1998年1月10日张北-尚义6.2级地震前昌平地震台应变资料的异常变化分析

分析了昌平地震台体应变、线应变及差应变等观测资料在１９９８年１月１０日张北－尚义６．２级地震前的异常变化。结果表明：该次地震前昌平台的应变观测资料出现了明显的趋势异常;体应变的异常时间与震级有较发的相关性;差应变资料显示了短临异常;由线应变资料计算的主应变方向在地震前逐渐向震中偏转;Ｍ２波潮汐因子也出现了明显的异常变化。     

建筑日照测量仪研制

介绍了建筑日照测量仪的研制原理、设计方案及使用方法.仪器通过显示器观察白天太阳周日圈上遮挡物,由编码器测量每个遮挡物所遮挡的日照时间.由于仪器采用机械装置动态模拟了日地方位角变化关系,从而保证了显示器摄像头始终沿太阳周日圈扫描(仪器专利名称;一种建筑日照测量装置,专利号:201120007301.9).对比检验表明,当采用1000脉冲编码器,通过4倍频,其分辩率为21.6s,误差在1.5 min以内.仪器结构紧凑,设计小巧,使用方便,一次常规测量只需几分钟,大大降低了测量成本,达到了现场实测、直观显示的技术要求.该仪器可用于日照纠纷仲裁,建筑日照以及气象、雷达探测环境遮挡角测量.     

海南省三亚市的生态环境建设

三亚市位于海南岛最南部，具有得天独厚的生态环境优势。近20年来，生态环境建设虽取得初步成效，但问题也较突出，如林业尚存隐患，耕地锐减，水域受蚕食和局部环境恶化，城市绿化美化不足等。生态环境建设面临的任务主要是：合理布局城镇，建设具有经济－生态良性循环的城乡体系；完善林业生态体系建设，建成强有力的陆地生态支柱；保护好水体环境，搞好碧水工程建设；保护耕地、保证农业持续发展；整治环境，提高环境质量。为此必须采取相应措施。     

Surface Elevation Distribution of Sea Waves Based on the Maximum Entropy Principle

A probability density function of surface elevation is obtained through improvement of the method introduced by Cieslikiewicz who employed the maximum entropy principle to investigate the surface elevation distribution. The density function can be easily extended to higher order according to demand and is non-negative everywhere, satisfying the basic behavior of the probability. Moreover because the distribution is derived without any assumption about sea waves, it is found from comparison with several accepted distributions that the new form of distribution can be applied in a wider range of wave conditions. In addition, the density function can be used to fit some observed distributions of surface vertical acceleration although something remains unsolved.     

类多变量输出误差系统的耦合多新息辨识方法

辅助模型辨识思想、多新息辨识理论、耦合辨识概念是研究复杂多变量系统辨识的新理念和原理.将它们结合起来研究类多变量输出误差系统的辨识问题,提出了多元辅助模型辨识方法、多元辅助模型多新息辨识方法、变递推间隔多元辅助模型多新息辨识方法.为减小算法的计算量和提高参数估计精度,将系统模型分解为一些子辨识模型,应用辅助模型辨识思想、多新息辨识理论、耦合辨识概念,研究和推导了部分耦合辅助模型辨识方法、部分耦合辅助模型多新息辨识方法.讨论了几个典型辨识算法的计算量,给出了参数估计的计算步骤和计算流程图.     

Ground vibrations from sheetpile driving in urban environment: measurements, analysis and effects on buildings and occupants

Following a comprehensive review of the subject of man-made ground vibrations, measurements of ground vibration caused by vibratory sheetpile driving in recent soil deposits are reported in terms of particle velocities vs. distance from the source of vibration. The measurements were conducted on paved surfaces and sidewalks in the inner urban environment. Reconstructed particle displacement paths indicated, predominantly, vertical vibrations of the Rayleigh type. The attenuation rate of vibrations with distance was compared to published results of other studies and satisfactory agreement was found to exist. Values of particle velocity measured in this study, however, were lower than corresponding values of other studies under comparable values of rated vibratory kinetic energy. This is possibly due to different soil conditions. Average and upper bound linear log–log attenuation relationships are proposed, which fit the results of measurements and are representative of the conditions likely to be encountered in the urban environment. Measurement of vibrations on higher floors of multistory reinforced concrete buildings indicated a significant amplification of vertical vibration and an average curve for amplification magnitude vs. floor level was fitted to the results of measurements. A comparison of measured values of vibration with the observed performance of buildings and with damage threshold values suggested by existing codes and standards indicated that the latter do not provide safety against damage caused by vibratory densification of loose sandy soils. On the other hand, the existing criteria for human exposure to vibrations in buildings, according to the results of this study, seem to adequately define the degrees of human discomfort.     

