The response of the combustor’s liner to the air-flow that passes through it is the key reason for the combustion chambers noise, hence the instabilities of those chambers that decreases the mechanical efficiency of such sections, by increased its mechanical vibrations, which increases the failure rate created during originating of the cracks spreading by the shakes producing by the series of high-level frequencies. Accordingly, any work debating the impact of the context of liners in the combustion chamber can provide grasping for the combustion noise generated by the undesirable vibrations, and benefits the industrial firms to design an ideal production procedure which increases the lifespan of the combustor. The goal of this work is to examine the influence of the acoustic treatment using a double layers cylindrical perforated liner on the acoustic transmission loss of gas turbines. The liners layout influences on this acoustic parameter was examined using an experimental data gained by the insertion of a full scale single and double patterns of perforated liners into the unique large scale acoustic wind tunnel at the acoustic research center at Hull University. The experimental tests under-designed acoustic signals were established firstly using 0m/s air cross-flow velocity, then by changed velocities with interval 5m/s ranging between 10m/s to 25m/s. MATLAB script was used to simulate, analyze, and figure out the data collected the insertion of single and double layer patterns of the perforated liner. The experiments demonstrated that, if the perforation acoustic treatments are applied, the acoustic transmission loss will decrease, particularly obvious at higher level frequencies. Further, the results exposed that the air tunnel with the insertion of the liner with double layers reveals an improved perforation acoustic treatment.
Background: The bond strength of the root canal sealers to dentin seems to be a very important property for maintaining the integrity and the seal of root canal filling. The aim of this study was to evaluate the shear bond strength of four different obturation systems using push-out test. Materials and methods: Forty straight palatal roots of the maxillary first molars teeth were used in this study, these roots were instrumented using crown down technique and ProTaper system, instrumentation were done with copious irrigation of 2.5% sodium hypochlorite and 17% buffered solution of EDTA was used as final irrigant followed by distilled water, roots were randomly divided into four groups according to the obturation system (ten teeth for each g
... Show MoreIn this review of literature, the light will be concentrated on the local drugs delivery systems for treating the periodontal diseases. Principles, types, advantages and indications of each type will be discussed in this paper.
This paper presents a newly developed method with new algorithms to find the numerical solution of nth-order state-space equations (SSE) of linear continuous-time control system by using block method. The algorithms have been written in Matlab language. The state-space equation is the modern representation to the analysis of continuous-time system. It was treated numerically to the single-input-single-output (SISO) systems as well as multiple-input-multiple-output (MIMO) systems by using fourth-order-six-steps block method. We show that it is possible to find the output values of the state-space method using block method. Comparison between the numerical and exact results has been given for some numerical examples for solving different type
... Show MoreBack ground: In the present study Pinealoctomy
was used to study the sympathetic innervations of
the pineal gland by the superior cervical ganglion
(SCG) of the albino rat.
Objective: Following Pinealoctomy, it is
expected to observe the Chromatolysis reaction in
some neurons of the SCG if they were to innervate
the pineal gland (i.e. retrograde Chromatolysis
changes).
Methods: Fifty albino rats were used in this study,
Pinealoctomy was done, then after a different time
interval ganglionectomy was done, in order to
study the Chromatolysis in their cell body.
Result: The present study has demonstrated that
the most obvious Chromatolysis reaction in the
neurons which innervate the pineal gland a
The study dosage ethanol in the total content of acid sialic TC and acid sialic associated fat (LBSA) in blood serum and congener brain Dkor Jerd eggs study included dosage 20 animals of male rat Ald ethanol daily for a period of four weeks and concentrations 20% and 30%, 40%, 50% and size of dose 5mlThe results of the study showed that levels of TSA homogeneous in the brain and blood serum significantly reduced Ankhvaza
This work introduces the synthesis and the characterization of N-doped TiO2 and Co3O4 thin films prepared via DC reactive magnetron sputtering technique. N-doped TiO2 thin films was deposited on indium-tin oxide (ITO) conducting substrate at different nitrogen ratios, then the Co3O4 thin film was deposited onto the N-doped TiO2 layer to synthesize a double-layer TiO2-N/Co3O4 Photoelectrochromic device. Several techniques were used to characterize the produces which are x-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy and UV–Vis spectroscopy. The Photoelectrochromic device was characterized by UV–Vis spectroscopy and the results show that the double-layer N-dope
... Show MoreThe study of the subject of (Egyptian public opinion on the Libyan revolution) came to reveal the role of Egyptian public opinion in mobilizing and solidarity for the masses. With the events witnessed by the Arab countries before the revolution, this was evident by the people 's attitudes towards the tripartite aggression against Egypt in 1956, and the June 1967 war, and the most recent what the Egyptian people showed towards the Libyan revolution. The Egyptian press followed the completion of the arms deal with France and revealed the ability of the Libyan negotiator to achieve moral gain, supported by Egyptian support to thwart the United States intentions to arm "Israel" similarly. The Egyptian people expressed a love for peace and su
... Show Moreto study the discribrion and the pollution in the environment in the south of baghdad samples of waste water from industrail units using the mercury in its process also
Smear zone is usually formed around the prefabricated vertical drains (PVD’s) due to mandrel driving. The geotechnical properties of the soil in this zone exhibit significant changes that affect the performance of the PVD’s. The most relevant property in this respect is the coefficient of permeability. So far, no serious attention is paid to investigate the effects of shearing under large shear strains on the geotechnical properties of the soft soil in Fao region. In this study, an extensive laboratory testing program was conducted to assess the characteristics of the smear zone with an emphasis on the permeability coefficient of Fao soft soil. The results show that the permeability of the smear zone is about 70% of
... Show More