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Distribution-free prediction intervals for order statistics based on record coverage
Jafar Ahmadia,N. Balakrishnan 한국통계학회 2011 Journal of the Korean Statistical Society Vol.40 No.2
In this paper, based on the largest and smallest observations at the times when a new record of either kind (upper or lower) occurs, we discuss the prediction of future order statistics. The proposed prediction intervals are distribution-free in that the corresponding coverage probabilities are known exactly without any assumption about the parent distribution other than that it being continuous. An exact expression for the prediction coefficient of these intervals is derived. Similarly, prediction intervals for future records based on observed order statistics are also obtained. Finally, two real-life data, one involving the average July temperatures in Neurenburg, Switzerland, and the other involving the amount of annual rainfall at the Los Angeles Civic Center, are used to illustrate the procedures developed here.
Jafar Soltani,Yasser Hassani,Navid Reza Abjadi 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents a novel isolated three-phase induction generator with constant frequency and adjustable output voltage using a three-phase STATic COMpensator (STATCOM). The proposed electricity generating system consists of a dual stator-winding and STATCOM. In this generator, there are two sets of windings to be embedded in the stator slots. One, referred to as the 3-phase power winding, supplies power to load and the other, called 3-phase excitation winding is connected to a space vector modulation (SVM) voltage source invertor (VSI). Due to magnetic coupling between stator windings, active power transfer occurs between them. This active power causes serious disturbance in generator performance. A closed-loop controller for STATCOM is used to supply only requested reactive power and prevent active power transfer. In this paper, a hydraulic turbine and its governing system used for controlling requested active power amount by load are modelled. In comparison with other isolated induction generators, important advantages of this one are constant frequency independent from prime mover speed and adjustable output voltage.
Jafar Ahmadia,Elham Basiri,S.M.T.K. MirMostafaee 한국통계학회 2016 Journal of the Korean Statistical Society Vol.45 No.2
Choosing the sample size is a problem faced by anyone doing a survey of any type. ‘‘What sample size do we need?’’ is one of the most frequently asked questions of statisticians. The answer always starts with ‘‘It depends on...’’. In this paper, we respond to this question by considering two criteria, total cost of experiment and mean squared prediction error in prediction problem. Towards this end, we discuss the problem of Bayesian predicting future observations from an exponential distribution based on an observed sample, when the information sample size is fixed as well as a random variable. Some distributions for the information sample size are considered and then for each case we find the parameter of distribution of the information sample size, such that the point predictor of a future order statistic has minimum mean squared prediction error when the total cost of experiment is bounded. To show the usefulness of our results, we present a simulation study. Finally, we apply our results to some real data sets in life testing.
MoS2 nanosheet as a promising nanostructure membrane for gas separation
Jafar Azamat,Alireza Khataee 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.66 No.-
We investigated the capability of MoS2 membrane for separation of natural gas mixtures, including CH4/CO2, CH4/H2S and CH4/CO2/H2S mixtures. The permeation mechanisms of the gas molecules through the pore of MoS2 membrane were revealed by gas molecular structure analyzing, orientation of gas molecule in the simulation system and density map. The energy barrier for three types of gas molecules was calculated and showed that gas molecules with the low energy barrier could pass through the MoS2 pore. Hence, the present study introduces MoS2 membrane as a new nanostructure membrane for gas separation in the industries.
Jafar Mahmoudi,Mohammad Nader Lotfollahi,Ali Haghighi Asl 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.24 No.-
Benzene reduction in gasoline was investigated with propylene over synthesized mesoporous H-Al- MCM-41 with Si/Al = 15, 29 and 42 as catalysts in order to produce more environmental friendly gasoline. The resulting catalysts were characterized by XRF, XRD, FTIR, TGA, BET and TPD-NH3 techniques. The results of alkylation of C6-cut obtained from gasoline indicated that the synthesized mesoporous H-AL-MCM-41 with Si/Al = 15 is the most active catalyst among the synthesized catalysts due to high crystallinity, favorable textural properties and large bronsted acidity. The higher conversion of benzene (47.88%) was observed over H-Al-MCM-41 with Si/Al = 15 at B/P = 1 and T = 200 8C.
A Hybrid Decision-Making Model for Selecting Container Seaport in the Persian Gulf
Jafar SAYAREH,Hamed REZAEE ALIZMINI 한국해운물류학회 2014 The Asian journal of shipping and Logistics Vol.30 No.1
Ports have always played a vital role in international transportation. Port selection decision is a process that requires consideration of many important and relevant criteria. The selection of the influential decision-making criteria is also a significant and vital issue which demands cautious thoughts. The main objective of this paper is to weigh the most dominant decision-making criteria by Technique for Order Preference to Similarity by Ideal Solution (TOPSIS) and select an optimised container seaport in the Persian Gulf by Analytical Hierarchy Process (AHP) according to decisive port selection factors. This paper presents an extensive review of port selection decision-making attributes in different past studies. Finally, by using TOPSIS and AHP, the findings of this research suggest that the working time, stevedoring rate, safety, port entrance, sufficient draft, capacity of port facilities, operating cost, number of berths, ship chandelling, and international policies are critical factors for selecting container seaport in the Persian Gulf.