This paper is dealing with an experimental study to show the influence of the geometric characteristics of the vortex generators VG son the thickness of the boundary layer (∂) and drag coefficients (C_D) of the flat plate. Vortex generators work effectively on medium and high angles of attack, since they are "hidden" under the boundary layer and practically ineffective at low angles.

            The height of VGs relative to the thickness of the boundary layer enables us to study the efficacy of VGs in delaying boundary layer separation. The distance between two VGs also has an effect on the boundary layer if we take into

Highlights the role of taxes in being a major source of funding sources internal economic and social development, and then, any decrease in tax revenue caused by tax evasion, for example, would weaken the government's ability to finance their investments and core financing private sector investment as a result of reduced ability to increase their reserves's cash banks, as well as the weakening of the effectiveness of tax evasion taxes as a tool to guide economic activity in the framework of service for development, and to achieve justice. And the statement of the reasons for and methods of evasion mandated to pay the tax due on them, whether legitimately or illegal with the statement of the proposed methods to tackle tax evasion and elim

This paper contains an equivalent statements of a pre-  space, where  are considered subsets of with the product topology. An equivalence relation between the preclosed set  and a pre-  space, and a relation between a pre-  space and the preclosed set  with some conditions on a function  are found. In addition, we have proved that the graph  of  is preclosed in if  is a pre-  space, where the equivalence relation  on  is open.

     On the other hand, we introduce the definition of a pre-stable ( pre-stable) set by depending on the concept of a pre-neighborhood, where we get that every stable set is pre-stable. Moreover, we obtain that

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With the growing use of electronic commerce has worked many companies, especially public shareholding to take advantage of them treated in the trade, so that the e-commerce part of the corporate environment, and this has made a career of accounting and auditing facing new challenges to the sophistication of the information and the rapid growth in the market for electronic commerce. And raised many questions about the ability of the audit profession to facing these challenges and how to audit operations of e-commerce and how to give confidence on websites, this sense it has become necessary keep the internal control systems of this technology and what has caused changes to the accounting system, and evolve to fit the developments that hav

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The products of composites material are very sesetive to many variables, such as manufacturing process, additive materials, …. etc. Filler or additive plays a major role to determine the formation of the properties and behavior of the composites. In this study, polyethylene terephthalate-based compounds were produced and characterized. The work is concerned to prepare samples of Polyethylene terephthalate (PET) - zinc-ferrite (ZnFe₂O₄) with different addition ratio as zinc-ferrite (1, 2, 5, 10, 15 and 20) wt% obtained from mixing the solution with a hot pressing method applied under optimum conditions. The densities of the composites for all samples were calculated. Through the work the diffusion of zinc-ferrite i

The issue, the existence of God Almighty, and the creativity of the universes including the whale, and assets and how diversified, and faith in him and his lordship and divinity, is a delicate issue, and very important and dangerous, and it occupied human thought old and new, and still occupy it until God takes the land and on it. Many complex issues of thought, behavior, and ethics have resulted in the belief of many communities in the existence of the Almighty, having ruled their minds, depicting their beliefs and distancing their thoughts about slippage and abuse. When they looked at the wonders of creatures and the minutes of the assets, they thought about the planetary and astronomical motion systems. His existence was denied by ath

The characteristic of our time is the tremendous technological progress and the wide use of the Internet. Children have had a large share of this progress.as they are becoming fond of having the technological equipment of tablets and mobile phones which become indispensable for these children cannot do without them .
Recently, the phenomenon of using mobile phones and tablets by children has become more widespread, and the society in general and parents, in particular, have ignored the reasons for their health .Despite the many advantages and benefits for children who are well trained to use these devices properly that have enhanced their cognitive and social abilities, there are many disadvantages that could harm children's growth if

The Arab economy suffers from many structural imbalances problems which are getting complicated by the appearance of the world economic variables.

This change held risky challenges for the Arab economies in the light of unsuitable regional and international conditions. Since that it has been very essential  for the Arab experts, especially those related to economy and politics, to face those new challenges or, at least, adapt with them believing that they can have both positive and negative impacts on the Arab economy.

This study has acquired its importance in the light of the critical levels the Arab economy reached out of the world economic variables, resulting in long-term