The development of an intervening opportunities model with spatial dominance effects

In this paper an intervening opportunities model with spatial dominance is developed. The usual assumption in spatial theory is that decision makers are influenced not just by the size of a destination or distance but by these two factors in combination, that is, spatial dominance. Decision-makers will have more knowledge about, and clearly perceive destinations that exert the greatest amount of spatial dominance on their origins, just as they would primate cities. Thus destinations are ranked in terms of the spatial dominance calculated for each destination. Empirical verification of the model utilizes state-to-state migration flow data for the US. Calibration results compare favourably with the traditional intervening opportunities model and the production constrained gravity model. Received: 7 October 1999/Accepted: 15 June 2000     

改进Moser法射线追踪

地震波场正演模拟、层析成像、偏移成像经常需要用到射线追踪,本文在基于图形理论的Ｍｏｓｅｒ法基础上,改进其网格节点的划分、追踪时路径的选取,并增加直射线追踪以消除在速度变化不大时射线受节点布置影响出现不合理的折曲现象．     

Fermat's principle for seismic rays in elastic media

We prove that rays in linearly elastic anisotropic nonuniform media obey Fermat's principle of stationary traveltime. First, we formulate the concept of rays, which emerges from the Hamilton equations. Then, we show that these rays are solutions of the variational problem stated by Fermat's principle. This proof is valid for all rays except the ones associated with infection points on the phase-slowness surface.     

The Atacama Cosmology Telescope project: A progress report

The Atacama Cosmology Telescope is a project to map the microwave background radiation at arcminute angular resolution and high sensitivity in three frequency bands over substantial sky areas. Cosmological signals driving such an experiment are reviewed, and current progress in hardware construction is summarized. Complementary astronomical observations in other wavebands are also discussed.     

新疆伽师地区地应力的GPS损伤模拟研究

采用几何损伤理论和方法推导了地壳存在不同方向和大小的断层时的有效应力的公式 ,讨论了利用几何损伤理论来分析和计算地壳中存在不连续断层的理论和方法 ,同时对中国新疆伽师地区的地应力变化用几何损伤理论和方法结合该地区的GPS资料进行了数值计算研究 ,通过比较计算结果与 1 997年 1月至 1 998年 1 2月发生在该地区的MS ≥ 5 .0地震活动可以看出 ,新疆南部的中强地震活动区主要在应力场变化激烈的地区 .     

Profit,reputation and ‘doing the right thing’: Convention theory and the problem of food waste in the UK retail sector

In 2014, Tesco – one of the world’s largest food retailers – revealed that it had generated almost 57,000 tonnes of food waste in its UK operations over the previous twelve-month period. This shocking statistic added to existing evidence of a significant environmental and social problem in the UK and across the world. This paper utilises convention theory to examine the role of major retailers in the context of this global problem and assesses their motivations for acting on food waste. Drawing on interviews with key stakeholders (including major retailers), the analysis investigates their main justifications for action on food waste. It finds that retailers mostly appealed to three conventions or ‘orders of worth’ (civic, market and opinion) and used these as a basis for their commitment to food waste reduction. We argue that the combination of these different justifications is feasible and necessary in the context of the retail sector but that they may also lead to some unintended consequences (in the retail sector and beyond). Crucially, we demonstrate how the dilution of civic justifications (by their financial and reputational counterparts) might produce negative outcomes and inaction as retailers attempt to adhere to the so-called ‘food waste hierarchy’. The paper highlights the continuing significance of convention theory as a framework for analysing possible responses to the social and environmental challenges confronting global agro-food systems.     

超大型铜镍硫化物矿床研究进展

超大型铜镍硫化物矿床不仅赋存有巨大的铂族贵金属资源,而且赋存有非常重要的深源信息,对其成矿理论的多学科综合研究具有重要的理论和实际意义。通过对超大型铜镍硫化物矿床的产出特征、时空分布、构造环境、控矿条件、母岩浆系列、成矿机理等研究现状的总结,认为以下几方面研究具有较大潜力：（１）矿床成因;（２）通过构造—流体—岩浆—成矿动力学综合研究,揭示成矿机制与全球变化的内在关系;（３）元古宙板块构造演化与超大型矿床形成的关系。     

Non-Linear Theory and Power-Law Models for Information Integration and Mineral Resources Quantitative Assessments

Singular physical or chemical processes may result in anomalous amounts of energy release or mass accumulation that, generally, are confined to narrow intervals in space or time. Singularity is a property of different types of non-linear natural processes including cloud formation, rainfall, hurricanes, flooding, landslides, earthquakes, wildfires, and mineralization. The end products of these non-linear processes can be modeled as fractals or multifractals. Hydrothermal processes in the Earth’s crust can result in ore deposits characterized by high concentrations of metals with fractal or multifractal properties. Here we show that the non-linear properties of the end products of singular mineralization processes can be applied for prediction of undiscovered mineral deposits and for quantitative mineral resource assessment, whether for mineral exploration or for regional, national and global planning for mineral resource utilization. In addition to the general theory and framework for the non-linear mineral resources assessment, this paper focuses on several power-law models proposed for characterizing non-linear properties of mineralization and for geoinformation extraction and integration. The theories, methods, and computer system discussed in this paper were validated using a case study dealing with hydrothermal Au mineral potential in southern Nova Scotia, Canada.     

斜底面上的表面波理论

考察了任意倾斜底面上的Kelvin波问题，并用线性化的控制方程分别研究了相应于垂直刚壁的和无限倾斜底面上的表面波频散关系。文中还对任意斜坡上的浅水表面波做了尺度分析，并把决定其频散关系的特征值问题简化为该斜坡上气压扰动的常微分方程，且用数值方法进行了求解。     

基于分数阶时间导数的黏弹性衰减VTI介质中平面波传播

目前在地震勘探频带范围内通常假设品质因子Q与频率无关,且呈衰减各向同性.事实上,相比较速度各向异性,介质的衰减各向异性同样不可忽视.本文将衰减各向异性和速度各向异性二者与常Q模型相结合,建立了黏弹性衰减VTI介质模型,并基于分数阶时间导数理论,给出了对应的本构关系和波动方程.利用均匀平面波分析和Poynting定理,推导出准压缩波qP、准剪切波qSV和纯剪切波SH的复速度、相速度、能量速度以及品质因子的解析表达式.对模型的正确性进行了数值验证,并分析了qP,qSV和SH波在介质中的传播特性.数值试验结果表明：本模型能够实现理想的恒定Q行为,表现了品质因子和速度的各向异性特征,显示出黏弹性增强将导致能量速度和相速度的频散曲线变化剧烈;速度和衰减各向异性参数与传播角度之间的耦合效应对qP,qSV和SH波的速度和能量影响明显;qP,qSV和SH波的频散曲线和波前面随着衰减各向异性强度的改变发生显著变化,其中耦合在一起的qP和qSV波变化趋势相同,而SH波与它们呈现相反的变化规律.本研究为从常Q模型角度分析地震波在衰减各向异性黏弹性介质中的传播特征奠定了理论基础.