Normal Distribution Curve Research Articles

POST EXAM ANALYSIS SELECTION OF HIGH AND LOW EXAM RESULT GROUPS BY NORMAL DISTRIBUTION CURVE

The key factor of an assessment is to minimize the errors by having a good reliability and validity of the assessment yardstick. To achieve high score in the test examinee must be aware about assessment cycle and use it in appropriate way in post exam analysis. Outcome of the results can be utilized as a constructive feedback in any given program. This cross-sectional study was conducted at department of Biochemistry, University of Rajarata. Multiple choice questions, structured essay type questions, objective structured practical examination, and continuous assessment was used in this study. Total number of students are 180 and was assessed for difficulty index, discrimination index, reliability, and standard error of measurement. In this study sample for analysis was used basically the examiner divides students into two groups (‘high’ and ‘low’) according to the score sheet of each student. Most of them are doing in a wrong way basically they divide high and low clusters as 25% each and considered upper quartile and lower quartile. In this study we compared it with the standard normal distribution curve where high and low groups are considered as 16% where is the standard. There is no significant difference among both clusters, and we recommend using the standard 16% as the high and low groups in post examination analysis. Keywords: difficulty index, post examination analysis, reliability of the examination, standard error of measurement

Growth and structure of pre-mature mixed stands of Scots pine created by direct seeding in the boreal zone

The purpose of the research is to analyse the successful creation of an artificial pine forest by seeding and develop recommendations for the guaranteed reproduction of pine stands in Northern European Russia. In recent decades, there has been a steady decline in the share of pine stands and their replacement with low-value and low-yielding tree species. We surveyed 12 permanent sample plots that were laid out in various variants of forest crops. The taxation parameters were obtained by a standard analysis of the experimental data. The evaluation parameters of the stands vary within the following limits: the average diameter of the pine trees varied from 21.9 to 30.9 cm; the total basal area of the pine varied from 19.1 to 38.8 m2∙ha–1; the average height of the pine varied from 20.1 to 26.8 m; the number of growing trees varied from 754 to 1 952 ha–1; the pines varied from 382 to 762 ha–1; the growing stocks of stands varied from 416 to 608 m3∙ha–1. The distribution of pine trees by thickness steps showed that all the studied samples were close to the normal distribution curve. The results of the correlation and multidimensional analyses showed that the creation method of the forest crops had a significant impact on the value of the taxation parameters. It was found that the best options for growing pure pine stands that can be recommended for practical production are plots with a large share of soil cultivation and the size of the seedbed.

Treatment of Popliteal Cyst through Radiofrequency Thermocoagulation under Ultrasound Guidance

Objective: The purpose of this study was to explore the clinical efficacy and security of the treatment of popliteal cyst through radiofrequency thermocoagulation (RFT) under ultrasound guidance. Methods: The clinical data of 35 patients with popliteal cyst, who were treated by RFT under ultrasound guidance from June 2019 to June 2020, were retrospectively analyzed. The Visual Analogue Scores (VAS) and the size of cyst before and after treatment were recorded at the first month, the third month, the sixth month. After six months, the recovery rate of Rauschning and Lindgren classification (R-L classification) level 0, 0 - I were counted. All the complications of the patients were observed. Results: 32 patients were followed up for six months. The scores and cyst sizes of each patient before and after the treatment were on a normal distribution curve. There was no significant difference in VAS scores before and after the treatment (P > 0.05). However, there was a significant difference in cyst sizes before and after the treatment (P 0.05). According to the R-L classification in 6 months after treatment: the recovery rate of class 0 was 62.5% and class 0 - I level was 87.5%. There were no serious complications in the process. Conclusion: Treatment of popliteal cyst through RFT under ultrasound guidance is a simple, easy, reliable method that is worthy of clinical promotion.

Effects of benzo(a)pyrene at environmentally relevant doses on embryo-fetal development in rats.

