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41.
中国居民工作日与节假日的城际出行网络异同性研究   总被引:4,自引:1,他引:3  
李涛  王姣娥  高兴川 《地理学报》2020,75(4):833-848
居民出行目的、出行时间与地域属性的差异都会导致出行行为的异质性,工作日与节假日具有完全不同的时间属性,且出行目的差异较大,对两时段城际出行网络进行比较有助于全面认识城际出行规律及其网络特征。以4月份工作日(2016年4月11日—4月15日)和国庆黄金周(2016年10月1日—10月7日)为代表,利用“腾讯迁徙”提供的居民城际出行数据,从城市节点、城际关联及网络集聚角度对工作日与节假日的居民城际出行网络结构特征进行对比研究。结果发现:① 黄金周的日均城际居民出行规模显著高于工作日,但出行距离和网络集聚程度明显低于后者;② 两种网络均形成了跨区域组团、邻近组团和省域组团3种类型。黄金周跨区域组团数量明显低于工作日,区域和地方枢纽城市数量多于工作日,邻近组团和省域组团数量则明显高于工作日;③ 工作日,北上广三大城市核心地位突出,旅游功能、交通枢纽功能城市的地位在黄金周更得以凸显;④ 工作日城际出行网络以跨区域联系为主,而黄金周则呈现出明显的空间邻近效应,并形成了以省会为中心、省内出行为主的核心—外围模式。  相似文献   
42.
This paper provides an analytical review of the development of distant water fisheries and the implementation of vessel monitoring systems (VMS) in Taiwan. Taiwanese distant water fisheries have gone through several stages in development: rebirth from the damage of World War II up until the early 1970s, stagnation during the mid-1970s to early 1980s, unbridled growth in the late 1980s to a peak in the 1990s–early 2000s, and a stage of disruption and transformation since the mid-2000s. There were two major fisheries in this stage: tuna and squid, both of which rank between the world's first and third largest. Development was mainly driven by national promotion programs and vessel-building restricting policies; and international influences such as oil crises, declaration of exclusive economic zones, and legal arrangements that stimulated strengthening of international management measures. Growth in Taiwan's over-developed fisheries has outpaced the incommensurately scaled Taiwanese fisheries management sector that has not expanded in parallel with the fisheries. Monitoring of vessel activities remains a major management issue. VMS, which can provide both national and international bodies with an essential monitoring capability for ensuring resource management, was found to be one of the important solutions to this issue. The system, however, was initially unacceptable to the fishers, and the government has transformed external pressures arising from international arrangements and management measures into a force for promoting installation of VMS on Taiwanese fishing vessels. This has occurred in stages: a trial period during 1989–1992; initial development during 1994–1996; expansion during 1996–2004; and a more mature stage of enhanced implementation from 2005 to the present.  相似文献   
43.
对工程场区溶洞、溶隙的埋深、充填物及其性能、顶板厚度与洞跨、荷载作用形式及大小等因素进行综合分析,判断溶洞、溶隙的稳定性及其对工程建设运营的影响,提出相应的处治方案。  相似文献   
44.
集群技术越来越多地应用在提高系统的稳定性和对数据中心的保护等关键应用领域。本文简述了高可用集群技术的有关概念、Veritas Cluster Server工作原理以及湖北省国土资源电子政务系统如何利用高可用性集群搭建数据库和GIS应用服务的相关案例。  相似文献   
45.
The annual loads of nutrients (TOxN equal to nitrate+nitrite; ammonium, phosphate, silicate) to all the estuaries on the mainland of the United Kingdom were estimated from data on water flow through gauging stations at the tidal limits of estuaries, and from concentration measurements under the Harmonised Monitoring Scheme of nutrient concentrations in water samples from these stations. The annual loads of nutrients showed distinct regional variations, with estuaries along the west coast of Wales and northern Scotland having much smaller loads than those along the east coast of England. The largest nitrogen loads were of TOxN, and ammonium loads were usually small in comparison. The Severn, Mersey, Humber and Thames had the highest loads, although these were small in relation to the larger continental European estuaries. Loads of TOxN per unit of catchment area were surprisingly constant (about 105 moles N km−2 y−1). The nutrient loads showed that most U.K. catchments were influenced by human activity, the majority being in the ‘ moderately influenced ’ category. Nutrient loads were also normalized for the area of each estuary, as a measure of the relative influence of nutrients on the receiving estuaries. The ratios of N:P, N:Si and P:Si in the annual loads suggested that most estuaries were likely to be, if anything, P limited rather than N or Si limited. However, crude annual loads may conceal significant seasonal variations.The spring maximum chlorophylla concentrations in coastal waters adjacent to each estuary were significantly correlated with the log total annual loads of TOxN, ammonium and phosphate (but not silicate) for each estuary, providing a direct link between a measure of the degree of biological response in coastal waters and the nutrient load through the estuaries. There were no significant correlations between spring maximum chlorophyll a concentrations and either catchment-normalized or estuary-normalized nutrient loads. There was significant correlation between catchment area-normalized loads of phosphate and an urbanization index for the catchments, but not with the catchment area-normalized loads of the other nutrients.  相似文献   
46.
