International Journal of Engineering
Volume:18 Issue: 2, May 2005

This paper presents experimental analysis of wheeled mobile robots. Mathematical modelling of the mobile robot is presented. The mobile robots consist of an omni-directional and three differential drive mobile robots are tested and moved in given trajectories and the systematic errors of the robots are determined. A new method for omni-direction mobile robot was introduced in which the robot was programmed to move in direction of each wheel shaft. Finally, the mobile robot is moved in given trajectories and the systematic errors of the robot are determined.

In this paper, it is shown that group method of data handling (GMDH)-type neural networks and their application can be effectively used to acquire the inverse kinematic equations of a Puma760 robot manipulator based on the numerical data of its motion. The aim of such modeling is to show the accuracy of GMDH-type neural networks. For evaluating the accuracy of the obtained equations, a new trajectory is employed to demonstrate whether the models are still valid or not. Finally, the best results are used to define the inverse kinematic equations.

In design of anaerobic bioreactor, rate equation is commonly used. Mathematical model was developed at steady state condition, to project concentration of gaseous substrate and product in biological oxidation of carbon monoxide with water to produce hydrogen and carbon dioxide. The concept of bioconversion was based on transport of CO from gas phase to liquid phase, as the CO consumption was instantaneous and the moles of CO in liquid phase was oxidized to CO2, and H2 was liberated from water. The moles of produced H2 were identical to the moles of CO transported to the fermentation media. The data was experimentally obtained in a continuous stirred tank bioreactor. A photosynthetic bacterium, Rhodospirillum rubrum, was used as biocatalyst to facilitate the oxidization of carbon monoxides via water-gas shift reaction. The rate of CO consumption and hydrogen production were projected based on dynamic model at steady state condition. The experimental data were fitted to a few rate models and the best suitable dynamic model for hydrogen production was obtained. The model was used for scale up calculation and dependency of the rate equation and the model to a few process variables were analyzed. The liquid phase medium was supplied for microbial growth with initial concentration of 4. The media flow rate to the reactor space time (F/VL) was 0.2 h-1. At the steady state condition, the concentration of acetate was independent of the dilution rate and it was approximated about 1.5 g/l.

The synthesis of citronellyl butyrate by direct esterification reaction catalyzed by immobilized lipase from Candida rugosa was studied in a continuous packed bed reactor using n-hexane as organic solvent. Parameters such as residence time, temperature, and pH were examined. The optimum conversion was obtained at a flow rate of 1 ml/min (residence time 8 min), temperature of 50 °C, and pH 7.5. At high temperature, biocatalyst was rapidly deactivated with respect to time. The immobilized lipase was stable at pH range of 6 to 9. The deactivation of biocatalyst was increased at pH of immobilized lipase 4 and 10 in comparison with pH range from 5 to 9. The esterification reaction in packed-bed reactor was modeled by ping pong model and ping pong with product inhibition model. The observed kinetics behaviour of esterification reaction was found to follow a ping pong with product inhibition model. In this study, the conversion of butyric acid and stability of immobilized lipase was higher in the system with molecular-sieve than in the system without molecular-sieve.

Growth of the world population, increasing demand for fossil fuel consumption and consequently increasing threat of global warming, has extended the need for production and use of clean fuels and normal hydrogen is an important utility in the production of clean fuels. In this paper, a mathematical optimization method is applied which is based on non-linear programming of superstructure for minimizing the consumption of hydrogen. The method considers all the pressure constraints and is suited for revamping industrial systems. The optimum placement of new equipments like purification unit has been also considered. It is tried to verify the method adopted, in addition, an industrial case study has been carried out.

This experimental work deals with the effects of skewness on the shearing properties of the worsted woven fabric. Shearing properties of 160 samples are measured by two methods (KES and concentrated loading methods) and the results are compared. Both methods show a positive correlation between skewness and shear rigidity indicating, as the skewness goes up the shear rigidity also increases. Correlation between shear rigidity evaluated by KES and skewness was 0.725, but new parameter (EML) extracted from the concentrated loading curve (Extension at 200 gram-load) showed more sensitivity to fabric skewness and gave a higher correlation (-0.866) to it. In other words, the concentrated loading method shows the relationship between skewness and the shear rigidity (G).

The amount of seepage which crosses the body of earth dams is considered by several scientists. Despite of these researches and studies that carried out by technical experts and scientists, still the effect of positioning horizontal filter blankets on two and three dimensional seepage analysis are not analyzed in full details. In this paper, the effects of variation in the location of the horizontal filter blankets are studied. The results showed that the amount of flux is greatly influenced by the place of the horizontal filter blanket and it has more effect on flux in three-dimensional models than that of two-dimensional ones.

Anti-lock braking systems (ABS) have been developed to reduce tendency for wheel lock and improve vehicle control during sudden braking especially on slippery road surfaces. The objective of such control is to increase wheel tractive force in the desired direction while maintaining adequate vehicle stability and steerability and also reducing the vehicle stopping distance. In this paper, a genetic-fuzzy ABS controller is designed. The objective function is defined to maintain wheel slip to a desired level so that maximum wheel tractive force and maximum vehicle deceleration are obtained. All parameters of membership functions and rules of the fuzzy system that is Takagi-Sugeno-Kang (TSK) type are obtained using a genetic algorithm. Simulation results show very good performance of the controller for different road conditions.

Among various frameworks of intelligence, in general, feed-forward perceptron neural networks (FPNN) is a useful and common method, because of the network\''s ability to approximate highly nonlinear functions. Similarly, among various paradigms of learning, evolutionary-based algorithms such as genetic algorithms (GA) have gained increasing interest in recent years due to their ability to locate globally optimal solutions in nonlinear, noisy and uncertain problem domains. Here, we propose a cooperative co-evolutionary strategy for finding weights and structure of FPNN simultaneously. The new algorithm allows for separate populations of weights and structures of neural networks to coexist and cooperatively evolve thru two separate genetic algorithms. The proposed algorithm is simulated in RoboSoccer multi-agent environment, and is used for learning the "ball interception" skill of robot soccer players. Also, the convergence properties of the new algorithm are statistically compared with two other approaches as well as standard back propagation (BP) algorithm. Simulation results indicate that the proposed co-evolutionary approach is superior in terms of consistently finding improved solutions.