灰色马尔可夫链在混凝土疲劳寿命预测中的应用

本文在灰色预测的基础上，引入马尔可夫链预测，建立起了灰色马尔可夫链预测模型。对混凝土疲劳寿命的实验数据进行预测．得到了精度较高的预测结果。证明了利用灰色马尔可夫链对混凝土疲劳寿命进行预测是一种行之有效的新方法。     

基于加权马尔可夫链的榆林地区年降水状态预测研究

根据榆林地区1951年—2008年的年降水量资料,采用均值—标准差分级法将其分为枯水年、偏枯年、平水年、偏丰年和丰水年五个状态。验证了该序列的马氏性,针对降水量为相依随机变量的特点,采用规范化的各阶自相关系数为权重,建立了加权马尔可夫链模型。对榆林地区2009年,2010年的降水状态进行了预测。结果表明,预测结果与实测情况一致。该马尔可夫链的平稳分布显示,榆林地区年降水量处于平水年的可能性最大、偏丰年的可能性最小。     

基于灰色马尔可夫链的管网漏损率预测

针对城市管网漏损率数据的非线性和随机波动性特点,建立了以马尔可夫链修正灰色GM(1,1)的预测模型,以2005年—2012年全国管网漏损率为研究对象,比较分析了灰色和灰色马可夫链预测结果,指出经马尔可夫链修正后的模型预测精度更高。     

模糊马尔可夫链状模型在矿区降水灾害预测中的应用

基于模糊马尔可夫链状预测的方法和原理 ,以铜绿山矿区北露天旱涝等级的预测作为实例 ,介绍了使用这种模型的方法与步骤 ,提出了具有模糊状态的马尔可夫链的概率计算公式。通过实例预测结果表明 ,利用模糊马尔可夫链模型预测灾变是可行的     

基于灰色-马尔可夫模型的厦门市房价预测

针对房地产营销过程中,价格变化随机性的特点,将灰色GM(1,1)预测与马尔可夫预测有机结合,用马尔可夫模型修正灰色预测的结果,构成灰色-马尔可夫预测模型,并运用该模型预测2011年厦门市商品住宅均价。结果表明,运用灰色-马尔可夫链模型对房价进行预测是可行的。     

沪市建筑业模块走势的随机转移分析

采用上海股市的数据,引入马尔可夫链对上海股市建筑业模块的走势进行了研究,并用马尔可夫链对该模块的运动过程进行了预测.     

基于灰色马尔可夫链的武汉城市建设投资规模预测

为弥补灰色GM（1,1）模型不适合预测随机波动性较大的数据序列等缺点,辅以无后效性的马尔可夫链与之结合,建立灰色马尔可夫链预测模型。针对武汉市城市建设投资规模预测问题,通过建立灰色马尔可夫链模型对其进行分析,得出武汉市城市建设预测投资数据,经过与实际投资数据相比较以及模型精度检验,证实所建立的灰色马尔可夫链模型的预测精度很高。运用本模型来预测武汉市城市建设投资规模是可行的、其预测结果是可信的,也为武汉市城市建设的合理投资提供一定的参考依据     

模糊权马尔可夫模型在桥梁状况预测中的应用

以马尔可夫链方法为基础,针对桥梁技术状况值为相依随机变量的特点,采取以规范化的各阶自相关系数为权重,用加权马尔可夫链来预测未来技术状况,在此基础上,根据模糊集理论中的级别特征值,计算出具体的技术状况值,最后,以一实桥前20年的检测资料为实例,对该方法进行了具体的应用,并与灰色模型及灰色马尔可夫链模型等的计算结果进行对比分析,证实了该模型的预测精度。     

火灾事故的灰色马尔柯夫模型预测

灰色马尔可夫模型是将灰色系统理论和马尔可夫链理论相结合建立的预测模型,它不仅充分发挥了灰色预测模型和马尔可夫预测模型的优点,而且有效地解决了灰色预测模型对于随机波动性较大的数列预测精度低的问题.实例计算证明:火灾事故灰色马尔可夫预测模型预测精度高于GM(1,1)模型预测精度,模型可以用于火灾事故预测.     

