Utilization of the Yellow Component of a Copper-Vapor Laser for Extending the Tuning Range of a Rhodamine 6G Dye Laser by Use of an Additional Dye in a Novel Coupled Resonator Scheme

We demonstrate the use of both 510.6- and 578.2-nm components and the extension of the tuning range of a Rhodamine 6G dye laser in a novel coupled resonator scheme. Rhodamine 6G is pumped by 510.6-nm light in one resonator and Sulforhodamine B is pumped by 578.2 nm in the other. The spectral tuning range of 564-609 nm of the Rhodamine 6G laser is extended up to 640 nm. A two-mirror arrangement ensures continuous tuning across the spectral ranges of the two dyes by rotation of a single plane mirror.     

An expert system based algorithm for short term load forecast

Existing studies on 1-24 hr load forecasting algorithms are reviewed, and an expert-system-based algorithm is presented as an alternative. The logical and syntactical relationships between weather and load as well as the prevailing daily load shapes have been examined to develop the rules for this approach. Two separate, but similar, algorithms have been developed to provide 1-6 hr and 24 hr forecasts. These forecasts have been compared with observed hourly load data for a Virginia electric utility for all seasons of the year. The 1 hr and 6 hr forecast errors (absolute average) ranged from 0.869% to 1.218% and from 2.437% to 3.48% respectively. The 24 hour forecast errors (absolute average) ranged from 2.429% to 3.300%     

Natural actor-critic algorithms

We present four new reinforcement learning algorithms based on actor-critic, natural-gradient and function-approximation ideas, and we provide their convergence proofs. Actor-critic reinforcement learning methods are online approximations to policy iteration in which the value-function parameters are estimated using temporal difference learning and the policy parameters are updated by stochastic gradient descent. Methods based on policy gradients in this way are of special interest because of their compatibility with function-approximation methods, which are needed to handle large or infinite state spaces. The use of temporal difference learning in this way is of special interest because in many applications it dramatically reduces the variance of the gradient estimates. The use of the natural gradient is of interest because it can produce better conditioned parameterizations and has been shown to further reduce variance in some cases. Our results extend prior two-timescale convergence results for actor-critic methods by Konda and Tsitsiklis by using temporal difference learning in the actor and by incorporating natural gradients. Our results extend prior empirical studies of natural actor-critic methods by Peters, Vijayakumar and Schaal by providing the first convergence proofs and the first fully incremental algorithms.     

Similarity measures in formal concept analysis

Formal concept analysis (FCA) has been applied successively in diverse fields such as data mining, conceptual modeling, social networks, software engineering, and the semantic web. One shortcoming of FCA, however, is the large number of concepts that typically arise in dense datasets hindering typical tasks such as rule generation and visualization. To overcome this shortcoming, it is important to develop formalisms and methods to segment, categorize and cluster formal concepts. The first step in achieving these aims is to define suitable similarity and dissimilarity measures of formal concepts. In this paper we propose three similarity measures based on existent set-based measures in addition to developing the completely novel zeros-induced measure. Moreover, we formally prove that all the measures proposed are indeed similarity measures and investigate the computational complexity of computing them. Finally, an extensive empirical evaluation on real-world data is presented in which the utility and character of each similarity measure is tested and evaluated.     

An analytic solution for the space–time fractional advection–dispersion equation using the optimal homotopy asymptotic method

We present an analytic algorithm to solve the space–time fractional advection–dispersion equation (FADE) based on the optimal homotopy asymptotic method (OHAM), which has the advantage of controlling the region and rate of convergence of the solution series via several auxiliary parameters over the traditional homotopy analysis method (HAM) having only one auxiliary parameter. Furthermore, our proposed algorithm gives better results compared to the Adomian decomposition method (ADM) and the homotopy perturbation method (HPM) in the sense that fewer iterations are required to get a sufficiently accurate solution and the solution has a greater radius of convergence. We find that the iterations obtained by the proposed method converge to the numerical/exact solution of the ADE as the fractional orders $\alpha ,\beta ,\gamma$ tend to their integral values. Numerical examples are given to illustrate the proposed algorithm. The figures and tables show the superiority of the OHAM over the HAM.     

