B-ZCNN的混沌边缘和局部活性域

将由Zhabotinski反应扩散方程对应的非线性细胞网络方程称为B ZCNN ,应用局部活性理论中关于两个状态变量的反应扩散CNNs的结果 ,讨论计算了B ZCNN的局部活性域和混沌边缘域 ,因此确定了该系统可能出现的复杂性动力学行为的系统参数的范围。取处在混沌边缘域内系统参数点进行模拟 ,得到了嵌套式目标斑图等时空有序结构。最后指出局部活性是成矿发生的必要条件 ,研究成矿发生应该从成矿系统参数域的局部活性研究入手。     

随机溶洞介质模型及其波场模拟

提出了一种模拟构造随机溶洞介质模型的新方法.从现有的随机介质模型理论出发,以混合型连续随机介质的每一个局部最大值点作为一个溶洞分布区的中心点,本文引入了溶洞分布区的局部半径d和溶洞面积p这两个模型特征量,采用阀值截取方法模拟构造各种不同形式的随机溶洞介质模型.用局部半径d描述溶洞介质在大尺度上的离散程度,用溶洞面积p描述在各个溶洞分布区中溶洞介质的面积.通过选择从不同的混合型连续随机介质模型出发,选择不同的局部半径d和溶洞面积p,使用阀值截取法,我们可以最终得到能灵活、准确地描述实际复杂溶洞介质的各种随机溶洞介质模型.本文最后在各种不同形式的随机溶洞介质模型中,作了平面弹性波自激自收记录的数值模拟,并得出了一些结论.     

Spatial and temporal variability of annual and seasonal precipitation over the desert region of China during 1951–2005

The spatial and temporal variations of precipitation in the desert region of China (DRC) from 1951 to 2005 were investigated using a rotated empirical orthogonal function (REOF), the precipitation concentration index (PCI) and the Mann–Kendall trend test method (M‐K method). In addition, the association between variation patterns of precipitation and large‐scale circulation were also explored using the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. The results indicated that the spatial pattern of precipitation was primarily the local climate effect significant type, with the first three EOFs explaining a total of 55·3% of the variance, and the large‐scale climate system effect type, which explained 9·8% of the variance. Prior to the 1970s, the East Asian summer monsoon was stronger, which resulted in abundant precipitation in the Inner Mongolia region. Conversely, the climate of the Xinjiang region was controlled by westerly circulation and had lower precipitation. However, this situation has been reversed since the 1980s. It is predicted that precipitation will decrease by 15–40 and 0–10 mm/year in the Inner Mongolia plateau and southern Xinjiang, respectively, whereas it will likely increase by 10–40 mm/year in northern Xinjiang. Additionally, 58–62% of the annual rainfall occurred during summer in the DRC, with precipitation increasing during spring and summer and decreasing in winter. The intra‐annual precipitation is becoming uniform, but the inter‐annual variability in precipitation has been increasing in the western portions of the DRC. The probability of precipitation during the study period increased by 30% and 22·2% in the extreme‐arid zones and arid zones, respectively. Conversely, the probability of precipitation during the study period decreased by 18·5% and 37·5% in the semi‐arid zones and semi‐wet zones, respectively. It is predicted that the northwest portion of the DRC will become warmer and wetter, while the central portion will become warmer and drier and the northeast portion will be subjected to drought. Copyright © 2010 John Wiley & Sons, Ltd.     

