36 results about "Minimal cut set" patented technology

Method for computing all-terminal reliability for arbitrarily interconnected networks such as the United States public switched telephone network. The method includes an efficient search algorithm to generate minimal cut sets for nonhierarchical networks directly from the network connectivity diagram. Efficiency of the search algorithm stems in part from its basis on only link failures. The method also includes a novel quantification scheme that likewise reduces computational effort associated with assessing network reliability based on traditional risk importance measures. Vast reductions in computational effort are realized since combinatorial expansion and subsequent Boolean reduction steps are eliminated through analysis of network segmentations using a technique of assuming node failures to occur on only one side of a break in the network, and repeating the technique for all minimal cut sets generated with the search algorithm. The method functions equally well for planar and non-planar networks.

The invention discloses a power-system economic dispatching method considering power grid topology optimization. A power-system dispatching model using active power of conventional generator sets and output component states of the power grid as decision making factors is provided by incorporating the power grid topology optimization into a power-system economic dispatching model and considering the power grid topology connectivity conditions. Topological connectivity is constrained based on the minimum cutset concept in graph theory so as to judge system topological connectivity. The provided model is solved by combination of genetic algorithm and linear programming primal-dual path following interior algorithm. Conventional generator sets and power grid topology can be preset, economical efficiency of power grid operation is improved on the premise of guaranteeing safety of power grid operation, balance capacity of load power of system generation is improved, renewable energy power generation can be accepted within a larger range, abandonment of renewable energy power generation or load shedding is effectively alleviated, and technical support is provided for intelligent development for power system dispatching.

A minimal cut set based system for monitoring faults of nuclear reactors provides decision support for fault diagnosis of nuclear reactor systems and can also be applied to related fields of aviation, navigation, chemical engineering and the like. The system is mainly composed of a model analyzer, a task dispatcher, a parallel machine, a result collector, a cut set analyzer and a fault diagnostor. The system has the advantages of being high in storage efficiency, fast in calculation, easy to deploy and maintain and the like. Compared with the prior art, the system performs parallel calculation on each layer of nodes of fault trees through the parallel machine, so that the calculating speed and accuracy are improved to a large extent, and faults of nuclear reactors can be diagnosed and monitored effectively.

The present invention discloses a pipeline failure possibility evaluation method and system, wherein the evaluation method comprises the steps of establishing a failure fault tree of a to-be-evaluated pipeline, determining a top event and an elementary event, and obtaining a minimum cut set; dividing the grade of the elementary event, and obtaining the failure probability of the elementary event according to a fuzzy theory; according to the failure probability of the elementary event and the logic structure of the failure fault tree, obtaining the probability of the minimum cut set and the failure probability of the to-be-evaluated pipeline. According to the present invention, by utilizing the fault tree, the risk of the pipeline is calculated quantitatively, and the failure probability of the to-be-evaluated pipeline is obtained, so that the weak links can be searched effectively, the contingency plans and the protection measures can be made, and the safety of a pipeline system is improved.

The invention belongs to the technical field of fault analysis and relates to a modularized method for obtaining a nuclear power station fault tree top item failure probability. The method comprises the steps of: establishing a fault tree; carrying out modularization on the fault tree; converting the modularized fault tree into a BDD structure; and carrying out traversal on the BDD structure containing modules. The modularized method for obtaining the nuclear power station fault tree top item failure probability is a fault tree analysis method low in energy consumption and high in speed, the most simplified BDD structure subjected to absorption simplification is transverse, all minimal cut sets (MCSs) are directly obtained, and non-cross cut sets of the MCSs are simultaneously obtained; and compared with a conventional BDD method, the method provided by the invention is higher in calculation efficiency and more precise in result. The modularized BDD method has the advantages that the scale and number of the complex fault trees are reduced to lower the calculation cost, the memory consumption of the conventional BDD method is effectively reduced, and the calculation efficiency is simultaneously improved.

The invention discloses a ship alternative-current zone power distribution network system and a reliability analysis method thereof. The system is characterized in that an entire ship is divided into multiple zones, wherein the power supply of loads in one or more zones is guaranteed by one power generator unit, each power generator unit consists of a power generator, a power distribution panel, a circuit breaker and a load, an electric power bus passes through a watertight cabin from two sides of a cabin so as to join four power generators on the head and the end of the ship, and finally a circular power supply network is formed. The method comprises steps of drawing a corresponding reliability diagram according to a structure of the power distribution network; performing equivalence for local relatively-independent structures in serial connection or in parallel connection, and simplifying the reliability diagram; establishing different connection matrixes between one load point j and different power supplies; obtaining a minimal route according to the connection matrix so as to obtain a minimal cut set; eliminating the influence of a shared device on the calculation result by utilizing a session description protocol (SDP) method; and calculating a reliability parameter of the load point and a systematic reliability parameter.

