Improved Shape Parameter Estimation in a Discrete Weibull Model

2012 ◽  
pp. 71-80 ◽  
Author(s):  
P. Araújo Santos ◽  
M. I. Fraga Alves
Keyword(s):  
Parameter Estimation ◽  
Shape Parameter ◽  
Weibull Model

scholarly journals Preventive Maintenance Strategy for Train Doors Based on the Competitive Weibull Theory

2020 ◽  
Author(s):  
deqiang he ◽  
Xiaozhen Zhang ◽  
Yanjun Chen ◽  
Jian Miao ◽  
Congbo Li ◽  
...  
Keyword(s):  
Parameter Estimation ◽  
Preventive Maintenance ◽  
Estimation Method ◽  
Weibull Model ◽  
Urban Rail Transit ◽  
Fuzzy Cluster ◽  
Rail Transit ◽  
Maintenance Strategy ◽  
Actual Situation ◽  
Urban Rail

Abstract In view of the problems of over-maintenance and under-maintenance in the current urban rail transit maintenance strategy and the reliability of single processing of fault data, which is often inconsistent with the actual situation, an incomplete preventive maintenance strategy based on the competitive Weibull model is proposed in this paper. To make the fault mechanism processing method for urban rail vehicles more accurate, fault feature attributes and fault information sequences are introduced to classify fault data. Fuzzy cluster analysis of vehicle fault data can be performed using the formula of the competitive Weibull model, and parameter estimation of the reliability model can be performed by combining it with the graph parameter estimation method. In addition, the fault rate increase factor and service age reduction factor are introduced into the maintenance strategy, and the optimal preventive maintenance cycle and maintenance times are obtained by combining maintenance and replacement according to reliability. A quantum-genetic intelligent algorithm is used to optimize the model-solving process. Finally, the maintenance of urban rail transit train doors is taken as an example. The results of this study show that compared with the traditional maintenance strategy, the reliability of the proposed maintenance strategy is closer to the actual situation. At the same time, the proposed maintenance strategy can effectively reduce the number of parked vehicles, reduce maintenance costs, and ensure the safety of train operation, maintenance economy and performance of tasks.

scholarly journals Identifying Influential Prognostic Factors of Death Hazard Rates in Patients with Chronic Kidney Disease (CKD) Using Weibull Model with Non-Constant Shape Parameter

2021 ◽  
Author(s):  
Seyede Solmaz Taheri ◽  
Ahmadreza Baghestani ◽  
Farzanehsadat Minoo ◽  
Anahita Saeedi
Keyword(s):  
Chronic Kidney Disease ◽  
Uric Acid ◽  
Prognostic Factors ◽  
Kidney Disease ◽  
Shape Parameter ◽  
Weibull Model ◽  
Hazard Rates ◽  
Time Interval ◽  
Stage Renal Disease ◽  
Constant Shape

Introduction: Chronic Kidney Disease (CKD) is a disease in which damaged kidneys could not remove waste material from the blood which could result in other health problems. The aim of this analysis was to identify significant laboratory prognostic factors on death hazard due to CKD. Methods: There were 109 patients with end-stage renal disease (ESRD) treated at Helal pharmaceutical and clinical complex. The survival time was set as the time interval from starting dialysis until death due to CKD. Age, gender and factors such as creatinine, cholesterol, uric acid, SGOT, SGPT, bilirubin, hemoglobin, potassium, ALP, HbA1C, ferritin, calcium, phosphorus, PTH and albumin were employed in this study. Weibull Distribution with non-Constant Shape Parameter versus constant Shape Parameter for the analysis were used. Results: Death due to CKD occurred in 29 (26.6%) of the patients. Sixty-seven (61.5%) had uric acid higher than 6.8 (mg/dl) and 39(35%) had phosphorus higher than 4.7 (mg/dl) which were poor prognoses. The incidence of death was 48.4%. Calcium<8.5 (mg/dl) (p=0.002), Calcium > 9.5 (mg/dl) (p=0.003), Albumin 4-6.3 (g/dl) (p=0.034), Phosphorus (p=0.022), hemoglobin<10 (g/dl) (p=0.043), hemoglobin>12.5 (g/dl) (p=0.006) and iPTH (p<0.001) were significant variables which had an effect on death hazard rates. Conclusion: The Weibull model with Non-Constant shape parameter was suggested to be more accurate for identifying risk factors, leading to more precise results, compared to constant shape parameter. Investigators mostly emphasize on the importance of Calcium, Albumin, Phosphorus, hemoglobin and iPTH for reducing hazard rates in CKD patients.  

scholarly journals On the Three-Parameter Weibull Distribution Shape Parameter Estimation

2021 ◽  
Vol 11 (3) ◽  
pp. 403-414
Author(s):  
Mahdi Teimouri ◽  
Arjun K. Gupta
Keyword(s):  
Parameter Estimation ◽  
Weibull Distribution ◽  
Shape Parameter ◽  
Distribution Shape

Parameter Estimation of the Shape Parameter of the Castillo–Hadi Model

2005 ◽  
Vol 33 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Hideki Nagatsuka ◽  
Toshinari Kamakura
Keyword(s):  
Parameter Estimation ◽  
Shape Parameter
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