Preferred Language
Articles
/
jeasiq-1824
Applying some hybrid models for modeling bivariate time series assuming different distributions for random error with a practical application
...Show More Authors

Abstract

  Bivariate time series modeling and forecasting have become a promising field of applied studies in recent times. For this purpose, the Linear Autoregressive Moving Average with exogenous variable ARMAX model is the most widely used technique over the past few years in modeling and forecasting this type of data. The most important assumptions of this model are linearity and homogenous for random error variance of the appropriate model. In practice, these two assumptions are often violated, so the Generalized Autoregressive Conditional Heteroscedasticity (ARCH) and (GARCH) with exogenous variables (GARCHX) are applied to analyze and capture the volatility that occurs in the conditional variance of a linear model. Since time series observations rarely have linear or nonlinear components in nature or usually included together. Therefore, the main purpose of this paper is to employ the hybrid model technique according to Zhang methodology for hybrid models to combine the linear forecasts of the best linear model of ARMAX models and the nonlinear forecasts of the best nonlinear models of (ARCH, GARCH & GARCHX) models and thus increase the efficiency and accuracy of performance forecasting future values of the time series.

This paper is concerned with the modeling and building of the hybrid models (ARMAX-GARCH) and (ARMAX-GARCHX), assuming three different random error distributions: Gaussian distribution, Student-t distribution, as well as the general error distribution and the last two distributions were applied for the purpose of capturing the characteristics of heavy tail distributions which have a Leptokurtic characteristic compared to the normal distribution. This research adopted a modern methodology in estimating the parameters of the hybrid model namely the (two-step procedure) methodology. In the first stage, the parameters of the linear model were estimated using three different methods: The Ordinary Least Squares method (OLS), the Recursive Least Square Method with Exponential Forgetting Factor (RLS-EF), and the Recursive Prediction Error Method (RPM). In the second stage, the parameters of the nonlinear model were estimated using the MLE method and employing the numerical improvement algorithm (BHHH algorithm).

 

 

 

The hybrid models have been applied for modeling the relationship between the exogenous time series represented by the exchange rate and the endogenous time series represented by the unemployment rate in the USA for the period from (January 2000 to December 2017 i.e. 216 observations), and also the out-of-sample forecasts of unemployment rate in the last twelve values of (2018). The forecasting performance of the hybrid models and the competing individual model was also evaluated using the loss function accuracy measures (MAPE), (MAE), and the robust (Q-LIKE). Based on statistical measurements, the results showed the hybrid models improved the accuracy and efficiency of the single model. () hybrid model error whose conditional variance follows a GED distribution is the optimal model in modeling the bivariate time series data under study and more efficient in the forecasting process compared with the individual model and the hybrid model. This is due to having the lowest values for accuracy measures. Different software packages (MATLAB (2018a), SAS 9.1, R 3.5.2 and EViews 9) were used to analyze the data under consideration.

Crossref
View Publication Preview PDF
Quick Preview PDF
Publication Date
Sat Apr 01 2023
Journal Name
Baghdad Science Journal
Honeyword Generation Using a Proposed Discrete Salp Swarm Algorithm
...Show More Authors

Honeywords are fake passwords that serve as an accompaniment to the real password, which is called a “sugarword.” The honeyword system is an effective password cracking detection system designed to easily detect password cracking in order to improve the security of hashed passwords. For every user, the password file of the honeyword system will have one real hashed password accompanied by numerous fake hashed passwords. If an intruder steals the password file from the system and successfully cracks the passwords while attempting to log in to users’ accounts, the honeyword system will detect this attempt through the honeychecker. A honeychecker is an auxiliary server that distinguishes the real password from the fake passwords and t

... Show More
View Publication Preview PDF
Scopus (3)
Crossref (2)
Scopus Crossref
Publication Date
Thu Oct 31 2024
Journal Name
Sabrao Journal Of Breeding And Genetics
THE ROLE OF NANOTECHNOLOGY IN CROP IMPROVEMENT – A REVIEW
...Show More Authors

View Publication Preview PDF
Scopus Clarivate Crossref
Publication Date
Tue Dec 01 2009
Journal Name
Iraqi Journal Of Physics
Spectrophotometrically Analysis of PMMA as a low – Doses Dosimeter
...Show More Authors

Polymethylmethacrylate film (PMMA) of thickness 75 μm was evaluated Spectrophotometrically for using it as a low-doses gamma radiation dosimeter. The doses were examined in the range 0.1 mrad-10 krad. Within an absorption band of 200-400 nm, the irradiated films showed an increase in the absorption intensity with increasing the absorbed doses. Calibration curves for the changes in the absorption differences were obtained at 218, 301, and 343 nm. At 218 nm the response for the absorbed doses is a linear in the range 10 mrad- 10 krad. Hence it is recommended to be adopted as an environmental low doses dosimeter