The invention provides a nuclear power plant reactor protection system reliability analysis method. The method includes: determining a fault-tree model according to the structure and function of a nuclear power plant reactor protection system; calculating a minimal cut set causing top events; acquiring historical fault data of the nuclear power plant reactor protection system; calculating lifespan statistics of the nuclear power plant reactor protection system; establishing an information entropy model of lifespan distribution probability density function of the nuclear power plant reactor protection system and calculating the optimal lifespan distribution probability density function, failure probability, reliability and failure rate of the nuclear power plant reactor protection system. Integral lifespan distribution and dynamic failure rate of the system are predicated according to a small amount of reliability test data, the predication conforms to large-sample monte carlo simulation results, and the technical method is provided for predication of the system lifespan and evaluation of the dynamic failure rate of the nuclear power plant reactor protection system under the small failure probability condition.

The invention provides a code splitting method for converting traditional software into rich client software, which belongs to the field of software engineering. The method comprises the following steps of: firstly, carrying out data transmission volume plugging on an application procedure and testing, then generating a mould call graph, solving the smallest cut set of the graph, dividing the graph into two parts, and using the two parts respectively as a client code and a server code, thereby ensuring the minimum transmission volume of the applied network after splitting. When the traditional application is converted into rich client application, the invention can ensure that the transmission volume of the network after code splitting is minimum, thereby enhancing the property of the rich client application. The invention also allows program developers to directly set the functions at one end considered to be suitable, ensures the code to generate minimum transmission volume of the network after splitting, and can be suitable for various conditions for converting the traditional application into rich client application.

The invention discloses an importance degree calculation method for aerospace products. The influence of the uncertainty of risk basic events is considered; the severity of consequences caused by theevents is an important dimension of risk measurement, but such factor is not considered in a standard method; in view of this situation, the importance degree calculation method is adopted. Accordingto the method of the invention, the severity of the consequences caused by the risk basic events is considered; a minimum cut set order and the number of minimum cut sets containing risk basic events,such two factors are included in the importance degree analysis of the method of the present invention; the consistency of importance degree evaluation indexes is realized, a structural importance degree is taken as a parameter of the importance degree of the method of the present invention; order elimination adopts the ratios of current factor values to maximum values as factor values, so that the maximum value of each factor obtained after parameters are subjected to order-elimination is 1 assuredly. Compared with a normalization method, the order elimination method of the invention is notaffected by the number of the risk basic events. The importance degree calculation method is provided according to the characteristics of an FTA model and a PRA model, and therefore, the method of theinvention can be applied to the FTA and the PRA.

The invention provides a computer-based realization method for acquiring the minimal cut sets of a top event through the Boole function of a fault tree and carrying out non-intersection treatment on the minimal cut sets. The basic method of the non-intersection treatment comprises the steps of: dividing one event into the sum of subevents and complementary events thereof, and carrying out a plurality of such operation on intersecting events until non-intersection events are obtained through division. The computer-based realization method is realized by mapping the minimal cut sets into one set of n-dimensional vectors and defining an operation, corresponding to the intersection operation among the minimal cut sets, in the set. The computer-based realization method has the following characteristics that (1) as long as the minimal cut sets are coded, the coded minimal cut sets can be input into a computer and then subjected to the non-intersection treatment automatically by the computer, so that the automation degree is high, and no manual intervention is needed; and (2) the minimal cut set with the fewest bottom events is preferentially selected as the non-intersection minimal cut set, so that the number of the minimal cut sets is reduced after non-intersection treatment, and the top event failure probability is simpler to calculate.

The invention provides a method for solving the structural importance of an improved fault tree, which comprises the following steps: 1. First, find the minimum cut and path set of the fault tree, and then use the "four-principle comparison method" to find the fault tree based on The structural importance of the minimum cut set and the minimum path set are compared, and if the values ​​are the same, it means that the structural importance obtained by solving is correct, which is the final result. 2. If the sizes are inconsistent, it means that there is an error in the calculated structural importance. At this time, if the number of basic events in the minimum cut set and the minimum path set. If the number of basic events is small, use the "nine principles comparison method" to correct the structural importance error; if the number of basic events is large, use the "mathematical combination verification method" to correct the structural importance error.

