Multi-objective optimal reactive power dispatch considering voltage stability in power systems using HFMOEA

This paper proposes a new hybrid fuzzy multi-objective evolutionary algorithm (HFMOEA) based approach for solving complex multi-objective, mixed integer nonlinear problems such as optimal reactive power dispatch considering voltage stability (ORPD-VS). In HFMOEA based optimization approach, the two parameters like crossover probability (P_C) and mutation probability (P_M) are varied dynamically through the output of a fuzzy logic controller. The fuzzy logic controller is designed on the basis of expert knowledge to enhance the overall stochastic search capability for generating better pareto-optimal solution. Two detailed case studies are presented: Firstly, the performance of HFMOEA is tested on five benchmark test problems such as ZDT1, ZDT2, ZDT3, ZDT4 and ZDT6 as suggested by Zitzler, Deb and Thiele; Secondly, HFMOEA is applied to multi-objective ORPD-VS problem. In both the case studies, the optimization results obtained from HFMOEA are analysed and compared with the same obtained from two versions of elitist non-dominated sorting genetic algorithms such as NSGA-II and MNSGA-II in terms of various performance metrics. The simulation results are promising and confirm the ability of HFMOEA for generating better pareto-optimal fronts with superior convergence and diversity.     

Evaluation of satellite-altimetry-derived river stage variation for the braided Brahmaputra River

In this study, river stage variation derived from satellite altimetry was used to assess the water level, monthly discharge, and annual water yield at six virtual gauging stations at the braided reaches of the Brahmaputra River. The braided reaches of the river dynamically change their planform, thalweg line, and aggradation or degradation period. Stage records derived from the Envisat satellite of the European Space Agency and Topex/Poseidon of NASA/CNES were used for the period 2002–2010. Spatial interpolation and datum correction were applied on altimetry-derived river stage records before analysis. A correlation and error analysis between the in situ and satellite-altimetry-derived stages was carried out for these stations for both monsoon and non-monsoon seasons. Yearly optical satellite images were used for qualitative assessment of temporal variations in aggradation/degradation phases at the gauging stations. Using the pseudo-rating curve, discharges at two virtual gauging stations were estimated. The results show that the altimetry-estimated discharges are of good agreement with observed discharge for the monsoon months (June–September) as compared with the non-monsoon months (October–May). In order to assess the annual water yield variability, yearly variation in annual water yield from the altimetry data was also estimated and compared to that observed. The estimated annual water yields were 90% accurate. Similarly, the long-term averaged monthly discharge series estimated from satellite altimetry closely follows the temporal trend of that of the observed series.     

Compensation for subpixel roughness effects in thermal infrared images

Emissivity spectra recovered from spectral radiance images may have lowered spectral contrast due to irradiance from nearby surface elements (‘cavity effect’). For analysis based only on photointerpretation or Reststrahlen band identification, it is not always necessary to account for cavity effects, but for full spectral analysis it may be desirable. We present an approach to compensate thermal infrared (TIR) images for cavity radiation. This approach is based on optical estimates of subpixel surface roughness and estimation of cavity contribution for different natural surfaces using a TIR radiosity model. It was tested using tripod-mounted Hyper-Cam (Telops, Inc., Quebec City, Canada) hyperspectral TIR images of natural targets from the Mojave Desert, California, USA, along with centimetre-scale digital elevation models of similar targets measured by ground lidar. For remote subpixel roughness estimation, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) nadir- and aft-looking (27.6°) near-infrared (NIR) brightness ratios, as well as synthetic aperture radar (SAR) images calibrated to roughness root mean square (RMS), were used. The TIR compensation approach is adaptable for different spectral resolutions, including hyperspectral.     

A new approach to study organic solar cell using Lambert W-function

Organic photovoltaic solar cells bear an important potential of development in the search for low-cost modules for the production of domestic electricity. One of the main differences between inorganic and organic solar cells is that photo-excitation in these materials does not automatically lead to the generation of free charge carriers, but to bind electron–hole pairs (exciton) with a binding energy of about 0.4 eV. Till now various numerical methods using approximations have been reported to study different aspects of organic solar cells. For the first time an accurate method using Lambert W-function is presented to study different parameters of organic solar cells.     

