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81.
Panno SV Hackley KC Hwang HH Greenberg SE Krapac IG Landsberger S O'Kelly DJ 《Ground water》2006,44(2):176-187
Elevated concentrations of sodium (Na+) and chloride (Cl-) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br), and iodide (I) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I and Br; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources. 相似文献
82.
Earthquake simulation tests were conducted on a 1 : 15‐scale 25‐story building model to verify the seismic performance of high‐rise reinforced‐concrete flat‐plate core‐wall building structures designed per the recent seismic code KBC 2009 or IBC 2006. The following conclusions can be drawn from the test results: (1) The vertical distribution of acceleration during the table excitations revealed the effect of the higher modes, whereas free vibration after the termination of the table excitations was governed by the first mode. The maximum values of base shear and roof drift during the free vibration are either similar to or larger than the values of the maximum responses during the table excitation. (2) With a maximum roof drift ratio of 0.7% under the maximum considered earthquake in Korea, the lateral stiffness degraded to approximately 50% of the initial stiffness. (3) The crack modes appear to be a combination of flexure and shear in the slab around the peripheral columns and in the coupling beam. Energy dissipation via inelastic deformation was predominant during free vibration after the termination of table excitation rather than during table excitation. Finally, (4) the walls with special boundary elements in the first story did not exhibit any significant inelastic behavior, with a maximum curvature of only 21% of the ultimate curvature, corresponding to an ultimate concrete compressive strain of 0.00638 m/m intended in the displacement‐based design approach. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
83.
This paper reports the results of cyclic loading tests performed on four specimens consisting of reinforced concrete frames with brick infill walls. The brick infill is pre‐laid, followed by the cast in‐place RC columns and beams. Test parameters include the height‐to‐length ratio of the brick infill wall and the mortar compressive strength. Test results reveal that the in‐plane lateral strength of brick infill wall is related to the fracture path. The fracture path for brick infill walls with large height‐to‐length ratios includes bed joints, cross joints, and vertical splitting of bricks. As a result, the lateral strength of this type of brick infill wall is larger. In comparison, the fracture path for brick infill walls with small height‐to‐length ratios only passes through joints, which is the reason why they have lower lateral strength. Mortar with higher strength improves the lateral strength of brick infill wall. In addition to presenting experimental observations in detail, this paper compares the test results with those obtained from existing methods for assessment of seismic resistance. Comments and recommendations are offered with respect to the capabilities of the assessment methods in predicting stiffness, strength, and ultimate deformation capacity of brick infill walls. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
84.
85.
Let {Z(s):s∈D⊆ℝ
d
} be a zero mean stationary random field observed at a finite number of locations. Lahiri (Sankhya Ser. A 65:356–388, 2003) proved spatial central limit theorems (CLT) for ∑
i=1
n
Z(s
i
) assuming a ‘nearly infill domain sampling’. Applications of his results depended on the underlying spatial sampling region
and the design in a complicated fashion. The main objective of this paper is to provide CLTs that could be applied easily
in practice. We present two main results assuming a ‘nearly infill domain sampling’ defined mainly in terms of dependence.
Theorem 1 establishes a CLT for ∑
i=1
n
Z(s
i
) and Theorem 2 is obtained mainly for applications to density estimates. We report on a simulation study for illustrating
a way of applying our results in practice. 相似文献
86.
To investigate the impact of various types of data on medium-range forecasts, observing system experiments are performed using an assimilation algorithm based on the National Centers for Environmental Prediction (NCEP)/Department of Energy (DOE) reanalysis system. Data-denial experiments for radiosonde, satellite, aircraft, and sea surface observations, and selected data experiments for radiosonde and surface data, are conducted for the boreal summer of 1997 and the boreal winter of 1997/1998. The data assimilation system used in this study is remarkably dependent on radiosonde data, which provides information about the three-dimensional structure of the atmosphere. As expected, the impact of radiosonde observations on medium-range forecasts is strongly positive over the Northern Hemisphere and tropics, whereas the satellite system is most beneficial over the Southern Hemisphere. These results are also found in experiments simulating historical changes in observation systems. Over the tropics, assimilation without radiosonde observations generates unbalanced analyses resulting in unrealistic forecasts that must be corrected by the forecast model. Forecasts based on analysis from the observation data before the era of radiosonde observation are found to be less meaningful. In addition, the impacts on forecasts are closely related to the geographical distribution of observation data. The memory of observation data embedded in the analysis tends to persist throughout forecasts. However, cases exist where the effect of forecast error growth is more dominant than that of analysis error, e.g., over East Asia in summer, and where the deficiency in observations is supplemented or the imbalance in analysis is adjusted by the forecast model during the period of forecasts. Forecast error growth may be related to the synoptic correction performed by the data assimilation system. Over data-rich areas, analysis fields are corrected to a greater extent by the data assimilation system than are those over data-poor areas, which can cause the forecast model to produce more forecast errors in medium-range forecasts. It is found that even one month per season is sufficient for forecast skill verification in data impact experiments. Additionally, the use of upper-air observations is found to benefit areas that are downstream of observation data-rich areas. 相似文献
87.
