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Theoretical and Experimental Reflection Coefficients in Flexible Tubes as a Function of the Mach Number
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The standard formulation of Wave Intensity Analysis (WIA) assumes that the flow velocity (U) in the conduit is <;<; the velocity of propagation of waves (c) in the system, and Mach number, M=U/c, is negligible. However, in the large conduit arteries, U is relatively high due to ventricular contraction and c is relatively low due to the large compliance; thus M is > 0, and may not be ignored. Therefore, the aim of this study is to identify experimentally the relationship between M and the reflection coefficient in vitro. Combinations of flexible tubes, of 2 m in length with isotropic and uniform circular cross sectional area along their longitudinal axes, were used to present mother and daughter tubes to produce a range of reflection coefficients. An approximately semi-sinusoidal pulse was generated at the inlet of the mother tube using a syringe pump, first in the condition of initial velocity, U 0 =0, and when U 0 >0 with steady flow to superimpose the pulse. Pressure (P) and Velocity (U) were measured in the mother tube, wave speed was determined using the foot to foot and PU-loops methods. The theoretical reflection coefficient, R t at M=0, has been compared to the experimental reflection coefficient, R at M>0, which was determined as dP-/dP+ as calculated using WIA. The function R(M) changes significantly with the geometrical and mechanical features of the connected tubes. In our experiments, R increased significantly with small values of M. In the range of M=0-0.02, R increased by 4-36%. Therefore, we conclude that M significantly affects the magnitude of reflections.

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Publication Date
Thu Feb 08 2024
Journal Name
Engineering, Technology &amp; Applied Science Research
Mitigating Reflection Cracking in Asphalt Concrete Overlays with ECC and Geotextile
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The rehabilitation of deteriorated pavements using Asphalt Concrete (AC) overlays consistently confronts the reflection cracking challenge, where inherent cracks and joints from an existing pavement layer are mirrored in the new overlay. To address this issue, the current study evaluates the effectiveness of Engineered Cementitious Composite (ECC) and geotextile fabric as mitigation strategies. ECC, characterized by its tensile ductility, fracture resistance, and high deformation capacity, was examined in interlayer thicknesses of 7, 12, and 17 mm. Additionally, the impact of geotextile fabric positioning at the base and at 1/3 depth of the AC specimen was explored. Utilizing the Overlay Testing Machine (OTM) for evaluations, the research d

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Publication Date
Wed Feb 01 2017
Journal Name
Journal Of Economics And Administrative Sciences
The Reflection Of The Financial Reporting Of Intellectual Capital Investment Decisions
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Abstract

The intellectual capital an important variable in the equation of the success of seeking economic units to achieve a competitive advantage, since it is a real capital for economic unity it constitutes a strategic importance as the main source to achieve high profitability in the economic unit and highlights the importance of showing intellectual capital components of the main Represent of human capital and structural capital and relational capital, through effective and the prominent role played by intellectual capital within the economic unity in order to achieve a sustainable competitive advantage contribute to attracting investors with longer investment decision of the most important and difficult decisions ta

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Publication Date
Sat Jul 11 2026
Journal Name
Journal Of Babylon Center For Humanities Studies
The reflection of the Arab character in Israeli children&#39;s literature in the years 1990 - 2015
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Publication Date
Thu Dec 31 2020
Journal Name
Iraqi Journal Of Market Research And Consumer Protection
SYNTHESISAND STUDY OF THE COMPLEXES OF: N-(3,4,5-TRIMETHOXY PHENYL)-N- BENZOYL THIOUREA (TMPBT) WITH A NUMBER OF TRANSITION METALS AND THEIR INDUSTRIAL AND MEDICAL IMPORTANCE: SYNTHESISAND STUDY OF THE COMPLEXES OF: N-(3,4,5-TRIMETHOXY PHENYL)-N- BENZOYL THIOUREA (TMPBT) WITH A NUMBER OF TRANSITION METALS AND THEIR INDUSTRIAL AND MEDICAL IMPORTANCE
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This paper performance for preparation and identification of six new complexes of a number of transition metals Cr (lII), Mn (I1), Fe (l), Co (II), Ni (I1), Cu (Il) with: N - (3,4,5-Trimethoxy phenyl-N - benzoyl Thiourea (TMPBT) as a bidentet ligand. The prepared complexes have been characterized, identified on the basis of elemental analysis (C.H.N), atomic absorption, molar conductivity, molar-ratio ,pH effect study, I. Rand UV spectra studies. The complexes have the structural formula ML2X3 for Cr (III), Fe (III), and ML2X2 for Mn (II), Ni (II), and MLX2 for Co (Il) , Cu (Il).

