Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
Likelihood and Empirical Bayes Modeling for Drought Via Copula
643
654
FA
One of the fundamental steps in management of drought involves identification and frequency analysis of its properties, e.g. duration and severity of drought. Regarding the high correlation among these factors, one must use a method that shows the relation and effects of these factors on drought analysis. Copula functions can be used to represent the dependency structure of several variables through a model. In this paper, we introduce the appropriate copula families for modeling drought phenomenon modeling. Then, their parameters would be estimated by maximum likelihood and Empirical Bayes methods and the most appropriate copula function for determining bivariate distribution of duration and severity of drought in Tehran stations is determined. Next, this copula function is used to model the drought phenomenon of Tehran for the period of 37 years from 1348 until 1384, Finaly the application of this model is represented in water supply management.
Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
Bootstrap Method for Mean Control Limits of Statistical Process
655
672
FA
Nasrollah
Iranpanah
Morteza
Mokhtari Moghadam
Univ. of Isfahan- Dep. of Statistics
Shewhart control charts are widely accepted as standard tools monitoring manufacturing statistical processes. The control charts have not applied, when the process distribution is not normal. The bootstrap is one of the resampling methods that can be used in statistical quality control without normality assumption. In most of papers, only the percentile bootstrap confidence interval is used for control limits. In this paper, we apply percentile bootstrap, bootstrap-t, bias corrected accelerated (BCa) and approximate bootstrap confidence interval (ABC) for mean control limits of statistical process. Then, the bootstrap confidence intervals are used and compared for mean control limits in simulation study. Finally, the bootstrap control limits are used for mean of CO2 data in Isfahan Zamzam factory.
Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
A Comparison of two Methods for Solving a Parabolic Inverse Problem
663
672
FA
s
bodaghi
a
Shahrezaee
In this article, we compare two procedures for solving a parabolic inverse heat problem subject to the over specified boundary condition .The first procedure is obtained by introducing transformation of unknown function and solving transformed problem by finite difference method. And the second method based on trace-type functional (TTF) formulation is examined on the solving of considered problem. Some numerical examples are presented
Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
A Generalization of Skew t-Normal Distribution and Modeling of Nickel Pollution in Shadegan Wetland
673
682
FA
A
Kheradmandi
M
Mohamadzadeh
N
Sanjari farsipur
The skew t-normal distribution has skewness and kurtosis coefficients with larger range than the skew-normal distribution can be used for modeling some asymmetric data in a number of applications. In this paper, a new generalization of the skew t-normal distribution and some of its properties are considered. Also, three theorems for constructing a new generalized skew t-normal distribution are represented. Next, the skew-normal, skew t-normal and new generalized skew t-normal distributions are applied to fit a suitable probability distribution to the Nickel pollution data of Shadegan wetland in south-west of Iran. Finally, suggestions and conclusion are given.
Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
جوابهای مجانبی مسئلۀ اغتشاشی تکین شامل معادلۀ مرتبۀ دوم خطی با ضرایب ثابت با شرایط کرانهای دیریکله
683
692
FA
مسائل لایۀ کرانهای، مدل ریاضی پدیدههای طبیعی و مسائل فیزیک و مهندسی هستند که در نقطه یا نقاطی که لایۀ کرانهای تشکیل میشود باید جوابهای مسئله را با تکنیکهای خاصی بررسی کرد تا جواب مسئله بهصورت یکنواخت و یکپارچه درآید. برای این مسئله ابتدا شرایط کافی برای وجود و عدم وجود تشکیل لایۀ کرانه ارائه میشود، سپس برای حالتی که در هر دو نقطه لایۀ کرانهای اتفاق میافتد، جواب تقریبی مسئله را با استفاده از روش بسطهای مجانبی سازگار شده در پنج مرحله بهصورت یکپارچه به دست میآوریم.
Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
Estimation of Survey Precision for Nonlinear Estimators
693
702
FA
In this paper, estimation of survey precision for nonlinear estimators is considered and an equation is presented based on sampling and nonsampling variances. Furthermore, by considering the response error model in surveys and the estimators of variance components, some relations are presented to computation of survey precision for nonlinear estimators. As an application case for the results, two typical data sets are considered and survey precisions of a nonlinear estimator are computed in the both data sets.
Quarterly Journal of Science Kharazmi University
10
1
2010
3
1
Weak topological centers of the second dual of Banach algebras
703
708
FA
In this paper, we study the left and right weak topological centers of the second dual of Banach algebra A and we establish some relationships of them with the Arens regularity of A.