90年代加拿大移民地区结构新特点

90年代是战后以来加拿大移民的高峰时期,本文总结了这一时期加拿大移民来源地和居住分布的新特点。其突出表现是：亚洲已成为加拿大最大的移民来源地,其中来自香港、中国大陆和台湾的华人成为最大的移民群体;移民选择大城市,尤其是多伦多、温哥华和蒙特利尔三大都市区作为定居地的倾向进一步加强。     

高温超高压模拟实验研究--Ⅱ.高温高压下烷烃产物的演化特征

对不成熟泥炭样品进行了高压（0.1～2 GPa) 、高温( 200 ℃～400 ℃）模拟实验,并对实验后样品的烷烃产物进行了分析。结果显示,同一压力条件下,温度升高,烷烃参数表现出更成熟的特征;温度较低时（200 ℃）,压力升高,烷烃参数表现出不成熟,温度较高时（400 ℃）,除个别特殊点之外,压力增大,烷烃参数愈来愈不成熟,说明温压条件都是影响有机质成熟的重要因素,压力的存在会抑制有机质的成熟作用。用模拟实验手段来探讨压力的作用和影响,具有重要的理论及实际意义。     

桐柏“三叠纪早期”放射虫的补充说明——答吴浩若

桐柏“三叠纪早期”放射虫的补充说明--答吴浩若杜远生冯庆来(中国地质大学武汉430074)关键词桐柏三叠纪早期放射虫补充说明桐柏地区三叠纪早期放射虫动物群的发现(冯庆来等,1994)引起了许多学者的关注,一些学者对放射虫存在各种怀疑(包括怀疑为混样或…     

一种利用贝叶斯最小判别准则估计未来地震危险的新方法

提出了一种基于最大似然和贝叶斯最小判别准则的新预测方法,它的长处在于对样本数无特殊要求,所以,对低地震活动地区,此模型也能得到与时间有关的稳定的未来强震危险估计。最后,以华北地区为例,说明了本方法的可行性。     

鲁南地区城市房屋震害预测

在文献调查和现场调查的基础上,对鲁南地震重点监视防御区内城市房屋建筑的抗震能力做了分析,给出了抗震救灾重要房屋的单体预测结果、现有房屋的群体预测结果,并对房屋破坏造成的直接经济损失、人员伤亡进行了预测。文中指出了现有房屋的抗震薄弱环节,为该地区采取防震减灾对策提供了依据。     

豫北地区地震活动性及其与区域地壳运动的关系

本根据地震地质和地震分布条带,把豫北地区从西至东分为弱,中,强三个区段。由于区域地壳深部主断裂和大震活动的牵动作用,是造成本地震活动的重要原因,因而从区域地壳块体活动背景上探讨了本区及邻近地区地震活动趋势,中还指出,豫北西部太行山区的林县－薄壁地震带,虽不具有强震构造背景,但小震年月频率多寡和震群活动,却能反映了大区域地壳应力场强弱,亦可作为判断区域性地震活动的指标。     

山东中部一条明显的北西向中强地震带

长清－临沂地震带是山东中部一条明显的北西向中强地震带,由９次中强地震组成。这些地震沿北西向展布,主要分布在四个震源区,大致呈５０￣５５ｋｍ等间距分布。除１６６８年郯城地震与北北东向的郯庐断裂带有关外,其它地震受北西向蒙山断裂控制,是该断裂各为层段新活动的结果。另外,该地城带内地震的发生还有一定深部构造背景。未来应注意研究该带内再次发生中强地震的可能。     

微波遥感大气温度层结的原理和试验

一、引言 利用5毫米微波段大气辐射的地面遥感,反演大气温度压力层结。本文将讨论它的原理、仪器和试验结果。这项工作最初在北京大学进行原理性的探索。随后分别与上海气象仪器厂和北京768厂合作研制成A型微波辐射计及B型微波辐射计两种试验样机,并对两种试验样机作了野外考察试验。从观测结果上看,可以用它遥感十公里以下大气温度层结,低空逆温能够明显地反应,高空逆温反演误差较大。5公里以下均方根误差在2—3°K以内,5公里以上误差还要大些。     

Detecting Arctic snow and ice cover with FY-1D global data

Chinese meteorological satellite FY-1D can obtain global data from four spectral channels which include visible channel(0.58-0.68 μm) and infrared channels(0.84-0.89 μm,10.3-11.3 μm,11.5-12.5 μm).2366 snow and ice samples,2024 cloud samples,1602 land samples and 1648 water samples were selected randomly from Arctic imageries.Land and water can be detected by spectral features.Snow-ice and cloud can be classified by textural features.The classifier is Bayes classifier.By synthesizing five d ays classifying result of Arctic snow and ice cover area,complete Arctic snow and ice cover area can be obtained.The result agrees with NOAA/NESDIS IMS products up to 70%.     

Estimation of seasonal crop water consumption in a vineyard using Bowen ratio‐energy balance method

Information about seasonal crop water consumption is useful to develop the appropriate irrigation scheme. Measurements of energy balance components using the Bowen ratio method were made for a complete growing season at a vineyard in the arid region of northwest China. Vine in the experiment was furrow‐irrigated using a trellis system. The measured evapotranspiration was compared with estimates using the soil water balance method. It is shown that the Bowen ratio method provided accurate estimates of evapotranspiration from the vineyard and this requires that the Bowen ratio system is appropriately installed. The energy balance components showed typical diurnal pattern with peaks that occurred around the midday, except for the ground heat flux which delayed its peak by 2–3 h. The sensible heat flux was greater than the latent heat flux and followed the net radiation closely. The ratio of the latent heat flux to net radiation was low in the early growing season and increased over time. Under the limited irrigation experienced in the vineyard, the latent heat flux was controlled by available soil moisture and the total evapotranspiration in the growing season was 253 mm. The seasonal progression of the crop coefficient is similar to that reported in the literature, with the maximum occurring during the month of September. The crop coefficient can be estimated as a non‐linear function of day of year (DOY) and used to estimate evapotranspiration from vineyards in the region. Copyright © 2007 John Wiley & Sons, Ltd.