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This digital document is a journal article from Journal of Aerosol Science, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Aerosol agglomerates are generated artificially for industrial use and unintentionally as air pollutants. Aerosol models are needed in efforts to control and/or minimize particle formation. The sectional method has been the most widely used method for solving the aerosol population balance equation. The fixed-sectional method suffers from numerical diffusion when dealing with surface growth. The moving-sectional method introduces much less numerical diffusion, but is not easily applied to spatially inhomogeneous phenomena. In this paper, we present a novel fixed-sectional method that can significantly reduce numerical diffusion. It is compared to the moving-sectional method and a good agreement is obtained. The error caused by numerical diffusion was found to increase with the ratio of characteristic coagulation time over the characteristic surface growth time. Incorporating the new methodology for solving surface growth, we develop an accurate and time-efficient sectional model for the formation and growth of aerosol agglomerates. Simultaneous nucleation, surface growth, coagulation, sintering, and primary particle obliteration by surface growth are incorporated in the model. The ''representative size'' method is used, and the numbers of agglomerates and primary particles in each section are selected as the two variables representing size distribution and structure of particles. Our model is used to simulate the titania particle synthesis in a premixed flame. The effect of primary particle obliteration due to surface growth is shown to be significant when surface growth is the main particle growth mechanism. ... Read more

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This digital document is a journal article from Journal of Hazardous Materials, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The behavior of nutrient release and adsorption from sediments was influenced by hydrodynamic disturbance significantly. The resuspension/sedimentation processes of sediment particles and phosphate adsorption in Taihu Lake were investigated under different disturbing intensity by utilizing simulative conditions. The effect of morphological characteristics of suspended particles on phosphate adsorption was also studied. In order to elucidate the characteristics of particles suspended by disturbance, the size and structure of particles during different time were monitored on-line by using photometric dispersion and particles image analysis. The method of fractal geometry to explore the morphology characteristics of particles was also used. The results showed that sediments suspended obviously and the phosphate concentration of overlying water decreased rapidly when strong disturbance was applied. Moreover, two different disturbing conditions, one was static condition without wind and the other was weak disturbing intensity with slow wind velocity, following heavy disturbance were compared, and it turned out that the turbidity and phosphate concentration were lower in the latter because the size and the structure of suspended particles were more favorable in the latter disturbing condition. The flocculation index of suspended particles was 0.25 and characteristic length was 30@mm under 100rpm disturbance; comparatively, when heavy disturbance increased to 120rpm, the flocculation index grew up to 0.60 and the characteristic length was greater than 60@mm. The fractal dimensions of suspended particles were between 1.65 and 1.92. ... Read more

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This digital document is a journal article from Journal of Aerosol Science, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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This paper presents a methodology to allow a real-time particle size spectrometer to produce a mass concentration output by calculation from its electrical mobility response. As part of this, a Bayesian statistical algorithm for parametrising spectral data from the Cambustion DMS500 in terms of a number of lognormal functions is outlined, allowing the nucleation and accumulation modes of a Diesel aerosol to be treated separately and also to reduce mass calculation noise and improve spectral resolution. Previous literature is combined with new experimental results to develop a size:mass power-law relationship for this instrument. The effective density as a function of size for this instrument is found to be closer to that for water droplets than equivalent relationships for DMA/SMPS measurements in the literature, therefore making DMS500 mass calculation less susceptible to error from liquid adsorbed on agglomerates. The technique is validated with two Diesel engines against the gravimetric methods of filter paper and Diesel particulate filter (DPF) weighings. Good agreement is achieved over a variety of engine conditions, with the mean and standard deviation of the percentage difference of the calculated mass concentration from DPF weighings being -12.1+/-11.4% and from filter paper weighings being -15.1+/-18.0%. The calculated mass concentrations are systematically below those of the gravimetric methods. ... Read more

