Advanced programming methods and data structures for computational modelling using edge‐based finite volume methods

The generation of a numerical model must consider the separate issues of the governing equations, the numerical representation of those equations, the data structure that describes the model, the choice of programming language and finally the implementation and code management issues. These issues are considered as a whole in this paper and as a consequence, 10 golden rules for numerical modelling are proposed. By way of application, a saturated–unsaturated flow problem is modelled using the Richards equation and an innovative edge‐based finite volume method. The implementation uses a novel data structure. This is shown to have over 91% code re‐use and hence code written in this way is highly flexible and applicable to many different problems. By way of example, a compacted core earth filled dam problem has been solved. Finally, we conclude that this advanced programming method can significantly reduce code development time. Copyright © 2004 John Wiley & Sons, Ltd.     

Hazard analysis of seismic submarine slope instability

To assess the risk associated with a submarine landslide, one must estimate the probability of slope failure and its consequences. This paper proposes a procedure to estimate the probability of earthquake-induced submarine slope failure (hazard) based on probabilistic seismic hazard analyses, ground response analyses and advanced laboratory tests. The outcomes from these analyses are treated in a probabilistic framework, with analytical simulations using mathematical techniques such as the first-order reliability method, Monte Carlo simulation and Bayesian updating. Fragility curves of slope failure during the earthquake (co-seismic) and after the earthquake (post-seismic) were developed in this study, and were shown to provide a clear and well-organized procedure to estimate the annual failure probability of a submarine slope under earthquake loading.     

Skin friction features of drilled CIP piles in sand from pile segment analysis

Numerical pile segment analysis is conducted in this study with an advanced soil model to investigate the skin friction behaviour of a drilled Cast‐In‐Place (CIP) pile installed in sand. Although the interface between the sand and pile is considered rough, thin elements adjacent to the pile are used to include effects of localized shear. Unit weights of fluid concrete and accompanied changes in stress are considered as the effects of pile installation. Changes in effective stresses are the most prominent effect due to pile installation with a change in direction of the major principal stress from the vertical to the radial direction. Shear behaviour of the sand at the interface during the early shear stage is related to the contractive tendency of the sand at small strain levels. Changes in the stress field around the pile with little changes in volumetric strain take place during the early shear stage. Stress redistributions during the early shear stage depend on the direction of the major principal stress before shear. Results of the pile segment analyses for drilled CIP piles show good agreement with design methods. Parametric studies are used to characterize the effects of sand density and pile diameter on the skin friction behaviour of drilled CIP piles. Copyright © 2007 John Wiley & Sons, Ltd.     

采用大管棚超前支护技术处理青—莱高速公路毫山峪隧道塌方

在青—莱高速公路毫山峪隧道塌方段施工中应用大管棚超前支护技术,施工管棚直径大,钻孔难度大。通过优选钻孔工艺、管棚参数和注浆工艺控制施工质量,大管棚支护施工取得了较好的效果。     

基于高端时尚消费品销售空间的中国城市控制力结构研究

自"世界城市"和"全球城市"研究开始,在对城市控制力的相关研究中,除了传统的人口、经济等属性数据外,研究对象高度集中于生产性的工作空间,即制造业企业和高端生产服务业企业。但卡斯特对其流动空间的理论阐述中明确表述了商务人士除工作地点以外的以高端消费者服务业为代表的消费性空间也应纳入流动空间的控制层-商务精英层之中的观点。因此,在对城市控制力结构的研究中,高端消费者服务业可以成为制造业企业和高端生产者服务业的一个有效的补充。从高端消费者服务业视角出发,通过对高端时尚消费品销售网络空间分布的研究,在多个层面对中国城市的高端生活服务控制力中心结构进行解析。通过研究得到以下主要结论:①城市控制力中心在中国国土范围内呈现菱形结构,从东部直接跳跃至西部,中部呈现为低洼地带;②三大城市群内部的城市控制力多中心结构开始显现,其中长三角地区的发育较为明显;③西部和东北仍呈现单中心据点发育格局。     

辽东半岛中生代韧性剪切带特征及其地质意义

辽东半岛韧性剪切带可分为两种类型,一类为低角度逆冲推覆型,多为北东—南西向或北北东—南南西走向,大致分布于辽东半岛东南边缘;另一类为高角度近水平剪切滑动型,多分布于半岛内部的a线理及运动学特征指示这些剪切带的总体应力场这由南东东向北西西推覆、挤压。剪切带的形成时间大多在中生代末期。辽东半岛金矿大多与这次韧性剪切活动有关,由剪切活动产生的一些韧-脆性的变形带很可能即是环太平洋成矿作用的容矿构造。     

Acid-sulphate Type Alteration and Mineralization in the Desmos Caldera, Manus Back-arc Basin, Papua New Guinea

