Iranian Journal of Mechanical Engineering Transactions of ISME
Volume:24 Issue: 2, Sept 2023

In this research, the thermal conductivity and viscosity of nanofluids has been investigated. So, the best response for the highest thermal conductivity and the lowest viscosity, respectively have been checked. For this purpose, the effect of simultaneous use of CuO/Deionized Water nanofluids to evaluate the thermal conductivity and dynamic viscosity is investigated and analyzed. The focus of the work is to investigate the influence of different transport phenomena parameters by using CuO nanoparticles dispersed in Deionized water. Given that the signal-to-noise ratio has calculated from the Larger–the better relationship, therefore, it has be concluded that the thermal conductivity of nanofluid is higher at higher volume fractions and temperatures. Finally, in this condition, volume fraction of 0.4% and temperature of 40°C will be more suitable. On the other hand, Because of the signal-to-noise ratio has calculated from the smaller-the better relationship, therefore, it has be concluded that the dynamic viscosity of nanofluid is lower at lower volume fractions and higher temperature. And also, the volume fraction of 0.1% and the temperature of 33.3°C will be more suitable.

Since the outbreak of Covid-19 in (2019), the number of people suffering from respiratory diseases has not only internationally increased sharply but also the situation for other patients altered severely; therefore, the demand for inexpensive, portable, and utile ventilation medical devices with a high production rate increased and this need must have been met apace especially in less developed and deprived areas. This fact accordingly concerned academics which led to numerous design concepts with different mechanisms. By hiring a multiple criteria decision-making procedure (TOPSIS); we were able to choose the mechanism which meets requirements of our preference criteria. A dual rack and pinion mechanism provided the possibility of mechanical Ambu-bag based ventilation at any specified rate, and a 2-D look-up table-based control algorithm was applied to this work-developed system which takes the advantage of DC motor’s rotational encoder elimination. The calibration procedure and test results are also brought into detail.

This paper introduces piezoelectric excitation as a balancing mechanism for mode-localized mass micro-sensors. To this end, adopting the Hamilton principle together with the Ritz method, the non-linear reduced equations of motion governing electrostatically coupled micro-beams with piezoelectric layers are obtained. The free vibration equations associated with the present system are also extracted by linearizing the motion equations around the previously determined static configuration of the system. Solving the free vibration equations, the eigenvalue loci of the system are then plotted. Afterward, the influence of piezoelectric excitation on the veering phenomenon is studied. The results, whose accuracy is successfully validated by those available in the literature, reveal that piezoelectric excitation can drastically affect the veering phenomenon. For instance, it is observed that the application of the electrostatic voltage of 4V can be compensated by the piezoelectric excitation of -35.4695 mV so that the veering phenomenon will occur at the same coupling voltage. Given this important observation, the possibility of employing piezoelectric excitation in designing tunable resonant mass micro-sensors that operate based on the mode-localization phenomenon suggests itself.

Investigation on snake robots for pipe inspection purposes has been the subject of various papers. In this paper, we explore a unique type of snake robot that utilizes spherical modules. Ensuring proper contact between the robot and the pipe walls is crucial for successful climbing. If the normal force is too low, the friction force will not be enough for the robot to ascend, while excessive normal force can increase energy consumption. Therefore, it's necessary to investigate the robot's ability to move on sloped surfaces to ensure its practicality. In this paper, we present a new method for adjusting the robot's behavior on different surface slopes, which has been instrumental in optimizing its locomotion on sloped surfaces. Additionally, we have tested a novel torque control method to avoid boundary condition violations with promising results. The results of simulations conducted in MATLAB and Simulink have been validated by comparing them to existing experimental data. The simulations indicate that an excessive value of parameters in the proposed method can increase the generated torque by up to 295%.

The electromagnetic waves have been used to accelerate chemical reactions in comparison of conventional reactions. In this article, a numerical method has been used to compare saline water electrolysis (EL) and saline water electromagnetic electrolysis reactor (EMER) in order to realize the effect of electromagnetic waves on electrolysis process. At the first, the effect of electromagnetic waves on the ion separation has been investigated. In the following, influence of main operating parameters such as cell potential (10-16 v), salinity (110-440 mol/m³ NaCl), electrode diameters (8-20 mm), and microwave frequency (0.3-2.4 GHz) on the ion concentrations have been investigated numerically for an up-flow axisymmetric cylinder. The ion separation in EMER process has been improved dramatically in comparison with EL process. Also, the ion separation has been enhanced linearly by increasing the cell potential and initial salinity.

This paper addresses the design and experimental evaluation of a proportional-derivative-integral (PID) controller, employing a Smith predictor, for a lever arm platform with time-delay. The primary focus is on identifying the system transfer function with time-delay, which is then utilized to predict the actual delay-free output of the system using the Smith estimator. Consequently, the PID controller parameters can be established based on the delay-free portion of the model. The performance of different versions of the proposed controller is assessed through various experiments on the lever arm platform. The results obtained demonstrate good tracking performance for the arm position when operating under the designed controller, even in the presence of a delay caused by the DC motor acting as the system actuator.

A deep neural network (DNN) has been developed to model the subgrid-scale (SGS) flux associated with a passive scalar in incompressible turbulent channel flow. To construct the training dataset for the DNN, a direct numerical simulation (DNS) was performed for a channel flow at the friction Reynolds number Re_τ=179 encompassing a passive scalar transport with Prandtl number Pr=0.71 using a pseudo-spectral in-house code. The DNS data of velocity and scalar fields was filtered to obtain the SGS scalar flux vector, q_i, filtered scalar gradient, and filtered strain-rate tensor, which were subsequently used to train the DNN, enabling it to predict q_i for large-eddy simulation. A priori evaluation of the DNN’s performance in predicting q_i revealed a close match with filtered DNS data, demonstrating correlations of up to 98%, 79% and 85% for the three components of q_i. Additionally, analysis of the mean SGS dissipation and its probability density function indicated promising predictions by the DNN. Notably, this study extends the applications of DNNs for predicting q_i to the case of turbulent channel flow.