Determining a dynamic model for an underwater robot is of great importance in design of guidance and control system. Researchers always need a complete knowledge about hydrodynamic stability derivatives coefficients of vehicle with sufficient accuracy to design a successful control system for underwater vehicles. The selection of proper Actuator in control system is important on the global performance of the system and the costs of the project. Usually, the effect of dynamic stability derivative coefficients is not considered in the design of Actuators; therefore, in the present study, it is tried to investigate the effect of these coefficients in the design of Actuators. For this purpose, firstly, the equations of motion for an underwater robot are presented. Then, hydrodynamic coefficients that contains static and dynamic coefficients are determined, using a rapid computational code and, then, the effect of hydrodynamic stability derivatives coefficients on the Operational dynamic Parameters of vehicle such as the bandwidth of the system dynamics and its role in the control system are considered. Finally, the selection of appropriate Actuator for the underwater robot and the effects of natural frequency of Actuators on the system performance are studied.

In this paper, the results of the process of analyzing potential failure situations on the Operational product of the reaction wheel condition control operator are discussed and the effects of the identified failure situations are eliminated or reduced. The technique of analyzing failure modes and their effects is the first technique in meeting the requirements of reliability in design. In this regard, the block diagram of the functional flow of the reaction wheel is presented for the first time and the dependence of the functions is presented statically in the form of a matrix. To achieve this goal, the different parts of this operation are identified and their failure modes and the cause of failures of each part are determined. Also, the effects of failure of different levels will be determined locally, at the equipment level, at the subsystem level and at the system level. In addition, the way to diagnose failure and deal with the effect of failure is presented and related analysis is performed, which is a quantitative analysis and will determine the Parameters of severity of error effect, probability number and criticality number, calculation and critical items. Then, based on the identified critical sections, a list of critical items is also extracted. The information extracted from the analysis of failure modes and their effects, while helping to improve the reliability of the design of the reaction wheel operator, will provide the designer with important data for fault and error management during the test and mission stages.

In this study, effects of dielectric barrier discharge (DBD) plasma on aerodynamic flow are investigated around NACA 0012 airfoil for plasma placement according to horizontal position close to leading edge based on 2%, 6% and 10% of the chord length with 20 mN/m plasma momentum and a Reynolds number of 106 using 2-D aerodynamic flow simulations. A user-defined function (UDF) source code is developed for application of plasma discharge in this work. Obtained results show that application of plasma Actuator results in delay of stall from 15 degree to 18 degree angle of attack (AOA) and aerodynamic efficiency toward higher AOAs (from 8 degree to 10 degree); where plasma placement close to separation region (according to 10% of chord length) has more aerodynamic efficiency compared to smaller AOAs. However, aerodynamic efficiency of 10% placement plasma is decreasing compared to plasma placement closer to leading edge for operation of higher than 10 degrees AOAs. In addition, positive capability of plasma Actuator is investigated for wide range of Reynolds number, where plasma Actuator results in improvement of aerodynamic efficiency equal to 16%, 18.9% and 70.2% in optimal AOA for Reynolds number of 105, 106 and 107

Background: A hand-held portable direct-reading monitor, including photoionization detector (PID) is renowned for its good sensitivity, considerable dynamic range, and nondestructive vapor detection ability in comparison to the tardy response of the PID in gas chromatography (GC), which its application has been restricted. In this study, the performance of a PID system (MultiRAE Lite) was evaluated as a replacement of GC in the measurement of toluene in a dynamic adsorption system. Methods: The test was done at different relative humidity levels (30%, 50%, and 80%), temperatures (21, 30, 40 ° C), and toluene concentrations (20, 100, 200, and 400 ppm). Results: The PID achieved 48% of all measurements meeting the comparison criterion. The results showed that the performance of the PID could be altered by the variables. The best performance of the PID was at temperature of 21 ° C, the relative humidity of 50%, and concentration of 200 ppm with the percentage of readings achieving the criterion of comparison to 58%, 54%, and 52%, respectively. The averages of the PID readings (mean ± SD at 200 ppm= 207. 9 ± 8. 7) were higher than the reference method measurements averages (mean ± SD at 200 ppm= 203. 5 ± 5. 8). The regression analysis of the toluene results from the PID and the reference method results indicated that the measurements were significantly correlated (r 2 = 0. 93). Conclusion: According to the results, the device response is linear. Therefore, the findings are acceptable in adsorption studies. In this way, the measurement of the sample concentration should be performed using the same instrument before and after the reactor in order to calculate the adsorption efficiency.

In this work, the effect of flow rate change, temperature, and fluid type are considered on meter factor in turbine meter with the aid of Computational Fluid Dynamics (CFD) simulation. Continuity and momentum equations along with the proper boundary conditions are numerically solved in a steady finite volume frame. SIMPLE algorithm is used for coupling the velocity and pressure field. For the simulation of turbulent flow, the RNG k-e, and for discretizing the advection scheme the second order upwind are used. The drag and lift force on turbine impellers, and the meter factor utilizing angular momentum balances are gained. The results show that the accuracy increases with temperature enhancement and is almost constant with augmenting flow rate. Moreover, the shift from heavy oil to light oil causes the measurement accuracy to increase.

A microbial-based biosensor for BOD determination of industrial and municipal wastewaters was designed and optimized. Operating conditions during measurement of BOD samples have a great impact on the sensor. So, selection of the most suitable values for operating conditions and Parameters affecting the BOD biosensor performance for accessing a highly accurate measurement is necessary. A Clark cell was used as the transducer and activated sludge collected from water and wastewater treatment plant of Shahinshahr, Iran, pretreated and used as the biological receptor. The effects of the volume of sludge immobilized on the sensor, pH of carrier fluid, flow rate of carrier fluid and volume of sample injection on the biosensor performance were studied. The optimum values for volume of sludge immobilized on the sensor, pH and flow rate of carrier fluid, and volume of sample injection were obtained equal to 500 ml, 7, 0.9 ml/min and 3 ml, respectively.

Cyanides uptake is one of the priorities of the wastewater treatment plants of the industry, because of its high toxicity and harmful effects on the environment. There are numerous physical and chemical methods for Cyanide removal, some of which are not cost-effective or create some hazardous side products. Thereby, utilizing the bio-removal processes as the cheap and bio-friendly method are taken into consideration. The Cyanide bio-removal proved to be the most effective method which possesses the possible removal pathways with the well-known enzymes. The present research aimed to investigate the Cyanids bio-removal pathways and to illustrate the most affecting Operational Parameters on this process. The information expressed in this article might be useful for some chemical engineers who work in industrial wastewater treatment facilities to assess the optimum operating conditions for Cyanids bio-uptake.