Abstract: The Onsen acid‐sulphate type of mineralization is located in the Desmos caldera, Manus back‐arc basin. Hydrothermal precipitates, fresh and altered basaltic andesite collected from the Desmos caldera were studied to determine mineralization and mobility of elements under seawater dominated condition of hydrothermal alteration. The mineralization is characterized by three stages of advanced argillic alteration. Alteration stage I is characterized by coarse subhedral pyrophyllite with disseminated anhedral pyrite and enargite which were formed in the temperature range of 260–340°C. Alteration stage II which overprinted alteration stage I was formed in the temperature range of 270–310°C and is characterized by euhedral pyrite, quartz, natroalunite, cristobalite and mixed layer minerals of smectite and mica with 14–15 Å XRD peak. Alteration stage III is characterized by amorphous silica, native sulphur, covellite, marcasite and euhedral pyrite, which has overprinted alteration stages I and II. Relative to the fresh basaltic andesite samples, the rims and cores of the partly altered basaltic andesite samples have very low major, minor and rare earth elements content except for SiO₂ which is much higher (58–78 wt%) than SiO₂ content of the fresh basaltic andesite (55 wt%). REE patterns of the partly altered basaltic andesite specimens are variably depleted in LREE and have pronounced negative Eu anomalies. Normalization of major, minor and REE content of the partly altered basaltic andesites to the fresh basaltic andesite indicates that all the elements except for SiO2 in the partly altered basaltic andesite are strongly lost (e.g. Al₂O₃ = ‐8.3 to ‐10.9 g/100cm³, Ba = ‐2.2 to ‐5.6 mg/100cm³, La = ‐130 to ‐200 μg/100cm³) during the alteration process. Abnormal depletion of MgO, total Fe as Fe₂O₃, LREE especially Eu and enrichment of SiO₂ in the altered basaltic andesites from the Desmos caldera seafloor is caused by interaction of hot acidic hydrothermal fluid, which originates from a mixing of magmatic fluid and seawater.     

车载RTK在测带状图中的应用

使用车载RTK施测带状图可大幅度提高工作效率。先把带状图中线按道路中线模式建入电子手簿,用中线导航使测点不偏离测图区域。车按"之"字形路线前进,车速控制在20km/h以。手簿切换到手动测量或定距自动记录状态,按40m一点密度采集地形数据。为使移动站能接收到基准站足够强度信号,距离控制在5km以内,基准站般站距离控制在10km以内。当移动站卫星信号间歇性失锁,或移动站与基准站之间电台讯号不稳时,所测得数据不可信。此方法只有便于载体运行的环境下才能发挥作用。     

The effectiveness of climate clubs under Donald Trump

On 1 June 2017, President Trump announced that the US intends to leave the Paris Agreement if no alternative terms acceptable to his administration can be agreed upon. In this article, an agent-based model of bottom-up climate mitigation clubs is used to derive the impact that lack of US participation may have on the membership of such clubs and their emissions coverage. We systematically analyse the prospects for climate mitigation clubs, depending on which of three conceivable roles the US takes on: as a leader (for benchmarking), as a follower (i.e. willing to join climate mitigation clubs initiated by others if this is in its best interest) or as an outsider (i.e. staying outside of any climate mitigation club no matter what). We investigate these prospects for three types of incentives for becoming a member: club goods, conditional commitments and side-payments. Our results show that lack of US leadership significantly constrains climate clubs’ potential. Lack of US willingness to follow others’ lead is an additional, but smaller constraint. Only in a few cases will US withdrawal entail widespread departures by other countries. We conclude that climate mitigation clubs can function without the participation of an important GHG emitter, given that other major emitters show leadership, although these clubs will rarely cover more than 50% of global emissions.

Key policy insights

• The US switching from being a leader to being a follower substantially reduces the emissions coverage of climate mitigation clubs.

• The US switching from being a follower to being an outsider sometimes reduces coverage further, but has a smaller impact than the switch from leader to follower.

• The switch from follower to outsider only occasionally results in widespread departures by other countries; in a few instances it even entices others to join.

• Climate mitigation clubs can function even without the participation of the US, provided that other major emitters show leadership; however, such clubs will typically be unable to cover more than 50% of global emissions.

• Climate mitigation clubs may complement the Paris Agreement and can also serve as an alternative in case Paris fails.

     

WWLLN与江苏省ADTD闪电定位系统数据的对比分析

利用WWLLN(World-Wide Lightning Location Network,全球闪电定位网)与江苏省ADTD(Active Divectory Topology Diagrammer,活动目录拓扑图)闪电定位系统数据,对2006—2009年江苏省闪电活动年际变化、月际变化、日变化和空间分布、以及探测效率和探测精度等展开研究讨论。结果表明,WWLLN探测的闪电时空分布趋势与ADTD保持较好的一致性:江苏省白天发生的闪电次数略高于晚上;闪电主要集中发生在6—8月,仲夏闪电最为活跃;一天中闪电频次峰值时间段出现在16时(北京时间)左右;江苏省闪电分布呈现明显的地域性,闪电密度高值区位于省内偏西和偏南地区,大致与江苏省经济发达地区的地域分布相吻合。总体上,WWLLN探测到的闪电频次和闪电密度值比ADTD小一个数量级。随着WWLLN全球测站数目的逐年增加以及WWLLN定位技术的升级完善,WWLLN探测效率和探测精度逐步提高。WWLLN探测效率与回击电流极性和强度大小有关联。