STABILITY ANALYSIS FOR TWO KINDS OF EQUATIONS IN TWO-SPECIES POPULATION DYNAMICS

In this paper we study the stability for equilibrium points of equations in two-population dynamics. We discuss two predator-prey-patch models. Model 1 is described by a differential equation. Model 2 is described by an integral differential equation. We obtain the conditions for the stability of their equilibrium points. The results show that the overall population stability despite local extinction is realizable.

Bayesian Reliability——Growth Analysis for Statistical of Diverse Population Based on Non-homogeneous Poisson Process

New armament systems are subjected to the method for dealing with multi-stage system reliability-growth statistical problems of diverse population in order to improve reliability before starting mass production. Aiming at the test process which is high expense and small sample-size in the development of complex system, the specific methods are studied on how to process the statistical information of Bayesian reliability growth regarding diverse populations. Firstly, according to the characteristics of reliability growth during product development, the Bayesian method is used to integrate the testing information of multi-stage and the order relations of distribution parameters. And then a Gamma-Beta prior distribution is proposed based on non-homogeneous Poisson process（NHPP） corresponding to the reliability growth process. The posterior distribution of reliability parameters is obtained regarding different stages of product, and the reliability parameters are evaluated based on the posterior distribution. Finally, Bayesian approach proposed in this paper for multi-stage reliability growth test is applied to the test process which is small sample-size in the astronautics filed. The results of a numerical example show that the presented model can make use of the diverse information synthetically, and pave the way for the application of the Bayesian model for multi-stage reliability growth test evaluation with small sample-size. The method is useful for evaluating multi-stage system reliability and making reliability growth plan rationally.

A Statistical Model for Predicting the Average Abundance Patterns of Heavier Elements in Metal-Poor Stars

We have collected nearly all the available observed data of the elements from Ba to Dy in halo and disk stars in the metallicity range -4.0 <[Fe/H]< 0.5. Based on the observed data of Ba and Eu, we evaluated the least-squares regressions of [Ba/Fe] on [Fe/H], and [Eu/H] on [Ba/H]. Assuming that the heavy elements (heavier than Ba) are produced by a combination of the main components of s- and r-processes in metal-poor stars, and choosing Ba and Eu as respective representative elements of the main s- and the main r-processes, a statistical model for predicting the Galactic chemical evolution of the heavy elements is presented. With this model, we calculate the mean abundance trends of the heavy elements La, Ce, Pr, Nd, Sm, and Dy with the metallicity. We compare our results with the observed data at various metallicities, showing that the predicted trends are in good agreement with the observed trends, at least for the metallicity range [Fe/H]≥ -2.5. Finally, we discuss our results and deduce some important information about the Galactic chemical evolution.

Enhanced data and methods for improving open and free global population grids:putting‘leaving noonebehind’into practice

Data on global population distribution are a strategic resource currently in high demand in an age of new Development Agendas that call for universal inclusiveness of people.However,quality,detail,and age of census data varies significantly by country and suffers from shortcomings that propagate to derived population grids and their applications.In this work,the improved capabilities of recent remote sensing-derived global settlement data to detect and mitigate major discrepancies with census data is explored.Open layers mapping builtup presence were used to revise census units deemed as‘unpopulated’and to harmonize population distribution along coastlines.Automated procedures to detect and mitigate these anomalies,while minimizing changes to census geometry,preserving the regional distribution of population,and the overall counts were developed,tested,and applied.The two procedures employed for the detection of deficiencies in global census data obtained high rates of true positives,after verification and validation.Results also show that the targeted anomalies were significantly mitigated and are encouraging for further uses of free and open geospatial data derived from remote sensing in complementing and improving conventional sources of fundamental population statistics.

Fundamental Frequency Statistics for Young Male Speakers of Mandarin

In forensic speaker comparison(FSC),it is essential not only to evaluate the similarity between two(or more)samples,but also the typicality of the features in the relevant population.For the typicality,it is necessary that the population statistics related to the phonetic parameters be available.This article presents the statistics for the fundamental frequency(F0)of 100 young Chinese male speakers producing both reading and spontaneous speech.Five descriptive statistics of long‑term F0,namely mean,median,mode,standard deviation(SD),and coefficient of variation(CV=SD/mean),are shown in histograms and scatter diagrams.Results show that the distributions of the five statistics are near normal.The findings are compared with the literature and discussed with respect to forensic phonetic implications.This article concludes that the results for the F0 statistics in the present study can be used in FSC casework as reference data on F0 for the young male Chinese population.

Material removal model of vertical impinging in fluid jet polishing

It is important for precise fabrication to research the material removal model of polishing. Simulation is done by computational fluid dynamics for fluid jet polishing （FJP）. Numerical research and theoretical description for abrasive particles discrete system are taken by population balance modeling method, and experiments are taken to research the removal profile by vertical fluid jet polishing （VFJP）. The results of experiment and sinmlation show that the removal profile of VFJP turns on a W-shaped profile. By analyzing the material removal mechanism of FJP that material is removed by particles impinging wear and wall movement erosion, the mathematical material removal model of VFJP is enduced. Comparing the mathematical material removal model with the experimental removal profile, it is found that the mathematical material removal model of VFJP is accurate.

Spatial and temporal distribution of Q-switched laser pulses in multimode regimes

The spatial and temporal distribution of Q-switched diode-pumped solid-state laser （DPSSL） pulses is investigated in multimode regimes. A theory model of spatial and temporal distribution of multimode Q- switched DPSSL pulses is established. The influences of position, initial inversion population density, and mode ratio on pulse width are studied. The results show that the pulse expands in the position wherein two or more mode intensities are equivalent, and the pulse building time difference of the modes are less than one mode pulse width. These results can be applied in pulse compression and mode composition.