Using computational fluid dynamics to modify a waste-heat boiler design

This article describes the use of a general-purpose computational-fluid-dynamics code for improving and optimizing waste-heat boilers in the Outokumpu flash smelting process. The codes offer opportunities to study the transport phenomena for fluid and particulate flow and heat and mass transfer. The simulation includes gas- and dust-flow behaviors and gas cooling by convection and radiation. The results were used in the boiler modification for increased capacity and higher cooling efficiency. The modified boiler, with its unique design, has been in use at Outokumpu’s Harjavalta copper smelter since June 1995 with excellent performance. For more information, contact Y. Yang, Delft University of Technology, Raw Materials Technology/Applied Earth Sciences, Mijnbouwstraat 120, Delft, 2628 RX, Netherlands; telephone 31-15-278-2542; fax 31-15-278-2836; e-mail Y.Yang@ta.tudelft.nl.     

The effect of saturation fluctuations on droplet growth

In the atmosphere the saturation ratio of water vapour varies as a function of time and space. In the present study we have investigated the effects of fluctuations of saturation ratio on droplet (cloud condansation nuclei) growth by stochastic approach employing an advanced growth model for cloud droplets. In saturated mean conditions growth of cloud droplets is accelerated by the fluctuations of saturation ratio, and our results indicate that due to fluctuations some droplets are able to grow in undersaturated conditions. Stochastic fluctuations of saturation ratio result in appearance of bimodal particle-size distribution and this is one of the possible explanations for the observed two modal cloud droplet distribution.     

Behavioral and neural characteristics of short-latency and long-latency conditioned responses in cats.

Studied head movements to a tone to the left ear (conditioned stimulus [CS]) in 6 cats. An attempt was made to differentiate an orienting, short-latency (alpha) response from the long-latency conditioned (delayed) response. The unconditioned stimulus (UCS) was a brain stimulation to the lateral hypothalamus eliciting a specific, stereotypical head movement. These behavioral characteristics of the unconditioned head movement were used for differentiating it from the conditioned short-latency head movement. Paired conditioning and randomly unpaired control sessions (5 daily sessions each) were given in balanced order to each S. Evoked neural responses in the hippocampus and cingulate cortex were recorded simultaneously to compare the time–amplitude characteristics of evoked responses to earlier findings in multiple-unit recordings. The results supported the differentiation of the behavioral responses. The time–amplitude course of the evoked neural responses showed complex changes, appearing as an increase in the negativity during the alpha-response period and as an increase in the positivity during the long-latency period on omitted-UCS (CS-alone test) trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alkaline fuel cell: A test plant,measurements and analysis of the results

An experimental study of an alkaline fuel cell test plant with a 0.5 kW fuel cell module is presented in this paper. The characteristics of the fuel cell module are measured in different steady state load conditions and with different electrolyte temperatures. The results are analysed by calculating the different efficiencies of the module.     

IN-LINE MEASUREMENT OF THE REFINING EFFECT-AN IMPORTANT NEW TOOL FOR USE IN THE PULP AND PAPER INDUSTRY

In the production of paper, pulp fibers are put through a refining stage. This greatly enhances the fiber characteristics and the resulting quality and properties of the paper that is being produced.

This paper outlines the various detailed processes which occur during the refining stage and what the resulting effects are on paper quality. It discusses the measurements of 'freeness' and 'drainage rate', which are used today as the primary means of measuring the'refining effect', and provides a brief evaluation of the effectiveness and limitations of these techniques.

With the Scanning Laser Microscope, one can now observe the 'refining effect' on a microscopic basis by analyzing the structure of individual fibers. In particular one can measure the changes in the mean fiber diameter and the amount of fines that are produced. These changes are measured on a statistically significant basis in real time and provide valuable information for control of the refining process itself.

This paper reports actual test results and provides a preliminary analysis of the significance of these results and how the findings could best be implemented in an actual control strategy for operating a refiner.     

Iceberg lettuce as suggested source of a nationwide outbreak caused by two Salmonella serotypes, Newport and Reading, in Finland in 2008

A nationwide outbreak of Salmonella enterica serotypes Newport and Reading occurred between 17 October and 28 November 2008 in Finland. A total of 77 culture-confirmed Salmonella Newport and 30 Salmonella Reading cases, including one case with a double infection, were reported. All strains isolated from the patients were subtyped using serotyping, microbial resistance profiling, and pulsed-field gel electrophoresis (PFGE). Here, the PFGE patterns of the studied Salmonella Newport strains were identical, whereas four different PFGE profiles were found among the Salmonella Reading strains. Two elderly patients died within 2 weeks of the onset of symptoms. Three geographical clusters of cases with an epidemiological link were identified. The traceback investigation suggested that the factor connecting the cases was ready-chopped iceberg lettuce available for mass catering use. However, none of the tested food, environmental samples, or the samples taken from the staff of the processing plant contained Salmonella bacteria. Tracing back to outbreak sources with a short shelf life can be complex.     

