港珠澳大桥钢管桩施工定位测量技术应用     

易建华  姬翠翠  黄文学  杨银波 《地理空间信息》2014,(5):134-136

海上钢管桩施工定位及其精度监测是港珠澳大桥埋置式承台足尺模型工艺试验研究关键及施测困难的工序之一。通过自行研制的工具式导向架沉桩系统,对钢管桩振沉过程施以约束来提高钢管桩定位精度,满足钢管桩平面定位±5 cm、垂直度1/400的精度要求。根据工程实践,提出影响定位精度的误差来源并给出减小误差的建议。  相似文献   

Dynamics of phytoplankton communities in the Jiangdong Reservoir of Jiulong River,Fujian, South China   总被引：2，自引：0，他引：2  

田永强  黄邦钦  俞超超  陈能汪  洪华生 《中国海洋湖沼学报》2014,32(2):255-265

Phytoplankton blooms occurring in the Jiangdong Reservoir of Jiulong River, Fujian Province, South China, are a potential source of contamination of the drinking water of Xiamen （Amoy） City. To understand the main factors governing phytoplankton composition and succession, we sampled phytoplankton and measured environmental parameters in the reservoir, weekly or biweekly from Jan. 2010 to Feb. 2012. We identified 123 species of phytoplankton from 7 phyla and 74 genera. The major phyla were Chlorophyta, Bacillariophyta, Cryptophyta, Cyanophyta, and Dinophyta. The main trend in the succession of phytoplankton was from prevalence of Cryptophyta-Bacillariophyta communities to those of Chlorophyta-Cyanophyta. High cell concentrations of Cryptophyta, predominantly Komma caudate, Cryptomonas marssonii, and Cryptomonas erosa, were present in winter, associated with low river discharge and cold water. Bacillariophyta, primarily Cyclotella meneghiniana, Aulacoseira granulata, and Aulacoseira granulata var. angustissima, dominated in early spring, coinciding with high turbulence and low irradiance. During early summer and autumn, Chlorophyta, comprising Scenedesmus quadricauda, Dictyosphaerium ehrenbergianum, and Pandorina sp. were prevalent during conditions of warmer water temperatures and low turbulence. Cyanophyta, with dominance ofPseudanabaena mucicola, Merismopedia tenuissima and Raphidiopsis sp. increased throughout the summer, coinciding with higher water temperatures and lower nutrient concentrations. Dinophyta content was occasionally high during winter and summer. Peridiniopsis penardii （Dinophyta） bloomed during winter 2009, with a persistently high biomass recorded into early spring. Canonical correspondence analysis indicated that phytoplankton communities were influenced by river discharge, irradiance, water temperature, and nutrient concentrations.  相似文献   

港珠澳大桥对粤港澳大湾区区域旅游一体化发展影响的计量研究     

张跃  杜洁莉 《热带地理》2023,(7):1275-1287

立足于旅游供需空间系统视角，运用旅游流引力模型及GIS集成方法分析港珠澳大桥建成前后粤港澳大湾区城市旅游竞争力和居民出游力的格局，探讨粤港澳大湾区的区域旅游一体化趋势。研究表明：1）港珠澳大桥的开通使得珠江口东西两岸的旅游流潜力分布更加均衡，有利于珠江口两岸地区的均衡发展，推动港珠澳大桥绿色政策通道建设，打破行政壁垒以实现旅游要素的自由流通，是推动粤港澳大湾区旅游从均衡发展走向区域协同一体化发展的关键。2）大湾区11个城市旅游竞争力和居民出行力的变化幅度与大桥开通后交通可达性的提升幅度显著相关，并呈现明显的空间距离衰减特征；大桥的开通降低了两岸之间的旅游抗阻力，显著加强了珠江口两岸城市的旅游合作关系，尤其是东西岸城市群（香港、深圳、澳门和珠海）之间的资源优势互补。3）港珠澳大桥影响下，粤港澳大湾区旅游竞争力和居民出游力的变化在空间分布上呈现显著的聚集特征，高值集聚区主要分布在大桥直接连接的香港、澳门和珠海；中山及珠海的部分区域被高值邻居包围，受扩散的机会较大；而广佛和深莞的部分区域为低值聚集区，呈现一定的边缘化趋势。大桥对港澳核心城市群优势的加强作用明显，广州及附近区域的相对地位被削弱...  相似文献