It is always stated that cakes formed under centrifugal fields have lower cake permeability than the cakes formed under gas pressure difference, but systematical investigations have not yet been ...published. Results are reported for two different suspensions from experiments carried out with both techniques under identical suspension conditions. A new standardized analysis method supported by cake flow‐through experiments is explained and allows the plotting of all results in the same diagram. For both suspensions, and contrary to the common belief, significantly higher cake permeability values for the laboratory centrifuge tests were determined. Explanations for this behavior are given.
A common assumption is that cakes formed under centrifugal fields exhibit lower cake permeabilities than those formed under gas pressure difference, but systematical investigations are still missing. Significantly contrary results are described and explained for experiments with two different suspensions using both techniques under identical suspension conditions.
Engineering design for structural safety is largely based on the statistics of natural hazards. These statistics are utilized by applying the theory of extremes, which predicts a cumulative ...distribution function of the extreme events. The parameters of this distribution are found by a fit to the historical extremes and the probabilities of potentially disastrous events are then calculated. It is pointed out here that this procedure often results in underestimation of the risk. This is because wrong probability plotting positions are widely used and because theoretical extreme value distributions are asymptotic only, so that in many cases they bring misleading information to the analysis. The means to avoid these problems in the extreme value analysis are outlined.
Discussion: BRADLEY JONES Jones, Bradley
Journal of quality technology,
04/2015, Letnik:
47, Številka:
2
Journal Article
Recenzirano
A discussion on normal plots of effects is presented. The author agrees with Russell Lenth, professor at the University of Iowa, that the use of normal or half-normal plots of effects is now ...outmoded. There are better analytical tools now available in commercial software for model selection in screening designs. His favorite for the analysis of unreplicated regular fractional factorial designs is Lenth's method as implemented in JMP using Monte Carlo simulation from the null model to obtain p-values for Lenth's pseudo-t statistic. There are several reservations about the Daniel plot. If many of the effects are active, it can miss more than one active effect. Plotting order statistics means that the plotted points are correlated, producing patterns that are easily misinterpreted. If there is a severe outlier or a missing observation, then the loss of that point makes the design nonorthogonal and then the Daniel plot is not applicable.
Highway alignment optimization based on cost minimization requires comprehensive formulation of costs sensitive to alignment and development of efficient solution algorithms. The complexity of the ...applicable cost functions severely limits the search algorithms that can be employed. Recently, genetic algorithms, which can search very effectively through complex spaces with huge numbers of local optima, have been successfully developed for highway alignment optimization. However, in order to solve real-world problems the optimization algorithms should work directly with a Geographic Information System (GIS) which stores relevant geographic information, such as land boundaries, environmentally sensitive regions, and topographic data. This paper presents a model for highway alignment optimization that integrates a GIS with genetic algorithms, examines the effects of various costs on alignment selection, and explores optimization in constrained spaces that realistically reflect the limits on road improvement projects. The paper integrates several previously published developments and adds some new analysis approaches. A real-world problem using a GIS database for Maryland is solved using the proposed method. An example using an artificial map to investigate the effectiveness of the proposed model in mountainous terrain is also demonstrated. The results indicate that travel-time cost, which is often neglected by highway agencies in selecting alignments, significantly affects the alignment optimization. Computation time increases significantly with the number of properties affected by each alignment. The model can optimize alignments in mountainous terrain or regions with very complex geography.
The dependence of the reaction rate on solvent dielectric constant is examined for the reaction of trihexylamine with 1-bromohexane in a series of 2-ketones over the temperature range 25–80 °C. The ...rate constant data are analyzed using the compensated Arrhenius formalism (CAF), where the rate constant assumes an Arrhenius-like equation that also contains a dielectric constant dependence in the exponential prefactor. The CAF activation energies are substantially higher than those obtained using the simple Arrhenius equation. A master curve of the data is observed by plotting the prefactors against the solvent dielectric constant. The master curve shows that the reaction rate has a weak dependence on dielectric constant for values approximately less than 10 and increases more rapidly for dielectric constant values greater than 10.
Mountain-block groundwater in the Southern Basin-and-Range Province shows a variety of patterns of δ18O and δ2H that indicate multiple recharge mechanisms. At 2420 m above sea level (masl) in Tucson ...Basin, seasonal amount-weighted means of δ18O and δ2H for summer are −8.3, −53‰, and for winter, −10.8 and −70‰, respectively. Elevation-effect coefficients for δ18O and δ2H are as follows: summer, −1.6 and −7.7 ‰ per km and winter, −1.1 and −8.9 ‰ per km. Little altitude effect exists in 25% of seasons studied. At 2420 masl, amount-weighted monthly averages of δ18O and δ2H decrease in summer but increase in winter as precipitation intensity increases. In snow-banks, δ18O and δ2H commonly plots close to the winter local meteoric water line (LMWL). Four principal patterns of (δ18O, δ2H) data have been identified: (1) data plotting along LMWLs for all precipitation at >1800 masl; (2) data plotting along modified LMWLs for the wettest 30% of months at <1700 masl; (3) evaporation trends at all elevations; (4) other patterns, including those affected by ancient groundwater. Young, tritiated groundwater predominates in studied mountain blocks. Ancient groundwater forms separate systems and mixes with young groundwater. Recharge mechanisms reflect a complex interplay of precipitation season, altitude, precipitation intensity, groundwater age and geology. Tucson Basin alluvium receives mountain-front recharge containing 50%–90% winter precipitation.
Using few cycle pulses, uniform-electric-field-ion imaging spectrometer and Dalitz plotting, we can identify two new stepwise processes, in the dissociation of the 3+ and 4+ states of N sub(2)O in ...intense few cycle pulses at 4 10 super(15) Wcm super(-2). We observe suppression of selective channels at longer pulse length, which we attribute to molecular dynamics on the 2+ state and the shape of the 3+ potential, which influences propagation of the dissociating wave packet.
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