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Date 20-22 March 2006

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Displaying Results 1 - 25 of 88
  • Increasing the efficiency of interconnects using a compensating circuit

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (86 KB) |  | HTML iconHTML  

    It is shown that the efficiency of an arbitrary previously designed interconnect can be increased using a suitable compensating circuit at its far end. A lossless lowpass circuit is considered for this purpose and its element values can be obtained by an optimization method. The proposed idea is evaluated using an example. View full abstract»

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  • Application of hybrid genetic algorithms to design optimal radial network

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (65 KB)  

    The document that should appear here is not currently available. View full abstract»

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  • Optimized and adaptive link state routing strategy

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (78 KB) |  | HTML iconHTML  

    The dominant link state protocols like OSPF despite their advantages require the flooding of new information across the entire routing area after changes in any link state. With the growth of the network diameter or the frequency of link-state changes increases, the overhead in terms of bandwidth and processing cost, of flooding becomes prohibitive. Furthermore, such flooding over a large area will cause unnecessary overhead on the links, potentially creating many transient routing loops that can last for a long time. This limits the scalability of the routing protocols to large routing areas. To overcome such problems, we present in this paper an Optimized and Adaptive Link-State Protocol (OALP), a modification to the existing link-state routing protocol that does not require the state of each link to be flooded to the entire internetwork all the time, or to entire areas if we monitor the activity status of the nodes in the internetwork. Thus minimizing the amount of information distributed by link-state routing protocols. There are primarily two modes in which we devise the network to operate depending the activity levels of the incumbent nodes. Depending on the activity levels an optimized flooding procedure is provided which would greatly reduce the number of advertisements flowing through the network. View full abstract»

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  • A wireless propagation channel model with meteorological quantities using neural networks

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (87 KB) |  | HTML iconHTML  

    Deterministic channel modeling approaches are slow to run, require a detailed description of the environment (which is sometimes expensive or even impossible to obtain) and may be difficult to implement. A new approach for the modeling of wireless propagation in LOS environment is presented. We treat the meteorological conditions by weather variations through using neural networks. The aim of the paper is to propose a neural model for understanding the relation between the path loss, the propagation delay and the atmosphere parameters such as humidity, pressure, temperature. It is clarified the propagation factors affecting the wireless channel in the frequency range 300 MHz to 100 GHz. We use grey box approach based on fundamental principles of radio wave propagation physics and measurement data. To verify the accuracy of the model, evaluation and validation of the model are performed by simulating the channel using different sets of actual data from different situations. It is shown that this model can handle unusual atmosphere conditions and the model can be applied to better calculate the delay propagation. View full abstract»

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  • Performance analysis of layered space-time codes in wireless communications channels

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB) |  | HTML iconHTML  

    The objective of this paper is to simulate numerically the wireless channel and the V-BLAST architecture to compare the performance of these systems using linear nulling and symbol cancellation along linear nulling for a zero forcing (ZF) and a minimum mean-squared error (MMSE) receiver. We will also compare the performance of V-BLAST and the Successive Cancellation Receiver (SUC) against the QR decomposition as an approximation of V-BLAST, trying to develop a less calculation intensive algorithm. The simulation will compute the frame error rate in both cases for different values of SNR in a flat fading channel. The transmitted symbols will be modulated using a QPSK constellation with 4 transmitters and 6 receivers. The results will be compared to those measured in the laboratory of the optimum V-BLAST. View full abstract»

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  • Investigation of torque development in SRM under single phase excitation

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (142 KB) |  | HTML iconHTML  

    This paper presents the results of an investigation of torque development in the air gap of a 6/4 and 8/6 switched reluctance machines (SRM). Due to the force components acting on the rotor enables us to provide more accurate picture of the torque generation and vibration in this family of electric machines. The analysis for the torque is computed by finite element method. The torque optimisation is investigated by changing the pole arc/pole pitch ratio (y) of the stator, rotor and yoke dimensions. View full abstract»

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  • Analysis and torque optimisation of switched reluctance motor

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    This paper shows the developed torque of a 4 phase 8/6 poles switched reluctance motor by simulation tests. The analysis for the torque is computed by finite element method. The torque optimisation is investigated by changing the pole arc/pole pitch ratio (γ) of the stator, rotor and yoke dimensions. View full abstract»