Coastal Gravity Anomalies from Retracked Geosat/GM Altimetry: Improvement, Limitation and the Role of Airborne Gravity Data 总被引:6,自引:0,他引:6
Cheinway Hwang Jinyun Guo Xiaoli Deng Hsin-Ying Hsu Yuting Liu 《Journal of Geodesy》2006,80(4):204-216
We process geophysical and waveform data records of the Geosat/GM (geodetic mission) satellite altimeter mission for waveform retracking and applications. An improved threshold retracker is developed. The performances of the Beta-5, threshold and improved threshold retrackers are assessed over waters around Taiwan. The improved threshold retracker outperforms the other two. The improvement in the accuracy of sea surface height (SSH) is investigated according to marine zone and the distance of waters to the shore. The improvement rate increases closer to the land, with the largest improvement rate of about 20% in waters within 10 km of the shore. Over waters around islands and coasts, there are still retracked SSHs with large errors. Least-squares collocation is used to compute gravity anomalies from the Geosat/GM altimeter data. Use of retracked SSHs improves the accuracy of gravity anomalies by about 11%. Adding airborne gravity data further improves the accuracy, especially in the immediate vicinity of the coasts. Tide model errors over coastal waters remain a problem in altimetry applications, even if the waveforms are properly retracked. 相似文献
88.
Shyh-Lung Hwang Tzen-Fu Yui Hao-Tsu Chu Pouyan Shen Ru-Yuan Zhang Juhn G. Liou 《Contributions to Mineralogy and Petrology》2011,161(6):901-920
Optical microscopy, secondary electron microscopy and analytical electron microscopy were used to characterize crystallographic
orientation relationships between oriented mineral inclusions and clinopyroxene (Cpx) host from the Hujialing garnet clinopyroxenite
within the Sulu ultrahigh-pressure (UHP) terrane, eastern China. One garnet clinopyroxenite sample (2HJ-2C) and one megacrystic
garnet-bearing garnet clinopyroxenite (RZ-11D) were studied. Porphyroblastic clinopyroxene from sample 2HJ-2C contains oriented
inclusions of ilmenite (Ilm), spinel (Spl), magnetite and garnet, whereas clinopyroxene inclusions within megacrystic garnet
from sample RZ-11D contain oriented inclusions of ilmenite and amphibole. Specific crystallographic relationships were observed
between ilmenite/spinel plates and host clinopyroxene in sample 2HJ-2C and between ilmenite plates and host clinopyroxene
in sample RZ-11D, i.e. [1[`1]00 1\bar{1}00 ]Ilm//[0[`1]0 0\bar{1}0 ]Cpx (0001)Ilm//(100)Cpx; and [110]Spl//[0[`1]0 0\bar{1}0 ]Cpx ([`1]11 \bar{1}11 )Spl//(100)Cpx. These inclusions are suggested to be primary precipitates via solid-state exsolutions. Most of the needle-like magnetite/spinel
inclusions generally occur at the rims or along fractures of clinopyroxene within sample 2HJ-2C. Despite the epitaxial relation
with host clinopyroxene, these magnetite/spinel needles would have resulted from fluid/melt infiltrations. Non-epitaxial garnet
lamellae in clinopyroxene of sample 2HJ-2C were formed via fluid infiltration-deposition primarily along (010) and subordinately
along (100) partings. Epitaxial amphibole plates (with a thickness <1 μm) and lamellae (with a thickness = 1–10 μm) in host
clinopyroxene of sample RZ-11D were probably results of hydration processes, although amphibole plates could otherwise be
interpreted as exsolution products. Temporal relations between mineral inclusions in each sample can be established, and a
semi-quantitative P–T path for this garnet clinopyroxenite body was derived accordingly. The present results show that the
Hujialing garnet clinopyroxenite may not have subducted to mantle depths as deep as 250 km during UHP metamorphism as suggested
by previous studies. This study demonstrates that the crystallographic and temporal/spatial relationships between aligned
inclusions and host minerals are essential to a correct genetic interpretation of metamorphic rocks. 相似文献
89.
木文从分析气象回波涨落的原因入手,讨论了视频积分处理器参数的选择。从现有硬件实现的数字视频积分器,引导出以全软件实现数字视频积分器的方案。实践证明,软件数字视频积分器与硬件数字视频积分器具有同样的功能,并且具有开发灵活、适用性强的特。点该处理器已经应用在713天气雷达数字化系统中。 相似文献
90.
西南极利文斯顿岛百耳斯半岛中生代火山岩地球化学特征 总被引:1,自引:0,他引:1
西南极利文斯顿岛百耳斯半岛中生代火山岩是晚侏罗纪至晚白垩纪三期火山活动的产物。岩石普遍贫钾,轻稀土元素略为富集,但轻重稀土分馏不强烈;Sr、K、Rb、Ba、Th等大离子亲石元素(LIL)明显富集,Nb和Ta明显亏损,过渡金属族元素Cr和Ni强烈亏损,表明它们属于火山弧环境中生成的钙碱性系列岩石。白垩纪中期和白垩纪晚期岩石的87Sr/86Sr比值主要在0.7039~0.7053之间变化,εNd>0,87Sr/86Sr相对1/Sr、Rb、K和SiO2等的变化不大,表明其源区岩浆可能直接来自上地幔,很少受到壳源物质的混染。而晚侏罗纪火山岩的Sr同位素比值较高,说明早期岩浆可能受到少量地壳物质的混染。但在Th/Ta-Th和Th/Sm-Th图解上所有岩石的投影点分布趋势相同,趋势线的斜率>0。百耳斯半岛中生代火山岩是上地幔部分熔融生成的同源岩浆不同期的产物 相似文献