北京2015年大气细颗粒物的空间分布特征及变化规律

近年来,随着雾霾事件的频发,人们逐渐提高了对雾霾的关注度,PM_2.5作为其首要污染物对大气能见度及人体健康造成了严重影响.因此,本文利用2015年北京12个环境监测站点的PM_2.5、PM₁₀、NO₂、SO₂、CO和O₃的浓度数据和气象数据,综合研究了北京2015年大气细颗粒物的空间变化特征及分布规律.同时,利用空间差异率（COD）统计方法评估了不同地区细颗粒物浓度的差异程度,并结合2015年2次特殊事件（春节和阅兵）,对大气污染特征及其与排放源控制的关系进行了深入对比分析.结果发现,重污染天气集中发生在秋冬季,且污染程度高、持续时间长.城区PM_2.5浓度比郊区高约12 μg·m^-3.东城区与对照区差异最大,COD值为0.24;东城区与西城区差异最小,COD值为0.05.春、夏、秋季颗粒物PM_2.5、PM₁₀浓度日变化较为平稳,在中午有所升高,冬季颗粒物质量浓度明显呈现出夜间高于日间的污染模式.近3年PM_2.5与PM₁₀保持显著的相关性,但PM_2.5/PM₁₀比值呈降低趋势.阅兵期间采取的空气质量管控措施和气象要素共同作用导致PM_2.5浓度下降约72%,市中心的首要污染物为NO₂,郊区首要污染物为O₃和PM₁₀.春节期间烟花燃放对PM_2.5的瞬时贡献量很大,对比春节假期和非假期2个阶段的大气污染特征发现,人口和机动车减少及餐馆暂停营业并没有使北京局地空气质量得到明显改善.该研究结果提示在进行PM_2.5控制的同时也要对O₃浓度有所关注,同时也进一步支撑了北京空气质量改善需要京津冀协同控制这一重要结论.     

盾构隧道纵向地震响应简化动力有限元法分析(英文)

本文重点关注对盾构隧道的纵向地震响应分析方法的研究,提出了一种简化的动力有限元分析方法。这种方法采纳了响应位移法的一些基本思想,采用和响应位移法一样的环梁和土弹簧模型,但采用动力有限元法来评估地基地震动,而摒弃了响应位移法中采用的地基振动为谐波形式的假定。与响应位移法相比,简化动力有限元法能够提高地基震动的计算精度,从而提高结构响应的计算精度;而与三维连续模型相比,新方法的计算规模小得多,从而能够大幅提高计算效率。然后,本文分别采用相应位移法和新提出的简化动力有限元法,对武汉长江隧道盾构段隧道进行了纵向地震响应分析,并对这2种方法计算结果的差异进行了分析。     

Spatial Variation and Space Optimization of the Development of China＇s Circular Economy

China＇s circular economy is still at the initial stage, whose development has many difficulties and problems requir- ing immediate resolution theoretically and practically. Due to the differences of re...     

MEASURED AND PREDICTED VELOCITY AND LONGITUDINAL DISPERSION AT STEAI)Y AND UNSTEADY FLOW,COLORADO RIVER,GLEN CANYON DAM TO LAKE MEAD1

ABSTRACT: The effect of unsteadiness of dam releases on velocity and longitudinal dispersion of flow was evaluated by injecting a fluorescent dye into the Colorado River below Glen Canyon Dam and sampling for dye concentration at selected sites downstream. Measurements of a 26-kilometer reach of Glen Canyon, just below Glen Canyon Dam, were made at nearly steady dam releases of 139, 425, and 651 cubic meters per second. Measurements of a 380-kilometer reach of Grand Canyon were made at steady releases of 425 cubic meters per second and at unsteady releases with a daily mean of about 425 cubic meters per second. In Glen Canyon, average flow velocity through the study reach increased directly with discharge, but dispersion was greatest at the lowest of the three flows measured. In Grand Canyon, average flow velocity varied slightly from subreach to subreach at both steady and unsteady flow but was not significantly different at steady and unsteady flow over the entire study reach. Also, longitudinal dispersion was not significantly different during steady and unsteady flow. Long tails on the time-concentration curves at a site, characteristic of most rivers but not predicted by the one-dimensional theory, were not found in this study. Absence of tails on the curves shows that, at the measured flows, the eddies that are characteristic of the Grand Canyon reach do not trap water for a significant length of time. Data from the measurements were used to calibrate a one-dimensional flow model and a solute-transport model. The combined set of calibrated flow and solute-transport models was then used to predict velocity and dispersion at potential dam-release patterns.     

全息理论与灾害周期性

地球系统是宇宙系统的全息缩影，地球上的灾害和天体之间具有全息关系，同样有恒定的周期性。本文根据全息理论对灾害进行分析预测，并建议在灾害研究中应用全息理论．     

THE SOCIAL IMPACT OF RESERVOIR CONSTRUCTION IN THE URBAN FRINGE: A TEN-YEAR COMPARISON1

ABSTRACT This paper examines the social impact of reservoir construction on a rural community group located in the urban fringe of a major metropolitan area in central Ohio. The study data were collected at three intervals over a ten-year period (1970, 1974, 1980). Evaluation of resident opinions in the affected community revealed significant attitude differences over time for four of the five variables measured. The findings revealed that the study group desired more social stability but had accommodated the changes experienced to date. Responses to the attitude scales showed that the people in the study group were well integrated and were closely identified with each other at all three test periods. Attitudes toward the lake project were significantly more positive over time, and in 1980 the collective community group held a basically neutral attitude about the lake. The development agency was also perceived more positively over time.     

厄尔尼诺事件对河南省降水的可能影响

本文采用小波变换方法分析了近50年来赤道东太平洋月海温距平序列和河南省月降水量距平序列的多层次时间尺度结构，对厄尔尼诺事件和河南降水的周期变化规律进行了对比分析，并讨论了厄尔尼诺对河南降水的可能影响。结果表明，厄尔尼诺事件对河南降水有一定程度的影响；表现为厄尔尼诺年大多对应河南雨涝年，而反厄尔诺年大多对应干旱年；NINO海区SST的冷暖结构和河南降水的旱涝变化之间具有较好的对应关系，而且两者都存在准2年和4－8年的周期变化。     

SPATIAL VARIATION OF PRECIPITATION ON THE TEXAS HIGH PLAINS1

ABSTRACT: Space autocorrelation techniques have been used to reveal the nature and spatial distribution of precipitation in the Texas High Plains. Correlation in precipitation amounts varies with both distance and direction, dropping off rapidly with distance, particularly during the warm season. The analyses can be used to estimate storm characteristics in conjunction with a wide variety of problems dealing with irrigation, crop yields, drainage and water supply, and evaluation of artificial weather modification efforts.     

The relationship between diversity profiles,evenness and species richness based on partial ordering

Problems with the notion of evenness, such as ambiguity, proliferation of indices, choice of indices, etc. can be overcome by a more fundamental, mathematical approach. We show that the Lorenz curve is an adequate representation of evenness. The corresponding Lorenz order induces a partial order in the set of equivalent abundance vectors. Also diversity can adequately be studied through a partial order and represented by a curve derived from the classical Lorenz curve. This curve is known as the intrinsic diversity profile (or k-dominance curve) and was introduced by Patil and Taillie (1979) and Lambshead et al. (1981).