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561.
562.
A scenario for the future development of the Dutch Wadden Sea is derived from an evolutionary model for tidal basins during a rise in sea level. The model is based on the evolution of the Atlantic/Subboreal Holland tidal basin, between 7000 BP and 3500 BP. It emphasizes the balance between the storage capacity created by a sea-level rise and the amount of sediment available.
If the rate of relative sea-level rise exceeds the rate of sediment supply, the innermost (central) portions of the basin will not receive sufficient sediment for an intertidal morphology to be preserved. Eventually, sand will be deposited only in tidal channels and in the flood-tidal delta through which the sediment is supplied, mud deposition will occur in the interchannel areas and salt marshes will disappear. 相似文献
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Tesfahun Berhane Nurilign Shibabaw Aemiro Shibabaw Molalign Adam Abera A. Muhamed 《资源与生态学报(英文版)》2018,9(3):302-305
Ethiopian coffee price is highly fluctuated and has significant effect on the economy of the country. Conducting a research on forecasting coffee price has theoretical and practical importance.This study aims at forecasting the coffee price in Ethiopia. We used daily closed price data of Ethiopian coffee recorded in the period 25 June 2008 to 5 January 2017 obtained from Ethiopia commodity exchange (ECX) market to analyse coffee prices fluctuation. Here, the nature of coffee price is non-stationary and we apply the Kalman filtering algorithm on a single linear state space model to estimate and forecast an optimal value of coffee price. The performance of the algorithm for estimating and forecasting the coffee price is evaluated by using root mean square error (RMSE). Based on the linear state space model and the Kalman filtering algorithm, the root mean square error (RMSE) is 0.000016375, which is small enough, and it indicates that the algorithm performs well. 相似文献
566.
Tesfahun Berhane Nurilign Shibabaw Aemiro Shibabaw Molalign Adam Abera A.Muhamed 《资源与生态学报(英文版)》2018,(3)
埃塞俄比亚咖啡价格波动很大,因此对国家经济发展的影响不容小视,对咖啡价格进行预测具有理论和实践意义。为了分析咖啡价格波动,我们采用来自埃塞俄比亚商品交易所(ECX)记录的2008年6月25日至2017年1月5日期间咖啡日收盘价数据。在这里,咖啡价格的性质是非平稳的,我们在单个线性状态空间模型上应用卡尔曼滤波算法来预测咖啡价格的最优值,主要通过使用均方根误差(RMSE)来评估用于预测咖啡价格的算法的性能。基于线性状态空间模型和卡尔曼滤波算法,均方根误差(RMSE)为0.000016375,说明该算法性能良好,研究结果可靠。 相似文献
567.
This article presents the rationale for the need to take into account and assess natural capital as an important factor for viable managerial decision-making concerning the study, use and reproduction of natural resources in the interests of sustainable development. The activity of authorities in Tomsk oblast was used as an example in examining the issues related to integration of accounting and assessing natural capital and ecosystem services in the system of managerial decision-making. We used strategic and normative documents of Tomsk oblast, departmental information and material from previous research into assessments of natural capital. A rationale is given for the need to improve the institutional conditions for proper inventory and assessment of all functions of natural capital and ecosystems in managerial decision-making, namely the development of the monitoring system for economic value in the sphere of environmental management which is based on the system of ecological-economic accounting and constitutes a set of coherent statistical indicators reflecting the status of natural capital. The mechanism is suggested for generation of the information-methodological base of economic assessment of natural capital. It is determined that a qualitatively new information basis integrated into the system of regional management. Qualitatively new information basis integrated into the regional government system will make it possible not to simply obtain information on the flows of expenditures and benefits in the sphere of environmental management but also to ensure interaction between state and municipal authorities and with organizations and the population. The monitoring system for economic value of natural capital and ecosystem services integrated into the region’s executive bodies will permit adaptive governance of environmental management of the region in the face of changes and uncertainty. 相似文献
568.
