design, to be used to establish the location of the route and its descriptions with modern mathematical methods, including optimization.

Considering the three-dimensional nature of the TSMM and the surfaces generated by it, the unique possibility of spatial tracing of roads appears. Currently, the methodology and algorithms of spatial tracing are successfully developed within the framework of the CAD and the arsenal of advanced technologies should be replenished soon for road project practices.

Of the many methods of computational mathematics that have become available in the system of system automation of design work, we will stop on splines and beam curves used in terms of automated tracing roads in terms of and longitudinal profile.

Interpolation splines.As is known, the term "spline" comes from the name of the drawing tool - a thin metal or wooden line, which bends so to pass through the specified points ( x I., y I.= f.(x I.)).

Then the spline in the equilibrium position takes a form that minimizes its potential energy. And in the theory of beams it is established that this energy is proportional to the integral of the arc length from the spline curvature square:

under conditions S.(x I.) = y I..

Fig. 2.4. The outlines of the spline as a mathematical analog of the line

Spline can be determined by 2 ways: based on the mutual reconciliation of simple functions and from solving the minimization problem.

The globes determined by the first method can be attributed to the interpolation splines that are necessary for the analytical presentation of discretely specified information.

Smoothing splines determine most often based on the 2nd method. It is smoothing splines who must find the wider application to optimize those design solutions that are approximate in the initial stage of consideration, as a rule.

In project practices, they usually apply, as a rule, the range of the 1st and 3rd degree. The range of 1st degree (linear) serve, firstly, good and accessible illustrations to understanding the processes of constructing spline algorithms, secondly, sufficient to describe the geometric elements of the roads represented in the form of broken lines (trunk and tangential moves, longitudinal and transverse Earth profiles, etc.).

1st degree spline. The range of 1st degree (broken) is quite simple for understanding and, at the same time, the time reflects the basic properties of spline functions. From a mathematical point of view, the spline of the 1st degree is a piecewise continuous function, on each segment described by the equation of the form:

y.= a I.+ b i X., (2.2)

where i. - number of the interval under consideration between interpolation nodesx I. and x I. + 1 .

As can be seen from formula (2.2), on the element interval, the view of the equation does not differ from the generally accepted expression direct. In general, the loloral equation (1st degree splice) in the matrix form can be written as:

(2.3)

This system of linear equations does not require a joint solution and decays to solve each equation separately. Spline, the solution of which is associated with the calculation of the subsystems of a small dimension, in this case - the equations of the first order, will be called local.

Interpolation spline 1st degree - this is a broken passing through points (x i, y i). For aggregate x I.(i \u003d.0, 1,… , N.) in the interval [ a, B.] The condition should be performed. x i 1.

Using the Lagrange polynomial, you can build a spline for interval i -(i +.1):

(2.4)

Designation S. 1 (x) We will understand as a spline function of the first degree. Otherwise, equation (2.4) can be written:

(2.5)

If you take on the form of equations (2.2) and (2.5) coincides. To build an algorithm and compiling the procedure for building and calculating splines, it is necessary to remember only 2 n.+2 numbers.

Spline 3rd degree.The range of the 3rd degree (cubic) is a piecewise continuous (continuity of the 1st and 2nd derivatives) a function consisting of segments of cubic parabola.

Currently, there are many algorithms for constructing and calculating Cubic splines, which is due to their wide use in solving technical problems associated with sythlepolation of curves and surfaces.

