16 Fuel science and technology (fundamental science, analysis, instrumentation)

equivalent. Timber was found to be the preferred option and steel the least desirable, with concrete in between, from an energy consumption and carbon emission point of view.

05/00484 Reliability theory and applications to risk analysis of power components and systems Foschi, R. O. International Journal o f Eleetrieal Power & Energy Systems, 2004, 26, (4), 249 256. The performance of engineering systems is not deterministic but rather controlled by the uncertainties in the variables affecting that performance. The evaluation of the probability of non-performance can be carried out implementing methods of reliability theory. This work presents a brief discussion of these methods and their applications to four problems relevant to risk analysis of power components and systems: transmission towers, pole distribution lines, the calibration of factored equations for performance-based design, and the reliability updating of existing structures under change of service conditions.

05/00485 Risks, vulnerability, sustainability and governance: a new landscape for critical infrastructures Gheorghe, A. V. International Journal o f Critical ln/?astruetures, 2004, 1,(1), 118 124. It is becoming clear that sustainable development is, sometimes, obstructed by new risks and vulnerabilities, such as SARS, HIV, terrorist attacks, etc. There is a need to outline and identify the current new trends, dependability and governance rules in order to properly model critical infrastructures for greater safety and operational performance. The present paper addresses the need for a comprehen- sive understanding of the management and evolution of critical infrastructures, when facing complex topology and various cultural environments.

05/00486 Robust coordinated design of excitation and TCSC-based stabilizers using genetic algorithms Abdel-Magid, Y. L. and Abido, M. A. Electric Power Systems Research, 2004, 69, (2-3), 129 141. Power system stability enhancement via robust coordinated design of a power system stabilizer (PSS) and a thyristor-controlled series capacitor (TCSC)-based stabilizer is thoroughly investigated in this paper. The coordinated design problem of robust excitation and TCSC- based controllers over a wide range of loading conditions and system configurations is formulated as an optimization problem with an eigenvalue-based objective function. The real-coded genetic algorithm (RCGA) is employed to search for optimal controller parameters. This study also presents a singular value decomposition (SVD)-based approach to assess and measure the controllability of the poorly damped electromechanical modes by different control inputs. The damping characteristics of the proposed control schemes are also evaluated in terms of the damping torque coefficient over a wide range of loading conditions. The proposed stabilizers were tested on a weakly connected power system. The damping torque coefficient analysis, non- linear simulation results, and eigenvalue analysis show the effectiveness and robustness of the proposed approach over a wide range of loading conditions.

05/00487 Selected considerations in utilizing Monte Carlo simulation in quantitative reliability evaluation of composite power systems Billinton, R. and Tang, X. Electrie Power Systems Research, 2004, 69, (2 3), 205-211. The reliability of the generation and major transmission facilities are important factors in modern electric energy supply. These facilities form what is known as the bulk electricity system. An evaluation of these systems involves the composite analysis of the generation and transmission facilities and can be conducted using analytical tech- niques, Monte Carlo simulation or a combination of these methods. This paper is focused on considerations that arise when utilizing Monte Carlo simulation in composite system adequacy evaluation. Two test systems are utilized to illustrate solution convergence characteristics, the effect of load curtailment priority orders, common mode failures and the inclusion of substations and switching stations in composite system analysis.

05/00488 Studies on equation of state of high temperature nuclear materials Joseph, M. et al. Annals g/'Nuclear Energy, 2004, 31, (I0), 1163-1175. Equations-of-state (EOS) of nuclear materials are needed for the reactor safety analysis. EOS for nuclear fuel materials such as oxides, nitrides, carbides, metal alloy and also for graphite-a moderator, are obtained based on principle of corresponding states (PCS). The total vapour pressures over the liquid region, calculated by the PCS method, are compared with experimental data obtained using an in-house developed laser-induced vaporization mass spectrometric facility for UO2, UC, ThO2 and graphite and are found to be in good agreement.

Vapour pressure of PuN is the highest and that of UC is the lowest for the range of temperatures involved in the event of a core disruptive accident. The vapour pressure of the mixed carbide fuel is very close to that of the alloy fuel.

