In accordance with GOST 27.002 - 89, redundancy is the use of additional funds and (or) capabilities in order to maintain the operable state of the object in case of failure of one or more of its elements. So the reservation is effective method increasing the reliability of the object by introducing redundancy. In turn, redundancy is additional means and (or) capabilities that are superminimal necessary for the object to perform the specified functions. The introduction of redundancy ensures the normal functioning of the object after the occurrence of a failure in its elements.

Redundancy methods are divided according to the type of redundancy, the method of connecting elements, the multiplicity of redundancy, the method of switching on the reserve, its mode of operation and recoverability (Fig. 7.1).

Additional tools and capabilities for redundancy include elements introduced into the system structure as backup, functional and information tools and capabilities, the use of excess time and load capacity reserves. According to the type of additional funds, the following types of reservation are distinguished.

Functional redundancy is a redundancy in which a given function can be performed in various ways and technical means. For example, to implement the function of transmitting information to the ACS, radio channels, telegraph, telephone and other means of communication can be used; therefore, in this case, the usual average reliability indicators (mean time between failures, the probability of failure-free operation, etc.) become uninformative and not suitable enough. The most appropriate for assessing functional reliability are the probability of performing a given function, the average time to perform a function, and the availability factor for performing a given function.

Information redundancy is redundancy using information redundancy. Examples of such redundancy are: multiple transmission of the same message over a communication channel; the use of various codes in the transmission of information over communication channels that detect and correct errors that appear as a result of equipment failures and the influence of interference; the introduction of redundant information symbols in the processing, transmission and display of information. The excess of information makes it possible, to some extent, to compensate for the distortions of the transmitted information or to eliminate them.

Temporary reservation is associated with the use of time reserves. It is assumed that the time required for the object to perform the required work is obviously more than the minimum required. Time reserves can be created by increasing the productivity of the object, the inertia of its elements, etc.

Load redundancy is redundancy using load reserves. It consists in ensuring optimal reserves of the ability of the elements to withstand the loads acting on them or in introducing additional protective or unloading elements into the system to protect some of the main elements of the system from the loads acting on them.

These types of redundancy can be applied either to the system as a whole, or to its individual elements or their groups. In the first case, the reservation is called general, in the second - separate. The combination of different types of reservation is called mixed.

According to the method of switching on the reserve, a distinction is made between permanent and dynamic redundancy.

Permanent redundancy is carried out without restructuring the system structure in the event of a failure of its element. This type of redundancy is characterized by the fact that in the event of a failure of the main element, no special devices are required to activate the reserve element, as well as interruptions in operation (Fig. 7.2 and 7.3).

Dynamic redundancy is carried out with the restructuring of the system in the event of a failure of its element.

Permanent redundancy is a parallel or series connection of elements without the use of switching devices; dynamic redundancy requires switching devices that respond to element failures.

Often, dynamic redundancy is a replacement redundancy, in which the functions of the main element in the event of its failure are transferred to the backup. Redundancy with the inclusion of reserve replacement (Fig. 7.4 and 7.5) has the following advantages:

Does not violate the mode of operation of the reserve;

It preserves the reliability of the backup elements to a greater extent, since during the operation of the main elements they are in a non-operating state;

Allows you to use a backup element in circuits for several main elements.

A significant disadvantage of replacement redundancy is the need for switching devices. With separate redundancy, the number of switching devices is equal to the number of main elements, which can significantly reduce the reliability of the entire system. Therefore, it is advisable to reserve large nodes or the entire system by replacement, while the reliability of switching devices must be sufficiently high.

A common type of replacement redundancy is a sliding redundancy, in which a group of the main elements of the system is backed up by one or more backup elements, each of which can replace any failed main element in this group (Fig. 7.6).

Depending on the mode of operation of the reserve elements before the failure of the main element, the following types of reserve are distinguished:

Loaded (one or more reserve elements are in the mode of the main element);

Lightweight (one or more backup elements are in a less loaded mode than the main element);

Unloaded (one or more backup elements are in unloaded mode until they start performing the functions of the main element).

Majority reservations (using “voting”) are widely used in control systems. This method is based on the use of an additional element, called the majority or logical (Fig. 7.7). Thanks to this element, it is possible to compare signals from elements that perform the same function. If the comparison results match, they are transferred to the output of the device.

