An eccentric orifice plate is analogous to a concentric orifice plate with a circular orifice located eccentrically with respect to the axis of the pipeline. When orienting the flow section in the lower part of the round pipe, it is possible for the contamination contained in the measured liquid to flow through the diaphragm without the formation of clogging and deposits in front of the diaphragm plate. Most often, the diaphragm is installed in the pipeline in a flange connection. In addition to ČSN / ČSN / standards, sealing surfaces on diaphragms can also be manufactured in accordance with EN, DIN, GOST, American ASME and ANSI standards, or at the request and requirements of the customer.
The ideal solution is to place the differential pressure tap vertically at the top of the diaphragm; point pressure selection. The differential pressure outputs are always adapted to the customer's agreement with the customer. different options connecting the primary element to the measuring circuit.
The ISO / TR 15377 standard, in conjunction with the provisions of the ISO 5167-1 standard, sounded the possibility of using eccentric diaphragms for pipes with a diameter of 100–1000 mm. The eccentric orifice plate is available as a point tapped orifice plate, a disc mounted between flanges with a point tapping, a disc mounted directly between the flanges or as a measuring line.
The main parts of the eccentric point orifice include a two-piece differential pressure point tapping lip and a diaphragm disc. The diaphragm disc is sandwiched between two lip pieces and secured with a gasket. Pressure tapping is removed from the edge. The diaphragm disc is removable and replaceable. Typical construction widths for spot sampling diaphragms are 40–60 mm.
The most common steel grades for the production of the bezel edge are carbon steel or stainless steel. The material design of the eccentric diaphragm disc, taking into account the application in the petrochemical, chemical and nuclear industries - stainless steel and steel with a high nickel content (Inconel, Hastelloy).
The eccentric diaphragm is available as working tool measurements.
The eccentric orifice plate is used in cases where the formation of deposits, tarry sediment layers or condensates is expected - that is, when measuring the flow rate of heterogeneous mixtures (liquids with mechanical impurities and gases containing solid or liquid components) in pipelines. The production of an eccentric orifice plate can be coordinated in a different range of nominal diameters of pipes than indicated above. An eccentric orifice plate can be installed in horizontal or inclined pipelines.
Physical structure FDD Sector 512 bytes 79 lane 0 lane Sides - 2 lanes on one side - 80 (0-79) Sectors on one lane - 18 Sector capacity bytes
1 sector Boot sector... It is used if the disk is a system disk 2 sector File name Address of the first sector File size, Kbytes Creation date Creation time ………………… File sector File sector D D D D D D2 E 69 D D1 E 71 ……………… ... 2662 sector Data of the first file Number of the next sector End of file
Clusters When writing files, an integer number of clusters will always be used, so the minimum file size equal to size one cluster. The file is written to random free clusters. For example, File_1 can occupy clusters 34, 35, 47, 48, and File_2 occupies clusters 36 and 49.
Information capacity FDD Number of sectors: 2 * 80 * 18 = 2880 Total information capacity: = 2880 * 512 = = bytes = = 1440 KB = 1.40625 MB Information capacity: = () * 512 = = 1.39 MB
NTFS FILES PLACEMENT TABLE. File system for Windows. Allows you to set different cluster sizes (from 512 bytes to 64 KB, 4 KB by default). Uses a logging system to improve reliability file system... A journaled file system maintains a list of the changes it will make to the file system before actually writing the changes. NTFS over FAT32 increases reliability and efficiency disk space... ext3 and ReiserFS. Journaled file systems for the Unix OS. An ext3 block (cluster) can be 1 to 8 KB in size. In ReiserFS, data from multiple files can be stored in one block. The maximum size of a ReiserFS file system is 16 TB.
HFS FILES PLACEMENT TABLE. Hierarchical Journaled File System for Mac OS. CDFS. File system for working with optical CD and DVDs, based on the ISO 9660 standard, according to which the file name can not exceed 32 characters and the depth of nesting of folders - no more than 8 levels. UDF. Multi-system file system for working with optical CD-RW and DVD ± RW discs.
FORMATTING INFORMATION MEDIA Formatting the physical structure of a disk consists in creating concentric tracks on the disk, which, in turn, are divided into sectors. In the process of formatting, the magnetic head of the drive places marks of tracks and sectors in certain places on the disk. Formatting the logical structure of a disk creates a root directory and a file allocation table. Large in volume hard drives it is recommended to split into sections, i.e. independent areas on the disk. Partitions can be formatted in various file systems, and thus logical drives are created.
