Scientia Iranica
Volume:31 Issue: 1, Jan-Feb 2024

Laparoscopic manipulation of delicate large intra-abdominal organs is a difficult task that needs special training programs to improve the surgeons’ dexterity. In this study, the mechanical design of a robotic interface for haptic simulation of large-organ laparoscopic surgery is described. The designed robot enjoys five active DOFs, back drivability, low inertia, friction and backlash, and sufficiently large force/moment production capacity. The kinematics of the robot was analyzed and a functional prototype was fabricated for experimental tests. Results indicated that the target workspace was fully covered with no singular points inside. The mechanism was highly isotropic and the torque requirements were in the acceptable range. The trajectory tracking experiments against a 1 kg payload revealed an RMS of 0.9 mm, due to the simplifications of the kinematic model, i.e., not considering the friction and backlash effects. It was concluded that the designed robot could satisfy the mechanical requirements for being used as the robotic interface in a haptic large-organ laparoscopic surgery simulation system.

This study attempts to analyze the effect of diverse parameters of the peristaltic flow of second grade dusty fluid through a curved configuration. Stream function conversions are used to model the separate system of equations for the dust particles and fluid. The Perturbation technique is used to get the analytical solutions and the results are verified through graphs. It is noticeable that the trapped bolus, compresses both the dust particles and fluid with an increase in `the second grade parameter'. Moreover, a surge in `the Reynolds number' Re effects the bolus trapped in the lower portion of the channel for fluid. Decrement in the velocity is observed with a rise in `the wave number' \delta and `the second grade parameter' \alpha_1.

In the current research, numerical analysis was used to investigate the flow behavior through the axial jet-pump with various mixing chamber configurations (straight pipe and straight pipe-diffuser-straight pipe) in the presence of inlet swirling flow and its influence on the pump performance. The effects of introducing inlet swirling flow in the suction chamber and in the motive flow line, are numerically investigated. The optimum swirl angle in the suction chamber is found to be 45o which yields the maximum pump efficiency of 38.08 % for the second configuration of mixing chamber system. Consequently, the inlet swirl generally decreases the desired mixing chamber length. Additionally, the new mixing chamber configuration enhances the mixing process compared with the traditional mixing chamber. On the other hand, imparting a swirl in the motive line inversely affected the pump performance. Engendering a swirl in suction chamber causes an improvement by 12.76 % in the pump efficiency compared to the same pump configuration without swirl. The optimum tail pipe diffuser angle is found to be 3o.

The presented work aims to develop a novel technique for solving a general form of both linear and nonlinear partial differential equations (PDEs). This technique is based on applying a collocation method with the aid of Bernoulli polynomials and the use of such an algorithm to solve different types of PDEs. The method applies the regular finite difference scheme to convert the model equation into a system of a linear or nonlinear algebraic equation and then this system is solved using a novel iterative technique. Then, by solving this system an unknown coefficient is acquired and an approximate solution for the problems is achieved. Some test results of famous equations including the telegraph, viscous Burger, and modified Burger equations are presented to demonstrate the effectiveness of the proposed algorithm along with a comparison with other related techniques. The method proves to provide accurate results in terms of absolute error and through graphical representation of the solution.

The separation of a fluid from an immiscible liquid can be used in many natural ways. Traditional methods are currently used to accomplish this process. In this study, we attempted to investigate the effect of changes in the geometric radius of the water droplet in the oil medium and applied voltage to provide outputs which can be used to better design water separating electro-filter for crude oil. Furthermore, the most important innovation of this article is to study considering the effects of the presence and absence of Earth's gravity. The results of this work show that changes in geometry and voltage were effective in the deformation and movement of the drops, but their effects were not significant compared to the presence and absence of gravity. In other words, the effect of considering Earth's gravity in this study tends to make the results realistic, and the results would not be comparable to those obtained in the absence of Earth's gravity.

Convergent/divergent channels have real-world applications including the production of fibers and glass, the fabrication of plastic sheets, the manipulation of molten metal streams, and the industrial casting of metal. This article intends to discuss the flow and thermal transport of mixture of nanoparticles, namely, copper and molybdenum oxide in a base fluid (water) over a wedge-shaped channel. The dissipation effects are taken into account. To understand the thermophysical characteristics of the nanoparticles, the Yamada Ota model is selected. By using similarity transformations, the partial differential equations are converted into ordinary differential equations. The numerical solution is developed by applying the bvp4c built-in MATLAB. The impact of irreversibility effects are also incorporated. Moreover, the outcomes for wall stress parameter and Nusselt number are calculated as function of pertinent parameters. It is noted that the momentum and energy of the system are reduced due to accretion in the nanoparticles volume fraction of copper for both hybrid nanofluids and conventional nanofluids. For both convergent and divergent channels, heat transport is an increasing function of Brinkman number. The numerical values of thermal transport are developed for a specific range of Brinkman number and decreased for Reynolds number.