The embodiment of the invention provides a reliability evaluation method for a hybrid alternating current and direct current power distribution network containing a flexible transformer substation. The method comprises the steps of obtaining a network topology of a power distribution network and a component reliability parameter value, and determining reliability parameters of distributed generation DG; according to the network topology of the power distribution network, constructing a power electronics transformer reliability model; by judging whether the DG can independently meet the load requirement or not, building a multi-power failure tree or a single-power failure tree corresponding to a load; according to the minimum cutset theory, utilizing the multi-power failure tree or the single-power failure tree, and calculating reliability indexes of loads in the power distribution network; according to the reliability indexes of the loads in the power distribution network, working outreliability indexes of the power distribution network. The purpose of power distribution reliability evaluation on the condition that non-commercialized operation power electronic transformer equipment is applied to the flexible transformer substation is achieved, and the technical support is provided for researchable and planning design of a flexible transformer substation project.

The invention relates to a nuclear power plant fault level calculation method based on probabilistic safety analysis and a computer. The method comprises the following steps: S1, establishing a minimum cut set database, exporting data files of the minimum cut set database in batches according to an accident sequence, and storing the data files in a table and database division manner; s2, performing quantification processing on the minimum cut set in the minimum cut set database; and S3, calculating risk information by using the quantified minimum cut set database. According to the algorithm for rapidly quantifying the risk level, the risk information of the nuclear power plant can be rapidly calculated, so that guidance is provided for various production activities of the nuclear power plant, better risk management and control are achieved, and the safety of a nuclear power unit is improved.

The invention provides a method for solving a fault tree top event probability based on combination of MCS and BDD, and aims to solve a Boolean expression of a fault tree by using a Boolean satisfiability problem solver aiming at the technical problems that memory explosion and inaccuracy are easily caused in the prior art. Based on a minimum cut set (Minimal Cut Set, MCS) of the fault tree, the degree of influence of a bottom event on the occurrence probability of a fault tree top event is measured according to the occurrence probability of the bottom event appearing in the minimum cut set, and the bottom event with the higher occurrence probability is selected to be preferentially added into the construction process of a binary decision graph, so as to reduce the structural complexity of the binary decision graph (BDD), the probability of memory explosion is reduced from the aspect of structural complexity, the solving process of the occurrence probability of the top event is optimized, and finally, fault tree quantitative analysis can be quickly and accurately carried out on the risk control object under a relatively low hardware operation condition.

The invention provides a rapid algorithm for the importance degree of a system fault tree bottom event structure. The rapid algorithm comprises the steps: constructing a fault tree bottom event modelof a system; obtaining a fault tree bottom event model, and obtaining a minimum cut set of fault tree bottom events and a structural expression F(X) of top events through a Boolean algebra simplification method, wherein the minimum cut set comprises a single event cut set and a multi-event cut set; performing calculating to obtain a bottom event structure importance degree of the single event cutset and a bottom event structure importance degree of the multi-event cut set; and performing ascending or descending sorting on all the obtained structure importance degrees according to the size. Structural importance priority ranking of all bottom events can be obtained through calculation results, and a basis is provided for strategy making for avoiding top events.

The present invention is an identification system comprising: an irrelevance trigger interpreting section for calculating a logical formula of irrelevance triggers for a component in a system from a cut set logical formula f of a system failure; and minimal cut set evaluating means for minimizing the logical formula of the irrelevance triggers, which has been calculated by said irrelevance trigger interpreting section, to calculate the irrelevance triggers for said component.

The invention relates to a railway conduction interference fault tree analysis method. The method comprises three steps: establishing a railway conduction interference fault tree, performing structured statistics on the fault tree, constructing a BDD form of the fault tree, and solving a minimum cut set of the fault tree. According to the method, the structure of the fault tree is split; statistics is carried out on the structuralization; and finally, a minimum cut set is solved; in the process, the structured statistics is not only used for counting the structured characteristics of the faulttree, but also used for directly relating the event sorting of the fault tree to the sorting of the events in the BDD structure converted by the fault tree, so the compactness of the structure is determined, and the path cost in the minimum cut set conversion process of the fault tree is saved.

The invention discloses a product design stage maintainability qualitative design method. The method comprises the following steps: establishing a maintainability design obstacle tree for a design target; performing qualitative analysis on the established maintainability design obstacle tree, and analyzing a minimum cut set and a minimum path set of the maintainability design obstacle tree to obtain a conflict vector of the design target; obtaining a corrected maintainability conflict matrix according to a TRIZ conflict matrix, determining a deterioration parameter and an improvement parameter of a maintainability design conflict matrix, and establishing a mapping relation between an invention principle set and a product design feature set. According to the method, a TRIZ original understanding vector is obtained by adopting a correction maintainability conflict matrix based on TRIZ, a relation matrix of a design conflict vector and an original understanding vector is obtained by combining the obtained conflict vector, and a conflict vector-original understanding vector relation equation of a corresponding conflict design system is established to help design decision making. The invention provides a method for solving the conflict problem between maintainability design requirements and other quality design characteristics.