On fig. 7.7 shows the majority reservation according to the “2 out of 3” principle, i.e. any two matching results out of three are considered true and pass to the output of the device. According to this principle, many schemes of subsystems of control and protection systems (CPS) are built. The main advantage of the majority redundancy is to ensure an increase in reliability in case of any types of element failures and an increase in the reliability of information-logical objects.

Reserve elements differ in the level of reliability. The elements of the loaded reserve have the same level of reliability (reliability, durability and persistence) as the main elements of the object they reserve, since the resource of the reserve elements is consumed in the same way as the main ones. Light reserve elements have more high level reliability, since the intensity of resource consumption of reserve elements until they are switched on instead of failed elements is much lower than that of the main ones. With an unloaded reserve, the resource of reserve elements begins to be consumed practically only from the moment they are switched on instead of failed elements.

According to the method of reserving an object (element of an object), there are general and separate reservations. With general reservation, the object is reserved as a whole, instead of one object, the simultaneous operation of two or more objects of the same type or similar in terms of their functions is provided. This method is quite simple; it is widely used for redundancy of the most critical systems. With separate reservations, individual elements of an object or groups of elements that are usually embedded in an object are reserved; Separately, both individual elements of the system and its rather large parts (blocks) can be backed up.

Dynamic redundancy can be separate and common, allows the use of backup elements not only in loaded, but also in lightweight and unloaded backup, which, in turn, allows you to save the resource of backup elements, increase the reliability of the electrical system as a whole and reduce energy consumption.

When redundant by substitution, sliding redundancy can be used, which ensures the required reliability of the system at low cost and a slight increase in its weight and dimensions. The disadvantages of dynamic redundancy by replacement include the need to use switching devices, interruptions in operation when switching to redundant elements, as well as a search system for a failed element or block, which reduces the reliability of the entire redundant system. It is expedient to use this method for redundancy of sufficiently large functional units and blocks of complex electrical systems.

Permanent redundancy, which involves the permanent connection of backup elements with the main ones, is simple. This type of redundancy does not require switching devices. In case of failure of the main element, the system continues to operate normally without interruption and switching. The disadvantages of permanent redundancy include an increased resource consumption of redundant elements and a change in the parameters of a redundant node in case of element failure. This type of redundancy is used in critical systems for which even a short interruption in operation is unacceptable, as well as when redundant relatively small elements - nodes, blocks and elements of SA electronic equipment (resistors, capacitors, diodes, etc.).

The redundancy of the radio elements included in the block, the failure of which can lead to especially dangerous consequences, is carried out taking into account the possibility of both short circuits and element breaks. Redundancy in case of element breaks is performed by parallel connection, in case of short circuits - by serial connection, assuming that the element fails, but the electrical circuit of other elements connected in series with it is not violated. For example, permanent separate redundancy of a diode with a loaded reserve in case of failure as a result of a short circuit (short circuit), open circuit or short circuit and open circuit is carried out by switching on the reserve diodes, respectively, in series, in parallel and in series-parallel to the main one (Fig. 7.8, a-c).

The general permanent backup of the VD rectifier by the loaded reserve is performed by parallel connection of the reserve; diodes in this case are used to prevent the backup rectifier current from flowing through the output circuit of the failed rectifier (Figure 7.9).

The general redundancy of the rectifier with an unloaded reserve is carried out using switch P, which receives a signal CO about the failure and sends a control signal YC to the switch QW to turn off the failed rectifier and turn on the reserve one (Fig. 7.10).

Permanent redundancy can be carried out by parallel or serial connection to the main element (system) of one or more redundant ones that perform the same functions as the main element (system). Such redundancy is used, for example, in parallel operation computers, SA blocks, resistors, as well as when diodes, break contacts, capacitors, etc. are connected in series. 7.11 shows several options for redundant capacitors.

The consequences of failure of elements with permanent redundancy in extreme cases may be a short circuit or a break in one or more elements, which must be taken into account when designing the system. To prevent these negative phenomena, limiting resistances are introduced, isolation transformers are turned on, and the tolerances of individual system parameters are increased, etc.

