Improving fairness of TCP Vegas

TCP Vegas exhibits fairness problems even for flows with the same round‐trip time (RTT). We propose an enhanced Vegas with three revisions, replacing BaseRTT with RTT, detecting how fast acknowledgements return and the acceleration of the return speed. The impacts of each of the three proposed revisions are not ignorable. The proposed novel Vegas with the three revisions, called EVA, achieves better fairness under various network conditions. Copyright © 2004 John Wiley & Sons, Ltd.     

Prediction of High Methane-Recovery Regions and Gas Extraction Technology Based on Geodynamic Zoning of Bowels

An analysis is performed for the existing hypotheses and theories used for calculating the technological parameters of operations on methane extraction from coal seams. The priority of geodynamic processes in methane collector formation, as well as the methods applied for the morphometry and processing of the remote probing data are substantiated. The urgency is shown for the investigation into the autooxidation and other exothermic reactions proceeding in coal seams and leading to methane transition to the free state.     

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.     

Characterization of particulate emissions from occupant activities in offices

This paper characterizes the relationship between occupant activities and indoor air particulate levels in a non-smoking office building. Occupant activities were recorded on video. Particulate concentrations were monitored by three optical particle counters (OPCs) in five size ranges at three heights. Particulate mass concentrations were measured gravimetrically and bioaerosol concentrations were determined by impaction methods. Occupant activities and number concentrations were determined with 1-min resolution over a 1-week period. Occupant activities such as walking past or visiting the monitoring site explained 24-55% of the variation of 1- to 25-micron diameter particle number concentrations. Statistical models associating particulate concentrations with occupant activities depended on the size fraction and included an autocorrelative term. Occupant activities are estimated to contribute up to 10 micrograms m-3 in particulate concentrations per person. Number concentrations of particles smaller than 1 micron had little correlation with indoor activities other than cigarette smoking and were highly correlated with outdoor levels. The method can be used to characterize emissions from activities if rapid measurements can be made and if activities can be coded from the video record.     

An extension of ASM2d including pH calculation

This paper presents an extension of the Activated Sludge Model No. 2d (ASM2d) including a chemical model able to calculate the pH value in biological processes. The developed chemical model incorporates the complete set of chemical species affecting the pH value to ASM2d describing non-equilibrium biochemical processes. It considers the system formed by one aqueous phase, in which biochemical processes take place, and one gaseous phase, and is based on the assumptions of instantaneous chemical equilibrium under liquid phase and kinetically governed mass transport between the liquid and gas phase. The ASM2d enlargement comprises the addition of every component affecting the pH value and an ion-balance for the calculation of the pH value and the dissociation species. The significant pH variations observed in a sequencing batch reactor operated for enhanced biological phosphorus removal were used to verify the capability of the extended model for predicting the dynamics of pH jointly with concentrations of acetic acid and phosphate. A pH inhibition function for polyphosphate accumulating bacteria has also been included in the model to simulate the behaviour observed. Experimental data obtained in four different experiments (with different sludge retention time and influent phosphorus concentrations) were accurately reproduced.     

Contact flocculation-filtration of humic substances

Contact flocculation-filtration of humic dispersions with alum in medium grain (0.62 mm) sand gave short runs to breakthrough, while in coarse (1.2 mm) media clarification was inefficient. Alum with cationic polymer gave in coarse media acceptable runs, but shorter then for mineral dispersions. Analysis of results by parameters of existing filtration models showed that using the Ives-Iwasaki model and plotting filtration coefficient λ vs specific deposit σ gave different λ_max for different polymer dose, plot of λ_max vs dose goes through maximum at optimum dose.Plotting the cube root of headloss vs square root of specific deposit gave a straight line corresponding to Shektman formula.Analysis by Adin-Rebhun model showed that for contact flocculation-filtration humic dispersions attachment coefficient k₁ was similar to, detachment k₂ was many fold higher then and theoretical maximum mass capacity much lower then in case of mineral dispersions.Calculations showed that the solid content and the density of alumo-organic deposits in bed are much lower than of alumo-mineral deposits. Polymers and minerals increase the solid content, the density of deposits and the mass capacity of filter beds.     

Attitudes towards regionalism in a rapid growth suburb

A key issue confronting our newer suburbs is the stance they should take towards efforts at regional cooperation and coordination of major policy areas. This article analyzes the preferences on this issue held by residents in a rapid growth suburb in the St. Louis metropolitan area. Through factor analysis, four identifiable dimensions of regionalist preferences were obtained from questionnaire responses--administrative cooperation, land-use cooperation, mass transit cooperation, and regional basic services cooperation. Correlational analyses between these dimensions of regionalist preferences and selected community status characteristics, social situation characteristics, and local political participation status of respondents reveal no systematic covariation. Thus municipal policies which influence the population mix within a community with respect to the life situation characteristics measured in this study are not likely to be useful instruments for influencing the preferences, pro or con, of the community towards regionalist policies. Further, local political participants are found to be representative of the larger community's regionalist policy preferences.