地-气耦合动力系统的研究

研究了一类地-气耦合系统的非线性模型,目的是创建一个地-气振子模型的非线性方程的渐近求解方法,利用变分迭代方法,构造了对应问题解的近似展开式。即首先引入一组泛函和计算出它们的变分,并算出Lagrange乘子,其次,决定变分迭代,最后得到原地-气振子模型非线性问题解的一致收敛的近似展开式。     

Evaluating Local Non-Stationarity when Considering the Spatial Variation of Large-scale Autocorrelation

Multi‐scale effects of spatial autocorrelation may be present in datasets. Given the importance of detecting local non‐stationarity in many theoretical as well as applied studies, it is necessary to “remove” the impact of large‐scale autocorrelation before common techniques for local pattern analysis are applied. It is proposed in this paper to employ the regionalized range to define spatially varying sub‐regions within which the impact of large‐scale autocorrelation is minimized and the local patterns can be investigated. A case study is conducted on crime data to detect crime hot spots and cold spots in San Antonio, Texas. The results confirm the necessity of treating the non‐stationarity of large‐scale spatial autocorrelation prior to any action aiming at detecting local autocorrelation.     

A Trajectory-Oriented, Carriageway-Based Road Network Data Model, Part 2： Methodology

IntroductionIf let roadway entities be denoted by arcs and in-tersections be denoted by nodes, then a road net-work can be represented with node-arc model. Be-cause the designation of nodes can be determinedby arcs according to the definition of node-arc mod-el, howto designate arcs becomes the key of repre-senting a road network. As described in the firstpaper of the series, all four kinds of roadway enti-ties (i.e., streets, road segments, carriageways,and lanes) can be represented by arcs. …     

舟坝水电站水库蓄水对乐山市地震活动的影响及对策

在对铜街子水电站蓄水后库坝区及附近出现的地震活动特点进行分析的基础上,对另外一个舟坝水电站库坝区的地质结构和历史地震活动情况进行探讨,认为舟坝水电站蓄水产生诱发地震的可能性较大,五渡—利店断裂附近的马边、沐川、沙湾等地的诱发地震可能为5级以上,犍为县城附近可能出现的地震为4级左右。针对这些问题提出了减轻诱发地震造成损失的相应对策。     

主动变刚度阻尼多振型半主动控制研究

探讨了开关型半主动控制算法的研究现状,基于单步状态预测控制律,提出了针对高层建筑多自由度结构体系AVS/D(主动变刚度阻尼)多振型开关控制律。通过算例仿真分析与其它开关控制律作了比较,结果表明这种开关控制律是可行的、有效的。特别是在多自由度结构体系振动过程中有多个振型同时在受控结构的反应中起主要作用时,本文提出的开关控制律比其它振型开关控制律有更好的控制效果。     

高层隔震结构模型双向振动台试验研究

对一缩尺1∶16比例高宽比为5的橡胶垫隔震结构模型进行了双向地震动输入振动台试验研究。通过输入不同大小和类型的地震波,分析隔震上部结构和隔震支座的地震反应。试验结果表明:隔震上部结构减震效果较好;隔震支座在某些工况下,竖向可进入非线性受拉变形状态,此时的结构存在倾覆危险。试验相关数据的分析可为高层隔震结构设计理论和规范的编制提供试验依据。     

Thermal regimes and degradation modes of permafrost along the Qinghai-Tibet Highway

Permafrost on the Qinghai-Tibet Plateau (QTP) is widespread, thin, and thermally unstable. Under a warming climate during the past few decades, it has been degrading extensively with generally rising ground temperatures, the deepening of the maximum summer thaw, and with lessening of the winter frost penetration. The permafrost has degraded downward, upward and laterally. Permafrost has thinned or, in some areas, has totally disappeared. The modes of permafrost degradation have great significance in geocryology, in cold regions engineering and in cold regions environmental management. Permafrost in the interior of the QTP is well represented along the Qing-hai-Tibet Highway (QTH), which crosses the Plateau through north to south and traverses 560 km of permafrost-impacted ground. Horizontally, the degradation of permafrost occurs more visibly in the sporadic permafrost zone in the vicinity of the lower limit of permafrost (LLP), along the margins of taliks, and around permafrost islands. Downward degradation develops when the maximum depth of seasonal thaw exceeds the maximum depth of seasonal frost, and it generally results in the formation of a layered talik disconnecting the permafrost from the seasonal frost layer. The downward degrada- tion is divided into four stages: 1) initial degradation, 2) accelerated degradation, 3) layered talik and 4) finally the conversion of permafrost to seasonally frozen ground (SFG). The upward degradation occurs when the geothermal gradient in permafrost drops to less than the geothermal gradients in the underlying thawed soil layers. Three types of permafrost temperature curves (stable, degrading, and phase-changing transitory permafrost) illustrate these modes. Although strong differentiations in local conditions and permafrost types exist, the various combinations of the three degradation modes will ultimately transform permafrost into SFG. Along the QTH, the downward degradation has been proceeding at annual rates of 6 to 25 cm, upward degradation at 12 to 30 cm, and lateral degradation in the sporadic permafrost zone at 62 to 94 cm during the last quarter century. These rates exceed the 4 cm per year for the past 20 years reported for the discontinuous permafrost zone in subarctic Alaska, the 3 to 7 cm per year reported in Mongolia, and that of the thaw-stable permafrost in subarctic Yakutia and Arctic Alaska.     

闽台地区近震震级ML量规函数研究

作者精心地挑选了发生在台湾地区的ML=4.0~5.0壳内地震215个,用福建台网记录到的这些地震的最大地动位移资料,利用多元回归分析方法,拟合出最大地动位移的衰减特征为logA=2.07 231.1/Δ(150km≤Δ≤650km)与之相应的量规函数的表达式为R(Δ)=3.45-231.1(1/Δ-0.01)(150km≤Δ≤650km)对于1999年9月~2005年8月发生在台湾地区地壳内的790个地震,分别利用相关部门在1997年制定的量规函数和上式所示量规函数,求出福建台网测定的平均震级及均方差。结果表明,据前者所得的平均均方差为0.20,而后者为0.18。如果在测定震级时,考虑到台基修正值,则后者为0.13;把测定的结果与台湾相关部门的测定结果进行比较,前者平均低了0.50左右,而后者高了0.08左右。     

浅谈《防震减灾法》在河北省贯彻执行中的问题及对策

从贯彻实施防震减灾法律法规的实践入手,针对《防震减灾法》在河北省贯彻实施过程中存在的问题,进行分析探讨,提出了解决的对策,目的在于更进一步促进防震减灾工作的深入开展。     

Carbon isotope ratios of C_4 plants in loess areas of North China

Recent stable carbon isotope studies have shown that the occurrence of C4 plants on the Earth was much later than that of C3 plants and there was a global ex-pansion of C4 biomass around 5―8 million years ago[1]. Although far fewer species use the C4 pat…