Improved determination of Q-factor and resonant frequency by a quadratic curve-fitting method

The Q-factor and peak frequency of resonant phenomena give useful information about the propagation and storage of energy in an electronic system and therefore its electromagnetic compatibility performance. However, the calculation of Q by linear interpolation of a discrete frequency response to obtain the half-power bandwidth can give inaccurate results, particularly if the data are noisy or the frequency resolution is low. We describe a more accurate method that makes use of the Lorentzian shape of the resonant peaks and involves fitting a second-order polynomial to the reciprocal power plotted against angular frequency. We demonstrate that this new method requires less than one quarter the number of frequency points as the linear method to give comparable accuracy in Q. The new method also gives comparable accuracy for signal-to-noise ratios that are approximately 8 dB greater. It is also more accurate for determination of peak frequency. Examples are given both from measured frequency responses and from simulated data obtained by the transmission line matrix method

Towards Informative Statistical Flow Inversion

This is the accepted version of 'Towards Informative Statistical Flow Inversion', archived originally at arXiv:0705.1939v1 [cs.NI] 14 May 2007.A problem which has recently attracted research attention is that of estimating the distribution of flow sizes in internet traffic. On high traffic links it is sometimes impossible to record every packet. Researchers have approached the problem of estimating flow lengths from sampled packet data in two separate ways. Firstly, different sampling methodologies can be tried to more accurately measure the desired system parameters. One such method is the sample-and-hold method where, if a packet is sampled, all subsequent packets in that flow are sampled. Secondly, statistical methods can be used to ``invert'' the sampled data and produce an estimate of flow lengths from a sample. In this paper we propose, implement and test two variants on the sample-and-hold method. In addition we show how the sample-and-hold method can be inverted to get an estimation of the genuine distribution of flow sizes. Experiments are carried out on real network traces to compare standard packet sampling with three variants of sample-and-hold. The methods are compared for their ability to reconstruct the genuine distribution of flow sizes in the traffic

(E,E)-N1,N2-Bis(2,6-di­fluoro­benzyl­idene)ethane-1,2-di­amine.

The asymmetric unit of the title compound, C16H12F4N2, comprises half of the potentially bidentate Schiff base ligand, with an inversion centre located at the mid-point of the central C—C bond. The crystal packing is stabilized by inter­molecular C—H⋯N and π–π inter­actions [centroid–centroid distance = 3.6793 (12) Å and inter­planar spacing = 3.4999 (7) Å]

They say coconut oil can aid weight loss, but can it really?

There has in recent years, been much media speculation and consumer interest in the beneficial satiating properties of consuming coconut oil and its potential to aid weight loss. However, the media has primarily cited studies using medium-chain triglycerides (MCT) oil. The current perspective looks at the research that is available on coconut oil. It examines if and how MCT-related research can be applied to coconut oil and if there is potential for coconut oil to aid weight loss. The current report indicates a lack of consistent evidence on the topic of coconut oil, satiety and weight loss. Given both the publicity and the increased consumption of coconut oil further research, particularly long-term clinical trials, in this area are warranted