CN105930221A - Method for evaluating reliability of function reorganization strategy - Google Patents

Abstract

The invention discloses a method for evaluating the reliability of a function reorganization strategy, belonging to the field of reliability and safety. In the method disclosed by the invention, it assumes that functions born by n equipment in a function reorganization system are independent; if one equipment in the function reorganization system is failed, functions of n-1 equipment are reorganized; the reliability of the function reorganization system after function reorganization is calculated by two conditions; and thus, the reliability of the function reorganization system is obtained. According to the method disclosed by the invention, specific reliability evaluation of the function reorganization system is replaced by the function reliability; the problem that the function reorganization strategy of the function reorganization system is closely related to the function reorganization system itself can be effectively solved; a generic evaluation model is abstracted; the method disclosed by the invention can perform comparison analysis of the reorganization strategy of the function reorganization system; resources are sufficiently utilized; and the function reorganization strategy having relatively high reliability can be provided.

Description

A kind of reliability estimation method of function integrity strategy

Technical field

The present invention provides the reliability estimation method of a kind of function integrity strategy, belongs to reliability and safety (security system Engineering) field.

Background technology

Function integrity is the important step that realizes of dynamic redundancy technology, and major function is to prevent from the generation lost efficacy from having influence on to be The operation of system.Along with the synthesization of industrial engineering system, networking, complication development, to its reliability, security requirement more Come the highest.The appearance of restructuring ability the most more ensure that the reliability transmission of network.Work as system jam, or for other When the consideration of security performance makes system suffer security threat, the system with restructuring ability just can carry out function integrity in time, Recover normal to run, it is ensured that the reliable and safety of network.Particularly some provide online service or carry out real time data industry It is safe and reliable that the network of business communication the most more needs that security function recombinates, such as commercial production control system, military commanding system System etc..Therefore improve the reliability of function integrity, be possible not only to better profit from existing configuration, fault, performance, safety management Monitoring and assessment, it is also possible to increase system anti-interference, complete the ability of task.

Current system function integrity strategy is that function is relevant and experience designs, the most a set of based on network topology Complete, the instructional criterion of system.Function the Reliability modeling of recombination system can be laid particular emphasis on the reliability of system before and after restructuring The change that model occurs, and the impact that reorganization time is on system reliability.Reliability assessment to systemic-function restructuring strategy, Rarely has research.Function integrity strategy is for improving system reliability and to propose.For reaching to improve the purpose of system reliability, first Guarantee that, when meeting the condition of function integrity, function integrity strategy is able to carry out.Resource how is utilized to improve to greatest extent The reliability of system becomes the protection problem that system is properly functioning.Function integrity strategy is carried out reliability assessment and is by merit The important foundation that energy restructuring optimizes.

But it is primarily present problems with when systemic-function restructuring strategy is carried out reliability assessment: 1) the function weight of system Group policy and system itself are closely related, and are difficult to propose the assessment models of a general character；2) the function integrity strategy of system is one Individual probability event, and in different time restructuring, system reliability had different impacts, it is difficult to it is estimated.

Summary of the invention

The invention aims to solve a kind of function can the reliability assessment problem of recombination system, a kind of function is proposed Can the Reliability modeling analysis of recombination system, and then function can the restructuring strategy of recombination system be estimated.

Function integrity strategy modeling is assessed and is made hypothesis below by the present invention:

Assume that function can equipment undertakes in recombination system function be independent.Can be before recombination system function integrity in function After, each equipment provides indiscriminate function services.First function can be carried out drawing with functional independence for criterion by recombination system Point.For ease of describing, it is assumed that function can have n equipment each to undertake the function of correspondence by recombination systemIf certain Individual device fails, then n-1 functions of the equipments restructuring, the function of execution is designated as respectivelyAnd now can Complete assigned tasks.The like, if l device fails, n-l functions of the equipments restructuring, the function of execution is remembered respectively ForAnd now can complete assigned tasks, but during l+1 device fails, this function can recombination system System cannot be carried out function integrity and completes assigned tasks, and now function can lose efficacy by recombination system.In the present invention, title function can recombination system System remain to when device fails by functions of the equipments recombinate assigned tasks probability for recombinate reliability.

The reliability estimation method of a kind of function integrity strategy that the present invention provides, without loss of generality, it is considered to the feelings of l=1 Condition, l > 1 can be with iterative analysis.As l=1, namely requirementRemain to the probability keeping normally working.Due to merit Can restructuring ensure that originalFunction is required to perform, thus exists and specify function k_iAnd k_j, i ≠ j, once function Can certain equipment of recombination system when t lost efficacy, the two function is merged into a functionAnd by function k_iOr function k_j Corresponding equipment performs, and remaining n-2 equipment performsIn remaining function.Thus, affecting function can recombinate Inefficacy two kinds of situations of existence of reliability model after systemic-function restructuring:

The first situation is that the equipment lost efficacy undertakes function k_iOr function k_j；

Probability P the most now₁For:

$P_1=C_2^1{R}^{n-2}\left(t\right){\∫}_0^{t}f\left(x\right)R\left(x\right)R^{\′}(t-x)dx---\left(1\right)$

Wherein it is assumed that the Reliability Function of all devices is identical, being R (), corresponding failure dense function is f (·).The Reliability Function of the equipment undertaking multiple function after function integrity is R'(), t is task time.

