Investigations on a pilot-plant contact digester for the treatment of a dilute urban waste

A pilot-plant contact digester treating an urban waste which approximated the BOD strength of domestic sewage was operated and the effect of loading and temperature, in the range 20° – 27°C, on performance was evaluated. Acclimatization of the digester to full loading is described and the upper limit of loading was determined. The problem of separation of sludge is also discussed.     

ConSERV, a project specific risk management concept

Managing risks in design intensive multi-disciplinary capital projects presents unique problems for decision makers within the project environment. Existing risk management tools, tend to employ axiomatic software and as such do not provide any intelligent risk management capability or lead to better informed decision making processes. ConSERV is being developed as a comprehensive project management methodology able to extract project specific risk issues throughout the project life cycle and apply experiential knowledge by using a knowledge-based system to assist in the management of them. A visual representation of the project risks is obtained by employing a more practical non probabilistic approach. ConSERV will provide project managers with on line decision support, at key stages of the project to assist in the management and control of the project specific risks identified.     

In vivo mutational analysis of the mupirocin gene cluster reveals labile points in the biosynthetic pathway: the "leaky hosepipe" mechanism

A common feature of the mupirocin and other gene clusters of the AT-less polyketide synthase (PKS) family of metabolites is the introduction of carbon branches by a gene cassette that contains a beta-hydroxy-beta-methylglutaryl CoA synthase (HMC) homologue and acyl carrier protein (ACP), ketosynthase (KS) and two crotonase superfamily homologues. In vivo studies of Pseudomonas fluorescens strains in which any of these components have been mutated reveal a common phenotype in which the two major isolable metabolites are the truncated hexaketide mupirocin H and the tetraketide mupiric acid. The structure of the latter has been confirmed by stereoselective synthesis. Mupiric acid is also the major metabolite arising from inactivation of the ketoreductase (KR) domain of module 4 of the modular PKS. A number of other mutations in the tailoring region of the mupirocin gene cluster also result in production of both mupirocin H and mupiric acid. To explain this common phenotype we propose a mechanistic rationale in which both mupirocin H and mupiric acid represent the products of selective and spontaneous release from labile points in the pathway that occur at significant levels when mutations block the pathway either close to or distant from the labile points.     

Discrete Blockage Detection in Pipelines Using the Frequency Response Diagram: Numerical Study

This paper proposes the use of fluid transients as a noninvasive technique for locating blockages in transmission pipelines. By extracting the behavior of the system in the form of a frequency response diagram, discrete blockages within the pipeline were shown to induce an oscillatory pattern on the peaks of this response diagram. This pattern can be related to the location and size of the blockage. A simple analytical expression that can be used to detect, locate, and size discrete blockages is presented, and is shown able to cater for multiple blockages existing simultaneously within the system. The structure of the expression suggests that the proposed technique can be extended to situations where system parameters may not be known to a high accuracy and also to more complex network scenarios, although future studies may be required to verify these possibilities.     

Effect of Solutes on Grain Refinement of As-Cast Fe-4Si Alloy

Metallurgical and Materials Transactions A - Grain size is one of the key microstructural factors that control the mechanical properties of steels. The present work aims to extend the theories of...     

Fabrication of microstructured polymer optical fibres

A methodology is presented suitable for the fabrication of a wide range of microstructured polymer optical fibres (mPOFs), a recent development where light guidance is achieved through the incorporation of a pattern of air channels that run the entire length of the fibre. We show that the key to good mPOF fabrication is a secondary draw oven that has tight control over the length (15–20 mm) and temperature (C) of the hot-zone while maintaining fibre draw tension high enough (50–150 g) to ensure an acceptable level of partial hole collapse (30–40%) due to surface tension effects. Diverse mPOFs with diameters in the range 200–1200 μm have been fabricated with typical standard deviations of 2–3 μm.     

Reduction of noise in AVHRR channel 3 data with minimum distortion

The channel 3 data of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA series of weather satellites (NOAA 6-12) are contaminated by instrumentation noise. The signal to noise ratio (S/N) varies considerably from image to image and the between sensor variation in S/N can be large. The characteristics of the channel noise in the image data are examined using Fourier techniques. A Wiener filtering technique is developed to reduce the noise in the channel 3 image data. The noise and signal power spectra for the Wiener filter are estimated from the channel 3 and channel 4 AVHRR data in a manner which makes the filter adaptive to observed variations in the noise power spectra. Thus, the degree of filtering is dependent upon the level of noise in the original data and the filter is adaptive to variations in noise characteristics. Use of the filtered data to improve image segmentation, labeling in cloud screening algorithms for AVHRR data, and multichannel sea surface temperature (MCSST) estimates is demonstrated. Examples also show that the method can be used with success in land applications. The Wiener filtering model is compared with alternate filtering methods and is shown to be superior in all applications tested