84 results about "Reliability theory" patented technology

The invention discloses a composite material laminate non-probability reliability double-level optimization method. The method comprises: firstly, according to load-carrying characteristics of a composite material laminate, considering nondeterminacy effect of an intensity parameter of the composite material under condition of limited samples, based on a non-probability reliability theory, establishing a composite material laminate non-probability reliability evaluation model; in optimization of a first ply, using a simulated annealing method to optimize the composite material laminate, with thickness as a variable, and intensity reliability and rigid reliability as constraint; in optimization of a second ply, considering process constraint using stacking sequence as a variable, and optimizing with maximum intensity as target, through establishing a stacking scheme library which satisfies process requirements, using a genetic algorithm to optimize the stacking sequence of the laminate. The method ensures the composite material laminate has relatively high reliability and relatively low weight under nondeterminacy conditions, and meanwhile the method satisfies engineering actual technology level, and gives consideration to safety and economical efficiency.

The invention discloses a system for testing the service life of an electromagnetic relay coil and a service life evaluation method. By matched control of a voltage-stabilizing power supply, a timing switch and an alternation aging box, a plurality of groups of relays are respectively subjected to accelerated aging test and measured by a thermocouple temperature sensor, a resistance measurer and an insulating resistance measurer to obtain coil aging sensitivity parameters such as coil enameled wire average temperature, coil direct current resistance and coil insulating resistance, the average operating time of a plurality of groups of test is calculated by using a reliability theory, and the activation energy of a coil enameled wire is calculated by using a least square method, so parameters in a service life evaluation model are determined, and the average operating time (service life) of the relay coil can be evaluated by using the service life evaluation model with the determined parameters.

An anti-seismic control design method for a building structure selects the composition form of all parts according to the application situations of a ribbed structure system, determines the input intensities for frequent earthquake, basic fortification intensity earthquake and rare earthquake, and determines the structural computation model, namely determining the equivalent elastic plate model in the elastic stage, the rigid frame inclined compression bar model in the elasto-plastic stage and the beam-hinged frame model in the damage stage of the ribbed structure. The method considers the structural design control limit value as a random variable, utilizes a dynamical reliability theory to carry out structural design, can divide the earthquake function into a plurality of levels, can consider the variability of the structural parameters, leads the response and damage performance of the designed and built engineering structure to be within the expected range under various possible earthquake functions, ensures the safety of the life and the minimum economic loss, and carries out quantitative control design on the seismic response and damage.

The invention discloses a well wall instability risk quantitative evaluation method based on a reliability theory. The well wall instability risk quantitative evaluation method comprises the followingsteps: S1, according to basic data of a drilled stratum andS2, according to the input parameter uncertainty statistical table established in the step S1; S3, establishing a well wall collapse and well wall fracture instability limit state model; S4, according to the well wall instability limit state model in the step S3, respectively solving a well wall collapse pressure value and a well wall rupture pressure value under the limitation of a basic random variable; S5, giving a wellbore pressure mean value and a variable coefficient, and adopting Monte Carlo simulation to generate a wellbore pressure value under the given mean value and the variable coefficient; and S6, counting calculation results to obtain a quantitative evaluation result of the risk of borehole wall collapse and fractureinstability. The method has the beneficial effects that the well wall instability risk under the influence of parameter uncertainty can be quantitatively evaluated, and more accurate and effective decision basis can be provided for drilling technicians and constructors.

The invention relates to an aircraft navigation guidance and control ground simulation system performance evaluating method. Firstly, similar elements are chosen according to the system function principle, then numerical values and weight coefficients of all similar elements can be confirmed, and finally the similarity of a simulation system can be calculated out. The method can convert the performance evaluating problem into the practicable degree problem, can quantitatively analyze the heaven-earth consistency problem from aspects of dynamics, kinematics, measurement and navigation guidance and control and can objectively and quantitatively analyze the reliability of the ground simulation system based on the reliability theory. The evaluating method is clear in principle, simple in calculation, wider in application and capable of providing reference for performance analysis of other simulation systems.

