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Inducing Frictional Force to Enhance the Transient Response in Beams
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This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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Publication Date
Thu Dec 15 2022
Journal Name
Journal Of Baghdad College Of Dentistry
Force degradation of orthodontic elastomeric chains: A literature review
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Background: Elastomeric chains are used to generate force in many orthodontic procedures, but this force decays over time, which could affect tooth movement. This study aimed to study the force degradation of elastomeric chains. Data and Sources: An electronic search on Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, LILACS, and PubMed was made, only articles written in English were included, up to January 2022.Study selection: Fifty original articles, systematic reviews, and RCTs were selected. Conclusion: Tooth movement, salivary enzymes, alcohol-containing mouthwash, whitening mouthwash, and alkaline and strong acidic (pH <5.4) solutions all have a significant impact on elastomeric chain force degradation. T

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Publication Date
Sat Dec 11 2021
Journal Name
Engineering, Technology &amp; Applied Science Research
Behavior of RC Beams Strengthened with NSM-CFRP Strips Subjected to Fire Exposure: A Numerical Study
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The use of Near-Surface Mounted (NSM) Carbon-Fiber-Reinforced Polymer (CFRP) strips is an efficient technology for increasing flexural and shear strength or for repairing damaged Reinforced Concrete (RC) members. This strengthening method is a promising technology. However, the thin layer of concrete covering the NSM-CFRP strips is not adequate to resist heat effect when directly exposed to a fire or at a high temperature. There is clear evidence that the strength and stiffness of CFRPs severely deteriorate at high temperatures. Therefore, in terms of fire resistance, the NSM technique has a significant defect. Thus, it is very important to develop a set of efficient fire protection systems to overcome these disadvantages. This pape

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Publication Date
Wed Apr 25 2018
Journal Name
Earthquake And Structures
Response of circular footing on dry dense sand to impact load with different embedment depths
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Publication Date
Thu Feb 01 2018
Journal Name
Journal Of Economics And Administrative Sciences
Comparison Some Robust Estimators for Estimate parameters logistic regression model to Binary Response – using simulation)).
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 The logistic regression model of the most important regression models a non-linear which aim getting estimators have a high of efficiency, taking character more advanced in the process of statistical analysis for being a models appropriate form of Binary Data.                                                          

Among the problems that appear as a result of the use of some statistical methods I

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Publication Date
Sun Sep 07 2014
Journal Name
Baghdad Science Journal
Response of green lacewing Chrysoperla carnea (Stephens) to various densities of Ephestia cautella (walk)eggs
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Results of exposure larvae of the most important predator in the integrated pest management , the green lacewings, Chrysoperla carnea (Stephens) to various densities of fig moth Ephestia cautella eggs showed increasing in the number of consumed prey at decreasing rate of increasing prey density where curve slope consumption decreased gradually until leveling off. These specifications concurred with type II functional response that predators appear towards varied densities of its preys ,that was confirm by logistic regression between the proportion of prey eaten in relation to prey offered . Third larval instars of the predator showed attack rate (a) of 4.85. This was greater than the second larval instar (3.58). Handling time (Th) per

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Publication Date
Wed Oct 26 2022
Journal Name
Journal Of Medical Microbiology
Bacterial secretions in growth medium stimulate the mouse respiratory innate immune response
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ntroduction. Finding a safe innate immune response stimulator is one of the greatest challenges facing immunologists and vaccine manufacturers. Gap statement. The role of sterile bacterial secretions (SBSs) of Pseudomonas aeruginosa in stimulating the innate immune response was not investigated previously. Aim. The comparative effect of SBSs and bacterial cells of P. aeruginosa isolates isolated from freshwater (PAE) and infected wounds (PAC) on the respiratory tract innate immune response. Methodology. Four test mice groups were instilled intranasally (i.n.) with 106 c.f.u of PAC, 106 c.f.u of PAE, SBS of PAC, and SBS of PAE. Two control groups were given i.n. either LB broth or PBS. Time-course changes in IL-1 beta mRNA, TNF-alpha mRNA, I

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Publication Date
Sat Sep 14 2024
Journal Name
Al-rafidain Journal Of Medical Sciences ( Issn 2789-3219 )
Correlation between Serum Levels of Factor I, CD59, Interferon-gamma, and Interleukin-6 with the Response to Rituximab in Iraqi Patients with Rheumatoid Arthritis
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Background: Rituximab is a chimeric IgG1 kappa immunoglobulin that has been genetically modified to incorporate human constant region sequences together with murine light- and heavy-chain variable region sequences. People use it to treat rheumatoid arthritis and certain malignancies. Objective: The study aimed to assess the potential association between the serum levels of Factor I, CD59, interleukins (IL)-6, and interferon-gamma (IFN)-γ and the response to Rituximab treatment in Iraqi rheumatoid arthritis patients. Methods: A cross-sectional study was conducted at the rheumatology center at Baghdad Teaching Hospital. Ninety adult patients who have been diagnosed with rheumatoid arthritis and are receiving  Rituximab intravenous i

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Publication Date
Sun Apr 01 2012
Journal Name
Arpn
Effect of friction stir welding parameters (rotation and transverse) speed on the transient temperature distribution in friction stir welding of AA 7020-t53
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Three-dimensional nonlinear thermal numerical simulations are conducted for the friction stir welding (FSW) of AA 7020-T53. Three welding cases with tool (rotational and travel) speeds of 900rpm-40mm/min, 1400rpm-16mm/min and 1400rpm-40mm/in are analyzed. The objective is to study the variation of transient temperature in a friction stir welded plate of 5mm workpiece thickness. Based on the experimental records of transient temperature at several specific locations during the friction stir welding process for the AA 7020-T53, thermal numerical simulation is developed. The numerical results show that the temperature field in the FSW process is symmetrically distributed with respect to the welding line, increasing travel speed decreasing tran

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Scopus
Publication Date
Sun Sep 06 2015
Journal Name
Baghdad Science Journal
A theoretical Design of a cover for lowering the solar cells temperature and enhance their performance
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In this research, main types of optical coatings are presented which are used as covers for solar cells, these coatings are reflect the infrared (heat) from the solar cell to increase the efficiency of the cell (because the cell’s efficiency is inversely proportional to the heat), then the theoretical and mathematical description of these optical coatings are presented, and an optical design is designed to meet this objective, its optical transmittance was calculated using (MATLAB R2008a) and (Open Filters 1.0.2) programs

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Publication Date
Tue Apr 01 2003
Journal Name
Abhath Al- Yarmouk [basic Sciences And Engineering]
Methodology for selecting Nonprestressed Steel in Post- Tensioning Beams
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