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  • Investigating shielded enclosures with double-layers walls

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB) |  | HTML iconHTML  

    In this paper the use of double-layers walls for shielded enclosures is proposed to increase the shielding effectiveness of them. The effect of distance between two layers and the offset between two apertures in the shielding effectiveness is investigated. The usefulness of inserting a box between two layers around apertures is also presented. To analyze enclosures with double-layers wall, the eigenvector expansion and the Bethe's approximation have been used. View full abstract»

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  • AGC of a hydrothermal system with SMES unit

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB) |  | HTML iconHTML  

    In this paper, the AGC improvement of a two area interconnected hydrothermal system along with a Superconducting Magnetic Energy Storage is proposed. Generation Rate Constraints are also considered. Integral Squared Error technique is used to obtain the optimum values of the integral gain settings. Analysis reveals that the dynamic responses are considerably improved in the presence of the SMES unit. A comparison and analysis of the dynamic performances without and with SMES unit in the presence of GRC brings out the superior performance of the SMES unit in suppressing the frequency and inter-area tie-power deviations from their nominal values followed by a step load perturbation. View full abstract»

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  • Radio resource management issues for 3G and beyond cellular wireless networks

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (101 KB) |  | HTML iconHTML  

    Radio resource management (RRM) in the next generation wireless network system will have features and requirements that are quite distinct from current systems, mostly designed for non-heterogeneous and non-shared networks. Such features include radio resource sharing which is considered as one of the main future issues of RRM as network evolves towards 4G Radio resource sharing has an impact on system design in general and on radio resource management in particular. This paper presents a general RRM for 3G and beyond mobile wireless network supporting multi-services, referred to as general call admission control (GCAC). The aim of the proposed GCAC algorithm is to guarantee the required quality of service (QoS) and to maintain higher resource utilization. Simulation results indicate that the proposed GCAC provides higher resource utilization under all load conditions leading in turn to increased revenue. In addition, a higher quality of service for traffic is provided especially when we differentiate between the traffic classes. View full abstract»

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  • A QoS-Aware call admission control algorithm for 3G cellular wireless networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (127 KB) |  | HTML iconHTML  

    The 3G cellular mobile systems which are based on WCDMA technology are expected to be interference limited. Soft capacity is one of the main characteristics of 3G (i.e, UMTS) and it requires new radio resource management strategies to serve diverse quality of service requirements. In this paper, a WCDMA prioritized uplink call admission control (CAC) algorithm for UMTS, which combines QoS negotiation and service differentiation by priority, is studied. This CAC scheme gives preferential treatment to high priority calls, such as soft handoff calls, by reserving some bandwidth margin (soft guard channel) to reduce handoff failures. In addition, queuing is also used to enhance the handoff success probability. The algorithm uses the effective load as an admission criterion and applies different thresholds for new and handoff calls. Finally, the study considers two types of services: voice and data calls. Results indicate that this algorithm reduces the drop handoff calls and increases the total system capacity; hence the GoS and the system performance can significantly be improved especially in case of high mobility environments. View full abstract»

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  • Analytical modeling of call admission control schemes for multiclass traffic mobile wireless networks

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (146 KB) |  | HTML iconHTML  

    This paper studies and analyze two call admission control (CAC) schemes in multimedia cellular wireless networks. These call admission control algorithms are studied for different network configurations. These configurations include, employing the queuing techniques for voice handoff with finite lifetime, differentiating between voice and data calls in terms of the average channel holding time, data bandwidth requirements, and employing queuing techniques for voice handoff and data handoff calls with finite lifetime. The main contribution of this paper is the development of an analytical model for each of the two CAC algorithms specified in this study. In addition to the call blocking and termination probabilities which are usually cited as the performance metrics, in this work we derive and evaluate other metrics that have not be considered by previous work such as the average queue length, the average queue residency, and the time-out probability for handoff calls. We also develop a simulation tool to test and verify our results. Finally, we present numerical examples to demonstrate the performance of the proposed CAC algorithms and we show that analytical and simulation results are in total agreement. View full abstract»

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  • Intelligent nonlinear predictive control

