Clustering properties of partly charged superfine particles in a light medium

This paper investigated average cluster sizes （ACS） and cluster size distributions （CSD） at different shear rates by Brownian dynamics in non-, bi-, and uni-polar systems with partly charged superfine particles, The investigation indicates that clusters in non- polar systems are the weakest and easiest to be damaged by increasing shear stresses; charged particles play important and different roles： in bi-polar system, it intends to strengthen clusters to some extent provided that the sign-like ions homogeneously arranged; in uni-polar system charged particles cracked the clusters into smaller ones, but the small clusters are strong to stand with larger shear stress. The relationship between ACS and shear rates follows power law with exponents in a range 0.18-0.28, these values are in a good agreement with experiment range but at the lower limit compared with other systems of non-metallic cluster particles.

Kinetics Investigation of Sintering of Nanometer Size Metal Clusters:A Molecular Dynamics Study

The sintering process of nanometer size gold clusters is investigated by using molecular dynamics simulation in the frame of embedded atomistic method. Several molecular dynamics simulation techniques are used to observe and describe the evolution of the sintering process. The energy distribution for single cluster is examined and the snapshots of sintering process of two clusters are recorded. The evolution of sintering is also described by plotting the mass center changes with time for each cluster. The variations of kinetic and potential energy during the process of sintering are monitored and measured to analyze the dominant mechanisms of sintering from the energy point of view.

Average cluster sizes and cluster size distributions of superfine nickel particles in light media

Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering properties in these systems were compared with those in non-polar systems. The results show that the ACSs in bi-polar systems are larger than those in the non-polar systems. In uni-polar systems the behavior of clustering property differs: at the lower ionic concentration (10%), repulsive force is not strong enough to break clusters, but may greatly weaken them. The clusters are eventually cracked into smaller ones only when concentration of uni-polar charged particles is large enough. In this work, the ionic concentration is 20%. The relationship between ACS and shear rates follows power law in a exponent range of 0.176-0.276. This range is in a good agreement with the range of experimental data, but it is biased towards the lower limit slightly.

Variations in epidemic distribution with some characteristic parameters

Considering the spread of an epidemic among a population of mobile agents that can get infected and maintain the infection for a period, we investigate the variation in the homogeneity of the distribution of the epidemic with the remaining time of infection % the velocity modulus of the agent v, and the infection rate a. We find that the distribution of the infected cluster size is always exponential. By analyzing the variation of the characteristic infected cluster size coefficient, we show that the inhomogeneity of epidemic distribution increases with an increase in τ for very low v, while it decreases with an increase in τ- for moderate v. The epidemic distribution also tends to a homogeneous state as both v and a increase.

Power analysis for stratified cluster randomisation trials with cluster size being the stratifying factor

Stratified cluster randomisation trial design is widely employed in biomedical research and cluster size has been frequently used as the stratifying factor.Conventional sample size calculation methods have assumed the cluster sizes to be constant within each stratum,which is rarely true in practice.Ignoring the random variability in cluster size leads to underestimated sample sizes and underpowered clinical trials.In this study,we proposed to directly incorporate the variability in cluster size(represented by coefficient of variability)into sample size calculation.This approach provides closed-form sample size formulas,and is flexible to accommodate arbitrary randomisation ratio and varying numbers of clusters across strata.Simulation study shows that the proposed approach achieves desired power and type I error over a wide spectrum of design configurations,including different distributions of cluster sizes.An application example is presented.

Size estimates of nobel gas clusters by Rayleigh scattering experiments

Noble gases (argon, krypton, and xenon) are puffed into vacuum through a nozzle to produce clusters for studying laser-cluster interactions. Good estimates of the average size of the argon, krypton and xenon clusters are made by carrying out a series of Rayleigh scattering experiments. In the experiments, we have found that the scattered signal intensity varied greatly with the opening area of the pulsed valve. A new method is put forward to choose the appropriate scattered signal and measure the size of Kr cluster.

Further geometric morphometric analysis on the genus Eysarcoris(Hemiptera:Pentatomidae) from China

Further geometric morphometric analysis of the genus Eysarcoris was done based on the former studies to classified the nine Eysarcoris species from China. In this study, six characters, such as forewing, hindwing, pygophore, head, pronotum and scutellum, were selected to investigate the shape variation of Eysarcoris. Significant divergence in the shapes of the six characters was observed among the species（p 〈 0.05）. For all methods, phenetic similarity based on the six characters agrees with the current status of the genus. The cluster analysis of eight species are consistent with the traditional morphological studies. CVA analysis also shows that the values of the six characters are not equal in taxonomy. Pygophore, forewing, hindwing and pronotum play more important roles in the classification.