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151.
人口迁移的时空分异与影响机制一直是人口学研究关注的焦点。本文基于社保关系转移视角,从时间和空间两个维度探究黑龙江省城镇工作人口省内的中长期迁移规律与时空分异特征,并且结合人口推拉理论与OD模型,综合考虑经济和就业政策因素,建立了能够反映以社保劳动关系转移为基础的中长期人口迁移动力学模型。研究结果表明:基于社保关系的城镇工作人口迁移符合截断指数幂律分布,呈现列维飞行特点;该省省内人口迁出呈现多层级跨区域分布格局,人口迁入呈现“四核心-环东南”格局,人口迁入与迁出空间格局具有一定程度的类似性;黑龙江省边境城市人口流失情况较为严重;城镇职工迁移行为的无序性不断加大,迁移的频率较高;但是经过通过模拟,该省城镇职工的迁移系统趋向于平衡发展。 相似文献
152.
Letícia Fleck Fadel Miguel Jorge Daniel Riera Ignacio Iturrioz 《国际地质力学数值与分析法杂志》2008,32(15):1857-1881
The numerical fracture analysis of non‐homogeneous rock or concrete dowels subjected to shear and compression is described in detail. The method of analysis allows the consideration of scale and rate effects due to material non‐homogeneity and fracture. The proposed approach is verified by comparing numerical predictions with experimental results reported in the literature for a series of small rock samples, since experimental evidence for large bodies is not yet available (2007). Results generated by Monte Carlo simulation using the so‐called discrete element method to model the dowels suggest that a simple three parameters law can be used to predict the relationship between tangential stress at the base and lateral distortion. It is observed that the larger the size of the cubes, the smaller both the peak tangential stress and the rupture distortion. Size effects are also evaluated in samples with vertical restraint. The influence of loading rate is likewise numerically assessed for two sample sizes. The effect is compatible with experimental evidence available for concrete using small samples. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
153.
S. Chatterjee 《Journal of Astrophysics and Astronomy》1991,12(4):269-280
We present here rigorous analytical solutions for the Boltzmann-Poisson equation concerning the distribution of stars above
the galactic plane. The number density of stars is considered to follow a behaviour n(m,0) ∼H(m - m0)m−x, wherem is the mass of a star andx an arbitrary exponent greater than 2 and also the velocity dispersion of the stars is assumed to behave as < v2(m)> ∼ m−θ the exponent θ being arbitrary and positive. It is shown that an analytic expression can be found for the gravitational field
Kz, in terms of confluent hypergeometric functions, the limiting trends being Kz∼z for z →0, while Kz
→ constant for z → infinity. We also study the behaviour of < |z(m)|2>,i.e. the dispersion of the distance from the galactic disc for the stars of massm. It is seen that the quantity < |z(m)|2>∼ mt-θ, for m→ t, while it departs significantly from this harmonic oscillator behaviour for stars of lighter masses. It is suggested
that observation of < |z(m)|2> can be used as a probe to findx and hence obtain information about the mass spectrum. 相似文献
154.
155.
根据目前国内外预应力抗拔抗浮桩、部分粘结预应力抗拔抗浮桩的优缺点以及使用的局限性——长螺旋钻机对于桩径>800 mm或桩长>30 m的桩力不从心,研究了应力分散型预应力抗拔桩及钢筋钢绞线笼系列技术,用于一个直径1 m、桩长60 m的抗拔桩工程,采用旋挖成孔,可实现在工程桩上进行大吨位试桩,受力合理,节省资金和工期,实践证明该系列技术有很好的应用前景。 相似文献
156.
157.
由于地理国情普查是一个全新的、有别于其他测绘项目的新兴项目,在生产过程中难免会出现各种各样的问题。本文结合生产实际,对于地表覆盖分类数据生产过程中出现的一些特征明显、问题集中的错误进行归类解析。 相似文献
158.
《Geoforum》2015
To-date geographical research on encounters has primarily comprised observation of naturalistic settings (both micro publics and everyday public spaces) or narrative accounts of encounters generated by conventional methods, this paper focuses on a contrived spatial experiment to create meaningful contact across difference. Inspired by, and drawing on insights from, Architecture – a discipline relatively neglected by geographers in recent times – we use a creative form of spatial play to stimulate groups of people to explore their differences and to develop shared understandings. Whereas previous studies have identified the importance of material objects in art projects and home spaces in mediating relations between people, surprisingly little attention has been paid to the physical configuration of space in work on encounters, despite the fact that geography is a spatial discipline. Here, we engage directly with the role of the form and function of space. Our spatial experiments demonstrate how paying attention to the materiality of micro-spaces rather than social relations alone, can provide insights into the generation of positive interactions by contributing to a greater understanding of how meaningful encounters happen, and what can be done to facilitate them. Specifically, by exploring the size and configuration of space, issues of ownership and surveillance, the relationship between primary and secondary space, and aural architecture this research identifies how working together to create a shared private or intimate space – might facilitate a sense of empowerment and the production of social relations characterised by democracy and inclusion. 相似文献
159.
The Warsaw International Mechanism for Loss and Damage (L&D) associated with Climate Change Impacts (WIM) was established in 2013 to advance i) knowledge generation; ii) coordination and iii) support to address losses and damages under the UNFCCC. So far, the work undertaken by the WIM Executive Committee (ExCom) has focused on enhancing understanding and awareness of the issue and promoting collaboration with relevant stakeholders. Delivering on the WIM’s third function on action and support has lagged behind, and ‘the political’ nature of L&D has often been blamed for this. Key terrains of contention among Parties have included the positioning of L&D governance vis-à-vis the adaptation space and struggles around state liability and compensation. As a way to facilitate discussion on implementation options, recent research has suggested de-politicising aspects of the L&D debate; yet we have very little insight into how the politics are understood within the realm of international L&D governance. This paper brings an analysis of ‘the political’ into the picture by identifying the complex and underlying issues that fuel contention within UNFCCC L&D negotiations. It gives centre stage to the way different framings of norms and material interests affect the debate, and challenges the tendency in current L&D literature to overlook the socio-historical and political underpinnings of this area of policy-making. We employ a qualitative multi-methods research design which draws on content analysis of 138 official Parties’ submissions and statements, 14 elite interviews with key current and former L&D negotiators and is built on a foundation of 3 years of participant observation at COPs and WIM meetings. We approach this data with a political ethnographic sensibility that seeks to explore how meanings are constructed within and across different sources of data. Our empirical results show that, rather than being a monolithic dispute, L&D catalyses different yet intertwined unresolved discussions. We identify five areas of contention, including continued disputes around compensation; conflicts on the legitimacy of L&D as a third pillar of climate action; tensions between the technical and political dimension of the debate; debates over accountability for losses and damages incurred; and the connection of L&D with other unresolved issues under the Convention. 相似文献