Biopolymer nanocomposite films reinforced with nanocellulose whiskers

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating from xylan-cellulose interactions. Qualitatively, the spectral data obtained for the NCW/xylan nanocomposite films indicated that the amount of xylan adsorbed to cellulose increases with the addition of NCW. In an attempt to quantify this effect, non-linear least-squared spectral line fitting was used to deconvolute the adsorbed xylan peak at -82 ppm. The peak intensity ratio of adsorbed xylan peak and xylan C1 peak, which represents the total amount of xylan increases suggesting that upon the addition of NCW, the amount of adsorbed xylan increases. In an effort to further infer the structure-property relationships associated with the observed strength and barrier properties, 1H NMR T2 relaxation experiments were also conducted to investigate the change in the nature of carbohydrate-water interactions as a result of NCW incorporation. Water adsorbed into the 50% nanocomposite film had significantly shorter relaxation times with respect to the control xylan/sorbitol and all other NCW/xylan nanocomposite films. Additionally, X-ray diffraction of the nanocomposite films showed increased levels of crystalline material in the nanocomposites due to NCW addition.     

On Scene Segmentation and Histograms-Based Curve Evolution

We consider curve evolution based on comparing distributions of features, and its applications for scene segmentation. In the first part, we promote using cross-bin metrics such as the Earth Mover's Distance (EMD), instead of standard bin-wise metrics as the Bhattacharyya or Kullback-Leibler metrics. To derive flow equations for minimizing functionals involving the EMD, we employ a tractable expression for calculating EMD between one-dimensional distributions. We then apply the derived flows to various examples of single image segmentation, and to scene analysis using video data. In the latter, we consider the problem of segmenting a scene to spatial regions in which different activities occur. We use a nonparametric local representation of the regions by considering multiple one-dimensional histograms of normalized spatiotemporal derivatives. We then obtain semisupervised segmentation of regions using the flows derived in the first part of the paper. Our results are demonstrated on challenging surveillance scenes, and compare favorably with state-of-the-art results using parametric representations by dynamic systems or mixtures of them.     

WebWork: METEOR2's Web-Based Workflow Management System

METEOR₂ workflow management systems consist of both (1) design/build-time and (2) run-time/enactment components for implementing workflow applications. An enactment system provides the command, communication and control for the individual tasks in the workflow. Tasks are the run-time instances of intra- or inter-enterprise applications. We are developing three implementations of the METEOR₂ model: WebWork, OrbWork and NeoWork. This paper discusses WebWork, an implementation relying solely on Web technology as the infrastructure for the enactment system. WebWork supports a distributed implementation with participation of multiple Web servers. It also supports automatic code generation of workflow applications from design specifications produced by a comprehensive graphical designer. WebWork has been developed as a complement of its more heavyweight counterparts (OrbWork and NeoWork), with the goal of providing ease of workflow application development, installation, use and maintenance. At the time of this writing, WebWork has been installed by several of the LSDIS Lab's industrial partners for testing, evaluation and building workflow applications.     

Revealing the relationships between alloy structure,composition and plastic deformation in a ternary alloy system by a combinatorial approach

A high-throughput approach based on magnetron co-sputtering of alloy libraries is employed to inves-tigate mechanical properties of crystalline and amorphous alloys in a ternary palladium(Pd)-tungsten(W)-silicon(Si)system with the aim to reveal the difference in plastic deformation response and extract the relevant structure-property relationships of the alloys in the system.It was found that in contrast to crystalline alloys,the amorphous ones,i.e.,metallic glasses,exhibited a much smaller fluctuation range in the plasticity parameters(Er2/H and Wp/Wt),indicating a significant difference in the plastic deformation mechanism controlling the mechanical properties for the respective alloys.We propose that the inho-mogeneous deformation of amorphous alloys localized in thin shear bands is responsible for the weaker compositional dependence of both plasticity parameters,while dislocation gliding in crystalline materials is significantly more dependent on the exact structure,thus resulting in a larger scattering range.Based on the representative efficient cluster packing model,a set of composition-dependent atomic structural models is proposed to figure out the structure-property relationships of amorphous alloys in Pd-W-Si alloy system.     

A method for determining the coefficient of friction in punch stretching of sheet metals

Punch-to-sheet friction plays an important role in determining the success or failure of many sheet metal stamping operations. Although some measurements of friction under the conditions of drawing have been made, this work is the first known attempt to experimentally determine the coefficient of friction for the case of stretching sheets over a hemispherical steel punch, without relying upon material properties. From measured plots of load vs punch displacement in a purely stretching operation, and using a condition of maximum normal pressure, an average value of the coefficient of friction is calculated for a number of materials under various conditions of lubrication. Ranking of different lubricants according to their coefficient of friction is given.