In this research, the mutual correlations between ionospheric parameters (MUF, OWF and LUF) have been suggested. The datasets of the MUF and OWF parameters have been generated using ASAPS international communication model, while the LUF parameter has been calculated using the REC533 model. The calculations have been made for the connection links between the capital Baghdad and many other locations that spread over the studied zone (Middle East region). The annual time of the years (2009 & 2014) of solar cycle 24 has been adopted to make the investigation in order to get the mutual correlation between ionospheric parameters. The test results of the annual correlation between ionospheric parameters showed that the mutual correlation between MUF & OWF is simple and can be represented by a linear regression equation, while the mutual correlations between (MUF & LUF), (OWF & LUF) can be represented by a fourth order polynomial equation (Quartic Polynomial Equation). The results of the conducted study showed that there was a good fit between ionospheric parameter values that have been generated using the suggested mutual correlation equation and the results generated from the international communication models and the international recommended criterion.
The Suggested Mutual Correlation between Ionospheric Parameters for Long Distance Radio Wave Communications
Optimum Working Frequency (OWF)
Ionospheric Parameters
Lowest Usable Frequency (LUF)
Radio Wave Propagation
Publication Date
Thu Jun 30 2011
Journal Name
Al-khwarizmi Engineering Journal
Nahrain Mobile Learning System (NMLS)
Nahrain mobile learning system
short message service
wireless application protocols
multimedia messaging service
mobile learning
personal digital assistant
wireless fidelity
general packet radio service
extensible hypertext markup language
java database connectivity
The work in this paper involves the planning, design and implementation of a mobile learning system called Nahrain Mobile Learning System (NMLS). This system provides complete teaching resources, which can be accessed by the students, instructors and administrators through the mobile phones. It presents a viable alternative to Electronic learning. It focuses on the mobility and flexibility of the learning practice, and emphasizes the interaction between the learner and learning content. System users are categorized into three categories: administrators, instructors and students. Different learning activities can be carried out throughout the system, offering necessary communication tools to allow the users to communicate with each other
... Show MorePublication Date
Tue Oct 01 2013
Journal Name
Journal Of Economics And Administrative Sciences
أثـر الأدوات الداخلية لحوكمة الشركة على رأس المال الـعـامـل وانعكاسهما علـى القيـمـة الاقتصـادية المضـافـة: دراســة تطبيقيـة علـى عينــة مـــن الشـركــات الصنــاعــيــة المـدرجــة في بورصــة عـمّــان لــلأوراق المـالـيـة
/ Corporate Governance Instrument- Net Working Capital- Economic Value Added- Weighted Average Cost of Capital- Capital Asset Pricing Model
أدوات حوكمة الشركات- صافي راس المال العامل- القيمة الاقتصادية المضافة- المتوسط الموزون لكلفة راس المال- نموذج تسعير الاصول الرأسمالية.
Abstract
Objective of this research focused on testing the impact of internal corporate governance instruments in the management of working capital and the reflection of each of them on the Firm performance. For this purpose, four main hypotheses was formulated, the first, pointed out its results to a significant effect for each of corporate major shareholders ownership and Board of Directors size on the net working capital and their association with a positive relation. The second, explained a significant effect of net working capital on the economic value added, and their link inverse relationship, while the third, explored a significant effect for each of the corporate major shareholders ownershi
... Show More
Publication Date
Fri Mar 01 2019
Journal Name
Applied Acoustics
Theoretical model of absorption coefficient of an inhomogeneous MPP absorber with multi-cavity depths
Micro-perforated panel (MPP) absorber has been known as an alternative absorber to classical porous material given its facile installation
long durability
environmental friendliness and attractive appearance. Extensive studies of MPP absorber proposing the improvement of its absorption frequency bandwidth have been published. This study presents a MPP absorber introduced with inhomogeneous perforations and with multi-cavity depths. The MPP is divided into two sub-area
where each area has different hole diameter
perforation ratio and a separated backed cavity depth. The acoustic impedance is modelled using electrical equivalent circuit and the absorption coefficient is calculated under normal-incidence of sound. It is found that the inhomogeneous MPP can have good bandwidth of absorption by designing the sub-MPP of smaller perforation ratio with large hole diameter and the one having the larger perforation ratio with smaller hole diameter. The absorption bandwidth can be conveniently controlled by adjusting the cavity depth of each sub-MPP. The results from the experimental work show good agreement with the theoretical model.
