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171.
Crystallisation of sodium sulfate solutions by evaporation under controlled climatic conditions has revealed the existence
of crystalline hydrated sodium sulfate salts not previously reported. The sodium sulfate phase crystallising and the concentration
of the solution at the point of crystallisation depends on the climatic conditions (temperature and evaporation rate). During
the rehydration of the anhydrous sodium sulfate phase, thenardite, another previously unreported phase was formed prior to
the nucleation of the stable phase, mirabilite Na2SO4 · 10H2O. The addition of organic inhibitors changes both the crystallisation and the rehydration behavior in this system. 相似文献
172.
Structural evidence for large-scale top-to-the-north normal displacement along the Median Tectonic Line in southwest Japan 总被引:1,自引:1,他引:1
Abstract The Median Tectonic Line (MTL) is a first-order tectonic boundary that separates the Sanbagawa and Ryoke Metamorphic Belts. Strike-slip movements on the MTL have been well documented by many workers. New field based structural studies in the Sanbagawa Belt close to the MTL reveal a large number of secondary faults and semibrittle shear bands indicating a top-to-the-north normal sense of displacement. The strikes of these shear zones and their spatial distributions suggest that development of these structures is related to movements on the MTL. These results imply that the MTL has a large-scale normal shear component on a regional scale that can help account for the exhumation of the Sanbagawa Belt. Our proposed history of the MTL can also account for changes in the geometry of folds in the Sanbagawa Belt. 相似文献
173.
S. E. Ahn C. S. Park H. M. Kim 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(6):711-716
This paper is intended to compare the hazard rate from the Bayesian approach with the hazard rate from the maximum likelihood
estimate (MLE) method. The MLE of a parameter is appropriate as long as there are sufficient data. For various reasons, however,
sufficient data may not be available, which may make the result of the MLE method unreliable. In order to resolve the problem,
it is necessary to rely on judgment about unknown parameters. This is done by adopting the Bayesian approach. The hazard rate
of a mixture model can be inferred from a method called Bayesian estimation. For eliciting a prior distribution which can
be used in deriving a Bayesian estimate, a computerized-simulation method is introduced. Finally, a numerical example is given
to illustrate the potential benefits of the Bayesian approach. 相似文献
174.
175.
176.
GIS环境中砂土液化评价方法 总被引:5,自引:0,他引:5
本文介绍了一种适用于GIS环境下分析液化可能性指标的砂土液化分析方法,详细阐述了分析过程和它与GIS的接口情况。 相似文献
177.
本文以政府间气候变化专业委员会(IPCC)于2001年专门报告中关于21世纪内全球气候变化的温度和海平面变化的预估为前提。简要介绍了中国珊瑚礁的定位、类型和分布,对其进行了成熟度分类,评估了全球海平面变化对中国珊瑚礁的影响。据预测,21世纪我国各海域海平面上升以南海最大,为32 ~ 98cm,其平均上升速率为0.32 ~ 0.98cm/a。从海平面上升速率与珊瑚礁生长速率的理论对比分析,中国珊瑚礁基本上能与前者同步生长,即使海平面以预估高值上升,也不会威胁其生存。从中国珊瑚礁成熟度较高、其生长趋势以侧向生长为主的现实状况出发,未来全球海平面上升能为其创造向上生长的有利条件。从古地理学“将古论今”观点出发,自全新世6000aBP以来曾存在过的高海平面和较高表层海水温度的历史,也可以佐证,21世纪的全球海平面上升不会对中国珊瑚礁的存在和发育造成威胁。现存的珊瑚礁岛应对于全球海平面上升,可以做到“水涨岛高”,它们能够屹立于上升了的未来海平面之上;但对于岛上的人工建筑物则会被浸、被淹,或被淘蚀和破坏,因此必须根据海平面上升的幅度和速率,采取相应的防御措施。 相似文献
178.
179.
A neighbor decay cellular automata approach for simulating urban expansion based on particle swarm intelligence 总被引:1,自引:0,他引:1
Jiangfu Liao Guofan Shao Quanyi Qiu Cuiping Wang Shuanning Zheng 《International journal of geographical information science》2014,28(4):720-738
Simulation and quantitative analysis of urban land use change are effective ways to investigate urban form evolution. Cellular Automata (CA) has been used as a convenient and useful tool for simulating urban land use change. However, the key issue for CA models is the definition of the transition rules, and a number of statistical or artificial intelligence methods may be used to obtain the optimal rules. Neighborhood configuration is a basic component of transition rules, and is characterized by a distance decay effect. However, many CA models do not consider the neighbor decay effect in cellular space. This paper presents a neighbor decay cellular automata model based on particle swarm optimization (PSO-NDCA). We used particle swarm optimization (PSO) to find transition rules and considered the decay effect of the cellular neighborhood. A negative power exponential function was used to compute the decay coefficient of the cellular neighborhood in the model. By calculating the cumulative differences between simulation results and the sample data, the PSO automatically searched for the optimal combination of parameters of the transition rules. Using Xiamen City as a case study, we simulated urban land use changes for the periods 1992–1997 and 2002–2007. Results showed that the PSO-NDCA model had a higher prediction accuracy for built-up land, and a higher overall accuracy and Kappa coefficient than the urban CA model based on particle swarm optimization. The study demonstrates that there exist optimal neighborhood decay coefficients in accordance with the regional characteristics of an area. Urban CA modelling should take into account the role of neighborhood decay. 相似文献
180.
An autonomous upwardly-moving microstructure profiler was used to collect measurements of the rate of dissipation of turbulent kinetic energy (ε) in the tropical Indian Ocean during a single diurnal cycle, from about 50 m depth to the sea surface. This dataset is one of only a few to resolve upper ocean ε over a diurnal cycle from below the active mixing layer up to the air–sea interface. Wind speed was weak with an average value of ~5 m s−1 and the wave field was swell-dominated. Within the wind and wave affected surface layer (WWSL), ε values were on the order of 10−7–10−6 W kg−1 at a depth of 0.75 m and when averaged, were almost a factor of two above classical law of the wall theory, possibly indicative of an additional source of energy from the wave field. Below this depth, ε values were closer to wall layer scaling, suggesting that the work of the Reynolds stress on the wind-induced vertical shear was the major source of turbulence within this layer. No evidence of persistent elevated near-surface ε characteristic of wave-breaking conditions was found. Profiles collected during night-time displayed relatively constant ε values at depths between the WWSL and the base of the mixing layer, characteristic of mixing by convective overturning. Within the remnant layer, depth-averaged values of ε started decaying exponentially with an e-folding time of 47 min, about 30 min after the reversal of the total surface net heat flux from oceanic loss to gain. 相似文献