The invention discloses a mechanism movement accuracy reliability analysis method based on a fuzzy out-crossing model. The mechanism movement accuracy reliability analysis method includes the steps of (1) building a generalized fuzzy random stress-strength interference model (please see the specifications for the model) according to task characteristics, (2) determining a subordinating degree function mu(x) of movement errors, (3) determining the reliability R(tau0) at the moment tau0, and calculating the complete up-crossing rate v+(tau) and the complete down-crossing rate v-(tau), and (4) calculating the fuzzy time-variation reliability R in the mechanism task executing process. By means of the mechanism movement accuracy reliability analysis method, influences of the errors and tolerances of mechanism movement on the mechanism accuracy reliability are considered, a time-variation reliability calculation method-PHI2 and a state fuzzy analysis method are combined, and the mechanism fuzzy time-variation reliability problem can be effectively solved; the aim that in a classical mechanism movement reliability theory, when the time-variation performance and the fuzzy performance are considered at the same time, the failure probability is calculated by properly changing the out-crossing model is achieved.

The invention discloses a spacecraft health evaluation method based on the profust reliability theory. The spacecraft health evaluation method includes seven steps that firstly, space division of the operation state of a spacecraft is performed; secondly, the state transition probability matrix computing method of the spacecraft is designed; thirdly, the stability probability computing method of the spacecraft is designed; fourthly, the profust reliability estimating method of the spacecraft is designed; fifthly, the determining method of the health level of the spacecraft is designed; sixthly, the computing method of the average vague fault time of the spacecraft is designed; seventhly, entering the design ending stage is performed. Calculation is performed with the profust reliability theory, the profust reliability, the health level and the average vague fault time of the spacecraft are obtained, and in-orbit health management of the spacecraft is supported. The spacecraft health evaluation method based on the profust reliability theory has good practical value and wide application prospects in the technical field of health management of the spacecraft.

The invention relates to a spare part demand predicting method based on state monitoring and reliability of an equipment part and belongs to the technical field of mechanical manufacturing. The method includes the following steps that firstly, according to a maintenance record list of equipment, the reliability theory is used for processing burn-out life data of parts in the maintenance record with the reliability theory, and the probability cumulative distribution function of the burn-out life of the parts is obtained; the probability cumulative distribution function of the burn-out life of the parts, the total working time of the equipment, the history record of the real spare part demand quantity, the year-to-year value record and the month-to-month value record of the spare part demand quantity, the experience predicting values of planners and the like are compared with errors, used for comparison predicting, of the real spare part demand quantity so as to obtain the predicting value of the demand quantity of equipment spare parts. According to the method, the prediction result of the method has the practical bases, the inactive stock of an enterprise can be effectively reduced, resource waste is reduced, cost is reduced and the method has good adaptability to different spare parts which are prone to damage.

The invention relates to a power station high-temperature pipe system maintenance method based on the non-probability reliability theory. The power station high-temperature pipe system maintenance method includes the steps of conducting finite element calculation on the strength of a power station high-temperature pipe system, determining key detection parts of the power station high-temperature pipe system, determining creep damage parameters with the non-probability reliability theory, building a creep damage probability model by determining the creep damage parameters, calculating structural failures according to the creep damage probability model, building a maintenance method model based on reliability analysis according to detected data, materials of the power station high-temperature pipe system and structure test results, and determining the optimum maintenance time of the high-temperature pipe system according to the maintenance method model and the actual engineering maintenance cost. The non-probability reliability maintenance method is achieved through the power station high-temperature pipe system, the structural probability reliability is efficiently and accurately determined, maintenance plans can be accurately determined, the maintenance method can solve similar problems of high-temperature pipes in other fields, and therefore the application range is wide.

The invention relates to a method for evaluating and assessing the state of relay protection equipment. The method includes building a relay protection equipment state assessment model according to classical reliability theories and historical maintenance data and combining the relay protection equipment state assessment model with related reference systems to give reasonable assumption for state information missing items of the protection equipment; evaluating and assessing running environments of relay protection devices and secondary circuits, fault-free time of operation boxes, insulation conditions of the circuits, anti-interference measures conditions, blocking conditions, device and circuit inspection conditions and the like according to the state assessment model and acquiring evaluating and assessing results; integrally evaluating the states of the relay protection devices and the states of the secondary circuits by the aid of the relay protection equipment state assessment model according to the evaluating and assessing results of the relay protection devices and the secondary circuits. The method has the advantages that the relay protection equipment maintenance management level and the equipment running reliability can be improved, the maintenance operation time and power grid maintenance shutdown time can be shortened, and the maintenance efficiency can be enhanced.

