<p>Photovoltaic (PV) systems are becoming increasingly popular; however, arc faults on the direct current (DC) side are becoming more widespread as a result of the effects of aging as well as the trend toward higher DC voltage levels, posing severe risk to human safety and system stability. The parallel arc faults present higher level of current as compared with the series arc faults, making it more difficult to spot the series arc. In this paper and for the aim of condition monitoring, the features of a DC series arc fault are analyzed by analysing the arc features, performing model’s simulation in PSCAD, and carrying out experimental studies. Various arc models are simulated and investigated; for low current arcs, the heuristic model is used where a set of parameters established. Moreover, the heuristic model’s simulated arc has been shown to be compatible with the experimental data. The features of arc noise in the electrode separation region and steady-arcing states with varied gap widths are investigated. It has been discovered that after an arc fault occurs, arc noise increases, notably in the frequency range below 50 kHz; where this property is useful for detecting DC series arc faults. Besides that, variations in air gap width are more sensitive to frequencies under 5 kHz.</p>
Human resources are considered as strategic fortune for being the main driver of the development wheel in the society, and the field of education and learning is one of the main pillars of this fortune for its great effect in the process of economic and social progress of individuals. I was the subject of education to the concerns of many countries, as adopted national policies . And regional support and the reduction of constraints, so came our study (education hub for human development) to identify the role of education in human development and to identify the obstacles facing the education process and the extent of its impacts negatively on the process of human development also contribute to the knowledge of school enrollment and the
... Show MoreIn the region of the north of Iraq using the method of analyzing thin section microfacies to 38 of rockyslices which were gathered from a place near Aqra city. These slides are divided into seven microfacies depending on lithologcal component and fossils.
1) Dolostone facies.
2)Recrystallized bioclastic wackestone facies.
3) Bioclastic packstone microfacies
4)Sucrosic dolomite facies.
5) Bioclastic grainstone in microfacies.
According to water energy, these facies were divided to three zone:
- a) Low energy environment.
- b) Transitional zone.
- c) High energy environment.
Giant Cell Fibroma (GCF) is a relatively rare oral mucosal lesion, so named due to the characteristic giant cells present within the fibrous stroma of the lesion, limited number of clinicopathological studies were performed in previously published literature. This study was performed to evaluate the clinicopathological features of Giant cell fibroma in a sample of Iraqi patients. Formalin-fixed paraffin-embedded sections from 22 giant cell fibroma in period between 2010 and 2018 were retrieved from the laboratory of oral pathology of Baghdad University/College of Dentistry, Clinical data and microscopic features were reviewed and analyzed according to the available surgical reports. The mean age of patients at the time of diagnosis was 29.6
... Show MoreThis research was aimed to study the pollen morphology for the genus Pterocephalus(Vaill) from Dipsacaceae family in Iraq, and to utilize these feathers in isolating the species as valuable taxonomic traits for enriching Iraqi flora. The study included characteristics of the type, shape, size, sculpturing and apertures, as well as determining the full dimensions using light microscopy as well as numerical analysis of this species and draw polygonal shapes and denderogram convergence between species. The results of the study of pollen and polygonal forms showed significant differences in the characteristics at the level of each species, which helps to identification the genus species, as it was found that the pollen was a tricolp
... Show MoreChristian rites and rituals to be performed, not abandon them, and they see it as a sacred duty in Christ's (as) followers, including: (secret baptisms among Christian denominations, descriptive study) baptisms in the Christian Mystery of God of the mysteries of the Church, every Christian must be baptized always resented It was alaimanh, the Guide mentioned in the Bible by Jesus to his disciples ((just go make disciples of all Nations and immersed them in the name of the father and of the son and of the Holy Spirit, teaching them to observe all that I advised you, and here I am with you all days to the end of the age))( And be baptized in the name of the father and the son and the Holy Spirit, and that's what makes this practice through th
... Show MoreThe researcher wanted to make an attempt to identify the foundations of social solidarity, to strengthen the bonds of brotherhood among society, and spread the causes of compassion in the hearts of its members.
The researcher has taken a short course in the hearts of the beloved to hearts.
The current research was conducted to report the synthesis of alumina powder from Iraqi kaolin. The kaolin was transformed to metakaolin by calcinations at temperature 800 °C for three hours. Then the calcined kaolin was treated with (1.5 M) from H2SO4 for 6 hours to form Al2(SO4)3.12H2O solution. The precipitate was dried at 80oC for 10 hours and calcinations at different temperatures for two hours. The samples which result was characterized by X–Ray diffraction (XRD) and X–Ray fluorescence (XRF). The results indicate to the crystalline hydrate aluminum sulfate for the sample that be as – synthesis and when calcinations at 600 oC transformed into aluminum sulfate phase. The phases of alumina which we obtain consisted of a gamma a
... Show MoreThe paradise, the collection of a paradise through which it shows us the wonders of the divine-made, and reflect us the pleasure of looking and luster of beauty, and the splendor of creation, and all this is in the interest of this human being; To be a safety valve to collapse. But if this man deviates and forgot the blessed man, drowned in the vanity and vanity, and deviated from the divine method, this same heaven will disown him and reveal to him another face of destruction and devastation.
What we will see in the folds of the search, God willing
During more than (50) years past, India has achieved considerable social and economic progress. It is also generally assumed that the future progress will be even more rapid and that India will be an important player in the global market. India has only (2.5) percent of global land whereas it has to provide home for one-sixth of world's population .On examining the past trends of India's population ,it may be observed that during the latter half of the twentieth century ,about (650) million populations were added to the country ,thus living in a country with a high population density and high growth rate , India in need a transition from high fertility high mortality to a low fertility low mortality and towards stable population situatio
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