青海平安电磁辐射在中强震前短期前兆异常特征及预报效能研究

分析和整理了青海平安电磁辐射台自1993年7月以来的资料，发现震前平安单台电磁辐射在中强地震临震前有最大脉冲信号，并通过对无震异常，地震异常的分析判断，对其预报效能进行了R值评价。     

德令哈6．6级地震前地震活动及地震序列特征

德令哈6．6级地震发生在青海省地震局2003年度会商确定的应注意地区内，震前测震学出现多项中短期异常。该地震序列从其能量释放比、震级差均符合主震一余震型判断指标，为主震-余震型序列。序列跟踪工作总结出该序列早期阶段(20天内)预测强余震的几项指标。     

石泉ML4．7级地震前天水深井水温的短临异常特征

分析了天水台数字深井水温资料在陕西石泉ML4．7级地震前的异常特征，发现在震前5天内深井水温发生大幅度的降升变化，呈负脉冲形态，表现为典型的脉冲型前兆异常形态特征。     

Distribution of L_g coda Q in the Chinese continent and its adjacent regions

In continent Lg is usually one of the predominant phases recorded by short-period or broad-band seismometers. A ray-theoretical approach shows that Lg wave is the superposition of higher-mode surface waves propagating in the continental crust[1—4]. The g…     

The development of Nemurella pictetii Klapálek (Plecoptera: Nemouridae) in two springstreams in central Europe

From April 1997 to June 1998 Nemurella pictetii populations were regularly sampled in two springstreams at 220 and 850 m a.s.l., respectively, in Hesse (Germany), at approximately 51°N. Random samples of larvae were taken at three week intervals during the vegetation period, and once a month during winter. Sex, instar, body length, head capsule width and wing pad length of all larvae were recorded. Temperatures were recorded every hour, temporal patterns of temperature agreed closely between sites. Mean winter lows were 3.9 °C at both sites, the mean summer high was 11.9 °C at the lower site, as opposed to 9.6 °C at the mountain site.At both sites, adult emergence started in May. At the mountain site, recruitment started in late July and continued into autumn. There was cohort splitting in the young generation. Some individuals grew rapidly until October–November, but last instar larvae first appeared in March the next year. 1600 degree-days above 0 °C were accumulated during complete development. At the lower site, recruitment began in early July, and cohort splitting also occurred. Fast growing summer recruits emerged as adults in late August, having accumulated only 700 degree-days (above 0 °C). Their offspring hatched in November-December and emerged the next spring, having accumulated also only 700 degree-days. However, only part of the population was bivoltine. Many of the summer recruits grew more slowly and accumulated close to 1900 degree days until they emerged the next spring, together with the offspring of their own fast-growing siblings. Dependence of growth rate on temperature could not be estimated and appears to vary with daylength. For example, 3–6 °C support growth and development provided daylength exceeds 10 hrs of light, or is rising.At both sites and in all cohorts individuals emerging earliest were larger than later emerging ones. The size decline is significantly correlated with number of days after the winter solstice. For the first time it is shown that the decline does not occur shortly before adult emergence but actually takes place several instars before the last. Size differences are then carried on, and amplified, during subsequent molts, until adulthood. The literature presently relates seasonal size declines of insects to high or rising temperatures experienced by larvae approaching adulthood. Our data show that, at least in Nemurella, this explanation fails. On average, females were distinctly larger than males. Differences in mean last instar size were noticed also between sites and years. They remain presently unexplained. The mean sex ratio in both populations was close to 1:1.     

