浅谈挤密碎石桩的施工方法

挤密碎石桩施工法是一种振动成桩法,即先用桩管振动成孔,然后填入足够数量的碎石,最后振动密实成桩体。通过振动、挤密的成桩过程,将原地基土振动夯实,桩体与桩间土形成复合地基,达到既处理可液化地基又增强地基的效果。介绍了挤密碎石柱的施工方法和质量检测方法。     

都市聚落系统的形成规律——递增报酬与幂次法则的计算机与数理仿真

幂次法则是一个普遍存在于自然科学与社会科学界的现象,在都市体系中亦可观察到此一现象。过去的文献仅仅对于幂次法则现象进行了观察和解释,并未能完整地解释其形成的机制。本研究尝试由复杂理论中“递增报酬”的观念来探讨幂次现象的成因,采用计算机程序来仿真都市聚落体系形成的过程,并观察递增报酬与幂次现象之关系。该仿真包含了3 种不同的区位发展吸引模式,分别为相邻关系、规模吸引以及同时考虑规模与相邻的混合模式。计算机仿真显示：① 规模吸引与混合两种模式比相邻吸引模式能够更好地解释都市聚落的成长;② 依照递增报酬法则而仿真形成的都市聚落,与幂次现象呈高度相关。随后的数理仿真演算显示,幂次法则为一统计上的普遍现象,但在递增报酬等经济因素驱动下的都市聚落体系结构与真实的状况较为吻合。因此我们推测,递增报酬极可能是形成真实世界幂次现象的机制之一。     

Pb and Th in settling particles in the western Northwest Pacific Ocean: Particle flux and scavenging

A mooring of three conical time-series sediment traps was deployed at two sites in the western Northwest Pacific Ocean for 9 months. Total mass fluxes and activities of ²¹⁰Pb and ²³⁰Th were determined for the settling particles to elucidate their scavenging and transport processes. Sediment samples also were analyzed for ²¹⁰Pb activities. Total mass fluxes, ²¹⁰Pb fluxes and ²³⁰Th fluxes showed large seasonal variations and their weighted mean fluxes tended to increase with depth, with an especially large increase near-bottom. The ratios of the observed ²¹⁰Pb fluxes to the ²¹⁰Pb deficiency fluxes in the upper traps at the two sites were only 0.02 and 0.12, and were attributable to advective export of ²¹⁰Pb from the surface waters. Those ratios in the near-bottom traps ranged between 1.22 and 2.63. This suggests that these high ratios are due to effective particle scavenging, large lateral ²¹⁰Pb import and input of resuspended particles that have not become incorporated into the sediments. The mean total ²³⁰Th fluxes at the near-bottom traps were 4.2–6.7 times higher than that expected from production in the overlying water column. The ²¹⁰Pb activities in the surficial sediments were much lower than those in the near-bottom traps. The ²¹⁰Pb accumulation rates estimated from the excess ²¹⁰Pb inventory in the sediment column were 40–70% higher than the mean ²¹⁰Pb fluxes at the near-bottom traps. The ratios of the ²¹⁰Pb accumulation rates to the ²¹⁰Pb deficiency fluxes at the near-bottom traps ranged between 2.0 and 3.7. The high fluxes of particulate ²¹⁰Pb and ²³⁰Th at the near-bottom traps reflected a combination of enhanced scavenging of dissolved nuclides and the lateral redistribution of particulate matter by downslope and alongshore transports. However, it was not possible to discriminate among the various processes contributing to high nuclide fluxes.     

Influence of the surface microlayer on the flux of nonconservative trace gases (CO,H2, CH4, N2O) across the ocean-atmosphere interface

Gas exchange experiments were conducted in the tropical Atlantic Ocean during a ship expedition with FS Meteor using a small rubber raft. The temporal change of the mixing ratios of CO, H₂, CH₄ and N₂O in the headspace of a floating glass box and the concentrations of these gases in the water phase were measured to determine their transfer velocities across the ocean-atmosphere interface. The ocean acted as a sink for these gases when the water was undersaturated with respect to the mixing ratio in the headspace. The transfer velocities were different for the individual gases and showed still large differences even when normalized for diffusivity. Applying the laminar film model, film thicknesses of 20 to 70 m were calculated for the observed flux rates of the different gas species. When the water was supersaturated with respect to atmospheric CO, H₂, CH₄ and N₂O, the transfer velocities of the emission process were smaller than those determined for the deposition process. In case of H₂ and CH₄, emission was even not calculable although, based on the observed gradient, the laminar film model predicted significant fluxes at the air-sea interface. The results are interpreted by destruction processes active within the surface microlayer.     

