When employing shorter (sub picosecond) laser pulses, in ablation kinetics the features appear which can no longer be described in the context of the conventional thermal model. Meanwhile, the ablation of materials with the aid of ultra-short (sub picosecond) laser pulses is applied for micromechanical processing. Physical mechanisms and theoretical models of laser ablation are discussed. Typical associated phenomena are qualitatively regarded and methods for studying them quantitatively are considered. Calculated results relevant to ablation kinetics for a number of substances are presented and compared with experimental data. Ultra-short laser ablation with two-temperature model was quantitatively investigated. A two-temperature model for the description of transition phenomena in a non-equilibrium electron gas and a lattice under picosecond laser irradiation is proposed. Some characteristics are hard to measure directly at all. That is why the analysis of physical mechanisms involved in the ablation process by ultra-short laser pulses has to be performed on the basis of a theoretical consideration of `indirect' experimental data. For Copper and Nickel metal targets, the two-temperature model calculations explain that the temperature of the electron subsystem increased suddenly and approached a peak value at the end of laser pulse. In addition, the temperature profile of lattice temperature subsystem evolution slowly, and still increasing after the end of laser pulse. A good agreement prevails when a comparison between the present results and published results.
The laminar fluid flow of water through the annulus duct was investigated numerically by ANSYS fluent version 15.0 with height (2.5, 5, 7.5) cm and constant length (L=60cm). With constant heat flux applied to the outer duct. The heat flux at the range (500,1000,1500,2000) w/m2 and Reynolds number values were ≤ 2300. The problem was 2-D investigated. Results revealed that Nusselt number decrease and the wall temperature increase with the increase of heat flux. Also, the average Nusselt number increase as Re increases. And as the height of the annulus increase, the values of the temperature and the local and average Nusselt number increase.
The mass attenuation coefficient for beta particles through pure Polyvinyl chloride (PVC) and flax fibers- reinforced PVC composite were investigated as a function of the absorber thickness and the absorber to source distance. The beta particles mass attenuation coefficients were obtained using a NaI(Tl) energy selective scintillation counter with 90Sr/ 90Y beta source having an energy range from (0.546-2.275) MeV. Pure PVC polymer samples were prepared by compacting the PVC powder in a mould at high pressure (10bar) and temperature about 140°C for 30 minutes. A hot press system was used for this process. The experimentally obtained values of mass attenuation coefficients for 90Sr and 90Y were found to be 7.72 cm2.g-1and 0.842 cm2.g-1 r
... Show MoreThe Middle Cenomanian-Early Turonian Mishrif Formation includes important carbonate reservoirs in Iraq and some other surrounding countries due to their high reservoir quality and wide geological extension. The 2D models of this study for facies, effective porosity and water saturation indicate the vertical and lateral heterogeneity of the Mishrif Formation reservoir properties in the Majnoon oil field. Construction of 2D reservoir model of the Mishrif Formation to explain the distribution of facies and petrophysical properties (effective porosity and water saturation) by using RockWorks software. The increase of effective porosity is attributed to the presence of shoal facies.The high water saturation is attributed to the existence of rest
... Show MoreScientists were interested in the statement of the concept of companions and the definition of the companion in terms of his status or his novel or inherent to the Prophet of Allah (peace be upon him) and was for those who did not walk in the translations and the abundant share in this work, and among these scientists Hafiz Shams al-Din al-Dhahabi, which was translated to the companions His books, indicating their status and effort, and who had a novel of them - what we will see in the folds of the research, God willing -
The aim of the current research is to verify the effect of the cognitive modeling strategy on the achievement of the chemistry course for the students of the first intermediate grade. To achieve the objective of the research, the null hypothesis was formulated via cognitive modeling strategy. The results showed that the experimental group's students performed better than the students in the control group. In the light of the results, the researchers concluded: The impact of the cognitive modeling strategy in the achievement of students of first intermediate grade in chemistry.
The research was titled: Approval of the Imam of the Nuclear of Iraqis through the curriculum of the students.
The research revolves around the study of the weight of the imam nuclear jurisprudence in which the views of the Iraqi jurists of the Imam Shafi'i agreed through the book of students' approach to the nuclear imam, the research included a brief translation of the nuclear imam, and the definition of his place in the Shafi'i school, and then the definition of Iraqi jurists and then study the jurisprudence The course of research is only three issues, and compared with the views of imams, and the statement of the most correct opinion, and God and the conciliator.
researcher
The aim of this study is to look at the potential of a local sustainable energy network in a pre-existing context to develop a novel design beneficial to the environment. Nowadays, the concept of smart cities is still in the developmental phase/stage andwe are currently residing in a transitional period, therefore it is very important to discover new solutions that show direct benefits the people may get from transforming their city from a traditional to a smart city. Using experience and knowledge of successful projects in various European and non-European smart cities, this study attempts to demonstrate the practical potential of gradually moving existing cities to t
... Show MoreAsphaltene is a component class that may precipitate from petroleum as a highly viscous and sticky material that is likely to cause deposition problems in a reservoir, in production well, transportation, and in process plants. It is more important to locate the asphaltene precipitation conditions (precipitation pressure and temperature) before the occurring problem of asphaltene deposition to prevent it and eliminate the burden of high treatment costs of this problem if it happens. There are different models which are used in this flow assurance problem (asphaltene precipitation and deposition problem) and these models depend on experimental testing of asphaltene properties. In this study, the used model was equation of
... Show MoreShatt Al-Hilla was considered one of the important branches of Euphrates River that supplies irrigation water to millions of dunams of planted areas. It is important to control the velocity and water level along the river to maintain the required level for easily diverting water to the branches located along the river. So, in this research, a numerical model was developed to simulate the gradually varied unsteady flow in Shatt AL-Hilla. The present study aims to solve the continuity and momentum (Saint-Venant) equations numerically to predict the hydraulic characteristics in the river using Galerkin finite element method. A computer program was designed and built using the programming language FORTRAN-77. Fifty kilometers was consid
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