A computational algorithm for catalysts experiencing concentration‐dependent deactivation

Abstract

A computational algorithm is proposed for catalyst pellets or reactors experiencing concentration‐dependent deactivation. In the integration of the deactivation equation in each time interval, the concentration of poison, reactant or/and product is considered to be a constant. The value of concentration is recalculated from the mass balance equation before integrating the deactivation equation. By such an approach, the number of equations is reduced; thus a two‐dimensional problem can be converted to a single‐dimensional one.     

Extraction of Bitter Acids from Hops and Hop Products Using Pressurized Solvent Extraction (PSE)

The EBC method 7.7, currently used for determination of bitter acids in hop products, is a time‐consuming and laborious extraction technique. In this paper, our aim was to propose a new extraction method based on Pressurized Solvent Extraction (PSE) sometimes also called Pressurized Fluid Extraction (PFE) or Accelerated Solvent Extraction (ASE). Compared to conventional extractions, PSE offers a number of important benefits. PSE on OnePSE^® automated extractor was used for extraction of α‐ and β‐acids from hops and hop products and the parameters influencing extraction efficiency and the influence of the sample preparation method were studied. The quantitative determination of α‐ and β‐acids in the extracts was accomplished by using an HPLC apparatus equipped with diode array detector. The experimental results were compared with those obtained by the standard EBC 7.7 method and the two methods were found to be fully compatible     

Using Faster Gas Chromatography Analyses in Brewing Analytics

Dominant trends in analytical chemistry include miniaturization in sample preparation techniques and faster run times to provide high‐throughput screening, fast process monitoring and fast method development. This study focused on the application of narrow bore gas chromatographic capillary columns, 0.18 mm internal diameter, for brewing analyses. On these capillary columns, faster analyses could be performed compared to conventional GC capillary columns using 0.32 to 0.53 mm internal diameters. The robustness of the state‐of‐the‐art faster capillary gas chromatography, without compromising resolution, has been demonstrated with the analyses of beer flavour compounds such as lower and higher alcohols, esters and other volatile compounds such as acetaldehyde and dimethyl sulphide in beer. These methods were able to reduce sample run times by 60%.     

Metal–Nonmetal Transition in Rubidium Tungsten Bronze RbxWOy

An oxygen concentration dependent metal–nonmetal (MN) transition was observed for Rb_0.23WO _y with 2.80 < y < 3.08. As 2.80 < y < 3.0, the room temperature resistivity (_RT) of the Rb_0.23WO _y is about 5 × 10^–4 cm. While in the case of y > 3.04, the _RT of the Rb_0.23WO _y exhibits a four orders of magnitude increase with a value of 5 cm. Correspondingly, the lattice constant along c-direction slightly shortens as oxygen concentration increases from 2.80 to 3.08. The observed results suggest that the hybridization between W 5d (t_2g) and O 2p orbitals might be responsible for the MN transition. In addition, similar measurements were performed for Rb _x WO_3.04 and Rb _x WO_2.85 with 0.19 < x < 0.27. No rubidium concentration dependent MN transition was observed, indicating the electronic structure of the host WO _y is not modified significantly by varying the soluble rubidium concentration.     

Measuring neutron noise induced by travelling air bubbles in a research reactor

Travelling air-bubble experiments carried out in a research reactor confirm an earlier proposed model. The sink structure could be found experimentally in the APSD of neutron signals and was used to determine the bubble velocity. The measurements show that neutron detectors measure the velocity of the travelling bubbles, the thermocouples that of the water flow.     

Interaction of zinc oxide with bismuth oxide

The lattice parameters of polycrystalline ZnO in mixtures of ZnO-Bi₂O₃ and their dependence on Bi₂O₃-concentration were determined. Simultaneously the influence of ZnO presence on the origin of various modifications of Bi₂O₃ was observed. On the grounds of the measured decrease of the elementary cell volume the supposition about the interaction of Zn-intersititals with overstoichiometric oxygen atoms in Bi₂O₃ was accepted. In accordance with this idea the changes of free carrier concentration of samples ZnO+5 mol% Bi₂O₃ in the dependence on annealing temperature were found.     

A fast and simple algorithm for computing the longest common subsequence of run-length encoded strings

Let X and Y be two strings of lengths n and m, respectively, and k and l, respectively, be the numbers of runs in their corresponding run-length encoded forms. We propose a simple algorithm for computing the longest common subsequence of two given strings X and Y in O(kl+min{p₁,p₂}) time, where p₁ and p₂ denote the numbers of elements in the bottom and right boundaries of the matched blocks, respectively. It improves the previously known time bound O(min{nl,km}) and outperforms the time bounds O(kllogkl) or O((k+l+q)log(k+l+q)) for some cases, where q denotes the number of matched blocks.     

Building Knowledge for Substation-Based Decision Support Using Rough Sets

This paper describes a new technique based on rough sets to extract decision rules from large volumes of data captured by protection, control, and monitoring intelligent electronic devices. The methodology correctly identifies faults from large datasets and could be used to assist operators in their decision-making processes. Building knowledge for a fault diagnostic system is a time-consuming and costly process. The quality of a knowledge base can sometimes be hampered by a large number of superfluous decision-making rules that can lead to an unnecessarily large knowledge base system and inefficient or even detrimental rule maintenance. The methodology proposed cannot only induce decision rules efficiently but can also reduce the size of the knowledge base without causing loss of useful information. Results can be used by an expert system to generate supervisory automation and to support operators, for example, during an emergency situation. This methodology involves the generation of human-machine interface alarms. These can then be used for diagnosis of the type and cause of a fault event to give suggestions for network restoration and post-emergency repair. A power systems computer aided design/electromagnetic transients including dc simulator has been used to investigate the effect of faults and switching actions on the protection and control equipment associated with a typical distribution network. The fundamental ideas of rough set theory are discussed, followed by a rule assessment method that is outlined using an illustrative example.