School of Information Technology and Electrical Engineering Publications - UQ eSpace

Analysis of hexagonal array geometry for free-space optical interconnects with improved signal-to-noise ratio

2008-02-18T00:00:00Z

The effect of transmitter and receiver array configurations on the performance of free-space optical interconnects (FSOIs) was investigated. Experimentally measured, spectrally resolved, near-field images of vertical-cavity surface-emitting laser (VCSEL) transverse modes were used as extended sources in our simulation model and combined with laser relative intensity noise and the receiver noise to determine the optimal array geometry. Our results demonstrate the importance of stray-light cross talk in both square and hexagonal configurations. By changing the array lattice geometry from square to hexagonal, we obtained an overall optical signal-to-noise ratio improvement of 3 dB. We demonstrated that the optical signal-to-noise ratio is optimal for the hexagonal channel arrangement regardless of the transverse mode structure of the VCSEL beam. We also determined the VCSEL drive current required for the best performance of the FSOI system. (c) 2007 Optical Society of America.

Analysis of hot-carrier-induced degradation in MOSFET's by gate-to-drain and gate-to-substrate capacitance measurements

2008-06-06T00:00:00Z

Analysis of induction motor drive under abnormal voltage conditions

2011-03-08T00:00:00Z

Analysis of insulation characteristics of coconut oil as an alternative to the liquid insulation of power transformers

2010-03-08T00:00:00Z

This paper presents the experimental results of a study, which has been carried out to analyze the insulation characteristics of coconut oil in order to check the suitability as the liquid insulation in power transformers. In this study dielectric response measurements were carried out in Frequency domain at temperatures of 25 °C, 50 °C, 80 'C. In addition, results of mineral oil samples were taken for comparison. Further, Breakdown Voltage was also measured on samples. Based on the results, relative permittivity and conductivity values were obtained at room temperature (25 'C) and elevated temperatures. Finally, the activation energy values were calculated on each sample. The dielectric breakdown voltages of the five coconut oil samples were in the range of 9.3 kV to 18.4 kV, which should be above 50 kV according to the IEC60296 standard. Conductivity values of coconut oil at room temperature were in a range from 10-11 to 10- 12 S, which is considerably higher than that of new mineral oil. These results imply that further purification is required to bring coconut oil to the required standard to use as an insulating medium in transformers. Effort was done to identify the effect of temperature on dielectric response measurements of oil insulation system and correlation of it with the conductivity. The activation energy of five coconut oil samples was around 0.1, which is less than that of mineral oil, i.e. 0.4. This implies that the increase of conductivity with temperature is considerably low in coconut oil, when comparing with mineral oil.

Analysis of JSQ policy on soft real-time scheduling in cluster

Zhu, W. — 2008-06-06T00:00:00Z

Analysis of kernel effects on optimisation mismatch in cache reconfiguration

Shield, J. og Sutton, P. og Machanick, P. — 2008-04-10T00:00:00Z

Analysis of lensless free-space optical interconnects based on multi-transverse mode vertical-cavity-surface-emitting lasers

2008-06-10T00:00:00Z

The feasibility of lensless free-space optical interconnects (FSOI's) using Vertical-Cavity-Surface-Emitting Lasers (VCSEL's) is investigated. The signal-to-noise ratio (SNR) and interconnect capacity of FSOI's in the presence of higher order modes are analyzed. The dependence of the SNR on feature parameters of VCSEL and photodetector arrays and the dependence of the capacity on channel spacing are simulated. The results have shown that lensless FSOI's can be achieved in chip level applications and the presence of higher order modes will deteriorate their performance, Moreover, the maximum distance of interconnection and the effect of lateral misalignment are also investigated. (C) 1999 Elsevier Science B.V. All rights reserved.

