TEMPORAL AND GEOMORPHIC VARIATIONS OF STREAM STABILITY AND MORPHOLOGY: MAHOGANY CREEK,NEVADA1

ABSTRACT: Detailed studies of long-term management impacts on rangeland streams are few because of the cost of obtaining detailed data replicated in time. This study uses government agency aquatic habitat, stream morphologic, and ocular stability data to assess land management impacts over four years on three stream reaches of an important rangeland watershed in northwestern Nevada. Aquatic habitat improved as riparian vegetation reestablished itself with decreased and better controlled livestock grazing. However, sediment from livestock disturbances and road crossings and very low stream flows limited the rate of change. Stream type limited the change of pool variables and width/depth ratio, which are linked to gradient and entrenchment. Coarse woody debris removal due to previous management limited pool recovery. Various critical-element ocular stability estimates represented changes with time and differences among reaches very well. Ocular stability variables tracked the quantitative habitat and morphologic variables well enough to recommend that ocular surveys be used to monitor changes with time between more intensive aquatic surveys.     

INTEGRATED RIVER BASIN OPTIMIZATION: MODELING ECONOMIC AND HYDROLOGIC INTERDEPENDENCE1

ABSTRACT: This paper presents an integrated optimal control model that optimizes economic performance of reservoir management in watersheds in which there are significant economic and hydrologic interdependencies. The model is solved using the General Algebraic Modeling System (GAMS). Results show that application of this model to New Mexico's Rio Chama basin can increase total system benefits over historical benefits by exploiting complementarities between hydroelectricity production, instream recreation, and downstream lake recreation.     

旱涝灾害的一些基本问题初探

首先就旱涝灾害对人类的作用进行了分析，认为它影响范围最大，危害程度最深．其次．对旱涝灾害的成因、确定旱涝灾害的定量指标以及评估旱涝灾害的指标体系进行分析探讨；最后对国内防御旱涝灾害的能力做了总体评价，并对其所采取的预防，救抗灾措施等进行分析．     

淮河上游洪水灾害可公度信息系预测

可公度信息系是一种源于天文学的预测方法，其实质是寻求事物发生的经验关系。本文应用此法对淮河上游的洪水灾害进行了预测分析，结果表明淮河上游洪水灾害发生具有２ａ、４ａ、５ａ、７ａ、９ａ、１１ａ、１９ａ及７１ａ等多种周期，并在１９９７年、２０００年等年份的前后有可能发生大洪水。     

自然灾害不同灾情的比较方法探讨

用计算自然灾害不同灾情的灰色关联度的方法，来对不同灾情进行比较分析。该方法不仅能够比较同一灾级中不同的灾情，也能够对不同灾级的灾情差异程度作比较分析，因而它与现有的不同灾情的比较方法相比，更科学合理。     

太阳能光催化降解法去除水中罗丹明染料的研究

在太阳光的紫外线辐射下，应用载有ＴｉＯ２薄层的平板式光催化反应器，进行了光催化降解法去除水中罗丹明染料的试验，结果表明，当紫外线辐射强度平均为３３Ｗ／ｍ＾２，反应时间为１８ｍｉｎ时，水中罗丹明染料浓度由１０ｍｇ／Ｌ降至０．０１ｍｇ／Ｌ，在室国家排放标准，探讨了太阳能光催化反应系统的改进方向及工业化应用的有关问题。     

Thermal and mechanical properties of poly(lactic Acid) and poly(ethylene/butylene Succinate) blends

In this study, blends of poly (lactic acid) (PLA) with poly(ethylene/butylene succinate) (Bionolle) have been investigated for their thermal and mechanical properties as a function of the concentration of Bionolle. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile tests were used to characterize the blends. From the results of the DMA and DSC, it was found that this blend system was not miscible within the compositions studied. DSC results showed that adding Bionolle aids in crystallization of PLA. It was observed that increasing the Bionolle concentration led to a slight increase in the strain-at-break of the blends but a decrease in the Young’s modulus and ultimate tensile strength. Biaxially oriented films showed an increase in tensile strength, modulus, and strain-at-break.     

Pressure- volume- temperature relationships of soy protein isolate/starch plastic

The use of pressure-volume-temperature (PVT) studies in processing of a biodegradable plastic composition made from soy protein isolate and corn starch is described. The ability of PVT measurements to predict the combined effects of pressure, volume, and temperature effects is demonstrated. The results show that the PVT relations of the plastic can be predicted by using a regression analysis similar to the Tait equations of state. A change in slope of the PVT curves was observed at around 80‡C, which is ascribed to the glass-transition process of the plastic. Evidence of onset of thermal degradation of the plastic was observed at ca. 160‡C under 0 to 200 MPa isobaric pressure. This thermal degradation precluded determination of the crystal melting point of the plastic.     

中国可持续发展与国家安全文化战略的新对策

“可持续发展”战略的实质是社会、经济发展与资源、环境相协调的一种发展模式。值得注意，这一人类社会发展模式中跨世纪重大转变的策略，尚未引起安全与减灾科技界的普遍关注，不仅在安全减灾战略研究中很少涉及，严重的是它阻碍了安全减灾诸领域跨世纪及决策课题研究的深度，造成与国际接轨进程缓慢。为此，立足可持续发展思路，并以全新视角、系统地讨论适宜安全减灾文化战略的总体对策，可望能为中国二十一世纪安全保障及科技发展提供科学指南