从限额设计谈投资控制

文章根据设计阶段投资控制的现状及存在问题,提出只有在设计行业全面推行限额设计,深化设计阶段的投资控制工作,才能从根本上体现全过程投资控制的理念,提高投资控制效果,节约建设工程总投资。     

A hexane solution deposition of SnS2 films from tetrabutyltin via a solvothermal route at moderate temperature

SnS₂ films have been deposited on glass and alumina plate substrates by the reactions between an organotin precursor [tetrabuyltin, (CH₂CH₂CH₂CH₃)₄Sn] and carbon disulfide in n-hexane at the temperature range 180-200 °C for 10-40 h. The reaction system was oxygen free and applied at a moderate temperature. The films so prepared were characterized by techniques of X-ray diffraction, Scanning electron microscopy, Raman and Mössbauer spectroscopies. The films deposited on glass as well as on alumina plate have an average thickness of 30 μm, but have different rose-like morphologies, which are influenced by both the anisotropic growths of crystals and the different substrate structures. Photoluminescence measurements show that the films have an emission peak at approximately 590 nm.     

The combustion of kerosene: Experimental results and kinetic modelling using 1- to 3-component surrogate model fuels

The oxidation of kerosene Jet-A1 and that of n-decane have been studied experimentally in a jet-stirred reactor at atmospheric pressure and constant residence time, over the high temperature range 900–1300 K, and for variable equivalence ratio (0.5≤ϕ≤2). Concentration profiles of the reactants, stable intermediates, and final products have been obtained by probe sampling followed by on-line and off-line GC analyses. The oxidation of neat n-decane and of kerosene in these conditions was modeled using a detailed kinetic reaction mechanism (209 species and 1673 reactions, most of them reversible). The present model was successfully used to simulate the structure of a fuel-rich premixed n-decane–oxygen–nitrogen flame. In the modelling, kerosene was represented by four surrogate model fuels: 100% n-decane, n-decane-n-propylbenzene (74%/26% mol), n-decane-n-propylcyclohexane (74%/26% mol), and n-decane-n-propylbenzene-n-propylcyclohexane (74%/15%/11% mol). The 3-component model fuel was the most appropriate for simulating the JSR experiments. It was also successfully used to simulate the structure of a fuel-rich premixed kerosene–oxygen–nitrogen flame.     

Growth and morphology of nanometer LiMn2O4 powder

The growth of Li_1+xMn₂O₄ via detonation reaction was investigated with respect to the presence of an energetic precursor, such as the metallic nitrate and the degree of confinement of the explosive charge. The detonation products were characterized by scanning electron microscopy. Powder X-ray diffraction and transmission electron microscopy were used to characterize the products. Li_1+xMn₂O₄ with 1-2 μm spherical morphology and more uniform secondary particles, but with smaller primary particles of diameters from 20 to 60 nm and a variety of morphologies were found. The oxides produced by this cheap method affirmed the validity of detonation synthesis of nano-size powders.     

基于决策树技术的日前市场清算电价预测

以澳大利亚昆士兰州电力市场为背景,采用决策树技术,建立了提前日的电力市场清算电价预测模型。详细介绍了决策树技术的原理及其在电价预测中的实现方法,考虑了非电价因素对电价预测的影响。实际结果表明该方法具有良好的预测效果和直观性。     

Intrusion detection in web applications using text mining

Information security has evolved from just focusing on the network and server layers to also include the web application layer. In fact, security in some types of web applications is often considered a particularly sensitive subject. Achieving a secure web application involves several different issues like encrypting traffic and certain database information, strictly restricting the access control, etc. In this work we focus on detecting attempts of either gaining unauthorised access or misusing a web application. We introduce an intrusion detection software component based on text-mining techniques. By using text categorisation, it is capable of learning the characteristics of both normal and malicious user behaviour from the log entries generated by the web application server. Therefore, the detection of misuse in the web application is achieved without the need of any explicit programming or code writing, hence improving the system maintainability. Because telemedicine systems are usually critical in terms of the confidential information handled and the responsibilities consequently derived, we apply and evaluate our methods on a real web-based telemedicine system called Arnasa.     

Flammability ranking of foliage species by factor analysis of physical and chemical pyric properties

In this paper, factor analysis is introduced to evaluate the flammability of 55 foliage species that may be used in China for construction of the fuel break network of forest strips with lower flammability. Six pyric parameters, i.e. air dry moisture content, absolute dry moisture content, ignition point, ash content, caloric value and extractive content, are measured and used as variables for factor analysis. The covariance analysis shows that four principal factors can be extracted to reflect the flammability in different physical and chemical senses. In terms of the contributions of the four factors to the variances and the physical significance of the relevant parameters, the four factors are, respectively, termed as ‘flaming factor,’ ‘air dry factor,’ ‘ash factor’ and ‘absolute dry factor.’ The stability of the factor analysis method is examined by a different number of samples considered, and the variation degrees of the orderings indicate that the method has high reliability to measure the total flammability of foliage species. The results of the flammability evaluation are verified by comparison with the recommended tree species in the Chinese technology standard. Copyright © 2008 John Wiley & Sons, Ltd.     

Fouling study of silicon oxide pores exposed to tap water

We report on the fouling of Focused Ion Beam (FIB)-fabricated silicon oxide nanopores after exposure to tap water for two weeks. Pore clogging was monitored by Scanning Electron Microscopy (SEM) on both bare silicon oxide and chemically functionalized nanopores. While fouling occurred on hydrophilic silicon oxide pore walls, the hydrophobic nature of alkane chains prevented clogging on the chemically functionalized pore walls. These results have implications for nanopore sensing platform design.