When solving the task between N nodes are located n.-1 fragments of cubic curves, and the cubic curve, in turn, is determined by 4 parameters. Since the value of the function and 1st, 2nd derivatives ( X S., X.¢ S., X.² S.) continuous in all ( n.-2) - internal nodes, we have 3 ( n.-2) Conditions. In nodes X si.= X I. Another n conditions are superimposed on X S.. From here we get 4. n.-6 Conditions. For the unambiguous definition of the spline, two more conditions are necessary, which are usually associated with the so-called edge (boundary) conditions. For example, it is often accepted simply. In this case, we obtain the required number of conditions for determining the natural splines in the form:

The disadvantage of this spline is that it does not have a change in the form on the site between two rigidly fixed interpolation points. Only the movement of one of the interpolation points can be achieved some change in the form of a spline curve. At the same time, due to the fact that the cubic interpolation spline refers to nonlocal methods of approximation, its values \u200b\u200bat points that do not coincide with the mesh nodes δ: a.= x. 0 x n \u003d b.depends on the entire totality of values f I. = f.(x I.), i.= 0, 1 ,…, N., and from the values \u200b\u200bof the edge conditions at points a., b.; Therefore, the desired effect of changing the shape of a spline curve in one place interval interval may be overlapped with undesirable changes for the rest of the rest.

However, methods of combating this unpleasant phenomenon are known. This, firstly, the use of local interpolations of the Hermite type, for which the spline value between the grid nodes depends on the values \u200b\u200bof the function and its derivatives only from some neighborhood of this gap.

Secondly, interpolation based on rational splines. Keeping one of the most important properties of cubic spline interpolation - the simplicity and effectiveness of implementation on the computer - rational splines have the possibility of approaching functions with large gradients or break points, while eliminating oscillations inherent in the usual cubic spline.

Rational spline function call function S.(x.), which is at each interpolation interval [ x I., x I. +1] written in the form

(2.7)

where t \u003d.(x - X I)/ h i, h i \u003d x I +. 1 - x I,p I,q I. - set numbers, -1 p I,q i and at the same time continuous with its first and second derivatives.

From the expression (2.7) it can be seen that when p i \u003d Q i \u003d0, i \u003d.0, 1,…, N.-1, rational spline turns into a regular cubic spline. In addition, we can assume that the first degree spline is also a special case of a cubic spline, since at all p i, q i -\u003e ∞i \u003d.0, 1,…, N.–1, Fair S.(x.)–> f I.(1– t.)+ f I. +1 t,x.Î [x I,x I. +1 ].

Thus, it can be expected that when using rational splines by proper selection of free parameters. p I, Q i A high accuracy of the approximation on the plots of sufficient smoothness of the interpolated function is achieved, and the requirements of a qualitative character - bulge and monotony are satisfied in areas with large gradients.

The use of a rational spline function allows you to describe the uniform dependence of the track with a maximum approximation to the track specified by traditional elements. Variating the values \u200b\u200bof the coefficients p I. and q i, It is possible to fully imitate the spline function of the traditional elements of the track plan (direct, circular curve, clotoid).

The "weak" place in justifying the interpolation splines as a universal mathematical apparatus when tracing roads is assumption (condition) that the interpolation nodes are assigned to the designer correctly and when calculating the values \u200b\u200bof the spire itself, the adjustment is not subject to.

Let's analyze how in practice nodes are prescribed?

If tracing is performed on the basis of a card or topographic plan, then a sketching line of the road is carried out, which, according to the designer, is the most appropriate under specified conditions, "by hand" or using mechanical devices. Next, interpolation nodes are recorded on the sketching line and their coordinates are measured. At the same time, there are no strictly formalized algorithms for the purpose of the location of the nodes, there are only a number of practical advice. In particular: the frequent arrangement of nodes leads to the oscillation of the curvature of such a spline due to the inevitable error of the shooting of the coordinates of the interpolation nodes; Their rare location causes substantial deviations of the spline-highway from the sketch-line generating line.

If tracing is performed on the field of field surveys, the nodes of the spline interpolation, in this case, are the shooting points of the digital model of the terrain error in establishing their coordinates even more obvious due to the presence of random and systematic errors.

A good approximation of the spline-highway to the sketching option and, at the same time, its sufficient smoothness (smoothness) can be achieved, as a rule, only with multiple intuitive adjustment of the interpolation node designer.

It follows that the interpolation splines are not a mathematical apparatus of optimal tracing, but only convenient and in many tasks extremely effective tools for computer processing sketch-appointed design solutions. The quality of such solutions is essentially depends on the qualification of the designer.