Studies have demonstrated that Benzo(a)Pyrene (BaP), a polycyclic aromatic hydrocarbon ubiquituous in the environment, can cause teratogenic effects. Since the majority of studies used in vitro models or high doses of BaP, this study evaluated the teratogenicity, reproductive and developmental performance of low doses of BaP through maternal and fetus examination after daily oral administration of BaP (0; 0.1; 1.0 or 10 μg/kg) to pregnant Wistar rats from Gestational day (GD) 6 to GD 15 (the organogenesis period). Pregnant rats did not exhibit clinical signs of toxicity during the exposure period. However, dams exposed to the lowest dose of BaP showed a reduction in the erythrocytes number and in the creatinine levels. The groups exposed to 0.1 and 1.0 μg/kg presented a decrease in placental efficiency, as well as an increase in placental weight. After fetal examination, the treated group with the lowest dose showed a reduced relative anogenital distance, while the curve of normal distribution of weight was changed in the highest dose group. In addition, anomalies evidenced by changes in the renal size and degree of fetal ossification were observed in treated-fetus. In conclusion, treatment with BaP during organogenesis at this dose level is detrimental to the normal development of fetuses.

Funciones cognitivas en la descendencia de pacientes con trastorno bipolar I

Objetivo: Describir las características neuropsicológicas de niños y adolescentes descendientes de padres con antecedentes de TB I, respecto a la aplicación de una prueba estandarizada de inteligencia.
 Materiales y métodos: Estudio observacional descriptivo de corte transversal, en donde los autores investigaron el Coeficiente Intelectual Total; Índice de compresión verbal; Índice de Razonamiento Perceptual; Índice de Memoria de trabajo; Índice de Velocidad de Procesamiento. Se evaluaron (n=30) descendientes al aplicar varias subpruebas de la Escala de inteligencia de Weschler para niños, (WISC –IV).
 Resultados: El Coeficiente Intelectual Total de los participantes con un 63,3% está por debajo del promedio de la curva de distribución normal, según la estandarización del test de inteligencia aplicado. Clasificando la tendencia de la muestra como un promedio normal bajo, en cuanto a la muestra evaluada. Los índices de memoria de trabajo y compresión verbal fueron las funciones cognitivas con puntuaciones más bajas en la muestra.
 Discusión: Nuestros hallazgos sugieren un riesgo en hijos de pacientes con TBI, que puede contribuir a un incremento cuantitativo de las alteraciones cognitivas, especialmente el índice de memoria de trabajo y compresión verbal. Estos hallazgos pueden sugerir un posible endofenotipo del TB I y su descendencia, en relación a la presentación temprana de alteraciones cognitivas en este grupo de riesgo. Dichos hijos podrían ser un punto de partida para realizar estudios que determinen predicción y realizar así un abordaje temprano.

Изменчивость высоты дуба черешчатого (Quercus robur L.) и клена остролистного (Acer platanoides L.) в полезащитной полосе

The organizing framework of adaptive landscape agriculture is protective afforestation. The study of the shelterbelt state is necessary for detection of their protective height due to the dramatically changing climatic conditions. The research purpose is to carry out the distribution of trees of English oak (Quercus robur L.) and Norway maple (Acer platanoides L.) with height for the stand structure evaluation, as well as to propose the measures for the condition improvement of English oak. The shelterbelt, the spatial structure of which was studied, is located in the vicinity of the village of Zolotarevka (65 km from the city of Lugansk). Archival data on the creation time and age of the studied forest shelterbelt were not revealed. Shelterbelts in the Lugansk region were created in accordance with the “Great Plan for the Transformation of Nature”, which was designed for 1949–1965. Sampling areas were laid out in accordance with the industrial standard OST 56-69–83. The composition of the shelterbelt, the diameter and average height of the trees were determined based on the results of enumerative valuation. The coefficients of skewness and kurtosis of stands of the studied species were calculated by the standard methods of biometrics. The distribution of Norway maple and English oak trees with height was checked with the normal distribution of trees in the plantation according to the Shapiro-Wilk test. The authors revealed that arithmetic and valuation mean heights of the stands of English oak and Norway maple on two permanent sampling areas differ slightly. It was found that the stand of Norway maple on the first and second sampling areas is characterized by positive right-side symmetry and positive kurtosis. Analyzing the stand condition, it is arguable that the coefficient of skewness of the English Oak stand on both areas is not the same in sign and numerical value: on the first sampling area – leftside negative (As = –2.026) and on the second – right-side positive (As = 0.973). The authors pay particular attention to the fact that the value of the coefficient of kurtosis of the English Oak stands is the highest on the first sampling area – 3.044. On the basis of the Shapiro-Wilk test it is shown that the curve of distribution of the Norway maple stands with height on the first and second sampling areas does not correspond to the normal distribution curve for the plantations. While the curve of distribution of the English Oak stands with height on the second sampling area is close to the indicator of the Shapiro-Wilk test for normal stands and is 0.823 (for p = 0.05, W = 0.842, n = 10).