The second situation is that the equipment lost efficacy does not undertakes function k_iThe most do not undertake function k_j；

Probability P the most now₂For:

$P_2=C_{n-2}^1{R}^{n-3}\left(t\right){\∫}_0^{t}f\left(x\right)R^2\left(x\right)R^{\′}(t-x)R(t-x)dx---\left(2\right)$

Lower surface analysis restructuring reliability.Assuming that event A is function can complete assigned tasks by recombination system, it is assumed that event B is that function can be recombinated by recombination system generating function, namely function can have equipment fault in recombination system.Thus restructuring reliability R_S T () is represented by:

$R_S\left(t\right)=P\left(A\right|B)=\frac{P(A\∩B)}{P\left(B\right)}---\left(3\right)$

Probability, P (A ∩ B) that wherein P (A | B) occurs for event A in the case of occurring in event B are event A and thing B Simultaneous probability.

From formula (1) and the definition of formula (2),

P (A ∩ B)=P₁+P₂ (4)

And probability of happening P (the B)=1-R that recombinatesⁿ(t), RⁿT () is the probability that t n equipment normally works.Thus according to Formula (3) can obtain:

$\begin{array}{c}{R}_S\left(t\right)=\frac{P(A\∩B)}{P\left(B\right)}=\frac{P_1+P_2}{P\left(B\right)}\\ =\frac{C_2^1{R}^{n-2}\left(t\right){\∫}_0^{t}f\left(x\right)R\left(x\right)R^{\′}(t-x)dx+C_{n-2}^1{R}^{n-3}\left(t\right){\∫}_0^{t}f\left(x\right)R^2\left(x\right)R^{\′}(t-x)R(t-x)dx}{1-R^n\left(t\right)}\end{array}---\left(5\right)$

The reliability estimation method of a kind of function integrity strategy that the present invention provides, has an advantage in that:

(1) function can be divided by recombination system by the present invention from the angle of functional independence, by the reliability generation of function Reliability assessment for concrete system, it is possible to efficiently solve that the function integrity strategy and system of system itself be closely related asks Topic, takes out the assessment models of a general character.

(2) present invention Reliability modeling analysis to function integrity system, it is possible to efficiently solve the function integrity of system In different time restructuring system reliability had and different affect problem, it is simple to function integrity system is carried out reliability assessment.

(3) present invention can be analyzed for the restructuring strategy of function integrity system, makes full use of resource, proposes more The function integrity strategy of high-reliability.

Detailed description of the invention

Below in conjunction with embodiment, the present invention is described in further details.

For certain aircraft monitoring system, according to the criterion of functional independence, this system is divided six identical monitoring devices, And suppose that these six monitoring devices undertake function TB1, TB2, TB3, LG1, LG2, LG3 respectively.Once certain monitoring device occurs Fault, then allow TB2 and TB3 be carried in a monitoring device, and the function performed by faulty equipment is loaded into TB2 and TB3 and merges In rear that idle monitoring device, namely after an equipment fault, remaining five equipment execution function TB1, TB2+TB3, LG1, LG2, LG3.

For purposes of illustration only, following each monitoring device that is abbreviated is its Elementary Function code name.As initially completed the prison of function TB1 Measurement equipment is abbreviated as TB1, and by that analogy, remaining monitoring device is abbreviated as TB2, TB3, LG1, LG2, LG3.

Initial agreement based on this system, can realize function integrity, i.e. according to both after six monitoring devices break down Fixed mechanism ensure that mode of its normal work has a following two situation:

One of them fault of the first situation: TB2 and TB3；

When one of them fault of TB2 and TB3, remaining four equipment is good.The probability that four equipment normally works is R⁴。 TB2 and TB3 is of equal value, and its probability of no matter which equipment fault is the same.Illustrate as a example by TB2 below:

If system specified operation time is t (t=8), within any time of 0-t, TB2 the most likely lost efficacy, and at TB2 Before inefficacy, TB3 is normal work, and after TB2 lost efficacy, TB3 and TB2 unites two into one, and after now merging, reliability is that R ' is (right Reliability R after merging ', it will be assumed that R ' (t)=α R (t), wherein α is for merging coefficient, and R (t) is the reliable of monitoring device Degree function).Then this system can keep the probability normally worked to be after this kind of fault occurs:

$P_1=2\×\frac{R^4\left(t\right){\∫}_0^{t}f\left(x\right)R\left(x\right)R^{\′}(t-x)dx}{1-R^6\left(t\right)}$

R⁶T () is in t, the probability that six equipment normally works.

