Preferred Language
Articles
/
alkej-140
Estimation of Volumetric Mass Transfer Coefficient in Bioreactor
...Show More Authors

 

This study is concentrated to investigate the effects of aeration and stirring speed on the volumetric mass transfer coefficient (KLa). A dynamic technique was used in estimating KLa values in order to achieve the aim of this study.

This study was done in 10L bioreactor by using two medias:-

  1. Dionized water
  2. Xanthan solution (1 g /L)

Moreover, the research covered a comparison between the obtained values of KLa.

The Xanthan solution was used because of its higher viscosity in comparison with water. It behaves similarly to the cultivation medium when organisms are cultivated in a bioreactor. Growth of organisms in the reactor leads to a change in the viscosity of the medium which affects the mass transfer.

Two variables, the effect of air flow rate (3-20 L/min) and the effect of stirring speed (250-700rpm) on KLa value were studied. Other parameters such as temperature, liquid volume, and stirrer shape and stirrer position were held constant; the results demonstrated an increase in KLa – value and mass transfer with increasing stirrer speed. Thus at higher speed, better dispersion of the bubbles was obtained. Therefore, that increased the surface / volume ratio which increased the mass transfer area i.e. KLa value.

View Publication Preview PDF
Quick Preview PDF
Publication Date
Sun Mar 02 2008
Journal Name
Baghdad Science Journal
Study the Band Energy Structure and Absorption Coefficient for PbSe Thin Films
...Show More Authors

The PbSe alloy was prepared in evacuated quarts tubs by the method of melt quenching from element, the PbSe thin films prepared by thermal evaporation method and deposited at different substrate temperature (Ts) =R.T ,373 and 473K . The thin films that deposited at room temperature (R.T=303)K was annealed at temperature, Ta= R.T, 373 and 473K . By depended on D.C conductivity measurements calculated the density of state (DOS), The density of extended state N(Eext) increases with increasing the Ts and Ta, while the density of localized state N(Eloc) is decreased . We investigated the absorption coefficient (?) that measurement from reflection and transmission spectrum result, and the effect of Ts and Ta on it , also we calculated the tai

... Show More
View Publication Preview PDF
Crossref
Publication Date
Sun Feb 28 2021
Journal Name
Jurnal Teknologi
HEAT TRANSFER ENHANCEMENT USING PASSIVE TECHNIQUE: REVIEW
...Show More Authors

Preserving and saving energy have never been more important, thus the requirement for more effective and efficient heat exchangers has never been more important. However, in order to pave the way for the proposal of a truly efficient technique, there is a need to understand the shortcomings and strengths of various aspects of heat transfer techniques. This review aims to systematically identify these characteristics two of the most popular passive heat transfer techniques: nanofluids and helically coiled tubes. The review indicated that nanoparticles improve thermal conductivity of base fluid and that the nanoparticle size, as well as the concentrations of the nanoparticles plays a major role in the effectiveness of the nanofluids.

... Show More
View Publication
Scopus (1)
Scopus Clarivate Crossref
Publication Date
Sat Aug 01 2020
Journal Name
Key Engineering Materials
Effect of Coefficient of Variation on the Reliability of Collapse Potential's Equation Predicted by ANNs
...Show More Authors

In this paper, the Reliability Analysis with utilizing a Monte Carlo simulation (MCS) process was conducted on the equation of the collapse potential predicted by ANN to study its reliability when utilized in a situation of soil that has uncertainty in its properties. The prediction equation utilized in this study was developed previously by the authors. The probabilities of failure were then plotted against a range of uncertainties expressed in terms of coefficient of variation. As a result of reliability analysis, it was found that the collapse potential equation showed a high degree of reliability in case of uncertainty in gypseous sandy soil properties within the specified coefficient of variation (COV) for each property. When t

... Show More
View Publication
Scopus Crossref
Publication Date
Thu Apr 28 2022
Journal Name
Iraqi Journal Of Science
Effect of Excitation Energy and Mass number on Most probable exciton number
...Show More Authors

Exciton model describes the excitation of particles in pre-equilibrium region of nuclear reaction by exciton. In pre-equilibrium region there is a small probability for occurring emission and the number of excitons be the probability of the emission of it possible more is called most probable exciton number MPEN. In this paper the MPEN formula was derived for protons and neutrons separately and so MPEN formula derived with taking into account the non equidistant spacing between the energy states. The MPEN was studied with the mass number where it is noticed the MPEN increases with increasing the mass number. Also, MPEN studied for different isotopes of Al, the MPEN increases with increasing mass number of isotopes. MPEN for neutron is co

