Incorporating Soil Associations into Linear Programming Models for Development of Irrigation Scenarios

An inadequate streamflow supply in Saginaw Bay, Michigan, affects the irrigation development in the region. Linear programming (LP) models are developed in this paper to help irrigation planners determine optimal irrigation scenarios. To incorporate the spatial variations of the soil and climate into the optimization models, soil associations are used as the basic analysis unit for estimating crop yields, irrigation requirements, and expected economic returns. The yields and irrigation requirements of corn, drybeans, and soybeans are simulated by the CERES-MAIZE, BEANGRO, and SOYGRO models at each of the twelve soil associations in the study area over the period of 1951–1980. The yield and irrigation requirement of sugarbeets are simulated by the YIELD model for all the soils in the study area over the period of 1956–1987. The crop prices, simulated crop yields and irrigation requirements, and variable costs are used to compute the expected gross margins and other coefficients in the LP models. The optimization results provide irrigation scenarios that are linked to specific soil associations, which are more useful to decision makers for identifying and targeting individual soils for irrigation development than are the spatially lumped optimal solutions. This study demonstrates that through integration of GIS and simulation models, spatial variations of the climate, soil, and water resources can be better represented in the optimization models to produce more realistic irrigation scenarios.     

文物工作基础识讲座 第五讲 文物的有效保护(上)

依靠法律手段来实施对文物的有效保护 ,是当今世界上各个国家的普遍做法。本文就我国的文物保护问题 ,从法律体系、受保护的范围、行使主体、公民保护文物的权利和义务四个方面进行了阐述     

20世纪伊朗与以色列关系评析

本文认为,巴列维时期伊朗与以色列结成“外围联盟”,共同应对苏联的威胁和激进阿拉伯国家的挑战。伊朗伊斯兰教革命后,尽管霍梅尼从意识形态出发强烈反对以色列,但因各自国家安全利益的需要,两伊战争期间伊以仍然保持着秘密武器交易。随着冷战后苏联的解体和伊拉克在海湾战争中被削弱,共同的敌人消失了,伊以为争夺在中东地缘政治中的优势地位展开了激烈竞争甚至对抗,伊朗以反对中东和平进程和支持阿拉伯激进组织来对付以色列;而以色列则竭力把伊朗排除在中东和平进程之外,大力渲染伊朗伊斯兰原教旨主义和伊核计划对中东稳定及世界和平的威胁,以引起美国等西方国家对伊朗的关注、制裁,甚至军事打击,保持以色列在中东的强国地位。     

实事求是是唯物史观的基本原则——以“五种社会形态理论”为中心的探讨

是否遵循实事求是的方法论原则,是判定唯物史观还是唯心史观的根本标志,也是二者判然有别的分水岭。唯物史观不以任何先验的东西为前提,唯心史观则相反。凡是不遵循实事求是方法论原则乃至有意违反这一原则的历史观,毫无疑问一定是唯心史观,而绝非唯物史观。根据实事求是原则去考察历史,符合过去人们所理解的五种社会形态理论本来所规定的意义和内涵,因生产力不断发展而导致五种社会形态依次演进更替的例子,在人类历史上并不存在。     

初版与再版邮票的质子激发X荧光鉴别法

报道用质子激发X荧光（PIXE）法分析我国初版与再版纪念邮票和特种邮票的实验结果。实验表明,初版和再版邮票所用印刷油墨颜料的化学元素的成分是不同的,因而PIXE方法可以用来实现初版和再版珍贵邮票的无损鉴定。这一方法也可以应用到对某些重要纸质文献或艺术品真伪的鉴定。     

铜绿山古铜矿遗址古坑木防腐保护

通过模拟试验和现场试验,对铜绿山古铜矿遗址古坑木的保护方法进行了研究,找到了一种较适合于古铜矿遗址使用的古坑木保护方法,取得了较好的效果。     

山东青铜镜金相分析──兼论我国古镜的组织特征

对12件山东古代青铜镜进行了金相分析,其中6件为铸态,6件为热处理态,热处理的基本特征是：观察面上可看到许多明晃的交叉状物和不太明显的晶界状、环链状物。这与我国古镜的特征组织是一种“两端尖锐的长条状及针状”物之说是不相符的。     

清代皇家赐园与北大校园

今天北京大学校园里的旧日园林,是清代皇家园林系统中的重要组成部分。本文根据大量的档案史料,对校园内清代的鸣鹤园、镜春园、朗润园、淑春园、十笏园、弘雅园、佟氏园、苏大人园、蔚秀园、承泽园十园进行了全面的梳理和考订。     

