111results about How to "The evaluation result is reasonable" patented technology

The invention discloses a method for evaluating the foundation stability of a coal mining subsidence area. The method comprises the following steps of (1) calculating the height of a caving fracture zone: according to different geological and mining conditions, measuring related parameters and selecting a calculation formula or an empirical formula for the height of the caving fracture zone; (2) calculating the load impact depth of the coal mining subsidence area: according to the geological stratum conditions of a goaf, analyzing the gravity stress and additional ground stress of a foundation and determining a calculation method for the building load impact depth of the coal mining subsidence area; and (3) evaluating the foundation stability of the coal mining subsidence area: according to a mutual relation among the mining depth H<mining> of a coal seam, the height H<fracture> of the caving fracture zone in the coal mining subsidence area and the building load impact depth H<impact>, evaluating the foundation stability of the coal mining subsidence area. The method is suitable for foundation stability evaluation of different mining methods and mining processes under different geological and mining conditions, and is wider in application range and good in evaluation effect.

A credibility evaluation method of software units of a complex software system includes the following steps: A building a credibility index system; B determining a credibility evaluation comment set; C acquiring an objective weight through factor analysis by aid of SPSS (Statistic Package for Social Science), acquiring a subjective weight with an analytic hierarchy process and determining the final factor weights with a dynamic assignment method; D conducting first-level fuzzy evaluation on credibility of the software units; E correcting the evaluation result through multiple fuzzy composition operators; F iterating the above calculation process to achieve multi-level fuzzy comprehensive evaluation on the credibility of the software units. The credibility evaluation method classifies evaluation indexes, so that an evaluation result is more reliable; acquired index weight values better accord with the practical condition of the software units, so an objective and subjective weight structure can be adjusted dynamically according to different software units; the evaluation result is corrected through the multiple fuzzy composition operators so that the evaluation result is more scientific, accurate and reasonable.

The invention particularly relates to a power grid node comprehensive vulnerability index calculation method based on a network analytic hierarchy process. The method aims to solve the problem that node structure vulnerability and node state vulnerability are not independent, the node structure vulnerability and node state vulnerability are connected with each other, but a common analytic hierarchy process theoretically requires that the node structure vulnerability and node state vulnerability s are independent of each other, in practical application, the evaluation result of the vulnerability is unreasonable; therefore, the method is based on a network analytic hierarchy process, in the aspect of expert decision making, the mutual relation between the node structure vulnerability and thenode state vulnerability assessment result is considered; the obtained weight is more accurate; and on the other hand, an entropy weight method is utilized to reflect an objective weight value to correct the power grid node structure vulnerability and node state vulnerability weight obtained by the network analytic hierarchy process, so that a comprehensive vulnerability evaluation result of eachnode of the power grid is obtained through calculation, and sorting is carried out to judge weak links existing in the power grid. The method can meet the requirement of power grid node comprehensivevulnerability assessment under the large power grid interconnection background.

The invention relates to the technical field of geological disaster evaluation, in particular to a geological disaster susceptibility evaluation method and device, wherein the method comprises the following steps of selecting an evaluation factor of a study region, wherein each evaluation factor has various types; obtaining the weight among the evaluation factors; calculating different kinds of information quantity values of each kind of evaluation factor according to the existing disaster region factor obtained in advance; calculating the integral information quantity value of the study region according to different kinds of information quantity value of each kind of evaluation factor and the weight among the evaluation factors; determining the geological disaster susceptibility evaluation result of the study region according to the integral information quantity value. By using the method, the geological disaster susceptibility evaluation result errors are reduced.

An electric power communication network survivability evaluating method comprises the following steps: a, parts of an electric power communication network are abstracted as nodes, and physical links are abstracted as edges; b, network efficiency in an original state is calculated; c, each node and each edge are deleted in order, and network efficiency of a newly generated graph is calculated; d, fault influence degrees of each node and each edge are calculated; e, a whole-network survivability degree is calculated; and f, evaluation is carried out on the survivability of the electric power communication network through utilizing the whole-network survivability degree. According to the electric power communication network survivability evaluating method of the invention, the importance degree of each part in the electric power communication system for network performance is taken into consideration, and at the same time, effects of the links in the network are taken into consideration, so that a whole destroy process of the electric power communication system can be reflected. The method eliminates one-sidedness of existing evaluating methods. According to the method of the invention, the evaluated results are more objective and reasonable. At the beginning of an electric power communication network topological structure design process, the method is utilized to carry out quantitative analysis on the survivability of the network, and accordingly a design scheme of the network can be optimized and the survivability degree of the network is raised.