纹理特征向量与最大化熵法相结合的SAR影像非监督变化检测

合成孔径雷达(SAR)影像具有明显的斑点噪声,在变化检测中,一般需要考虑空间邻域信息。本文结合SAR影像丰富的纹理信息,提出一种考虑空间邻域信息的高分辨率SAR影像非监督变化检测方法,用基于灰度共生矩阵(GLCM)的32维纹理特征向量构造差异影像。通过最大化熵法自动选取阈值,对精度指标随窗口大小的变化进行回归分析,得到适合于变化检测的窗口为11×11。试验表明,本文方法优于马尔科夫随机场法,可以减小斑点噪声的影响,有效提高高分辨率SAR影像变化检测的精度。     

构建新疆兵团水文业务管理体系的思路和建议

本文分析了新疆生产建设兵团管辖区域内水文工作现状、存在的问题,提出构建水文业务管理体系的紧迫性和重要性,提出了依托国家援疆机制、水文重大项目、兵团水利改革发展等机遇逐步建立兵团水文站网监测体系、职工队伍体系、业务管理及服务体系的构想,并就加快推进兵团水文建设以实现全国水文行业统一管理提出思路。     

含水量对高含冰量冻结砂土屈服面的影响

Previous researches on yield properties of frozen soil rarely consider the change of water content. However,water content often changes in practical engineering. So a series of triaxial compressive tests are con⁃ ducted on ice-rich frozen silty sands at -5. 0 ℃ to investigate systemically the effect of water content on yield properties and then to establish a relationship between deviatoric stress and shear strain with change of water con⁃ tent. The experimental results show that with water content changing,there are obvious changes in the stress-strain curves,which show that water content has different influence on hardening law in different ranges of water content. So the concrete form about yield function should be determined according to ranges of plastic shear strain（hardening parameter）and water content to make the yield function simple and accurate. When plastic shear strain is within 1. 00%,deviatoric stress always increases with water content. However,with water con⁃ tent increasing,deviatoric stress firstly decreases and then increases when plastic shear strain is beyond 1. 00%. And water content of 42. 0% can be regard as a turning point. The yield function and the increment type relation between deviatoric stress and shear strain have been established with change of water content by segmented hard⁃ ening principle. The testing results show that experimental values are basically consistent with simulated values. So they can be used to predict yield-surfaces and deviatoric stress-shear strain curves at different water contents. © 2019 Journal of Glaciology and Geocryology. All rights reserved.     

Objective Analysis on Large-scale Circulation Type and Its Links to Precipitation over China

Atmospheric circulation anomaly is a direct cause of weather and climate change. In the past, most researches for the relationship between Weather Type (WT) and precipitation have mainly focused on the subjective classification and diagnosis. Compared to the subjective analysis, objective classification uses more consistent index and standard unification, thus, we can get more WTs, and it has been widely used in many areas. By using daily 12UTC Sea Level Pressure (SLP), Precipitable Water (PW), and 700 hPa wind speed (UV700) data from ECMWF’s Interim Reanalysis, the classification of WTs over China was performed with the method of obliquely rotated T-mode principle component analysis. WT and its link to precipitation over China were further analyzed. The results show that the influence of different WTs on precipitation is not uniform over China, and also show distinctly difference in different seasons. A common feature is that WTs great impact on the regions and months with large precipitation, while less impact on regions and months have with less precipitation. In addition, precipitation trends originating from WT intensity changes are much more deterministic, significant, and predictable than trends from WT frequency changes.