05/00489 The study of active stack effect to enhance natural ventilation using wind tunnel and computational fluid dynamics (CFD) simulations Wong, N. H. and Heryanto, S. Energy and Buildings, 2004, 36, (7), 668- 678. This paper demonstrates the use of a combined methodology of wind tunnel experiments and CFD simulations to study the potential of using active stack to enhance natural ventilation in residential apartments in Singapore. Wind tunnel experiments were conducted to provide the boundary conditions for the subsequent CFD simulations. The results obtained from the wind tunnel experiments were also compared with that from CFD simulations to study the discrepancy between the two approaches. A total of 32 CFD simulations were conducted taking into consideration the design factors, which include stack sizes and locations, bedroom door operations, external wind effect and stack fan operation. The results were compared to a base case and the key design factors that significantly affect the ventilation performance were identified using factorial design analysis.

05/00490 Thermodynamic analyses of refrigerant mixtures using artificial neural networks Arcaklioglu, E. et al. Applied Energy, 2004, 78, (2), 219 230. The aim of this study is to make a contribution towards the efforts of reducing the use of CFCs by finding a drop-in replacement for pure refrigerants used in domestic and industrial appliances. The suggested solution is the use of HFC and HC based refrigerant mixtures. In this study, different possible ratios of these mixtures and their correspond- ing performances are investigated by using artificial neural networks (ANNs). The authors believe this dramatically reduces the times and efforts required to achieve these targets, coefficients of performances (COPs) and total irreversibilities (Tls) of refrigerants and their mixtures have been calculated for a vapour-compression refrigeration system with a liquid/suction line heat-exchanger. The constant cooling- load method is taken as a reference. The thermodynamic properties of refrigerants have been taken from REFPROP 6.01. To train the network, based on scaled conjugate gradient (SCO), Pola-Ribiere conjugate gradient (CGP), and Levenbcrg-Marquardt (LM) learning algorithms and a logistic sigmoid transfer function, various ratios of seven refrigerant mixtures of HFCs and HCs are used along with three CFCs (R12, R22, and R502). They were used as inputs while the COP and TI values, calculated as above, were the outputs. The network has yielded R 2 values of 0.9999 and maximum errors for training and test data were found to be 2 and 3%, respectively.

05/00491 Thermogravimetry as a tool to classify waste components to be used for energy generation Heikkinen, J. M. et al. Journal Of Analytical and Applied Pyrolysis, 2004, 71, (2), 883-900. In this paper, thermogravimetric analysis (TGA) is utilized to investigate pyrolysis of individual waste components and waste mixtures. Based on the measured weight loss characteristics, single waste components are divided into three classes: low stability organic, lignocellulosic and plastic materials. In order to calculate the composition of an unknown waste mixture, it is assumed that the thermal degradation curve of a mixture is obtained as a sum of the contributions of the corresponding single components. It is investigated whether this assumption holds for cellulosic, polymer and real waste mixtures. The paper demonstrates that the weighed sum method can provide an indication of the mixture composition.

05/00492 Three different genetic algorithm approaches to the estimation of residential exergy input/output values Ozturk, H. K. et al. Building and Environment, 2004, 39, (7), 807-816. This study develops residential exergy input/output estimation equations in order to better analyse exergy values and predict the future projections using genetic algorithm (GA) notion. GA EXnergy Input/Output Estimation Model (GAEXIEM/GAEXOEM) is used to estimate the future residential exergy input/output values based on the indicators of gross domestic product, population, import, export, house production, cement production and basic house appliances consump- tion. The model is applied to Turkey's residential sector, of which exergy input and output values were 861.06 and 77.32 PJ in 2002, respectively. The three different estimation models are proposed in quadratic forms. Developed models are validated with actual data, while future estimation of exergy values is projected for the years between 2003 and 2023. It may be concluded that all the models developed seem to be capable of predicting the residential-commercial exergy input/output values of Turkey as well as countries. This study is

64 Fuel and Energy Abstracts January 2005