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB) |  | HTML iconHTML  

    This research article presents a Fuzzy structure for a Model Predictive Control (MPC) system. MPC theorem has recently been incorporated with fuzzy models. Such an integration provides controller design methods for an MPC control system. The paper concentrates on aspects of fuzzy based MPC for multivariable systems. Mathematical formulation of linearized MPC is utilized to introduce the concept of fuzzy based MPC scheme, then fuzzy MPC is constructed based on a modeled pH reactor. View full abstract»

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  • Robotics system optimal task control (neuro-inverse kinematics approach)

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    A fast and efficient method for computing optimal grasping and manipulation forces is presented based on a Quadratic Optimisation formulation for a hand robotics system, where computation has been based on using the non-linear factual model of contacts. Furthermore, in order to achieve grasping while in motion, the Hand Inverse Jacobian has to be intensively computed, consequently, we investigate an efficient approach of employing an Artificial Neural Network for the multi-finger robot hand in which the object motion is defined in. The approach followed here is to let an ANN to learn the nonlinear Inverse Kinematics functional relating the hand joints positions and displacements to object displacement. View full abstract»

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  • Application of cascade correlation neural network in modelling of overcurrent relay characteristics

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (201 KB) |  | HTML iconHTML  

    Modelling of Overcurrent (OC) relays with inverse time relay characteristics is a vital job for coordination of these relays. There are many publications in which the OC relay characteristics have been modelled. In this paper a new model based on cascade correlation neural network is proposed. The cascade correlation neural network is used to calculate operating times of OC relays for various Time Dial Settings (TDS) or Time Multiplier Settings (TMS). This method can cover nonlinearity of the characteristic and its accuracy is much higher than the polynomial and the other neural networks models such as perceptron and backpropagation neural networks models. The method is tested on three types of OC relays and the results obtained shows, the accuracy of the new method is higher and therefore it is more useful than the others. The model is validated by comparing the results obtained from the new method with nonlinear analytical, perceptron and backpropagation neural networks models. View full abstract»

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  • A new eigen decomposition based algorithm for beamforming in CDMA communication systems

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (83 KB) |  | HTML iconHTML  

    A new adaptive beamforming method for direct sequence code division multiple access (DS-CDMA) communication systems is proposed, which has low computational load. The proposed method needs only 2N+1 complex multiplications and 2N-1 complex additions, where N is the number of antennas in the array. We evaluate the performance of the proposed method in estimating the angle-of-arrival (AOA) of the desired signal and in producing the array beam pattern. Moreover, the performance of the proposed method in alleviating the probability of bit error in both fading and non-fading channel is verified. It is observed that although the proposed method has low computational load, nevertheless it has desirable performance. View full abstract»

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  • Effect of geometrical perturbation on the radiation pattern of parabolic reflector

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (62 KB) |  | HTML iconHTML  

    The radiation patterns of perturbed two dimensional parabolic reflector fed by a slotted circular cylindrical waveguide for both the TE and the TM modes are examined. The analysis is carried out using Green's function second identity in conjunction with the Moment Method. Results show that the perturbed geometry achieves various degrees of improvements in most antenna's characteristics over the plain parabolic reflector. View full abstract»

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  • An algorithm to solve the inverse kinematics problem of a robotic manipulator based on rotation vectors

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (215 KB) |  | HTML iconHTML  

    This paper presents an algorithm to solve the inverse kinematics problem for a complex wrist structure six degree of freedom (6DOF) robotic manipulator. The last three rotating axes do not intersect at one point and there are off axes in its coordinate frames. The proposed algorithm based on the rotation vector concept, which is also used to describe the orientation of manipulator end-effector. All the possible solutions of the inverse kinematics problem can be obtained by using the proposed algorithm which is tested practically on the MA2000 robotic manipulator. View full abstract»

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  • Optimizing the operation of current differential protection by power differential relay for three phase transformer

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    To avoid the needless trip by magnetizing inrush current, the second harmonic component is commonly used for blocking differential relay in power transformers. However, the main problems of the current comparison method are in the very high inrush currents and relatively small fault currents regarding winding short circuits. Also The second harmonic component in fault current is increased in long lines which may blocks the relay operation. This paper describes a method to discriminate internal fault from inrush current and faults with a high second harmonic component by the sum of active power flowing into the transformer from each terminal. The average power is almost negligible for energizing, but an internal fault consumes large amounts of power. View full abstract»

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  • Authenticated location in wireless mesh networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (231 KB) |  | HTML iconHTML  

