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921.
《Marine Policy》2017
Projected growth in the international shipping industry is set to outstrip CO2 reductions arising from incremental improvements to technology and operations currently being planned and implemented. Using original scenarios, this paper demonstrates for the first time that it is possible for a nation's shipping to make a fair contribution to meeting global climate change commitments, but that this requires transformation of the sector. The scale and nature of technology change varies depending on the level of demand and how this is satisfied. The scenarios show that to develop successful marine mitigation policy, it is essential to consider the interdependencies between ship speed, level and pattern of demand for services, and the extent and rate of innovation in propulsion technology. Across the scenarios, it is difficult to foresee how deep decarbonisation can be achieved without an immediate, fleet-wide speed reduction; and a land-based energy-system transition strongly influences shipping demand, which in turn, influences the extent of required low-carbon propulsion technology change. Setting the industry on a 2 °C heading requires multifaceted and near-term changes in the shipping sector, but these are unlikely to materialise without a major shift by stakeholders to realise new and innovative deep decarbonisation policies in the coming decade. 相似文献
922.
923.
近年来,强度折减法在岩土工程静、动力稳定性分析领域快速发展。基于该方法,相关学者研究了边坡和隧道的动力稳定安全系数。隧道洞口段是围岩、边坡和衬砌结构相互作用的三维复杂结构体,当前对其地震稳定性研究多集中于定性描述,尚不能给出量化的指标。依托振动台试验,建立相应的洞口段三维数值模型,采用强度折减法,引入结合突变理论的塑性区应变能和其他判据,获得洞口段的动力稳定安全系数。结果表明:结合突变理论的塑性区应变能和其他判据得到的安全系数的最大相对误差较小,在洞口段的地震稳定性分析中采用该判据具有简便、量化等优势;计算出的洞口段的动力安全系数与动力加载降低结构稳定性的一般规律相一致;安全系数为1.52说明洞口段有较高的地震稳定性,与振动台试验的实验现象符合。 相似文献
924.
The effect of blue mussel (Mytilus edulis) presence in eelgrass (Zostera marina) beds was studied from June 2004 to July 2005 in Flensborg fjord, Denmark. The field experiments were conducted at two stations, one with only Z. marina (Eelgrass station) present and one where M. edulis were present in the Z. marina beds (Mixed station). Zostera marina parameters were measured (growth of leaves, shoot density, leaf length, and nutrient content) in combination with epiphyte cover and sediment parameters (sulphate reduction rates, sediment nutrient fluxes, organic content, C, N and P content) to examine possible positive and negative effects of the mussels on eelgrass performance. The fluxes of ammonium from the sediments were stimulated at all sampling dates at the Mixed station, and possibly stimulated epiphyte growth at this station. Further 15N signals in epiphytes from the Mixed station suggested that excretion products from the mussels were important nitrogen sources at this station. Sulphate reduction rates were enhanced at the Mixed station and also sediment sulphide concentrations increased under mussel influence, which may have resulted in sulphide toxicity and decreased growth of Z. marina at this station. The study indicates that for Z. marina beds in Flensborg Fjord the effects of M. edulis in seagrass beds are primarily negative, and raises the question whether this leads to negative effects on the stability and expansion of Z. marina beds. 相似文献
925.
塔中相当部分原油具有高丰度芳香硫——二苯并噻吩(DBTs)特征,其在原油中的绝对丰度高达26 859μg/g,在芳烃中的相对丰度高达58.2%,主要分布在塔中I号构造带下奥陶统、塔中4(TZ4)和塔中1-6(TZ1-6)井区。采用综合地球化学研究途径,对该区原油的高DBTs特征及其主控因素进行初步探讨。分析表明,研究区母源岩较强地控制DBTs的丰度,纯泥岩、页岩中DBTs丰度不高,灰岩、云岩等烃源岩DBTs丰度偏高或超高;观察到在正常油窗范围内,烃源岩和相关原油随成熟度增加DBTs丰度增加,而塔中型高-过熟原油中DBTs丰度有先增加后减小的趋势,表明热成熟作用对该化合物有较强的控制作用;发现生物降解、水洗可使原油中DBTs丰度降低,但对塔中原油中DBTs影响较小;观测到塔中相当部分原油的DBTs含量与硫酸盐热化学还原作用——TSR的作用产物H2S、硫醇、长链烷基四氢噻烷有一定正相关性。对比研究认为,有多种因素控制塔中原油中DBTs丰度与分布,热成熟作用、TSR是导致塔中下奥陶统部分原油高DBTs特征的重要原因,前者可能是主要因素,特殊母源岩因素相对较少,尽管尚不能排除。TZ4井区等石炭系高DBTs原油主要来自深部地层,与下奥陶统抑或更深层高DBTS原油的混入有关。本研究对于该区深层油气勘探具有重要意义。 相似文献
926.
