二龙山水库流域生态环境与小气候的关系研究

根据不同的植被覆盖率,对二龙山水库流域进行分区,并在春季组织小气候观测,研究不同小区的小气候综合特征.分析结果表明,二龙山水库流域生态环境与小气候综合特征之间存在密切关系.      

Estimating Forest Ecosystem Evapotranspiration at Multiple Temporal Scales With a Dimension Analysis Approach1

Abstract:  It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales.     

Development of inherent safety and health index for formulated product design

The numerous formulated products which are introduced to the market consist of chemical ingredients that may cause various safety and health hazards to the consumers. Therefore, it is extremely important to practice a systematic methodology to formulate products with acceptable safety and health performances. This work presents an index-based methodology to assess the safety and health hazards of the ingredients during the early formulation stage of product design. Hence, new inherent safety and health sub-indexes are introduced to improve the current safety and health hazards that are needed in formulated product design. The inherent safety and health sub-indexes are assigned with scores based on the degree of potential hazards. A higher score indicates a higher safety risk or severe health effect, and vice versa. The proposed methodology will greatly assist the users to identify the adverse safety and health effects caused by the ingredients. Hence, it is pivotal to eliminate or reduce the safety and health impacts from product usage. A case study on common ingredients used in the formulation of paint is presented on this study to describe the proposed method.     

关于耕地总量动态平衡的思考

中国是一个人多地少的国家，伴随着80年代经济高速增长而加剧的人地矛盾已经成为区域可持续发展面临的一个重要问题。本文以大量的数据分析了自耕地总量动态平衡实施以来的1999-2001年耕地数量和质量的变化，其中用播面单产和复种指数来度量耕地质量，得出了我国总体耕地质量下降的结论，指出仅仅从数量上实施耕地总量动态平衡，保证不了我国粮食安全的需要。并在此基础上提出了相关的建议。     

三层复合铝合金板材的复合工艺和结合机制

研究了Al-Si/Al-Mn/Al-Si三层复合板热轧复合工艺,借助金相显微镜、扫描电镜、能谱仪分析了复合工艺参数对轧后结合强度和剥离面形貌的影响,得到了优化热轧复合工艺,并对热轧复合板界面结合机制进行了探讨.     

A SENSITIVITY ANALYSIS OF THE PALMER HYDROLOGIC DROUGHT INDEX1

ABSTRACT: The sensitivity of the Palmer Hydrologic Drought Index to departures from average temperature and precipitation conditions is examined. A time series of zero index values was calculated and then one monthly temperature or precipitation value was perturbed. The resulting time series shows the effects on the index of one anomalous value. Independent series were calculated for temperature anomalies of plus and minus 1, 3, 5, and 10F and for precipitation anomalies of 25, 50, 75, 125, 150, and 200 percent of normal for each calendar month for Colorado, Indiana, Nevada, New York, Oklahoma, South Carolina, South Dakota, Washington, and Wisconsin. Analysis of the time series showed that the period of time required for the index to reflect actual rather than artificial initial conditions could be more than four years. It was also found that the effects of temperature anomalies are insignificant compared to the effects of precipitation anomalies. In some cases, one anomalous precipitation value could result in established wet or dry spells that last for up to two years. Although not examined in detail, the time series suggest that distributions of index values may be asymmetrical and possibly bimodal.     

差厚贴合减振钢板成形性的数值模拟研究

采用有限元软件MSC.Marc基于更新拉格朗日的弹塑性本构方程,对减振钢板的拉深变形进行了数值模拟。模拟得出了变形过程中的应力应变状态和错动量分布。通过改变内外两层钢板的厚度比,分析了差厚贴合对减振钢板拉深变形错动量的影响。为减振钢板的设计和应用研究提供了可靠的理论依据。     

Effects of soil properties, mulch and NPK fertilizer on maize yields and nutrient budgets on ferralitic soils in southern Benin

Four on-farm experiments examined whether modest applications of fertilizers in combination with prunings from native agroforestry trees would be an alternative to maintain the fertility of ferralitic soils in Benin. An application of about 1.9 t ha⁻¹ dry matter of mulch of Senna siamea combined with 30 kg N ha⁻¹, 22 kg P ha⁻¹ and 25 kg K ha⁻¹ as compound fertilizer was compared with (1) 60 kg N ha⁻¹, 43 kg P ha⁻¹ and 50 kg K ha⁻¹ as compound fertilizer alone, (2) mulch of S. siamea alone (about 3.2 t ha⁻¹ dry matter), and (3) a control treatment. Criteria were soil properties, yields, nutrient uptakes, and nutrient budgets. Application of sole mulch had no significant effects (P>0.05) on maize yields, while combined application of prunings and NPK fertilizers or sole NPK increased yields significantly (P<0.05). The most limiting nutrient was P. The local maize cultivar was efficient in P uptake, but not in internal nutrient utilization efficiency; mulch increased significantly the internal P utilization efficiency (P<0.05). Soil properties were interpreted with the QUEFTS (quantitative evaluation of the fertility of tropical soils) computer program. The predicted and measured yields were almost the same for maize without NPK. The measured responses to NPK were much lower than the responses calculated by QUEFTS. The calculated nutrient budgets were split into balances for available nutrients and for those not immediately available (NIA). Nutrient budgets were negative for the control and sole mulch treatments, and positive for the NPK treatments. Mulch improved the balances of NIA nutrients. The present experiment could not prove that combining NPK with mulch is the best option for sustainable agriculture. It may be more economical to apply lower rates of fertilizer to local maize than those applied in the two NPK treatments in the present study.     

地被物对土壤水分动态和水量平衡的影响研究

通过土壤水分渗漏装置试验研究了百喜草( Paspalum notatum) 及其枯落物在红壤坡地对土 壤水分动态和水量平衡的影响。结果表明, 百喜草覆盖(A) 、百喜草敷盖(B) 、裸露对照(C) 的地表径 流系数分别为1.35%、2.78%和32.74%, C 的地表径流量分别是A、B 的24.25 倍和11.78 倍。A、B、C 的月均土壤含水量变化规律显示, 地被物对土壤含水量的影响随季节的不同而不同, 不同地被物可 以增加或减少土壤水分。年均土壤含水量排列顺序是: B( 27.09%) >A( 26.46%) >C( 26.27%) 。不同处 理水量平衡各分量有较大差异。在2002 年降雨量1 808.5mm 的情况下, A、B、C 的年总径流深分别 为1 245.24、1 453.81 和1 383.23mm, 蒸散量分别为562.74、347.91 和413.82mm, 土壤蓄水年变化 量分别为0.52、6.78 和11.45mm。     

关于宽板塑性弯曲变薄理论解的讨论

指出了宽板塑性弯曲原理论解[1]和实验值[2]的矛盾,提出了一种新的理论解法,并与实验值作了比较,二者非常接近。