• Title/Summary/Keyword: weibull distribution

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New approach to calculate Weibull parameters and comparison of wind potential of five cities of Pakistan

  • Ahmed Ali Rajput;Muhammad Daniyal;Muhammad Mustaqeem Zahid;Hasan Nafees;Misha Shafi;Zaheer Uddin
    • Advances in Energy Research
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    • v.8 no.2
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    • pp.95-110
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    • 2022
  • Wind energy can be utilized for the generation of electricity, due to significant wind potential at different parts of the world, some countries have already been generating of electricity through wind. Pakistan is still well behind and has not yet made any appreciable effort for the same. The objective of this work was to add some new strategies to calculate Weibull parameters and assess wind energy potential. A new approach calculates Weibull parameters; we also developed an alternate formula to calculate shape parameters instead of the gamma function. We obtained k (shape parameter) and c (scale parameter) for two-parameter Weibull distribution using five statistical methods for five different cities in Pakistan. Maximum likelihood method, Modified Maximum likelihood Method, Method of Moment, Energy Pattern Method, Empirical Method, and have been to calculate and differentiate the values of (shape parameter) k and (scale parameter) c. The performance of these five methods is estimated using the Goodness-of-Fit Test, including root mean square error, mean absolute bias error, mean absolute percentage error, and chi-square error. The daily 10-minute average values of wind speed data (obtained from energydata.info) of different cities of Pakistan for the year 2016 are used to estimate the Weibull parameters. The study finds that Hyderabad city has the largest wind potential than Karachi, Quetta, Lahore, and Peshawar. Hyderabad and Karachi are two possible sites where wind turbines can produce reasonable electricity.

Influence Analysis of Sampling Points on Accuracy of Storage Reliability Estimation for One-shot Systems (원샷 시스템의 저장 신뢰성 추정 정확성에 대한 샘플링 시점의 영향 분석)

  • Chung, Yong H.;Oh, Bong S.;Lee, Hong C.;Park, Hee N.;Jang, Joong S.;Park, Sang C.
    • Journal of Applied Reliability
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    • v.16 no.1
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    • pp.32-40
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    • 2016
  • Purpose: The purpose of this study is to analyze the effect of sampling points on accuracy of storage reliability estimation for one-shot systems by assuming a weibull distribution as a storage reliability distribution. Also propose method for determining of sampling points for increase the accuracy of reliability estimation. Methods: Weibull distribution was divided into three sections for confirming the possible to estimate the parameters of the weibull distribution only some section's sample. Generate quantal response data for failure data. And performed parameter estimation with quantal response data. Results: If reduce sample point interval of 1 section, increase the accuracy of reliability estimation although sampling only section 1. Even reduce total number of sampling point, reducing sampling time interval of the 1 zone improve the accuracy of reliability estimation. Conclusion: Method to increase the accuracy of reliability estimation is increasing number of sampling and the sampling points. But apply this method to One-shot system is difficult because test cost of one-shot system is expensive. So propose method of accuracy of storage reliability estimation of one-shot system by adjustment of the sampling point. And by dividing the section it could reduce the total sampling point.

Weibull Statistical Analysis of Elevated Temperature Tensile Strength and Creep Rupture Time in Stainless Steels (스테인리스 강의 고온 인장강도와 크리프 파단시간의 와이블 통계 해석)

  • Jung, W.T.;Kim, Y.S.;Kim, S.J.
    • Journal of Power System Engineering
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    • v.14 no.4
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    • pp.56-62
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    • 2010
  • This paper is concerned with the stochastic nature of elevated temperature tensile strength and creep rupture time in 18Cr-8Ni stainless steels. The Weibull statistical analysis using the NRIM data sheet has been performed to investigate the effects of variability of the elevated temperature tensile strength and creep rupture time on the testing temperature. From those investigations, the distributions of temperature tensile strength and creep rupture time were well followed in 2-parameter Weibull. The shape parameter and scale parameter for the Weibull distribution of tensile strength were decreased with increasing the testing temperature. For the creep rupture time, generally, the shape parameter were decreased with increasing the testing temperature.

Statistical Analysis using Weibull Distribution on the Dielectric Breakdown Strength of High Density Polyethylene Films (HDPE필름 절연파괴강도의 Weibull분포에 의한 통계적 해석)

  • Kang, Moo-Sung;Kang, Dae-Yong;Park, Dae-Hee
    • Proceedings of the KIEE Conference
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    • 1997.07e
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    • pp.1702-1704
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    • 1997
  • 본 논문은 HDPE 필름의 절연성능을 평가하기 위하여 절연파괴강도의 결과를 Weibull분에 적용하였다. 각 절연파괴강도의 Weibull분포로부터 형의 모수를 구하였다. 또한 Weibull분포의 활용은 2개 및 3개의 모수법을 각각 적용시켜 절연파괴강도의 평가를 하였다. HDPE 필름을 열화시켜, 형의 모수변화를 비교하였다. 이와같은 Weibull분포의 활용은 절연성능과 수명의 평가를 통계적으로 평가코져 한다.

