Year:2005 | Volume:39 | Issue:4 (92)|Papers Count:13

This study presents two mixed integer programming models for scheduling hybrid flow shops with sequence dependent setup times. In the first model, we assumed the machines at each stage are identical, but in the second model the machines at each stage are different. These models may be used to determine optimal solutions for hybrid flow shop problems of moderate size, and these problems could then be used as benchmarks for testing new sequencing heuristics.

A full-wave electromagnetic analysis of microelectromechanical switches (MEMS) in microwave and millimeter waves is presented in this paper. The fields are obtained by solving Helmholtzs equation using HFSS which uses finite element method (FEM). The switch is assumed as a two- port structure and the S- parameters are deduced from the fields. Characteristics of the switch over 1-60 GHz band, i.e. insertion loss in ON state and return loss in OFF state are obtained as 0.02-1.22 dB and 14-60 dB respectively over 1-60 GHz range. The MEMS is also considered as a capacitor and is approximated with lumped elements. Using scattering parameters and the elements of the transmission matrix, the operation of the switch is analyzed and compared with the full-wave analysis results. Finally, the S-parameters for different dimensions and frequencies are determined. These characteristics are of great importance in computer aided design (CAD) of high frequency circuits.

In this paper, a homonymic omni-directional mobile robot is introduced. The developed robot is based on ordinary differential drive mechanism with an extra joint. That joint is mounted on the base in an off-centered location from the wheels axe. Using ordinary wheels, the robots mechanism and its control system remain simple while it is capable of moving on different surfaces along complicated paths in indoor environments. A kinematic model of the robot is driven and analyzed. Also, an appropriate dead-reckoning system and a path tracking module are developed and a proper control system is designed. The experimental results are provided to show the mobility of the developed robot and the controllers performance. The results show that the robot is capable of moving in arbitrary directions from any configuration. It is also able to negotiate tight turns.

In this paper, we have a brief overview on advantages and disadvantages of dynamic logic design. To reduce the excessive power consumption of normal dynamic logic circuits, Data Driven Dynamic Logic or D3L is introduced. D3L also provides enhancements in reducing area and delay of a logic gate which has been confirmed by simulation results. Next, it is shown how different functions can be implemented in dynamic logic and then converted to an equivalent D3L design. To validate our simulation results, two 16-bit barrel shifters are implemented in an industrial 5-V, 0.6 m CMOS process: one in normal Domino logic and the other in our proposed D3L. Experimental measurements are in accordance with post-layout simulations and show that, depending on input patterns, a D3L shifter consumes 8% to 62% less power, and is 29% faster than the equivalent Domino circuit. In addition, it provides 9% area advantage over its Domino rival.

The amount of signaling traffic due to mobility management will increase significantly, in mobile networks. Using timing based profiles of subscribers mobility, will reduce location updating, and increase the amount of paging.In this paper we offer a trainable method which provides a timing base profile for mobility through linked lists which locates the subscribers according to his/her past history of his/her movements. This method reduces location updating significantly and increases paging modestly.

In this paper a novel constructive neural network is introduced for solving the classic traveling salesman problem (CNN-TSP). The proposed neural network is inspired by the idea of the Kohonen SOFM and the Hopfield NN. The Kohonen SOFM introduces suitable TSP solutions for its competitive training algorithm though it slowly converges. Contrarily, the Hopfield NN quickly converges for its recursive structure while its solutions are poor. The proposed CNN combines the recursive structure (inspired from the Hopfield NN) with the competitive training algorithm (inspired from the Kohonen SOFM) to give both suitable performance and quickly convergence. The experimental results show that the CNN convergence speed is faster than the Kohonen SOFM by 20 times while its performance (with respect to the best-to-date solutions) is better than Kohonen by 3.81% for 29 benchmark TSP problems from TSPLIB. Also, the proposed NN appears better performance than other conventional approaches such as simulated annealing and Budinichs SOM. CNN can be used to solve other optimization NP-complete problems for its flexibility; i.e. in this paper, it is used to solve shortest path problem with specified city number (SPSN) as well as TSP.