Formats full quick After full formatting all information stored on the disk will be destroyed. After a quick formatting, the information, that is, the files themselves, will be saved, and, in principle, it is possible to restore the file system. Quick format cleans up the root directory and file allocation tables. Full formatting involves creating the physical and logical structure of the disk
C: \ Windows> format A: / T: 79 / N: 19 format A: / T: 79 / N: 19 "> format A: / T: 79 / N: 19"> format A: / T: 79 / N: 19 "title =" (! LANG: C: \ Windows> format A: / T: 79 / N: 19"> title="C: \ Windows> format A: / T: 79 / N: 19"> !}
2. A single-sided diskette has a capacity of 360 KB. How many tracks will there be on the disk if each of them contains 9 sectors, and each sector contains 1,024 characters of the 32-character alphabet? Solution: 1) N = 2 i; 32 = 2 i i = 5 bits - information weight one character 2) = bit =: 8 = 5760 bytes - the size of one track 3): 5760 = 64 tracks
Problem 1. How large is a double-sided floppy disk if each side is split into 80 tracks with 15 sectors per track? The size of each sector is 4096 bits. Problem 2. Text written using a 32-character alphabet occupies 10 full sectors on a 300KB single-sided floppy disk. The diskette is divided into 40 tracks with 15 sectors. How many characters does this text contain? Problem 3. As a result of damage to a double-sided floppy disk, 20% of the sectors were defective, which amounted to a byte. How large is the diskette? Task 4. How many floppy disks with a capacity of 1440 KB can accommodate content hard disk volume of 0.5 GB?
Homework pp questions
Concentric
CONCENTRIC oh, oh. concentrique adj. Wed-lat. concentricus. 1 ... M at. Having a common one. Sl. 18. Concentric, refers to two or more compasses, which are made from one center. ЛВ-1 1 502. On the circles of concentric circles. Cat. Geodet 306. // Sl. 18 10 155. These lines should be concentric (converging) when it comes to preparing a decisive blow, and then, after victory, - eccentric (diverging). Jomini Essays on the military. claim. 1 160. Between these circles there are naturally parallel, concentric and eccentric circles. N. Khmelnitsky Ball. // Nev. 1846 166. Five batteries, which somewhat diverted the concentric fire of the French. Moltke 1937 51.
2. Based on concentrism... Concentric teaching. BAS-1. Concentrically , adv. The circles are concentric. BAS-1. - Lex... Jan. 1804: concentric; SAN 1847: concentrate and/ Česky; SAN 1912: concentrate and/ rationally; Sl. 18: concentric 1766, concentric 1755.
Historical Dictionary of Russian Gallicisms. - M .: ETS Dictionary Publishing House http://www.ets.ru/pg/r/dict/gall_dict.htm. Nikolay Ivanovich Epishkin [email protected] . 2010 .
Synonyms:See what "concentric" is in other dictionaries:
CONCENTRIC- having a common center with another, but unequal dimensions, for example, concentric circles, have common center but different radii so that one lies inside the other. Control. also in figurative. meaning, e.g. the th system of public education, when different ... ... Dictionary of foreign words of the Russian language
CONCENTRIC- having a common center with something; concentric circles of a circle of different radius with a common center ... Big Encyclopedic Dictionary
CONCENTRIC- CONCENTRIC, concentric, concentric (book). 1. Having a common center. Concentric circles (mat.). 2.add. to concentr in 2 values. (ped.). Concentric teaching system. Ushakov's explanatory dictionary. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary
CONCENTRIC- CONCENTRIC, oh, oh (special). Having a common center; against. eccentric 1. Concentric circles. Ozhegov's Explanatory Dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Ozhegov's Explanatory Dictionary
concentric- adj., number of synonyms: 2 homocentric (1) concentric (4) ASIS synonym dictionary. V.N. Trishin. 2013 ... Synonym dictionary
concentric- - [A.S. Goldberg. The English Russian Energy Dictionary. 2006] Topics energy in general EN concentricc / c ... Technical translator's guide
concentric- oh, oh. Having a common center (opposites: eccentric). Round circles. To the circle. ◁ Concentric, adverb The circles are located to. Concentric, th, th; chen, chna, chno. = Concentric. Concentricity, and; f. * * * concentric having with ... ... encyclopedic Dictionary
Concentric- having a common center; concentric circles of a circle of different radius with a common center ... Great Soviet Encyclopedia
Concentric
Concentric- I adj. 1.rel. with noun concentrates I associated with it; concentric I 1 .. 2. Peculiar to concentrates [concentric I], characteristic of them; having a common center; concentric I 2 .. II adj. 1.rel. with noun concentrates II, concentrism associated with ... ... Modern explanatory dictionary Russian language Efremova
Books
- Biology. Grade 8: a work program based on the textbook by N.I.Sonin, M.R.Sapina. UMK "Sphere of life". Concentric course. FSES, Konstantinova I.V .. The manual presents working programm in biology for grade 8 (concentric course), developed in accordance with the Federal State Educational Standard, the planned results of the main general education by… Buy for 148 rubles
- Biology. Grade 9: a work program based on the textbook of S. G. Mamontov, V. B. Zakharov, I. B. Agafonova, N. I. Sonin. UMK "Sphere of life". Concentric course, Konstantinova I.V .. The manual presents a work program in biology for grade 9 (concentric course), developed in accordance with the FSES LLC, the planned results of basic general education in ...