... Show More
View Publication Preview PDF
Publication Date
Sun Jan 30 2022
Journal Name
Iraqi Journal Of Science
Electromagnetic Form Factors for 7,9,11Be Isotopes with Exact Center of Mass Correction
...Show More Authors

    The shell model calculations with Cohen-Kurath (C-K) interaction were carried out to investigate form factors of elastic transverse electron scattering, and magnetic dipole-moments of odd 7,9,11Be isotopes. The effect of the exact value of center of mass correction was adopted to generate the magnetic form factors in Born approximation picture. The contribution of the higher 2p-shell configuration was included to reproduce the experimental data. A significant improvement was obtained in the present results with core-polarization (CP) effect through the effective g-factors. The occupancies percentage with respect to the valence nucleons was also calculated.

View Publication Preview PDF
Scopus (2)
Scopus Crossref
Publication Date
Sat Feb 01 2014
Journal Name
Journal Of Economics And Administrative Sciences
Evaluation the performance efficiency of the Public Manufacturing Sector in Iraq for the Period (2000-2009)
...Show More Authors

The industrial production sector has an important role in the national economy of the advanced countries as well as the developing ones to get higher levels for their economy . We in Iraq , just like most of the develpoing countries , our economy still suffers of great shortage in this active sector in spite of the repeated statements about the desire of activating the contribution of this sector in the national economy . The industrial sector in Iraq suffers in general of many problems , especially the public industrial sector (manufacturing) . These problems have been  existed because of the unnatural conditions that Iraq has passed during the previous decades especially in the political and security sides . which reflecte

... Show More
View Publication Preview PDF
Crossref
Publication Date
Fri Apr 12 2019
Journal Name
Journal Of Economics And Administrative Sciences
((Requirements for raising the efficiency and development of rail transport in Iraq according to proposed scenarios))
...Show More Authors

Abstract:

 The research concerned the study of the railway transport sector in selected countries that sought to raise the efficiency of the railway network and develop it, after realizing the importance of this vital sector, which is a link between it and the rest of the other economic sectors.

The research sought to explain the methods, methods and procedures adopted by these countries for the development of the railway sector, and to benefit from these experiments to improve the efficiency of the railway transport sector in Iraq.

The railway transport sector in Iraq suffers from the erosion of railway lines and mobile units such as locomotives, pas

... Show More
View Publication Preview PDF
Crossref
Publication Date
Wed Apr 01 2015
Journal Name
Mathematical Methods In The Applied Sciences
An inverse problem of finding the time-dependent diffusion coefficient from an integral condition
...Show More Authors

View Publication
Scopus (28)
Crossref (21)
Scopus Clarivate Crossref
Publication Date
Fri Jan 01 2021
Journal Name
Fme Transactions
FAT-based adaptive backstepping control of an electromechanical system with an unknown input coefficient
...Show More Authors

This paper is focused on orthogonal function approximation technique FAT-based adaptive backstepping control of a geared DC motor coupled with a rotational mechanical component. It is assumed that all parameters of the actuator are unknown including the torque-current constant (i.e., unknown input coefficient) and hence a control system with three motor control modes is proposed: 1) motor torque control mode, 2) motor current control mode, and 3) motor voltage control mode. The proposed control algorithm is a powerful tool to control a dynamic system with an unknown input coefficient. Each uncertain parameter/term is represented by a linear combination of weighting and orthogonal basis function vectors. Chebyshev polynomial is used

... Show More
View Publication
Scopus (6)
Crossref (7)
Scopus Clarivate Crossref
Publication Date
Sat Apr 01 2023
Journal Name
Iop Conference Series: Earth And Environmental Science
Path Coefficient Analyses for Growth and Yield Traits of Barley Under Different Seeding Rates
...Show More Authors
Abstract<p>The purpose of this experiment was to determine the relationship between the path coefficient and seed rate for four different barley cultivars (Amal, Ibaa 265, Ibaa 99, and Buhooth 244) during the 2019-2020 winter season. The experiment was carried out using a split plot design with three replications according to a randomized complete block design (RCBD). The highest positive thru effect on grain yield was found for flag leaf area and harvest index at aseeding rate of 130 kg.h<sup>-1</sup>; the highest positive direct effect on grain yield was found for flag leaf area and plant height at aseeding rate of 160 kg.h<sup>-1</sup>; and the highest positive direct effe</p> ... Show More
View Publication
Scopus (1)
Scopus Crossref