Effect of fat-enriched diets on rabbit meat fatty acid composition

The effects of beef tallow-, soya and sunflower olein- and soya bean oil-enriched (3%) diets on the chemical and fatty acid composition of total, a polar and polar lipids of rabbit meat have been studied. No significant differences (P > 0.05) in the meat chemical composition were observed between groups. However, a large effect of the diet on the total and apolar lipid fatty acids was found, with C18:1 and C18:2 the most affected fatty acids. The influence of the diets on the fatty acids of the polar fraction was less marked. It is concluded that the enrichment of the rabbit diet with either soya and sunflower oleins or soya bean oil allows the production of rabbit meat with a higher unsaturation degree than is obtained by using conventional diets, which constitutes an important nutritional benefit to the human being.     

Generation of random variables for modelling VBR multimedia sources

The design and performance evaluation of multimedia systems require the availability of adequate models to mimic the statistical properties of the traffic generated by a multimedia source. In this paper the authors propose a very simple method for the generation of discretetime and discretestate autocorrelated random variables which can be used to model a traffic source by simulation. The probability distribution and autocorrelation sequence of the variables generated exactly match the corresponding experimental histograms of the source to be modelled when the experimental autocorrelation sequence is decreasing with downward convexity. In this paper an analytical demonstration of the method proposed is given and its use is illustrated by three telecommunications examples.     

Breakdown voltage of a plasma-filled gap

The letter reports a series of measurements on the breakdown voltage of a two-electrode gap immersed in an arc plasma.     

Reprocessing of thermally oxidized aluminum arsenide (AlAs) in epitaxial multilayers without delamination

Annealing or processing of AlAs that has been subjected to a wet thermal oxidation process can result in severe delamination of material at the oxidation front. This paper reports a procedure for preventing this delamination and presents a possible cause for the delamination.     

A Competitive Mean-Squared Error Approach to Beamforming

We treat the problem of beamforming for signal estimation where the goal is to estimate a signal amplitude from a set of array observations. Conventional beamforming methods typically aim at maximizing the signal-to-interference-plus-noise ratio (SINR). However, this does not guarantee a small mean-squared error (MSE), so that on average the resulting signal estimate can be far from the true signal. Here, we consider strategies that attempt to minimize the MSE between the estimated and unknown signal waveforms. The methods we suggest all maximize the SINR but at the same time are designed to have good MSE performance. Since the MSE depends on the signal power, which is unknown, we develop competitive beamforming approaches that minimize a robust MSE measure. Two design strategies are proposed: minimax MSE and minimax regret. We demonstrate through numerical examples that the suggested minimax beamformers can outperform several existing standard and robust methods, over a wide range of signal-to-noise ratio (SNR) values. Finally, we apply our techniques to subband beamforming and illustrate their advantage in estimating a wideband signal.     

Physical layer orthogonal frequency‐division multiplexing acquisition and timing synchronization security

Orthogonal frequency‐division multiplexing (OFDM) has become the manifest modulation choice for 4G standards. Timing acquisition and carrier frequency offset synchronization are prerequisite to OFDM demodulation and must be performed often. Most of the OFDM methods for synchronization were not designed with security in mind. In particular, we analyze the performance of a maximum likelihood synchronization estimator against highly correlated jamming attacks. We present a series of attacks against OFDM timing acquisition: preamble whitening, the false preamble attack, preamble warping, and preamble nulling.The performance of OFDM synchronization turns out to be very poor against these attacks, and a number of mitigation strategies and security improvements are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Extreme Two‐Phase Cooling from Laser‐Etched Diamond and Conformal,Template‐Fabricated Microporous Copper

This paper reports the first integration of laser‐etched polycrystalline diamond microchannels with template‐fabricated microporous copper for extreme convective boiling in a composite heat sink for power electronics and energy conversion. Diamond offers the highest thermal conductivity near room temperature, and enables aggressive heat spreading along triangular channel walls with 1:1 aspect ratio. Conformally coated porous copper with thickness 25 µm and 5 µm pore size optimizes fluid and heat transport for convective boiling within the diamond channels. Data reported here include 1280 W cm^?2 of heat removal from 0.7 cm² surface area with temperature rise beyond fluid saturation less than 21 K, corresponding to 6.3 × 10⁵ W m^?2 K^?1. This heat sink has the potential to dissipate much larger localized heat loads with small temperature nonuniformity (5 kW cm^?2 over 200 µm × 200 µm with <3 K temperature difference). A microfluidic manifold assures uniform distribution of liquid over the heat sink surface with negligible pumping power requirements (e.g., <1.4 × 10^?4 of the thermal power dissipated). This breakthrough integration of functional materials and the resulting experimental data set a very high bar for microfluidic heat removal.     

ELECTRON GUN FOR LARGE ORBIT GYROTRON (LOG) WITH DECREASED INFLUENCE OF CATHODE PLASMA ON ELECTRON BEAM PROPERTIES

High power Large Orbit Gyrotron (LOG) [1] is now under development at FIR FU. First version of this device was recently manufactured and then assembled with power supply ETIGO-IV [2]. Results of preliminary tests of electron-optic system are presented. The conditions when stable flat form of current pulse realized are discussed. Analytical estimations of cathode-anode distance to achieve small influence of cathode plasma during high voltage (HV) pulse are performed. Two new electron gun versions with decreased influence of the cathode plasma on its impedance and pulse form are suggested and optimized. New optimal magnetic field distributions are found. First gun has quiasi-flat cathode configuration near the anode diaphragm and provides operating current about 60 A. Second one uses blade cathode with operating current about 30 A. Beam quality for both guns is suitable for LOG operation.     

INFLUENCE OF MAGNETIC FIELD INHOMOGENEITY ON OPERATION OF THE THz GYROTRON WITH A PULSE MAGNET

Influence of magnetic field tapering on operation of a gyrotron working in the TE _4,12 mode at the second harmonic frequency 1013.67 GHz is investigated. It is found that the existing inhomogeneity of the magnetic field of the order of 0.25%–0.50% in the cavity allows one to achieve higher efficiencies. It improves also mode competition scenario by suppressing oscillations of the two parasitic TE _3,6 ⁺ and TE _5,5 ^? modes at the fundamental frequencies 513.35 GHz and 503.64 GHz, respectively.     

C49 defect influence on the C49–C54 transition

The C49–C54 transformation has been studied in TiSi₂ thin films having different concentration of defects. The defect concentration in the C49 phase has been varied using different thermal processes in the 460–540 °C temperature range; in fact, the defect concentration decreases with increasing the temperature and/or the duration of the thermal process as attested by the large variation of the silicide residual resistivity at 4 K. The kinetics of the transformation at 650 °C has been followed by in situ resistivity measurements and, for each sample, the transition time decreases as the defect concentration in the metastable phase decreases.