The invention relates to a local solar energy resource abundance evaluating system for design of a photovoltaic power station, which can be widely applied to scientific research and engineering application in the fields related to solar energy. In the system, a data acquisition module is used for acquiring various indexes of four meteorological parameters from a meteorological observation system; an integrated operation module is used for operating and analyzing the acquired meteorological data by a representative meteorological year and month method; an evaluation and quantization value acquisition module is used for stacking annual daily total solar radiation data generated in the integrated operation module to acquire an evaluation and quantization value; and a solar energy resource evaluation module is used for comparing the quantization value with an evaluation system to acquire an abundance evaluation result of the solar energy resources. The system can be widely applicable to various areas and climate conditions, the generated annual daily solar radiation data have representativeness, the evaluation result is objective and reasonable, and the system can meet the requirements on design engineering application of the photovoltaic power station.

The invention is a general river water quality estimate method with index mark and relates to a new river water general quality estimate method. The invention estimate the general water quality with the help of general water quality index mark WQI which consists of the integer numbers and the numbers after arithmetic point totally three to four effective digits which is WQI=X1X2X3X4. X1 stands for the general water quality variety and X2 the location the general water quality is in in the X1 interval and X3 the compare result of the general water quality variety with water environment function area variety namely the pollution stage of the water section and X4 for the numbers of the water index marks which do not meet the water environment function section objective. The general water quality mark consists of two parts in which X1X2 is the general water quality index mark and X3X4 the marking. The invention is able to fully describle the general water quality information so to estimate the water in quality and quantity.

The invention discloses a comprehensive evaluation method for the operating state health degree of a direct-current system for a station. The method includes the following steps that: A, an evaluationindex system taking factors such as equipment health, operation defects, service life, voltage and current operating status of the direct-current system into consideration is built; B, index values are obtained through statistical calculation, and the index values are standardized and normalized; subjective and objective weights are calculated on the basis of an improved analytic hierarchy process and standard deviation and average difference algorithms; and D, and two quantitative evaluation results of the operating state health degree of the direct-current system to be evaluated are obtained through a linear weighting method. According to the comprehensive evaluation method, an evaluation process takes into account not only the subjectivity and objectivity of evaluation, but also embodies the degree of the importance of different evaluation indexes on the evaluation results; the evaluation results tend to be more reasonable and can better distinguish the change process of the healthdegree of the operating state of the system in a more microcosmic and detailed manner; and quantitative basis can be provided for optimal decision-making in the maintenance and repair programs of thedirect-current system.

The invention discloses a solar power generation capacity prediction method for a photovoltaic power station. The method includes the steps of firstly, calculating the annual average peak sunshine hours of recent years of the region where the photovoltaic power station is located and the installed capacity of the photovoltaic power station; secondly, calculating the solar power generation capacity Wn of the nth year of the photovoltaic power station and the total solar power generation capacity Wtotal of set years of the photovoltaic power station according to the annual average peak sunshine hours, the installed capacity and photovoltaic module attenuation rates. The method has the advantages that the method is applicable to various regions and meteorological conditions, the generated daily average irradiance of each month, annular average irradiance, installed capacity, annual solar power generation capacity in N years and total solar power generation capacity are representative, solar irradiation data accuracy of regions away from a local solar irradiation observation station or regions without a solar irradiation observation station is increased, and prediction and evaluation results are objective and reasonable.

The invention provides a rainfall information collecting and early-warning system for a high speed railway. The rainfall information collecting and early-warning system comprises a rainfall information collecting device, a current signal / numerical signal conversion device, a device for dynamically generating rainfall disaster risk reference threshold values, an early-warning program starting deciding deice, a locating device, a train control device for controlling the speed of a train, a storage device and a control device; a control module serves as the kernel of the whole system, on one hand, the control module controls operation of all the mentioned devices, and on the other hand, the control module is used for being connected with an external computer device and other external equipment to achieve communication and control. According to the system, the reference threshold values for evaluating rainfall disaster risks are dynamically generated, and combined with historical disaster occur conditions which are continuously updated after the newest early-warning occurs, risk beforehand evaluation of a certain region is considered more completely and scientifically through comparison with historical data. The invention further provides a rainfall information collecting and early-warning method for the high speed railway.