The invention discloses an optimization method of micro-electronic encapsulation thermal expansion coefficient reliability matching which introduces artificial intelligence theory, reliability theory and robust design theory into thermal design of micro-electronic encapsulation; micro-electronic encapsulation thermal expansion coefficient reliability matching and robust optimization based on the fusion of self-adaptive Gaussian neural network, three-level robust experimental design and non-linear finite element, use the thermal fatigue strain for encapsulating main thermal failure parts as the objective function in order to optimally match the thermal expansion coefficient of micro-electronic encapsulation device material under the effect of thermal cycle load, the optimally matched thermal expansion coefficient set is obtained in the design range, thereby reducing the maximum equivalent thermal fatigue strain inside the main thermal failure parts as much as possible. The method can both reduce the thermal mechanical failure rate of micro-electronic encapsulation under the effect of thermal cycle load, and ensure that the thermal expansion coefficient of material enables the encapsulation to maintain in high reliability under the disturbance of the thermal cycle load.

The invention relates to a method for valuing the construction period wind load of an ultra-large cooling tower. The method is characterized by comprising the following steps of: (1) establishing a structural design reference period, a time interval relation among different time intervals in the structural design reference period, a construction period, and a reliability relation among different time intervals of the construction period respectively by taking a reliability theory as a theoretical foundation with a time interval analysis method of structural reliability to form a time interval relation expression and a reliability relation expression; (2) resolving the relation expressions in the step (1) to obtain the proportion of a construction period wind load standard value to a design reference period wind load standard value; and (3) resolving a construction period wind load factor according to the proportion in the step (2). The valuing standard problem of the construction period design wind load of a tower is researched on the premise of the same reliability in the construction period of a cooling tower and the design reference period by taking the basic theory of a structural reliability design as a foundation, the determination of the design wind load in the construction period of the cooling tower is facilitated, and the method plays a role in deciding the stability and manufacturing cost of the cooling tower in the construction period.

The invention provides an intelligent connected vehicle corner danger warning method. The method comprises a step of establishing a vehicle aerodynamic model and a three-degree-of-freedom vehicle torque balance equation, further deriving a centrifugal force expression when a vehicle passes a corner, and then jointly calculating a threshold speed of vehicle rollover, a step of extracting state parameters related to the vehicle rollover, establishing a limit state equation of the vehicle rollover, optimizing the solution process of the limit state equation by a first-order quadratic matrix method in the reliability theory and obtaining a performance function, a step of establishing a vehicle rollover state prediction model through a checkpoint method, obtaining a vehicle rollover state indexand thus calculating the probability of vehicle driving safety, and a step of determining whether to carry out vehicle hazard warning or not according to the probability of vehicle driving safety. According to the method, the danger of a forward corner can be predicted in advance, the risk indicators of vehicle cornering risks caused by various vehicles, roads and environments are comprehensivelyanalyzed, quantitative prediction indicators are provided in real time, and the stability and safety of the vehicle in driving in a corner are ensured.

The invention discloses a gear pump health state evaluation method based on a profust reliability theory. The gear pump health state evaluation method comprises the following seven steps: I, designing selection of gear pump health state evaluation indexes; II, designing classification of gear pump health state grades; III, designing establishment of gear pump evaluation index subordinating degree functions; IV, designing calculation of gear pump evaluation index states and state transition probability; V, designing calculation of gear pump evaluation index profust reliability; VI, designing a profust reliability calculation method of the gear pump health state evaluation; and VII, designing gear pump health state grades and countermeasures. According to the invention, a theoretic basis for health state evaluation according to gear pump operation parameters is made up, the novel gear pump health state evaluation method is provided, and support is provided to health management of hydraulic pumps.

The invention belongs to the technical field of urban road network reliability evaluation and specifically relates to a function-based quantitative evaluation method of urban road network planning. Anurban road network is divided into several road segment units, the reliability theory is used, with pass function reliability as an evaluation index, a pass function reliability model of the road segment units is constructed, and according to the pass function reliability of the road segment units and the degrees of importance of the road segment units, the reliability of different urban road network layout patterns and the distribution rules of the degrees of importance of the road segment units in different urban road network layout patterns are quantitatively evaluated. A reference value is provided for the quantitative evaluation of urban road network planning schemes, the method is also can be applied to the quantitative evaluation of an existing urban road network, and a solution isprovided for the contradiction between the existing urban road network and an increasingly serious traffic problem in urban development.