滇西试验场重力潮汐观测及其地震响应特征的研究

本文使用Ｎａｋａｉ预处理、Ｖｅｎｅｄｉｋｏｖ调和分析和滑动滤波等方法，对滇西地震实验场下关台ＧＳ１５－２２７重力仪１９８７－１９９２年 观测资料进行了系统分析，，确定了该地区最佳重力潮汐参数及潮汐和非潮汐动态变化背景，并对观察期间的６个震例进行清理，分析了重力异常变化与地震的关系，获得了该地区重力潮汐和非潮汐信息的地震响应特征。     

Ambivalent climate of opinions: Tensions and dilemmas in understanding geoengineering experimentation

Due to the fear of the consequences of climate change, many scientists today advocate the research into—but not deployment of—geoengineering, large-scale technological control of the global climate, to reduce the uncertainty around its efficacy and harms. Scientists propose in particular initiating field trials of stratospheric aerosol injection (SAI). This paper examines how the meanings of geoengineering experimentation, specifically SAI field trials, are reconfigured in the deliberation of the lay public. To this end, we conducted focus groups with Japanese citizens in June 2015 on the geoengineering concept and SAI field trials. Our main findings are as follows: the ‘climate emergency’ framing compelled the lay public to accept, either willingly or reluctantly, the need for ‘geoengineering research’; however, public discourse on SAI field trials was ambiguous and ambivalent, involving both tensions and dilemmas in understanding what the SAI field trial is for and about. Our results exhibit how the lay public wrestles with understanding the social, political, and ethical implications of SAI field trials in multiple dimensions, namely, accountability, controllability, predictability, and desirability. The paper argues that more clarity in the term ‘geoengineering research’ is needed to facilitate inclusive and pluralistic debates on geoengineering experimentation and not to preemptively arrive at a consensus that ‘we need more research.’ We conclude that ambivalence about both the pros and cons of geoengineering experimentation seems to be enduring; thus, instead of ignoring or repressing it, embracing ambivalence is required to keep the geoengineering debate democratic and inclusive.     

Non-thermal transient sources from rotating black holes

Rotating black holes can power the most extreme non-thermal transient sources. They have a long-duration viscous time-scale of spin-down, and produce non-thermal emissions along their spin-axis, powered by a relativistic capillary effect. We report on the discovery of exponential decay in Burst and Triensient Source Experiment (BATSE) light curves of long gamma-ray bursts (GRBs) by matched filtering, consistent with a viscous time-scale, and identify ultra-high energy cosmic rays (UHECRs) about the Greisen–Zatsepin–Kuzmin (GZK) threshold with linear acceleration of ion contaminants along the black hole spin-axis, consistent with black hole masses and lifetimes of Fanaroff–Riley type II (FR II) active galactic nuclei (AGN). We explain the absence of UHECRs from BL Lac objects due to UHECR emissions preferably at appreciable angles away from the black hole spin-axis. Black hole spin may be the key to unification of GRBs and their host environments, and to AGN and their host galaxies. Our model points to long-duration bursts in radio from long GRBs without supernovae and gravitational waves from all long GRBs.     

Pressures on an intensive irrigated cash-crop system in coastal Ghana

This paper outlines the results of recent interdisciplinary fieldwork in Anloga on Keta Lagoon, Ghana. Vegetable production has been undertaken at Anloga since the nineteenth century and is now highly intensive and carefully regulated. Farmers produce shallots and other crops utilising irrigation water, mostly from wells which tap a shallow fresh-water perched aquifer. However, farmers have been expanding their cultivation activities from the lagoon-side, encouraged by a World Bank supported programme which provides for well-sinking and some electric pumps. The project has environmental and socio-economic implications which give cause for concern. The research employs field investigation to explore both the physical and political economy context and implications of recent change and considers the opportunities for community-based water and crop regulation.