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211.
A genetic algorithm was used to optimize the parameters of the two-dimensional Storm Surge/Tide Operational Model (STORM) to improve sea level predictions.The genetic algorithm was applied to nine typhoons that affected the Korean Peninsula during 2005-2007.The following model parameters were used:the bottom drag coefficient,the background horizontal diffusivity,Smagorinski’s horizontal viscosity,and the sea level pressure scaling.Generally,the simulation results using the optimized,mean,and median parameter values improved sea level predictions.The four estimated parameters improved the sea level prediction by 76% and 54% in the bias and root mean square error for Typhoon Kalmaegi (0807) in 2008,respectively.One-month simulations of February and August 2008 were also improved using the estimated parameters.This study demonstrates that parameter optimization on STORM can improve sea level prediction. 相似文献
212.
Correlation assessment and monitoring of the potential pollutants in the surface sediments of Pyeongchang River, Korea 总被引:1,自引:0,他引:1
The study provides a baseline for the assessment of the organic and inorganic pollution specially, heavy metal contamination in the surface sediments of Pyeongchang River,South Korea.The assessment of the study areas was done with respect to metal pollution load,ecological risk and geoaccumulated risk.Based upon the used indices,a priority index(Pindex) was used to rank the utmost contaminated sites.Though the concentrations of mercury in all sediments were below the guideline, the significant enriched contamination was observed by all applied indices.As expected,the values of pollution load index(PLI),ecological risk index(RI) and geoaccumulation risk index(Igeo) demonstrated lower heavy metal contamination in upstream areas compared to the downstream. Admittedly,sediments were unpolluted to slightly-polluted according to PLI while high to extremely high ecological risks were observed in several sediment samples.Furthermore,all the samples were uncontaminated as per Igeo.After simplification of Igeo,the Pindex,showed the utmost contaminated sediments with a value of 2.537.Notably,protective measures should be taken to the highly contaminated areas which are prioritized by Pindex Admittedly,the maximum concentrations of total organic carbon,total nitrogen,inorganic nitrogen,total phosphorous,inorganic phosphorous,calcium, magnesium,sodium and potassium were significantly observed as 7.8×104,3,185,36,1,032,3.7, 1,5163,2,881,669 and 4,076mg/kg accordingly. 相似文献
213.
David W. MITTLEFEHLDT Andrew W. BECK Cin‐Ty A. LEE Harry Y. McSWEEN Jr. Paul C. BUCHANAN 《Meteoritics & planetary science》2012,47(1):72-98
Abstract– We have done bulk rock compositional analyses (INAA, ICP‐MS) and petrologic study of a suite of diogenite meteorites. Most contain orthopyroxenes with mg#s of 70.6–79.0. Meteorite Hills (MET) 00425 is magnesian (mg# of 83.9). Lewis Cliff (LEW) 88011 contains orthopyroxene grains of varying mg# (76.3–68.6). Queen Alexandra Range (QUE) 93009 (orthopyroxene mg# 70.6) contains coarse‐grained noritic clasts (plagioclase An84.7–88.3), and is rich in incompatible trace elements. It has Eu/Eu* < 1, indicating that cumulate norites do not dominate its trace element inventory. Queen Alexandra Range 93009 may be transitional between diogenites and magnesian cumulate eucrites. Lewis Cliff 88679, a dimict breccia of harzburgite and orthopyroxenite, has anomalously low concentrations of highly incompatible elements (e.g., Nb, La, Ta, U) compared to other diogenites, but is similar to them in less highly incompatible elements (e.g., Y, Zr, Yb, Hf). It is unlikely that this characteristic reflects a low proportion of a trapped melt component. The highly incompatible elements were likely mobilized after impact mixing of the two parent lithologies. Graves Nunataks 98108 shows an extreme range in Eu/Eu* attributable to the heterogeneous distribution of plagioclase; one sample has the lowest Eu/Eu* among diogenites. We find no compelling evidence to support the hypothesis that diogenite parent magmas were contaminated by partial melts of the eucritic crust. We posit that subsolidus equilibration between orthopyroxene and minor/trace phases (including phosphates) resulted in preferential redistribution of Eu2+ relative to Eu3+ and other rare earth elements, and results in anomalously low Eu/Eu* in samples leached in acids that dissolve phosphates. 相似文献
214.
圆弧形沉积谷地对平面P波的三维散射解析解 总被引:5,自引:0,他引:5
采用大圆弧面来模拟半空间表面,利用波函数展开法在频域内给出了圆弧形沉积谷地形对平面P波三维散射的一个解析解,并以此解答为基础,进一步分析了入射波频率和入射角度对圆弧形沉积谷地场地反应的影响。数值结果表明,入射波的频率和入射角度对圆弧形沉积谷地场地反应有重要影响。 相似文献
215.
李旭辉 《资源与生态学报(英文版)》2010,1(1):87-93
这一评述总结2008年耶鲁大学中国的环境和资源利用问题研讨会的讨论重点,包括:1)保护地方利益和防止污染扩散的区域协调;2)建立环境特殊区,实行前瞻性的环境政策试验;3)加强环境和资源利用教育和能力建设;4)协调国内和国际环境合作关系;5)中国的环境决策中权力的制约与平衡。本文不打算对这些专题进行深入分析,而是强调西方环境管理经验和教训与中国的现实相结合的重要性。 相似文献
216.