In this Paper, implementation of brain emotional learning intelligent controller (BELBIC) for real word applications is described. Intelligent controllers with learning and adaptively are replacing with classical control methods in various fields of industry. Emotional controllers are members of the broad class of intelligent controllers that are inspired from the emotional learning in human and some animals. BELBIC that is based on computational model of Amygdale (center of emotional learning in the brain) is explained in this paper. Single input-single output BELBIC has some parameters. A good behavior of control system achieves with fine tuning of these parameters. Good results in simulations are obtained for BELBIC applied to several linear and non-linear plants. However, some considerations are necessary when a controller is applied to a real world system. In this paper an applicable method for computer control of a real world system that is purposeful for educational environments in Iran is proposed. This method is applied to speed control of DC servo motor using BELBIC and a PID controller. The DC servo motor and interface hardware are modeled and the whole system is simulated in order to finely tune the parameters of the controller. Experimental results show excellent results for BELBIC in comparison to a classic controller and also show that the proposed method is satisfying for computer control purposes.

In this paper Mode-Matching Technique is implemented in the analysis of corrugated horn antenna. Furthermore, a new method for optimization of corrugated horn antennas is presented using Genetic Algorithm and the mode matching technique. Four corrugated horn antennas in X-band are designed using this approach. In three of the cases a corrugated horn antenna which was previously designed with conventional methods is optimized and good result was obtained. The results show the ability of genetic algorithm in design and optimization of corrugated horn antennas.

Sectionalizing switches can be employed for service reliability enhancement in primary distribution systems. In this paper three models are proposed for optimal allocation of sectionalizes. In the first model, the aim is to minimize the outage, maintenance and investments costs with respect to restriction in capital budget. In the second model, the aim is to meet the minimum outage cost using maximum capital resource available while in the third one, the aim is to meet the certain level of reliability using minimum number of switches. All models are solved using genetic algorithm (GA) as the optimization tool. The performance of the proposed approaches are assessed and appreciated by various case studies on urban distribution system connected to bus 2 of the RBTS and a real distribution system from Iran.

There is no generally conventional definition of subsidy. For the purposes of this paper, a subsidy is a transfer of economic resources by the government to the buyer or seller of a good or service that has the effect of reducing the price paid, increasing the price received, or reducing the cost of production of the good or service. Energy Subsidy is paid by government so that all classes of society can gain a minimum level of welfare. So, the purpose of energy subsidy is to help deprived groups and acquire social justice. But if Energy subsidy is paid indirectly (providing energy at a price lower than marginal cost), subsidy works against the mentioned purpose. In this way, high-income groups have a much higher share of energy consumption. As a result, for having a goal-oriented energy subsidy, direct energy subsidy method (pay the sum of subsidy directly to low-income groups) is the main proposed in this study. Changes in energy prices have great impacts on economic, social and political sectors of the country. The effects of above method on the four variables have been studied here: inflation rate, economic pressure on low-income groups (which is showed as the ratio of inflation rate to income increase rate of low class), energy consumption per capita and energy smuggling. The structure of direct energy subsidy has been modeled with system dynamics methodology first, four scenarios have been proposed and finally the affects in fluctuation of energy price on these variables have been analyzed in each of the scenarios.

Positivism paradigm in natural science overcomes to the others and "hypothesis test" is the most important research method in this paradigm. The overcome of this method to the other of scientific field, especially in human science, is one of the big problems and main obstacle of researches in these fields. The main reason is to derive from overcoming Newtonism to researchers due to the kind of sciences training in high school and university. On the other side, another reason for this is inadequate researcher's knowledge in the interpretive paradigm method. This leads to use hypothesis testing incorrectly and not using the other methods in the proper manner. Now in information systems field, the interpretive paradigm is overcame to others. In this paper, we will first discuss about researches in this area statistically and then illustrate a conceptual framework to introduce the "systems development" method. In this paper, our research method is conceptual study. We illustrate that how we can use this method to overcome the distances between the theory and practice. Finally, a case study will be illustrated by using this method.