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This digital document is a journal article from Journal of Aerosol Science, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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We show that soot formed in laminar diffusion flames of heavily sooting fuels evolves through four distinct growth stages which give rise to four distinct aggregate fractal morphologies. Each successive stage grows upon the previous stage; hence aggregates of one morphology, parameterized by a fractal dimension, form larger superaggregates or gels of a different morphology with a different fractal dimension. These results were inferred from large and small angle static light scattering from the flames, microphotography of the flames, and analysis of soot sampled from the flames. These results and the analysis were substantiated by comparison to computer simulations. The growth stages occur approximately over four successive orders of magnitude in aggregate size. Each growth stage is a fundamental physical process: Stages 1 and 3 are diffusion limited cluster aggregation in three and two dimensions, respectively; Stages 2 and 4 are percolation in three and two dimension, respectively. ... Read more

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This digital document is a journal article from Journal of Experimental Marine Biology and Ecology, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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We examined the spatial heterogeneity in three sessile rocky shore organisms, the mussel Perna perna, the barnacle Octomeris angulosa (Sowerby) and the red alga Gelidium pristoides (Turn.) at a range of continuous local scales along horizontal transects within mid- and upper mussel beds of South African shores. We also examined the relationships between variability of organisms and topographic features (rock depressions, slope, aspect), and between mussel, barnacle and algal variability over the same scales. To estimate spatial heterogeneity, we analyzed scaling properties of semivariograms using a fractal approach. Relationships between different variables at the different scales were examined by cross-semivariograms. Spatial dependence of P. perna variability increased with spatial dependence of topographic variability, so that scaling regions of mussel and topographic distributions corresponded well. This relationship often improved with larger local scales (mussel cover increased with depressions, steeper slope and aspect towards waves), while at smaller spatial scales, variability in mussel cover was less well explained by variability in topography. The variability of the barnacle O. angulosa exhibited spatial dependence, even on topographically unstructured shores. In contrast, the distribution of the alga G. pristoides revealed high fractal dimensions, showing spatial independence on topographically unstructured shores. Algae also showed a very strong negative relationship with mussels at most local scales, and a negative relationship with barnacles in upper zones, especially at larger local scales. Barnacles may show clear spatial dependence because of hydrodynamics (at larger local scales) and the need to find a future mate in close proximity (at smaller local scales), while algae may show a strong negative relationship with mussels because of competition for space. ... Read more

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This digital document is an article from Journal of the Alabama Academy of Science, published by Alabama Academy of Science on January 1, 2000. The length of the article is 325 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: REPRESENTATION OF ZETA AND MOBIUS FUNCTIONS AS TENSOR PRODUCTS OF MATRICES.(Brief Article)
Publication: Journal of the Alabama Academy of Science (Refereed)
Date: January 1, 2000
Publisher: Alabama Academy of Science
Page: 30

Article Type: Brief Article

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This digital document is a journal article from Chemical Engineering Journal, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Sludges are made of flocs produced during the coagulation stage. Their dewatering not only depends on the equipment used but also on the chemical, structural and physical characteristics of flocs. In this study, the relation between floc structure and sludge dewaterability is investigated beside the influence of the operating conditions during coagulation. Eight synthetic clay flocs families are produced using clay suspensions with four initial solids concentrations ranging from 0.5 to 5gL^-^1 and two coagulants (Al"2(SO"4)"3 and FeCl"3). Flocs structure is characterised by their fractal dimension and by the size of the basic units (clusters, aggregates) they are made from. Fractal dimension values about 2.5 are indicative of rather compact structures with slightly looser flocs obtained when using FeCl"3. Except for clusters, larger in ferric flocs, the basic units sizes are similar whatever the coagulant used and they decrease when the solids concentration during coagulation is increased. Sludge dewaterability is estimated from the bound water content and the capillary suction time (CST) giving respectively information on the extent and on the rate of water removal. Ferric flocs contain about 20% less bound water but exhibit higher CST values and therefore higher resistance to water removal than alum ones. Flocs structure and sludge dewaterability are found linked. The sludge bound water content is found to decrease with the floc fractal dimension: less compact flocs contain more water but less bound water. And the capillary suction time is lower when sludges are made of smaller flocs. ... Read more

