城市规模分布的经济绩效——基于中国市域数据的实证研究   总被引：10，自引：7，他引：3  

孙斌栋  李琬 《地理科学》2016,36(3):328-334

基于2010年市域数据,定量分析市域范围的城市规模分布对经济绩效的影响,并探索最优城市规模分布的影响因素。结果表明,① 在控制了其它重要的生产要素后,单中心规模分布具有更高的劳动生产率;② 随着规模由小变大,具有最优经济绩效的城市规模分布形式存在单中心-多中心-单中心的转变;③ 没有发现经济发展水平影响最优城市规模分布的明确证据;④ 西部地区城市规模单中心分布更有助于提高经济绩效。  相似文献   

低渗透储层不同流动单元可动流体赋存特征及生产动态分析——以鄂尔多斯盆地姬塬地区长6段储层为例     

任颖 《地质与勘探》2016,52(5):974-984

利用高压压汞、恒速压汞、核磁共振、铸体薄片、物性等分析测试手段及试油资料,对姬塬地区长6段储层进行了流动单元的划分,同时分析不同流动单元微观孔隙结构特征及其对可动流体饱和度的影响,进而研究其生产动态的差异。结果表明:研究区四类流动单元微观孔隙结构差异明显,是造成其可动流体饱和度差异的主要因素。其中,喉道半径分布形态及主流喉道半径大小起了决定性作用。在油气田开发阶段中,应该根据不同流动单元的微观孔隙结构差异性特征,实施合理有效的开发方案。  相似文献   

Synthesis of Mullite from High-alumina Fly Ash: a Case from the Jungar Power Plant in Inner Mongolia, Northern China     

CHEN Jiangfeng  SHAO Longyi  LU Jing 《《地质学报》英文版》2008,82(1):99-104

In this paper, an experimental study was conducted in order to test the feasibility of sintering mullite directly from the high-alumina fly ash, without adding any extra material. The results show that the mullite contents in most sintered samples are over 70%. The samples sintered from the beneficiated fly ash have a higher content of mullite than those from the as-received fly ash under the same synthetic conditions. To obtain an equal amount of mullite, a higher sintering temperature is needed for the beneficiated fly ash than for the as-received fly ash. Considering the physical properties of sintered mullite, the favorable sintering temperature is 1400℃ for the as-received fly ash and 1500℃ for the beneficiated fly ash. A higher sintering temperature and a shorter holding time are profitable to sintering mullite. The orthogonal test confirmed that the dominant factor affecting mullite synthesis is sintering temperature, and that the most profitable matching conditions are 200 MPa-1500℃-3 h for the as-received fly ash and 200 MPa-1500 ℃-4 h for the beneficiated fly ash.  相似文献   

高铝粉煤灰烧结反应热力学分析与实验     

李歌  马鸿文  谭丹君  邹丹  彭辉  苏双青 《现代地质》2008,22(5)

分别以碳酸钙和碳酸钠为助剂,对高铝粉煤灰在烧结过程中可能发生的化学反应进行研究。基于热力学计算结果,对比了两种工艺的能耗、物耗、温室气体排放量等因素,结合粉煤灰-碳酸钠烧结反应实验,证明以碳酸钠为配料,高铝粉煤灰烧结过程具有一次性资源消耗量少,能耗最低,温室气体CO2排放量最小,且可生产高附加值产品,实现完全清洁生产等优点。因此,选择以碳酸钠为配料分解高铝粉煤灰中的莫来石和铝硅酸盐玻璃相技术路线,具有良好的工业化应用前景。  相似文献   

利用高铝粉煤灰合成莫来石的实验研究     

陈江峰  邵龙义  魏思民 《矿物学报》2008,28(2):191-195

利用粉煤灰合成莫来石具有良好的工业发展前景,但由于普通粉煤灰中Al2O3含量较低使得合成莫来石时必须添加大量工业氧化铝,从而增加了合成成本.利用高铝粉煤灰直接制备M50莫来石以及高铝粉煤灰与少量工业氧化铝混合合成M60和M70莫来石,其物理性能可以达到我国<烧结莫来石>标准(YB/T5267-2005),这大大降低了合成成本.研究表明,用未处理过的高铝粉煤灰直接制备低牌号莫来石(M50)适宜的烧结温度为1400 ℃,用处理过的高铝粉煤灰或合成高牌号莫来石(M60、M70)适宜的烧结温度为1500 ℃;恒温时间对合成莫来石的影响远小于烧结温度,高温下缩短恒温时间比低温下延长恒温时间有利于莫来石的生成.  相似文献   

磷矿粉复合保水材料的制备及性能研究   总被引：1，自引：0，他引：1  

尹秋英  范力仁  沈上越  罗文君  李茂松  宋吉青 《矿物岩石》2008,28(4)

