Effects of plastic coating on K-alpha yield from ultra-short pulse

A study of the K-alpha radiation emitted from Ti foils irradiated with intense, similar to0.2 J, 67 fs, 800 nm laser pulses, scanning a range of intensities (similar to10(15)-10(18) W cm(-2)), is reported. The brightness of single-shot K-alpha line emission from the front of the targets is recorded. The yield from bare titanium (Ti) is compared to that from plastic (parylene-E) coated Ti. It is demonstrated that, for a defocused beam, a thin layer of plastic increases the yield.

Photodiodes array as potential diagnostic for measuring short bursts of K-alpha radiation from Ti targets irradiated with 45 fs laser pulses

We report on a study comparing absolute K-alpha yield from Ti foils measured with a calibrated system of an X-ray CCD coupled to a curved LiF Von-Hamos crystal spectrometer to the difference in the signals measured simultaneously with two similar photodiodes fitted with two different filters. Our data indicate that a combination of photodiodes with different filters could be developed into an alternative and inexpensive diagnostic for monitoring single shot pulsed emission in a narrow band of X-ray region.

A k-round Elimination Contention Scheme for WLANs

currently in press. This is the first published attempt to engineer QoS into a contention-based MAC layer protocol. The work was based on a cross-layer approach to providing programmability into wireless LANs. The work arose from an EPSRC grant in the "programmable networks" call, with Philips / STM research in Italy (Dr Melpignano). Subsequent follow-on includes the formation of a spin-out company (TOM) based on the idea.

Simultaneous feature selection and feature weighting using Hybrid Tabu Search/K-nearest neighbor classifier

Feature selection and feature weighting are useful techniques for improving the classification accuracy of K-nearest-neighbor (K-NN) rule. The term feature selection refers to algorithms that select the best subset of the input feature set. In feature weighting, each feature is multiplied by a weight value proportional to the ability of the feature to distinguish pattern classes. In this paper, a novel hybrid approach is proposed for simultaneous feature selection and feature weighting of K-NN rule based on Tabu Search (TS) heuristic. The proposed TS heuristic in combination with K-NN classifier is compared with several classifiers on various available data sets. The results have indicated a significant improvement in the performance in classification accuracy. The proposed TS heuristic is also compared with various feature selection algorithms. Experiments performed revealed that the proposed hybrid TS heuristic is superior to both simple TS and sequential search algorithms. We also present results for the classification of prostate cancer using multispectral images, an important problem in biomedicine.

Scale-length optimising of short pulse Cu K-alpha laser plasma sources

The authors present experimental results showing how the use of a high contrast femtosecond laser system allows better optimization of K emission from a Cu target. The shorter scale-length preformed plasma is better optimized for resonance absorption of the laser light when the laser is moved away from best focus. The experimental data show a central peak of K emission at tight focus with strong secondary peaks at large offset. The use of these secondary peaks results in a much reduced hard x-ray background and should lead to shorter K pulses than at tight focus.

Viscosity of binary mixtures of cycloalkane with cycloalkane, alkane and aromatic hydrocarbon at 303.15 K

The viscosity ? for eighteen binary mixtures cyclopentane + cyclohexane and + cyclooctane; cyclohexane + cycloheptane, + cyclooctane, + methylcyclohexane, + n-hexane, + n-heptane, + n-octane, + i-octane, + benzene, + toluene, + ethylbenzene, + p-xylene, and + propylbenzene; methylcyclohexane + n-hexane, + i-octane, and + benzene; and cyclooctane + benzene have been reported at 303.15 K over the entire range of composition. The viscosity deviations ?? and excess Gibbs energy of activation ?G*E of viscous flow based on Eyring's theory have been calculated. The effects of molecular sizes and shapes of the component molecules and of interaction energy in the mixture have been discussed. The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind, McLaughlin and Ubbelohde, Tamura and Kurata, Katti and Chaudhri, McAllister, Heric and Brewer, and of Auslaender.

Speeds of sound and isentropic compressibilities of binary mixtures containing trialkylamines with alkanes and mono-alkylamines at 303.15 and 313.15 K

Isentropic compressibilities ?S, and excess isentropic compressibilities ?SE have been determined from measurements of speeds of sound u and densities ? of 14 binary mixtures of triethylamine (TEA) and tri-n-butylamine (TBA) with n-hexane, n-octane, iso-octane, n-propylamine, n-butylamine, n-hexylamine and n-octylamine. The relative magnitude and sign of ?SE have been interpreted in terms of molecular interactions and interstitial accommodation. The values of ?SE for TEA + alkane are positive while for TBA + alkane are negative. The values of ?SE for TEA + primary amine become progressively less positive and eventually to negative with the increase in chain length of alkylamine. In case of TBA + primary amine, the values of ?SE increase from n-propylamine to n-butylamine, and then decrease with chain length of primary amine. The experimental speeds of sound u have been analyzed in terms of collision factor theory, free length theory and Prigogine–Flory–Patterson statistical theory of solutions.

Acoustic, volumetric, compressibility and refractivity properties and Flory’s reduction parameters of some homologous series of alkyl alkanoates from 298.15 to 333.15 K

The speeds of sound u in, densities ? and refractive indices nD of some homologous series, such as n-alkyl ethanoates, n-alkyl propionates, methyl alkanoates, ethyl alkanoates, dialkyl malonates, and alkyl haloalkanoates, were measured in the temperature range from 298.15 to 333.15 K. Molar volume V, isentropic and isothermal compressibilities ?S and ?T, molar refraction Rm, Eykman’s constant Cm, molecular radius r, Rao’s molar function R, thermal expansion coefficient a, thermal pressure coefficient ?, and Flory’s characteristic parameters image, P*, V*, and T* have been calculated from the measured experimental data. Applicability of Rao theory and Flory–Patterson–Pandey (FPP) theory have been examined and discussed for these alkanoates.

Speeds of sound, isentropic compressibilities, and excess molar volumes of cycloalkanes, alkanes and aromatic hydrocarbons at 303.15 K. II. Results for cycloalkanes+aromatic hydrocarbons

The speeds of sound u, isentropic compressibilities ?S, molar sound functions R, excess isentropic compressibilities ?SE and excess molar volumes VE for eight binary mixtures of cyclopentane, cyclohexane, cyclooctane and methylcyclohexane with benzene and of cyclohexane with toluene, ethyl benzene, p-xylene and propyl benzene at 303.15 K are reported. The effects of molecular sizes and shapes of the component molecules and of interaction energy in the mixture have been discussed. The Prigogine–Flory–Patterson theory has been applied to analyze the present binary mixtures along with the mixtures of cis- and trans-decalins with benzene and toluene taken from the literature.