An industry experiment on the effects of test-driven development on external quality and productivity

Existing empirical studies on test-driven development (TDD) report different conclusions about its effects on quality and productivity. Very few of those studies are experiments conducted with software professionals in industry. We aim to analyse the effects of TDD on the external quality of the work done and the productivity of developers in an industrial setting. We conducted an experiment with 24 professionals from three different sites of a software organization. We chose a repeated-measures design, and asked subjects to implement TDD and incremental test last development (ITLD) in two simple tasks and a realistic application close to real-life complexity. To analyse our findings, we applied a repeated-measures general linear model procedure and a linear mixed effects procedure. We did not observe a statistical difference between the quality of the work done by subjects in both treatments. We observed that the subjects are more productive when they implement TDD on a simple task compared to ITLD, but the productivity drops significantly when applying TDD to a complex brownfield task. So, the task complexity significantly obscured the effect of TDD. Further evidence is necessary to conclude whether TDD is better or worse than ITLD in terms of external quality and productivity in an industrial setting. We found that experimental factors such as selection of tasks could dominate the findings in TDD studies.     

造纸企业清洁生产、环境保护进程与潜力

芬兰芬欧汇川集团是拥有100多年历史的可持续性发展的森林工业集团,是新型森林工业的引领者,采用了最佳可行技术,达到了最佳效率和最佳的业务表现,对环保的追求促进了公司不断进行新技术的创新和投资,以促进技术升级和公司业务的提升.     

Changes in content of microbially available phosphorus,assimilable organic carbon and microbial growth potential during drinking water treatment processes

There are regions where microbial growth in drinking water is limited by phosphorus instead of organic carbon. In phosphorus limited waters small changes in phosphorus concentration significantly affect microbial growth. We studied how water treatment processes in waterworks affect the availability of microbial nutrients and microbial growth potential in drinking water. The nutrients studied were assimilable organic carbon (AOCpotential) and microbially available phosphorus (MAP) which both were quantified by bioassays. Chemical coagulation, commonly used in surfacewater works, effectively removed AOCpotential and MAP. In contrast to activated carbon filtration, ozonation increased the concentrations of AOCpotential and MAP, and also microbial growth potential. In most of the drinking waters, microbial growth was limited by phosphorus, and microbial growth potential correlated with the MAP concentration. Microbial growth potential was lowest in drinking waters produced from surface waters with efficient treatment technique and highest in less treated ground waters.     

Numerical investigation of 3-D constraint effects on brittle fracture in SE(B) and C(T) specimens

Specimen size and geometry effects on cleavage fracture of ferritic steels tested in the ductile-to-brittle transition region remain an important technological impediment in industrial applications of fracture mechanics and in the on-going development of consensus fracture testing standards. This investigation employs 3-D nonllinear finite element analyses to conduct an extensive parametric evaluation of crack front stress triaxiality for deep notch SE(B) and C(T) specimens and shallow notch SE(B) specimens, with and without side grooves. Crack front conditions are characterized in terms of J-Q trajectories and the constraint model for cleavage fracture toughness proposed previously by Dodds and Anderson. An extension of the toughness scaling model suggested here combines a revised in-plane constraint correction with an explicit thickness correction derived from extreme value statistics. The 3-D analyses provide effective thicknesses for use in the statistical correction which reflect the interaction of material flow properties and specimen aspect ratios, a/W and W/B, on the varying levels of stress triaxiality over the crack front. The 3-D computational results imply that a significantly less strict size/deformation limit, relative to the limit indicated by previous plane-strain computations, is needed to maintain small-scale yielding conditions at fracture by a stress-controlled, cleavage mechanism in deep notch SE(B) and C(T) speciments. Moreover, the analyses indicate that side grooves (20 percent) should have essentially no net effect on measured toughness values of such specimens. Additional new results made available from the 3-D analyses also include revised -plastic factors for use in experimental studies to convert measured work quantities to thickness average and maximum (local) J-values over the crack front. To estimate CTOD values, new m-factors are included for use in the expression 131-1.