Analysis of link break detection using HELLO messages

2011-10-28T00:00:00Z

HELLO messages are widely used for neighbor discovery in routing protocols for wireless multihop networks. In this paper, we provide mathematical and experimental proofs that the current strategy of declaring a link down based on observations that a specific number of HELLO messages are lost, is 110t a correct strategy. In our mathematical analysis, we characterized the error bursts over wireless links by extending the Gilbert bit error model, and validate our model using HELLO loss data from our wireless mesh testbed. Our analysis shows that error burst lengths follow a geometric distribution, i.e. the probability of additional losses in the burst does not depend on the observed losses. We propose an alternative link break detection strategy where a link break is declared when the observed mean error burst length for the link is longer than the mean route recovery time. Our testbed results show that running the AODV routing protocol with our proposed strategy yields better throughput and lower control message overhead, compared to the case where AODV relies on its default settings of declaring link breaks when two consecutive HELLO messages are lost.

Analysis of nanometer displacement measurement using the self-mixing technique based on VCSEL

2011-03-01T23:26:53Z

Analysis of Optical Channel Crosstalk for Free-Space Optical Interconnects in the Presence of Higher Order Transverse Modes

2006-02-21T00:00:00Z

We analyse the effect of crosstalk noise on the performance of free space optical interconnects (FSOIs). In addition to 'diffraction-caused' crosstalk, we consider the effect of 'stray-light' crosstalk noise which, to the best of our knowledge, has not been addressed previously. Simulations were performed on a microlens based FSOI system using the modal composition and beam profiles experimentally extracted from a commercial Vertical-Cavity Surface-Emitting Laser. We demonstrate that this crosstalk noise introduces significant degradation to interconnect performance, particularly for multi-transverse mode laser sources. A simple behavioural model is also developed which accurately approximates the crosstalk noise for a range of optical sources and interconnect configurations.

Analysis of phasic and tonic electromyographic signal characteristics: Electromyographic synthesis and comparison of novel morphological and linear-envelope approaches

2008-04-15T00:00:00Z

Analysis of RSS improved RFID estimation

2011-03-07T00:00:00Z

Signal strength (SS) based tag estimation significantly improves the accuracy and speed of RFID tag interrogation. In [1], SS estimation was applied to a Manchester based RFID system and a formula for the lower bound on number of tags was derived. This paper analytically extends this analysis to a comprehensive list of encoding formats including all those used in commercially available tags. The developed formulas are shown to be based on properties of the line encoding. Our analysis shows that Manchester is the most appropriate encoding scheme for the signal strength estimation method.

Analysis of small signal stability margins using genetic optimization

Dong, ZY og Makarov, YV og Hill, DJ — 2007-08-13T00:00:00Z

Power system small signal stability analysis aims to explore different small signal stability conditions and controls, namely: (1) exploring the power system security domains and boundaries in the space of power system parameters of interest, including load flow feasibility, saddle node and Hopf bifurcation ones; (2) finding the maximum and minimum damping conditions; and (3) determining control actions to provide and increase small signal stability. These problems are presented in this paper as different modifications of a general optimization to a minimum/maximum, depending on the initial guesses of variables and numerical methods used. In the considered problems, all the extreme points are of interest. Additionally, there are difficulties with finding the derivatives of the objective functions with respect to parameters. Numerical computations of derivatives in traditional optimization procedures are time consuming. In this paper, we propose a new black-box genetic optimization technique for comprehensive small signal stability analysis, which can effectively cope with highly nonlinear objective functions with multiple minima and maxima, and derivatives that can not be expressed analytically. The optimization result can then be used to provide such important information such as system optimal control decision making, assessment of the maximum network's transmission capacity, etc. (C) 1998 Elsevier Science S.A. All rights reserved.

