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Study on the simulation of transparency of Lake Taihu under different hydrodynamic conditions

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science china Earth sciences 2006年第z1期49卷 162-175页

作者： pANG Yong, LI Yiping & LUO Liancong College of Environmental science and Engineering, Hohai university, nanjing 210098, china nanjing institute of Geography & Limnology, Chinese Academy of sciences, nanjing 210098, china College of Environmental science and Engineering Hohai University Nanjing China nanjing institute of Geography & Limnology Chinese Academy of Sciences Nanjing China

It was indicated in this study that there were negative relations between the concentrations of suspended solid (SS) and transparency according to the analysis of measured data of Lake Taihu. Their relations in pervious studies were reviewed, which showed that the changes of transparency in Lake Taihu could be reflected by simulating suspended solid concentration (SSC). Measured data showed that the changes of SSC with wind speed were similar at different water *** increased with the increasing of wind speed. Both wave and lake current of Lake Taihu had positive relations with SSC. However, wave was the main factor affecting sediment suspension, while flow took the second place. In this study, a numerical model coupling lake current, wave and SSC of Lake Taihu was developed. In the SS model, the combined effects of wave and current were *** amounts of suspended and deposited sediments near the lake bed surface layer were treated separately. The stochastic characteristics of turbulent flow pulsation near lake beds were also considered, and the start-up conditions of sediment suspension were introduced to the model. The model elucidated the mutual exchange processes between sediment particles in SS and active sediments within and on the bed surface layer. Simulated results showed that lake current had relatively significant effects on the SSC at littoral areas of Lake Taihu, while SSC at the central area of the lake was mainly influenced by wave. The changes of transparency with SSC were simulated for Lake Taihu using this model. Calculated results were validated by measured data with good fitness, which indicated that the model is basically suitable for the simulation and prediction of transparency of Lake Taihu.

关键词： transparency suspended solid hydrodynamlc sediment suspension model.

Further study of sources of the imported cobalt-blue pigment used on Jingdezhen porcelain from late 13 to early 15 centuries

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science china(Technological sciences) 2008年第3期51卷 249-259页

作者： DU Feng1 & SU Baoru2 1 institute of Chemistry & Molecular Engineering, Qingdao university of science & technology, Qingdao 266000, china 2 College of Information science technology, Qingdao university of science & technology, Qingdao 266000, china institute of Chemistry & Molecular Engineering Qingdao University of Science & Technology College of Information science technology

Based on the conclusion of modern scientific analysis: the cobalt-blue pigment applied on Jingdezhen official porcelain during Yuan Dynasty and prior to Xuande reign of Ming Dynasty (1271―1425) contains high iron and low manganese con- tents, and the cobalt during Xuande and after Xuande periods (after 1426) of Ming Dynasty contains high manganese and low iron contents, in combination with the traditional archaeological method, the related historical textual records were in- vestigated and analyzed, the imported cobalt employed on Jingdezhen official porcelain was studied comprehensively, systematically and logically. In fact, 'Su Ma Li Qing' (Samarra-blue) and 'Su Bo Ni Qing' (Sumatra-blue) are definitely different cobalt ores originated in different places, because of their very similar translitera- tions in Chinese, the confusion has appeared in ancient books for more than 400 years, which considered 'Su Ma Li Qing' and 'Su Bo Ni Qing' as the same co- balt-blue pigment. In this article the mistake was corrected, the possible producing places and the approximate eras of the two pigments imported to china and used at Jingdezhen were also suggested.