View Publication Preview PDF
Publication Date
Mon Mar 11 2019
Journal Name
Baghdad Science Journal
Results on a Pre-T_2 Space and Pre-Stability
...Show More Authors

This paper contains an equivalent statements of a pre-  space, where  are considered subsets of with the product topology. An equivalence relation between the preclosed set  and a pre-  space, and a relation between a pre-  space and the preclosed set  with some conditions on a function  are found. In addition, we have proved that the graph  of  is preclosed in if  is a pre-  space, where the equivalence relation  on  is open.

     On the other hand, we introduce the definition of a pre-stable ( pre-stable) set by depending on the concept of a pre-neighborhood, where we get that every stable set is pre-stable. Moreover, we obtain that

... Show More
View Publication Preview PDF
Scopus (4)
Scopus Crossref
Publication Date
Sun Nov 01 2020
Journal Name
Iraqi Journal For Electrical And Electronic Engineering
A Systematic Review of Brain-Computer Interface Based EEG
...Show More Authors

The futuristic age requires progress in handwork or even sub-machine dependency and Brain-Computer Interface (BCI) provides the necessary BCI procession. As the article suggests, it is a pathway between the signals created by a human brain thinking and the computer, which can translate the signal transmitted into action. BCI-processed brain activity is typically measured using EEG. Throughout this article, further intend to provide an available and up-to-date review of EEG-based BCI, concentrating on its technical aspects. In specific, we present several essential neuroscience backgrounds that describe well how to build an EEG-based BCI, including evaluating which signal processing, software, and hardware techniques to use. Individu

... Show More
View Publication
Crossref (8)
Crossref
Publication Date
Mon Apr 08 2019
Journal Name
International Journal Of Building Pathology And Adaptation
A scientometric analysis of BIM studies in facilities management
...Show More Authors
Purpose

The purpose of this paper is to statistically classify and categorize Building Information Modelling (BIM)-Facility Management (FM) publications in order to extract useful information related to the adoption and use of BIM in FM.

Design/methodology/approach

This study employs a quantitative approach using science mapping techniques to examine BIM-FM publications using Web of Science (WOS) database for the period between 2000 and April 2018.

Findings

The findi

... Show More
View Publication
Scopus (36)
Crossref (32)
Scopus Clarivate Crossref
Publication Date
Fri Jan 01 2021
Journal Name
Cogent Engineering
Content-based image retrieval: A review of recent trends
...Show More Authors

View Publication
Scopus (109)
Crossref (98)
Scopus Clarivate Crossref
Publication Date
Sat Apr 24 2021
Journal Name
Turkish Journal Of Computer And Mathematics Education (turcomat)
A Linguistic Study of Epitaphs in Selected English Texts
...Show More Authors

This research aims at analysing epitaphs written by Thomas Moore for the memory of Rupert Southey, the epitaph is analysed linguistically and stylistically on four levels graphology, phonology, morphology, and lexico-syntax level to explore the elements that the writer uses the most at each level. Bearing in mind Nowottny approach (1962) (to text analysis) who believes that the linguistic analysis of a literary text is not just a marginal but a necessity” (Bakuuro etal., 2018:34). The researcher has selected and analysed a written epitaph of famous individual associated with English, literature. The study involves both literary and linguistic analysis, with much more concentration through the analysis on the aspect of linguistics. In fact

... Show More
View Publication Preview PDF
Publication Date
Tue Apr 30 2024
Journal Name
Iraqi Journal Of Science
Credit Card Fraud Detection Challenges and Solutions: A Review
...Show More Authors

     Credit card fraud has become an increasing problem due to the growing reliance on electronic payment systems and technological advances that have improved fraud techniques. Numerous financial institutions are looking for the best ways to leverage technological advancements to provide better services to their end users, and researchers used various protection methods to provide security and privacy for credit cards. Therefore, it is necessary to identify the challenges and the proposed solutions to address them.  This review provides an overview of the most recent research on the detection of fraudulent credit card transactions to protect those transactions from tampering or improper use, which includes imbalance classes, c

... Show More
Scopus (10)
Crossref (9)
Scopus Crossref
Publication Date
Fri Mar 23 2018
Journal Name
Entropy
Methods and Challenges in Shot Boundary Detection: A Review
...Show More Authors

View Publication
Scopus (63)
Crossref (56)
Scopus Clarivate Crossref