Currently, the following criterion is used to assess the reliability of a system: a system is considered absolutely reliable if the failure of any one element does not lead to the failure of the entire system. The implementation of this criterion in practice is carried out by element-by-element or block-by-block redundancy.

The properties of various types of redundancy can be identified by analyzing the gain in system reliability in terms of the main quantitative characteristics. Let us evaluate the effectiveness of various redundancy methods, taking the probability and mean time to failure as quality criteria and making the following simplifying assumptions:

All elements of the system have equal reliability;

The element failure flow is the simplest;

The multiplicity of redundancy of all elements is the same.

If, under the assumptions made, the probability and mean time to failure of a non-redundant system is expressed by the formulas:

then the reliability gain of a redundant system compared to a non-redundant one will be equal to:

Based on the analysis of Fig. 7.12-7.14 we can draw the following important conclusions about the properties of redundancy.

1. Regardless of the failure rate of a non-redundant system, the failure rate of a redundant system always starts from zero. As the operating time of the system increases, the failure rate of the redundant system tends asymptotically to the failure rate of the non-redundant system. When redundant with a fractional multiplicity, the failure rate of the redundant system for certain values ​​\u200b\u200bof / can be greater than the failure rate of the non-redundant system. This means that a system with fractional redundancy applied may be less reliable than a non-redundant system.

2. From fig. 7.15 it can be seen that there is such a critical value of the operating time r, above which redundancy with a fractional multiplicity is inappropriate.

3. The gain in reliability in terms of the probability of failure is the greater, the lower the failure rate of the non-redundant system, i.e., the more reliable the system is redundant. This is the main contradiction of redundancy in general. It leads to the fact that a high redundancy ratio is required to improve the reliability of long-term systems.

4. With any redundancy, except for sliding, a significant increase in the mass of the system leads to a less significant increase in the mean time to failure.

"29552"

In recent months, publications on the topic of the imminent end of the world have flashed in the media, even the exact date is called - December 21, 2012 (12/21/12). The meaning of all these messages is the same: on the specified date, the alleged 99-year lease of the US Federal Reserve money printing press expires ...

How It Was: The passage of the Federal Reserve Act in 1913

The term is counted from December 21, 1913, when the Federal Reserve Act was passed in the US Congress, which provided for the creation of central bank under the name "US Federal Reserve System" and gave this institution the authority to issue money in the country. Further, the authors of publications on the topic "12/21/12." the following assumptions are made:

1) on the specified day the "printing press" of the FRS stops its work;

2) in short time the US and world economy, dependent on dollar emission, will begin to experience a shortage of liquidity (money); this will lead to the disorganization of economic life at all levels, a sharp drop in production and consumption, and a sharp aggravation of social tension;

3) on the basis of economic contradictions and social tension, armed conflicts will begin at all levels; at the global level is inevitable World War using weapons of mass destruction.

That is, in other words, on December 21, the chain of events leading to the apocalypse will only begin, and the end of the world will come a little later.

What does "printing press lease" by the Federal Reserve mean? To use a stricter vocabulary, in less than three months, the powers granted by the US Congress in the form of a license or concession (in English - chart) expire to the specified private institution. And the main of these powers is the right to issue legal tender - the US dollar. I will try to clarify the issue of the terms of office of the Federal Reserve, and at the same time give my own vision of the future of this institution.

So, in December 1913, the Federal Reserve Act of 1913 was passed. By the way, the chronology of events is as follows:

c) on the same day, December 23, 1913 (literally an hour after the vote in the Senate) - the signing of the law by US President W. Wilson and the entry into force of the law.

Why December 21 appears in the mentioned publications about the “end of the world” is not at all clear. Apparently, the authors of the publications liked the beautiful combination of numbers: 12/21/12. Looks like cabal.

About the terms of "leasing a printing press"

Section 4 of this law (as passed in 1913) states that the powers of the Federal Reserve Banks that make up the Fed (there are twelve in total) are granted for a period of 20 years, i.e. until the end of 1933. At the same time, it was stipulated that the powers could be withdrawn even earlier than the specified period, if the US Congress adopted on this occasion special law or if the Federal Reserve violates the provisions of the 1913 Act (in the original, the following wording: " To have succession for a period of twenty years from its organization unless it is sooner dissolved by an Act of Congress, or unless its franchise becomes forfeited by some violation of law. // P.L. 63-43, 38 STAT. 251, 12 USC 221). There is no mention of any 99 years of "rent" in the 1913 law at all.