Analysis of snore sounds by higher order statistics for the non-contact screening of sleep apnea

2010-04-24T00:00:00Z

Analysis of TCP parallelization over wireless links

Fu, Q. og Indulska, J. — 2007-08-23T00:00:00Z

Analysis of the effect of transverse modes on free-space optical interconnect performance

2007-08-15T07:26:41Z

Vertical-cavity surface-emitting lasers (VCSELs) and microlenses can be used to implement free space optical interconnects (FSOIs) which do not suffer from the bandwidth limitations inherent in metallic interconnects. A comprehensive link equation describing the effects of both optical and electrical noise is introduced. We have evaluated FSOI performance by examining the following metrics: the space-bandwidth product (SBP), describing the density of channels and aggregate bandwidth that can be achieved, and the carrier-to-noise ratio (CNR), which represents the relative strength of the carrier signal. The mode expansion method (MEM) was used to account for the primary cause of optical noise: laser beam diffraction. While the literature commonly assumes an ideal single-mode laser beam, we consider the experimentally determined multimodal structure of a VCSEL beam in our calculations. It was found that maximum achievable interconnect length and density for a given CNR was significantly reduced when the higher order transverse modes were present in Simulations. However, the Simulations demonstrate that free-space optical interconnects are still a suitable solution for the communications bottleneck, despite the adverse effects introduced by transverse modes.

Analysis of the error performance of adaptive array antennas for CDMA with noncoherent M-ary orthogonal modulation in Nakagami fading

Durrani, S. og Bialkowski, M. E. — 2007-08-15T00:00:00Z

This letter presents an analytical model for evaluating the Bit Error Rate (BER) of a Direct Sequence Code Division Multiple Access (DS-CDMA) system, with M-ary orthogonal modulation and noncoherent detection, employing an array antenna operating in a Nakagami fading environment. An expression of the Signal to Interference plus Noise Ratio (SINR) at the output of the receiver is derived, which allows the BER to be evaluated using a closed form expression. The analytical model is validated by comparing the obtained results with simulation results.

Analysis of the gate capacitance measurement technique and its application for the evaluation of hot-carrier degradation in submicrometer MOSFETs

Hsu, C. T. og Lau, M. M. og Yeow, Y. T. — 2007-08-14T00:00:00Z

The use of gate-to-drain capacitance (C-gd) measurement as a tool to characterize hot-carrier-induced charge centers in submicron n- and p-MOSFET's has been reviewed and demonstrated. By analyzing the change in C-gd measured at room and cryogenic temperature before and after high gate-to-drain transverse field (high field) and maximum substrate current (I-bmax) stress, it is concluded that the degradation was found to be mostly due to trapping of majority carriers and generation of interface states. These interface states were found to be acceptor states at top half of band gap for n-MOSFETs and donor states at bottom half of band gap for p-MOSFETs. In general, hot electrons are more likely to be trapped in gate oxide as compared to hot holes while the presence of hot holes generates more interface states. Also, we have demonstrated a new method for extracting the spatial distribution of oxide trapped charge, Q(ot), through gate-to-substrate capacitance (C-gb) measurement. This method is simple to implement and does not require additional information from simulation or detailed knowledge of the device's structure. (C) 2001 Elsevier Science Ltd. All rights reserved.

Analysis of the influence of transmission congestion on power market based on LMP-lossless model

2010-04-20T00:00:00Z

Analysis of the Variance Threshold of Kay's Weighted Linear Predictor Frequency Estimator

2004-02-03T00:00:00Z

A theoretical approximation for the variance of Kay's weighted linear predictor frequency estimator is derived. From this expression, an inequality describing the variance threshold of the estimator is found. The window weights are then optimised to improve the variance. Numerical simulations demonstrate that the variance approximations are valid for medium to high signal-to-noise rations or for large numbers of samples.

