The performance of a Mach 6 Hypersonic nozzle designed to be installed in a reflective Shock Tunnel has been experimentally investigated in this paper. The purpose of nozzle performance is to create a uniform flow at the outlet and a suitable test time considering the starting flow inside the nozzle. This nozzle is designed using modern optimization methods based on a classic converging-diverging nozzle. Also, the design and construction of a total pressure rake is presented to evaluate the flow quality in the test section. The complexity of investigating hypersonic flows is the sensitivity of the flow to the existence of various types of disturbances and also fluctuations caused by acoustic waves. Therefore, in hypersonic flow, considerations related to the design of the test section as well as the geometry of the pressure rake are very important. In this paper, the dynamics of the reflected Shock wave in the Shock tube and the starting waves in the test section are investigated. The pressure upstream of the nozzle is in good agreement with the design values with an error of 4%. The Mach number distribution is presented by measuring the pressure distribution at the end of the nozzle. Finally, the Mach number distribution at the nozzle outlet has been compared with the numerical results which shows an error about 3%. The uniformity of the flow at the end of the nozzle, which has been observed numerically and experimentally, shows the effectiveness of the optimal design method of the ultrasonic nozzle.

In the current research, an axisymmetric model is developed to study high-speed unsteady flow in the test section of a 7 meter-long Shock Tunnel. The computational calculations of the Shock Tunnel are conducted using the Fluent CFD solver. The Finite Volume Method (FVM) is used to discretize the governing equations of mass, momentum, and energy. The accuracy of the numerical model is investigated with first-order upwind, second-order upwind, and third-order MUSCL schemes. Adaptive mesh refinement is implemented to resolve the Shock wave and contact surface regions accurately. The numerical results are compared with theoretical calculations and experimental data from experimental tests and the comparison shows good agreement. Different test gases of Helium, Air and CO2, are utilized in the current study. The results show that steady test conditions are maintained for a longer test time by adjusting the pressure ratio and gas combination across the diaphragm. The highest Shock wave speed and strength are achieved for a gas combination of Helium-CO2, but a longer test duration is observed when using Air as the test gas.

In this paper, a systematic approach is considered to Design an optimal hypersonic Nozzle of a Shock Tunnel. After assigning the requirements and accomplishment of conceptual and preliminary design phases, a modern optimization strategy based on genetic algorithm and a CFD solver has been used to fine tune the nozzle convergent divergent contour. In this way, parameterization of the overall nozzle contour was done with a few control points and a Bezier curve. This arrangement showed a good flexibility to generate appropriate curves for nozzle shape. Design objectives were evaluated with a N-S viscous solver with a two equation turbulence model. Three objective functions were scalerized in a term with summation of weighted parameters: minimum total pressure loss, Mach number uniform distribution along test section and minimum axial flow deviation. A number of geometrical and physical constraints such as nozzle length, throat area, inlet and outlet diameters and inlet boundary conditions were also considered and finally, an optimized nozzle contour showed a significant improvement of about 3% in quality of the Mach 6 flow in the test section.

The flow field around a Sharp cone model configuration has been investigated by means of Schlieren facility in hypersonic Shock Tunnel. The time dependent evolution of flow around a cone of angle 11. 38° with base radius of 150mm has been visualized for a flow Mach number M = 6. 5. Experiments have been carried out with Helium as driver gas and air as test gas to visualize the hypersonic flow field. The flow establishment, steady state, and termination process of the hypersonic flow have been visualized for two different angles of attack, namely 0° &5° . Experimentally measured Shock angle compares well with the theoretical and the computational study. The measured Shock layer thickness compares well with the numerical simulation for both angles of attack.

Background: Carpal Tunnel syndrome (CTS) is the most common upper extremity impingement neuropathy caused by median nerve compression within the carpal Tunnel due to various conditions such as bone abnormalities, inflammation, trauma, neoplastic lesions and endocrinopathies. Increase in carpal Tunnel pressure of more than 20 to 30 mmHg blocks the epineural blood flow; so, the nerve function is damaged. Carpal Tunnel syndrome is primarily a clinical diagnosis supported by electrodiagnostic studies; in recent years, different imaging modalities, including magnetic resonance imaging (MRI) and ultrasound, are suggested for diagnosis of carpal Tunnel syndrome.Methods: During November 2011 and May 2013, 84 patients clinically suspicious for carpal Tunnel syndrome were enrolled in our study; the age of patients ranged from 19 to 66 with the average of 43 years and the sex ratio of women to men was 2.7: 1. All the patients underwent electerodiagnostic tests (EDT) as the gold standard diagnostic modality and the results of color Doppler sonography (CDS) were compared with electerodiagnostic findings.Findings: According to the ecterodiagnostic tests, patients with positive results of carpal Tunnel syndrome were divided into three groups of severity including mild with 9 patients (11%), moderate with 14 cases (17%) and severe with 18 patients (21%). Sensitivity of color Doppler sonography for diagnosis of carpal Tunnel syndrome was almost 83%, 71% and 55% in severe, moderate and mild groups of carpal Tunnel syndrome, respectively.Specificity of this imaging modality was determined near to 81% in all three groups of the patients.Conclusion: In addition to electerodiagnostic tests, which are considered as the modality of choice for diagnosis of carpal Tunnel syndrome, Doppler ultrasound can be a non-invasive imaging procedure for evaluation of patients that are clinically suspicious to this syndrome. Considering three groups of carpal Tunnel syndrome based on severity of electerodiagnostic signs, results of color Doppler sonography is more reliable in patients with severe signs.

