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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
Tue Jan 08 2019
Journal Name
International Journal Of Mechanical Engineering And Technology (ijmet)
MANUFACTURING AND ANALYSIS CUSTOM FOOT ORTHOTIC FOR FLEXIBLE FLATFOOT
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This paper presents two main parts: The first part involves manufacturing the specimens form composite material for mechanical testing (tensile, flexural and fatigue tests), then design a custom foot orthesis (CFO) and manufacturing from composite lamination (3nylglass 2carbon fiber 3nylglass) for patient suffer from flexible flat foot since birth and over-pronation. The second part of this research involves a design a model of custom foot orthesis in (solid work 2018) and then analysis of custom foot orthosis in engineering analysis program (ANSYS V.18.2).The applied pressure in boundary condition adopted from Force Sensor Resistance (FSR 402 ) in various regions in foot after wearing composite CFO. Used a composite materials in engineerin

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Publication Date
Sun Dec 01 2019
Journal Name
Journal Of Economics And Administrative Sciences
Analysis The Consistency Between The Tariff And The Exchange Rate And Their Reflection On The Trade Balance In Iraq
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       The trade balance is considered as a way to join the national economy with the world, So it is the mirror that reflect the economic center of the country and it is point to competitive ability of it, The tariff and the exchange rate perform a great role to motivate the domestic production and improve the trade balance if we direct them to achieve the same purpose. The Iraqi economic has trade balance which achieve overabundant during the years of studying because of the oil exports, while the other exports represent a small percentage it is hardly remember, and expansion in imports from other side causes exhaustion in oil revenues, and this make the trade balance in permanent

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Publication Date
Sun Mar 15 2020
Journal Name
Journal Of The College Of Education For Women
The Use of English as Lingua Franca in the Classes of UKM: as A Case of Study
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           English has for long been one of the most widely used media of communication globally, especially in the Malaysian universities. It has been termed as a Lingua Franca because it is shared with other languages which are considered first languages by different speakers. For this reason, English as a Lingua Franca (ELF) has attracted a number of researchers to investigate its variety via other languages in various communities. The objective of this paper is therefore to establish the strategies which are employing by the international students at the National University of Malaysia/ UniversitiKebangsaan Malaysia (UKM) as an example of one of the Malaysian universities; when they e

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Publication Date
Wed Jan 02 2019
Journal Name
Differential Equations And Dynamical Systems
Stability and Bifurcation in a Prey–Predator–Scavenger System with Michaelis–Menten Type of Harvesting Function
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Publication Date
Tue Mar 15 2022
Journal Name
Al-academy
Dramatic function of temporal variables in the feature film
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Time and space are indispensable basics in cinematic art. They contain the characters, their actions and the nature of events, as well as their expressive abilities to express many ideas and information. However, the process of collecting space and time in one term is space-time, and it is one of Einstein’s theoretical propositions, who sees that Time is an added dimension within the place, so the study here differs from the previous one, and this is what the researcher determined in the topic of his research, which was titled (The Dramatic Function of Space-Time Variables in the Narrative Film), Which included the following: The research problem, which crystallized in the following question: What is the dramatic function of the tempor

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Publication Date
Thu Apr 30 2020
Journal Name
Journal Of Economics And Administrative Sciences
Prediction of the number of births in the Governorate of Basra for the period (1998-2050)
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The adoption of many mathematical concepts contributes to the construction of models of sports and the population can be interpreted to explain the movement and growth of the population lead to proper planning to manage the requirements of the population and meet their needs of providing education or providing medical services, health and others. In this study, the number of births in the Governorate of Basrah for the period (1998-2050) is estimated to be based on the assumption that the population of the visually impaired is a stable society. If the rate of growth is (0.0492), some demographic indicators are important for maintaining the average age of women at pregnancy (27.817). Each woman will give birth (3.74) female birth d

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Publication Date
Sun Dec 01 2019
Journal Name
Journal Of Economics And Administrative Sciences
The extent of adopting a number of green processing chain management activities in industrial companies An analytical study behind a sample of workers in Kirkuk Cement Factory
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The research is based on the basic idea that companies today are moving towards a new trend towards protecting the environment coupled with the increasing wareness of the pollution damage caused by these companies due to their operations and activities in the environment. The two main reasons that led the researchers to choose this subject is the need to adapt the companies themselves in response to successive developments, The great development was that companies moved from the sole economic responsibility of the business to social responsibility by emphasizing socially responsible profit. The problem of research is the knowledge of the availability of the dimensions of the green processing series in Kirkuk Cement Factory The re

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Publication Date
Thu Jun 08 2023
Journal Name
Iraqi Journal Of Laser
PDF The effect of nanoelectrodes number and length on enhancing the THz photomixer performance
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Abstract: Despite the distinct features of the continuous wave (CW) Terahertz (THz) emitter using photomixing technique, it suffers from the relatively low radiation output power. Therefore, one of effective ways to improve the photomixer emitter performance was using nanodimensions electrodes inside the optical active region of the device. Due to the nanodimension sizes and good electrical conductivity of silver nanowires (Ag-NWs), they have been exploited as THz emitter electrodes. The excited surface plasmon polariton waves (SPPs) on the surface of nanowire enhances the incident excitation signal. Therefore, the photomixer based Ag-NW compared to conventional one significantly exhibits higher THz output signal. In thi

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Publication Date
Mon May 01 2017
Journal Name
Journal Of The Mechanical Behavior Of Biomedical Materials
Bioactivity, cytocompatibility and thermal properties of experimental Bioglass-reinforced composites as potential root-canal filling materials
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To evaluate the bioactivity and the cytocompatibility of experimental Bioglass-reinforced polyethylene-based root-canal filling materials. The thermal properties of the experimental materials were also evaluated using differential scanning calorimetry, while their radiopacity was assessed using a grey-scale value (GSV) aluminium step wedge and a phosphor plate digital system. Bioglass 45S5 (BAG), polyethylene and Strontium oxide (SrO) were used to create tailored composite fibres. The filler distribution within the composites was assessed using SEM, while their bioactivity was evaluated through infrared spectroscopy (FTIR) after storage in simulated body fluid (SBF). The radiopacity of the composite fibres and their thermal properties were

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Publication Date
Sun Dec 07 2014
Journal Name
Baghdad Science Journal
Oscillations of First Order Neutral Differential Equations with Positive and Negative Coefficients
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Oscillation criterion is investigated for all solutions of the first-order linear neutral differential equations with positive and negative coefficients. Some sufficient conditions are established so that every solution of eq.(1.1) oscillate. Generalizing of some results in [4] and [5] are given. Examples are given to illustrated our main results.

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