Logical disk structure
Formatting disks. In order to store information on a disk, the disk must be formatted, that is, the physical and logical structure of the disk must be created.
Forming the physical structure of a disc consists in creating concentric tracks on the disc, which, in turn, are divided into sectors. To do this, during the formatting process, the magnetic head of the drive places track and sector marks in certain places on the disk.
After formatting a 3.5 "floppy disk, its parameters will be as follows (Fig. 4.24):
- sector information capacity - 512 bytes;
- the number of sectors per track - 18;
- tracks on one side - 80;
- sides - 2.
 |
| Figure 4.24. Physical structure of a floppy disk |
The logical structure of floppy disks. Logical structure magnetic disk is a collection of sectors (512 bytes in size), each of which has its own serial number(for example, 100). The sectors are numbered in a linear sequence from the first sector of the lead-in to the last sector of the last track.
On a floppy disk, the minimum addressable element is sector.
When writing a file to the disk, an integer number of sectors will always be occupied, so the minimum file size is the size of one sector, and the maximum corresponds to the total number of sectors on the disk.
The file is written to arbitrary free sectors, which can be located on different tracks. For example, File_1 with a volume of 2 KB can occupy sectors 34, 35 and 47, 48, and File_2 with a volume of 1 KB can occupy sectors 36 and 49.
In order to be able to find a file by its name, there is a directory on the disk that is database.
The file record contains the file name, the address of the first sector from which the file begins, the file size, as well as the date and time of its creation (Table 4.5).
Full information about the sectors that the files occupy is contained in the File Allocation Table (FAT). The number of FAT cells corresponds to the number of sectors on the disk, and the cell values are the file allocation chains, that is, the sequence of addresses of the sectors in which the files are stored.
For example, for the two files considered above, the FAT table from 1 to 54 sectors takes the form presented in table. 4.6.
The allocation chain for the file File_1 looks like this: the initial 34th sector stores the address 35, the 35th sector stores the address 47, the 47th - 48, and the 48th - the end-of-file character (K).
Sectors from 2 to 33 are allocated on the floppy disk to accommodate the directory - database and FAT tables. The first sector is allocated for placement boot record operating system. The files themselves can be written starting from sector 34.
Types of formatting. There are two different kinds formatting disks: full and quick format... Full formatting includes both physical formatting (checking the quality of the magnetic cover of the floppy disk and its layout into tracks and sectors), and logical formatting(creating a directory and file allocation table). After full formatting, all information stored on the disk will be destroyed.
Quick format only cleans up the root directory and file allocation table. The information, that is, the files themselves, are saved and, in principle, it is possible to restore the file system.
Standard floppy formatting
1.In context menu select item Format... A dialog box will open Formatting... By switch Formatting method select item Complete.
In field Label you can enter a disc title. To get information about the formatting results, select the checkbox Display a report on the results. Click the button Begin.
In order to protect information from unauthorized copying, you can set non-standard disk formatting parameters (number of tracks, number of sectors, etc.). This formatting is possible in MS-DOS mode.
Non-standard floppy disk formatting
1. Enter the command [Programs-MS-DOS Session]. The MS-DOS Session application window appears.
2. Enter the command for non-standard formatting of the floppy disk A :, which will have 79 tracks and 19 sectors on each track:
Informational capacity of floppy disks. Consider the difference between the capacity of an unformatted floppy disk, its information capacity after formatting, and the information capacity available for writing data.
The 3.5 "floppy disk has a declared capacity of 1.44 MB.
Let's calculate the total information capacity of the formatted floppy disk:
Number of sectors: N = 18 x 80 x 2 = 2880.
Information capacity:
512 bytes x N = 1,474,560 bytes = 1,440 KB = 1,40625 MB.
However, only 2847 sectors are available for recording data, that is, the information capacity available for recording data is:
512 bytes x 2847 = 1,457,664 bytes = 1,423.5 KB "1.39 MB.
Logical structure hard drives. The logical structure of hard disks is slightly different from the logical structure of floppy disks. The smallest addressable element of a hard disk is cluster, which can include several sectors. The cluster size depends on the type of FAT used and the capacity of the hard disk.
On a hard disk, the smallest addressable element is cluster which contains several sectors.
The FAT16 table can address 2 16 = 65 536 clusters. For discs large capacity the cluster size turns out to be too large, since the information capacity of hard disks can reach 150 GB.