From the above reasoning, it follows that the setting of the task of tracing on the basis of splines should assume the following: interpolation nodes of the sketching route, and in the case of reconstruction - the source track, are assigned approximately (with admission) and their exact location is calculated according to certain patterns that take into account a number of fundamental target settings Trace process. In mathematical terminology, this problem can be attributed to the tasks of generating geometric forms according to their gross (approximate) descriptions or smoothing tasks.

Smoothing splines. As a mathematical apparatus, smoothing splines are used as a mathematical apparatus, which minimize the functionality of the form:

with restrictions, for example,

In the entry of the functional q \u003d1, 2; S.(x I.) - spline; r. I. - VE coefficient of interpolation assembly; f. 0 (x I.) - The function of the initial approximation.

Restrictions can be the most different and in the case of road tracing it is: restrictions on the permissible radius, the direction of the tracing plan of the oclon in the longitudinal profile, etc. At the same time, the so-called "boundary conditions" should be added for the splines of the third degree x. 0 = ax n \u003db.ensuring the uniqueness of building a spline. For example, it may be the conditions of the specified initial and final direction of the designed section of the track S.¢ (x A.), S.¢ (x B.).

From the form of recording joint conditions (2.8) - (2.10) it follows that this is the problem of conditional optimization.

Condition (2.9) allows the interpolation nodes in the established variation corridor according to a given algorithm. The configuration of the completion of the iterative optimization process is the following condition (2.10) and means that at each further iteration step, the shift of any of the nodes will not exceed the magnitude d..

If in the condition (2.9) e. I. \u003d 0, then we again come to the concept of interpolation splines. Hence it becomes obvious that interpolation splines are just a special case of smoothing splines.

The choice of smoothing splines for further detailed consideration only in the form of algebraic polynomials and only the 1st and 3rd degree from the variety is due to the fact that it is the most simple in computer implementation of the spline and, at the same time, have sufficient approximative properties for the descriptions of the outlines. Trails and its differential analysis. In the case of 1st degree splines, this analysis (1-EI 2-E derivatives) can be performed as separated differences, and for the 3rd degree spline - direct differentiation of the function.

Functional (2.8) Well models the task of tracing roads during their reconstruction, which is to achieve the minimum deviation of the designed route from the existing, while simultaneously under the slope and curvature in the longitudinal profile, and on curvature and the rapid growth rate of curvature in terms of claims For this category of road. The minimum deviation is achieved at the expense of the second term, and the conditions for curvature and the slope - the first terms of the functional (2.8).

With the co-minimization of the two terms, the ratio between them is regulated by weight coefficients r. i, which must be defined normally.

Consider the optimization capabilities of the functional (2.8) in ascending order of its complexity.

Second term functional

it is known as the method of least squares, and it is a function n.+ 1st variable S.(x I.), i \u003d.0, 1,…, n.. Minimizing the latter disintegrates in this case to minimize individual terms independently for each variable.

In the case of the application of the 1st degree splines, the first components (2.8) will be recorded as

.(2.12)

Consider the linear approximation of the functional of the length of the arc curve

(It is assumed here that | S.`(x.) | few). Obviously, the solution of the problem of minimizing the functional (2.13) coincides with the solution of a linearized problem of finding an element of minimum length. The solution obtained is often referred to as a splined in a convex set.

After the substitution of the first derivative of the spline, which coincides in this case, with a separated difference, takes the form

(2.14)

where h I.= x I. +1 –x I..

Differentiate by variable S.(x I.) and fold two consecutive terms of equations containing this unknown:

Equating the resulting amount zero and expressing unknown S.(x I.), we get

Here the sign "\u003d" is an assignment operator. If you take the interpolation step uniform, that is h i \u003d.const.The optimization process (step-by-step iterations) in the graphical interpretation will be completely understood (Fig. 3. 10).