In the history of America, by the time the FRS was established, there was a certain tradition, if you like, to issue a license (charter, charter - chart) to the central bank for exactly 20 years. The first prototype of a central bank there was the Bank of America. Then - the First Bank of the United States. Then - the Second Bank of the United States. The Bank of America received a charter in 1781, but the Founding Fathers quickly realized the threat to the gains of the American Revolution that institution posed, and four years later they withdrew the charter. The first Bank of the United States was chartered in 1791 and operated for twenty years. However, there was no renewal of the charter. Finally, the Second Bank of the United States received a charter from Congress in 1816, but it was withdrawn early from the bank in 1834. This was done not without difficulty and risk to the life of the American president. Andrew Jackson. After that, America lived for eight decades without a central bank, although the bankers all this time made constant attempts to impose this institution on the American people.

Many sources say that a long time ago the Fed received indefinite powers. It is right. Only it is not always precisely determined when the Federal Reserve will switch to an indefinite lease of the printing press. This is really not easy to figure out, because over the nearly century-old existence of the Fed in the United States, a total of about 200 laws were passed that made changes and amendments to the Federal Reserve Act of 1913. The United States has a set of laws called the United States Code (U.S.C.). It reflects all current American laws, taking into account amendments and additions made at different times. This code also has a valid this moment version of the Federal Reserve Act.

For some reason, the moment of the Fed's transition to the "perpetual lease of the printing press" is often linked to the arrival of White House President Franklin Roosevelt (inaugurated in January 1933). Allegedly, the first thing he did was to push through Congress (in a secret meeting) an amendment that gave the Federal Reserve unlimited powers. One of the most popular conspiracy publications of this kind is the article by Wayne Krautkramer. The Federal Reserve - Its Origins, History & Current Strategy // CureZone.com // 11.11. 2010). He writes of the fate of the 1913 law: “Section 341, Part 2. The law is in effect for 20 years unless it is repealed by Congress in that time, or unless the Fed's license is revoked due to a violation of the law. The Federal Reserve has been given a lifespan of 20 years! That is, until 1933. Who was president at this time? Franklin Roosevelt, of course. There was no shutdown of the Federal Reserve.”

However, Franklin Roosevelt is credited with a non-existent credit to the Federal Reserve bankers. In fact, back in 1927, a law was passed that lifted temporary restrictions on the right of the Federal Reserve to issue money. The original text of the law says: "To have succession after February 25, 1927, until dissolved by Act of Congress or until forfeiture of franchise for violation of law." Very similar to the wording of the 1913 law, only without the phrase "for a period of twenty years" (this provision is reflected in the US code:

12 U.S.C. § 341. // http://www.law.cornell.edu/uscode/us...1----000-.html).

Modern passions around the Fed

Importantly, however, the fact that the Federal Reserve Act retained a provision on the right of the US Congress to deprive the Federal Reserve of powers on one of two grounds:

a) the passage by Congress of a law on such deprivation (even with the full implementation of the Federal Reserve of all requirements of the law);

b) violation by the Federal Reserve of the provisions of the law of 1913.

For me personally, there is no doubt that the Federal Reserve should have been stripped of its powers long ago for gross violations American law. One of the most striking examples is the clandestine operation of issuing huge loans to the largest private banks during the last financial crisis. A partial audit by the Fed showed that the amount of such loans exceeded $16 trillion. It is noteworthy that among the recipients - a large number of non-US banks. And the adoption of a decision on the issuance of loans by the Federal Reserve to non-residents (foreign organizations) is possible only with the consent of Congress. It is also noteworthy that all this was done in secret from the "servants of the people" - congressmen and senators. So far (more than a year has passed since the publication of the results of this audit), the i's have not been dotted. Fed Chairman Ben Bernanke did not provide intelligible explanations about the mysterious operations.

