The standard formulation of Wave Intensity Analysis (WIA) assumes that the flow velocity (U) in the conduit is <;<; the velocity of propagation of waves (c) in the system, and Mach number, M=U/c, is negligible. However, in the large conduit arteries, U is relatively high due to ventricular contraction and c is relatively low due to the large compliance; thus M is > 0, and may not be ignored. Therefore, the aim of this study is to identify experimentally the relationship between M and the reflection coefficient in vitro. Combinations of flexible tubes, of 2 m in length with isotropic and uniform circular cross sectional area along their longitudinal axes, were used to present mother and daughter tubes to produce a range of reflection coefficients. An approximately semi-sinusoidal pulse was generated at the inlet of the mother tube using a syringe pump, first in the condition of initial velocity, U 0 =0, and when U 0 >0 with steady flow to superimpose the pulse. Pressure (P) and Velocity (U) were measured in the mother tube, wave speed was determined using the foot to foot and PU-loops methods. The theoretical reflection coefficient, R t at M=0, has been compared to the experimental reflection coefficient, R at M>0, which was determined as dP-/dP+ as calculated using WIA. The function R(M) changes significantly with the geometrical and mechanical features of the connected tubes. In our experiments, R increased significantly with small values of M. In the range of M=0-0.02, R increased by 4-36%. Therefore, we conclude that M significantly affects the magnitude of reflections.
Due to its safety, low cost, real-time nature, and widespread availability, ultrasound has been employed as a diagnostic technique for numerous intraocular disorders. Unfortunately, speckle artifact that depends on the tissue is seen in ultrasound imaging. In this study, we present a technique for lowering speckle noise and enhancing ultrasound images to enhance human diagnostic performance. This technique combines the undecimated wavelet transform (UDWT) with a wavelet coefficient mapping function, which was utilized to improve the contrast of the denoised images acquired from the first component after the noise was removed using the UDWT. This technique can be used to enhance the visual quality of medical photographs as well as to enha
... Show MoreBackground: Rheumatoid arthritis is a chronic inflammatory autoimmune disease characterized by joint inflammation, involvement of exocrine salivary and lacrimal glands may occur as extra-articular mani¬festations in this disease. This study aimed to provide evidence of altered in function and composition of salivary gland in patients with rheumatoid arthritis by determine salivary flow rate and some biochemical parameters(total protein, amylase, peroxidase) and to investigate the relationship between disease activity and changes in function and composition of salivary gland. Materials and Methods: Fifty five patients with RA (7 males and 48 females) were enrolled in this study with age range (20-69) years. The patients were separated int
... Show MoreBackground: Malignant lymphomas represent about 5% of all malignancy of the head and neck region which can involve lymph nodes as well as soft tissue and bone of the maxillofacial region. Apoptosis is considered a vital component of various processes including normal cell turnover, proper development and functioning of the immune system. Inappropriate apoptosis is a factor in many human conditions including neurodegenerative diseases, ischemic damage, autoimmune disorders and many types of cancer. Expression of p53 Proteins in Hodgkin׳s and Non Hodgkin׳s lymphomas suggested that it can help in monitoring of patients and the markers may aid in controlling the progression of lymphoma and detect the degree of aggressiveness of the diseas
... Show MoreManipulation is a discursive concept which plays a key role in political discourse by which politicians can impose some impact on their recipients through using linguistic features, most prominent of which are personal pronouns (Van Dijk, 1995). The aim of this study is to investigate how politicians utilize the personal pronouns, namely; We and I and their possessive forms as a tool of manipulating the audience's mind based on Van Dijk's "ideological square" which shows positive-self representation and negative-other representation (Van Dijk,1998:p.69). To this end, American President Donald Trump's 2020 State of the Union speech was chosen to be the data of analysis. Only (8)
... Show MoreDecision-makers in each country work to define a list of internal and external interests, goals and threats to their countries according to the nature of their awareness of these interests, goals and threats.
Hence, Iraq is not an exception to this rule, and the process of evaluating its interests and the objectives of its foreign policy is subject to the pattern of awareness of decision-makers and the influencing forces in defining its basic interests, which often witness some kind of difference in defining them, evaluating their importance and determining the size of the threats they face. And among these interests and threats that have witnessed a difference in the assessment of their
... Show MoreDue to the energy crisis and the stringent environmental regulations, diesel engines are offering good hope for automotive vehicles. However, a lot of work is needed to reduce the diesel exhaust emissions and give the way for full utilization of the diesel fuel’s excellent characteristics.
A kind of cetane number improver has been proposed and tested to be used with diesel fuel as ameans of reducing exhaust emissions. The addition of (2-ethylhexyl nitrate) was designed to raise fuel cetane number to three stages, 50, 52 and 55 compared to the used conventional diesel fuel whose CN was 48.5. The addition of CN improver results in the decre
... Show MoreThe heat and mass transfer coefficients of the indirect contact closed circuit cooling tower, ICCCCT, were investigated experimentally. Different experiments were conducted involving the controlling parameters such as air velocity, spray water to air mass flow rate ratio, spray water flow rate, ambient air wet bulb temperature and the provided heat load to investigate their effects on the performance of the ICCCCT. Also the effect of using packing on the performance of the ICCCCT was investigated. It was noticed that these parameters affect the tower performance and the use of packing materials is a good approach to enhance the performance for different operational conditions. Correlations for mass and heat transfer coefficients are pres
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