Mechanism of the skeletal isomerisation of linear butenes over ferrierite: analysis of side reactions

An investigation of the effect of reaction conditions on product distribution in the skeletal isomerisation reaction of linear butenes has been carried out. The main reaction routes over ferrierite have been identified. Beside the main product isobutene, major by-product formation occurs. The unwanted reactions include dimerisation of butene to form octenes, hydrogen transfer yielding small amounts of saturated C₃ and C₄ hydrocarbons and disproportionation producing propene and pentenes. The most abundant by-products were pentene and propene, though these were not formed in equimolar amounts as could be expected. Oligomerisation experiments of propene over ferrierite produced large amounts of butene and pentene, revealing the presence of adsorbed nonene. The cracking of this surface species to hexene and propene is the most likely reaction route for the excess propene formation. This additional path to propene formation operates mainly at temperatures above 623 K.     

数字图像的质量评价

图像质量评价的使用已成为图像信息工程的基础技术之一。本文对目前一些典型的数字图像质量介方法进行了简要综述,并着重介绍了一种基于视觉兴趣的图像质量评价方法,最后指出了图像质量评价研究可能发展的方向。     

Overview of a Modal-Based Condition Assessment Procedure

Condition assessment is a term that is used to describe the process of characterizing the physical condition of constructed systems. This paper summarizes a condition assessment (CA) procedure based on a complete system of field-testing, finite element (FE) modeling, and load rating. Experimental techniques, including both modal testing and truckload testing, are used to collect measurements of the constructed systems. The basic mechanism and procedure of the FE modeling and calibration are presented. Different physical parameters of FE models are adjusted during the calibration process using both static and dynamic responses as criteria to achieve convergence between experimental measurements and analytical results using carefully developed objective functions. Finally, a bridge load rating is completed on the basis of the calibrated model. These developments are described and illustrated using a representative bridge as an example.     

Structured literature image finder: Parsing text and figures in biomedical literature

The SLIF project combines text-mining and image processing to extract structured information from biomedical literature.SLIF extracts images and their captions from published papers. The captions are automatically parsed for relevant biological entities (protein and cell type names), while the images are classified according to their type (e.g., micrograph or gel). Fluorescence microscopy images are further processed and classified according to the depicted subcellular localization.The results of this process can be queried online using either a user-friendly web-interface or an XML-based web-service. As an alternative to the targeted query paradigm, SLIF also supports browsing the collection based on latent topic models which are derived from both the annotated text and the image data.The SLIF web application, as well as labeled datasets used for training system components, is publicly available at http://slif.cbi.cmu.edu.     

Net energy analysis of district solar heating with seasonal heat storage

A net energy analysis of district solar heating using seasonal heat storage has been performed. The use of seasonal heat storage is of great importance in northern latitudes when the solar contribution is to be increased. Different system alternatives were considered. Net energy ratios for the most favourable options were found to be between 3 and 5.     

Investments into forest biorefineries under different price and policy structures

Increasing scarcity of oil reserves and the high CO₂ emissions from using oil have contributed to the development of renewable biofuels. Pulp and paper mill integrated forest biorefineries offer one important means to increase biofuel production. This study analyzes the effects of policies to support biofuel production in the pulp and paper sector. We study the relative effectiveness of three biofuel supporting policy instruments, namely production subsidy, input subsidy and investment subsidy. We present a partial equilibrium pulp and paper market model with a biorefinery investment option. A numerical model is used to evaluate the impacts of policy instruments on wood prices, as well as input choices and investment strategies of pulp and paper industries. The data represent the Finnish pulp and paper sector. We evaluate the values and direct costs of the policy instruments in a situation of exogenous biofuel production targets. The direct costs of input and investment subsidies are higher than those of a production subsidy. With all the policy instruments, Finnish pulp and paper mills would invest in wood-gasifying technology, instead of black liquor based one. The number of biorefinery units is dependent on the subsidy type — investment and input subsidies are likely to result in more numerous but smaller biofuel production units than a production subsidy. With all the policy instruments the demand for wood increases in Finland leading to higher wood prices. This, in turn, could reflect negatively on the profitability of the pulp and paper industries. To a significant degree, the model and the results can be generalized to other countries and markets where integrated pulp and paper mills are operating.     

Chloride-induced stress corrosion cracking of Duplex stainless steels. Models,test methods and experience

Stress corrosion cracking (SCC) induced by chlorides frequently causes problems in applications where standard austenitic stainless steels are being used. Often this problem can be solved by the use of duplex stainless steels. In this report the mechanisms for SCC have been surveyed, and the cause for the high SCC resistance of duplex stainless steels has been discussed and evaluation of test methods for SCC and how duplex stainless steels respond to them, as well as practical experience of duplex stainless steels. The study shows that no single mechanism can be attributed to the good resistance to SCC of duplex stainless steels. Probably a synergistic effect of electrochemical and/or mechanical effects is responsible for the good performance. Test methods for SCC often give relatively good correspondence with real applications, but ranking is often doubtful, and comparisons of different material types should be made with caution. Numerous cases with SCC on standard austenitic stainless steels have been solved by the use of duplex stainless steels.     

Cadmium Purification with a Vibrating Reactor

This paper describes the results of pilot plant testwork on a novel single stage zinc solution purification process using a vibratory reactor. This technique was modified for continuous cadmium cementation. There are distinct advantages to combining an intensely agitated reactor with a high mass of precipitant per unit volume in the form of granular zinc instead of zinc dust, including significant reduction of cementation agent consumption and substantial upgrading of the cadmium cement. This technique has the potential to minimize equipment, reduce plant size, and diminish operating costs.