Analysis of time-varying digital filters

Donskoi, L. og Cherniakov, M. S. — 2008-06-06T00:00:00Z

Analysis of transient eddy currents in MRI using a cylindrical FDTD method

2007-08-15T00:00:00Z

Most magnetic resonance imaging (MRI) spatial encoding techniques employ low-frequency pulsed magnetic field gradients that undesirably induce multiexponentially decaying eddy currents in nearby conducting structures of the MRI system. The eddy currents degrade the switching performance of the gradient system, distort the MRI image, and introduce thermal loads in the cryostat vessel and superconducting MRI components. Heating of superconducting magnets due to induced eddy currents is particularly problematic as it offsets the superconducting operating point, which can cause a system quench. A numerical characterization of transient eddy current effects is vital for their compensation/control and further advancement of the MRI technology as a whole. However, transient eddy current calculations are particularly computationally intensive. In large-scale problems, such as gradient switching in MRI, conventional finite-element method (FEM)-based routines impose very large computational loads during generation/solving of the system equations. Therefore, other computational alternatives need to be explored. This paper outlines a three-dimensional finite-difference time-domain (FDTD) method in cylindrical coordinates for the modeling of low-frequency transient eddy currents in MRI, as an extension to the recently proposed time-harmonic scheme. The weakly coupled Maxwell's equations are adapted to the low-frequency regime by downscaling the speed of light constant, which permits the use of larger FDTD time steps while maintaining the validity of the Courant-Friedrich-Levy stability condition. The principal hypothesis of this work is that the modified FDTD routine can be employed to analyze pulsed-gradient-induced, transient eddy currents in superconducting MRI system models. The hypothesis is supported through a verification of the numerical scheme on a canonical problem and by analyzing undesired temporal eddy current effects such as the B-0-shift caused by actively shielded symmetric/asymmetric transverse x-gradient head and unshielded z-gradient whole-body coils operating in proximity to a superconducting MRI magnet.

Analysis of yearlong performance of differently tilted photovoltaic systems in Brisbane, Australia

2013-06-11T15:02:44Z

Analytical closed-form solutions for different configurations of parallel-coupled microstrip lines

Abbosh, Amin — 2009-09-03T00:00:00Z

A multilayer inphase power divider with an ultra wideband behaviour is presented. The proposed divider exploits broadside coupling via a multilayer microstrip/slot configuration. The design method utilised for the device is based on the conformal mapping techniques. The developed device has a compact size with an overall dimension of 20 mm×30 mm. The simulated and measured results show that the proposed device has equal power division between the two output ports with <0.2 dB amplitude imbalance between them, better than 10 dB return loss and isolation and <2° phase difference between the two output signals across the frequency band 3.1–10.6 GHz. [ABSTRACT FROM AUTHOR]

Analytical expression for the maximum ratio combiner (MRC) signal-to-noise ratio in correlated Rician fading channels due to antenna mutual coupling

Hui, H. T. og Zhang, T og Lu, Y — 2007-08-23T00:00:00Z

Analytical expressions for DG allocation in primary distribution networks

2010-09-16T13:27:13Z

This paper proposes analytical expressions for finding optimal size and power factor of four types of distributed generation (DG) units. DG units are sized to achieve the highest loss reduction in distribution networks. The proposed analytical expressions are based on an improvement to the method that was limited to DG type, which is capable of delivering real power only. Three other types, e.g., DG capable of delivering both real and reactive power, DG capable of delivering real power and absorbing reactive power, and DG capable of delivering reactive power only, can also be identified with their optimal size and location using the proposed method. The method has been tested in three test distribution systems with varying size and complexity and validated using exhaustive method. Results show that the proposed method requires less computation, but can lead optimal solution as verified by the exhaustive load flow method. © 2006 IEEE.

Analytical model for approximating node throughputs in wireless mesh networks

2013-04-03T17:07:35Z

This paper describes an analytical model and an associated algorithm for assessing the throughputs of each host in wireless mesh networks (WMNs). It provides a framework for studying WMNs, particularly when the performance and parameters in multiple protocol layers have to be jointly evaluated and optimized. From the point of the implementation, a simple recursive formula with N − 1 iterations is used to obtain the throughput performance of N node WMNs. The produced expressions offer insights into understanding the performance of the individual nodes without referring to a specific medium access control layer or physical layer technology. The model serves as a general tool for capturing the characteristics of the WMNs. Using the model, the complexity of cross-layer studies is reduced, thus allowing researchers to focus on the modelling of other associated layers. The paper explains the rationale behind the model and provides examples of scenarios for which it is suitable. It is validated using discrete event simulations in the OPNET network simulator.

