一个描述科技文献增长规律的新模型

一个描述科技文献增长规律的新模型韩冬梅（石油大学图书馆山东２５７０６２ＡｂｓｔｒａｃｔＩｎｔｈｉｓａｒｔｉｃｌｅ，ｔｈｅｓｃｉｅｎｔｉｆｉｃｌｉｔｅｒａｔｕｒｅｇｒｏｗｔｈｌａｗｉｓｓｔｕｄｉｅｄ．Ａｄｉｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎｉｓｂｕｉｌ...

胎儿生长的数学模型

根据孕 16～ 2 8周胎儿双顶径、头围、腹围及股骨长等的超声测量值拟合 Rossavik数学模型 [P=c(t) k+ s( t) ]建立胎儿个体生长曲线。结果显示 ,2 0例正常单胎的超声参数与 Rossavik模型的拟合效果好 ,孕 2 8～

B超测量值拟合数学模型监测胎儿个体生长的探讨

目的 探讨监测胎儿个体生长的方法。方法 根据孕 18～ 39周胎儿双顶径、头围、腹围及股骨长等的超声测量值拟合Rossavik数学模型 [P =c(t) k +s(t) ]建立胎儿个体生长曲线 (回归法和两点简化法 )。结果 2 0例正常单胎的超声参数与Rossavik模型的拟合效果好 (R2 :99.5 %～ 99.7% )。孕 33周和 39周胎儿各项参数的回归法及两点简化法预测值与实测值比较均无显著差异。前瞻性分析 30例胎儿各项参数的两点简化法预测值与实测值 ,亦无显著性差异。结论 根据孕 2

浅析我国的人口发展过程

本文利用Ｍａｌｔｈｕｓ生物总数增长定律以及Ｖｅｒｈｕｌｓｔ生物总数增长统计筹算律［１］［２］，对我国人口的发展情况进行检验、分析和予测．

胎儿器官发育规律模型的进一步探讨

应用兰州、新疆、河南、浙江和江西等地区的千余例正常胎儿内脏器官重量及外形长度测量数据，对依据生物体细胞增殖原理建立起来的胎儿器官发育规律的数学模型进行了参数辩识和曲线拟合，得到满意的结果。

Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials

In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switch devices of surge arresting materials, in general.

Containment effort reduction and regrowth patterns of the Covid-19 spreading

In all countries the political decisions aim to achieve an almost stable configuration with a small number of new infected individuals per day due to Covid-19.When such a condition is reached,the containment effort is usually reduced in favor of a gradual reopening of the social life and of the various economical sectors.However,in this new phase,the infection spread restarts and,moreover,possible mutations of the virus give rise to a large specific growth rate of the infected people.Therefore,a quantitative analysis of the regrowth pattern is very useful.We discuss a macroscopic approach which,on the basis of the collected data in the first lockdown,after few days from the beginning of the new phase,outlines different scenarios of the Covid-19 diffusion for longer time.The purpose of this paper is a demonstration-of-concept:one takes simple growth models,considers the available data and shows how the future trend of the spread can be obtained.The method applies a time dependent carrying capacity,analogously to many macroscopic growth laws in biology,economics and population dynamics.The illustrative cases of France,Italy and United Kingdom are analyzed.