Contemporary life is racing against time in its temptations and variables, and it has become shaped and changed in an amazing way in its various aspects and fields. This was facilitated by intellectual and scientific communication between civilizations, and the rapid progression in successive inventions and discoveries in the fields of science and arts of knowledge. This contributed to a great economic and commercial renaissance. Then, these economic developments entered the world into a very strong competition, which forced producers to calculate all production costs, to reach the highest profits by reducing the price of the produced commodity on the one hand, and achieving quality in appearance (especially) on the other hand. Since the machine represents an important part in the production and manufacturing process, its survival and serviceability are essential to the course of production and avoiding loss. Therefore, it was imperative for project owners to provide specialists from experts and technicians to provide the required service according to the technical rules, for the operation of those tools and devices. Thus, the maintenance contract appears as one of the necessary contemporary contracts accompanying technical and economic development. The importance of this contract and the need for its presence have increased due to a number of factors, the most prominent of which are: 1. The employer's maintenance of the machines may cost him a lot, while it would not cost him much if he entrusted its maintenance to a maintenance company. This is due to the following: A- The employer's maintenance requires him to provide an integrated work team for maintenance only. These may only be needed a few times, which is not commensurate with the amount he will pay them, especially since some of them may receive a high salary because they are rare engineers, for example. B- Maintenance may sometimes require precise machines and devices, the purchase of which may cost the employer more than if he contracted with a company that appointed itself for this purpose. 2. The increased use of machines and devices to accomplish work in this era, as they have entered most fields. Means of transportation, such as cars, planes, ships and trains, require maintenance, machines in factories require maintenance, electrical devices of all kinds require maintenance, in addition to buildings and what they in turn require in terms of maintenance. 3. Maintaining production machines preserves them and keeps them away from breakdowns as much as possible. This is because the breakdown of these machines, even for a short period, may cause large and severe losses.
In this study, the effects of blending the un-branched acrylate polymer known as Poly (n-decyl acrylate), and the branched acrylate polymer known as Poly (iso-octyl acrylate), on the viscosity index (VI), and the pour point of the Iraqi base stocks 40, and 60 respectively, were investigated. Toluene was used as a carrier solvent for both polymer types. The improvement level of oils (VI, & pour point) gained by blending the oil with the acrylate derived polymers was compared with the values of (VI, and pour point) gained by blending the oil with a commercial viscosity index, and pour point improver. The commercial lubricant additive was purchased and used by Al-Daura Refineries. It consisted of an un-known olefin copolymer dissolved i
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Background: The marginal adaptation has a key role in the success and longevity of the fixed dental restoration, which is affected by the impression and the fabrication techniques .The objective of this in vitro study was to evaluate and compare the marginal fitness of lithium disilicate crowns using two different digital impression techniques (direct and indirect techniques) and two different fabrication techniques (CAD/CAM and Press techniques). Materials and Methods: Thirty two sound upper first premolar teeth of comparable size extracted for orthodontic reason were selected in this study .Standardized preparation of all teeth samples were carried out with modified dental surveyor to receive all ceramic crown restoration with 1 mm deep
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This paper presents a comparative study of two learning algorithms for the nonlinear PID neural trajectory tracking controller for mobile robot in order to follow a pre-defined path. As simple and fast tuning technique, genetic and particle swarm optimization algorithms are used to tune the nonlinear PID neural controller's parameters to find the best velocities control actions of the right wheel and left wheel for the real mobile robot. Polywog wavelet activation function is used in the structure of the nonlinear PID neural controller. Simulation results (Matlab) and experimental work (LabVIEW) show that the proposed nonlinear PID controller with PSO
learning algorithm is more effective and robust than genetic learning algorithm; thi
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The transfer of chemical pollutants from bottled water into water due to heat, sunlight and poor storage is one of the most serious threats to human health around the world, the objective of this study was to estimate the pH value and the transport of heavy metals from plastic bottles to water, for this purpose, 30 bottles of water for 10 local brands were collected and divided into three groups, the first was left at room temperature 25°C, The second was placed in a heat oven at 25°C and the third in another oven at 50°C for two weeks. The results showed significant differences at (P<0.05) between water samples, pH value and concentrations of heavy metals (Sb, Pb, Ni, Cu, Cr, Cd and Fe) we
... Show MoreThe purpose of this paper is to investigate Religious Human Rights Violations. Religious liberty is essential for everyone, everywhere. Because religion is significant to everyone, everywhere. Humans are religious by nature. Our nature drives us to seek answers to deep questions about ultimate things. We cannot live a fully human life unless we are free to seek those answers and live according to the truths we discover. In this study, the researcher used Marsh and White model for analysis A sample of an offensive image of an Islamic concept from the book "Mohammad believes it or else." this book is a comic book written by pseudonym Abdullah Aziz and published by Crescent Moon Publishing company. The book is marked with anti- Mohammad, preju
... Show MoreIn this paper, new concepts which are called: left derivations and generalized left derivations in nearrings have been defined. Furthermore, the commutativity of the 3-prime near-ring which involves some
algebraic identities on generalized left derivation has been studied.
which is much useful in the Arabic Language generally in the Holly Quran especially. It is the pronoun I have taken in the semantic aspect from it and I have done on the surra sabba which varities the semantical pronoun in it among the pronoun of the speaker the conscience of the addressee the absent such the the siprat pronoun that comes in it with the explanation for its importance and its work and this is the subject of the first unit which I advanced it from the concept of the pronoun Linguistically and convention. After that I have lighten in some meanings which I have done in the surrat as a semantic , magnification , proud, reprimand and others which I ended my research I have reached the results from it
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