Quantitative estimation of overpressure caused by gas generation and application to the Baiyun Depression in the Pearl River Mouth Basin,South China Sea

Hydrocarbon generation can yield high fluid pressures in sedimentary basins as the conversion of solid kerogen to hydrocarbons can result in an increase in fluid volume. To quantify the relationship between gas generation and overpressure in source rocks, a set of equations for computing the pressure change due to gas generation has been derived. Those equations can be used to quantitatively estimate overpressure generated by type III kerogen in source rocks by considering gas generation and leakage, gas dissolution in formation water and residual oil, thermal cracking of oil to gas, and hydrocarbon episodic expulsion from source rocks. The equations also take consideration of other factors including source rock porosity, transformation ratio, total organic carbon (TOC), hydrogen index, and compressibility of kerogen, oil, and water. As both oil and gas are taken into account in the equations, they can also be used to estimate the evolution of overpressure caused by hydrocarbon generation of type I and type II kerogen source rocks. Sensitivity analyses on the type III kerogen source rock indicate that hydrogen index is the most influential parameter for overpressure generation, while TOC and residual gas coefficient (β: ratio of residual gas over the total gas generated) have a moderate effect. Overpressure can be generated even if the gas leakage/loss in the source rock is up to 80% of the total gas generated. This suggests that the internal pressure seal of the source rock is not a critical factor on the pressure change as long as the source rocks are capable of sealing liquid oil. The equations were applied to evaluate the overpressure in the Eocene–Oligocene Enping Formation source rocks due to hydrocarbon generation in the Baiyun Depression, the Pearl River Mouth Basin by considering the source rock properties, hydrocarbon generation history, and hydrocarbon expulsion timing. Two episodes of overpressure development due to gas generation and release were modeled to have occurred in the Enping Formation source rock since 16 Ma. The overpressure release at 10.2–5.3 Ma via hydrocarbon expulsion was apparently related to the Dongsha phase of tectonic deformation, whereas the pressure release at 2–0 Ma was due to pressure generation that was exceeded the fracture‐sealing pressure in the source rocks.     

A comprehensive review of hydrocarbons and genetic model of the sandstone‐hosted Dongsheng uranium deposit,Ordos Basin,China

The Dongsheng uranium deposit, the largest in situ leach uranium mine in the Ordos Basin, geometrically forms a roll‐front type deposit that is hosted in the Middle Jurassic Zhiluo Formation. The genesis of the mineralization, however, has long been a topic of great debate. Regional faults, epigenetic alterations in surface outcrops, natural oil seeps, and experimental findings support a reducing microenvironment during ore genesis. The bulk of the mineralization is coffinite. Based on thin‐section petrography, some of the coffinite is intimately intergrown with authigenic pyrite (ore‐stage pyrite) and is commonly juxtaposed with some late diagenetic sparry calcite (ore‐stage calcite) in primary pores, suggesting simultaneous precipitation. Measured homogenization temperatures of greater than 100°C from fluid inclusions indicate circulation of low‐temperature hydrothermal fluids in the ore zone. The carbon isotopic compositions of late calcite cement (δ¹³C_VPDB = ?31.0 to ?1.4‰) suggest that they were partly derived from sedimentary organic carbon, possibly from deep‐seated petroleum fluids emanating from nearby faults. Hydrogen and oxygen isotope data from kaolinite cement (δD = ?133 to ?116‰ and δ¹⁸O_SMOW = 12.6–13.8‰) indicate that the mineralizing fluids differed from magmatic and metamorphic fluids and were more depleted in D (²H) than modern regional meteoric waters. Such a strongly negative hydrogen isotopic signature suggests that there has been selective modification of δD by CH₄±H₂S±H₂ fluids. Ore‐stage pyrite lies within a very wide range of δ³⁴S (?39.2 to 26.9‰), suggesting that the pyrite has a complex origin and that bacterially mediated sulfate reduction cannot be precluded. Hydrocarbon migration and its role in uranium reduction and precipitation have here been unequivocally defined. Thus, a unifying model for uranium mineralization can be established: Early coupled bacterial uranium mineralization and hydrocarbon oxidation were followed by later recrystallization of ore phases in association with low‐temperature hydrothermal solutions under hydrocarbon‐induced reducing conditions.