There is no particular mysticism around the activities of the Federal Reserve. There is a tense confrontation between world bankers and the American nation. So far, the bankers manage to defend and maintain their positions. Although the indignation of the people about the openly corrupt and gangster activities of the bankers reached its climax during the entire existence of the Federal Reserve since 1913. In the summer of 2012, stunning news spread throughout the world media: on July 25, the US Congress voted by a majority vote in favor of the bill on the audit of the Federal Reserve (Audit the Fed Bill) initiated by the legendary congressman Ron Paul. There were 327 votes in favor and 98 against.

Note that the bill provides full Fed audit, including verification of the conformity of the status of this institution with the American constitution. Recall that according to the US constitution, the inalienable right to print money belongs only to the people and their chosen Congress. True, today a fairly large number of Americans have already made a “discovery” for themselves: 99 years ago, this right to print money was leased to a private corporation. Moreover, the American people still do not really know who it belongs to. A number of meticulous researchers (for example, Eustace Mullins, who wrote the book "Secrets of the Federal Reserve" - ​​Secrets of the Federal Reserve) prove that among the main shareholders of the Fed are the largest non-US banks.

By the way, neither Ron Paul nor other tough and professional opponents of the FRS from the US Congress have ever mentioned that the lease term of the “printing press” allegedly expires at the end of this year. I think they know every comma in the Federal Reserve Act. The Federal Reserve audit bill has not yet become law, as the shareholders of this private corporation are furiously resisting (they are now trying to "bury" the bill in the US Senate). Nevertheless, voting in Congress is a much more important event in American (and even world) life than the mystical numbers "12/21/12".

Is it not for this reason that the Council for Operations on open market The FRS ("council of wise men") hastened to decide on the start of the third stage of the so-called? Behind this term lies a large-scale distribution of money by the Federal Reserve to American private Wall Street banks under the guise of "fighting unemployment" ($40 billion a month in the form of redemption of "junk" mortgage papers from banks' portfolios). Bankers are in a hurry to squeeze everything possible out of the "printing press". What if tomorrow they will take away the rent for this “machine”?

At the same time, the FRS bankers are frantically looking for cardinal solutions for their salvation. Their aggressiveness and adventurism sharply increases. Unleashing wars outside of America is an important strategic move, which, in their opinion, will help to turn the attention and indignation of American lawmakers and the American people with the Fed to other targets (terrorists, Islamists, dictators, etc.). And by dragging America into a permanent war with the rest of the world, the bankers expect to make good money on this. The implementation of the above-mentioned strategic plan of the owners of the Fed is a direct path to the global apocalypse.

It is possible and necessary to deprive the Federal Reserve of its powers without waiting for the mystical date 12/21/12. American law not only allows, but directly requires it. Ron Paul explains this very convincingly in his book "Do away with the Federal Reserve"(End the Fed), which became a bestseller in the US. Doing away with the Federal Reserve is not only in the interests of America, but of the whole world ...

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Olya, I liked your article so much, it is like a memory about how I studied batik. And I, like you, first met him in 1992, I was 16 years old. Precisely with such tubes for the reserve I worked. 🙂

Please tell me, is it possible to use the gamma reserve if it has expired? It is thick, but if you dilute it with gasoline?

Answers:
January 29th, 2012 at 18:40

It is best to try on a separate patch. Draw a bagel, as it dries - try with water.
I now have a gamma from 2007 - it's normal. Has deteriorated - if it has become very liquid. And thick - not scary, dilute with gasoline. The main thing is not to keep the reserve below 0 degrees. After freezing, it is not suitable. I'm waiting for spring to order online :)

Olesya says:
March 12th, 2012 at 4:49 am

please give the address of the online store with delivery in the Russian Federation COD, WHERE IT IS POSSIBLE TO ORDER PAINT ON FABRIC AND STAINED GLASS TRANSPARENT

The sharp and persistent smell of a reserve for cold is really tin)), paraffin is much more comfortable ..

Olga, thanks for the helpful articles.
"""To create thin colored lines, I use the usual artist. oil paint»»» Can you elaborate? If possible, please reply by email. [email protected]
Thank you in advance!

So what reserve for cold batik will not leak paint? to order online? (In our town, apart from tubes, nothing is sold). Please tell me. You won’t be able to cook on your own: the house is full of children.