The rapid convergence of the iterative process allows you to recommend this method to pre-develop design solutions on the project line of the longitudinal profile. In this case, the radius of curvature and the bias of the project line can be monitored by building the first and second separated differences.

Fig. 2.5. Graphic Interpretation of Linear Spline Smoothing

Joint consideration of the amount of functionals (2.12) and (2.14) gives us a recurrent formula for optimization:

The convergence of the iterative process here, compared with formula (2.17), is lower and significantly depends on the value r. I.. Weight coefficient r. I. Allows you to slow down or accelerate the iterative process at individual points (nodes) and may, for example, for the design line, to serve as a means of accounting for the volume or value of the construction of an earth canvase (road works) on a portion of a single length.

Consider the first characteristic functional (2.8) in relation to cubic splines:

Similarly, the solution of the problem of splines in the convex set describes (in a linearized formulation) the provision occupied by an elastic slat in the corridor of restrictions. When replacing the second derivative of the second separated difference, this functionality will take the form:

where S.¢ (x A.), S.¢ (x B.) - Some of the possible edge conditions of the cubic splice. With regard to the design line is a bias in the initial ( x A.) and the ultimate ( x B.) Points of the designed section of the road.

Differentiation and summation of the equations will give us the corresponding recurrent formulas, which are detailed in the special literature.

The design of the road roundings in terms of the classic scheme "Clotoid - Circular Curve - Clotoid" is sufficiently reasonable from theoretical positions, but in practice such a scheme has many flaws and inconvenience. Without going into their essence, we note that if you use any function that could in some extent to model the classic scheme (composite curve), then from the standpoint of the convenience of algorithm and the organization of the "Engineer-Computer" dialogue Effectively.

Bezier curves. In 1970 Pierre Bezier (French mathematician) picked up the components of a parametric cubic polynomial in such a way that their physical meaning became very visual and very suitable for solving many applied tasks, including for the purpose of designing roads on the principle of "tangential tracing".

Formula Bezier for cubic polynomial ( n.\u003d 3) has the following form.

Let be r I. = , i.= 0, 1, 2, 3, then for 0 ≤ t ≤1:

or in matrix form:

The matrix M. It is called the base matrix of the Bezier cubic curve.

The curve presented in the form of Beziers passes through points r. 0 I. r. 3, has a tangent at point r. 0 directed from r. 0 K. r. 1, and tangent at point r. 3 directed from r. 2 K. r. 3 .

Straight R 0 R 1 , R 1 R 2 I. R 2 R 3 form a figure, called the characteristic (decisive) broken, which predetermines the outlines of the Bezier curve (Fig. 2.6).

To build a curve, set dots R 0 I. R 3, through which the curve should pass, then on the desired tangents to this curve at the points R 0 I. R 3 set dots R 1 I. R 2. Changing lengths of segments R 0 R 1 I. R 2 R 3 Various an outline curve, giving it the desired shape.

Fig. 2.6. Segment Cubic Bezier Curve

The main controlled value in the design of curves in the plan is the radius of curvature. In order to calculate the radius of curvature at every point of the curve, it is necessary to know the values \u200b\u200bof the first and second derivatives of the radius-vector point. For a cubic Bezier curve, the first and second derivatives are calculated by the formulas below:

Then the curvature (the reverse radius of curvature) is calculated by the formula:

In addition to the curve of the Bears of the 3rd Order (cubic) for the purpose of tracing roads, it is also possible to use the curves of Beziers of the 2nd, 4th and 5th orders. The corresponding formulas for calculating the radius vectors (and their derivatives) for these curves are shown below.

Curve Bezier 2nd order:

Flashing curve of the 4th order:

Flashing curve of the 5th order:

Union of elementary curves Bezier Γ (1), γ (2), ..., γ ( L.), in which the terminal point of the curve γ ( I.) , i.= 1, 2,…, l -1 coincides with the initial point of the curve γ ( I. +1), it turns out a composite curve of the Bezier. If each curve Γ ( I.) is given by the parametric equation of type

r. = r. ( I.) (t.), 0 ≤ t.≤ 1,

this condition is written as follows:

r. ( I.) (1) = r. ( I. +1) (0), i.= 1, 2,…, l.–1.