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Publication Date
Thu Dec 21 2023
Journal Name
Mathematical Modelling Of Engineering Problems
Recovering Time-Dependent Coefficients in a Two-Dimensional Parabolic Equation Using Nonlocal Overspecified Conditions via ADE Finite Difference Schemes
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Publication Date
Tue Sep 30 2008
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
EFFECT OF TEMPERATURE ON CORROSION OF CARBON STEEL BOILER TUBES IN DILUTE SODUIM CHLORIDE SOLUTION
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The corrosion behavior of carbon steel at different Temperatures and in water containing different sodium chloride
concentrations under 3 bar pressure has been investigated using weight loss method . The carbon steel specimens were
immersed in water containing (100,400,700,1000PPM) of NaCl solution and under temperature was increased from
(90-120ºC) under pressures of 3 bar. The results of this investigation indicated that corrosion rate increased with NaCl
concentrations and Temperature.

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Publication Date
Sat Apr 01 2017
Journal Name
Journal Of Economics And Administrative Sciences
Risks That Facing Tourism And The Managing Methods In The contemporary Challenges Theoretical study
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Tourist business organizations face a challenging and the risks dynamic environment reflected its impact on the community and generate extra under pressure in the responsibilities and burdens of exceptional and affected much of factors, accidents and risks as a result of the actions and attitudes of disasters variety may exceed the geography of States border, which requires the absorption of risks facing the tourism and how to manage and deal with them scientific and reasonable grounds for the diagnosis and treatment of risk and how to reduce the aggravation and the different kinds.

As risks affecting the most important and vital to organizations as a tourist aspects of the market share and styles tourist

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Publication Date
Wed Nov 08 2023
Journal Name
Technologies And Materials For Renewable Energy, Environment, And Sustainability: Tmrees23fr
Studying the relationship between the number of unit cells and the dislocation density of a crystal through the x-ray diffraction pattern of barium oxide nanoparticles
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In this research, the X-ray diffraction pattern was used, which was obtained experimentally after preparation of barium oxide powder. A program was used to analyze the X-ray diffraction lines of barium oxide nanoparticles, and then the particle size was calculated by using the Williamson-Hall method, where it was found that the value of the particle size is 25.356 nm. Also, the dislocation density was calculated, which is equal to1.555 x1015 (lines/nm2), and the value of the unit cell number was also calculated, as it is equal to 23831.

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Publication Date
Tue Jan 01 2002
Journal Name
University Of Baghdad
theoretical study of the drift velocity of electron in sf6-n2
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Publication Date
Sun Jun 01 2025
Journal Name
Iop Conference Series: Earth And Environmental Science
The safe house as a sustainable home -the Baghdadi house as a case study
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Abstract<p>A sense of safety is the first requirement for human stability in a place such as a home. Many local studies investigated Baghdadi houses and their architectural changes, but the relationship between safety and sustainability in Baghdadi houses has not been studied, so the research problem was: What are the architectural elements that relate to the concept of a safe house as a home in Baghdad as a case study? How is it related to the sustainability?</p><p>The research aims to identify the architectural elements of the safe house in Baghdad, to work on these elements by architects to enhance the sustainability of the residential environment, and create homes t</p> ... Show More
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