不完整分组数据下离散概率分布的迭代估计方法

研究了在不完整分组数据下对离散型未知寿命分布进行估计,从分组截断数据中推导期望失效数量,通过迭代数值方法计算离散型寿命概率分布,从而避免求解复杂的非线性似然方程组,试验说明该方法有效．     

高阶概率权重矩在洪水频率分布参数估计中的应用

【目的】研究高阶概率权重矩在洪水频率分布参数估计中的应用,为推求洪水频率分布参数估计提供合理的计算方法。【方法】选取广义极值分布作为洪水频率分布模型,推求其高阶概率权重矩计算公式,利用MATLAB语言编程实现其参数的数值求解,并以陕西省赵石窑、绥德、安塞和鹦鸽4个水文站的年最大洪峰流量序列为例进行洪水频率分析。【结果】高阶概率权重矩可以较好地拟合序列中大洪水段的经验点据,计算得到了基于高阶概率权重矩的陕西省赵石窑、绥德、安塞和鹦鸽4个水文站的广义极值分布参数的估计结果,获得WLS准则下赵石窑、绥德、安塞和鹦鸽4个水文站推荐采用的高阶概率权重矩的阶数r分别为:r=4,5,6;r=4,5,6;r=3,4,5和r=3,4,5。【结论】高阶概率权重矩会给予大洪水值较大的权重,可以用于洪水频率分布参数的估计。     

邵力子的“好政府主义”观

“好政府主义”是20世纪20年代极具影响的政治思潮,在当时引起了人们的热烈讨论。邵力子作为反对派的重要代表人物之一,结合当时中国的政治实际,为革命思想立论,对“好政府主义”的政治目标、实施方案进行评价,深刻揭示了其失败的原因,对革命思想的传播起到了促进作用。     

Birch's Law: Why Is It So Good?

Birch's law arises in the physics of solids as a linear approximation, in a certain range of density, of a power law. For a change of chemical composition within the same crystal structure, the velocity-density relation is constant with a slope of nearly -0.5 in the first-order approximation.     

Navigating complex labyrinths: optimal paths from chemical waves

The properties of excitable media are exploited to find minimum-length paths in complex labyrinths. Optimal pathways are experimentally determined by the collection of time-lapse position information on chemical waves propagating through mazes prepared with the Belousov-Zhabotinsky reaction. The corresponding velocity fields provide maps of optimal paths from every point in an image grid to a particular target point. Collisions of waves that were temporarily separated by obstacles mark boundary lines between Significantly different paths with the same absolute distance. The pathfinding algorithm is tested in very complex mazes with a simple reaction-diffusion model.     

防御和减轻气象灾害: 2006年世界气象日主题

\t\t\t\t\t目的\t\t\t\t\t研究全球气候变化背景条件下佳木斯市旱涝灾害演变规律。\t\t\t\t\t\t\t\t\t\t\t\t\t方法\t\t\t\t\t以1951年以来佳木斯市春季逐日降水资料及国家气候中心74项环流指数实时资料为依据,用降水距平百分率R_i和Z指数法分析佳木斯市春季旱涝类型、出现频率及时空分布特点并建立春季降水预报方程。\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t结果\t\t\t\t\t1961—2015年,佳木斯市所属县(市)出现大涝和大旱的频率在72%~96%,1996年以前出现大旱频率较高,而1996年以后出现大涝的概率更大;佳木斯市在年降水量减少的同时,春季3—5月降水变化呈上升趋势,在55年的线性变化趋势中,每10年增加约9.6%;从地域分布看,佳木斯西部地区比东部更易发生旱涝且转换更加频繁;佳木斯春季旱涝趋势主要受前一年春冬季大气环流的影响,以Minitab 16筛选的环流特征量为因子,建立春季降水量预报方程,其预测春季旱涝类型准确率为63.6%。\t\t\t\t\t\t\t\t\t\t\t\t\t结论\t\t\t\t\t研究结果可为佳木斯市春季旱涝灾害的短期气候预测提供参考依据。\t\t\t\t     

乡村善治:内涵、演进及特征——对乡村善治逻辑的中国特色刍议

走乡村善治之路是乡村振兴的重要内容。乡村善治体现的是以治成善或善之治,是基于人的好生活而对治理秩序的美好愿景及其实践活动,因而它成为乡村社会秩序的目标与价值基础。随着国家意识的确立进而有了国家对乡村的整合,乡村善治实现了乡土善治到国家善政,再到现代社会的善治过渡,并在国家及现代化意义上不断获得新的诠释、演进和发展,逐渐形成了国家及现代化、公共利益及其多主体参与等方面的善治特征。国家现代化由此成为乡村善治的逻辑起点。     

Serotonin storage in platelets: estimation of storage-packet size

Storage-body diameter and volume, and the number of molecules of serotonin contained in a storage body, were estimated for blood platelets. In the human, 5.23 x 10(5) molecules of serotonin are contained in a storage body 198 nanometers in diameter, while in the cat, 31.2 x 10(5) molecules of this amine are contained in a storage body 298 nanometers in diameter.     

Paramagnetic unit in spinach subchloroplast particles: estimation of size

A pulsed ruby laser (wavelength, 694.3 nanometers) was used to measure the dependence on light intensity of light-induced electron paramagnetic resonance (ERR) signal 1 for short flashes of uniform duration (400 microseconds). Approximately 10(18) photons per square centimeter per flash from the unattenuated beam were available to the sample of subchloroplast "system 1" particles from spinach. The experimental dependence of the EPR signal height plotted as a function of the total number of incident photons per flash was exponential. From measurement of the slope at a very low relative photon flux and the saturated EPR signal amplitude, the value for the cross section or "effective size" of the light-induced paramagnetic unit, sigma(EPR), was found to be 300 x 10(-17) square centimeter. This result is compared with a measured optical absorption cross section, sigma(694nm), of 2.5 x 10(-17) square centimeter, for the identical sample at the laser wavelength. The hundredfold difference in size supports the thesis that the paramagnetic state is a property of an aggregate of chlorophyll molecules of the same general size as the photosynthetic unit.