Local initiatives for green space using Poland's Village Fund: evidence from Lodzkie voivodeship

Abstract Poland's Village Fund (Fundusz Sołecki) is an instrument operating at the level of the so-called sołectwo, into which local-administration units known as gminas may be further sub-divided. These are therefore auxiliary administrative units in rural areas whose receipt of means from the Fund in question allows for the activation of local communities. Against that background, the research detailed here sought to examine Village Fund by reference to the greenspace-related projects pursued using it in the rural gminas of Łódzkie Voivodeship. Additional aspects are the classification of the tasks carried out, presentation of the statistical analysis applied, and consideration of the breakdown obtained for indicators relating to the share of funds allocated to green areas – by reference to the properties of the normal distribution curve.

Plant components affect bacterial biofilms development by altering their cell surface physicochemical properties: a predictability study using Actinomyces naeslundii.

We hypothesized that the initial events leading to biofilm formation by bacteria, in general, are predominantly mediated by cell surface physicochemical interactions, and that natural products can impact the process by altering cell surface physicochemical properties. We exemplified this phenomenon using Actinomyces naeslundii as the model organism, and using tea products to modify its cell surface physicochemical properties. To test the hypothesis, a non-linear multiple regression model incorporating a normal distribution curve was constructed to explain the impact of tea extracts on the physiochemical processes of biofilm formation by A. naeslundii. The model utilized tea extract-induced changes in cell surface physicochemical properties as independent variables, and the corresponding biofilm formation as a dependent variable. Five different tea extracts were used to treat A. naeslundii, and their impact on the cell surface hydrophobicity, charge, auto-aggregation, attachment and biofilm formation on four different hard surfaces were measured and the data were used to construct the model. The established model was then tested in independent experiments involving other plant extracts and purified phytochemicals. Experimental results showed that the tea extracts significantly reduced cell surface hydrophobicity (by up to 21.3%), increased cell surface charge and auto-aggregation (by up to 4.5mV and 14.9%, respectively), inhibited attachment (by 0.6-2.5 log CFU cm-2) and affected biofilm formation (by up to 0.6 log CFU cm-2). The model indicated that both cell surface hydrophobicity and charge played an important role in bacterial auto-aggregation and attachment, and that the latter two phenomena significantly correlated with subsequent biofilm development. The accuracy of the model construct was approximately 64%. This modelling approach can be employed for other microbial colonization systems to predict biofilm formation, and to study the impact of cell surface physicochemical properties in biofilm development.

The B-mode sonographic evaluation of the post-caesarean uterine wall and its methodology: A study protocol.

The aim of this study is to utilize the niche measurement guidelines outlined by Jordans et al. in order to establish normal values and accurate description of caesarean section scars in a normal population. After defining the normal distribution, abnormal pregestational scar characteristics will be identified for predicting adverse pregnancy outcomes. This is a prospective observational multicenter clinical study where women with a history of only one caesarean section and yet open family planning are enrolled. The uterine length, cervical length, niche length, niche depth, niche width, residual myometrial thickness, endometrial thickness, scar to internal os distance, anterior myometrial thickness superior and inferior to the scar and the posterior myometrial thickness opposite the scar, superior and inferior to it are measured in a pregestational uterus. The lower uterine segment is measured over a length of 3 cm during subsequent pregnancy and followed up until delivery. Data from 500 patients will yield normal distribution curves for all predefined measurements. Establishing a correlation between deviations from the normal measures and adverse events would be instrumental for counseling women regarding subsequent pregnancy and mode of delivery. This study will demonstrate the changes of the post-caesarean scar from a non-pregnant uterus until delivery and can confirm the importance of the scar characteristics in predicting pregnancy outcome.

Modified sub-gradient based combined objective technique and evolutionary programming approach for economic dispatch involving valve-point loading, enhanced prohibited zones and ramp rate constraints

A security constrained non-convex power dispatch problem with prohibited operation zones and ramp rates is formulated and solved using an iterative solution method based on the feasible modified sub-gradient algorithm (FMSG). Since the cost function, all equality and inequality constraints in the nonlinear optimization model are written in terms of the bus voltage magnitudes, phase angles, off-nominal tap settings, and the Susceptance values of static VAR (SVAR) systems, they can be taken as independent variables. The actual power system loss is included in the current approach and the load flow equations are inserted into the model as the equality constraints. The proposed modified sub gradient based combined objective technique and evolutionary programming approach (MSGBCAEP) with as decision variable and cost function as fitness function is tested on the IEEE 30-bus 6 generator test case system. The absence of crossover operation and adoption of fast judicious modifications in initialization of parent population, offspring generation and normal distribution curve selection in EP enables the proposed MSGBCAEP approach to ascertain global optimal solution for cost of generation and emission level shown in Table 6 and displayed in Figure 2 and Figure 3 respectively.