And if you break the spout of a glass tube, can you use it after that?

I bought the “gamma” reserve composition, and it turned out to be very liquid, spreads over the fabric, left it open for the night, then for a day, for two, it is still liquid like water. what to do with him? I didn’t buy it before, I took it from a friend, she cooked it herself. maybe not good quality. aren't they all liquid? can it be mixed with rubber glue?

Please tell me, the reserves have not changed, that is, the petrol-based reserve is still being sold, it is not washed off in water, right? it’s just that once upon a time I bought Gamma batik paints, in the instructions it was written that the paints needed to be steamed, now, the same gamma batik, it says that they need to be ironed. And what about the reserve, it has not changed?

The reserve that was in the gamma set - it has not changed. And it's not bad at all, apart from its smell. It is not washed off in water, it dissolves with gasoline. And with the same reserve, you can paint with paints that are fixed with an iron. However, those paints that are steamed are also on sale now 😉 New reserves have appeared that dissolve with water. When painting, it also dissolves and wonderfully spoils the work, because the paint does not hold well. I do not recommend 😉

Tell me, Olga, what to do if the paint sometimes leaks through the reserve line while working with batik, after applying the reserve. What are the main secrets of a good quality backup line? Thanks

Tell me, Olga, please, is it possible to add oil paint to the reserve, which is water-based, to paint it? Since I can’t use odorous reserves from allergies. Thank you.

Daria, you can't. Oil paint Do not dilute with water. You can color the water-soluble reserve with fabric paint. Which is thicker for dark fabrics. But at the same time, its resistance to paint transmission will decrease. It is already not high for water-based reserves. Draw a wider line then. And it’s better after painting to go through the lines with a colored outline already ready. After all, they are water-based and you will not have allergies 🙂

Reservation types

There are four main types reservations:

• Hardware redundancy, such as redundancy
• Information redundancy, for example - methods for detecting and correcting errors
• Temporary redundancy, such as alternative logic methods.
• Software redundancy, the use of independent functionally equivalent programs

Redundancy in technical systems

Power supply redundancy (duplication).

Reservation- a method of improving the reliability characteristics of technical devices or maintaining them at the required level by introducing hardware redundancy by including spare (reserve) elements and links that are additional compared to the minimum necessary to perform the specified functions under given operating conditions.

Redundancy is widely used at hazardous production facilities, in many cases its necessity is dictated by the requirements of industrial safety or government rules and standards. Some technical devices initially provide for redundancy in their design, for example, indirect-acting safety valves - impulse safety devices. Redundancy is also widely used in military equipment.

Redundancy is one of the main principles for ensuring the safety of nuclear power plants, along with physical separation And variety of equipment responsible for the practical implementation of the most important single failure principle. Systems that are important for the safety of nuclear power plants (that is, very many) have a three-fold redundancy, and in the latest Russian projects implemented during the construction of the Tianwan NPP in China - a four-fold redundancy.

Elements of the minimized structure of the device, ensuring its performance, are called basic elements; reserve elements called elements designed to ensure the operability of the device in the event of failure of the main elements. Redundancy in technological systems is classified according to a number of criteria, the main of which are the level of redundancy, the multiplicity of redundancy, the state of the reserve elements until they are put into operation, the possibility of joint operation of the main and reserve elements with a common load, the method of connecting the main and reserve elements. In a redundant product, a failure occurs when the main device (element) and all backup devices (elements) fail. A group of elements is considered redundant if the failure of one or more of its elements does not disrupt the normal operation of the circuit (system), and the remaining serviceable elements perform the same specified function. This reservation is called functional redundancy.

• Reservation ratio- the ratio of the number of reserve elements to the number of main elements of the device. The redundancy rate is usually denoted m. For example, if m=3, this means that: the main device is one, the number of backup devices is three, and the total number of devices is (three plus one) four. If m=4/2, this means fractional redundancy, where the number of standby devices is four, the number of primary devices is two, and the total number of devices is six. You can't cancel a fraction because if m=4/2=2, then this is an integer redundancy, in which the number of backup devices is two, the main one is one, and the total number of devices is three!
  One time reservation is called duplication.

