浅谈建设工程造价控制

从项目决策阶段、设计阶段、招投标阶段、施工阶段,竣工结算阶段等几个方面对建设工程造价控制做了介绍。     

墨西哥湾北陆坡区冷泉碳酸盐岩脂肪酸及碳同位素特征

对墨西哥湾北部水深约540m的上陆坡GC185区(GC-F样品)和水深约2200m的下陆坡AC645区(AC-E样品)冷泉碳酸盐岩中的脂肪酸及其单体化合物的δ13C进行了分析.在AC-E和GC-F冷泉碳酸盐岩样品中检测到了30多种脂肪酸化合物,均以主峰碳为C16的低碳数(C20)脂肪酸为主,具偶碳优势,主要包括正构脂肪酸、异构(i-)/反异构(ai-)脂肪酸以及带支链的(iso/anteiso)奇碳数脂肪酸.其中n-C12:0,n-C13:0,i-C14:0和n-C14:0具有明显偏低的δ13C值(-39.99‰~-32.36‰),可能来源于冷泉生物.n-C18:2和C18:1△9具有相同的碳同位素值,可能来源于冷泉渗漏区贝氏硫细菌属/辫硫菌属.支链奇碳数脂肪酸(iso/anteiso-C13~C17)具有特别负的δ13C值(-63.95‰~-44.17‰),明显不同于其他类别脂肪酸的碳同位素值,推断这类化合物是海底渗漏区甲烷厌氧氧化过程中的硫酸盐还原细菌生命活动的产物.     

The minimal rank correlation,subject to order restrictions,with application to the weighted linear choice model

The weighted linear choice model is one of the most popular models in the social sciences. In this model the utility of a choice object is represented as a weighted sum of attribute-level desirabilities, where the weights are attribute importances. In many empirical contexts the choice objects are such that individuals are highly correlated in terms of their desirability ordering of levels within attribute (e.g., price levels, durability levels, etc.) but may differ appreciably in terms of their evaluations of each attribute's importance.In this paper we address the problem of how dissimilar two individuals may be, in a rank correlation sense, given that they agree completely on the desirability ordering of levels within attributes, but may disagree considerably regarding the importance they attach to the attributes themselves. The problem has interesting implications regarding the potential value of clustering individuals' utility functions for market segmentation or other such purposes.The authors would like to thank the editor and three anonymous reviewers for their excellent comments on an earlier draft of the paper.     

Sufficient Reason and Reason Enough

I offer an analysis of the Principle of Sufficient Reason and its relevancy for the scientific endeavour. I submit that the world is not, and cannot be, rational—only some brained beings are. The Principle of Sufficient Reason is not a necessary truth nor a physical law. It is just a guiding metanomological hypothesis justified a posteriori by its success in helping us to unveil the mechanisms that operate in Nature.     

Mixtures of Autoregressions with an Improper Component for Panel Data

An EM algorithm for fitting mixtures of autoregressions of low order is constructed and the properties of the estimators are explored on simulated and real datasets. The mixture model incorporates a component with an improper density, which is intended for outliers. The model is proposed as an alternative to the search for the order of a single-component autoregression. The methods can be adapted to other patterns of dependence in panel data. An application to the monthly records of income of the outlets of a retail company is presented.