Climatic variability at Gangtok and Tadong weather observatories in Sikkim, India, during 1961\u20132017

The present study documents the long-term trends in the temperature and precipitation of a poorly represented region, the Sikkim, eastern Himalaya using the Mann–Kendall non-parametric test and the Sen’s slope estimator. Additionally, the normal distribution curves and Cusum charts have been used to identify the shifts in extreme events and to detect the points of change in the climatic data series for robust analysis. The minimum temperatures recorded a positive trend in Gangtok (0.036 ˚C year−1 from 1961 to 2017) as well as in Tadong (0.065 ˚C year−1 from 1981 to 2010) stations, while the maximum temperatures showed no trend in Tadong station from 1981 to 2010 which is consistent with the trend in Gangtok station for the overlapped period. However, it was negative for the overall assessed period (− 0.027 ˚C year−1 from 1961 to 2017) in Gangtok. The average temperatures in Gangtok recorded no trend whereas a positive trend (0.035 ˚C year−1 from 1981 to 2010) was observed at Tadong station. A similar positive trend in the average temperatures has been detected at Gangtok also for the overlapped period. Accelerated warming was noticed during the last two decades with an increase in the probability of extreme events of temperatures (minimum, maximum, average) at the higher end. Precipitation was found to be more variable across the observed period and suggested no trend in the study area.

Generalized normal distribution optimization and its applications in parameter extraction of photovoltaic models

The accuracy of extracting the unknown parameters of photovoltaic models is closely related with the effectiveness of modeling, simulating, and controlling photovoltaic systems. Metaheuristics have been widely used for improving the accuracy of extracting the unknown parameters of photovoltaic models. Despite the success of such techniques in this application area, they require parameter adjustment, which will restrict their applications especially for non-expert users. This is the motivation of this work, in which a novel metaheuristic is proposed called generalized normal distribution optimization, the proposed method is inspired by the generalized normal distribution model; each individual uses a generalized normal distribution curve to update its position. Unlike the majority of metaheuristics, the proposed method only needs the essential population size and terminal condition to solve optimization problems. In order to benchmark the performance of the proposed method, it is employed to extract the unknown parameters of three photovoltaic models including single diode model, double diode model and photovoltaic module model. The solutions obtained by the proposed method are compared with those of ten state-of-the-art metaheuristic algorithms and some recent reported solutions. Experimental results demonstrate the excellent performance of the proposed method for parameter extraction of the applied photovoltaic models in terms of quality and stable of the obtained solutions.11The souce code of GNDO is publicly available at https://au.mathworks.com/matlabcentral/fileexchange/79526-the-source-code-for-gndo.

Statistical analysis and characteristics of hospital medical waste under novel Coronavirus outbreak

One of thesources of infection as a result of coronavirus disease treatment is the medical waste generated during the health care activities. Since the registration of the first infected case of coronavirus in Jordan the daily number of patients fluctuated from as low as zero to as high as 40 with a recovery ratio and case fatality risk of 39% and 1.7%, respectively. The main objective of the present study is to carry out statistical analysis and assess the generation rates and the composition of the medical waste generated during the treatment of coronavirus pandemic with reference to a major tertiary care hospital in Jordan. Data onthe daily generated waste, number of the admitted patients and on the amounts of consumables like various personal protective equipment, testing kits, and disinfectant used during the treatment of coronavirus disease was obtained. Data was subjected to descriptive statistical analysis to find the average generation rates, 3 days moving average, as well as the frequency distribution of the generated amounts. During 25 days' period, King Abdullah University Hospital has admitted 95 infected patients by coronavirus. The amount of the average rate of the medical waste generated as a result of coronavirus treatment was found to be 14.16 kg/patient/day and 3.95 kg/bed/day, which are more than tenfold higher than the average generation rate during the regular operational days of the hospital. Frequency analysis of the data revealed that the medical waste generation follows log normal distribution with correlation coefficient of 0.89. The distribution is distorted to the right and flatter than the normal distribution curve as judged by the skewness and kurtosis coefficients, respectively, which indicates deviation from normality.