灰色马尔可夫模型在火灾事故预测中的应用

在火灾事故灰色预测模型的基础上,引入马尔科夫链预测理论,建立火灾事故灰色马尔可夫模型。该模型解决了灰色预测模型对于随机波动性较大的数列预测精度低的问题。实例计算证明:灰色马尔可夫模型的预测精度高于GM(1,1)模型的预测精度,可以较好地用于火灾事故的预测。     

Estimating the amenity value of rainfall

The amenity value of two measures of rainfall are investigated in this study: long term average annual rainfall and the variation in rainfall within the year. Estimates of the economic value of rainfall and variation in rainfall are found using the hedonic property value technique. The results indicate that rainfall is an attribute for which the distribution as well as the average annual level is important. Home buyers prefer less annual rainfall, but, holding annual rainfall constant, buyers will also pay more for greater seasonal variation in rainfall.The author thanks Gardner Brown, Robert Mendelsohn, and George Parsons for their comments and suggestions with this research. Any errors and omissions remain the author's responsibility. Research supported in part by the Nevada Experiment Station.     

Regression models for estimating storm runoff load and its application to Lake Kasumigaura

Regression models are proposed for accurate estimation of storm runoff load. Regression equations are obtained for the relationship between final cumulative load and flow during direct runoff by each storm event. The models are applied to estimate annual nutrients load by all influent rivers into the Lake Kasumigaura for a model year of average annual rainfall. The load in dry weather is calculated from observed data of all influent rivers. Total annual load for a year is the sum of loads in dry weather days and loads in wet weather days. The ratios of the load in a wet weather day to total annual loads are 29 percent for T‐N, 51 percent for T‐P, 53 percent for T‐COD, 22 percent for D‐N, 22 percent for D‐P and 30 percent for D‐COD.     

雨量变化对珊瑚岛礁淡水透镜体的影响

为探索雨量变化对珊瑚岛礁淡水透镜体的影响，应用质量守恒、Darcy定律和Ghyben-Herzberg比率，推导了珊瑚岛礁淡水透镜体的数学模型。根据西沙地区1989年-1998年10年的月均降雨量及最高、最低年降雨量，用有限差分法计算了永兴岛淡水透镜体的外型和贮水量的变化。结果表明，永兴岛淡水贮量4月最小，10月最大，相差值为4月贮水量的10．5％，而10年间降雨量最大和最小年淡水透镜体贮量与平水年相比，分别多16．8％乖少7．2％，这一结果可用于制定淡水透镜体的开采战略，实现淡水资源的安全、科学、持续开发利用。     

Statistical evaluation on storm sewer design criteria under climate change in Seoul,South Korea

This study conducted statistical analysis under both stationary and non-stationary climate using rainfall data measured in Seoul, South Korea. The 50 year annual maximum rainfall data were analysed with generalised extreme value distribution and Gumbel distribution. Possible rainfall changes were predicted with nonstationary forms of the two distributions, considering time variable location parameters. The current storm sewer design criteria were assessed by reflecting climate change implications and expected lifetime performance. Expected return periods were reduced to 4.67, 8.66, 19.16 and 23.53 years for the current 10 min - 5, 10, 30 and 50 years. The newly suggested design criteria of 5, 10, 30 and 50 yr return period storm events were 5.3, 12, 48 and 107 years for the 10 min duration for a 50 year lifetime expectancy.     

Local climate assessment: a meso-scale analysis of long period rainfall in a rural dry sub-humid district from India

The present study investigates the temporal variability in monthly, seasonal and annual rainfall over a drought prone district in India. Long period rainfall data, from 1950 to 2012, were investigated over the district by analysis of anomalies and application of both parametric and non-parametric statistical tests. Decline in annual rainfall is evident in the study area with highest number of below mean rainfall years observed in the recent decade (2000–2009). Only 25% of the annual rainy days span across pre-monsoon, post-monsoon and winter season, reinforcing the high dependence of local communities on monsoonal rainfall for effective crop growth. Against this, a decreasing trend in monsoonal rainfall is noticed over the years. In conclusion, the present paper argues for district level rainfall studies which will provide local stakeholders with the necessary information for better planning and management of rainfall dependent development sectors, thus resulting in reduced overall socio-economic upheaval of rural communities.     