Analytical Representation of the Relationship Between Generator Design and System Fault Behavior

McDonald, J. D. F. og Saha, Tapan K. — 2005-08-05T00:00:00Z

This paper presents the development and application of an analytical method for formalizing the dependence of the behavior of a large power system under fault conditions on the equivalent impedance presented by a single generator. After selecting an appropriate generator model, it is demonstrated that network-wide fault behavior can be expressed as a rational function of the equivalent impedance presented by a single generator under fault conditions. This representation simplifies the identification and depiction of constraints imposed by system configuration on the ability of a generator replacement or augmentation to affect fault behavior. The effectiveness of the proposed method is confirmed by considering the three-phase fault currents produced in a six-bus test system. In addition, the new analytical method is extended to obtain a numerical estimate of the maximum possible change in fault behavior that could result from a generator replacement or augmentation. Overall, the new approach aids in the evaluation of the suitability of generator modification or augmentation schemes.

Analytical solution for target location using bistatic multi-transmitter and multi-receiver techniques

2007-08-24T00:00:00Z

Analytical strategies for renewable distributed generation integration considering energy loss minimization

2013-01-23T14:45:05Z

This paper presents three alternative analytical expressions, including two new expressions, to determine the optimum sizes and operating strategy of distributed generation (DG) units considering power loss minimization and a methodology to identify the best location. These expressions can be easily adapted to consider the renewable DG units (i.e., biomass, wind and photovoltaic) for minimizing energy losses by considering time-varying demand and possible operating conditions of DG units. The results obtained on a 69-bus distribution test system demonstrate that the proposed approaches can be adequate to determine the location, size and power factor of DG unit for minimizing energy losses. The alternative expressions can be utilized depending on availability of required data and these produce similar outcomes.

Analytical tools to assess the voltage stability of induction-based distributed generators

2012-03-20T12:24:27Z

The installation of induction distributed generators should be preceded by a careful study in order to determine if the point of common coupling is suitable for transmission of the generated power, keeping acceptable power quality and system stability. In this sense, this paper presents a simple analytical formulation that allows a fast and comprehensive evaluation of the maximum power delivered by the induction generator, without losing voltage stability. Moreover, this formulation can be used to identify voltage stability issues that limit the generator output power. All the formulation is developed by using the equivalent circuit of squirrel-cage induction machine. Simulation results are used to validate the method, which enables the approach to be used as a guide to reduce the simulation efforts necessary to assess the maximum output power and voltage stability of induction generators.

Analytic solution of the classic probabilistic load flow problem on a full AC model

2012-03-01T12:30:21Z

Analyzing process models using graph reduction techniques

Sadiq, W. og Orlowska, M. E. — 2008-06-10T00:00:00Z

The foundation of a process model lies in its structural specifications. Using a generic process modeling language for workflows, we show how a structural specification may contain deadlock and lack of synchronization conflicts that could compromise the correct execution of workflows. In general, identification of such conflicts is a computationally complex problem and requires development of effective algorithms specific for the target modeling language. We present a visual verification approach and algorithm that employs a set of graph reduction rules to identify structural conflicts in process models for the given workflow modeling language. We also provide insights into the correctness and complexity of the reduction process. Finally, we show how the reduction algorithm may be used to count possible instance subgraphs of a correct process model. The main contribution of the paper is a new technique for satisfying well-defined correctness criteria in process models. © 2000 Published by Elsevier Science Ltd. All rights reserved.

An Analysis of MIMO Channel's Capacity and Its Application in 3G

2009-04-01T00:00:00Z

An Analysis on the Research Ethics Cases Managed by the Committee on Publication Ethics (COPE) Between 1997 and 2010

Foo, Jong Yong Abdiel og Wilson, Stephen James — 2013-01-06T00:44:28Z

An analytical approach for DG allocation in primary distribution network

2009-11-26T00:00:00Z

This paper proposes an analytical expression to calculate the optimal size and an effective methodology to identify the corresponding optimum location for DG placement for minimizing the total power losses in primary distribution systems. The analytical expression and the methodology are based on the exact loss formula. The effect of size and location of DG with respect to loss in the network is also examined in detail. The proposed methodology was tested and validated in three distribution test systems with varying size and complexity. Results obtained from the proposed methodology are compared with that of the exhaustive load flows and loss sensitivity method. Results show that the loss sensitivity factor based approach may not lead to the best placement for loss reduction.