The use of a light or unloaded reserve makes it possible to reduce the energy consumption consumed by the redundant system and increase the reliability of the equipment (T av p unload > T av p reg > T av p load), since the reliability of backup devices is higher than that of the main ones. However, it should be borne in mind that a break for switching from the main device to the backup is not permissible in all schemes.

• Depending on the scale and accepted unit of reservation, there are:
  • general reserve, at which the reserve is provided in case of failure of the object as a whole, and
  • separate (element-by-element) reserve, in which separate parts of the object (blocks, nodes, elements) are reserved.
    A special case of element-by-element redundancy is sliding a reservation that can be used if you reserve a group of identical elements.
  • A combination of general and separate reservation is also possible - the so-called mixed reservation.

The expediency of using redundancy is determined by the following factors:

• the initial level of reliability of components;
• set operating time;
• the presence of an effective control system and the frequency of prevention;
• the possibility of using less redundant methods to improve reliability.

The analysis of redundant systems shows that the failure rate of a redundant system increases rapidly over time, although the failure rate of a non-redundant system does not depend on time, which implies that there comes a point in time after which the use of a redundant system does not justify itself. Therefore, if you do not take into account the features of system prevention, then it is advantageous to use redundancy for systems of short-term use, and for critical systems and systems of long-term use, use other methods to increase reliability. Redundancy methods that are effective for continuous-type digital systems may be of little use for systems with analog-type devices, for which, due to the absence of mutual influence of the main and backup channel, a replacement redundancy scheme is preferable. Thus, the existing variety of systems makes it difficult to build common design approaches and uniform requirements for reliability.

It is customary to evaluate the redundancy efficiency using reliability improvement factor γ, which is determined by the reliability indicators from the ratios:

γ p = P(t) R / P(t) γ Q = Q(t) / Q(t) R

where P(t) R, Q(t) р, - and failure probability for a redundant system,

P(t) And Q(t) - probability of failure And failure probability for a non-redundant system.

General system redundancy

With general redundancy, the entire system is backed up. General redundancy, depending on the method of switching on redundant devices, can be divided into permanent redundancy and replacement redundancy, in which redundant products replace the main ones only after a failure. With a general permanent redundancy, the backup devices are connected to the main one during the entire time of operation and are in the same mode of operation as it is.

Permanent reservation

The benefits of permanent shared redundancy include:

• the relative simplicity of constructing circuits;
• the absence of even a short break in work in case of failure from one to m-1 elements of the system;
• the absence of additional connected elements that reduce the overall reliability of the circuit.

The obvious disadvantages of a loaded reserve, in addition to an increase in the dimensions and mass of the system, are an increased energy consumption, as well as the fact that the reserve elements “age” simultaneously with the main elements of the system. In the case of a general redundant system, a complete composition of the recorded elements is required. With general permanent redundancy, only the loaded reserve can be used.

Characteristics for the case of a redundant system with total permanent redundancy

The probability of failure-free operation of a redundant system with a total constant redundancy with an integer multiplicity is calculated by the formula:

,

where P(t

P(t) = e-λ t R- probability of failure-free operation

non-redundant system with an exponential law of distribution of reliability,

m

where T cf p is the mean time between failures of the redundant system,

T cf - mean time between failures of a non-redundant system.

m= 1, we get:

, .

Thus, with duplication (one main device is backed up by one backup device), the mean time between failures increases by 1.5 times.

Reservation by replacement

When redundant by replacement, the backup device is included in the operation of the system using automatic devices or manually by a human operator. With automatic switching, extremely high reliability of the switching elements is required. With a large number and low reliability of these additional elements included in a redundant system, its reliability may decrease compared to the reliability of a non-redundant system. In addition, there is a short break, while switching to backup devices. When manually replacing failed elements, the switching time increases, but the reliability of the human operator performing the switching can be taken as a unit in calculations.

When using a loaded reserve, spare reserve elements are in the same mode of operation as the main elements (regardless of whether they participate in the operation of the circuit or not), and if the main and reserve elements are identical, then their failure rates are the same and the reliability of the main and of the redundant device is the same, and therefore, if the reliability of automatic switching devices is not taken into account, the reliability characteristics are calculated using the same formulas as for the general permanent redundancy.

