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901.
902.
Inland waterway transport (IWT) is the most appropriate means of transportation in the pursuit of a sustainable development strategy. The development of IWT varies per region. Public entities and institutions play an important role in the development of IWT. This paper analyses the development of IWT on the Pearl River from an institutional perspective. Chinese national fiscal reforms, land use reforms and the transfer of power from the central government to local governments impact the governance of IWT. The paper demonstrates that the privatization of inland ports was triggered by the mismatch between the objectives of IWT operators and either public objectives or market demand. This process unfolded while top-level governors did not aim for privatization. The paper shows how formal institutional changes of IWT on the Pearl River are both the result of deliberate design and a path creation in the transformation from the Chinese planned economy to the Chinese market economy. It also shows how institutional changes resulted in a dual development path (i.e. a rapid development of inland terminals but underdevelopment of inland waterways) of IWT in the Pearl River. Policy recommendations are provided based on the research findings with specific attention to the factors hindering IWT development on the Pearl River at the level of the waterway infrastructure and inland ports. 相似文献
903.
The seismic performance of a tailings impoundment can be adversely affected by the behavior of the retained tailings. However, there remains considerable uncertainty in tailings liquefaction analysis. Twenty cyclic simple shear tests conducted on tailings from a gold mine in Quebec, Canada, were simulated numerically. The simulations indicated that the dynamic behavior of tailings could be modelled reasonably well, except that the weighted cyclic resistance curve of the tailings differed from that of clean sand which was used to develop the constitutive model (UBCSAND). An (N1)60-CS value of 10 blows/30 cm was estimated for the tailings based on calibration at a CSR of 0.10 for 15 cycles of loading. Numerical simulation of the behavior of a 20-m-high deposit of tailings during an earthquake (Mw = 5.9) indicated liquefaction of the upper 8 m of tailings. Liquefaction analysis using the Simplified method with published magnitude scaling factors (MSF) did not predict the occurrence of liquefaction. The use of MSF values calculated from the laboratory testing predicted liquefaction in the upper 8 m of tailings, corresponding quite well with the numerical simulation. The results indicate that both analytical and numerical methods can be used to evaluate the potential for tailings liquefaction under seismic loads. 相似文献
904.
Grilli Stéphan T. Shelby Mike Kimmoun Olivier Dupont Guillaume Nicolsky Dmitry Ma Gangfeng Kirby James T. Shi Fengyan 《Natural Hazards》2017,86(1):353-391
Natural Hazards - We perform numerical simulations to assess how coastal tsunami hazard from submarine mass failures (SMFs) is affected by slide kinematics and rheology. Two types of two-layer SMF... 相似文献
905.
Josh A. Calkins George Zandt James Girardi Ken Dueker George E. Gehrels Mihai N. Ducea 《Earth and Planetary Science Letters》2010,289(1-2):145-155
The late Triassic to early Tertiary Coast Mountains Batholith (CMB) of British Columbia provides an ideal locale to study the processes whereby accreted terranes and subduction-related melts interact to form stable continental crust of intermediate to felsic composition and complementary ultramafic residuals. Seismic measurements, combined with calculated elastic properties of various CMB rock compositions, provide a window into the deep-crustal lithologies that are key to understanding the processes of continental growth and evolution. We use a combination of seismic observations and petrologic modeling to construct hypothetical crustal sections at representative locations across the CMB, then test the viability of these sections via forward modeling with synthetic seismic data. The compositions that make up our petrologic forward models are based on calculations using the free energy minimization program Perple_X to predict mineral assemblages at depth for the bulk compositions of exposed plutonic rocks collected in the study area. Seismic data were collected along two transects in west-central British Columbia: a southern line that crossed the CMB near the town of Bella Coola (near 52° N), and a northern line centered on the towns of Terrace and Kitimat (near 54° N). Along both transects, seismic receiver functions reveal high Vp/Vs ratios near the Insular/Intermontane terrane boundary and crustal thickness increasing from 26 ± 3 km to 34 ± 3 km (at the 1 sigma certainty level) from west to east across the Coast Shear Zone (CSZ). On the southern line, we observe an anomalous region of complex receiver functions and diminished Moho signals beneath the central portion of the CMB. Our petrologic and seismic profiles show that observed seismic data from much of the CMB can be well-matched in terms of crustal thickness and structure, average Vp/Vs, and amplitude of the Moho converted phase, without including ultramafic residual material in the lower crust. 相似文献
906.