An analytical approach to the design of quiet cylindrical asymmetric gradient coils in MRI

2008-02-18T00:00:00Z

We consider the design of asymmetric gradient coils in a conventional cylindrical bore magnetic resonance imaging system. The gradient coils are switched on and off during the scan, and are therefore subject to Lorentz forces that cause them to buckle during the switching process. This in turn creates a pressure wave within the coil, and that gives rise to acoustic noise. We present a simplified linearized model for the deflection of the coil due to electromagnetic forces, which is amenable to solution using analytical methods. Closed-form solutions for the coil deflection and the pressure pulse and noise level within the coil are obtained. These are used to design new coil winding patterns so as to reduce the acoustic noise. Sample results are shown both for unshielded and shielded gradient coils. Extensions of this model are indicated, although it is suggested that the advantages of the present closed-form solutions might then not be available, and fully numerical solutions may be needed instead. (C) 2007 Wiley Periodicals, Inc.

An applet for the teacher: Mathematics for the imagination

Graham, Alan og Duke, Roger — 2012-02-14T12:21:07Z

An Application Profile which combines DC and MPEG-7 for Simple Video Description

Hunter J. — 2008-06-20T00:00:00Z

This document describes a simple application profile which combines Dublin Core and MPEG-7 elements for generic video description.

An approach for validating BCL contract specifications

Governatori, Guido og Milosevic, Zoran — 2005-08-22T00:00:00Z

We continue the study, started in [5], on the formal relationships between a domain specific contract language (BCL) and the logic of violation (FCL) proposed in [6,7]. We discuss the use of logical methods for the representation and analysis of business contracts. The proposed analysis is based on the notions of normal and canonical forms of contracts expressed in FCL. Finally we present a mapping from FCL to BCL that can be used to provide an executable model of a formal representation of a contract.

An approach to control a photovoltaic generator to damp low frequency oscillations in an emerging distribution system

2011-08-25T11:02:49Z

Factors like diminishing fossil fuels and environmental concerns are driving the integration of locally available energy resources at a distribution level. As a result, a number of stability issues have become a concern for utilities at distribution systems. One of the important stability concerns is the small signal stability caused by electromechanical or other low frequency oscillations. The oscillations with lower values of frequency and damping may cause instabilities. In such cases, a suitable control methodology must be applied to ensure the stability of an emerging distribution system. In this paper, a methodology to control the power factor of photovoltaic generator (PV) is proposed for enhancement of system stability. The impact of PV power factor control on a low damped mode is assessed by using both eigenvalue sensitivity and time domain analysis. An appropriate signal for the proposed controller is identified by residue technique. The effectiveness of the controller is tested in IEEE 43 bus test distribution system with distributed generators. Results show that reactive power support from PV is better for damping of critical mode.

An approach to formal verification of free-flight separation

Eder, Sebastian og Smith, Graeme — 2011-03-17T00:00:00Z

This paper presents an approach to verifying complex free-flight algorithms. We give an abstract model that defines properties that a concrete implementation of a (distributed) free-flight algorithm has to maintain to guarantee conflict free movement of airplanes. We develop this model gradually by defining the emergent behavior of airplanes at a very abstract level and refine our definitions towards a more concrete model. In this process, we prove every refinement step to guarantee correctness of our approach.

An approach to ontology for institutional facts in the semantic web

Colomb, R. M. og Dampney, C. N. G. — 2007-08-15T00:00:00Z

Refinement in software engineering allows a specification to be developed in stages, with design decisions taken at earlier stages constraining the design at later stages. Refinement in complex data models is difficult due to lack of a way of defining constraints, which can be progressively maintained over increasingly detailed refinements. Category theory provides a way of stating wide scale constraints. These constraints lead to a set of design guidelines, which maintain the wide scale constraints under increasing detail. Previous methods of refinement are essentially local, and the proposed method does not interfere very much with these local methods. The result is particularly applicable to semantic web applications, where ontologies provide systems of more or less abstract constraints on systems, which must be implemented and therefore refined by participating systems. With the approach of this paper, the concept of committing to an ontology carries much more force. (c) 2005 Elsevier B.V. All rights reserved.

