The effect of internal acoustic excitation on the leading-edge, separated boundary layers and the aerodynamic performance of NACA23015 cross section airfoil are examined as a function of excitation location with ranging frequency range (50-400) Hz of the introduced acoustic. Tests are separately conducted in two sections, open type wind tunnels at the Reynolds number of 3.3x105 for measurement at angle of attack (0, 3, 6, 9 &12) deg. and 3x104 for the visualization at angle of attack (12) deg. based on the airfoil chord. Results indicated that the excitation frequency and the excitation location are the key parameters to alter the flow properties and thus to improve the aerodynamic performance. The most effective excitation frequency is found to be equal to the shear layer instability frequency and on excitation location close to the separation point. Moreover, the lift is increased and drag reduced dramatically. The corresponding boundary layers are visualized to be reattached to the surface.
Since his first existence on earth, human had formed a connecting link for a regressive, kinetic and developed relationship that comes from a semi-complicated interaction between natural environment and constructed environment, and this resulted in the survival of human and his existence continuance. Constructed environment enabled human to survive the natural environment inconstancies and enemies as predators, also it helped him to feel safe, comfortable and to practice his everyday life activities...etc. This alternative interaction resulted in creating a civilized legacy for a group of landmarks that tell about the development of this relationship by elemental output that reached us either by documents and manuscripts or as an existed
... Show MoreThe objective of this in vivo study is to investigate the effects of 337.1 nm pulsed N2 laser on cellular immune response represented by lymphocyte transformation capacity and phagocytosis activity in laboratory animals. The samples include 60 adult male BALB/c mice, were divided into control group and experimental groups. The experimental groups were divided into two main groups according to the time period after N2 laser irradiation. Each group was divided into 9 subgroups which exposed to N2 laser radiation at different values of pulse repetition rates and exposure times. The results of immunological tests demonstrated that the exposure to 180 J/cm2 of N2 laser radiation induce adverse effect to cellular immune response. The results o
... Show MoreAccurate calculation of transient overvoltages and dielectric stresses from fast-front excitations is required to obtain an optimal dielectric design of power components subjected to these conditions, which are commonly due to switching and lightning, as well as utilization of power-electronic devices. Toroidal transformers are generally used at the low voltage level. However, recent investigations and developments have explored their use at the medium voltage level. This paper analyzes the model-based improvement of the insulation design of medium voltage toroidal transformers. Lumped and distributed parameter models are used and compared to predict the transient response and dielectric stress along the transformer winding. The parameters
... Show MoreThe insulation system of a machine coil includes several layers made of materials with different characteristics. The effective insulation design of machine coils, especially in the machine end winding, depends upon an accurate model of the stress grading system. This paper proposes a modeling approach to predict the transient overvoltage, electric field, and heat generation in machine coils with a stress grading system, considering the variation of physical properties in the insulation layers. A non-uniform line model is used to divide the coil in different segments based on material properties and lengths: overhang, stress grading and slot. The cascaded connection of chain matrices is used to connect segments for the representation of the
... Show MoreThe issue of auditing contracts according to the related services is one of the important topics It has also become necessary to develop traditional procedures and auditing according to international standards to improve the profession of accounting and auditing. From this standpoint, the research aims to indicate the reflection of the contracting audit in accordance with the related services on the auditor's report. in line with the new directions regarding the need to adopt international standards in the Iraqi environment as the research problem focused on the non-comprehensiveness of the audit programs that deal with auditing contracts according to assurance commitments to contribute obtaining Governing evidence, The research
... Show MoreThe research presented the tagged (aesthetic and expressive characteristics in the works of Jean Dubuffet), so the research objective was: to know the aesthetic and expressive characteristics in the works of (Jean Dubuffet), and the research included four chapters. The aim of the research, the limits of the research, and the definition of terms. The second chapter included four topics. The first topic presented the aesthetic essence and style, while the second topic dealt with expressionism: approaches in concept and meaning.
While the third topic was preoccupied with presenting the aesthetic and expressiveness in the drawings of modernity and beyond, while the fourth topic dealt with: Jean Dubuffet and the experience of raw art. Th
The importance of our research is that it examines the causes and sources of the security challenges in the internal security environment of the GCC countries, and aims to address the most important issues that are of great interest, namely, the issue of inter-GCC differences and addressing the issues of regional security for the Gulf region, After it is one of the most dynamic and more polarized areas for the emergence of threats and challenges because of the multiplicity of sources of threat and their complexity due to the specificity of the strategic environment and the negative repercussions it can have on the Gulf region, especially the issue of regional security of the Gulf Cooperation Council Which has become a magnet for competing i
... Show MoreThis research explains to us the role of the Islamic religion in the issue of accuracy in speech and work, and how it is closely related to human production in his life, and Islam affirms that his idea is mainly reflected in his production, and how it affects the perception of the meaning of creativity. Therefore, our Islam affirmed the accuracy in every word or work we do to build a society in which people enjoy high quality in ethics and dedication in their work so that the Islamic system depends on humanity to preserve our rights on the other hand the research discusses the deliberate default and how it reflects on our production and how it makes it less good.
This research deals with the phenomenon of a similar voice phenomenon has founded
its own laws similar and includes the following phenomenon:
Azahrh aledgam: and Qdbent Tarifaoshrooth or dinaces and reflects the correlation
between language and reading and then apply the provision in sura blessed.
Phenomenon Alaalal and substitution, Two of the important acoustic phenomenon the
linguistic heritage has shown Alaalal types and the difference between him and the
substitution then counted their applications in Sura.
Similar phenomena: in name and deed shares bult causes and probability voices and
sound that refrais where tilt.
Change the morphological characteristics with the change of the factors affecting it has been shown that the Tigris River has the characteristics of the morphology of the low values in terms of depth, width and perimeter wet and gradient which in turn affected the morphological and other characteristics in terms of the direction and pattern of runoff came through the study of 48 cross-section is taken of the Tigris River Year 2008 by section for each 1 km, it has been shown that the average width of the Tigris River does not exceed 221.1 meters and the average depth of 3.9 meters either wet ocean amounted to 268.9 meters and changed the cross-section area of the last section at a rate of 4594.3 square meters, and through the study turned
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