CLIGEN非降水要素在黄土塬区的适用性评估

许多基于物理机制的水文和作物模型需要日序列气象数据来驱动,CLIGEN是为WEPP等模型产生气候输入文件的天气发生器,可以产生10个日序列气象变量来满足这种需要,但是其在中国的适用性需要进行评估。研究的目标是利用黄土高原陕西长武1957~2001年的气象数据评估CLIGEN产生非降水要素(最高温度、最低温度、露点温度、太阳辐射和风速)的能力。结果表明,CLIGEN对最高温度、最低温度和露点温度的模拟效果较好,对太阳辐射和极端气候事件的模拟效果较差,对风速的模拟效果最差。相关性检验表明CLIGEN很好地保持了气象要素的季节性,这对模拟农业生产是非常重要的;但是没有保留气象要素逐日的自相关和互相关性,进而导致产生的温度变化不符合连续渐变的规律。

A Viscoelastic Constitutive Model with Nonlinear Evolutionary Internal Variables

Based on the internal variable theory, a viscoelastic constitutive model of a highly deformable continuous medium is proposed. A set of second rank tensorial internal state variables corresponding to Biot's strain is introduced, and a nonlinear evolution

A Multimoment Finite-Volume Shallow-Water Model On The Yin-Yang Overset Spherical Grid

A numerical model for shallow-water equations has been built and tested on the Yin-Yang overset spherical grid. A high-order multimoment finite-volume method is used for the spatial discretization in which two kinds of so-called moments of the physical field [i.e., the volume integrated average ( VIA) and the point value (PV)] are treated as the model variables and updated separately in time. In the present model, the PV is computed by the semi-implicit semi-Lagrangian formulation, whereas the VIA is predicted in time via a flux-based finite-volume method and is numerically conserved on each component grid. The concept of including an extra moment (i.e., the volume-integrated value) to enforce the numerical conservativeness provides a general methodology and applies to the existing semi-implicit semi-Lagrangian formulations. Based on both VIA and PV, the high-order interpolation reconstruction can only be done over a single grid cell, which then minimizes the overlapping zone between the Yin and Yang components and effectively reduces the numerical errors introduced in the interpolation required to communicate the data between the two components. The present model completely gets around the singularity and grid convergence in the polar regions of the conventional longitude-latitude grid. Being an issue demanding further investigation, the high-order interpolation across the overlapping region of the Yin-Yang grid in the current model does not rigorously guarantee the numerical conservativeness. Nevertheless, these numerical tests show that the global conservation error in the present model is negligibly small. The model has competitive accuracy and efficiency.

Geographic variation of Chevrier's field mouse (Apodemus chevrieri) (Milne-Edwards, 1868) (Muridae : Murinae) from southwestern China based on cranial morphometric variables

Geographic variation of Chevrier's field mouse (Apodemus chevrieri) (Milne-Edwards, 1868) (Muridae: Murinae) from southwestern China based on cranial morphometric variables. Zoological Studies 47(4): 393-401. A sample of 134 specimens of Apodemus chevrieri was investigated in the present study. Individuals were divided into male and female groups, and these were respectively subjected to multivariate analysis. Results indicated that 3 geographic populations of A. chevrieri inhabit southwestern China: a Sichuan population in western Sichuan Province; a northwestern Yunnan population ranging from northwestern Yunnan Province eastward to southern Sichuan Province; and a central Yunnan population in central Yunnan Province. In addition, a coefficient of difference analysis was performed among these 3 geographic populations. The results suggested that these 3 geographical populations of A. chevrieri belonged to 2 subspecies. Furthermore, we discuss the relationships of the subspecific differentiation of A. chevneri with changes in latitude in southwestern China.

Geographic variation of the Perny's Long-nosed squirrels (Dremomys pernyi) (Milne-Edwards, 1867) (Rodentia : Sciuridae) from southwestern China based on cranial morphometric variables

A sample of 114 specimens of Dremomys pernyi was investigated, 73 of which had intact skulls and were subjected to multivariate, coefficient of difference (C. D.), and cluster analyses. Results indicate that 4 subspecies (groups) of Dremomys pernyi inhabi

Geographic variation of the Anderson's Niviventer (Niviventer andersoni) (Thomas, 1911) (Rodentia: Muridae) of two new subspecies in China verified with cranial morphometric variables and pelage characteristics

A total of 66 specimens of Niviventer andersoni with intact skulls was investigated on pelage characteristics and cranial morphometric variables. The data were subjected to principal component analyses as well as to discriminant analyses, and measurement

Variables affecting melanoidins removal from molasses wastewater by coagulation/flocculation

Coagulation/flocculation process was applied in the polishing treatment of molasses wastewater on a bench-scale. Important operating variables, including coagulant type and dosage, solution pH, rapid mixing conditions as well as the type and dosage of polyeletrolytes were investigated based on the maximum removal efficiencies of chemical oxygen demand (COD) and color, residual turbidity and settling characteristics of flocs. HPSEC was utilized to evaluate the removal of molecular weight fractions of melanoidins-dominated organic compounds. Experimental results indicate that ferric chloride was the most effective among the conventional coagulants, achieving 89% COD and 98% color eliminations; while aluminum sulfate was the least effective, giving COD and color reductions of 66% and 86%, respectively. In addition to metal cations, counter-ions exert significant influence on the coagulation performance since Cl--based metal salts attained better removal efficiency than SO42--based ones at the optimal coagulant dosages. Coagulation of molasses effluent is a highly pH-dependent process, with better removal efficiency achieved at lower pH levels. Rapid mixing intensity, rather than rapid mixing time, has relatively strong influence on the settling characteristics of flocs formed. Lowering mixing intensity resulted in increasing settling rate but the accumulation of floating flocs. When used as coagulant aids, synthetic polyelectrolytes showed little effects on the improvement in organic removal. On the other hand, cationic polyacrylamide was observed to substantially enhance the settleability of flocs as compared to anionic polyacrylamide. The effects of rapid mixing conditions and polymer flocculants on the coagulation performance were discussed. (C) 2009 Elsevier B.V. All rights reserved.