ABSTRACTAll states, whether governed by liberal or illiberal regimes, face the prospect of momentous and potentially catastrophic environmental impacts due to climate change. Historically, energy policy has been directed towards simply achieving energy security. This goal has now been significantly complicated by the need to achieve it while minimizing greenhouse gas emissions. Environmental non governmental organizations (ENGOs) could play a crucial role in promoting the transition to energy and climate security but the relative (il)liberalism of the political regime they operate under influences their effectiveness. This article assesses how ENGOs have impacted on the transition to energy and climate security in Myanmar and Thailand, two Southeast Asian countries highly susceptible to climate impacts and characterized by illiberal rule. It finds that the impact of ENGOs was highly dependent on their strategies, tactics and operation, with community-level projects providing a key route to effect change under conditions of extreme illiberalism. 相似文献
569.
Large power transformers (LPTs) are critical yet vulnerable components of the power grid. More frequent and intense heat waves or high temperatures can degrade their operational lifetime and increase the risk of premature failure. Without adequate preparedness, a widespread situation could ultimately lead to prolonged grid disruption and incur excessive economic costs. Here, we investigate the potential impact of climate warming and corresponding shifts in summertime “hot days” on a selected LPT located in the Northeast United States. We apply an analogue method, which detects the occurrence of hot days based on the salient, associated large-scale atmospheric conditions, to assess the risk of future change in their occurrence. Compared with the more conventional approach that relies on climate model-simulated daily maximum temperature, the analogue method produces model medians of late twentieth century hot day frequency that are more consistent with observation and have stronger inter-model consensus. Under the climate warming scenarios, multi-model medians of both model daily maximum temperature and the analogue method indicate strong decadal increases in hot day frequency by the late twenty-first century, but the analogue method improves model consensus considerably. The decrease of transformer lifetime with temperature increase is further assessed. The improved inter-model consensus of the analogue method is viewed as a promising step toward providing actionable information for a more stable, reliable, and environmentally responsible national grid. 相似文献
570.
The partitioning of silver in a sulfur-free rhyolite melt-vapor-brine assemblage has been quantified at 800 °C, pressures of 100 and 140 MPa and fO2≈NNO (nickel-nickel oxide). Silver solubility (±2σ) in rhyolite increases 5-fold from 105 ± 21 to 675 ± 98 μg/g as pressure increases from 100 to 140 MPa. Nernst-type partition coefficients describing the mass transfer of silver at 100 MPa between vapor and melt, brine and melt and vapor and brine are 32 ± 30, 1151 ± 238 and 0.026 ± 0.004, respectively. At 140 MPa, values for for vapor and melt, brine and melt, and vapor and brine are 32 ± 10, 413 ± 172 and 0.06 ± 0.03, respectively. Apparent equilibrium constant values (±2σ) describing the exchange of silver and sodium between vapor and melt, , at 100 and 140 MPa are 105 ± 68 and 14 ± 6. The average values (±2σ) for silver and sodium exchange between brine and melt, , at 100 and 140 MPa are 313 ± 288 and 65 ± 12. These data indicate that the mass transfer of silver from rhyolite melt to an exsolved volatile phase(s) is enhanced at 100 MPa relative to 140 MPa, suggesting that decompression increases the silver ore-generative potential of an evolving silicate magma. Model calculations using the new data suggest that the evolution of low-density, aqueous fluid (i.e., vapor) may be responsible for the the silver tonnage of many porphyry-type and perhaps epithermal-type ore deposits. For example, Halter et al. (Halter W. E., Pettke T. and Heinrich C. A. (2002) The origin of Cu/Au ratios in porphyry-type ore deposits. Science296, 1842-1844) used detailed silicate and sulfide melt inclusion and vapor and brine fluid inclusions analyses to estimate a melt volume on the order of 15 km3 to satisfy the copper budget at the Bajo de la Alumbrera copper-, gold-, silver-ore deposit. Using their melt volume estimate with the data presented here, model calculations for a 15-km3 felsic melt, saturated with pyrrhotite and magnetite, suggest that a low-salinity magmatic vapor may scavenge on the order of 7 × 1012 g of silver from the melt. This quantity of silver exceeds the discovered 2 × 109 g of Ag at Alumbrera. Calculated tonnages for numerous other deposits yield similar results. The excess silver in the vapor, remaining after porphyry formation, is then available to precipitate at lower PTconditions in the stratigraphically higher epithermal environment. These data suggest that silver, and perhaps other ore metals, in the porphyry-epithermal continuum may be derived solely from the time-integrated flux of dominantly low-salinity vapor exsolved from a series of sequential magma batches. 相似文献