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Publication Date
Mon Apr 06 2020
Journal Name
August
INFLUENCE OF SOME FACTOR ON SOMATIC EMBRYOS INDUCTION
AND GERMINATION OF DATE PALM CV BARHI BY USING CELL
SUSPENSION CULTURE TECHNIQUE
This study was done to examine different concentrations of mercuric chloride (Hgcl2) for Explants sterilization and different
concentration of NAA) mg/L with 2iP for their effect on initiation primary callus and subsequent embryogenesis in Phoenix
dactyliferae cultivar Barhi. Leaf primordial and shoot tips were excised from 2-3 years old offshoot. The result showed that
contamination percentage decreased with an increase in concentration of Hgcl2 for two explants where in the control (0.0)%
gave highest value 75% and 62.5% of contamination for leaf primordial and shoot tip respectively while the addition (0.1)%
gave a significant decrease 37.5 and 0% for explants respectively. The Explants were inoculated onto Murashiege and Skoog
1962 (MS) medium supplemented with 2iP 3mg/L and containing 0
25
50 or 100 mg/L of NAA
the addition (50) mg/L of NAA
gave highest value 68.8% in percentage of callus initiation with significant difference from addition 0% gave lowest value
(18.8)%
as well Explants of shoot tip gave significant difference was 53.1% while leaf primordial gave 28.1%
Primary callus
was transferred to fresh MS medium containing (0
5
10 and 20) mg/L of NAA with 3mg/L 2iP
Results were recorded after 12
weeks. A highest value of embryonic callus induction percentage or fresh weight and dry weight 87.5% or 1.56g and 0.47g for
the character respectively for the treat 20 mg/L while control treatment 0.0 gave the lowest value 12.5% or 0.37g and 0.14g for
same character respectively. Inoculated 1g fresh biomass into a 250 ml Erlenmeyer flask containing 50 ml MS liquid medium
supplemented with NAA 20mg/L and agitated at 150 rpm by shaker to making suspension culture the measurements of
packed cell volume ( pcv) or fresh and dry weight taken weekly for 12 weeks
maximum values were reached in the eighth week
of PCV and fresh weight but the dry weight reached to highest value in seventh week
then the curve began to decline
gradually until it reached stability in the last two weeks. The cell suspension was Diluted to different initial cell density of 100
500
10000
50000 and 100000 cells /ml with hemocytometer. The initial cell number of (10000) cells gave significant different
of plating efficiency PE (11.6)% while (100) cells gave lowest value 1.8% of PE.
Publication Date
Sat Oct 01 2016
Journal Name
Journal Of Theoretical And Applied Information Technology
Factors affecting global virtual teams’ performance in software projects
Today the trend is to perform software development work via distributed geographical area among team
individual or even as an organization. However
due to the global market and international presence of many companies
there is a need to implement a global virtual teams. The global virtual team members are gradually engaged in globalized business environments across space
time and organizational boundaries via information and communication technologies. A global virtual team relies on communication
collaboration
and information exchange are the most important criteria in global virtual teams’ operations. The purpose of this paper is to answer two research questions. The first research question is to identify the factors affecting global virtual teams’ performance. A systematic literature review was conducted to answer the first research question. The second research question is on what the rank of the factor affecting the global virtual teams’ performance according to their level of effect on global virtual teams’ performance. Online survey was conducted within 103 developers and IT managers from eight IT companies to answer the second research question. The Statistical Package for Social Science (SPSS 22) was used to analyze the collected data. In this study
we investigated factors that affect global virtual teams’ performance
factors considered include cultural differences
language problems
time-zone differences
team size
technical problems
lack of trust
lack of sufficient training
and ICT problems. Also the findings indicated that lack of sufficient training is the highest level of effect on global virtual teams’ performance. On the other hand
team size is the lowest level of effect on global virtual teams’ performance. © 2005 - 2016 JATIT & LLS. All rights reserved.
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Publication Date
Sat Oct 01 2022
Journal Name
Environmental Advances
Stability and performance studies of emulsion liquid membrane on pesticides removal using mixture of Fe3O4Â nanoparticles and span80
The current study investigated the impact of nonionic surfactant span 80 in the existence of Fe3O4 magnetic nanoparticles on the emulsification of mixture of kerosene as petroleum based organic solvents and corn oil as a green diluent in the ratio 1:1
HCl was used as internal phase and the stability of the emulsion was carried out. The proposed Pickering emulsion liquid membrane has been exploited to investigate it is ability in the extraction of Abamectin pesticides from aqueous solution without utilizing carrier agent. Further
the effects of experimental parameters on extraction efficiency and emulsion stability such as
homogenizer speed
emulsification speed
contact time
Fe3O4-Span 80 ratios
HCL concentration
internal to membrane volume ratio (I/O) and pH of the external feed solution were carried out. The results showed that more than 99% of Abamectin could be extracted at 10 min contact time with a minimum breakage percent of 0.52% at the optimal conditions. The kinetic of the extraction were studied and the mass transfer coefficient was found to be for external phase () of 1.2
interfacial reaction rate constant () of 5.83 and the overall mass transfer coefficient () of 3.91 . The results of recyclability of the PELM revealed that the emulsion stability and extraction efficiency was nearly unchanged after three cycles.
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