The invention discloses a grey confidence interval-based reliability analysis method for a structure stress-intensity interference model set. For the problem that a conventional probability thought cannot provide effective estimation of a structure stress and intensity mean value due to finite sample information of structure stress and intensity parameters and difficult determination of statistic characteristics, the method comprises the steps of first defining grey distance measure of an inter-finite-sample topological relation and a distance relation, and performing grey generation of the grey distance measure to obtain an estimated value of the structure stress and intensity mean value; defining and solving a grey density index to obtain a confidence interval of the stress and intensity mean value under the condition of meeting the requirement of a certain grey confidence degree; and finally, introducing a structure reliability theory in a non-probability set theory framework to derive a two-dimensional reliability measure index for structure stress-intensity interference models, thereby realizing reasonable mapping of structure reliability analysis and confidence degree evaluation from samples, wherein the two-dimensional reliability measure index is of confidence degree significance.

The invention relates to a reservoir-induced earthquake probability calculation method and belongs to the field of analysis of reservoir-induced earthquakes. The reservoir-induced earthquake probability calculation method comprises the following steps: based on coulomb stress of a fault plane, establishing a functional function of fault earthquakes; taking a fault plane cohesive force, a fault plane friction coefficient, an actual water head of earthquake part pore water, coordinate plane stress, coordinate plane positive stress and a direction cosine of the fault plane in the functional function as random variables; calculating the probability of reservoir-induced earthquakes by applying a reliability theory. According to the reservoir-induced earthquake probability calculation method, factors, which influence the reservoir-induced earthquakes, are considered as the random variables and distribution types of the random variables are analyzed; the change of the stress of the fault plane is analyzed by adopting a coulomb stress theory which is widely adopted; based on the reliability theory, the probability of the reservoir-induced earthquakes is calculated and a novel concept is provided for analyzing the reservoir-induced earthquakes.

The invention discloses an uncertain factor-correlated four-high mill multidisciplinary reliability design optimization method. The method comprises the following steps: constructing a four-high mill multidisciplinary design optimization model; constructing a four-high mill uncertain factor-correlated quantification model; constructing a four-high mill multidisciplinary design optimization model under an uncertain factor-correlated condition; converting the related uncertain factors into independent uncertain factors and calculating the reliability; and constructing a four-high mill multidisciplinary reliability design optimization model under uncertain factor-correlated condition so as to realize the four-high mill multidisciplinary reliability design optimization. According to the method, the hyper-ellipsoid theory, the reliability theory and the multidisciplinary design optimization theory are combined, so that the incorrect design result caused by neglecting the correlation among the uncertain factors in the traditional design method is solved, and the requirement for high reliability of complicated mechanical products is satisfied.

The method discloses a method for non-probability reliability optimization of a composite laminated plate. The method comprises the steps that firstly, according to force bearing characteristics of the composite laminated plate and with consideration of uncertainty effects of material fiber strength under limited samples, a non-probability reliability assessment model of the composite laminated plate is established based on non-probability reliability theories; and a gradient optimization method is further adopted, a light weight is taken as a goal, reliability is taken as a constraint, a paving layer thickness is taken as an optimization variable, and a composite paving layer scheme which can satisfy certain reliability requirements can be obtained through iterations. The method has the advantages that the composite laminated plate can have the high reliability and the light weight under uncertainty conditions; and safety and economic efficiency are also ensured.

The method of the invention analyzes a fuzzy shortest path from a new angle, introduces the reliability theory into the problem of the fuzzy shortest path, performs the characteristics that creditability measure has self-duality, truly represents the establishment of a fuzzy event and overcomes the deficiency of the possibility theory. Meanwhile, the invention overcomes the problem that the shortest path is hard to choose because of large traffic network scale and numerous non-dominant paths, puts forward an alpha-shortest path for the first time and designs a searching method of the shortest path on the basis of the fuzzy simulated genetic algorithm. In the method, the weight number of the arc in the network can be arbitrary fuzzy number, avoids the boundedness of the special fuzzy number and can satisfy the requirements of fuzzy shortest path searching generality.