研究以过硫酸钾为引发剂,N,N-亚甲基双丙烯酰胺为交联剂,丙烯酸、丙烯酰胺为主要原料,经部分酸化和无机材料改性处理的活化磷矿粉为主要添加原料,采用水溶液聚合法制备活化磷矿粉/PAA-AM复合保水材料。进而探讨活化磷矿粉添加量、中和度、交联剂和引发剂用量对复合保水剂吸液性能的影响。当中和度为70%、活化磷矿粉、交联剂、引发剂添加量分别为单体的45%,0.04%,0.5%时,所得复合保水材料吸蒸馏水、自来水、生理盐水倍率分别为390倍,200倍,62倍。通过释磷性能研究表明该复合材料具有较好的可持续供磷性能、有利于改良土壤、改善土壤的缺磷状况。同时,还通过谱学分析(XRD和F-IR),探讨该复合材料的释磷机理。  相似文献   

Effects of ionospheric disturbances on GPS observation in low latitude area   总被引：6，自引：2，他引：4  

Wu Chen  Shan Gao  Congwei Hu  Yongqi Chen  Xiaoli Ding 《GPS Solutions》2008,12(1):33-41

In this paper, ionospheric disturbance data from a local GPS network in Hong Kong (low latitude region) are studied in the solar maximum period (2001–2003). The spatial and temporal distributions of the disturbances in Hong Kong are investigated. It is found that strong ionospheric disturbances occur frequently during the solar maximum period, particularly around March and September, and concentrate at the region around geographic latitude 22°N (geomagnetic latitude 12°N). The effects of the disturbances on GPS geodetic receivers, such as loss of lock and measurement noise level, are also analyzed for the 3-year period. It shows that the measurement noise level and the number of losses of lock in GPS data increase dramatically during ionospheric disturbance periods. The behaviors of different types of GPS receivers during the disturbances are also compared.  相似文献   

Fast map matching,an algorithm integrating hidden Markov model with precomputation     

Can Yang  Győző Gidófalvi 《International journal of geographical information science》2018,32(3):547-570

Wide deployment of global positioning system (GPS) sensors has generated a large amount of data with numerous applications in transportation research. Due to the observation error, a map matching (MM) process is commonly performed to infer a path on a road network from a noisy GPS trajectory. The increasing data volume calls for the design of efficient and scalable MM algorithms. This article presents fast map matching (FMM), an algorithm integrating hidden Markov model with precomputation, and provides an open-source implementation. An upper bounded origin-destination table is precomputed to store all pairs of shortest paths within a certain length in the road network. As a benefit, repeated routing queries known as the bottleneck of MM are replaced with hash table search. Additionally, several degenerate cases and a problem of reverse movement are identified and addressed in FMM. Experiments on a large collection of real-world taxi trip trajectories demonstrate that FMM has achieved a considerable single-processor MM speed of 25,000–45,000 points/second varying with the output mode. Investigation on the running time of different steps in FMM reveals that after precomputation is employed, the new bottleneck is located in candidate search, and more specifically, the projection of a GPS point to the polyline of a road edge. Reverse movement in the result is also effectively reduced by applying a penalty.  相似文献   

FY-3B/MWHS性能参数在轨实时监测          下载免费PDF全文

何杰颖  张升伟 《应用气象学报》2016,27(6):709-715

2010年11月5日发射的风云三号B星 (FY-3B) 是我国第2代极轨气象卫星的第2颗星。其上装载的微波湿度计 (MWHS) 在183 GHz水汽吸收线设计了3个大气探测通道,在大气窗区150 GHz设置了双极化通道。该文主要对FY-3B微波湿度计系统进行介绍,分析其在轨5年的性能,对仪器在轨关键性能参数进行了长时间序列分析,结果表明:仪器各通道灵敏度均优于0.4 K,其中通道1,2,4,5的灵敏度优于0.3 K,定标精度稳定在0.3~0.55 K,未出现恶化现象, 同类型在轨载荷星下点处匹配数据交叉比对,相关系数优于96%。分析表明,该仪器在轨性能和数据质量均优于FY-3A微波湿度计。同时,利用微波湿度计实测数据,着重分析2015年6—7月若干台风的生成、演化、增强和消亡的整个过程,并对台风区域强降雨监测进行分析。  相似文献   

共水平轴双叶轮海流机水动力学性能的实验研究     

程友良  雷朝  戴峥峥  陈健梅  吴百公 《海洋技术学报》2016,(1):106-112

针对水平轴单叶轮海流机在低流速时启动性能差、获能少的缺点,采用共水平轴同向旋转双叶轮水轮机进行了水动力学性能的水槽试验.由实验结果研究了共水平轴单叶轮和双叶轮水轮机的功率特性和启动特性,分析了不同上、下游叶轮安装角和叶轮轴向间距对叶轮启动水流速度以及发电机获得功率的影响,并对单叶轮和双叶轮水轮机的运行情况进行了比较.结果表明,共水平轴双叶轮水轮机的启动水流速度较单叶轮低很多,而且能从水流中获得更多的能量.因此,共水平轴双叶轮水轮机能改进一般水平轴单叶轮水轮机难以启动和获能少的不足,更适合于我国低海流流速的实际海况.  相似文献