Non-linear autoregressive time series with multivariate Gaussian mixtures as marginal distributions

A new form of non-linear autoregressive time series is proposed to model solar radiation data, by specifying joint marginal distributions at low lags to be multivariate Gaussian mixtures. The model is also a type of multiprocess dynamic linear model, but with the advantage that the likelihood has a closed form.     

长旋转椭球波函数本征值的精确计算

利用数值迭代技术给出了长旋转椭球波函数本征值的精确求解方法.当 c≤5时,本文的计算结果与文献[4]给出的数值吻合得很好,且具有更高的精度.给出的方法可以精确地求解 c<10时长旋转椭球波函数的本征值,计算精度达到10~(-14)。     

电磁导弹的两个工程问题

解决了电磁导弹的两个工程问题,即电磁导弹激励源时城波形的必要条件是波形函数必不连续;周期信号也能产生电磁导弹。为了应用,对实际能产生的激励信号在有限的距离之內呈现的电磁导弹效应进行了讨论。本文得到的结论对电磁导弹的实际应用有重要的价值。     

EM-FEL边带不稳定性的单粒子理论分析

利用单粒子理论分析了主频电磁波为常振幅缓变相移的电磁波泵自由电子激光(EM-FEL)的边带不稳定性,导出了色散方程,进行了详细地分析与讨论,并求出在几种特殊情况下的不稳定性区域与最大线性增长率,由此得出一些重要的结论。     

北京与上海经济辐射能力差异探析

本文指出北京在经济辐射能力方面远弱于上海,并分析了其原因以及两个城市经济辐射能力的发展趋势,最后就北京增强经济辐射能力提出一些建议。     

1982-2010年我国回族人口分布变动研究

本文根据2010年、2000年、1990年和1982年四次人口普查的数据,分析了1982-2010年28年间全国回族人口分布的整体趋势。结果显示：我国回族在流动中显示出越来越集中的趋势;回族人数在东南沿海和华东地区流动的趋势较为明显;东北地区回族人数多次呈现负增长。根据分析,笔者认为导致这一系列现象的主要原因在于地区经济辐射效应下,回族人群比较选择的结果。     

Assessment of Instructions on Protection Against Food Contaminated with Radiocesium in Japan in 2011

The Japan Ministry of Health, Labour and Welfare (MHLW) has published instructions for radiological protection against food after the Fukushima Daiichi nuclear power plant accident in 2011. Following the instructions, the export and consumption of food items identified as being contaminated were restricted for a certain period. We assessed the validity of the imposed restriction periods for two representative vegetables (spinach and cabbage) grown in Fukushima Prefecture from two perspectives: effectiveness for reducing dietary dose and economic efficiency. To assess effectiveness, we estimated the restriction period required to maintain consumers’ dose below the guidance dose levels. To assess economic efficiency, we estimated the restriction period that maximizes the net benefit to taxpayers. All estimated restriction periods were shorter than the actual restriction periods imposed on spinach and cabbage from Fukushima in 2011, which indicates that the food restriction effectively maintained consumers’ dietary dose below the guidance dose level, but in an economically inefficient manner. We also evaluated the response of the restriction period to the sample size for each weekly food safety test and the instructions for when to remove the restriction. Stringent MHLW instructions seemed to sufficiently reduce consumers’ health risk even when the sample size for the weekly food safety test was small, but tended to increase the economic cost to taxpayers.     

不接触电极法测量中发射信号的产生

本文介绍了不接触电极法测量的工作原理,测量中所需的发射信号的波形以及产生发射信号的电路。     

The impact of park trees on microclimate in urban areas

Trees in cities have an important positive effect on people’s lives. One such positive effect is the amelioration of microclimate. The aim of this research is to assess the correlation between parameters that affect the microclimate of parks during the summer. We measured air temperature, relative humidity and solar radiation in the sun and shade of the trees in urban parks in Thessaloniki, Greece. The results indicate that: the air (A) temperature reduction percentage (dTair%), air relative humidity increase (dTRh%), discontent index reduction percentage (DI%) (cooling effect) and solar radiation (L) percentage that passes through the trees’ foliage to their shade creates an exponential function of dA% = a.e-bL. These functions are also applicable to the limiting variation values of the parameters. If we use L = 0 (meaning Lightsh = 0, which is the case for an extremely dense tree), then the values that we expect from this particular parameter are the maximum possible. These maximum values are a characteristic feature of the parameter variation for this particular research area. These maximum values for the trees in the parks of Thessaloniki are: maxdTair% ≈ 24%, maxdRh% ≈ 41% and maxdDI% ≈16%.     

几个典型的对流层电波传播附加时延修正模型的数值分析

对几种典型的对流层电波传播附加时延修正模型进行了数值分析 ,为实际工程中选取对流层的附加时延修正模型提供了依据 .