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Estimation of Volumetric Mass Transfer Coefficient in Bioreactor
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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.

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Publication Date
Tue Dec 16 2008
Journal Name
Journal Of Planner And Development
Evaluation of the efficiency of the regional transport network of the district center of Mahmudiya
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The Study aims at evaluating the efficiency of the regional transportation net in Al-mahmoodiya Qadaa center. The bus station of the Qadaa center is suffering from heavy traffic jam, which is due to the ongoing movement of the adjacent provinces, particularly the small cities. They vary in the degree of their link by the regional transportation net that links the province with the centers of big cities. That affects the traffic flow of the civilians of these cities and their daily activities in hierarchical way To achieve the purpose of the study, a questionnaire has been constructed to collect data through selecting a random sample including the passengers who are coming to the bus station in Al-Mahmoodiya center to know the flo

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Publication Date
Tue Mar 19 2024
Journal Name
Baghdad Science Journal
Comparison of physical characteristics of mass and luminosity function of disk systems in barred and unbarred spiral galaxies
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إحدى أهم الطرق لتقصي توزيع المجرات عبر الزمن الكوني هي دالة اللمعان LF بدلالة كتلة القرص الباريوني ψS(Mb)، القدر . لقد درسنا تقديرًا لكثافة كتلة الباريون في عينة من المجرات الحلزونية القضيبية وغير القضيبية من الادبيات السابقة، والتي تتضمن فعليًا، لكل صنف من الاجرام السماوية ذات المحتوى الباريون المرئي، جزءًا لا يتجزأ من ناتج دالة الضيائية (LF) ونسبة الكتلة إلى الضوء. استخدمت تقنية الانحدار المتعدد لحزمة الب

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Publication Date
Tue Jun 01 2021
Journal Name
Baghdad Science Journal
Influence of Varying Temperature and Concentration on Magnetohydrodynamics Peristaltic Transport for Jeffrey Fluid with a Nanoparticles Phenomenon through a Rectangular Porous Duct
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A mathematical model constructed to study the combined effects of the concentration and the thermodiffusion on the nanoparticles of a Jeffrey fluid with a magnetic field effect the process of containing waves in a three-dimensional rectangular porous medium canal. Using the HPM to solve the nonlinear and coupled partial differential equations. Numerical results were obtained for temperature distribution, nanoparticles concentration, velocity, pressure rise, pressure gradient, friction force and stream function. Through the graphs, it was found that the velocity of fluid rises with the increase of a mean rate of volume flow and a magnetic parameter, while the velocity goes down with the increasing a Darcy number and lateral walls. Also, t

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Publication Date
Wed Jun 30 2021
Journal Name
Journal Of Economics And Administrative Sciences
Comparison of Hurst exponent estimation methods
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Through recent years many researchers have developed methods to estimate the self-similarity and long memory parameter that is best known as the Hurst parameter. In this paper, we set a comparison between nine different methods. Most of them use the deviations slope to find an estimate for the Hurst parameter like Rescaled range (R/S), Aggregate Variance (AV), and Absolute moments (AM), and some depend on filtration technique like Discrete Variations (DV), Variance versus level using wavelets (VVL) and Second-order discrete derivative using wavelets (SODDW) were the comparison set by a simulation study to find the most efficient method through MASE. The results of simulation experiments were shown that the performance of the meth

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Publication Date
Tue Jun 01 2021
Journal Name
Journal Of Economics And Administrative Sciences
Comparison of Hurst exponent estimation methods
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Publication Date
Sun Feb 28 2021
Journal Name
Journal Of Economics And Administrative Sciences
Evaluating the Efficiency of the Municipal Sector in Anbar Governorate, using the Non-Parametric Approach (DEA).
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The research aims to measure, assess and evaluate the efficiency of the directorates of Anbar Municipalities by using the Data Envelopment Analysis method (DEA). This is because the municipality sector is consider an important sector and has a direct contact with the citizen’s life. Provides essential services to citizens. The researcher used a case study method, and the sources of information collection based on data were monthly reports, the research population is represented by the Directorate of Anbar Municipalities, and the research sample consists of 7 municipalities which are different in terms of category and size of different types. The most important conclusion reached by the research i

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Publication Date
Tue Dec 06 2011
Journal Name
Journal Of Planner And Development
Human Resources Investment as an Introduction to improve the efficiency & activity of workers in E – Government
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The human resources are considered to be the main pillar of the organizations , economic development and the foundation of moving wheels of individual growth. This is considered as the basic tasks for any productive and economic activity . The investment of the human resources is the economic pillar of production , but the most important element of the production . This research tried to access the method of resource investment and to identify the problems and training as key element in establishment of E –government . A questionnaire document have been distributed to the workers at different levels in the colleges and institutes. The research concluded the necessity of job description , continuous training of the workers , usi

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Publication Date
Sun Feb 28 2021
Journal Name
Jurnal Teknologi
HEAT TRANSFER ENHANCEMENT USING PASSIVE TECHNIQUE: REVIEW
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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.

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Publication Date
Wed May 10 2023
Journal Name
Journal Of Engineering
Damage Detection and Assessment of Stiffness and Mass Matrices in Curved Simply Supported Beam Using Genetic Algorithm
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In this study, a genetic algorithm (GA) is used to detect damage in curved beam model, stiffness as well as mass matrices of the curved beam elements is formulated using Hamilton's principle. Each node of the curved beam element possesses seven degrees of freedom including the warping degree of freedom. The curved beam element had been derived based on the Kang and Yoo’s thin-walled curved beam theory. The identification of damage is formulated as an optimization problem, binary and continuous genetic algorithms
(BGA, CGA) are used to detect and locate the damage using two objective functions (change in natural frequencies, Modal Assurance Criterion MAC). The results show the objective function based on change in natural frequency i

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Publication Date
Wed Dec 31 2025
Journal Name
Journal Of Physical Education
Strength Variable Analysis With the Height of Body Mass Center In High Spike Position 4 In Volleyball League Players
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