An approach to specifying software frameworks

2007-08-23T00:00:00Z

A framework is a reusable design that requires software components to function. To instantiate a framework, a software engineer must provide the software components required by the framework. To do this effectively, the framework-component interfaces must be specified so the software engineer knows what assumptions the framework makes about the components, and so the components can be verified against these assumptions. This paper presents an approach to specifying software frameworks. The approach involves the specification of the framework’s syntax, semantics, and the interfaces between the framework and its components. The approach is demonstrated with a simple case study.

An Architecture for Assembling Agents that Participate in Alternative Heterogeneous Auctions

2005-04-07T00:00:00Z

This paper addresses the issue of developing agents capable of participating in several potentially simultaneous auctions of different kinds (English, First-Price, Vickrey), with the goal of finding the best price for an item on behalf of their users. Specifically, a multi-agent architecture is proposed, in which a manager agent cooperates with several expert agents, each specialised in a specific kind of auction. The expert agents communicate their knowledge to the manager agent in the form of probability functions, capturing the likelihood that a bid of a given price may win an auction. Given a set of such functions, the manager agent builds a bidding plan that it executes in concert with the expert agents.

An array antenna with wideband beam steering capability employing spatial signal processing

Uthansakul, M. og Bialkowski, M E — 2007-08-23T00:00:00Z

An assessment of electrical load forecasting using artificial neural network

2012-03-22T22:21:42Z

The forecasting of electricity demand has become one of the major research fields in electrical engineering. The supply industry requires forecasts with lead times, which range from the short term (a few minutes, hours, or days ahead) to the long term (up to 20 years ahead). The major priority for an electrical power utility is to provide uninterrupted power supply to its customers. Long term peak load forecasting plays an important role in electrical power systems in terms of policy planning and budget allocation. This paper presents a peak load forecasting model using artificial neural networks (ANN). The approach in the paper is based on multi-layered back-propagation feed forward neural network. For annual forecasts, there should be 10 to 12 years of historical monthly data available for each electrical system or electrical buss. A case study is performed by using the proposed method of peak load data of a state electricity board of India which maintain high quality, reliable, historical data providing the best possible results. Model's quality is directly dependent upon data integrity.

An Asymmetric Protocol for Argumentation Games in Defeasible Logic

2008-03-30T07:59:14Z

Agent interactions where the agents hold conflicting goals could be modelled as adversarial argumentation games. In many real-life situations (e.g., criminal litigation, consumer legislation), due to ethical, moral or other principles governing interaction, the burden of proof, i.e., which party is to lose if the evidence is balanced [4], is a priori fixed to one of the parties. Analogously, when resolving disputes in a heterogeneous agent-system the unequal importance of different agents for carrying out the overall system goal need to be accounted for. In this paper we present an asymmetric protocol for an adversarial argumentation game in Defeasible Logic, suggesting Defeasible Logic as a general representation formalism for argumentation games modelling agent interactions.

An atlas-based electron density mapping method for magnetic resonance imaging (MRI)-alone treatment planning and adaptive MRI-based prostate radiation therapy

2012-06-04T07:25:31Z

An Attempt to Correlate Time and Frequency Domain Polarisation Measurements for the Insulation Diagnosis of Power Transformer

Saha, Tapan K. og Purkait, Prithwiraj — 2005-02-21T00:00:00Z

The insulation system of power transformers (oil and paper/pressboard) generally change their dielectric properties during the life of the transformer and dielectric measurements have therefore been applied to assess the quality or state of ageing of the system. Both time domain and frequency domain dielectric diagnosis techniques have recently gained popularity in providing information on the condition of transformer oil-paper insulation. The present paper aims at deriving a correlation between these two methods of diagnosis. Simulation results along with actual field test results have demonstrated a direct correlation between the time and frequency domain tools for insulation diagnosis.