In this research the effect of grain size and effect of La2O3 doping on densification rate for the initial and intermediate stages of sintering were studied .The experimental results for α – cristobilite powder are modeled using ( L2-Regression ) technique in studying the effect of grain size and La2O3 doping using three particles size (6.12, 8.92, 13.6 ) µm, with undoped initial powder and with La2O3 doping . The mathematical simulation showes that the densification rates increase as the initial particles sizes decrease and vice versa. This shows that the densification depends directly on the initial compact density which reflects the contacts area between the particles . However the densification rates in the intermediate stages were enhanced compared with that of the initial stage .This is due to completion of neck growth that facilitates the mass transport between the grains ,and also, the presence of the massive grains due to the grain growth . Al so it is show that the doping enhances the densification rates in the intermediate stage due to that , the dopants act against the grain boundaries movement causing discourage closing of porosity and encourage escaping of voids enhances the densification rates .
Abstract
The aim of this research is to identify the general level of teachers’ curriculum expectations in (geography subject as a model), as well as the significance of the difference in the level of teachers’ curriculum expectations in light of the gender variables (male, female), the years of service (10 years or less - more than 10 years), the level of attitudes of fourth-grade literary students towards geography, the level of congruence between teachers’ curriculum expectations and the attitudes of fourth-grade literary students towards geography in light of the variables, the general level of congruence and the level of congruence between teachers’ curriculum expectations and the attitudes of studen
... Show Moreimportumt educational institution as (kindergartens) need teachers which qualified ownes modalities in their education for children , as Marzanu method in a way of learning and own methods of crisis management, because the teachers that own those styles of learning ginekindergarten children knowledge and the childrenIeaving based on theMeaing and knowledge and integration of their information, And teachers that earn methods of crisis management provide for the children of the kindergarten security within the educational institution which in turn affect the growth and development of the Child and then abilities, health physical, mental, psychological …etc.., The aims of the current research have identified to recognize: 1- the dimension
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Experimental results on harmonic distortions in 13.56 MHz RF Argon glow discharge using different grounded electrodes areas and electrodes spacing are presented. The experiment is carried out at four pressure values. RF power values used are between 20 and 90 watts. The results indicate significant increase in distortions at two specific values of the cone angle enclosing the two electrodes within its geometrical volume. The computation of the cone head angle gave the symmetry discharge or asymmetry as well as when the angle is small the condition is near symmetry discharge associated with decrease in the nonlinearity.
Knowledge of literature is an integral part of learning any spoken language. Learning literature expands the learner’s ability to understand the language studied. The field of literature is wide and cannot be limited to poems. It includes the etiquettes of a language and its environment, customs, and traditions etc. The Arabic language is among the languages with a centuries old history. It has achieved remarkable record accomplishments since the pre-Islamic era through to the present. This development is clear evidence of the great importance of literature in the revival of the Arabic language through different eras. As such, in Malaysia and other non-Arabic speaking countries, literature is taught in most schools, institutions and un
... Show MoreBackground: Cerebral ventricular enlargement has been associated with many neurological disorders. Whether this enlargement is primary or secondary to these pathological conditions remains controversial. To define such enlargement, one must have measurements in normal subjects (controls).
Patients and methods: One hundred-twelve (66 male and 46 females) apparently healthy normal subjects, with age ranging between 10-69 years were subjected to C. T scans as part of routine diagnostic workup for complaint of headache or recent minor motor-vehichle accident The ratio (measured as percent) of the ventricular-cross area of the lateral ventricle The maximum width (MTW) of the third ventricle was also deter
News are considered the most press arts that supply the target audiences with daily information and events happened inside and outside society since it is formed by depending on its resources which have a deep relation with formal corporations to gain their satisfaction in order to support their authority and spreading their domination by using mass media in editing their viewpoints and achieving wide acceptance among public opinion. In the field of technological development and changing in the fields of politics, society, culture, economics etc. inside Iraqi society and democratic transition help to convert news agenda from independent variation to a fellow variation while in the past the variation of mass media was the independent one
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The global oil market is one of the most important markets in the world and occupies especially for countries consuming and producing countries, and the status of understanding of the mechanism for determining prices in the market help to stand on many factors affecting oil demand and supply of oil and geopolitical factors, climate and alternative sources of energy .. etc. factors, and that the main objective of the research is to study the causes and results left behind by the oil price shocks in the world market, and the movement of these factors be through a cycle of energy that explain the strength of competition between these factors and their effects on prices, when demand increases evolution Large image leads to significan
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The purpose of this study is to elucidate the microfacies and the biozones present in the studied rocks as well as to determine their environments or deposition. The study depends mainly on the benthonic foraminiferal assemblages identified from (27) rock thin sections made available from an outcrop at Wadi Banat Al-Hassan area in the Upper Euphrates Valley. X-Ray diffraction was also used to determine the type of carbonate minerals present in the studied rocks.
This work studied the electrical and thermal surface conductivity enhancement of polymethylmethacrylate (PMMA) clouded by double-walled carbon nanotubes (DWCNTs) and multi-walled carbon nanotube (MWCNTs) by using pulsed Nd:YAG laser. Variable input factors are considered as the laser energy (or the relevant power), pulse duration and pulse repetition rate. Results indicated that the DWCNTs increased the PMMA’s surface electrical conductivity from 10-15 S/m to 0.813×103 S/m while the MWCNTs raised it to 0.14×103 S/m. Hence, the DWCNTs achieved an increase of almost 6 times than that for the MWCNTs. Moreover, the former increased the thermal conductivity of the surface by 8 times and the later by 5 times.