Effect of Talc on Properties of Corn Starch Extrudates

Commercially available 0, 25, 50 and 70% amylose corn starches were extruded with up to 5% talc {(OH)₂Mg₃(Si₂O₅)₂} in a single screw Brabender laboratory extruder at 18% moisture content, 140°C barrel temperature, and 140rpm screw speed. Expansion ratio, unit density, percentages of closed and open pores, porosity and molecular degradation of extruded starches were measured. Addition of talc resulted in decreases in expansion ratio, unit density and percentage of open pores, and in increases in percentage of closed pores and porosity of extrudates. The extrudates became smaller with a greater number of round and uniformly sized cells with added talc. Gel permeation chromatographic fractionation of extrudates showed extensive degradation of fraction I with increasing talc concentrations. The talc appeared to have provided nucleation sites for water vaporization as the material exited the die of the extruder.     

Effects of Hydrogen-Dilution on Opto-Structural Properties of Hot-wire CVD Grown a-Si:H/nc-Si:H Multilayer for Photovoltaics

The multilayered thin film structure of amorphous silicon (a-Si:H) and nanocrystalline silicon (nc-Si:H) provides the possibility of bandgap tuning for fabrication of multijunction solar cells. This paper communicates a detailed analysis of optical and structural properties of a-Si:H/nc-Si:H multilayer thin films by hot-wire chemical vapor deposition at low hydrogen (H₂) and silane (SiH₄) flow rates. A set of multilayer films with 25 bilayers of a-Si:H/nc-Si:H are prepared using different hydrogen-dilution of SiH₄ in the alternating nc-Si:H layers. The first and the second order Raman scattering studies reveal the presence of mixed phases of silicon in the nc-Si:H layers. Raman and XRD investigation of the films confirm the presence of different sizes of the silicon nanocrystals. The optical spectroscopic analysis instead of FTIR analysis of multilayer films is utilized uniquely to determine the hydrogen content in the a-Si:H/nc-Si:H multilayers and is related to the amorphous phase of the films. No significant change in hydrogen content is observed and the amorphous phase is found to decrease with increase in hydrogen dilution. Further, no quantum size effect (QSE) was observed due to the large growth time of nc-Si:H layers. Thus the experimental result shows that the bandgap of multilayer films decreases due to reduction in amorphous silicon phase, ineffective QSE and relative loss of hydrogen content.

     

Inhibition of aflatoxin production inAspergillus flavus infected cotton bolls after treatment with neem (Azadirachta indica) leaf extracts

In separate treatments, a spore suspension ofA. flavus (control), an aqueous leaf extract of the subtropical neem tree plus a spore suspension ofA. flavus, or an aqueous neem leaf extract followed by anA. flavus spore suspension were injected 48 hr later onto the surfaces of locks of developing cotton bolls (30-day post anthesis). Thirteen days after the treatments, the seeds from the locules were harvested and both fungal growth and aflatoxin production were determined. Fungal growth was unaffected by the treatments but the seeds from locules receiving both neem leaf extracts andA. flavus simultaneously exhibited 16% inhibition of aflatoxin production, while the seeds in locules receivingA. flavus spores 48 hr after neem extract was added exhibited >98% inhibition in aflatoxin production. Neem leaf extracts contain an aflatoxin inhibiting factor, however, the neem leaf extract may need to translocate from the fibrous locule surface to the seed, prior to the fungal inoculation, for maximal effect.     

Optical properties of Se1−x Sb x thin films (0<x<0.5)

The energy gap (E _g) of approximately 100 nm thick films of the Se_1–x Sb _x system has been investigated using an optical transmission method. E _g is found to decrease linearly with increasing Sb concentration in Se_1–x Sb _x films. No anomalous behaviour in E _g is observed at x = 0.4 as reported earlier by Wood et al.     

Semi-dry pressed tiles from alluvial deposits of northern India

Drying problems are greatly reduced when shaping tiles in semi-dry conditions write J.B. Bhatnagar, R.B. Hajela and R.K. Goel, of the Research Institute at Roorkee, where testing shows that better dimensional accuracy and finish can be achieved compared to traditionally made clay tiles at plastic or stiff plastic consistency.