INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE (ENGLISH)
Year:2005 | Volume:16 | Issue:3|Papers Count:9

This paper introduces a new structure in neural networks called as TD-CMAC (Time Delay Cerebellar Model Articulation Controller), an extension to the conventional CMAC.,TD-CMAC has reasonable ability in time series prediction and requires fewer memory sizes. The suggested new model, the conventional CMAC and the classical multi-layer perceptron neural network (MLP) are demonstrated and validated for one-day-ahead prediction of daily minimum/maximum temperature. The comparison between different models shows that the TD-CMAC is likely to be suitable for our purpose.      

This article analyses different design issues of digital to analog interfacing for the uplink of a mobile communication system with smart antennas in the context of third generation (3G) mobile communication systems. The work initially targets a smart antenna test bed with non-real time processing, but the results can be employed for both real time and none-real time cases. The article also presents the novel idea of calculating the required quantization levels based on the combination of clipping and quantization noise.      

Maintenance reliability and efficiency in industrial hydraulic systems operation has become a point of concern for the professionals in maintenance engineering. One practical approach in this regard is the realization of symptoms of early stage malfunctioning in fluid power systems after which maintenance planning and preventive means would follow upon a reasonably accurate and subsequently acceptable determination. Among the highly reliable sources providing such convenience, Artificial Neural Network (ANN) stands a high chance of success neural network method has been used to detect faults occurring in most hydraulic systems. These faults could be related to supply pressure, effective bulk modulus and total leakage. The simulated system in this study consists of hydraulic servo valve, double acting cylinder and a spring that resists piston movement. Two main reasons causing this system to have a nonlinear behavior are hydraulic servo valve and compressibility effect of hydraulic fluid. The neural network approach in this investigation comprises of an efficient use in nonlinear systems and requires advance knowledge about the system behavior under faulty conditions and assumptions about the type and severity of faults likely to occur. Neural networks trained with different training algorithms are investigated. After training the network, the system was examined for different inputs and obtained results were compared.      

In this paper, methods are presented for decomposing the Laplacian matrices of graphs having special symmetries. These graphs have special connectivity properties and correspond to matrices of attractive canonical forms. These forms are applied to the free vibration analysis of symmetric frame structures, and calculating the buckling load of symmetric planar frames.    

This paper deals the determination of a stable solution for an Ill-posed inverse heat conduction problem (IHCP). By using the Chebyshev polynomials base function an approximate stable solution to the IHCP will be determined in finite or infinite domain.    

Reynolds-averaged compressible Navier-Stokes equations are solved using an implicit dual-time method on unstructured grids. The unstructured grid is generated using a novel successive refinement method where the surface and field grids are generated simultaneously. Point and line sources are distributed in order to obtain the required grid length scales within the domain. The governing flow equations are discretised by an implicit approach in a real time basis while at each real time step marches the solution in a pseudo-time through an explicit time marching scheme. This approach allows the real time step to be chosen on the basis of accuracy rather than stability and it is not required to solve the large system of equations simultaneously. The k - ε turbulence model equations are solved together with the main flow equations in a fully coupled manner. Results are presented for several laminar and turbulent test cases and comparisons of the calculated pressure and skin friction coefficient distributions with the reference data showed good agreements. Considerable computational savings are also achieved using the present implicit scheme over the fully explicit method.    

If teamwork is the key to effective organizations, information technology is the key to effective teamwork. The first part of this paper introduces the concept of using teams and information technology to effect organizational performance. Each element on the left side of this "equation" (the teams and the information technology) is of equal importance in bringing about the "result" (organizational performance); in fact, the synergistic relationship between teams and information technology makes them far more effective agents of change together than either could be apart. In the second part of this paper a quantitative model is presented that makes clear the significance of this relationship and presents the basic components of the process intended to exploit it: the mutual design of teams and information technology.      

The monthly wind speed data are used to determination of a Weibull density distribution function for Manjil wind energy plant in Iran. The data collected during a five years period from 1993 to 1998 and reported by the Iran's Meteorological Organization. The results show that the numerical values of the shape parameter vary between 0.87 and 1.64, whereas the value of the scale factor is found to vary between 4.09 and 10.25 m/s. It is also concluded from this study that the wind data are very well represented by the Weibull distribution function.