探究信息技术在建筑工程管理中的应用

我国社会经济的全面发展需要社会各行业的综合进步,建筑行业作为我国传统支柱行业,其发展的重要性不言而喻.计算机信息技术的快速发展使得其在建筑行业得到了认可.为了加快建筑行业发展脚步,实现经济的综合发展,加强信息技术在建筑行业的应用探讨意义重大.建筑行业在新的社会环境中出现新的发展问题,面对问题采用积极的应对策略至关重要.论文针对信息技术在建筑工程管理中的应用进行简要分析,探究改善提高我国建筑工程管理的具体对策.     

Collapse analysis of real RC spatial structures using known failure schemes of ferro‐cement shell models

Large‐span reinforced concrete (RC) shells collapses that occurred in the last decade caused many death toll as well as significant losses to national economies. The most famous cases were the collapse of the aqua park cover in Moscow on February 2004 and the 2E terminal roof destruction at Charles de Gaulle Airport near Paris on May 2004. Following the publications of the appropriate commissions that have studied the reasons of these events, the influence of concrete creep and changes in the shell geometry on buckling of RC thin‐walled shells was not properly considered in the design. This study is focused on buckling of such shells, taking into account geometrical and physical nonlinear behaviour of compressed concrete. Other important reasons of concrete shells collapse are also analysed. The study is based on available experimental and theoretical investigations of ferro‐cement shells' models previously performed by the first author. The results of these investigations, obtained for small‐scale ferro‐cement models of thin‐walled shallow RC shells, are discussed. Behaviour of the tested models is compared with that of the above‐mentioned real shells and similar structures, which also collapsed. The critical buckling loads for the shells are obtained. It is shown that these loads are lower than the actual ones; thus, the shells buckling was unavoidable. To prevent brittle shell failure, they should be designed using other dominant failure modes that appear before the buckling. Possible failure schemes of real RC shells can be predicted using dominant failure modes obtained by laboratory testing of scaled models. Copyright © 2012 John Wiley & Sons, Ltd.     

空调负荷的神经计算法

提出了一种新的空调负荷计算方法－空调负荷神经计算法，介绍了其概念，原理及方法。     

问题式教学在“食品工程原理”教学中的应用

问题式教学是以问题为中心来处理教材和组织教学的一种教学方法,是通过引导学生产生问题、思考问题、回答和解决问题从而培养学生主动获取专业知识的能力,问题式教学可提高学生的学习能力、动手实践能力和探索创新能力。本文以食品科学与工程专业教学实践为例,在食品工程原理课程教学中对这种教学模式进行了探索,取得了良好的效果。     

An Unexpected Construction of 2‐Arylquinolines from N‐Cinnamylanilines through sp3 C?H Aerobic Oxidation Induced by a Catalytic Radical Cation Salt

An unexpected reaction of cinnamylanilines was achieved through the radical cation salt‐induced aerobic oxidation of sp³ C H bonds, providing a series of 2‐arylquinolines. The mechanistic study shows that the cinnamylaniline was oxidized to an imine, which was attacked by the aniline generated through decomposition of the corresponding imine. After further intramolecular cyclization and aromatization, 2‐arylquinolines were obtained. This reaction provides a new method to construct 2‐arylquinolines from readily accessible starting materials.

     

Assembly of Enantioenriched cis‐3a,8a‐Hexahydropyrrolo[2,3‐b]indole Scaffolds by Silver(I)‐Catalyzed Asymmetric Domino Reaction of Isocyanoacetates in the Presence of Cinchona‐Derived Chiral Phosphorus Ligands

By using Cinchona‐derived chiral phosphines as catalytic ligands, enantioenriched cis‐3a,8a‐hexahydropyrrolo[2,3‐b]indoles (ent‐HPIs), which are core scaffolds in a large array of biologically active natural products, can be convergently assembled under mild conditions through the silver(I)‐catalyzed asymmetric domino reaction of readily available isocyanoacetates and 2‐(2‐aminophenyl)acrylates. Various functionalities can be tolerated in the reaction, affording enantioenriched HPIs in high overall yields and good enantioselectivities (up to 92% ees).

     

Convergent Activation Concept for CO2 Fixation in Carbonates

Concepts to facilitate the conversion of epoxides with carbon dioxide to the corresponding cyclic carbonates commonly focus on the activation of the epoxide. Herein we report a catalytic system which allows the simultaneous activation of carbon dioxide and the epoxide. This convergent activation concept is realized by combining a suitable carbene as catalyst for the carbon dioxide activation with a second catalytic system based on potassium iodide for epoxide activation. Initial experiments showed synergistic effects and thus proving the feasibility of this activation concept. Moreover a standard protocol was developed and the substrate scope under these conditions has been studied. Under mild and solvent‐free conditions 14 epoxides could be converted. The respective cyclic carbonates were obtained in good to excellent yields with selectivities ≥ 99 % after simple filtration.

     

Palladium and Copper Cocatalyzed Intermolecular Cyclization Reaction: Synthesis of 5‐Aminopyrazole Derivatives

A novel and efficient palladium and copper co‐catalyzed intermolecular cyclization of acetonitriles with hydrazones has been developed for the synthesis of 5‐aminopyrazoles through C C and C N bond formation. The reaction has the advantages of easily available starting materials, simple manipulation and mild reaction conditions. The reaction involving various substituted acetonitriles and hydrazones proceeds smoothly and 5‐aminopyrazoles are synthesized in good yields. In contrast to the aliphatic and heteroaromatic substrates, the aromatic substrates tend to have a higher degree of reactivity.

     

Efficient Metal‐Free Aerobic Photooxidation of Sulfides to Sulfoxides Mediated by a Vitamin B2 Derivative and Visible Light

We have developed a metal‐free process for the aerobic photooxygenation of sulfides to sulfoxides mediated by riboflavin tetraacetate or riboflavin (vitamin B₂) photocatalysts and visible light (450 nm) in an acetonitrile‐water (85:15 v/v) mixture. The optimised solvent system leads to both singlet‐oxygen and electron‐transfer pathways in photooxygenation, thus allowing oxidation of electron‐poor and electron‐rich thioanisoles, dialkyl sulfides and sterically hindered sulfides. Besides having a broad substrate scope, the method has very short reaction times and requires low catalyst loading (down to 0.1 mol%). These properties are due to the high photocatalyst stability and the extremely high quantum yields (1.3 for thioanisole oxygenation). Moreover, the method is chemoselective, producing only sulfoxides without overoxidation to sulfones. Taking into account the broad substrate scope, high selectivity and high efficiency, this method distinguishes itself from those previously reported. Other advantages include easy work‐up of the reaction mixture, the availability and biodegradability of the photocatalysts and mild reaction conditions. We demonstrated, on a preparative scale, its practical application in the synthesis of the psychostimulant modafinil, in the selective oxidation of methionine derivatives, and in the detoxification of mustard gas.

     

Metal‐Free Autoxidative Nitrooxylation of Alkenyl Oximes with Molecular Oxygen

A metal‐free aerobic autoxidative nitrooxylation of alkenyl oximes mediated by tert‐butyl nitrite is described. Molecular oxygen is used as the oxidizing reagent, avoiding use of organic trapping reagents such as 2,2,6,6‐tetramethylpiperidine 1‐oxyl (TEMPO). The desired products were obtained in generally high yields.