Piotr A. Przybylski James G. Ogg Andrzej Wierzbowski Angela L. Coe Mark W. Hounslow John K. Wright François Atrops Erik Settles 《Earth and Planetary Science Letters》2010,289(1-2):256-272
A magnetic polarity pattern for Boreal and Sub-Boreal ammonite zones of the Upper Oxfordian to Lower Kimmeridgian was established and confirmed in four British sections, including the proposed Global Boundary Stratotype Section and Point (GSSP) on the Isle of Skye (Scotland) to define the base of the international Kimmeridgian Stage. A coeval pattern for Sub-Mediterranean ammonite zones was compiled from seven sections in Poland, one German section and multi-section composites from France and Spain. The mean paleopole for the European Craton (excluding Spain) at the Oxfordian–Kimmeridgian boundary is 74.2°N, 181.3°E (Α95 = 3.8°). The common magnetic polarity scale enables inter-correlation of ammonite subzones among these three faunal provinces and to the marine magnetic-anomaly M-Sequence. The proposed GSSP at the base of the Pictonia baylei Zone is near the base of an extended interval dominated by reversed polarity, which is interpreted to be Chron M26r. This GSSP level projects to the lower to middle part of the Epipeltoceras bimammatum Subzone, which is the middle subzone of this E. bimammatum Zone in the Sub-Mediterranean standard zonation. In contrast, the traditional placement of the Oxfordian–Kimmeridgian boundary in that Sub-Mediterranean standard zonation (base of Sutneria platynota Zone) is at the base of Chron M25r, or nearly 1 million years younger. 相似文献
907.
by James E. Landmeyer Paul M. Bradley Donald A. Trego Kevin G. Hale Joseph E. Haas II 《Ground water》2010,48(1):30-41
Groundwater contamination by fuel-related compounds such as the fuel oxygenates methyl tert -butyl ether (MTBE), tert -butyl alcohol (TBA), and tert -amyl methyl ether (TAME) presents a significant issue to managers and consumers of groundwater and surface water that receives groundwater discharge. Four sites were investigated on Long Island, New York, characterized by groundwater contaminated with gasoline and fuel oxygenates that ultimately discharge to fresh, brackish, or saline surface water. For each site, contaminated groundwater discharge zones were delineated using pore water geochemistry data from 15 feet (4.5 m) beneath the bottom of the surface water body in the hyporheic zone and seepage-meter tests were conducted to measure discharge rates. These data when combined indicate that MTBE, TBA, and TAME concentrations in groundwater discharge in a 5-foot (1.5-m) thick section of the hyporheic zone were attenuated between 34% and 95%, in contrast to immeasurable attenuation in the shallow aquifer during contaminant transport between 0.1 and 1.5 miles (0.1 to 2.4 km). The attenuation observed in the hyporheic zone occurred primarily by physical processes such as mixing of groundwater and surface water. Biodegradation also occurred as confirmed in laboratory microcosms by the mineralization of U- 14 C-MTBE and U-14 C-TBA to 14 CO2 and the novel biodegradation of U- 14 C-TAME to 14 CO2 under oxic and anoxic conditions. The implication of fuel oxygenate attenuation observed in diverse hyporheic zones suggests an assessment of the hyporheic zone attenuation potential (HZAP) merits inclusion as part of site assessment strategies associated with monitored or engineered attenuation. 相似文献
908.
Antifouling paint fragments collected from marinas and leisure boat maintenance facilities and in the vicinity of abandoned boats have been chemically characterised. High concentrations of Cu (23-380 mg g−1) and Zn (14-160 mg g−1) in the samples (n = 14) are consistent with the use of these metals in the principal biocidal and non-biocidal pigments in contemporary antifouling formulations. Up to about 2% and 7% of the respective metals were solvent-extractable, suggesting that organo-forms of Cu and Zn (e.g. pyrithiones) were also present. Of the organic biocides, dichlofluanid was present in most samples and at concentrations up to about 20 mg g−1. Chlorothalonil and Irgarol 1051® were only detected in one and four cases, respectively, and Sea Nine 211® was not detected in any sample. Results are discussed in terms of UK legislation regarding biocide usage and the likely effects and fate of discarded paint particles in coastal environments where boats are repaired or moored. 相似文献
909.
A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8-30.1 °C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress. 相似文献
910.
We employ a computationally efficient fault system earthquake simulator, RSQSim, to explore effects of earthquake nucleation and fault system geometry on earthquake occurrence. The simulations incorporate rate- and state-dependent friction, high-resolution representations of fault systems, and quasi-dynamic rupture propagation. Faults are represented as continuous planar surfaces, surfaces with a random fractal roughness, and discontinuous fractally segmented faults. Simulated earthquake catalogs have up to 106 earthquakes that span a magnitude range from ~M4.5 to M8. The seismicity has strong temporal and spatial clustering in the form of foreshocks and aftershocks and occasional large-earthquake pairs. Fault system geometry plays the primary role in establishing the characteristics of stress evolution that control earthquake recurrence statistics. Empirical density distributions of earthquake recurrence times at a specific point on a fault depend strongly on magnitude and take a variety of complex forms that change with position within the fault system. Because fault system geometry is an observable that greatly impacts recurrence statistics, we propose using fault system earthquake simulators to define the empirical probability density distributions for use in regional assessments of earthquake probabilities. 相似文献