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A review of ultra-high temperature materials for thermal protection system
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Abstract<p>Ultra-High Temperature Materials (UHTMs) are at the base of entire aerospace industry; these high stable materials at temperatures exceeding 1600 °C are used to manage the heat shielding to protect vehicles and probes during the hypersonic flight through reentry trajectory against aerodynamic heating and reducing plasma surface interaction. Those materials are also recognized as Thermal Protection System Materials (TPSMs). The structural materials used during the high-temperature oxidizing environment are mainly limited to SiC, oxide ceramics, and composites. In addition to that, silicon-based ceramic has a maximum-use at 1700 °C approximately; as it is an active oxidation process over low temperature and water vapor environment condition. However, a great emphasis is required for developing structural materials in oxidation and rapid heating environment where the temperature is greater than 1700 °C. This review covers briefly all main types of Thermal Protection Systems (TPSs) and all the materials are used to fabricate them with the maximum operational temperatures. Also, it covers the promised UHTMs (SiC, ZrB<sub>2</sub>, HfB<sub>2</sub>, SiB<sub>6</sub> and B<sub>4</sub>C) which are currently using for several aerospace applications, especially for TPS. Besides, it discusses the oxidation of SiC, B<sub>4</sub>C, SiB<sub>6</sub>, ZrB<sub>2</sub> and HfB<sub>2</sub>. Therefore, the carbides and borides of the transition metals, Zr and Hf have a high-melting temperature and good stability in forming high-melting temperature oxides.</p>
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Publication Date
Mon Sep 30 2019
Journal Name
College Of Islamic Sciences
Show fate to the people of Badr By Ibrahim ibn Hasan al-Kurani (1025-1101 AH): Study, investigate and comment
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It is the grace of God and his grace that he accepts repentance for his slaves, forgives their bad deeds in return for their misfortune, or offers them a good deed, but pardons many of them for free. Therefore, it is not long for God Almighty to forgive His mercy for many of His slaves and bring them to Paradise with no punishment or punishment, even if they have committed some sins, because of the multitude of their favorable navigational disadvantages, or even without gratitude thanks to him and him. With all this, some have overlooked the old and new on these things and amazed at the hadeeth ((God may have seen the people of the full moon and said do what you want, I have forgiven you)). Therefore, the scholars tried to answer some of

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Publication Date
Fri Jan 01 2010
Journal Name
Diala, Journal
Synthesis and characterization of ( L- proline ) amino acid with (Mn+2 , Fe+2 , Co+2 , Zn+2 and Cd+2 )
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Publication Date
Tue Jan 30 2024
Journal Name
International Journal Of Engineering Pedagogy (ijep)
The Impact of Two Proposed Strategies Based on Active Learning on Students' Achievement at the Computer and Their Social Intelligence
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Active learning is a teaching method that involves students actively participating in activities, exercises, and projects within a rich and diverse educational environment. The teacher plays a role in encouraging students to take responsibility for their own education under their scientific and pedagogical supervision and motivates them to achieve ambitious educational goals that focus on developing an integrated personality for today’s students and tomorrow’s leaders. It is important to understand the impact of two proposed strategies based on active learning on the academic performance of first-class intermediate students in computer subjects and their social intelligence. The research sample was intentionally selected, consis

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Publication Date
Wed Aug 17 2022
Journal Name
Al–bahith Al–a'alami
Digital addiction and its Relationship to social isolation among children in the autism Spectrum frome the viewpoint of their parents
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 This study titled “digital addiction and its relationship to social isolation among children in the autism spectrum from the point of view of their parents” in which the
researcher addressed an important topic which is knowledge of digital addiction in a
child with autism spectrum and its relationship to social isolation in them.
The study aimed to dhed the light on the digital addiction in a spectrum child Autism
from the point of view of their parents، by knowing the extent of addiction of children
in the autism spectrum، and identifying the relationship between electronic addiction and the social isolation of children in the autism spectrum.The study presented
several hypotheses،