汤绪 《气象》2014,40(3):261-268
本文以综合分析世界气象组织(World Meteorological Organization,WMO)气象服务发展战略的实施、相关计划活动的组织以及有关国家气象部门的成功示范为基础,结合近一段时间参与未来气象服务战略的制定与推动工作的实践,从五个方面阐述了其发展方向、主要内涵与重点。其中包括:(1)关于WMO气象服务战略及实施的思路;(2)强化与促进在政府应急管理(ERA)和防灾减灾(DRR),构建社会抗灾能力(Resilience)中作用的发挥;(3)鼓励与推动建设气候服务用户交互平台(UIP)与综合天气、气候、水和环境相关服务系统的实践;(4)鼓励与指导以无缝隙业务技术[各种专业领域如海洋气象、各类预报预测技术(次季节-季节预测技术)等]为支撑的新型服务业务的发展;(5)鼓励与推动构建智慧(Smart)型公共服务体系的建设。重点论述如何充分应用现代信息网络与通信技术,建立智能化信息平台,通过气象信息提供方式的变化,增强信息提供的技术含量及提供的个性化与互动能力;发挥社会资源及媒体在气象服务中的重要作用与积极作用;体现"以人为本",关注健康、关注环境、关注出行、关注安全等的理念,实现气象服务社会价值,体现气象服务群体的社会责任等内容。与此同时,本文还从青年人的担当与责任的角度,阐述了(1)青年人的社会责任,勇当服务先进文化的践行者;(2)努力学习,积极创新,做好应用气象的技术准备与技能储备,发挥好新型服务的主力军作用;(3)勇于创业,在未来政府气象管理、社会化、市场化气象服务中建功立业;阐明了对如何发挥青年人在新型气象服务社会架构中的作用的意见。  相似文献   
47.
48.
It is proposed that the Straightforward Inversion Scheme (SIS) developed by the authors for 1D inversion of resistivity sounding and magneto-telluric sounding data can also be used in similar fashion for time-domain induced polarization sounding data. The necessary formulations based on dynamic dipole theory are presented. It is shown that by using induced polarization potential, measured at the instant when steady state current is switched off, an equation can be developed for apparent ‘chargeability–resistivity’ which is similar to the one for apparent resistivity. The two data sets of apparent resistivity and apparent chargeability–resistivity can be inverted in a combined manner, using SIS for a common uniform thickness layer earth model to estimate the respective subsurface distributions of resistivity and chargeability–resistivity. The quotient of the two profiles will give the sought after chargeability profile. A brief outline of SIS is provided for completeness. Three theoretical models are included to confirm the efficacy of SIS software by inverting only the synthetic resistivity sounding data. Then one synthetic data set based on a geological model and three field data sets (combination of resistivity and IP soundings) from diverse geological and geographical regions are included as validation of the proposal. It is hoped that the proposed scheme would complement the resistivity interpretation with special reference to shaly sand formations.  相似文献   
49.
While much work has been done in investigating determinants of oil spillage attributed to vessel accidents, little research has been conducted on the effectiveness of ship hull design in reducing marine pollution. This paper addresses whether the double-hull requirement reduces vessel-accident oil spillage. The volume of oil spillage due to oil-cargo vessel accidents was investigated using tobit regressions and an empirical data set of individual vessel accident pollution incidents investigated by the US Coast Guard from 2001 to 2008. The results indicate that the double hull design on average reduces the size of oil spills by 20% and 62% in tank barge and tanker ship accidents, respectively.  相似文献   
50.
煤矿掘进过程中揭露了小断裂,断裂活化后,煤层下覆岩溶水涌入;矿井突水导致了龙洞坝泉暂时性断流.介绍了突水治理方案:采用物探方法寻找突水井巷,用“地表钻孔注砼法”封堵突水段井巷.该方案能彻底封堵本次突水的导水断裂和龙洞坝泉的水力联系,使龙洞坝泉涌水不会再受本次突水影响,同时,也能解除煤矿受本次突水的危害,为煤矿下一步的恢复工作奠定基础.  相似文献   
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