Software cost estimation based on modified <Emphasis Type="Italic">K</Emphasis>-Modes clustering Algorithm

Unsupervised technique like clustering may be used for software cost estimation in situations where parametric models are difficult to develop. This paper presents a software cost estimation model based on a modified K-Modes clustering algorithm. The aims of this paper are: first, the modified K-Modes clustering which is an enhancement over the simple K-Modes algorithm using a proper dissimilarity measure for mixed data types, is presented and second, the proposed K-Modes algorithm is applied for software cost estimation. We have compared our modified K-Modes algorithm with existing algorithms on different software cost estimation datasets, and results showed the effectiveness of our proposed algorithm.     

Design of fractional-order PIλDμ controllers with an improved differential evolution

Differential evolution (DE) has recently emerged as a simple yet very powerful technique for real parameter optimization. This article describes an application of DE to the design of fractional-order proportional–integral–derivative (FOPID) controllers involving fractional-order integrator and fractional-order differentiator. FOPID controllers’ parameters are composed of the proportionality constant, integral constant, derivative constant, derivative order and integral order, and its design is more complex than that of conventional integer-order proportional–integral–derivative (PID) controller. Here the controller synthesis is based on user-specified peak overshoot and rise time and has been formulated as a single objective optimization problem. In order to digitally realize the fractional-order closed-loop transfer function of the designed plant, Tustin operator-based continuous fraction expansion (CFE) scheme was used in this work. Several simulation examples as well as comparisons of DE with two other state-of-the-art optimization techniques (Particle Swarm Optimization and binary Genetic Algorithm) over the same problems demonstrate the superiority of the proposed approach especially for actuating fractional-order plants. The proposed technique may serve as an efficient alternative for the design of next-generation fractional-order controllers.     

Euler vector for search and retrieval of gray-tone images.

A new combinatorial characterization of a gray-tone image called Euler Vector is proposed. The Euler number of a binary image is a well-known topological feature, which remains invariant under translation, rotation, scaling, and rubber-sheet transformation of the image. The Euler vector comprises a 4-tuple, where each element is an integer representing the Euler number of the partial binary image formed by the gray-code representation of the four most significant bit planes of the gray-tone image. Computation of Euler vector requires only integer and Boolean operations. The Euler vector is experimentally observed to be robust against noise and compression. For efficient image indexing, storage and retrieval from an image database using this vector, a bucket searching technique based on a simple modification of Kd-tree, is employed successfully. The Euler vector can also be used to perform an efficient four-dimensional range query. The set of retrieved images are finally ranked on the basis of Mahalanobis distance measure. Experiments are performed on the COIL database and results are reported. The retrieval success can be improved significantly by augmentiong the Euler vector by a few additional simple shape features. Since Euler vector can be computed very fast, the proposed technique is likely to find many applications to content-based image retrieval.     

An efficient power delivering scheme for sensorless drive of Brushless DC motor

This paper presents a photovoltaic (PV) panel fed sensorless Brushless DC motor (BLDC) drive using Sheppard –Taylor (S–T) converter for load matching in order to make the system energy efficient. In this work, a detailed study on S–T converter is done as it helps to stabilize the fluctuating output voltage of standard PV panel. Hence, in this application model, we have considered S–T converter as a feed to the six switch three phase Brushless DC (BLDC) motor drive in which the rotor position is estimated using back electromotive force (EMF) detection technique. This work is developed and studied on MATLAB/Simulink platform as well as in real time implemented hardware. The simulation model has borrowed the motor parameters (viz. stator back-EMF, rotor RPM and max. output torque, etc.) and circuit components from the implemented hardware. Finally, a detailed study of the implemented S–T converter reveals a significant performance improvement over a conventional Buck–Boost converter for same PV panel. The output results show that the scheme described in this scope of work efficiently handles the DC power generated by solar cell using S–T converter as the rotor RPM offset is negligible in closed loop motor drive.

     

Converting ab initio energies to enthalpies of formation of free radicals. I. New atom equivalents for alkyl radicals

A simple method is presented to convert ab initio computed total energies to the standard enthalpy of formation (Δ_fH^o) of a large number of saturated alkyl radicals (especially those that are relatively highly branched), for which experimental data are scarcely available. For this purpose a new set of radical atom‐equivalents (AEQ) and their unique combinations were defined and the energy values of the latter assigned. The theory level and the basis set requirement for the quantum chemistry calculation of the molecular energy were found to be moderate. The Δ_fH^o predictions appear to be quite accurate with reference to limited available experimental data and are better than values calculated by the group‐additivity and the difference methods. The strategy provides an inexpensive way of harnessing the power of computational chemistry and combining it with the organization and insight from the group‐additivity method sans any empirical corrections. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Effect of test condition and stress free temperature on the electromigration failure of Cu dual damascene submicron interconnect line-via test structures