Generation of typical meteorological years for 33 locations in Greece: adaptation to the needs of various applications

A typical meteorological year (TMY) is a set of meteorological and solar radiation parameters usually consisting of hourly values in a year for a given geographical location. Such TMYs have been derived in many countries for various applications. In Greece, TMYs have been generated mainly for Athens. The present work derives TMYs for 33 locations in Greece distributed all over the country and covering its 4 climatic zones defined for energy purposes. The TMYs are based on meteorological data collected from the Hellenic National Meteorological Service network in Greece in the period 1985–2014. The solar radiation needed in the generation of the TMYs is derived by using the meteorological radiation model. The TMY at every one of the 33 locations is provided in 5 versions to adapt to the applications of meteorology-climatology, bio-meteorology, agro-meteorology-hydrology, photovoltaics, and energy design of buildings. The 5 versions of the TMYs are generated following the modified Sandia National Laboratories method. After their generation, each version of the TMYs at any of the 33 locations is compared with the annual- and monthly-averaged values of the selected parameters of the initial 30-year database. The comparison shows that the errors (differences) do not usually exceed 5%, thus supporting the fact that the so-derived TMYs are representative of the sites selected. Also, the distribution of the errors follows the normal distribution curve.

Numerical investigation of the effect of variation of gas mixture ratio on density distribution of etchant species (Br, Br+, Cl, Cl+, and H) in HBr/Cl2/Ar plasma discharge

A self-sustained fluid model is used to study the effect of variation of noble gas fraction (Ar) and variation of gas mixture ratio (HBr/Cl2/Ar) on density distribution of important etchant species (Br, Br+, Cl, Cl+, and H) in HBr/Cl2/Ar capacitive coupled plasma discharge that is being vastly used for dry etching of Si, GaAs, GaSb and other group III and IV semiconductor materials. A comprehensive set of 80 reactions in this plasma discharge is presented which contains electron impact reactions, neutral–neutral reactions, ion–ion reactions, and charge transfer reactions. Based on simulation results, it is found that densities of neutral species have normal distribution curve; density is higher at center of the reactor and decreases as we move towards electrode surface, while densities of charged species follow bimodal distribution in which peaks occur near electrodes. Furthermore, the addition of Ar in HBr/Cl2 causes electron density to increase which promotes ionization and dissociation. It was found that at constant supply of Cl2 gas, by increasing Ar fraction (HBr/Cl2/Ar from 80/10/10 to 10/10/80) densities of Br, Br+ and H will go down and at constant supply of Ar gas, raising Cl2 fraction in feedback gases (HBr/Cl2/Ar from 70/20/10 to 20/70/10) promoted the production of Cl and Cl+ while densities of Br, Br+, and H are dropped-off. Hence, densities and fluxes of important etchant species – for chemical vs. physical etching – can be controlled by tuning of mixture ratio.

A Novel Seepage Safety Monitoring Model of CFRD with Slab Cracks Using Monitoring Data

The traditional regression model usually simulates the influence of water pressure and rainfall in the early stage based on experience, but it is not suitable. To solve this problem, the normal distribution curve is used to simulate the lagging effect of water pressure and rainfall on dam seepage. In view of problem of slab cracks, the influence of cracks on seepage is analyzed. In this paper, a safety monitoring model for concrete face rockfill dam (CFRD) seepage with cracks considering the lagging effect is proposed, in which slab cracks are considered as an influencing factor. The radial basis function neural network (RBFNN) optimized by genetic algorithm (GA) is used to establish a safety monitoring model for a CFRD seepage. Seepage of the dam is predicted by this model, whose results are similar to the monitoring data, which indicates that the method has certain applicability. Through the analysis of the proportion of factors affecting CFRD seepage, it is found that the rainfall component has the greatest impact on the total seepage, accounting for more than 50%, and the crack component accounts for about 10%. Finally, through the cloud model, the monitoring index of CFRD seepage is worked out, which has certain guiding significance for the treatment of abnormal seepage monitoring data.