The second situation: one of them fault of TB1, LG1, LG2 and LG3

TB2 and TB3 normally works, one of TB1, LG1, LG2 and LG3 fault, and TB1, LG1, LG2 and LG3 are of equal value, regardless of which One its probability of fault is the same.Illustrate as a example by TB1 below:

Within any time of 0-t, TB1 the most likely lost efficacy, and before TB1 lost efficacy, TB2 and TB3 the most normally works, when After TB1 lost efficacy, TB2 and TB3 merges, and monitoring device idle after merging undertakes the work of TB1.Then there is this kind in this system The probability that can keep normal work after fault is:

$P_2\left(t\right)=4\×\frac{R^3\left(t\right){\∫}_0^{t}f\left(x\right)R{\left(x\right)}^{2}R(t-x)R^{\′}(t-x)dx}{1-R^6\left(t\right)}$

In sum, being capable of the probability of function integrity after a certain device fails for this system is:

$R_S\left(t\right)=2\×\frac{R{\left(t\right)}^4{\∫}_0^{t}f\left(x\right)R\left(x\right)R^{\′}(t-x)dx}{1-R^6\left(t\right)}+4\×\frac{R^3{\∫}_0^{t}f\left(x\right)R{\left(x\right)}^{2}R(t-x)R^{\′}(t-x)dx}{1-R^6\left(t\right)}$ 。

Claims (1)

1. the reliability estimation method of a function integrity strategy, it is characterised in that:

Assume that function can equipment undertakes in recombination system function be independent, function can before and after recombination system function integrity, Each equipment provides indiscriminate function services；First function can be divided with functional independence for criterion by recombination system；False If function can have n equipment each to undertake the function { k of correspondence by recombination system₁,k₂,…,k_n, if l device fails, N-l functions of the equipments restructuring, the function of execution is designated as respectivelyAnd now can complete assigned tasks, but l During+1 device fails, this function can cannot be carried out function integrity and complete assigned tasks by recombination system, and now function can weigh Group system lost efficacy；Function can remain to when device fails in recombination system recombinated assigned tasks by functions of the equipments Probability is restructuring reliability；

As l=1, namely requirementRemain to the probability keeping normally working, there is appointment function k_iAnd k_j, i ≠ J, i=1,2 ..., n, j=1,2 ..., n, can certain equipment of recombination system lose efficacy in t once function, the two merit A function can be merged intoAnd by function k_iOr function k_jCorresponding equipment performs, and remaining n-2 equipment performs { k₁, k₂,…,k_nRemaining function in }；Thus, affecting function the inefficacy of reliability model can exist two after recombination system function integrity The situation of kind:

The first situation is that the equipment lost efficacy undertakes function k_iOr function k_j；

Probability P the most now₁For:

$P_1=C_2^1{R}^{n-2}\left(t\right){\∫}_0^{t}f\left(x\right)R\left(x\right)R^{\′}(t-x)dx---\left(1\right)$

Wherein it is assumed that the Reliability Function of all devices is identical, being R (), corresponding failure dense function is f ()；Merit Can restructuring after undertake multiple function equipment Reliability Function be R'(), t is task time；

The second situation is that the equipment lost efficacy does not undertakes function k_iThe most do not undertake function k_j；

Probability P the most now₂For:

$P_2=C_{n-2}^1{R}^{n-3}\left(t\right){\∫}_0^{t}f\left(x\right)R^2\left(x\right)R^{\′}(t-x)R(t-x)dx---\left(2\right)$

Assuming that event A is function can complete assigned tasks by recombination system, it is assumed that event B is that function can recombination system generation merit Can recombinate, namely function can have equipment failure in recombination system, thus restructuring reliability R is expressed as:

$R=P\left(A\right|B)=\frac{P(A\∩B)}{P\left(B\right)}---\left(3\right)$

Defined by formula (1) and formula (2) and know,

P (A ∩ B)=P₁+P₂ (4)

And probability of happening P (the B)=1-R that recombinatesⁿ(t), RⁿT () is the probability that t n equipment normally works, thus according to formula (3):

$\begin{array}{c}{R}_S\left(t\right)=\frac{P(A\∩B)}{P\left(B\right)}=\frac{P_1+P_2}{P\left(B\right)}\\ =\frac{C_2^1{R}^{n-2}\left(t\right){\∫}_0^{t}f\left(x\right)R\left(x\right)R^{\′}\left(t-x\right)dx+C_{n-2}^1{R}^{n-3}\left(t\right){\∫}_0^{t}f\left(x\right)R^2\left(x\right)R^{\′}\left(t-x\right)R\left(t-x\right)dx}{1-R^n\left(t\right)}\end{array}---\left(5\right).$