In particular, in order for the tangent of the composite curve Bezier, determined by the set of points P. 0 , P. 1 , …, P. m. , changed continuously along this curve, it is necessary that the top three P. 3 I. -1 , P. 3 I., P. 3 I. +1 (i. ≥ 1) were collinear, that is, they lay on one straight line (see Fig. 2.7).

Fig. 2.7. Composite Cubic Bezier Curve

Spatial curves Beziers. Above, in reasoning about Bezier-curves, the flat layout of the support points of the track was understood and, accordingly, the representation of only flat curves was considered. In general, the appearance of the characteristic broken beams are set by the points of three-dimensional space. P I.(x I., y I., z I.), i.= 0, 1 ,…, m..

Then the spatial curve of the radiance m. Determined by the equation having the following form:

where are the polynomials of Bernstein.

The matrix record of parametric equations describing the spatial curve of Beziers has the form:

0≤ t. ≤ 1,

A more detailed presentation of the spatial tracing of roads is given in ch. five.

Methodical support - A combination of methodological materials that contribute to the functioning of CAD.

Professional CAPRs are usually a methodological support in the form " Reference guides"In paper. The main menu of such systems also contains a certificate (assistance) section, which presents a description of the main project procedures.

During the operation of the CAD, the experience of rational development of design solutions is accumulated based on the entire totality of the system tool. This experience is usually set out in the form of "practical guidelines (benefits)" and contributes to improving the efficiency and quality of engineering labor.

2.3. Information and Organizational Provision

Information Support - This is a combination of funds and methods for building an information base for design purposes.

Part information support Include: state standards (GOST), building standards (CH), construction standards and rules (SNiP), departmental construction norms (VNS), typical design solutions for structures and elements of roads. All of the above regulatory information materials exist in paper or in the form of electronic analogs.

Another part of the information support exists only in electronic form and is an integral part of the CAD. These are symbol libraries (see Fig.2.8), classifiers and codes, patterns of typical elements in graphic algorithms.

Fig. 2.8. Library Conditional Sign for Topographic Plan

In the process, the design is also used regional information. It includes information and environmental and environmental information, data on the relief and geological structure of the locality, information about the location of the quarries of soils and stone materials, etc.

On another classification, information can be divided into input, intermediate and output. Entrance - a set of source data required for the adoption of a design solution. Intermediate - previously obtained as a result of solving one tasks and used to solve others, but not the final results of solving problems. Output - obtained as a result of solving tasks and intended for direct use in design.

Organizational support Represents a combination of organizational and technical measures aimed at improving the efficiency of the functioning of the CAD. These include: change the organizational structure of the project organization, its departments and divisions; Redistribution of functions between departments; Changes in the technology of design and survey work and staff staff, improving the design of the designer of the SAD system, the organization and functioning of project management quality management systems based on international standards ISO 9001: 2000.

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project proceduresfor which there is an appropriate software;

interaction between designers and computers, support for the interactive mode of operation;

interaction between members of a team working on a common project.

The first of these requirements is performed if there are computing machines and systems with sufficient productivity and memory capacity in CAPR.

The second requirement belongs to the user interface and is performed by including convenient data input / output tools in the CAPR and, above all, graphical information sharing devices.

The third requirement determines the association of CAD hardware to the computing network.

As a result, the general structure that CAD is a network of nodes related to each other. data transfer medium (Fig. 5.1). Nodes (data stations) are designer workplaces, often referred automated jobs (AWP), or workstations (WS - Workstation) ; They may also be large computer (mainframes), individual peripheral and measuring devices.

It is in AWPs should exist funds for the design interface with a computer. As for computing power, it can be distributed between different computing nodes.

Data transfer medium Presented by data transmission channels consisting of communication lines and switching equipment.

