Preferred Language
Articles
/
XhfRNI8BVTCNdQwCuGH1
Are Narrow Line Seyfert 1 galaxies a special class of Active Galactic Nuclei?
...Show More Authors

No. Due to their apparently extreme optical to X-ray properties, Narrow Line Seyfert 1s (NLSy1s) have been considered a special class of active galactic nuclei (AGN). Here, we summarize observational results from different groups to conclude that none of the characteristics that are typically used to define the NLSy1s as a distinct group – from the, nowadays called, Broad Line Seyfert 1s (BLSy1s) – is unique, nor ubiquitous of these particular sources, but shared by the whole Type 1 AGN. Historically, the NLSy1s have been distinguished from the BLSy1s by the narrow width of the broad Hb emission line. The upper limit on the full width at half maximum of this line is 2000kms−1 for NLSy1s, while in BLSy1s it can be of several thousands of kms−1. However, this border has been arbitrarily set and does not correspond to the change of any physical property. All observed parameters in Type 1 AGN cover continues ranges of values, which does not allow to infer the existence of two different kind of populations with FWHMHb,broad = 2000kms−1 as dividing point. We argue that the usage of this velocity limit to define samples of NLSy1s galaxies – as it is usually done in comparative studies –, together with the well known observational biases, naturally favors the selection of sources with low black hole masses and high Eddington ratios that are hosted by blue spiral galaxies. Therefore selection biases might be responsible for the reported differences between NLSy1 and BLSy1 sources.

Crossref
View Publication
Publication Date
Wed Mar 04 2015
Journal Name
Environmental Earth Sciences
Isotopic study of water resources in a semi-arid region, western Iraq
...Show More Authors

View Publication
Scopus (36)
Crossref (24)
Scopus Clarivate Crossref
Publication Date
Thu Nov 15 2018
Journal Name
Journal Of Mathematical Imaging And Vision
A New Hybrid form of Krawtchouk and Tchebichef Polynomials: Design and Application
...Show More Authors

View Publication
Scopus (33)
Crossref (28)
Scopus Clarivate Crossref
Publication Date
Tue Jan 01 2013
Journal Name
Brain Research Bulletin
A note on the probability distribution function of the surface electromyogram signal
...Show More Authors

View Publication
Scopus (83)
Crossref (87)
Scopus Clarivate Crossref
Publication Date
Thu Oct 01 2015
Journal Name
Journal Of Educational And Psychological Researches
Early marriage for the minors: a phenomenon of family violence against children
...Show More Authors

It is certain that marriage has the favor of the continuity of human kind since the Prophet Adam till now. But this important event is threatened by some justifications which lead to its delay or abandonment. In the West, sexual relations, illegal friendships, and disrespect of marriage sacredness lead to this delay. While the reasons behind the delay of marriage in the Arab world refer to high dowries, women go out to work, and the religious and scientific ignorance of the need and importance of marriage. The problem also differs according to the difference between the rural and urban regions. On one hand, we find that early marriage is a necessity in the rural regions; on the other hand, the delay of marriage is a clear and nat

... Show More
View Publication Preview PDF
Publication Date
Tue Dec 01 2015
Journal Name
Solar Energy
A review of studies on using nanofluids in flat-plate solar collectors
...Show More Authors

Continuous escalation of the cost of generating energy is preceded by the fact of scary depletion of the energy reserve of the fossil fuels and pollution of the environment as developed and developing countries burn these fuels. To meet the challenge of the impending energy crisis, renewable energy has been growing rapidly in the last decade. Among the renewable energy sources, solar energy is the most extensively available energy, has the least effect on the environment, and is very efficient in terms of energy conversion. Thus, solar energy has become one of the preferred sources of renewable energy. Flat-plate solar collectors are one of the extensively-used and well-known types of solar collectors. However, the effectiveness of the coll

... Show More
Scopus (133)
Crossref (125)
Scopus Clarivate Crossref
Publication Date
Sun Sep 01 2024
Journal Name
Green Analytical Chemistry
Green methods for determination of paracetamol in drug samples: A comparative study
...Show More Authors

View Publication
Scopus (11)
Crossref (9)
Scopus Clarivate Crossref
Publication Date
Sun Jan 01 2023
Journal Name
Corporate And Business Strategy Review
The role of learning organizations in crisis management strategy: A case study
...Show More Authors

The problem of the paper focused on the role of the learning organization in the crisis management strategy, and the extent of the actual interest in both the learning organization and the crisis management and aimed at diagnosing and analyzing that and surrounding questions. The Statistical Package for the Social Sciences (SPSS) program was used to calculate the results and the correlation coefficient between the two main variables. The methodology was descriptive and analytical. The case study was followed by a questionnaire that was distributed to a sample of 31 teachers. The paper adopted a seven-dimensional model of systemic thinking that encourages questioning, empowerment, provision of advanced technologies, and strategic lea

... Show More
View Publication
Scopus (13)
Crossref (8)
Scopus Crossref
Publication Date
Wed Nov 01 2023
Journal Name
Solar Energy
Optimizing performance of water-cooled photovoltaic-thermal modules: A 3D numerical approach
...Show More Authors

To evaluate and improve the efficiency of photovoltaic solar modules connected with linear pipes for water supply, a three-dimensional numerical simulation is created and simulated via commercial software (Ansys-Fluent). The optimization utilizes the principles of the 1st and 2nd laws of thermodynamics by employing the Response Surface Method (RSM). Various design parameters, including the coolant inlet velocity, tube diameter, panel dimensions, and solar radiation intensity, are systematically varied to investigate their impacts on energetic and exergitic efficiencies and destroyed exergy. The relationship between the design parameters and the system responses is validated through the development of a predictive model. Both single and mult

... Show More
View Publication
Scopus (22)
Crossref (24)
Scopus Clarivate Crossref
Publication Date
Fri Jan 01 2021
Journal Name
Computers, Materials & Continua
A Technical Framework for Selection of Autonomous UAV Navigation Technologies and Sensors
...Show More Authors

View Publication
Scopus (30)
Crossref (21)
Scopus Clarivate Crossref
Publication Date
Sun Jan 01 2023
Journal Name
Journal Of Engineering
The Behavior of the Al-Kadhim Minaret during Earthquakes: A Virtual Study
...Show More Authors

The study focuses on the causes of minaret tilting as well as possible solutions. The major aims of this study are to improve knowledge of historical tall structure stability and rehabilitation operations using the finite element approach to model the soil and minaret (PLAXIS 3D 2020), a platform for computational soil investigation and modeling. The numerical analysis aims to identify stresses, settlement, and deformation of the soil and minaret in various scenarios like Earthquakes, explosions, and winds. The simulation of the problem by the PLAXIS 3D revealed that the greatest lateral displacement computed at the Top Minaret is 5.5 cm, and the greatest vertical movement is calculated to be 3 cm. Seismic settlement is the effect of ear

... Show More
View Publication Preview PDF
Crossref