Use Of Different Distributions Research Articles

Recommendations related to the Peak-current distributions in studies of lightning performance of transmission lines based on the range of critical currents associated with Backflashover

The impact of cumulative peak current distributions of first return stroke currents on the calculated lightning performance of transmission lines was addressed. The specific features of distributions obtained from measurements at instrument towers and of enlarged distributions including data of magnetic links, were analyzed. The result of their application to real transmission lines (of 138, 230, 345 and 500 kV and exhibiting different parameters) was determined, in terms of backflashover probability and rate. The use of different distributions resulted in great impact on the calculated performance. This impact depends overall on the range of critical currents, below 90 kA and above 100 kA, in which the behavior of the distributions is quite different. Based on the results, a set of recommendations were presented to support the user on the decision about the distribution to adopt, considering the specific features of the transmission line.

An improved mathematical prediction of the time evolution of the Covid-19 pandemic in Italy, with a Monte Carlo simulation and error analyses

We present an improved mathematical analysis of the time evolution of the Covid-19 pandemic in Italy and a statistical error analyses of its evolution, including a Monte Carlo simulation with a very large number of runs to evaluate the uncertainties in its evolution. A previous analysis was based on the assumption that the number of nasopharyngeal swabs would be constant. However, the number of daily swabs is now more than five times what it was when we did our previous analysis. Therefore, here we consider the time evolution of the ratio of the new daily cases to number of swabs, which is more representative of the evolution of the pandemic when the number of swabs is increasing or changing in time. We consider a number of possible distributions representing the evolution of the pandemic in Italy, and we test their prediction capability over a period of up to 6 weeks. The results show that a distribution of the type of Planck black body radiation law provides very good forecasting. The use of different distributions provides an independent possible estimate of the uncertainty. We then consider five possible trajectories for the number of daily swabs and we estimate the potential dates of a substantial reduction in the number of new daily cases. We then estimate the spread in a substantial reduction, below a certain threshold, of the daily cases per swab among the Italian regions. We finally perform a Monte Carlo simulation with 25,000 runs to evaluate a random uncertainty in the prediction of the date of a substantial reduction in the number of diagnosed daily cases per swab.

The Effects of Different Activity Distributions on Project Duration in PERT Networks

The original PERT technique assumes β distribution for the activity durations. The developments of the past decades have partly refuted this concept; and many different distributions have been introduced.In our research, various distributions (uniform, triangular, β) are applied in case of closed large-scale infrastructure projects.In this paper, the possible effects of these distributions on the project duration are investigated. It is shown that the use of different distributions with the same three-point estimation has a smaller effect on the project duration than a 10% difference in the values of the three-point estimation.

SOME OBSERVATIONS ON THE BEHAVIOR OF THE METHOD OF FUNDAMENTAL SOLUTIONS IN 3D ACOUSTIC PROBLEMS

The benchmark problem of room acoustics, consisting on the determination of the three-dimensional (3D) sound field generated by a point source placed within a closed acoustic space is here addressed by means of the Method of Fundamental Solutions (MFS). The focus of this paper is on the behavior of a MFS numerical frequency domain approach with regards to stability, accuracy, and efficiency. Strategies of improving stability and accuracy of the method such as the use of different distributions of collocation points and virtual sources or an singular value decomposition (SVD) solver are also analyzed. It has been found that these strategies allowed increasing accuracy and attaining stability. Comparison with a classical BEM model was also performed, and has shown that the MFS can reach excellent accuracy making use of smaller-sized equation systems.

Nuclear proton and neutron distributions in the detection of weak interacting massive particles

In the evaluation of weak interacting massive particles (WIMPs) detection rates, the WIMP-nucleus cross section is commonly described by using form factors extracted from charge distributions. In this work, we use different proton and neutron distributions taken from Hartree-Fock calculations. We study the effects of this choice on the total detection rates for six nuclei having different neutron excess, and taken from different regions of the nuclear chart. The use of different distributions for protons and neutrons becomes more important if isospin-dependent WIMP-nucleon interactions are considered. The need for distinct descriptions ofproton and neutron densities decreases with the lowering of detection energythresholds.

Distribution of Anisakis larvae, identified by genetic markers, and their use for stock characterization of demersal and pelagic fish from European waters: an update

In the present paper, recent results obtained on the use of different distributions observed in larval species of Anisakis, genetically identified by means of allozyme markers, for stock characterization of demersal (Merluccius merluccius), small (Trachurus trachurus) and large pelagic (Xiphias gladius) finfish species in European waters, are reviewed and discussed. Several species of Anisakis were identified in the three fish hosts: A. simplex (s.s.), A. physeteris, A. typica, A. ziphidarum, A. pegreffii, A. brevispiculata and A. paggiae. Canonical discriminant analysis performed on all the samples of the three fish species collected in areas comprising their geographical range, according to the different species of Anisakis identified, showed distinct fish populations in European waters. In all the three fish hosts, the pattern of distribution of Anisakis larvae allowed discrimination of Mediterranean stocks from Atlantic stocks. In the case of swordfish, the possible existence of a southern Atlantic stock separated from a northern one is also suggested. Congruence and discordance with the population genetic data inferred from allozyme markers on the same samples of the three fish species are also discussed.