晶化时间对CoAPO-11分子筛合成过程中转晶的影响

本文研究了晶化时间对低钴含量(x=0.1)的CoAPO-11分子筛合成过程中转晶现象的影响,并采用XRD、SEM对产物进行表征。结果表明,200℃下晶化48 h,可获得纯相CoAPO-11;当晶化时间超过48 h时,产物便开始向[Co-Al-P-O]-GIS型分子筛转化;晶化延长至72 h时,产物已全部转化为[Co-Al-P-O]-GIS型分子筛,该转化过程不可逆。从分子筛骨架结构单元出发,阐述了转晶现象的内在影响因素。     

浅谈我国超细碳酸钙生产技术现状及发展方向

文章提出“碳化工艺连续化、活化剂复合化、活化技术组合化、活化温度常温化、干燥技术组合化和系统工程化”,应成为我国超细碳酸钙生产技术未来发展的主要方向,并论述了我国目前超细碳酸钙生产技术的现状,用连续鼓泡碳化工艺来改造现有碳化工艺,并提出了超重力反应结晶法的完善办法。     

基于遗传算法的核函数参数优化

核主分量分析是一种输入输出特征非线性变换技术。选择最优或接近最优的非线性变换核函数参数,使类的可分性测度最大,是KPCA应用于特征提取的关键。本文采用高斯变异遗传算法作优化技术,实现了KPCA和GA的集成,适合核函数参数的优化选择。仿真表明,该技术可行、有效。     

牦牛坪稀土矿区氟碳铈矿与氟碳钙铈矿矿物学

四川省牦牛坪稀土矿区钙稀土氟碳酸盐矿物有氟碳铀矿、氟碳钙铈矿以及笔者发现并命名的牦牛矿。本文旨在简述氟碳铈矿和氟碳钙铈矿的矿物学特征。牦牛坪钙稀土氟碳酸盐类矿物具有强选择轻稀土的特点。其中占９０％以上的氟碳铈矿有两种类型，一种为裂理发育的板状半自形柱状晶体，矿区大量出现。另一种为自形柱状晶体，在矿区极为少见，这种柱状自形氟碳柿矿晶体在自然界中极为罕见。红外吸收光谱表明，氟碳铈矿结构中，具有少量的附加阴离子（ＯＨ）－或者氟碳铈矿中有极少量羟氟碳铈矿。氟碳钙铈矿多为自形晶体，晶面横纹发育，形态多样、典型。但矿区含量甚微。Ｘ射线衍射分析表明，用Ｘ射线苷多菲照相不能分辨钙稀土氟碳酸盐系列矿物经常发育的体衍生多晶现象。     

Ex-post full surplus extraction,straightforwardly

Consider an estimate of the common value of an auctioned asset that is symmetric in the bidders’ types. Such an estimate can be represented solely in terms of the order statistics of those types. This representation forms the basis for a pricing rule yielding truthful bidding as an equilibrium, whether bidders’ types are affiliated or independent. We highlight the link between the estimator and full surplus extraction, providing a necessary and sufficient condition for ex-post full surplus extraction, including the possibility of independent types. The results offer sharp insights into the strengths and limits of simple auctions by identifying the source of informational rents in such environments. Harstad acknowledges hospitable accommodation by the Fuqua School of Business, Duke University, and the Olin School of Business, Washington University in St. Louis, during parts of this research. We are grateful for comments and suggestions from Richard McLean and Jeroen Swinkels.     

Uncertain Climate Change in an Intergenerational Planning Model

A three-generation planning model incorporating uncertain climate change is developed. Each generation features a production activity based on capital and an exhaustible resource. An irreversible climate change may occur in period two or three, reducing the productivity for this and the remaining generation. The model is solved by stochastic dynamic programming. If the climate impact and climate change probability is constant, the optimal period one (and two) resource extraction is larger than for the reference case of climate stability. If, however, climate impact and climate change probability increases with increased aggregate resource use, this result is reversed.     

高硫减压渣油加工方案的技术经济比较

对中国石化齐鲁分公司高硫减压渣油两种生产方案,即减压深拔工艺生产重交沥青和VRDS-FCC组合工艺生产轻质油品进行技术经济比较.结果表明:在公司裂解原料不能完全自给的前提下,VRDS-FCC组合工艺的单位利润优于减压深拔工艺,但随着重交沥青价格的上升,VRDS-FCC组合工艺的优势将逐渐减弱.     

因子分析中公因子提取方法的比较与选择

近代和现代统计分析方法中，因子分析是最重要的方法之一。因子分析中有7种提取公因子的方法，其中主成分法、极大似然法和主轴因子法是常用的方法。在着重解析这三种方法基本数学过程的基础上，对其适用条件和应用注意事项进行了比较，最后结合实例比较了不同公因子提取方法的结果，并对提取公因子过程中出现的问题给出了可能的解决办法。     

40CrNi_2Si_2MoVA钢棒材晶粒度控制

随着科技的进步与发展,以改变合金成分提高超高强度钢的强度和韧性已经很困难。本文以40Cr Ni2Si2Mo VA钢为例,探讨了通过控制晶粒度尺寸提高钢强度和韧性的方法。     

The cost of unconventional gas extraction: A hedonic analysis

We focus on identification and estimation of potentially negative environmental impacts of unconventional natural gas extraction on property values in the United States and advance previous research by contributing new data and new identification strategies for isolating these potential impacts. Our study area consists of two counties in Pennsylvania that are home to large amounts of unconventional natural gas extraction but are otherwise isolated from other resource extraction industries or large urban areas. We deploy parametric, semi-parametric, and matching hedonic regression models that include recent quasi-experimental methods and, in contrast to previous research and much popular intuition, we fail to find robust significance that negative environmental externalities of natural gas extraction are manifested in nearby property values. While there may be plausible risks associated with unconventional natural gas extraction, we do not find consistent evidence to suggest that these risks significantly affect nearby property values.