关键词： imported cobalt-blue pigments employed on official blue-and-white porcelain Yuan Dynasty early Ming Dy- nasty Mn/Fe content ratio Su Ma Li Qing (Samarra-blue) Su Bo Ni Qing (Sumatra-blue) scientific archae- ological research transliteration

Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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science china Earth sciences 2008年第5期51卷 654-664页

作者： HU Guang1,2, JIN ZhangDong1 & ZHANG Fei3 1 State Key Laboratory of Loess and Quaternary Geology, institute of Earth Environment, Chinese Academy of sciences, Xi’an 710075, china 2 Graduate university of the Chinese Academy of sciences, Beijing 100049, china 3 College of resources and Environmental science, nanjing Agricultural university, nanjing 210095, china State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate university of the Chinese Academy of sciences Beijing China College of resources and Environmental science Nanjing Agricultural University Nanjing China

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

On the Isometric Minimal Immersion into a Euclidean Space

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Acta Mathematica Sinica,English Series 1999年第4期15卷 555-560页

作者： Qing Chen Department of Mathematics,The university of science and technology of china,Hefei 230026,p.r.china E-mail:qchen@*** Department of Mathematics The University of Science and Technology of China Hefei P. R. China

We study the volume growth of the geodesic balls of a minimal submanifold in a Euclidean space.A necessary condition for the isometric minimal immersion into a Euclidean space is obtained. A classification of non-posi... 详细信息

关键词： Minimal immersion Geodesic ball Volume growth ruled submanifolds

Spatial and Temporal Variability of N, p and K Balances for Agroecosystems in china

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pedosphere 2005年第3期15卷 347-355页

作者： SHENrun-ping SUNBo ZHAOQi-Guo instituteofSoilscience ChineseAcademyofSciencesNanjing210008（China）／／DepartmentofSpatialInformationScienceNanjingUniversityofInformationScienceandTechnologyNanjing210044（China） instituteofSoilscience ChineseAcademyofSciencesNanjing210008（China）

Nitrogen, phosphorus, and potassium balances for agroecosystems in china from 1993 to 2001 were calculated at national and provincial levels using statistical data and related parameters, and their spatial and temporal variabilities were analyzed with GIS to estimate the potential impacts of nutrient N, p and K surpluses or deficits to soil, water and air. At the national scale, the N and p balances from 1993 to 2001 showed a surplus, with the nitrogen surplus remaining relatively stable from 1997—2001. Although during this period the p surplus pattern was similar to N, it had smaller values and kept increasing as the use of phosphate fertilizer increased year by year. However, K was deficient from 1993 to 2001 even though from 1999 to 2001 the K deficit decreased. The spatial analysis revealed higher N surpluses in the more developed southeastern provinces and lowest in the western and northern provinces where there was less chemical fertilizer input. The serious K deficit mainly occurred in Shanghai and Beijing municipalities, Jiangsu, Zhejiang and Hubei provinces, and Xinjiang autonomous regions. For the years 1992, 1996 and 2001, N surpluses and K deficits had significant positive spatial correlations with per capita gross domestic product (GDp), per capita gross industrial output value, and per capita net income of rural households. This showed that the level of economic development played an important role on nutrient balances in the agroecosystems.

关键词： china economic factors NpK balance spatial and temporal variability

paddy Soil Stability and Mechanical properties as Affected by Long-Term Application of Chemical Fertilizer and Animal Manure in Subtropical china

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pedosphere 2007年第5期17卷 568-579页

作者： LI Jiang-Tao ZHANG Bin School of Geographic and Oceanographic sciences Nanjing University Nanjing 210093 （China） institute of Soil science Chinese Academy of Sciences Nanjing 210008 （China）

Wet stability, penetration resistance （pr）, and tensile strength （TS） of paddy soils under a fertilization experiment for 22 years were determined to elucidate the function of soil organic matter in paddy soil stabilization. The treatments included no fertilization （CK）, normal chemical fertilization （NpK）, double the NpK application rates （2NpK）, and NpK mixed with organic manure （NpK＋OM）. Compared with CK, Fertilization increased soil organic carbon （SOC） and soil porosity. The results of soil aggregate fragmentation degree （SAFD） showed that fast wetting by water was the key fragmentation mechanism. Among the treatments, the NpK＋OM treatment had the largest size of water-stable aggregates and greatest normal mean weight diameter （NMWD）（p ≤ 0.05）, but the lowest pr and TS in both cultivated horizon （Ap） and plow pan. The CK and 2NpK treatments were measured with pr 〉 2.0 Mpa and friability index 〈 0.20, respectively, in the Ap horizon, suggesting that the soils was mechanically unfavourable to root growth and tillage. In the plow pan, the fertilization treatments had greater TS and pr than in CK. TS and pr of the tested soil aggregates were negatively correlated to SOC content and soil porosity. This study suggested that chemical fertilization could cause deterioration of mechanical properties while application of organic manure could improve soil stability and mechanical properties.