The invention discloses a network safety situation evaluation method and device, and the method comprises the steps that a network information obtaining module detects the change of IP address statesof network traffic flow of new and old users in a network through an IP address database so as to obtain a risk value of the network, and calculates a risk index of each node of the network by using the risk value; a fusion situation information module integrates the risk indexes of all nodes of the network, generates an integration risk index of the network, and uses the fuzzy C-mean clustering algorithm to divide the integration risk index into five security levels; a network situation evaluation module generates the safety situation of the network according to integration risk index of thenetwork through combining with different security levels. The method provided by the invention not only realizes the safety security situation evaluation of a DDoS attack in a big data environment, but also effectively improves the flexibility of the network safety situation evaluation method and the accuracy of the evaluation result.

The invention discloses a power utilization quality comprehensive evaluation method for a power demand side. The power utilization quality comprehensive evaluation method comprises a first step of finishing data collection and transmission of power distribution network monitoring points of the power demand side; a second step of establishing power quality grades for power quality indexes, and performing unitization processing on the established grades according to benefit type indexes and cost type indexes; a third step of utilizing a Bayes method to correct the indexes on the basis of obtaining of subjective weights, and obtaining weight optimization values of various indexes through an optimization algorithm with constraints; a fourth step of performing grading evaluation on various power indexes of the monitoring points by means of an attribute recognition model; and a fifth step of obtaining comprehensive evaluation grades of power quality by calculation according to the weight optimization values, and finishing quantitative evaluation on the power quality. Reasonable calculation of the weights of various indexes of power is achieved through the power utilization quality comprehensive evaluation method, reasonability and reliability of power comprehensive evaluation results are improved, and reliable information can be provided for power grid safety.

The invention discloses a blowout accident risk analysis method, and particularly relates to the field of energy exploitation, and the method comprises the following specific analysis steps: S1, analyzing main cause of well kick-blowout accidents and influence factors of the well kick- blowout accidents; s2, establishing well kick- blowout accident tree; s3, converting the accident tree into a Bayesian network model by using GeNIe; s4, performing quantitative analysis on the Bayesian network model; s5, finding out a key cause factor; and S6, proposing a measure for controlling the key cause factor. According to the invention, accident causes are analyzed; the analyzed cause of the blowout accident is compiled; a reasonable blowout out-of-control accident tree and a blowout out-of-control Bayesian network model are obtained, the blowout out-of-control Bayesian network model is subjected to quantitative analysis and three importance analysis, key cause factors causing blowout accidents are found out, and a key role is played in controlling the blowout accidents.

The invention discloses an optimization system for a virtual and actual interactive traffic evacuation control scheme. The system comprises a database, a model base, an actual traffic system, a virtual traffic system, a decision supporting platform and an evacuation scheme base, wherein the virtual traffic system synchronously interacts with the actual traffic system, so that parallel description of a traffic evacuation environment is realized; and the decision supporting platform comprises an evacuation scene generation module, a weather scene generation module, an evacuation scheme generation module and an evacuation result evaluation module and is used for finishing a traffic evacuation experiment function during a large activity, generating a traffic evacuation scene under normal and abnormal weather conditions and evaluating the an evacuation scheme effect. The optimization system supplies decision support to a traffic evacuation process through interaction between the virtual system and the actual system.

Disclosed is an assessment method of the contribution of the shellfish biology deposition to the offshore environment sediment organic carbon. The assessment method comprises adopting an indoor simulation experiment, collecting feces of typical shellfishes in different seasons, determining the organic carbon, the total nitrogen and the carbon isotope abundance in the shellfish biology deposition, performing analysis on a large number of data samples and building a shellfish biology sediment organic carbon traceability technology system; combining with the burial characteristics of the offshore culture zone sediment organic carbon and determining a potential source of the culture zone sediment organic carbon through a carbon isotope and carbon nitrogen ratio diagram; estimating the contribution of the shellfish biology deposition to the offshore carbon cycle based on a multiple mixed model. According to the assessment method of the contribution of the shellfish biology deposition to the offshore environment sediment organic carbon, the transition and transformation process of different sources such as the shellfish feces in the marine environment is fully considered and accordingly the final assessment result is close to reality and reasonable.