The invention discloses a BP neural-network algorithm-based status evaluation method of relay protection equipment. The method includes: constructing neural units of a status evaluation model on the basis of classical reliability theory and historical maintenance data, carrying our training and learning on the basis of a large number of samples, and forming a status evaluation model algorithm through a BP algorithm; adopting the status evaluation model to estimate situations of an equipment running environment of the relay protection equipment and the like to obtain estimation results on the relay protection device; adopting the status evaluation model to estimate device circuit inspection situations of a running environment of a secondary circuit and the like to obtain estimation resultson the secondary circuit; and obtaining an overhaul range according to the estimation results of the relay protection device and the secondary circuit. By applying the embodiment provided by the invention, quantitative analysis, monitoring and early warning are carried out on the relay protection equipment through the perfect estimation and evaluation method of the relay protection device and thesecondary circuit and combination of the data model of the relay protection equipment.

The invention discloses a method of optimizing a gantry bent structure on the basis of non-probabilistic reliability theory. The method includes the steps of determining bending resistance values of a column and a beam; determining allowable moments of the column and the beam; comparing failure probability, acquired on the basis of an interval convex set model, to failure probability, acquired on the basis of an ellipsoidal convex set model so as to optimize the gantry bent structure. Compared with the traditional methods, the method has the advantages that fewer constraint design gantry bents are used, the efficiency of optimal design of the gantry bents is improved, and application of the bents to engineering is facilitated.

The invention discloses a separation reliability simulation platform for a multistage carrying spacecraft. The multistage carrying spacecraft comprises an upper stage and a lower stage, and the simulation platform comprises a test parameter setting subsystem, a separation dynamics simulation subsystem and a reliability analyzing subsystem. The test parameter setting subsystem serves as a bottom layer of the simulation platform, configures random test parameters by reading a standard parameter setting file, and utilizes an interface to adjust and modify part of parameters. The separation dynamics simulation subsystem conducts separation dynamics simulation on the multistage carrying spacecraft according to three stages. The reliability analyzing subsystem analyzes the separation reliabilityand significance level of the whole separation stage according to data obtained in multiple simulation processes of the separation dynamics simulation subsystem. According to the separation reliability simulation platform for the multistage carrying spacecraft, a separation system is combined with a reliability theory, and integrated analysis from configuration, simulation to reliability verification is achieved.

The invention provides a mobile node vulnerability discrimination method by using reliability vector projection decomposition. The method comprises the following steps: (1) determining reliability vector space according to multi-source vulnerability information; (2) calculating a reliability value of each vulnerability scan tool scan result; (3) calculating each reliability vector and a cosine value of each reference axis included angle in the reliability vector space; (4) calculating a projection decomposition value of each reference axis in each reliability vector to the reliability vector space; (5) accumulating obtained projection values on reference axes to obtain a sum, and carrying out normalization; (6) determining reliability of each vulnerability, and according to a reliability size, determining vulnerability existed in the mobile node. Compared with the prior art, the method in the invention has the following substantial advantages: based on a reliability theory, influence of an uncertainty factor in a vulnerability detection process is effectively avoided; by taking a plurality of detection tools as information source, accuracy of vulnerability discrimination is raised; by employing a calculation method of reliability vector projection decomposition, each decomposed vector is converted into a monoatomic set, and calculation complexity is decreased.

The invention provides a high-reliability fuel cell pilestack package designing method and belongs to the technical field of fuel cell pilestack system packaging technologies. A mechanic theory and a reliability theory are utilized to simplify a cell pilestack to sequentially determine a change law of reliability of assemblies in the cell pilestack along with contact stress, further the optimal contact stress of all the assemblies can be determined, and the sizes and package force of the cell pilestack assemblies are designed to achieve the purpose of improving cell pilestack reliability. The high-reliability fuel cell pilestack package designing method disclosed by the invention is convenient, quick, flexible and changeable, can greatly reduce calculation consumption under the situation that package accuracy is guaranteed and shortens a cell pilestack package designing period.