Optimum multiple tuned mass dampers for structures under the ground acceleration based on the uniform distribution of system parameters

The five MTMD models, with natural frequencies being uniformly distributed around their mean frequency, have been recently presented by the first author. They are shown to have the near‐zero optimum average damping ratio (more precisely, for a given mass ratio there is an upper limit on the total number, beyond which the near‐zero optimum average damping ratio occurs). In this paper, the eight new MTMD models (i.e. the UM‐MTMD1～UM‐MTMD3, US‐MTMD1～US‐MTMD3, UD‐MTMD1 and UD‐MTMD2), with the system parameters (mass, stiffness and damping coefficient) being, respectively, uniformly distributed around their average values, have been, for the first time here, proposed to seek for the MTMD models without the near‐zero optimum average damping ratio. The structure is represented by the mode‐generalized system corresponding to the specific vibration mode that needs to be controlled. Through minimization of the minimum values of the maximum dynamic magnification factors (DMF) of the structure with the eight MTMD models (i.e. through the implementation of Min.Min.Max.DMF), the optimum parameters and values of Min.Min.Max.DMF for these eight MTMD models are investigated to evaluate and compare their control performance. The optimum parameters include the optimum mass spacing, stiffness spacing, damping coefficient spacing, frequency spacing, average damping ratio and tuning frequency ratio. The six MTMD models without the near‐zero optimum average damping ratio (i.e. the UM‐MTMD1～UM‐MTMD3, US‐MTMD1, US‐MTMD2 and UD‐MTMD2) are found through extensive numerical analyses. Likewise, the optimum UM‐MTMD3 offers the higher effectiveness and robustness and requires the smaller damping with respect to the rest of the MTMD models in reducing the responses of structures subjected to earthquakes. Additionally, it is interesting to note, by comparing the optimum UM‐MTMD3 with the optimum MTMD‐1 recently investigated by the first author, that the effectiveness and robustness for the optimum UM‐MTMD3 is almost identical to that for the optimum MTMD‐1 (without inclusion of the optimum MTMD‐1 with the near‐zero optimum average damping ratio). Recognizing these performance benefits, it is preferable to employ the optimum UM‐MTMD3 or the optimum MTMD‐1 without the near‐zero optimum average damping ratio, when installing the MTMD for the suppression of undesirable oscillations of structures under earthquakes. Copyright © 2003 John Wiley & Sons, Ltd.     

利用NOAA AVHRR数据研究北半球雪盖气候学特征

利用NOAA卫星图像,研究了北半球、欧亚、北美和青藏高原雪盖气候学特征及其变化趋势.指出北半球、欧亚和北美雪盖气候变化趋势基本一致,年均雪盖面积在1987年前后明显下降; 而青藏高原雪盖面积在1984年后明显下降,说明青藏高原雪盖的年际变化与北半球及欧亚、北美不完全一致.     

重塑非饱和粘土抗剪强度参数与饱和度的关系研究

土的饱和度是基于水分状态和密度状态的一个衍生变量。存在因应水分状态变化和因应密度状态变化的两类饱和度变化过程。根据23组不同水分状态和密度状态的UU三轴压缩试验结果,讨论了重塑非饱和粘性土抗剪强度参数与饱和度的关系。数据分析表明:粘聚力与水分状态相关的饱和度的关系是强非线性的,与密度状态相关的饱和度的关系是准线性的。内摩擦角与水分状态相关的饱和度的关系是强非线性的,与密度状态相关的饱和度的关系是弱非线性的。     

柴达木盆地沙尘暴气候特征及其预报

利用1961～2000年柴达木盆地11个气象站的沙尘暴观测资料，分析了柴达木盆地沙尘暴天气的时空分布特征。根据1980～2000年3月至5月的40次沙尘暴天气个例，从高空环流形势、地面冷空气路径、影响因子及其预报指标4个方面进行分析，总结出柴达木盆地春季沙尘暴天气的预报方法。     

用非线性映象法作钦州市月降水量预报的研究

选取反映大气环流作用的500hPa的三个因子场:1956～2001年环流特征量、振幅和位相资料作为预报因子与钦州市1957～2002年5月降水量求相关比,将求得的高相关比因子用非线性映象法制作钦州市1995～2002年5月的降水量预报,试报效果明显。