Atomic flux divergence (AFD) based finite element analyses have been performed to show the difference in the electromigration (EM) failure mechanisms at different test conditions for Cu dual damascene line-via test structures. A combined driving force approach adapted in the model consists of driving forces from electron-wind, stress-migration and thermo-migration. It is shown that the failure mechanisms depend on the test condition and the stress free temperature of the structure. As the failure time depends on the failure mechanisms, the life-time prediction from accelerated test would be inaccurate if the invariability of failure mechanisms is assumed. It is also found that the interconnect life-time can be improved by lowering the final annealing temperature of the structure.     

Theoretical modeling of condensation of steam outside different vertical geometries (tube, flat plates) in the presence of noncondensable gases like air and helium

Condensation of steam coming out from the coolant pipe during a loss of coolant accident (LOCA) plays a key role in removing heat from the primary containment of the advanced nuclear reactor (ANR). The presence of large mass fractions of air (W_air = 0.25-0.9) and a small mass fraction of helium (W_He = 0.017-0.083) reduces the overall heat transfer coefficient (HTC) substantially. The present work emphasizes on the issue that modeling the diffusion of water-vapor through the gas-liquid interface is the key to give good predictions in HTC. In this, condensation conductivity and effective diffusivity plays a key role. Therefore, modifications have been made in the derivation for calculation of condensation conductivity in the case of steam-air mixture and effective diffusivity (in the case of multicomponent mixture). The model validation has been done with the experimental data of Dehbi et al. [Dehbi, A.A., Golay, M.W., Kazimi, M.S., 1991. National Conference of Heat Transfer AIChE Symposium Series, pp. 19-28] and Anderson et al. [Anderson, M.H., Herranz, L.E., Corradini, M.L., 1998. Experimental analysis of heat transfer within the AP600 containment under postulated accident conditions. Nucl. Eng. Des. 185, 153-172] and other analytical models available in the literature [Herranz, L.E., Anderson, M.H., Corradini, M.H., 1998a. The effect of light gases in noncondensable mixtures on condensation heat transfer. Nucl. Eng. Des. 183, 133-150; Herranz, L.E., Anderson, M.H., Corradini, M.L., 1998b. A diffusion layer model for steam condensation within the AP600 containment. Nucl. Eng. Des. 185, 153-172; Peterson, P.F., Schrock, Y.E., Kageyama, T., 1993. Diffusion layer theory for turbulent vapor condensation with noncondensable gases. J. Heat Transf., 115; Dehbi, A.A., Golay, M.W., Kazimi, M.S., 1991. National Conference of Heat Transfer AIChE Symposium Series, pp. 19-28]. Since the validations of the results were found satisfactory, the datasets [Dehbi, A.A., Golay, M.W., Kazimi, M.S., 1991. National Conference of Heat Transfer AIChE Symposium Series, pp. 19-28; Anderson, M.H., Herranz, L.E., Corradini, M.L., 1998. Experimental analysis of heat transfer within the AP600 containment under postulated accident conditions. Nucl. Eng. Des. 185, 153-172] have been compared with a wide range of subcooling and the operating pressures. An extensive comparison has been reported and the results predicted by the present model were found to be satisfactory.     

The influence of consumers' environmental beliefs and attitudes on energy saving behaviours

With a heightened focus on the concept of sustainability in the past few decades, government, business and individuals have become increasingly aware of the need to reduce our environmental footprint. Consequently there has been much research on consumer environmental behaviour, and the beliefs, norms and attitudes that influence this behaviour. In this article we develop a conceptual framework of consumer environmental behaviour and its antecedents, and test hypotheses within the framework by means of a survey of green consumers. The results show that general environmental beliefs do influence norms on environmental actions and prices, but only norms on price are correlated with environmental attitudes; both intrinsic and extrinsic environmental drivers together with social norms and community influence are associated with environmental attitudes, but cost barriers may have a negative influence. It was also found that there was a strong association between environmental attitudes and energy saving behaviours but the latter was not in any way influenced by government policies or subsidies.     

Supercontinuum generation in a Bragg fiber：a novel proposal

Nonlinear optical effects such as self-phase modula-tion,four-wave mixing,cross-phase modulation,sti mula-ted Raman scattering,together with appropriate tempo-ral dispersion profileinan optical fiber couldsignificant-ly broaden ( >100 nm) the spectrumof a…