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Publication Date
Fri Apr 16 2021
Journal Name
Turkish Journal Of Computer And Mathematics Education (turcomat)
The Impact Of Reflexive Learning Strategy On Mathematics Achievement By First Intermediate Class Students And Their Attitudes Towards E-Learning
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Publication Date
Mon Feb 01 2016
Journal Name
Journal Of Engineering
Dust Effect on the Efficiency of Silicon Mono Crystalline Solar Modules at Different Tilt Angles at Al-Jadryia Climate Conditions
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Solar energy usage in Iraq is facing many issues; one of those is the accumulation “of the dust on the surface of the solar module which” would highly lower its efficiency. The present work study the effect of dust accumulation” on installing fixed solar modules with different inclined angles 15o, 33o, 45o, 60o. Evaluation of the solar modules performance under different circumstance conditions such as rain, wind and humidity are considered in study of dust effect on solar module performance. The results show that the lowest output average efficiencies of solar modules occurs at 15o horizontally inclined angle are 7.4% , 6.7% , 8.0% , 8.1%, and 8.4% for the cor

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Publication Date
Sat Feb 01 2014
Journal Name
Journal Of Economics And Administrative Sciences
Application Effect of the Conflict Management Strategies On Increasing Workers Productivity at the Electricity Company (IGEC) (Field Study Irbid Governorate)
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Research aimed to explore the Application Effect of the Conflict Management Strategies by the managements to solve conflict between and inside the conflicted parties within (IGEC) to increase the productivity of the workers. To collect data, 110 questioners had been distributed among managers and heads of departments of all managerial levels, 102 answered questioners regained, 5 of them were disqualify for statistical analytic, only 97 were taking in consideration   for statistical analysis presenting 93% of the retained number.

SPSS Program supported with a group of statistical tools, had been used for analysis purposes such as Kronbach Alpha test to assure the validity & stability of the t

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Publication Date
Sat Apr 01 2023
Journal Name
Iop Conference Series: Earth And Environmental Science
Effect of Irrigation Systems, Bio-Fertilizers and Polymers on some Growth Characteristics and Potato Production in Desert Soils, Karbala Governorate
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Two field experiments were conducted during the spring season 2020 in Karbala governorate to study the effect of irrigation systems, irrigation intervals, biofertilizers and polymers on some characteristics of vegetative growth and potato production. The results showed that there were significant differences in the values of the average plant height due to the effect of the double interference between the irrigation system and the improvers, The height of potato plant under any irrigation system was superior when adding conditioners compared to the control treatment, as it reached 48.56, 58.00 and 64.33cm when adding polymer, biofertilizer, and polymers+ biofertilizers, respectively compared with the control treatment of 44.64cm in the surf

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Publication Date
Tue Dec 15 2020
Journal Name
Al-academy
Formal Formation and its Semantic Projections in the Design Interior Spaces of the Daily newspapers Buildings: آراء عبد الكريم حسين
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The research deals with the topic of (formal formation and its semantic projections in the design interior spaces of daily newspapers buildings) including the research problem summarized by the following question: (does the formal formation do a semantic role in the design of the interior spaces?). The research objective has been evident in discovering strong and weak points in the formal formations and their semantic projections in the design of the interior spaces for the daily newspapers buildings, reaching at the best design foundations, and shedding light on the cognitive and scientific importance of the research, and the objective, temporal and spatial limits in addition to identifying the terms. The theoretical framework includes

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Publication Date
Wed Jan 01 2014
Journal Name
Ibn Al- Haitham J. Fo R Pure & Appl. Sci
Multiple Mixing Ratios of Gamma Rays Reaction 32 70 70 33 Ge p n As (, ) γ Using a2-ratio Method.
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The δ-mixing of γ-transitions in 70As populated in the 32 70 70 33 Ge p n As (, ) γ reaction is calculated in the present work by using the a2-ratio methods. In one work we applied this method for two cases, the first one is for pure transition and the sacend one is for non pure transition, We take into account the experimental a2-coefficient for previous works and δ -values for one transition only.The results obtained are, in general, in a good agreement within associated errors, with those reported previously , the discrepancies that occur are due to inaccuracies existing in the experimental data of the previous works.