نشریه دفاع هوافضایی
سال سوم شماره 2 (پیاپی 10، تابستان 1403)

In this article, the process of changing a turbofan engine to an engine for use in marine transportation is investigated. From the production power of the modified engine, it is possible to supply the propulsion power and power needed by boats and ships. In the first stage, the turbofan engine is simulated, and after validation with the original model, the fan is removed from the turbofan engine. The changes caused by removing the fan are studied on the engine components and then by applying the new conditions, the output power of the engine derived from the engine is calculated. In the following, with the installation of the flow guide vane, new conditions prevail over the downstream components of the engine. In this case, by applying the new conditions, the engine output power is evaluated along with other quantities. According to the obtained results, after removing the fan from the turbofan engine, the efficiency of the compressor decreases, but with the installation of the flow guide vane, this loss is compensated and the output power of the engine is increased. Also, the effect of increasing the inlet temperature to the engine is studied in two cases without the flow guide vane and after its installation. Based on the results obtained in this part, the flow guide vane increases the production power and reduces the specific fuel consumption in different modes.

Tetracyclines are a group of antibiotics widely known for their use in treating bacterial infections in both animals and humans. Therefore, accurate and rapid measurement of tetracycline levels is crucial for ensuring the safety of materials. This laboratory study presents an electrochemical aptasensor method for measuring tetracycline, which is based on the formation of a nucleic acid aptamer complex for detecting tetracycline on the electrode surface. This aptamer structure enhances sensitivity and accuracy in tetracycline measurement and it is prepared using cyclic voltammetry and square wave electrochemical techniques. The developed aptasensor in this study can potentially be used for detecting tetracycline in pharmaceutical preparations, contaminated food products, and drinking water. In addition to medical and food applications, this optosensor can be used as a potential tool for identifying chemical and biological agents in defense and military environments. The concentrations of tetracycline used in this experiment range from 10 µM to 10 mM, and they are analyzed using CV, impedance, and DPV graphs within a voltage range of -0.6 V to 0.6 V, a scan rate of 20 mV/s, a step potential of 2 mV, and a current range of 1.6 × 10⁻⁶ to 0 A. The results indicate significant improvement in detection limits and linear range. Additionally, this sensor features high sensitivity, stability, and reusability. This study presents significant improvements in tetracycline measurement and provides high efficiency in various applications of the drug.

One of the most important concerns after the imposed war is to clear the land of mines and unexploded bombs buried in it, which unfortunately kills or injures some of our dear compatriots every year. The most important method for processing and interpreting buried magnetic anomalies is Euler's method, which estimates the depth. In this research, at first magnetic fiber data from 16 spherical models and two cylindrical models are simultaneously processed and interpreted. After that, we study ground magnetic data related to the site of the Institute of Geophysics, University of Tehran buried in the area for a study of a number of steel sheets, a hollow iron pipe and a barrage. In order to estimate the depth and boundary of the buried anomalies, the Euler method is used to construct data. The main advantage of using this technique is that it enables us to estimate the horizontal position and depth of the subsurface mass without knowing the parameters of the Earth's magnetometer.

In this research, a numerical investigation of the steady flow around an air-to-surface missile has been done using Fluent and Missile Datcom software at different speeds and angles of attack. Force and moment coefficients and contours of Mach number, pressure and temperature around the missile have been investigated. In order to reduce the numerical error of the grid, the flow in the critical aerothermal conditions is examined around the nose of the missile using a structured mesh. The results show that the missile has static stability at all speeds and a vortical flow is formed on the body and control surfaces, and with the increase of the angle of attack, these vortices become larger and cover more areas of the body and control surfaces. Examining the temperature distribution on the surface of the missile showed that the point of maximum temperature is located at the tip of the missile and at the leading edge of the control surfaces, and with the increase of the angle of attack, this point inclines towards the bottom of the missile tip. Also, with the increase of Mach number, the temperature value at this point increases. The temperature distribution on the surface of the missile in steady conditions showed that these conditions are equivalent to a very long flight of the missile with the maximum Mach number of 3.7.

Aircraft engine designers have been trying to reduce weight and increase engine efficiency for a long time. One of the passive methods to prevent flow separation, control the boundary layer, increase the pressure ratio, and reduce the weight of the turbine and compressor, is the use of tandem. Tandem improves the performance of the compressor by increasing the rotation angle of the flow and increasing the pressure ratio of the compressor. In this study, the tandem compressor geometry was extracted from the model designed at the NASA Lewis Research Center and a high-quality network was applied to it. In the present study, both rotor and stator have tandem. The software used in this study is CFX 2021, which has been analyzed with the κ-ω SST turbulence model. In this study, the difference between normal and tandem compressors was investigated and finally it was observed that the efficiency of the floor and rotor of the normal compressor is better than that of the tandem compressor. It has also been observed that the compressor stage has increased the pressure ratio by 3% at the nominal speed of the tandem, and this value is 1.5% in the rotor. Further, it was concluded that in the compressor floor, the tandem has increased the pressure ratio by 3%. Then it was concluded that the parameter of attack angle of tandem blade is higher than that of normal blade...

In this research, the design and development of Neutral Red (NHR), a commercial dye that is available with high purity, is reported as a colorimetric biosensor for the sequential identification of two amino acids, arginine (Arg) and glutathione (GSH). This method was used without the need for complex and expensive equipment and without using enzymatic methods to determine these two amino acids. With the gradual increase of arginine, the absorption spectrum of the receiver decreased at 529 nm and increased at 454 nm, and the color of the solution changed from red to yellow. Further, by adding glutathione to the neutral red-arginine (NRH-Arg) complex, an increase in absorption at 529 nm and a decrease in absorption at 454 nm were observed, and the color of the solution changed from yellow to red.In this study, the linear range for arginine and glutathione is 1.20-91.61 µmol/L and 243.11-605.49 µmol/L, respectively, and their correlation coefficient is 0.9945-0.9942, respectively. Also, the detection limit of the method is 0.61 and 25.32 µmol/L and the relative deviation for arginine at two concentrations of 0.10 and 0.50 µmol/L, respectively, and for glutathione at two concentrations of 0.370 and 0.98% and 1.17% respectively. 0.564 µmol/L was obtained, 1.20% and 1.08%, respectively. Finally, this method successfully identified and measured arginine in the blood serum samples of military barracks soldiers..