利用基于气象因素的BP神经网络对污闪进行预测的探索

对绝缘子污闪的预测进行了研究。污闪的发生与当地的气象因素有密切的关系,结合当地的气象条件研究污闪的发生,建立当地的年度降水、积污期气温与污闪的BP神经网络,根据乌鲁木齐的气象特征与当地的污闪状况利用matlab软件进行了仿真,能够较好地预测次年的污闪发生情况,结果与实际情况比较符合。     

Evapotranspiration from subsurface horizontal flow wetlands planted with Phragmites australis in sub-tropical Australia

The balance between evapotranspiration (ET) loss and rainfall ingress in treatment wetlands (TWs) can affect their suitability for certain applications. The aim of this paper was to investigate the water balance and seasonal dynamics in ET of subsurface horizontal flow (HF) TWs in a sub-tropical climate. Monthly water balances were compiled for four pilot-scale HF TWs receiving horticultural runoff over a two year period (Sep. 1999-Aug. 2001) on the sub-tropical east-coast of Australia. The mean annual wetland ET rate increased from 7.0 mm/day in the first year to 10.6 mm/day in the second, in response to the development of the reed (Phragmites australis) population. Consequently, the annual crop coefficients (ratio of wetland ET to pan evaporation) increased from 1.9 in the first year to 2.6 in the second. The mean monthly ET rates were generally greater and more variable than the Class-A pan evaporation rates, indicating that transpiration is an important contributor to ET in HF TWs. Evapotranspiration rates were generally highest in the summer and autumn months, and corresponded with the times of peak standing biomass of P. australis. It is likely that ET from the relatively small 1 m wide by 4 m long HF TWs was enhanced by advection through so-called “clothesline” and “oasis” effects, which contributed to the high crop coefficients. For the second year, when the reed population was well established, the annual net loss to the atmosphere (taking into account rainfall inputs) accounted for 6.1-9.6 % of the influent hydraulic load, which is considered negligible. However, the net loss is likely to be higher in arid regions with lower rainfall. The Water Use Efficiency (WUE) of the wetlands in the second year of operation was 1.3 g of above-ground biomass produced per kilogram of water consumed, which is low compared to agricultural crops. It is proposed that system level WUE provides a useful metric for selecting wetland plant species and TW design alternatives to use in arid regions where excessive water loss from constructed wetlands can be problematic. Further research is needed to accrue long-term HF TW water balance data especially in arid climatic zones.     

城市化效应对上海短历时设计暴雨强度的影响

了解城市化对短历时设计暴雨强度的影响，对改善市政基础设施的设计、管理有重要意义。利用上海徐汇区40年完整的降雨资料和市郊站点25年的短历时降雨年最大值资料，分别推求了上海市中心城区和市郊区县的暴雨强度公式。通过同一时期中心城区和区县设计雨量的对比，结合气候和地理因素的影响分析，揭示了上海中心城区与市郊短历时设计暴雨强度的差异及其与重现期的关系。在国内目前的设计重现期下，城市化效应对上海城区排水系统的设计标准并无实质性影响；重现期〉1a，则中心城区的设计雨量反而小于郊县，其暴雨强度公式应用于多数区县排水系统的设计不甚安全；南汇区的短历时设计暴雨强度明显大于中心城区，其排水系统设计宜考虑采用当地的暴雨强度公式。     

The effect of precipitation and air temperature on land‐cover change in the Sahel

Vegetation changes in the Sahel region are strongly affected by variation in rainfall, but air temperature has been considered a relatively minor climatic factor in previous studies. However, soil moisture, the major water source for vegetation in arid and semiarid regions, is generally dependent on temperature‐controlled evaporation. Therefore, we can hypothesize that air temperature modifies the sensitivity of vegetation greenness to rainfall because water loss in soil is critically vulnerable to temperature, although Sahel plants can tolerate high temperatures. In this study, the annual mean of daily maximum air temperature was used as a constraint in analyzing the relationships between annual changes in the cumulative enhanced vegetation index (EVI) and total rainfall. We found that rainfall increase in hotter years could not well induce land greening, and decreased rainfall in cooler years did not necessarily cause vegetation degradation. This presents the importance of temperature as a climatic component in understanding the mechanism of rainfall‐induced land‐cover changes in the Sahel region.     

城市暴雨强度公式数据采样新方法

随着计算机技术的发展,降雨资料将由原先的自记雨量记录资料转换成统一格式的逐分钟降雨量记录电子数据。针对这种纸质文件资料电子化、图形文件资料数据化的情况,开发出了新的城市暴雨强度公式数据采样方法,该数字化采样方法可以与气象局提供的电子数据进行无缝衔接,采用年多个样法和年最大值法两种方法选取样本。该方法避免了人为取样的主观性,同时大大减轻了样本采集的工作量,提高了统计资料的可靠性与统计方法的合理性以及公式推求的效率和正确性。