The invention relates to a wind electricity power short-term combined prediction method considering run detection method reconstruction. The method includes the following steps that: a plurality of groups of output time sequence sample data of a wind farm are decomposed through adopting empirical mode decomposition, so that a plurality of intrinsic mode functions (IMF) and trend items Res can be obtained; fluctuation degree classification is performed on the intrinsic mode functions obtained through decomposition and remaining components according to a run discriminating method, and EMD decomposition items with similar fluctuation frequencies are reconstructed; and data normalization processing is performed on the reconstructed components, and processed components are adopted as training and testing data of a neural network, and an EMD-Elman prediction model direct multi-step method is established to perform 72h day-ahead power prediction. According to the method of the invention, the accurate EMD-Elman neural network short-time multi-step combined prediction model is established, and therefore, the number of models built for predictive components can be decreased, and prediction accuracy and prediction speed can be improved.

The invention discloses a grey fuzzy comprehensive evaluation-based trust quantization method, which belongs to the computer security field and is used for solving the trust quantization problem when an entity accesses resources in a distributed environment. Aiming at dynamics and fuzziness of trust, the invention provides the grey fuzzy comprehensive evaluation-based trust quantization method. When the behavior of a main body is changed, the trust quantization value of the main body is changed therewith. An object node accessed by the main body is randomly selected, the object node and the current accessed object are taken as 'experts' for evaluating the trust of the main body to comprehensively evaluate the behavior of the main body, and the specific trust value is calculated according to a trust interval corresponding to the evaluation result. The method can well evaluate the trust degree of the main body and reasonably quantize the trust degree. The randomly selected evaluation experts can avoid united cheat among the nodes. The method can be flexibly applied to various distributed environments, and has good practicability.

The invention discloses a construction engineering project evaluation system comprising a server terminal, a project generation terminal, an evaluation system, a management terminal and a database system. The project generation terminal is used for generating subprojects in the engineering project and establishing a basic evaluation model and transmitting the basic evaluation model to the server terminal. The evaluation system includes multiple evaluation terminals based on the expert consultation method and is used for scoring each primary index of the basic evaluation model of the subprojects. The subprojects are evaluated and index description is enabled to be detailed so that accurate elaboration for each angle of the project implementation effect can be realized and the degree of the implementation quality of the subprojects can be better reflected; and expert consultation and scoring are performed so that the interference of subjective factors can be reduced, the project effect can be displayed in a more targeted way by using the weight evaluation system and thus the evaluation result is enabled to be more reasonable.

The invention discloses a node voltage sag severity multi-index evaluation method, which selects a plurality of evaluation indexes to establish an evaluation index set, overcomes the defect that onlyone aspect of the power supply side or the power consumption side is considered in the traditional evaluation method, and combines the two together to make the evaluation result more comprehensive. Atthe same time, the comprehensive weighting method based on AHP and CRITIC method is used to give new weight to the indexes, which not only fully considers the deep internal correlation among the evaluation indexes, but also reflects their relative importance, so that the evaluation results are more reasonable. The simulation results show that the method can reflect the actual situation of distribution network more truly, can accurately and effectively identify the weak nodes and vulnerable areas in the network, and lay the foundation for the treatment of voltage sag.

A non-linear optimization decision-making method of planning schemes for oilfield development comprises the following steps that A a planning scheme set to be optimized and a scheme evaluation index set are determined; B an attribute decision-making matrix is built according to index attribute data provided by the schemes; C standardization is performed through different methods according to different index attribute types so that the decision-making matrix can be converted into a standardized decision-making matrix; D the weight of each index attribute is calculated through a combination weighting method, subjective and objective combination is achieved, and the just and ideal weight of each index attribute is obtained; E a weighted standardized matrix is built by means of the standardized matrix obtained in the step C and the weights obtained in the step D; F the schemes are sequenced according to strengths and weaknesses to obtain the optimal scheme by means of an evaluation decision-making model. The method solves the problem that the weights of the index attributes are too objective or subjective, relieves the degree of influence on the weights from the maximum deviation of the index attributes and makes an evaluation result be more scientific, accurate, just and reasonable.