Der‐Chuen LEE 《Meteoritics & planetary science》2008,43(4):675-684
Abstract— An acapulcoite, Northwest Africa (NWA) 725, a transitional acapulcoite, Graves Nunataks (GRA) 95209, and a lodranite, NWA 2235, have been studied with the short‐lived chronometer 182Hf‐182W system in order to better constrain the early evolution history in the acapulcoite‐lodranite parent body. Unlike the more evolved achondrites originating from differentiated asteroids—e.g., eucrites and angrites—bulk rock acapulcoites and lodranite are characterized by distinct 182W deficits relative to the terrestrial W, as well as to the undifferentiated chondrites, εw varies from ?2.7 to ?2.4. This suggests that live‐182Hf was present during the formation of acapulcoites and lodranites, and their parent body probably had never experienced a global melting event. Due to the large uncertainties associated with the isochron for each sample, the bulk isochron that regressed through the mineral separates from all 3 samples has provided the best estimate to date for the timing of metamorphism in the acapulcoite‐lodranite parent body, 5 (+6/‐5) Myr after the onset of the solar system. It is thus inconclusive whether acapulcoites and lodranites have shared the same petrogenetic origin, based on the Hf‐W data of this study. Nevertheless, the formation of acapulcoite‐lodranite clan appears to have post‐dated the metal‐silicate segregation in differentiated asteroids. This can be explained by a slower accretion rate for the acapulcoite‐lodranite parent body, or that it had never accreted to a critical mass that could allow the metal‐silicate segregation to occur naturally. 相似文献
217.
2009年8月8日莫拉克台风重创南台湾,嘉义阿里山区72 h的累积雨量高达2 500 mm以上,百年历史的阿里山森林铁道因沿线路基严重流失而停驶。其中两处大崩塌路段的复建工程以顺应自然为原则,采取迂回隧道方式避开崩塌区,需克服沿线地质变化及地下水问题,评估结果是以凿岩机工法及钻爆工法进行开挖。两座隧道的西口段崩积层分别长达109.8、99 m,是隧道开挖阶段的关键地段。隧道开挖支撑设计系依据台湾岩体分类与支撑系统(PCCR系统)及新奥工法的理念,沿线采用先进支撑材料包括超前管棚钢管、桁型钢支护、钢纤维喷射混凝土及自钻式锚杆等,除了可确保施工安全外,亦可提高施工进度。目前两隧道均已贯通且变形量控制均符合安全,说明隧道采用先进支撑方式穿越破碎崩积层段的成效良好,其研究结果可为相关工程设计提供参考。 相似文献
218.
曾文水库保护带泰山滑坡之调查与治理 总被引:1,自引:0,他引:1
崩塌与滑坡灾害之治理,首重破坏诱因了了解与破坏机制之调查。再根据调查观测所得之资料与参数,着手进行设计适当之防治对策,方能得到良好的治理成效。泰山滑坡位于台湾南部极重要之曾文水库的保护带。其边坡由陆陆续续的崩陷而逐渐演变为坍滑,甚至造成交通中断受阻。调查发现本区为属浅层滑动,滑动区平面类似酒瓶状,主要原因为长期受到雨水之漫流与渗透软化的影响,加上蚀沟之切割淘刷作用,使得边坡容易失去支撑而滑动。经施以经济有效的蚀沟控制工程兴建多座潜坝,跌水与排水设施后,发现确定提高了边坡之稳定性,地区产业因而可以持续动作,是一次相当成功的治理案例模式,但由于施工便道之开 当,遂再度诱发部份边坡的坍滑,故尔后之维护管理工作极为重要。 相似文献
219.
Storm-influenced siliciclastic and carbonate ramp deposits, the Lower Ordovician Dumugol Formation, South Korea 总被引:4,自引:0,他引:4
The Dumugol Formation (Lower Ordovician) in the southern part of the Baegunsan syncline, South Korea, contains mixed siliciclastic and carbonate ramp deposits. The ramp sediments were frequently influenced by storm events resulting in tempestites of sandstone-mudstone couplets, bioclastic grainstones to packstones, flat-pebble conglomerates, a skeletal lag layer and laminated calcisiltites. All tempestites are characterized by an erosive to sharp base, poor grading and a transitional upper boundary. The difference in lithology of tempestites appears to have been controlled by the nature of substrates and by proximality. For example, laminated calcisiltites have developed on the shallow carbonate ramp, flat-pebble conglomerates are closely associated with nodular limestones on shallow and deep ramps, and thin skeletal lag layers from fossiliferous argillaceous sediments formed in a basinal setting. The stratigraphic succession of the Dumugol Formation represents an initial transgression followed by a regression. The vertical facies change records the transition from a shallow siliciclastic ramp to a deep carbonate ramp, to a basin, shallowing to a deep carbonate ramp, and to a shallow carbonate ramp. Storm effects are mostly well preserved in shallow to deep ramp deposits. 相似文献
220.
Meitien is one of the largest villages in Ichanghsien, Hunan, and is situated about 20 km. west-southwest of the Ichang City. The well-known Chitienling (騎田嶺), one of the "Five Ranges" of the Nanling, stands on the north side of Meitien, at a distance of 相似文献