Background: Median neuropathy due to nerve compression in the wrist, or carpal Tunnel syndrome (CTS), is the most common entrapment neuropathy. Incidence of CTS is high at an estimated value of 280.6 per 100, 000 patients per year. Accurate diagnosis of CTS is essential for treatment and preventing disability and morbidity.Methods: 64 patients with clinical diagnosis of CTS from the out-patient clinic of Alzahra Hospital, Isfahan, Iran were evaluated between January and March 2013. All the patients (54 women and 10 men) underwent nerve conduction study (NCS) and ultrasonography. The cross sectional area of the median nerve at the level of pisiform bone and 12cm proximal to that in elbow was estimated via ultrasonography which were used to calculate wrist/forearm ratio (WFR). The cut-off point value for WFR of median nerve was assessed and sensitivity and specificity of ultrasonography for CTS diagnosis was also determined.Findings: The optimal diagnostic cut-off values of CTS that we obtained by ROC curve was 2.07 and the areas under the ROC curve, was 0.8. This cut-off value had a sensitivity of 76%, specificity of 83%, positive predictive value (PPV) of 95% and negative predictive value (NPV) of 45%.Conclusion: The WFR is a new option in the ultra-sonographic diagnosis of CTS. This technique does not add significant time to routine ultra-sonographic examination.The use of a ratio also helps to omit the variability between populations and anatomic variation. Our initial findings suggest a high sensitivity for this method, but study of a larger population is needed for confirmation.

Background: Carpal Tunnel syndrome is a common neurological disease with various risk factors involved in its onset. The present study aimed to compare the prevalence of risk factors in two groups with and without the syndrome.Methods: In a case-control study, 100 patients with carpal Tunnel syndrome and 100 healthy people were selected and the prevalence of risk factors in carpal Tunnel syndrome were evaluated and compared between the two groups.Findings: Of the known risk factors, prevalence of working with keyboard, powerful working, repetitive movements, working with vibrating tools, inflammatory diseases, obesity, and diabetes was significantly higher in the patient group.Conclusion: Today, the risk factors in carpal Tunnel syndrome are changing, and computer users and people who work with vibrating tools are at more risk. Therefore, it is necessary to raise awareness in the community about the new disease risk factors, in order to improve the standard of industrial equipment and home appliances such as kitchen utensils as well.

Facilities built in areas affected by earthquake activity, such as Tunnels, which have always been an integral part of human life, must withstand both dynamic and static loading. It has led to the need for practical studies on the effects of earthquakes on underground structures and the factors affecting their destruction. For this purpose, in this research, at first different patterns of Tunnel’s excavation were investigated and by using Plaxis 2D software and based on Tabas earthquake in Iran, sensitivity analysis on geotechnical parameters of the soil surrounding Tunnel such as cohesion, friction angle, unit weight and modulus of elasticity was carried out, and the parameters whose changes have the greatest and least effects on the bending moment changes on the Tunnel lining are introduced. The results show that Tunnel excavation patterns significantly affect the bending moment, axial forces, displacements, and surface settlement of the Tunnel. Often, by dividing Tunnel excavation area to small parts, the values of bending moment, axial forces, displacements, and surface settlement of the Tunnel decreases in static analysis. Also, outputs of sensitivity analysis on geotechnical parameters of the soil surrounding Tunnel showed that modulus of elasticity of the soil surrounding Tunnel has the most effect and cohesion changes have the least effect on bending moment induced on Tunnel lining..

Background: Tarsal Tunnel syndrome is a relatively rare disorder .the physicians need to be cognizant of this problem in complex, vague foot complaints.Material and. Methods: Five cases with tarsal Tunnel syndrome underwent surgical decompression during a three year period (1998-2001). These cases had all failed the conservative treatment-including local steroid injection. The 4 females and one male consisted of one case of rheumatoid disease one post ankle-fracture adhesion and three cases with unknown etiology.Results: Four patients had complete relief of their symptoms and were satisfied with the, surgical outcome. One patient had some improvement, but not a full recovery from all the symptoms.Conclusion: Surgical release of compressing fibrous sheath for tarsal Tunnel syndrome is a good alternative for cases who do not respond to non-surgical treatment. The results are, however, variable and not always predictable.