The invention discloses a power distribution network power quality monitoring and comprehensive evaluation system and method. The method comprises the following steps: S1, monitoring power quality indexes through a power quality monitoring terminal, and summarizing the power quality indexes by a monitoring center master station; s2, performing dimensionless processing on the power quality indexesthrough range change, and obtaining objective weights of the power quality by applying a CRITIC method; s3, obtaining a subjective weight by applying an improved expert scoring method; s4, performingsubjective and objective combination to obtain a combined weight; and S5, grading the electric energy quality standard data, and obtaining an evaluation result and a corresponding electric energy quality grade through a weighted TOPSIS method. The electric energy quality indexes are monitored based on the electric energy quality monitoring terminal, and combined evaluation analysis is carried out,so the limitation of a single weighting method on electric energy quality evaluation is avoided.

The invention discloses an algorithm for evaluating the comprehensive efficiency of an objective method of image quality. The algorithm has the following core: firstly, designing the performance evaluation index of a necessary objective evaluation algorithm of the image quality from different measurement angles so as to comprehensively evaluate the performance advantages and disadvantages of various algorithms; secondly, unifying the evaluation criterion of each index to cause the evaluation result data of each index to exhibit consistency; and finally, designing a simple and effective fusion algorithm. The algorithm can fuse different evaluation indexes and different test image databases, final result data obtained through the algorithm can reflect the comprehensive efficiency of various objective evaluation algorithms of the image quality so as to provide a basis for the screening and the application of various algorithms.

The invention relates to a bias tunnel construction safety evaluation method based on variable weight fuzzy comprehensive evaluation. The method comprises the steps: 1, determining a bias tunnel construction safety evaluation index system: a first layer is a target layer, a second layer is a criterion layer, and a third layer is an index layer; wherein the criterion layer selects four evaluation indexes which comprises bias degree, surrounding rock characteristics, tunnel characteristics and hydrological characteristics; determining grading standards of the evaluation indexes; 2, obtaining anindex initial weight by adopting an analytic hierarchy process, and carrying out variable weight adjustment on the index initial weight according to the dynamic index data; 3, performing grade evaluation on the safety evaluation index system after variable weight adjustment based on fuzzy comprehensive evaluation; and 4, comprehensively judging the construction safety level of the bias tunnel according to the evaluation level. According to the method, a fuzzy variable weight analytic hierarchy process is applied to bias tunnel construction safety evaluation, and bias tunnel construction safetyevaluation is carried out in a more objective and effective manner, so that a safer construction method is obtained.

The invention discloses a fuzzy comprehensive assessment method for a railway snow disaster risk. The method comprises the following steps: establishing a factor set for measuring the railway snow disaster risk; setting a railway snow disaster risk assessment level; collecting expert opinions, performing secondary risk evaluation matrix assessment, and establishing a railway snow disaster fuzzy expert evaluation matrix; determining each risk indicator weight based on an improved group analytic hierarchy process; determining a secondary fuzzy assessment vector; determining the membership vector of a railway disaster risk factor set specific to a comment set; and determining a railway snow disaster risk assessment level by comprehensively adopting a confidence criterion and a level characteristic value formula. According to the method, the improved group analytic hierarchy process is combined with a fuzzy comprehensive evaluation method, so that accurate assessment of the railway snow disaster risk is realized, and the influence of a snow disaster on railway transportation and the society is lowered. The method has important theoretical significance to scientific and accurate formulation of disaster prevention and disaster preparedness measures and prevention of possible railway sudden accidents.

The invention discloses an electromechanical product processing technology evaluation system and method, and the system comprises a manufacturing technology storage module, an evaluation index construction module, a green technology evaluation module connected with the evaluation index construction module, and a combined technology evaluation module connected with the manufacturing technology storage module and the evaluation index construction module. The evaluation indexes comprise a plurality of first-level indexes, each first-level index comprises a plurality of second-level indexes, and the first-level indexes comprise processing quality, processing time, processing cost, resource consumption and environmental influence; the green process evaluation module comprises a dimension conversion module, a first-level index weight calculation module, a second-level index weight calculation module and an ideal scheme determination module which are sequentially connected; and the combined process evaluation module comprises an original method set evaluation module, a compatibility method set screening module and a comprehensive evaluation module which are sequentially connected.