Influence of environmental variables on macroinvertebrates in a macrophyte-dominated Chinese lake, with emphasis on the relationships between macrophyte heterogeneity and macroinvertebrate patterns

The benthic community structure in Baoan Lake was examined in relation to lake water physicochemical characteristics and biological parameters. Seventy macroinvertebrate taxa were identified, and mollusks constituted the dominant group and accounted for more than 80% of the total abundance. Assemblages were composed mainly of scrapers (81.5%) and collector-gatherers (roughly 10%). Three plant variables (richness, total cover, and total biomass) were strongly correlated with the faunal gradient (p<0.05). Other predicator variables were Cl-, SiO2, and chemical oxygen demand. Because of the importance of macrophytes in structuring benthic assemblage in this lentic system, the spatial heterogeneity of macrophytes also influenced the pattern of macroinvertebrates. Seven lake regions were uniquely characterized according to primary macrophyte composition and biomass. There were significant differences for macroinvertebrate taxa richness, abundance, and biodiversity among the seven macrophyte regions.

Differing estrogen activities in the organic phase of air particulate matter collected during sunny and foggy weather in a Chinese city detected by a recombinant yeast bioassay

Total air suspended particles (PM 100) collected from an urban location near a traffic line in Wuhan, China, were examined for estrogen using a recombinant yeast bioassay. Wuhan, located at the central part of China, is the fourth biggest city in China with 7 million populations. Today, Wuhan has developed into the biggest city and the largest traveling center of central China, becoming one of the important bases of industry, education and research. Wuhan is right at the confluent point of Yangzi River, the third longest river in the world, and its largest distributary Hanjiang, with mountains and more than 100 takes in downtown area. Therefore, by its unique landscape, Wuhan has formed clear four seasons with relatively long winter and summer and short spring and autumn. Foggy weather usually happen in early spring. The yeast line used in this assay stably expresses human estrogen receptor-alpha. Weak but clear estrogenic activities were detected in the organic phase of crude extracts of air particle materials (APM) in both sunny and foggy weather by 0.19-0.79 mug E2/gPM(100) which were statistically significantly elevated relative to the blank control responding from 20% to 50% of the maximum E2 response, and the estrogenic activity was much higher in foggy weather than in sunny weather. The estrogenic activities in the sub-fractions from chromatographic separation of APM sampled in foggy days were also determined. The results indicated that the responses of the fractions were obviously higher than the crude extracts. Since there is no other large pollution source nearby, the estrogenic material was most likely from vehicle emissions, house heating sources and oil fumes of house cooking. The GC/MS analysis of the PM100 collected under foggy weather showed that there were many phenol derivatives, oxy-PAHs and resin acids which have been reported as environmental estrogens. These results of the analysis of estrogenic potency in sunny and foggy weather in a subtropical city of China indicate that further studies are required to investigate the actual risks for the associated health and atmospheric system. (C) 2004 Elsevier Ltd. All rights reserved.

Structure of macrozoobenthos of the East Dongting nature reserve, with emphasis on relationships with environmental variables

Ecological survey of macrozoobenthos assemblages was carried out at 32 sites in the East Dongting Nature Reserve, located in the northern region of the East Dongting Lake in the middle basin of the Yangtze River, China. All total 51 taxa including 18 oligochaetes, 15 mollusks, 14 insects and four other animals were recorded. Mollusks composed the dominant group and accounted for more than 70% of the total abundance. Assemblages were composed mainly of scrapers (66.7%) and collector-gatherers (nearly 20%), and to a lesser extent collector-filterers (roughly 12%), predators (ca. 7%), and shredders (ca. 6%). Two-way indicator species analysis, detrended correspondence, and canonical correspondence analysis (CCA) were employed to identify the relationships between macrozoobenthos assemblages and environmental variables. Thirty-two sites were separated into four site groups based on composition and relative abundance of benthic macroinvertebrates. CCA detected that water depth, pH, conductivity, SiO2, total nitrogen, total phosphorus, alkalinity, hardness, and Ca2+, were significant environmental factors influencing the pattern of macozoobenthos. In this minimal subset, water depth, pH, alkalinity and hardness were the most influential variables.

A 16-term error model based on linear equations of voltage and current variables

Formulation of a 16-term error model, based on the four-port ABCD-matrix and voltage and current variables, is outlined. Matrices A, B, C, and D are each 2 x 2 submatrices of the complete 4 x 4 error matrix. The corresponding equations are linear in terms of the error parameters, which simplifies the calibration process. The parallelism with the network analyzer calibration procedures and the requirement of five two-port calibration measurements are stressed. Principles for robust choice of equations are presented. While the formulation is suitable for any network analyzer measurement, it is expected to be a useful alternative for the nonlinear y-parameter approach used in intrinsic semiconductor electrical and noise parameter measurements and parasitics' deembedding.