The ratio of draft tube to reactor diameters is of decisive importance for the operation behavior of air lift loop reactors. The influence of draft tube geometry was investigated with respect to oxygen mass transfer and mixing time. The diameter ratio was varied between 0.33 and 0.80. The measurements were performed in two loop reactors with liquid capacities of 11.775 and 26.49 liters using aqueous with solutions of different coalescence behavior. The results show that there is no single diameter ratio which would produce most favorable conditions for the two process parameters. With respect to the more important requirements of aerobic cultures, i.e high oxygen mass transfer and efficient mixing, a diameter ratio between 0.5 and 0.6 is recommended. If high liquid velocities in the draft tube are required a ratio of 0.6 should be used.
Background: the placement of orthodontic appliances creates a favorable environment for the accumulation of microbiota, therefore this study is to assess
the relationship between removable orthodontic appliance and oral microflora.
Materials and methods: a sample 45 patients who come to orthodontic department at the collage of dentistry/Baghdad university, divided into 3 groups:
group 1 (15) without appliance, group2 (15) with appliance for 2 weeks-2 months, and group 3 (15) with appliance for 2 -4 months, then examine the oral microflora
and compared between the 3 groups.
Results: the result showed eleven types of microorganisms appear in group 3 then followed by seven types in group 2 but only three t
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Objective: The study aims to determine the effect of Toxoplasma gondii infection on the
genetic sequence of breast cancer patients in the Medical City Hospital – Tumor Unit /
Iraq-Baghdad.
Methodology: A study was carried out in the City of Medicine / Oncology Unit / Baghdad,
during the period 1st June 2016 to 15
th March 2017. Forty samples of tissue and serum
were collected from patients who complaining from Breast cancer and infected with
Toxoplasmosis. Forty sera samples were taken from patients complaining from parasitic
infection only; without breast cancer as control group. Data is analyzed by using of
descriptive and inferential data analysis methods.
Results: The results show that there is an effe
This study aimed at recognizing the impact of empowerment of human resources strategy on enhancing the financial performance in working banks in Jordan, the axes of the strategy were: informative sharing, free and independence, working teams, and organizational power. To achieve the objective of the study, a questionnaire is designed and distributed on the sample of the study, which represented 60 employees of Banks. After analyzing the data by using SPSS, the study resulted that there is positive impact of empowerment of human resources strategy on enhancing the financial performance in working banks in Jordan. It suggested that the working banks in Jordan should establish database, and to create working teams.
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Among the different passive techniques heat pipe heat exchanger (HPHE) seems to be the most effective one for energy saving in heating ventilation and air conditioning system (HVAC). The applications for nanofluids with high conductivity are favorable to increase the thermal performance in HPHE. Even though the nanofluid has the higher heat conduction coefficient that dispels more heat theoretically but the higher concentration will make clustering .Clustering is a problem that must be solved before nanofluids can be considered for long-term practical uses. Results showed that the maximum value of relative power is 0.13 mW at nanofluid compared with other concentrations due to the low density of nanofluid at this concentration. For highe
... Show MoreAsphalt binder is a thermoplastic material that conducts as an elastic solid at lower service temperatures or throughout fast loading rate. At a high temperature or slow rate of loading, asphalt binder conducts as a different liquid. The classical duplication generates a required to assess the mechanical properties of asphalt concrete at the anticipated service temperature to reduce the stress cracking, which happens at lower temperatures, fatigue, and the plastic deformation at higher temperatures (rutting). In this study, an achievement was made to assess the effect of temperature on the mechanical characteristics of asphalt concrete mixes. A total of 132 asphalt concrete samples were attended utilizing two asphalt cement grades (40-50) a
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Asphalt pavement properties in Iraq are highly affected by elevated summer air temperatures. One of these properties is stiffness (resilient modulus). To explain the effect of air temperatures on stiffness of asphalt concrete, it is necessary to determine the distribution of temperatures through the pavement asphalt concrete layers. In this study, the distribution of pavement temperatures at three depths (2cm,7cm, 10cm) below the pavement surface is determined by using the temperature data logger instrument. A relationship for determining pavement temperature as related to depth and air temperature has been suggested. To achieve the objective of this thesis, the prepared specimens have been tested for indirect tension in accordance with
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Porous silicon (P-Si) has been produced in this work by photoelectrochemical (PEC) etching process. The irradiation has been achieved using diode laser of (2 W) power and 810 nm wavelength. The influence of various irradiation times on the properties of P-Si material such as P-Si layer thickness, surface aspect, pore diameter and the thickness of walls between pores as well as porosity and etching rate was investigated by depending on the scanning electron micrograph (SEM) technique and gravimetric measurements.
To add more details about the effect of the axial magnetic field on the plasma profile, the breakdown voltage of air was investigated at low pressure (9-15 Pa) in the presence of axial magnetic field (0.01-0.04T). The air was ignited by a DC voltage between two plain electrodes of aluminum separated by a distance (8.5cm). The measurements showed that the discharge voltage decreases to a minimum value, then returns to increase over the minimum with increasing the magnetic field strength, at all pressures in the range. It was also observed that a maximum decrease in the discharge voltage is obtained near the minimum of Paschen curve from the right side. The decrease in the discharge voltage was caused mainly by the effect of magnetic
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A novel robust finite time disturbance observer (RFTDO) based on an independent output-finite time composite control (FTCC) scheme is proposed for an air conditioning-system temperature and humidity regulation. The variable air volume (VAV) of the system is represented by two first-order mathematical models for the temperature and humidity dynamics. In the temperature loop dynamics, a RFTDO temperature (RFTDO-T) and an FTCC temperature (FTCC-T) are designed to estimate and reject the lumped disturbances of the temperature subsystem. In the humidity loop, a robust output of the FTCC humidity (FTCC-H) and RFTDO humidity (RFTDO-H) are also designed to estimate and reject the lumped disturbances of the humidity subsystem. Based on Lyapunov theo
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This research aims to study the influence of organizational power on the achievement of entrepreneurship for business organizations. It is an analytical study of the views of a sample of managers in the Iraqi Ministry of Education. The research highlights the contribution that can be made from the knowledge of the theory of business organizations in achieving organizational success. The organizational power of the organization contributes to achieving entrepreneurship in the business environment and achieving a competitive position in the work environment. The research dealt with two variables: the first is the independent variable, the organizational power in its dimensions (Expend Power, Structural Power, Prestige Power). And t
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