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Optimal Dielectric Design of Medium Voltage Toroidal Transformer with Electrostatic Shield under Fast Front Excitation
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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 of the toroidal transformer are computed using the finite element method considering a three-dimensional geometry. Different strategies for insulation design are proposed by means of optimal insulation thickness and electrostatic shield to reduce transient overvoltage and dielectric stress. The results show that the proposed optimal insulation design based on particle swarm optimization with electrostatic shield can substantially reduce the dielectric stress and dielectric distances. Comparison between simulations and experimental results demonstrates that the frequency domain modeling approach results in accurate calculation of transient overvoltages produced by fast front excitation and can be used effectively for insulation design.

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Publication Date
Sun Sep 02 2012
Journal Name
Baghdad Science Journal
Determination of optimal conditions for laccase production by Pleurotus ostreatus using sawdust as solid medium and its use in phenol degradation
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The ability of four local fungal isolates for extracellular laccase production has been tested with five grams 1:1(w/v) humidified sawdust as substrate in mineral salt medium. After 21 day of incubation at 25±1 ? C and using one mycelial plug (5mm), higher level of laccase activity (0.15U/ml) and specific activity (15U/mg) were observed by Pleurotus ostreatus in comparison with other fungal isolates. The results of optimum conditions for laccase production from selected isolate showed that, the maximum laccase activity (0.55U/ml) and specific activity (55U/mg) were obtained at moisture ratio 1:3 (w/v), using 3 mycelial plugs (5 mm), after 15 days incubation period at 25±1 ? C. The results of phenol degradation by crud laccase revealed th

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Publication Date
Fri Jan 01 2021
Journal Name
Egyptian Journal Of Chemistry
Microstructure and Dielectric Properties of Polyaniline Doped with Copper Nanoparticles
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Polyaniline (PANI) has been prepared by the oxidation method in order to fabricate it with various concentrations of copper nanoparticles (CuNPs) which produced using the reduction method. Various techniques have characterized pure PANI and PANI doped CuNPs composites, such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS), which were provided important information about the structure and morphology of the fabricated polymer nanocomposites. The properties of dielectric permittivity (έ), dielectric loss (ἔ) and electrical conductivity (σ_AC) properties were studied at room temperature versus a range

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Publication Date
Mon Dec 07 2020
Journal Name
Egyptian Journal Of Chemistry
Microstructure and Dielectric Properties of Polyaniline Doped with Copper Nanoparticles
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Publication Date
Tue Dec 01 2020
Journal Name
Propulsion And Power Research
Heat transfer enhancement from heat sources using optimal design of combined fins heat-sinks
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Publication Date
Tue Oct 31 2023
Journal Name
College Of Islamic Sciences
The shield And its provisions in Islamic jurisprudence
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Since I live in a society in which violence has become widespread, and killing among its own people flared up till they began to kill under the excuse of taking shelter, in these pages I would like to explain the status of taking shelter in the light of Islamic Law (Sharia), exploring scholars’ opinions in the legitimacy or illegitimacy of this issue according to the legal standards.
And, to acquaint people, and myself in the first place, with the true nature and the gravity of this issue; to expose it to those who are unaware of it; to remind those who are already aware of it. I would refute the fabrications, remove the suspicions which surround it untill it made the forbidden permissible; the wrong right. I would explain to those

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Publication Date
Mon Aug 01 2022
Journal Name
Baghdad Science Journal
Performance Assessment of Solar-Transformer-Consumption System Using Neural Network Approach
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Solar energy is one of the immeasurable renewable energy in power generation for a green, clean and healthier environment. The silicon-layer solar panels absorb sun energy and converts it into electricity by off-grid inverter. Electricity is transferred either from this inverter or from transformer, consumed by consumption unit(s) available for residential or economic purposes. The artificial neural network is the foundation of artificial intelligence and solves many complex problems which are difficult by statistical methods or by humans. In view of this, the purpose of this work is to assess the performance of the Solar - Transformer - Consumption (STC) system. The system may be in complete breakdown situation due to failure of both so

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Publication Date
Mon Jan 01 2018
Journal Name
Journal Of Engineering
Optimal Economic Design of Diversion Structures during Construction of a Dam by Particle Swarm Optimization
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Publication Date
Mon Jan 01 2018
Journal Name
International Journal Of Science And Research (ijsr)
Optimal Economic Design of Diversion Structures during Construction of a Dam by Particle Swarm Optimization
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Diverting river flow during construction of a main dam involves the construction of cofferdams, and tunnels, channels or other temporary passages. Diversion channels are commonly used in wide valleys where the high flow makes tunnels or culverts uneconomic. The diversion works must form part of the overall project design since it will have a major impact on its cost, as well as on the design, construction program and overall cost of the permanent works. Construction costs contain of excavation, lining of the channel, and construction of upstream and downstream cofferdams. The optimization model was applied to obtain optimalchannel cross section, height of upstream cofferdam, and height of downstream cofferdamwith minimum construction cost

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Publication Date
Wed Dec 30 2009
Journal Name
Iraqi Journal Of Physics
Capacitance-Voltage and Current-Voltage Characteristic for Multi- Walled Carbon Nanotubes Grown in Oxygen Atmosphere
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Carbon nanotubes were prepared by an arc-discharge method,
under different values of pressure of oxygen gas. The structure of
multi-walled carbon nanotubes powders has been characterized by
low-angle X-ray diffraction .The morphology of carbon nanotube
powder was examined by transmission electron microscope. The
capacitance-voltage and current- voltage (dark and illumination
current) characterization were measured under different values of
pressure (10-3, 10-4, 10-5) mbar of oxygen gas

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Publication Date
Wed Dec 01 2010
Journal Name
Iraqi Journal Of Physics
Current–voltage and capacitance-voltage characteristics of Se/Si heterojunction prepared by DC planar magnetron sputtering technique
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In this work, the effect of annealing temperature on the electrical properties are studied of p-Se/ n-Si solar cell, which p-Se are deposit by DC planar magnetron sputtering technique on crystal silicon. The chamber was pumped down to 2×10−5 mbar before admitting the gas in. The gas was Ar. The sputtering pressure varied within the range of 4x10-1 - 8x10-2mbar by adjusting the pumping speed through the opening control of throttle valve. The electrical properties are included the C-V and I-V measurements. From C-V measurements, the Vbi are calculated while from I-V measurements, the efficiency of solar cell is calculated.

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