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Prediction of Stand Volume and Carbon Stock for Quercus variabilis Using Weibull Distribution Model (Weibull 분포 모형을 이용한 굴참나무 임분 재적 및 탄소저장량 추정)

  • Son, Yeong Mo;Pyo, Jung Kee;Kim, So Won;Lee, Kyeong Hak
    • Journal of Korean Society of Forest Science
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    • v.101 no.4
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    • pp.599-605
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    • 2012
  • The purpose of this study is to estimate diameter distribution, volume per hectare, and carbon stock for Quercus variabilis stand. 354 Quercus variabilis stands were selected on the basis of age and structure, the data and samples for these stands are collected. For the prediction of diameter distribution, Weibull model was applied and for the estimation of the parameters, a simplified method-of-moments was applied. To verify the accuracy of estimates, models were developed using 80% of the total data and validation was done on the remaining 20%. For the verification of the model, the fitness index, the root mean square error, and Kolmogorov-Smirnov statistics were used. The fitness index of the site index, height, and volume equation estimated from verification procedure were 0.967, 0.727, and 0.988 respectively and the root mean square error were 2.763, 1.817, and 0.007 respectively. The Kolmogorov-Smirnov test applied to Weibull function resulted in 75%. From the models developed in this research, the estimated volume and above-ground carbon stock were derived as $188.69m^3/ha$, 90.30 tC/ha when site index and stem number of 50-years-old Quercus variabilis stand show 14 and 697 respectively. The results obtained from this study may provide useful information about the growth of broad-leaf species and prediction of carbon stock for Quercus variabilis stand.

A Bayesian Approach to Periodic Preventive Maintenance Policy (주기적인 예방보전정책의 베이즈 접근방법)

  • 한성실;정기문;권영섭
    • Journal of Korean Society for Quality Management
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    • v.29 no.3
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    • pp.39-48
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    • 2001
  • Preventive maintenance(PM) is an action taken on a repairable system while it is still operating, which needs to be carried out in order to keep the system at the desired level of successful operation. In this paper, we consider a Bayesian approach to determine an optimal periodic preventive maintenance policy. When the failure time is Weibull distribution with uncertain parameters, a Bayesian approach is established. Some numerical examples are presented for illustrative purpose.

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Parametric Empirical Bayes Estimators with Item-Censored Data

  • Choi, Dal-Woo
    • Journal of the Korean Data and Information Science Society
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    • v.8 no.2
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    • pp.261-270
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    • 1997
  • This paper is proposed the parametric empirical Bayes(EB) confidence intervals which corrects the deficiencies in the naive EB confidence intervals of the scale parameter in the Weibull distribution under item-censoring scheme. In this case, the bootstrap EB confidence intervals are obtained by the parametric bootstrap introduced by Laird and Louis(1987). The comparisons among the bootstrap and the naive EB confidence intervals through Monte Carlo study are also presented.

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Variables Sampling Plans for the Weibull Distribution under Progressive Failure Censoring (점진적 정수 중단 하에서의 와이블분포에 대한 계량형 샘플링검사)

  • Lee, Sang-Ho;Jeon, Chi-Hyeok;Balamurali, S.
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2005.05a
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    • pp.922-926
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    • 2005
  • Progressively censored variables sampling plans are proposed for the lot acceptance of parts whose life follows Weibull distribution with known shape parameter. Progressive type-II censoring gives us not only time to failure but also degradation information. So, one can construct more flexible and more cost effective sampling plans. Design parameters of our sampling plan are determined by using the usual two-point approach.

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A Note on Sudden Death Tests (sudden death 시험에 대한 고찰)

  • Seo, Sun-Keun
    • Journal of Applied Reliability
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    • v.12 no.3
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    • pp.139-152
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    • 2012
  • Successive and simultaneous sudden death tests are compared with the complete and Type II censored samples in terms of expected test duration and Total Time on Test(TTT) subject to the same number of failures in order to maintain the equal statistical precision under Weibull lifetime distribution with known shape parameter. Also, two sudden death tests under a proposed cost model are discussed and a numerical example is provided to illustrate the use of the proposed cost model.

Impacts on the Deteriorative Breakdown Characteristics by the Void of Polyethyleme (Polyethylene의 공극이 절연파괴특성에 미치는 영향)

  • 정영순
    • 전기의세계
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    • v.26 no.3
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    • pp.59-62
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    • 1977
  • This study is to investigate the v-t characteristics gained by means of the Weibull distribution and to analyze the characteritics of fatigue breakdown caused by the A-C voltage of cross-linked polyethylene with and without void. By the results, it has in most cases reveald deteriorative breakdown in case of none-void, and that random breakdown or complex Weibull distribution of deteriorative breakdown and random breakdown in case of with void.

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