四川盆地东北部三叠系飞仙关组高含硫气藏H2S成因研究 总被引:81,自引:7,他引:81
四川盆地东北部宣汉-开县地区的下三叠统飞仙关组气藏埋深3000-4500m,地温在100℃左右,天然气中H2S含量为12%-17%。这些H2S为飞仙关组气藏附近的硬石膏经硫酸盐热化学还原作用(TSR)而成。与TSR有关的硬石膏,H2S,S^0和FeS2的δ^24S分别为+30.4‰, 12.9‰, 19.1‰和+19.4‰,交代硬石膏的方解石的δ^13C为-7.26‰,δ^18O为-6.41‰,其内所含两相流体包裹体的均一温度为109-151℃。这些高含硫气藏的天然气和储层沥青的热演化程度比其他地区飞仙关组气藏的更高。该区飞仙关组最大埋藏温度超过180℃,但由于后期构造抬升,大于104℃地温的埋藏时间小于20Ma,故气藏H2S含量低于20%。 相似文献
927.
Cataclasis and processes of particle size reduction 总被引:6,自引:0,他引:6
Tom G. Blenkinsop 《Pure and Applied Geophysics》1991,136(1):59-86
The particle size distribution (P.S.D.) of fragmented geological materials is affected by the fragmentation process, initial size distribution, number of fracturing events, energy input, strain, and confining pressure. A summary of literature shows that the fractal dimension (D) of the P.S.D. is increased by the number of fracturing events, energy input, strain, and confining pressure. Cenozoic cataclasis of granite, granodiorites, gneisses and arkose seen in cores from the Cajon Pass drillhole, southern California, produced P.S.D.s with values ofD that varied from 1.88 to 3.08. Each rock type has a characteristic and more limited range ofD. Areas of dilatant texture and modeI fracture-fillings have low average values (2.32 and 2.37) compared to an average value of 2.67 in shear fracture-fillingsD has a good inverse correlation with average particle size. Data from fault rocks in the San Gabriel fault zone, southern California (Anderson
et al., 1983) have been reanalyzed to show that values ofD are higher (2.10–5.52) and average particle size is lower than the Cajon Pass samples, but the ranges of values overlap, and the inverse correlation betweenD and average particle size is extended. Microstructural observations combined with these results suggest that three processes contributed to particle size reduction during cataclasis. The first process of feldspar alteration, which leads to low values ofD, has not been previously recognized. The second process is probably constrained comminution (Sammis
et al., 1987), since the averageD in shear fracture-fillings is close to the value of 2.58 predicted by this theory. A further stage of particle size reduction is demonstrated by an increase ofD with cataclasis. This third process is selective fracture of larger particles, which may also operate during localization and the cataclastic flow-to-faulting transition as observed in experiments. A transition from constrained comminution to selective fracture of large particles, and increasingD values with cataclastic evolution and grain size reduction, may be general features of experimental and natural cataclasis. 相似文献
928.
929.
通过调用新浪微博官方API的方式,获取了四川九寨沟7.0级地震震后微博信息,对获取到的数据进行了分类统计、微博词频统计与时空特征分析。统计分析结果表明:在分类统计方面,地震发生之后24h内,与地震相关微博中人的反应占比达到73%,救援行动占比达到11%,这时由于微博本身特点以及民众对救援的期望造成的。在词频统计方面,高频名词表明震后24h内微博上的热点事件,而高频动词与形容词表明民众会在震后变得焦虑和不安并通过在网上互相激励来缓解震后的不安和焦虑。时间特征表明震后0~4h内,有大量和地震相关的灾情信息会通过微博博文内容的方式发布,而随着应急救援行动的进行,在震后12h以后,民众的情绪会逐渐平复,社会及民众的关注度也随之降低。空间特征表明,由于震后通信中断与网络堵塞,微博灾情基本成点状分布,随后随着通信与网络的恢复、应急救援的进行微博灾情逐渐变为带状分布并进而趋向于形成一个面。 相似文献
930.
介绍了一套自己的水文气象数据查阅和图像显示软件系统。资料包括华北30个水文站的历年径流数据,全国160个气象站四十余年的雨量和气温数据。本软件可以方便地对上要这资料进行查阅和显示,并提供某些统计数据。 相似文献