防屈曲支撑的工作机理及稳定性设计方法

防屈曲支撑(BRBs)是一种兼具普通支撑和金属耗能阻尼器双重功能的新型支撑形式。虽然其概念简单明确,但是工作机理却较为复杂,而目前人们对此类支撑的本质工作机理还没有得到充分的认识,因此很难提出较为全面合理的构件稳定性设计方法。本文对防屈曲支撑的工作机理进行了剖析,比较了目前已有的构件整体稳定性设计方法并指出了其中存在的问题,进一步提出应重点考虑间隙、边界条件以及摩擦力等因素的"强度-刚度"整体稳定设计方法的观点;从理论上推导了支撑内芯屈服段与约束构件之间的局部挤压力计算公式,揭示了支撑构件局部失稳破坏的机理,并进一步提出应重点考虑内芯板件宽厚比、间隙以及局部约束条件三者相关关系的支撑构件局部稳定设计方法的观点。     

Local fracture‐induced phenomena in steel moment frames

Brittle fractures were observed at the welded beam‐to‐column connections of a number of steel moment frame buildings following the M6.7 1994 Northridge earthquake. Such fractures cause a rapid loss of connection strength and stiffness, as well as a sudden release of the strain energy stored by the connection at the time of fracture. Immediately following the fracture, a number of highly transient phenomena occur locally in the members adjacent to the connection, as well as globally in the structure as a whole. Four significant local phenomena were observed locally during shaking table tests of a one‐third scale, two‐story, one‐bay steel moment frame in which quasi‐brittle beam‐to‐column fractures occurred: (a) change in beam deflected shape; (b) change in moment distribution in adjacent members; (c) generation and propagation of elastic waves; and (d) initiation of dynamic modal response at the member level. Owing to the highly transient nature of these phenomena, they were observed to have second‐order effects on overall behavior of the system. In comparison, the reductions in local strength and stiffness caused by the fractures had much more significant effects on system behavior. Copyright © 2008 John Wiley & Sons, Ltd.     

局限性胸腔积液的X线与CT分析研究

笔者总结了３２例局限性胸腔积液的Ｘ线与ＣＴ影像学表现,发现其影像学有特异性表现,对于鉴别胸腔积液与良、恶性肿瘤亦起到重要作用。     

Adjustment of wind-drift effect for real-time systematic error correction in radar rainfall data

An effective bias correction procedure using gauge measurement is a significant step for radar data processing to reduce the systematic error in hydrological applications. In these bias correction methods, the spatial matching of precipitation patterns between radar and gauge networks is an important premise. However, the wind-drift effect on radar measurement induces an inconsistent spatial relationship between radar and gauge measurements as the raindrops observed by radar do not fall vertically to the ground. Consequently, a rain gauge does not correspond to the radar pixel based on the projected location of the radar beam. In this study, we introduce an adjustment method to incorporate the wind-drift effect into a bias correlation scheme. We first simulate the trajectory of raindrops in the air using downscaled three-dimensional wind data from the weather research and forecasting model (WRF) and calculate the final location of raindrops on the ground. The displacement of rainfall is then estimated and a radar–gauge spatial relationship is reconstructed. Based on this, the local real-time biases of the bin-average radar data were estimated for 12 selected events. Then, the reference mean local gauge rainfall, mean local bias, and adjusted radar rainfall calculated with and without consideration of the wind-drift effect are compared for different events and locations. There are considerable differences for three estimators, indicating that wind drift has a considerable impact on the real-time radar bias correction. Based on these facts, we suggest bias correction schemes based on the spatial correlation between radar and gauge measurements should consider the adjustment of the wind-drift effect and the proposed adjustment method is a promising solution to achieve this.     

Moment magnitude determination of local seismic events recorded at selected Polish seismic stations

The paper presents the method of local magnitude determination used at Polish seismic stations to report events originating in one of the four regions of induced seismicity in Poland or its immediate vicinity. The method is based on recalculation of the seismic moment into magnitude, whereas the seismic moment is obtained from spectral analysis. The method has been introduced at Polish seismic stations in the late 1990s but as of yet had not been described in full because magnitude discrepancies have been found between the results of the individual stations. The authors have performed statistics of these differences, provide their explanation and calculate station corrections for each station and each event source region. The limitations of the method are also discussed. The method is found to be a good and reliable method of local magnitude determination provided the limitations are observed and station correction applied.