Improved Dijkstra Algorithm for Mobile Robot Path Planning and Obstacle Avoidance

Optimal path planning avoiding obstacles is among the most attractive applications of mobile robots(MRs)in both research and education.In this paper,an optimal collision-free algorithm is designed and implemented practically based on an improved Dijkstra algorithm.To achieve this research objectives,first,the MR obstacle-free environment is modeled as a diagraph including nodes,edges and weights.Second,Dijkstra algorithm is used offline to generate the shortest path driving the MR from a starting point to a target point.During its movement,the robot should follow the previously obtained path and stop at each node to test if there is an obstacle between the current node and the immediately following node.For this aim,the MR was equipped with an ultrasonic sensor used as obstacle detector.If an obstacle is found,the MR updates its diagraph by excluding the corresponding node.Then,Dijkstra algorithm runs on the modified diagraph.This procedure is repeated until reaching the target point.To verify the efficiency of the proposed approach,a simulation was carried out on a hand-made MR and an environment including 9 nodes,19 edges and 2 obstacles.The obtained optimal path avoiding obstacles has been transferred into motion control and implemented practically using line tracking sensors.This study has shown that the improved Dijkstra algorithm can efficiently solve optimal path planning in environments including obstacles and that STEAM-based MRs are efficient cost-effective tools to practically implement the designed algorithm.

Three-dimensional analysis of natural convection in nanofluid-filled parallelogrammic enclosure opened from top and heated with square heater

A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.

Effects of using sinusoidal porous object(SPO)and perforated porous object(PPO)on the cooling performance of nano-enhanced multiple slot jet impingement for a conductive panel system

Cooling system design for thermal management of electronic equipment,batteries and photovoltaic(PV)modules is important for increasing the efficiency,safety operation,and long life span the products.In the present study,two different cooling systems are proposed with nano-enhanced multiple impinging jets for a conductive panel.The present cooling systems can be used in electronic cooling and PV modules.Perforated porous object(PPO)and sinusoidal porous object(SPO)are used in the jet cooling system.2D numerical analysis usingfinite volume method is conducted considering different values of permeability of the objects(Darcy number(Da)between 10^(-6) and 10^(-1)).When PPO is used in the cooling system,num-ber of cylinders(between 1 and 6),and size of the cylinders(between 0.015 and 0.075)are considered.In the case of using SPO,amplitude(between 0.1 and 2)and wave number(be-tween 1 and 12)are varied.Alumina-water nanofluid with cylindrical shaped nanoparticles is used as the heat transferfluid.When permeability is changed for PPO,the average temper-ature increases by roughly 3.89℃ for a single cylinder and drops by roughly 0.57℃ for a six-cylinder cases.Increasing the size of the cylinder in the PPO case at highest permeability results in temperature drop of 5.3℃.When changing the number of cylinders,cooling rate varies by about 3.6%.Wave number of SPO is more influential on the cooling performance enhancement as compared to amplitude and permeability of the SPO.The average surface temperature drops by 12.4℃ when the wave number is increased to 12.As compared to reference case of jet impingement cooling without porous object,using PPO and SPO along with the nanofluid result in temperature drop of 12.3℃ and 14.4℃.

Unsteady Flow of Hybrid Nanofluid with MagnetohydrodynamicsRadiation-Natural Convection Effects in a U-Shaped Wavy Porous Cavity

In this paper,the unsteady magnetohydrodynamic(MHD)-radiation-natural convection of a hybrid nanofluid within a U-shaped wavy porous cavity is investigated.This problem has relevant applications in optimizing thermal management systems in electronic devices,solar energy collectors,and other industrial applications where efficient heat transfer is very important.The study is based on the application of a numerical approach using the Finite Difference Method(FDM)for the resolution of the governing equations,which incorporates the Rosseland approximation for thermal radiation and the Darcy-Brinkman-Forchheimer model for porous media.It was found that the increase of Hartmann number(Ha)causes a reduction of the average Nusselt number(Nu),with a maximum decrease of 25%observed as Ha increases from 0 to 50.In addition,the influence of the wall’s wave amplitude and the heat source length on the heat transfer rate was quantified,and it was revealed that at high wave amplitude,the average Nu increases by up to 15%.These findings suggest that manipulating magnetic field strength and cavity geometry can significantly enhance thermal performance.The novelty of this is related to the exploration of a U-shaped wavy cavity,which is not covered in previous studies,and to the detailed examination of the combined effects of magnetic fields,radiation,and hybrid nanofluids.