关键词： soil aggregate stability chemical fertilization organic matter penetration resistance tensile strength

Microstructure and properties of Mg-12Gd-3Y-0.5Zr Alloys processed by ECAp and Extrusion

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Journal of Wuhan university of technology(Materials science) 2011年第6期26卷 1128-1132页

作者：朱荣 Department of Materials science and Engineering Nanjing University of Science and Technology

Equal channel angular pressing （ECAp） processing and conventional extrusion （Ex） were applied to the Mg-12Gd-3Y-0.5Zr （wt%） magnesium alloy in order to evaluate the potential improvement in the mechanical properties. The ECAp experiment was conducted at 380 ℃ in a die having an included angle of 90° between two channels by the Bc route with the billet rotated by 90° about its longitudinal axis. Subsequently, some billets were processed by conventional extrusion at 300 ℃. The microstructures were examined by X-ray diffraction （XrD）, optical microscopy and transmission electron microscopy （TEM）. The experimental results indicate that the grain size is refined effectively, but the basal planes are highly inclined （about 40o） from the extrusion axis introduced by ECAp, which impairs the grain boundary strengthening effect. The conventional extrusion, following the ECAp, can modify the grains in hard orientation. Based on grain boundary strengthening due to ECAp and texture strengthening due to Ex, the strength is improved effectively. The enhanced activity of the non-basal slips, due to the refined grains and the reduction in c/a ratio, is responsible for good ductility and high strain hardening rate in samples obtained by the two-step process.

关键词： magnesium alloy equal channel angular pressing thermomechanical processing texture

The DpGA for Conbining the Superscalar and Multithreaded processors principal

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High technology Letters 2001年第1期7卷 79-85页

作者： Abdelkadel Chaib, Hu Mingzeng (Department of Computer science and technology, Harbin institute of technology, Harbin 150001 p.r.china) Dept. of Computer Sci. and Technol. Harbin Institute of Technology Harbin 150001 China

The performance of scalable shared-memory multiprocessors suffers from three types of latency; memory latency, the latency caused by inter-process synchronization ,and the latency caused by instructions that take multiple cycles to produce results To tolerate these three types of latencies, The following techniques was proposed to couple: coarse-grained multithreading, the superscalar processor and a reconfigurable device, namely the overlapping long latency operations of one thread of computation with the execution of other threads The superscalar processor principle is used to tolerate instruction latency by issuing several instructions simultaneously The DpGA is coupled with this processor in order to improve the context-switching

关键词： DpGA Context switching Functional and control conflicts Data dependencies WAW rAW WAr hazards Tomasolo’s algorithm

Dynamic Mechanical Behaviour of Ultra-high performance Fiber reinforced Concretes

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Journal of Wuhan university of technology(Materials science) 2008年第6期23卷 938-945页

作者：赖建中 Department of Materials science & Engineering Nanjing University of Science & Technology

Ultra-high performance fiber reinforced concretes （UHpFrC） were prepared by replacing 60% of cement with ultra-fine industrial waste powder. The dynamic mechanical behaviour of UHpFrC with different fiber volume fraction was researched on repeated compressive impact in four kinds of impact modes through split Hopkinson pressure bar （SHpB）. The experimental results show that the peak stress and elastic modulus decrease and the strain rate and peak strain increase gradually with the increasing of impact times. The initial material damage increases and the peak stress of the specimen decreases from the second impact with the increasing of the initial incident wave. Standard strength on repeated impact is defined to compare the ability of resistance against repeated impact among different materials. The rate of reduction of standard strength is decreased by fiber reinforcement under repeated impact. The material damage is reduced and the ability of repeated impact resistance of UHpFrC is improved with the increasing of fiber volume fraction.

关键词： ultra-high performance fiber reinforced concretes split Hopkinson pressurebar dynamic repeated impact