Vehicle Lateral Wander Measures Using Ultrasonic Sensors

This paper evaluates the measurement of vehicle lateral wander using ultrasonic sensors. Measurements were made on different sections of the Costa Rican National Road Network. The recorded data allowed to determine the cumulative frequency distribution, lateral wander data and a confidence interval for the measurements. In some routes, where the sample size is greater than 70 vehicles, the distribution of the lateral wander data adjusted to a normal distribution. However, in several cases the data does not resemble a normal distribution curve, or other distributions reported in the literature. Finally, an Android app was developed to automate the data collection process using the ultrasonic sensor setup, simplifying the measurement process. From the cumulative frequency results, obtained with the ultrasonic sensors, it was determined that most vehicles travel between 50 and 150 cm from the edge of the road. In order to validate the data, the results obtained with the ultrasonic sensor setup were compared with the results obtained by image analysis of video recordings. These image analysis is possible due to pavement markings every five centimeters on the pavement from the lane edge. The results from video recordings and ultrasonic sensors show a high coefficient of correlation.

Do the Mega and Titan Tests Yield Accurate Results? An Investigation into Two Experimental Intelligence Tests

The Mega and Titan Tests were designed by Ronald K. Hoeflin to make fine distinctions in the intellectual stratosphere. The Mega Test purported to measure above-average adult IQ up to and including scores with a rarity of one in a million of the general population. The Titan Test was billed as being even more difficult than the Mega Test. In this article, these claims are subjected to scrutiny. Both tests are renormed using the normal curve of distribution. It is found that the Mega Test has a higher ceiling and a lower floor than the Titan Test. While the Mega Test may thus seem preferable as a psychometric instrument, it is somewhat marred by a number of easy items in its verbal section. Although official scores reported to test-takers are too high, it is likely that the Mega Test does stretch to the one in a million level. The Titan Test does not. Testees who had previously taken standard intelligence tests achieved average scores of 135–145 IQ on those. Since the mean of all scores on the Mega and Titan Tests was found to be IQ 137 and IQ 138, respectively, testees had considerable scope to find their true level without ceiling effects. Both are unusual and non-standard tests which require a great deal of effort to complete. Nevertheless, they deserve consideration as they represent an inventive experimental method of measuring the very highest levels of human intelligence and have been taken by enough subjects to allow norming.

Research of Wireless Congestion Control Algorithm Based on EKF

The random variation of bandwidth in wireless networks causes some significant challenges to the congestion control protocols based on bandwidth estimation. In this paper, a wireless congestion control scheme based on extended Kalman filtering and bandwidth (CSEKB) is proposed. The CSEKB can effectively perceive the bandwidth oscillation of wireless networks and distinguish the type of packet loss by establishing a noise perception factor. According to the congestion factor, the congestion control parameters are adjusted to correspondingly improve the performance of the wireless network. Moreover, the variation trend of the size of the congestion window presents a law of similar normal distribution curve, which has a certain degree of local symmetry. The CSEKB was implemented in Network simulator 3 (NS3) and compared with TCP Westwood (TCPW), CUBIC, and extended Kalman filtering-based bandwidth estimation (EBE). Through extensive simulation studies, the proposed CSEKB demonstrated the significant performance in wireless networks. First, the CSEKB can achieve congestion control based on the accurate prediction of available bandwidth, and improve average throughput and link utilization. In addition, the CSEKB has good fairness and friendliness compared with several other well-known congestion control methods.

Predicting Hidden Danger Quantity in Coal Mines Based on Gray Neural Network

The hidden danger is the direct cause of coal mine accidents, and the number of hidden dangers in a certain area not only reflects the current safety situation, but also determines the development trend of safety production in this area to a large extent. By analyzing the formation and development law of the hidden dangers and hidden danger accident-induced mechanism in coal mines, it is concluded that there are some objective laws in the process of occurrence, development, weakening, and even stabilization of hidden dangers in a certain area. The development of the number of hidden dangers for a coal mine generally presents the law of similar normal distribution curve, with a certain degree of partial symmetry. Many years of hidden danger elimination in coal mines will accumulate large-scale hidden danger data. In this paper, by using the average value of hidden danger quantity in consecutive months to weaken the oscillation of hidden danger quantity sequence, and combining with gray model (1,1) and the neural network of extreme learning machine, and employing big data of hidden dangers available, a hidden danger quantity prediction model based on the gray neural network was established, and the experimental analysis and verification carried out. The results show that the model can achieve good prediction effect on the number of hidden dangers in a coal mine, which not only reflects the complex gray system behavior of hidden dangers of a coal mine, but also can predict dynamically. The safety management efficiency and emergency capacity of the coal mine enterprise will be greatly improved.