In each node you can allocate term Data Equipment (ODO)performing a certain design work and data channel termination equipment (ACD)designed to communicate the ODO with data transfer medium. For example, as an ODA can be considered personal ComputerAnd as an ACD - inserted into the computer network fee.

Data transfer channel - A tool of bilateral data exchange, including ACD and communication line. Line Communication referred to as part of the physical environment used to distribute signals in a specific direction; Examples of communication lines can serve as a coaxial cable, twisted pair of wires, fiber optic communication line (Vols).

Close to the concept of the channel ( Communication channel), under which the means of one-sided data transfer is understood. An example of a communication channel may be a frequency band allocated to one transmitter during radio communications.

Fig. 5.1.

In some line, you can form multiple communication channels, each of which is transmitted to your information. At the same time they say that the line is divided between several channels.

5.2. Types of networks

There are two methods for separating the data line: temporary multiplexing (otherwise - separation in time, or TDM - Time Division Method), in which each channel is allocated some time quantum, and frequency separation (FDM - Frequency Division Method)In which the channel is allocated some frequency band.

In Sappa small design organizationsNo more than one-time computers, which are placed at low distances from each other (for example, in one or several adjacent rooms), combining computers network is local. Local computing network (LAN), or LAN (Local Area Network)It has a communication line to which all network nodes are connected. At the same time, the topology of connections of nodes (Fig. 5.2) can be tire (BUS), ring (Ring), Star (STAR). The length of the line and the number of connected nodes in the LAN are limited.

Fig. 5.2.

In larger on the scale of design organizations, tens of hundreds and more computers relating to different design and managerial units and placed in the premises of one or more buildings are included. Such a network is called corporate. In its structure you can highlight a number of LANs, called substints, and the LAN communications tools. These tools include switching servers (subnet interaction blocks). If the switching servers are combined by the Data Transmission Data Division separated by the LAN, then they form a new subnet called reference (or transport), and the entire network turns out to be part of the hierarchical structure.

If the buildings of the project organization are removed from each other for considerable distances (up to their location in different cities), corporate network on its scale becomes territorial Network (WAN - Wide Area Network). IN territorial network distinguish mains Data channels (main network) having a significant extent and data transmission channelsbinding a LAN (or a set of LANs of a separate building or campus) with a backbone network and called subscriber line or compound "Last Mile".

Usually, the creation of a highlighted backbone network, i.e., the network serving the only organization is too expensive for this organization. Therefore, more often resort to services provider, i.e., firms providing telecommunication services to many users. In this case, within the corporate network, communication at considerable distances is carried out through main Network of General. As such a network, you can use, for example, a city or long-distance telephone network or territorial data network data networks. The most common form of access to these networks is currently accessing the global Internet computing network.

The structure of the CAD for a large organization is presented in Fig. 5.3. Here is a typical structure of large corporate CAD networks, called architecture client-server.. In networks " client server. "One or more nodes are distinguished. serversThat runs on the network managers or common project functions for many users, and the rest of the nodes (jobs) are terminal - they are called customers, users work in them. In general the server call a set of software tools focused on performing certain functions. But if these tools are focused on a specific node of the computing network, then the concept of "server" refers to the network node.

Network "client peer-to-peer networks Found a predominant distribution in small-scale CAD.

In accordance with the switting methods, there are networks with switching channels and switching packages. In the first case, when exchanging data between nodes A and the network, a physical connection is created between A and B, which, during a communication session, is used only by these subscribers. An example of a network switched network can serve telephone network . Here the transmission of information occurs quickly, but the communication channels are used inefficient, as long-term pauses and the "idle" canal are possible. When switching packets of a physical connection, which would connect subscribers at each time BUT and IN, not created. Messages are divided into portions, called packageswhich are transmitted in a branched network from and to in or back through intermediate nodes with possible buffering (temporary memorization) in them. Thus, any line can be divided by many messages, alternately skipping the packages of different messages with the maximum filling of these pauses.

Requirements for CAD technical means. SAD technical support structure

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