    Location is part of the context of an ensemble of mobile nodes in a wireless mesh network. In this paper we present a concept and an architecture for a location aware Digital Rights Management system. This system uses signal strengths in a mobile ad-hoc or mesh network to determine the position of each node and to authenticate these position information. It enables devices to control access depending on their position. We describe algorithms, protocols, security threats, and a prototype. View full abstract»

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  • Allocating generation to loads and line flows for transmission open access

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    This paper presents a new method for calculating the individual generators' shares in line flows, line losses and loads. The method is described and illustrated on active power flows, but it can be applied in the same way to reactive power flows. Starting from a power flow solution, the line flow matrix is formed. This matrix is used for identifying node types, tracing the power flow from generators downstream to loads, and to determine generators' participation factors to lines and loads. Neither exhaustive search nor matrix inversion is required. Hence, the method is claimed to be the least computationally demanding amongst all of the similar methods. View full abstract»

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  • B-GRID: Location aware bandwidth efficient routing protocol for wireless ad hoc networks

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (106 KB) |  | HTML iconHTML  

    An Ad Hoc network results from a cooperative engagement of a collection of mobile nodes without requiring any intervention of any centralized access point. The term ad hoc means that the network structure in not permanent but it can take different forms depending on the task it needs to perform. An ad hoc on-demand routing protocol starts with route discovery procedure from a source to a destination. In this paper, we propose a bandwidth efficient routing protocol called Bandwidth efficient GRID (B-GRID). View full abstract»

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  • A new generalized approach for performance evaluation of communication systems with intentional/non-intentional jamming

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (169 KB) |  | HTML iconHTML  

    In this work, a new generalized approach is proposed to evaluate the probability of error performance of communication systems in the presence of interference. The interference can be intentional such as multitone jamming, or non-intentional such as multiple access interference or co-channel interference. As an example, the new approach is applied to compute the exact probability of error for a frequency hopping spread spectrum system with noncoherently demodulated M-ary amplitude shift keying signal in the presence of multitone jamming and white Gaussian noise. View full abstract»

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  • Soft-decision decoding of systems with Tx/Rx diversity

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB) |  | HTML iconHTML  

    In this paper, we describe the concatenation of Turbo/Convolutional codes with transmit and receive diversity schemes by using Space-Time Block Code. It is shown that, by using two transmit antennas and one/or two receive antenna, large coding gain for the bit error rate is achieved over the system without diversity. Simulation results show that, by using systems with transmit and receive diversity, high gain can be achieved with very low complexity. It turns out that at BER = 10-4, the gain of 9 dB can be achieved for system using STTD transmit diversity only (without using any channel codes) and 2 dB gain can be achieved over channel coding systems using hard-decision decoding with much lower complexity. The most important conclusion is that, using soft-decision decoding systems enhanced with transmit diversity can provide very high coding gain; e.g., in convolutional coded system using soft-decision Viterbi decoder, the coding gain is 12 dB over uncoded system and 5 dB over hard-decision decoding in flat fading channel, while the coding gain is about 13 dB for turbo coded systems using soft-decision decoding based on SOVA algorithm with transmit diversity and the coding gain is 15 dB if the decoder is based on Log-MAP algorithm. In systems using transmit and receive diversity, the coding gain is much higher, e.g., for convolutional-coded systems, the coding gain is 20 dB, while for turbo-coded systems using SOVA and Log-MAP algorithms, the coding gain are a little more than 20 dB and 21 dB, respectively. View full abstract»

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  • A multiprocessor framework for rapid-prototyping and evaluation of soft transceivers

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (96 KB) |  | HTML iconHTML  

    Recent years have seen rapid evolution in the architectures being explored for realizing high-speed software-defined radios. There is, however, a distinct need for a low-cost programmable platform where algorithms for base-band transceivers can be rapidly prototyped and tested with real-world data, streaming in from diverse sources of telecommunication traffic. This paper explores an analytical method for laying out such a generic platform. It investigates the constraints involved in realizing such a platform, and the minimum functionality needed within the solution so as to provide adequate scalability to allow the implementation of a wide variety of communication algorithms. The paper concludes with a case study of a multi-channel communication system that has been successfully implemented on the proposed platform, highlighting the performance benchmarks it had to meet in order to prove suitable for the task of communication system evaluation. View full abstract»

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