The invention discloses a source network load storage coordination level evaluation method based on a risk thought. The source network load storage coordination level evaluation method is characterized in that a source-grid-load-storage coordination level evaluation model is provided under the background that the source-grid-load-storage coordination optimization mode becomes the development trendof the power system; the source-grid-load-storage coordination level evaluation model firstly analyzes internal and external uncertain factors affecting the coordination ability of the system based on the idea of risk identification, and then establishes an evaluation index system considering multi-agent interaction and layering; and secondly, the source-grid-load-storage coordination level evaluation model proposes a quantitative calculation method of quantitative indexes and a processing mode of qualitative indexes, establishes a source-network-load-storage coordination level evaluation model, and determines the weight of each level of indexes by using an analytic hierarchy process and a Delphi method in combination with an empowerment method. According to the constructed evaluation model, the source-grid-load-storage coordination level of the power system is scientifically and systematically evaluated for planning schemes of three areas of a certain province, and a decision reference is provided for planning and operation scheme optimization of the power department, and the intrinsic safety level of the system can be improved.

A method for evaluating the economic operation of active distribution networks based on hypersphere support vector machines, including the following steps: define six indicators under the background of large-scale distributed energy access to active distribution networks; compare the defined six indicators with the actual Combining existing indicators to build an evaluation index system for the economic operation of the active distribution network, and improving some existing indicators; using the system gap index and system coordination index to reduce the dimensionality of the index system; establishing an active distribution network based on hyperspherical support vector machines The hypersphere model of each level; the overlapping area is improved, and the evaluation level is judged by the judgment function. The present invention fully considers the impact of large-scale distributed energy access to the active distribution network, corrects some existing indicators, uses dimension reduction processing to solve the problem of redundancy in high-dimensional indicators, and combines the evaluation level with the hypersphere support vector Combined with the computer, the evaluation grade results can be obtained quickly and accurately, which is very reasonable.

The invention discloses a reliability evaluation method for a top beam of a hydraulic bracket. The method comprises the following steps: S1, determining a hyper-ellipsoidal model which describes uncertain parameters for uncertain parameters in a top beam design of the hydraulic bracket; S2, determining a main failure mode of the top beam of the hydraulic bracket and determining a corresponding functional function; S3, carrying out reliability analysis on the functional function to determine a reliability index; and S4, carrying out reliability evaluation on the top beam of the hydraulic bracket according to the reliability index. The method disclosed by the invention is simple in step and convenient to operate, can be used for carrying out reliability evaluation on the hydraulic bracket by effectively applying sample information, so that the reliability evaluation precision is improved, the evaluation result is effective and reasonable, and the method is strong in practicality, good in using effect and convenient to popularize and use.

The invention discloses an evaluation method of a double-faced free-form surface lens. A lens-eye pupil is used as an optical system to evaluate global luminosity distribution and astigmatism distribution. The astigmatism distribution of the lens is subtraction of vectors of astigmatisms of the front and back surfaces of the lens. The evaluation method considers the optical system, namely the lens-eye pupil, under a state of wearing the lens, so that the quality of the lens can be quantitatively evaluated, an evaluated result is relatively reasonable and the optimal visuality of the lens can be obtained. Furthermore, in the designing process of the lens, the lens can be directly evaluated so that a lens designing period is shortened into steps of designing, evaluating, optimizing the designing and machining; and therefore, the cost is reduced and the evaluation method is convenient for industrial popularization and application.

The invention relates to a reactive power coordinated control algorithm for distributed photovoltaics of a distribution network based on an eleven-lattice graph. The algorithm comprises the following steps: (1) selecting a reactive power control adjusting method by adopting a selection control strategy of the eleven-lattice graph and using grid-connected point voltage and power factor as synthetic criteria; (2) enabling each adjustable photovoltaic power generation unit to have the same reactive power adjusting margin by adopting an equal proportion method, and distributing each photovoltaic power generation unit within the upper and lower limit range of reactive power according to the principle of identical offset; and (3) enabling each adjustable photovoltaic power generation unit to have the same power factor by adopting an equal power factor method, excluding nonadjustable photovoltaic power generation units and then calculating the total reactive power of a full station target according to a target instruction. The reactive power coordinated control algorithm for the distributed photovoltaics of the distribution network based on the eleven-lattice graph realizes coordinated control of the distributed photovoltaics, and ensures that the distribution network runs under normal and reasonable voltage.