For example, for a 40 GB disk, the cluster size will be:
40 GB / 65536 = 655 360 bytes = 640 KB.
An integer number of clusters is always allocated to a file. For example, text file containing the word "informatics" is only 11 bytes, but on disk this file will occupy the entire cluster, that is, 640 KB of disk space for a disk with a capacity of 150 GB. When placed on a hard disk a large number small files, they will occupy clusters only partially, which will lead to large losses of free disk space.
This problem is partially solved by using the FAT32 table, in which the cluster size is assumed to be 8 sectors or 4 kilobytes for a disk of any size.
In order to more reliably save information about the location of files on the disk, two identical copies of the FAT are stored.
Converting FAT16 to FAT32 can be done with utility program Convert the drive to FAT32, which is included with Windows.
Defragment disks. Slowdown of the data exchange rate can occur as a result of fragmentation files. File fragmentation (file fragments are stored in different, remote friend from another clusters) increases over time, in the process of deleting some files and writing others.
Since the disk can store hundreds and thousands of files in hundreds of thousands of clusters, the fragmentation of files will significantly slow down access to them (magnetic heads will have to constantly move from track to track) and ultimately lead to premature wear of the hard disk. It is recommended to periodically defragment the disk, during which files are written into clusters one after the other.
Disk Defragmenter
1. To run the Disk Defragmenter program, you need to Main menu enter the command [Standard-Service-Disk Defragmenter].
2. Dialogue panel Disk selection allows you to select the disk that needs the defragmentation procedure. After pressing the button OK loops appear Disk Defragmenter.
3. The process of disk defragmentation can be visually observed by clicking on the button Intelligence... Each square corresponds to one cluster, while unoptimized, already optimized, and readable and recorded v this moment the clusters are of different colors.
Questions to Think About
1. What is the minimum volume of a file when it is stored:
- on a floppy disk;
- on a hard magnetic disk.
2. What is the sequence of placing the file File_2 from the given example on the sectors of the floppy disk?
3. Why are the values of the formatted disk capacity and the information capacity available for data recording different?
4. What is the difference between full and fast disk formatting?
5. What is the difference between the FAT16 and FAT32 file allocation tables?
6. Why is it necessary to periodically defragment hard drives?
Practical tasks
4.14. Format a floppy disk with non-standard parameters.
4.15. Calculate the cluster size of your hard disk in FAT16 system.
4.16. Use the System Information utility to determine the FAT type used on your drives.
4.17. Use the Check Disk utility to check the integrity of the file system.
4.18. Use the Disk Defragmenter utility to defragment your computer's disks.
Magnetic disks computers are used for long-term storage of information (it is not erased when the computer is turned off). In this case, in the process of work, data can be deleted, while others can be written.
There are hard disks and floppy disks. However, floppy disks are now very rarely used. Floppy disks were especially popular in the 80s and 90s of the last century.
Floppy disks(floppy disks), sometimes called floppy disks (floppy disks), are magnetic disks enclosed in square plastic cassettes measuring 5.25 "(133 mm) or 3.5" (89 mm). Floppy disks allow you to transfer documents and programs from one computer to another, store information, do archival copies information contained on the hard disk.
Information on a magnetic disk is written and read by magnetic heads along concentric tracks. When writing or reading information, the magnetic disk rotates around its axis, and the head is brought to the desired track using a special mechanism.
The 3.5-inch floppy disks have a capacity of 1.44 MB. This kind floppy disks are the most common nowadays.
Unlike floppy disks HDD allows you to store large amounts of information. Capacity of hard drives modern computers can be terabytes.
The first hard drive was created by IBM in 1973. It allowed to store up to 16 MB of information. Since this disk had 30 cylinders, divided into 30 sectors, it was designated as 30/30. By analogy with automatic rifles, which have a caliber of 30/30, this disc has received the nickname "Winchester".
A hard drive is a sealed iron box that houses one or more magnetic disks along with a read / write head assembly and an electric motor. When you turn on the computer, the electric motor spins the magnetic disk up to high speed(several thousand revolutions per minute) and the disk continues to rotate as long as the computer is turned on. Above the disc, special magnetic heads that write and read information in the same way as on floppy disks... The heads float above the disc due to its high rotation speed. If the heads touched the disc, the friction force would quickly cause the disc to fail.
The following concepts are used when working with magnetic disks.
Track- a concentric circle on a magnetic disk, which is the basis for recording information.
Cylinder Is a set of magnetic tracks located one above the other on all working surfaces of the hard drive disks.
Sector- a section of the magnetic track, which is one of the main units of information recording. Each sector has its own number.
Cluster - minimum element magnetic disk, which operates operating system when working with discs. Each cluster consists of several sectors.
