Petrologic and geochemical constraints on the petrogenesis of Permian–Triassic Emeishan flood basalts in southwestern China     

Yigang Xu  Sun-Lin Chung  Bor-ming Jahn  Genyao Wu 《Lithos》2001,58(3-4):145-168

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A three-stage identification approach for hysteretic systems     

Chin-Hsiung Loh  Sheng-Tsai Chung 《地震工程与结构动力学》1993,22(2):129-150

This paper deals with the identification of the parameters of a smoothed hysteretic model which was proposed by Bouc and Wen with emphasis on restoring force hysteresis. The problem of estimating the parameters of this system on the basis of input-output data, possibly noise corrupted, is considered. Through the application of various simulated time histories from the hysteretic model, a three-stage systematic method of system identification was proposed. Four different methods of identification are arranged and conducted in this three-stage system identification. The first stage, a sequential regressional analysis is used to identify the equivalent linear system from which elastic or inelastic response can be identified. The identified parameters can be used in the stage when the system is in elastic response. In the second stage, both time domain least-squares method and Gauss-Newton method are applied. The convergence of the Gauss-Newton method can be guaranteed if the identified results from least-squares method are adopted as the initial values for Gauss-Newton method. In the third stage, the extended Kalman filtering technique is needed to identify the noise-corrupt data. Application of this algorithm to a SDOF non-deteriorating system is verified.  相似文献   

Radium and barium at GEOSECS stations in the Atlantic and Pacific     

L.H. Chan  J.M. Edmond  R.F. Stallard  W.S. Broecker  Y.C. Chung  R.F. Weiss  T.L. Ku 《Earth and Planetary Science Letters》1976,32(2):258-267

²²⁶Ra and Ba show a general linear correlation in the oceanic water column within the uncertainties of the data: the slope of the line is about 4.6 nanomoles (nmoles) Ra/mole Ba, the intercept being at about 4 nmoles Ba/kg. This demonstrates the usefulness of Ba as a “chemical analogue” of Ra. Box-model calculations indicate that the average deep-water excess of Ra over Ba should be about 10% relative to the surface. This is consistent with the observations outside the deep northeast Pacific. However, the uncertainties in the data are such that the regional variation in the primary input cannot be resolved. In the deep waters of the North Pacific there is in fact a large excess of Ra relative to Ba. The one detailed profile presently available (204) can be explained consistently by a simple vertical advection-diffusion model.  相似文献   

Carbon isotope geochemistry of Paleozoic oils from Big Horn Basin     

H.Moses Chung  Sheri W. Brand  Patrick L. Grizzle 《Geochimica et cosmochimica acta》1981,45(10):1803-1815

Twenty crude oils from Paleozoic reservoirs in the Big Horn Basin. Wyoming were fractionated into light hydrocarbons, saturates, monoaromatics. diaromatics, polyaromatics-and-polars. and asphaltenes. Amounts and isotopic composition of each fraction were found to be internally consistent with the degree of maturation of the oil. confirming the established single source origin for these oils. A variation of approximately three per mil in the carbon isotopic composition of the whole oil and individual fraction was explained as being caused by maturation. The isotope-type-curves for these oils, the variations in isotopic composition as a function of compound group-type, were not found to be as simple as commonly believed. Other alteration processes, such as migration and deasphalting, might have influenced the pattern of the isotope distributions among fractions. The conservative nature of mass balance and subsequent isotope flows among various fractions of crude oil showed that the maturation of crude oil consists of consecutive processes leading from larger and more polar components into smaller and less polar components culminating in natural gas. Calculations were made to project the amount of condensates associated with the crude oils, and the amount of natural gas which had been generated from crude oils of a given maturity.  相似文献   

Regression models for estimating mineral resources from geological map data   总被引：9，自引：0，他引：9  

C. F. Chung  F. P. Agterberg 《Mathematical Geology》1980,12(5):473-488

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²²⁶Ra in the Pacific Ocean     

Y. Chung  H. Craig 《Earth and Planetary Science Letters》1980,49(2):267-292

A total of 29 vertical Ra profiles has been measured from the Pacific as part of the GEOSECS program. These profiles are located on an east-west section along ～30°N, and a north-south section, close to the western boundary of the major basins in the western Pacific. Profiles from the northeast Pacific show a deep Ra maximum, with an excess concentration relative to the potential temperature and salinity. This maximum extends westward in the direction with decreasing Ra content, and finally vanishes completely in the northwest Pacific near Japan.Ra profiles along the western boundary show a mid-depth maximum around 3 km and a near-bottom minimum due to southward intrusion of the high-Ra Pacific Deep Water and a northward spreading of the low-Ra Antarctic Bottom Water. The contrast between the maximum and the minimum intensifies toward the south, where the benthic front has clearly separated these two water masses. Ra is thus a useful tracer for the studies of oceanic mixing and circulation in the Pacific.  相似文献   

