Accurate calculation of transient overvoltages and dielectric stresses from fast-front excitations is required to obtain an optimal dielectric design of power components subjected to these conditions, which are commonly due to switching and lightning, as well as utilization of power-electronic devices. Toroidal transformers are generally used at the low voltage level. However, recent investigations and developments have explored their use at the medium voltage level. This paper analyzes the model-based improvement of the insulation design of medium voltage toroidal transformers. Lumped and distributed parameter models are used and compared to predict the transient response and dielectric stress along the transformer winding. The parameters

Background: Oral diseases persist to be a major health problem all over the world. Various bacteria and fungi are found to be the possible pathogensresponsible for the oral diseases. Moringa oleifera it is an extraordinary nutritious vegetable tree with many different uses. These leaves have high medicinal value. In the present study, antibacterial and antifungal activities of aqueous extracts of plant Moringa oleifera in comparison to chlorohexidene gluconate and deionized water were determined. Materials and methods: The leaves of plant of Moringa oleifera were collected from College of Pharmacy; Baghdad, Iraq. Tested microorganism (bacterial and fungal) was isolated from different clinical specimens. In-vitroantimicrobial activity was pe

The paper presents research results of the vibration transmitted from the steering wheel of the
tractor with a 2-wheel drive to the driver’s hands. The vibration measurements were carried out on the
tractor randomly chosen from the collage of agriculture / university of Baghdad. Before testing the
tractor was examined and adjusted following the producer’s recommendations. The vibration levels
were measured during the operation tillage at idling and at full load .The field was 3١٫٧ m above level
sea. Soil was treated at soil constant moisture (1٧-20 %) with depth of plowing (١٧ cm). During
operation the weather temperature was measured (15 C) and humidity was ( 27 % ) The vibration level
on the steering whee

Kurdistan power system is expanded along years ago. The electrical power is transmitted through long transmission lines. The main problem of transmission lines is active and reactive power losses. It is important to solve this issue, unless, the most of electrical energy will lost over transmission system. In this study, High Voltage Direct Current links/bipolar connection were connected in a power system to reduce the power losses. The 132kV, 50 Hz, 36 buses Kurdistan power system is used as a study case. The load flow analysis was implemented by using ETAP.16 program in which Newton-Raphson method for three cases. The results show that the losses are reduced after inserted HVDC links.

Biotreatment using immobilized cells (IC) technology has proved to be the most promising and most economical approach for the removal of many toxic organic pollutants found in petroleum-refinery wastewater (PRW) such as phenol. This study was undertaken to evaluate the degradation of phenol by Pseudomonas cells individually immobilized in two different bio-carrier matrices including polyvinyl alcohol-guar gum (PVA-GG) and polyvinyl alcohol-agar agar (PVA-AA). Results of batch experiments revealed that complete removal of phenol was attained in the first cycle after 150 min using immobilized cells (IC) in both PVA-GG and PVA-AA. Additional cycles were confirmed to evaluate the validity of recycling beads of immob

This study investigates the implementation of Taguchi design in the estimation of minimum corrosion rate of mild-steel in cooling tower that uses saline solution of different concentration. The experiments were set on the basis of Taguchi’s L16 orthogonal array. The runs were carried out under different condition such as inlet concentration of saline solution, temperature, and flowrate. The Signal-to- Noise ratio and ANOVA analysis were used to define the impact of cooling tower working conditions on the corrosion rate. A regression had been modelled and optimized to identify the optimum level for the working parameters that had been founded to be 13%NaCl, 35ᴼC, and 1 l/min. Also a confirmation run to establish the p

Background: Plaque retention during fixed orthodontic therapy is an important cause of developing enamel demineralization. The purpose of this study was to evaluate the effect of different brackets types on the count of Streptococcus Mutans in orthodontic patients using conventional fluoridated toothpaste. Materials and Methods: Plaque samples were collected from maxillary 1st premolar teeth of twenty right handed patients (using split mouth technique) before bonding, after 48 hrs of bonding using tooth brush only, and after 2 weeks of using fluoridated toothpaste. Stainless steel bracket was bonded on right first premolar while the left one was bonded with sapphire bracket. The calculation of the Streptococcus Mutans count was done usin