Static loads exposing to mechanical components can cause cracks, which are lead to form stress concentration regions causing the failure of structure. Generally, from 80% to 90% of structure failure is due to initiation of the cracks. Therefore, it is necessary to repair the crack and reduce its effect on the structure where the effect of the crack is modelled as an additional flexibility to the structure. In the last few years, piezoelectric materials have been considered as one of the most favourable repairing techniques. The piezoelectric material converts the applied voltage on it to a bending moment to counter the bending moment caused by the external load on the beam at the crack location. In this study, the design of the piezoelectric materials used to repair effect of crack on the mechanical behaviour of beam subjected to static loads is analytically achieved. This design includes calculating of desired dimensions of the material with the required voltage applied on it. The additional flexibility is expressed in term of a proposed unitless factor which can be calculated depend on experimental work. The results show that increasing the patch thickness increases the beam resistance to crack and load effects, while increasing the length of the piezoelectric material reduces the magnitude of the voltage required to repair the cracked beam.
The use of legislation related to electronic contracting, through the adoption of the method of enactment of legislation and legislative intervention, and to be careful and cautious in the issuance of legislative texts that do not adversely affect the business activity, which is taking its steps for the first time on the path of electronic commerce in this new world by the new knowledge of the subject theoretically and practically , With the necessary assistance of legal expertise so that legislation does not constitute barriers and obstacles to the development of electronic commerce.
This work, in fact, is an English language teaching study (henceforth, ELT) which may provide the inspiration for much –needed research on issues such as testing students' level of achievement in articulatory phonetics at the university level. It attempts to answer two questions: 1)What is college students' level of achievement in articulatory phonetics? 2- Are there any statistical significant differences in the achievement of college students in articulatory phonetics between the production and recognition testing techniques? This research falls into three sections: Section one indicates the problem, the aims, the hypotheses, the procedures, the limits and the value of the study. Section two provides a general overview of the articul
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It has become familiar to see alchemy as a methodological approach that combines conscious, diverse, psychological, social, structural, and discrete approaches in the communications technology that Marshall McLuhan found to be able to extend our bodies and senses, The media discourse has a deep and superficial structure produced by the first, with its social, cultural and historical backgrounds, in a context that connects the image with the word, as the "meanings are made" - everywhere, as described by Jonathan ) In fashion, in the arts as a whole, and from its "signs" Our analysis of «meaning», in the media, and communication through advertising, magazines, newspapers, television, and the Internet. Therefore, alchemy is preoccupied wi
... Show MoreThe Esterification kinetics of acetic acid with ethanol in the presence of sulfuric acid as a homogenous catalyst was studied with isothermal batch experiments at 50-60°C and at a different molar ratio of ethanol to acetic acid [EtOH/Ac]. Investigation of kinetics of the reaction indicated that the low of [EtOH/Ac] molar ratio is favored for esterification reaction, this is due to the reaction is catalyzed by acid. The maximum conversion, approximately 80% was obtained at 60°C for molar ratio of 10 EtOH/Ac. It was found that increasing temperature of the reaction, increases the rate constant and conversion at a certain mole ratio, that is due to the esterification is exothermic. Activity coefficients were calculated using UNIFAC progra
... Show MorePrenatal markers are commonly used in practice to screen for some foetal abnormalities. They can be biochemical or ultrasonic markers in addition to the newly used cell free Deoxyribonucleic Acid (DNA) estimation. This review aimed to illustrate the applications of the prenatal screening, and the reliability of these tests in detecting the presence of abnormal chromosomes such as trisomy-21, trisomy-18, and trisomy-13 in addition to neural tube defects. Prenatal markers can also be used in the anticipation of some obstetrical complications depending on levels of these markers in the mother’s circulation. In the developed countries, prenatal screening tests are regularly used during antenatal care period. Neural tube defects, numer
... Show MoreIn this paper we will study some of the properties of an operator by looking at the associated S-act of this operator, and conversely. We look at some operators, like one to one operators, onto operators. On the other hand, we look at some act theoretic concepts, like faithful acts, finitely generated acts, singular acts, separated acts, torsion free acts and noetherian acts. We try to determine what properties of T make the associated S-act has any of these properties.
The pioneer contributions included a sign for Iraqi Bryoflora were those of (Juratzka &
Milde) and Schiffner published at the end of the 19th century i.e. (1870 & 1897) respectively.
However, throughout the whole next century, the 20th, only few papers, by different authors,
have been published separately. They are Schiffner (1913); Handel-Mazzetti (1914); Froelich
(1959); Vondracek (1962 & 1965); Agnew &Townsend (1970); Agnew ( 1973 ) ; Agnew&
Vondracek (1975); Long (1979); Al-Ni’ma (1994). The most comprehensive work among
them was the “Moss Flora of Iraq” by Agnew & Vondracek (1975). It included a description
of 54 genera and 145 species with an identification key in addition to notes
The element carbon Carbon dioxide emissions are increasing primarily as a result of people's use of fossil fuels for electricity. Coal and oil are fossil fuels that contain carbon that plants removed from the atmosphere by photosynthesis over millions of years; and in just a few hundred years we've returned carbon to the atmosphere. The element carbon Carbon dioxide concentrations rise primarily as a result of the burning of fossil fuels and Freon for electricity. Fossil fuels such as coal, oil and gas produce carbon plants that were photosynthesized from the atmosphere over many years, since in just two centuries, carbon was returned to the atmosphere. Climate alter could be a noteworthy time variety in weather designs happening ov
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The current research aims to identify the communicative competence of university students, to identify the levels of communicative competence among university students and which of these levels are more common, and to identify the significance of differences in communicative competence among university students according to the variables of gender and specialization. The study population consisted of (782) male and female students, as the statistical analysis sample was limited to (400) male and female students to extract the psychometric properties of the current research tool. The study sample included (382) male and female students at the University of Baghdad who were chosen by the stratified random
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