²²⁶Ra,²¹⁰Pb and²¹⁰Po in the Red Sea     

Y. Chung  R.C. Finkel  K. Kim 《Earth and Planetary Science Letters》1982,58(2):213-224

Profiles of²²⁶Ra and dissolved²¹⁰Pb have been measured at several stations in the Red Sea. At one station in the central Red Sea an expanded profile was measured including²²⁶Ra and dissolved and particulate²¹⁰Pb and²¹⁰Po. These profiles show several distinct features: (1)²²⁶Ra displays a mid-depth maximum of about 13 dpm/100 kg at about 500 m; (2) dissolved²¹⁰Pb concentrations are uniformly low at about 2 dpm/100 kg with little lateral or vertical variation; (3) the surface-water²¹⁰Pb excess which is commonly observed in low-latitude open ocean regions is entirely lacking; (4)²¹⁰Pb and²¹⁰Po activities are essentially identical to each other in both particulate and dissolved phases although²¹⁰Po activities appear somewhat lower; (5) about 20% of the²¹⁰Pb and²¹⁰Po in the water column residues on particulate matter.Assuming the atmospheric²¹⁰Pb flux to be in the dissolved form and at the lower level of the normal range i.e. 0.5 dpm/cm² yr, the residence time of the dissolved Pb is about 1.5 years. However, if the same atmospheric flux is entirely in particulate form, then the residence time of the dissolved Pb is about 5 years. The residence time of Pb in the particulate phase is less than 0.4 years if all the Pb is removed only by sinking particles.  相似文献   

A carbon inventory for Orca Basin brines and sediments     

W.M. Sackett  J.M. Brooks  B.B. Bernard  C.R. Schwab  H. Chung  R.A. Parker 《Earth and Planetary Science Letters》1979,44(1):73-81

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STARTER: a statistical GIS-based model for the prediction of snow avalanche susceptibility using terrain features—application to Alta Val Badia, Italian Dolomites   总被引：1，自引：0，他引：1  

Alessandro Ghinoi  Chang-Jo Chung   《Geomorphology》2005,66(1-4):305

This article describes a methodology to localise areas with high potential towards natural snowpack instability under particular meteorological conditions, at the scale of an Alpine valley. Localisation is based on statistically relating known release areas of past avalanche events to maps of: (1) slope inclination, (2) slope orientation (aspect), (3) elevation, (4) distance from crest lines, (5) terrain roughness and (6) concavities/convexities. The maps have been built using two different GIS softwares while the statistical analyses have been performed with a specific software handling also Fuzzy Set theory algorithms. The results of the statistical analyses have been verified on test release—areas which have not been used as input data for the statistical analyses. Verification allowed to quantify how reliably the susceptibility values were calculated, to compare the values obtained using different combinations of terrain features and to finally decide on the most efficient combination. The susceptibility maps were calculated and verified for three different meteorological scenarios (given by three classes of snow depth). Verification has shown that the accuracy of the susceptibility maps was between 67% and 82%. The three susceptibility maps show a remarkable difference in the spatial pattern of the highest susceptibility pixels suggesting that for different meteorological scenarios different classes of terrain features need to be considered.The possibility to make combinations of terrain features and to assess and verify their statistical relationship with release areas of past avalanche events is the major original step made by STARTER. Linking those release areas to meteorological scenarios is an attempt to include in the analysis the combined influence of terrain features and meteorological conditions towards snowpack instability.  相似文献   

On Climate Variations and Changes Observed in South Korea   总被引：1，自引：0，他引：1  

Yong-Seung Chung  Ma-Byung Yoon  Hak-Sung Kim 《Climatic change》2004,66(1-2):151-161

This study describes observations on possible climate changes occurring on the Korean Peninsula. We found that in large urban and industrial areas in Korea, there has been a significant increase in the annual mean temperatures according to data of the past 29 years. The increase in January temperatures was in the order of 0.8 ～ 2.4 ° C. However, in rural and marine stations, the increase in annual mean temperature was 0.6 ° C; the level of the global average. There was also an increase in precipitation: 259 mm over the recent 97 years. Observation has revealed that a month-long steady rainfall in late June and July with a quasi-stationary polar front has not occurred in recent years and has been replaced with scattered convective heavy-showers on a local scale in July and August. It is observed that the behaviour of this rainy front, `the Changma front' has brought changes to rainfall characteristics. Our results highlight the importance of the shortened rainy season. However, the amount of rainfall and the number of heavy rainfall days have increased.  相似文献