The invention discloses a high-reliability spray liquid transporting and measurement and control device used in marine diesel engine waste gas desulfurization and belongs to the fields of air pollution control and ship waste gas emission control. A desulfurization system is composed of a washing kettle, a neutralizing treatment device, a water sump, an alkaline solution pot, a solid-liquid separator, a saturated liquid pot, a solid material discharge cabin, transporting and measurement and control devices for treatment mixed liquids and the like, and the like other units. Marine diesel engine waste gas enters the washing kettle and is fully mixed and contacted with a sprayed desulfurizing alkaline water solution, and then is subjected to neutralization treatment to dissolve and absorb the sulfur oxides in the waste gas to form sulfates, wherein other particles in the waste gas are also adhered to and mixed with the water solution. The treated waste gas finally is subjected to separation, treatment and recycling. On the basis of reliability theories and methods, series-parallel connection combined design of the parts of the spray liquid transporting and measurement and control device in the marine diesel engine waste gas desulfurization system is carried out. The device is reduced in fault probability, greatly increases the reliability of the waste gas desulfurization system and can satisfy the demand of marine diesel engine waste gas desulfurization.

The invention discloses a thread division method based on process importance. The method comprises the following steps of: generating a process initial division scheme and calculating a process importance degree; combining the initial division scheme of the process and the importance degree of the process to generate a process optimal partitioning scheme. According to the invention, the initial division scheme of the process is generated based on the thread division method based on machine learning; by adopting the interdisciplinary research method, an importance theory in a reliability theoryis introduced into the research of a thread division method, the importance is calculated according to the characteristics of the process; the situation that an explicit division method (manual intervention division flag bit) is added to the implicit division (initial division scheme generation process) is explored, and evaluating is carried out by utilizing a performance evaluation model, thereby finding out an optimal division scheme of the process, and verifying that the explicit parallelization effect is always superior to the implicit parallelization theory.

The invention discloses an accelerated test and prediction method for the service life of a laser optical component so that a problem that the service life of the large-caliber optical component underrandom flux illumination can not be obtained in the prior art can be solved. The method comprises: fitting is carried out by using a transmitting number or time as an independent variable and a corresponding service life probability as a dependent variable to obtain a service life probability function of a large-caliber optical component under a specific laser parameter; and the irradiation fluxof illuminating laser with a set parameter is changed to obtain a service life probability curve of the large-caliber optical component under different irradiation fluxes and data fitting is carried out on the function to obtain a service life flux function under the specific service life probability. According to the invention, accelerated testing of the service life of the laser optical component is realized; the test time is shortened. With the test result, the service life of the large-caliber optical component under the specific flux can be obtained; and on the basis of the classical reliability theory, the reliability analysis and prediction are carried out on the laser large-caliber optical component in the laser system. The accelerated test and prediction method is suitable for theservice life testing field of the large-caliber optical component.

The invention relates to a UHF RFID intelligent supervision shelf system architecture and method, which is characterized in that the system architecture and method take the placement and constructionof a common shelf as a design principle, and for the first time, the UHF RFID technology is utilized to carry out shelf supervision and management through a standardized shelf adjustment mode. A set of intelligent shelf monitoring method with high reliability and high accuracy is innovatively created to achieve a set of adjustment and deployment strategy based on the system. In the architecture ofthe system, the shelves are labeled with fixed point locations, a single reader is deployed in front of the smart shelves, and the deployment distance is controlled so that the entire reader covers the entire shelf. The system realizes the one-to-one correspondence between the theoretical value and the actual value by using the phase matching, and then realizes the deployment and reliability calculation of each shelf level by using the reliability theory, and divides the layers by using the RSSI, so as to realize the reliability deployment and real-time monitoring service of the intelligent shelf.

The invention provides a pollution-flashover-caused trip probability calculation method of overhead lines in a sand and dust environment. The method comprises: based on sandstorm weather information, building a deposit model of sand and dust particles on an overhead line insulator surface and calculates equivalent salt deposit density and equivalent dust deposit density on the insulator surface; by taking into account the feature that a dust-to-salt ratio in a sandstorm-prone area is high, building a transmission line pollution-flashover-caused trip probability model which comprehensively considers salt density and dust density on the insulator surface; combining relative studies on insulator probability statistics and line reliability theories, and assessing a overhead line pollution-flashover-caused trip risk in the sand and dust environment; and then, on the basis of relative humidity influence on insulator flashover leakage current, building a line pollution-flashover-caused trip model in wet weather after sandstorms, and assessing influence of relative humidity changes on the overhead line pollution-flashover-caused trip probability. According to the invention, possible overhead line trip faults are prevented, and a safe and stable operational level of a grid in sand and dust environment is improved.