Connection Admission Control (CAC) is one of the resource allocation functions which plays a significant role to ensure Quality of Service (QoS) provisioning in wireless networks. To meet connection requirements, and achieve bandwidth efficiency with less computation complexity, we present a CAC mechanism for OFDMA-based WiMAX networks which uses fuzzy sets and fuzzy logic theory to admit new incoming connections. The proposed algorithm estimates traffic load, available bandwidth and incoming connection required bandwidth to decide whether accept or reject a new incoming connection. The fuzzy logic-based CAC system is simulated using MATLAB to investigate its effectiveness in terms of incoming connections blocking probability. The simulation results show improvement in the blocking probability for both UGS and non-UGS services compared to Fuzzy Logic Based Admission Control Method in Wireless Networks (FLACWN).

This paper provides an effective method to evaluate the input quantization and multiplication roundoff errors for two-dimensional (2-D) separable-in-denominator recursive digital (SDRD) filters. This work is based on the partial fraction expansion of 2-D SDRD filters [1] and their modular implementation structures [2] proposed by the authors. Equations are derived for the calculation of roundoff errors for various implementations of 2-D SDRD filters. An example is given to demonstrate the application of the proposed method.

In this paper, several control strategies for water management of proton exchange membrane (PEM) fuel cells are presented. The controllers were designed, developed and implemented in Fuel Cell Laboratory at Florida Atlantic University (FAU) in order to increase the efficiency and performance of PEM fuel cells. Two different pulsing approaches were implemented. The amplitude variations of the pulses were controlled through a regulator on the air source pump. Other parameters were tuned using computer software in conjunction with A/D, D/A, and electronic circuits. In addition, a fuzzy controller is proposed for water management of PEM based on Mamadani inference systems. The preliminary experimental results demonstrate the effective of the method.

A new model reduction concept and approach is proposed. In this approach the order of a large-scale system is reduced in the neighborhood of crossover frequency in order to retain stability and performance of the full order system. This concept very closely preserves the gain and phase of the original system. In this approach, the full order system is perturbed and reduced within its specified frequency bandwidth. The concept is applicable to both open and closed-loop systems. To illustrate the effectiveness of the proposed concept and approach a benchmark 4th order plant model is reduced to a 2nd order. For the same 4th order system, two distinct approaches are applied to design two distinct 2nd order H/sub /spl infin// controllers. The simulation results of the two controllers are compared.

This paper, the preliminary results pertaining to development of a prototype interdisciplinary undergraduate fuel cell laboratory is presented. The development of the new laboratory is carried out through innovations and recent advances in fuel cell technology and effective implementation of these techniques to substantially improve the instructional capability of undergraduate instruction. Such a goal is achieved through collaboration with several leading industries in fuel cell technology including Teledyne Energy System Inc. (TESI) and Energy Proton System Inc. These industries have extensive experiences in design, fabrication and implementation of fuel cells in both stationary and mobile applications. Students from various engineering disciplines are benefiting from opportunities the laboratory provides in design, experiment and simulation of fuel cells.

A multidimensional iterative model for the control analysis of two cooperating robots is proposed. The manipulation of a rigid object with elastic restraint between the object and the end effectors using the proposed model is investigated. The scheme is based on an iterative structure which utilizes available data from the previous operations. These data consist of positions and velocities of the actual trajectories and applied forces to the object at the points of contact. It is shown that the convergence of the actual trajectory for the manipulation of the rigid object to the desired one is guaranteed upon proper selection of two weighted control matrices.>

In this paper, the problem of block optimal realizations of separable-in-denominator 2-D filters are considered. A general partial fraction expansion of a denominator separable 2-D transfer function is presented. Based on such expansion a new block optimal realization is derived with emphasis on real time processing in a multiprocessor environment. A criterion for the absence of limit cycles for a second order 2-D block is proposed.>

A waveform substitution technique using interpolation based on the slowly varying speech parameters of short-time energy and zero-crossing information is developed for a packetized speech communication system. The system uses 64-kb conventional pulse code modulation (PCM) for encoding and takes advantage of active talkspurts and silence intervals to increase the efficiency of utilizing a digital link. The short-time energy and information on the zero-crossings needed for the purpose of determining talkspurts are transmitted in a preceding packet. Hence, when a packet is pronounced lost, its envelope and frequency characteristics are obtained from a previous packet and used to synthesize a substitution waveform which is free of annoying sounds that are due to abrupt changes in amplitude.>

The approximation and optimal implementation of a digital filter with fixed-point arithmetic are investigated. A minimum-order structure is derived which minimizes an upper bound error due to the order approximation and output round-off noise. It is found that the minimum-order structure exhibits some favorable properties, such as absence of limit cycle and robustness of the filter's constant coefficients. A numerical example is presented to illustrate the proposed design technique.>

The approximation and optimal implementation of a single-input single-output multidimensional digital filter with fixed-point arithmetic is investigated. Based on balanced and optimal realizations, a novel structure which minimizes the error due to the order approximation and output round-off noise is obtained. It is shown that for the class of M-D completely separable-in-denominator filters, optimum order structure exhibits some favorable properties such as robustness of the filter's constant coefficients. A numerical example is presented to illustrate the proposed technique.>

The optimal synthesis of a SISO multidimensional (M-D) digital filter with fixed-point arithmetic is investigated. A general upper bound on the sensitivity measurement of the filter's eigenfunctions is proposed. It is shown that for optimal realization this bound attains its minimum value. It is found that the optimal realizations of M-D filters demonstrate a remarkable property in needed number of multipliers per sample output. A numerical example is presented to illustrate the design procedure.