When using an unloaded reserve, spare reserve elements are completely disabled until they are put into operation of the system. In this case, the redundant devices have the highest reliability compared to the main elements, so the general replacement redundancy using an unloaded reserve provides the best reliability for the case of a general redundancy.

Characteristics for the case of general redundancy by replacement using an unloaded reserve. ,

where P(t) р - probability of non-failure operation of the redundant system

P(t) is the probability of non-failure operation of a non-redundant system,
m- redundancy rate.

where P(t) p and P(t) p - mean time between failures of redundant and non-redundant systems,

T av p and T av - mean time between failures of redundant and non-redundant systems, m- redundancy rate.

For the simplest case, when m= 1, we get:

, .

Thus, when using an unloaded reserve, the mean time between failures increases at least twice.

Separate reservation

With a separate method of redundancy, an individual reserve is introduced for each part of the non-redundant system. Separate reservation is common and substitution. With separate substitution, a system failure can occur only when the failure occurs twice in a row in the same device (m=1), which is unlikely. To assess the reliability with separate redundancy, a complex, specific mathematical apparatus is used. In general, mathematical analysis shows that the highest reliability indicators can be obtained in the case of building systems using separate redundancy by replacing an unloaded reserve.

Redundancy in biological systems

• Animals that are close to the beginning of food chains use a reservation mechanism that ensures the reproduction of the species - numerous offspring. Herbivores, which are food for predators, usually have more numerous offspring than predators.
• The human body gives a fairly large number of examples of the reservation of external and internal organs. Examples of duplication of external organs are eyes, ears, hands, nostrils. An example of the reservation of internal organs of a person is the duplication of the gonads, the kidneys. Reservation creates new functionality. Duplication of the eyes (separated by a certain distance) allows you to implement stereoscopic vision, that is, to determine the distance to the object, duplication of the ears - to determine the direction to the sound source (binaural effect).

The applied science of bionics deals with the study of redundancy in biological systems.

Redundancy in organizational systems

System Failure Probability Calculation

Each element of redundancy reduces the probability of node failure in accordance with the formula:

, where:

The formula assumes independent failure of the elements. This means that the probability of failure of element i is the same both for a failed element j and for a good one for all ≠ . This formula is not always applicable, for example, in the case of parallel connection of two power supplies, the probabilities differ.

It is also assumed that one (any) element is enough for the node to work. In the event that for the operability of the node it is necessary to have elements from the available ones, the probability of failure is equal to:

Provided that all elements have the same probability of failure.

The number of combinations of is equal to the binomial coefficient

The model assumes that failed elements are not replaced, and the redundancy device has a zero probability of failure.

see also

Notes

Links

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Synonyms:

See what "Reservation" is in other dictionaries:

reservation- The use of additional devices and systems or elements of devices and equipment systems so that in the event of a failure of one of them to perform the required function, another device (or element of the device) is available, ready ... ...

reservation- me, cf. reserver. Action by value ch. reserve. Reservation in print printing. TE 1933 21 16. Lex. Toll App. 1866: reservation... Historical Dictionary of Gallicisms of the Russian Language

In technology, a method of increasing the reliability of a technical object by introducing additional devices, nodes and connections into its composition, designed to quickly replace (automatically or manually) failed similar elements ... ... Big Encyclopedic Dictionary

Preservation; fixed distribution, booking; reservation, abandonment, reservation, conservation Dictionary of Russian synonyms. reservation n., number of synonyms: 6 reservation (4) ... Synonym dictionary

Redundancy is the use of more than the minimum necessary number of elements or systems in such a way that the failure of any of them does not lead to the loss of the required function of the whole. Terms nuclear energy. Concern Rosenergoatom, ... ... Nuclear power terms

- (from lat. reservare to save) 1) saving resources in reserve, in reserve; 2) reserving the right to return to any question. Raizberg B.A., Lozovsky L.Sh., Starodubtseva E.B. Modern economic dictionary. 2nd ed., rev. M.:… … Economic dictionary

reservation 1+1- A redundancy mechanism in which traffic is duplicated in a backup channel (permanently connected). The channel connecting the platforms performs traffic switching between the working and backup channels (ITU T Y.1720). )