Product Description
This digital document is a journal article from Chemical Engineering Journal, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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This study examined how the floc characteristics affect dewaterability of activated sludge. The floc properties were characterized by morphological parameters (floc size distribution, fractal dimension and filament index), physical properties (flocculating ability, surface charge, relative hydrophobicity and viscosity), and chemical constituents in sludge and extracted extracellular polymeric substances (EPS), including the polymeric compounds protein, humic substances, carbohydrates and the ions Ca^2^+, Mg^2^+, Fe^3^+ and Al^3^+. The dewaterability was defined in terms of the bound water content and capillary suction time (CST). The bound water and CST corresponded to a similar indication with respect to dewaterability of activated sludge. The floc physical parameters were the most important factors which effect significantly on the water binding ability of the sludge flocs. The morphological characteristics had relatively weak impact on the dewaterability. The polymeric components protein and carbohydrate had a significant contribution to enhance the water binding ability of the sludge flocs. The effect of humic substances in the sludge on the dewaterability was, however, insignificant. The CST had good statistical correlations with the polymeric constituents measured in both sludge and the extracted EPS, and the bound water was only correlated well with the individual polymers measured in the sludge. High concentration of Ca^2^+, Mg^2^+, Fe^3^+ and Al^3^+ had significant improvement for dewaterability. ... Read more

Product Description
This digital document is a journal article from Journal of Aerosol Science, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Hydrodynamic resistances of spheroidal porous agglomerates are calculated theoretically for circumstances when the flow is directed either parallel or perpendicular to their symmetry axes. Expressions for the equivalent mobility radii of oblate and prolate spheroids are calculated and generalized for wide ranges of particle porosities, sizes and fractal dimensions D"f. Aggregate shape and permeability are shown to have competitive effects on their mobility. Permeability has the strongest effect on the mobility radii of agglomerates with shapes close to spherical and for extremely porous structures. For fractal-like agglomerates, permeability has the strongest effects for low D"f structures, composed of about several hundreds of elementary particles. Mobility radii of these agglomerates are found to have fractal dimensions about 10% higher than the one that could be obtained from the geometrical size analysis. Large fractal agglomerates behave like impermeable bodies even if their average porosity is large. A similar behavior is characteristic of very small agglomerates, because their porosity is normally low. The calculated mobility radii are used for correlating the size-dependent free fall velocity of porous ice crystals. ... Read more

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This digital document is a journal article from Journal of Banking and Finance, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The scaling properties encompass in a simple analysis many of the volatility characteristics of financial markets. That is why we use them to probe the different degree of markets development. We empirically study the scaling properties of daily Foreign Exchange rates, Stock Market indices and fixed income instruments by using the generalized Hurst approach. We show that the scaling exponents are associated with characteristics of the specific markets and can be used to differentiate markets in their stage of development. The robustness of the results is tested by both Monte Carlo studies and a computation of the scaling in the frequency domain. ... Read more

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This digital document is an article from Journal of Soil and Water Conservation, published by Soil & Water Conservation Society on September 1, 1995. The length of the article is 2414 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

From the supplier: New models for describing soil hydraulic characteristics are described. The models are based on coupling fractal processes with the Marshall saturated conductivity formulation. These methodologies, which estimate soil matrix and macro-pore characteristics, are organized into a set of procedures which use varying levels of data input. The procedures do not require extensive field and laboratory data.

Citation Details
Title: Utilizing fractal principles for predicting soil hydraulic properties.(Special Issue: Water Research and Management in Semiarid Environments)
Author: W.J. Rawls
Publication: Journal of Soil and Water Conservation (Refereed)
Date: September 1, 1995
Publisher: Soil & Water Conservation Society
Volume: v50Issue: n5Page: p463(3)

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This digital document is a journal article from European Journal of Political Economy, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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This digital document is an article from Journal of Computer Science, published by Science Publications on May 1, 2008. The length of the article is 4045 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.

From the author: Key words: Zero-knowledge, cryptography, fractal, mandelbrot fractal set and julia fractal set

Citation Details
Title: Fractal (Mandelbrot and Julia) zero-knowledge proof of identity.
Author: Mohammad Ahmad Alia
Publication: Journal of Computer Science (Magazine/Journal)
Date: May 1, 2008
Publisher: Science Publications
Volume: 4Issue: 5Page: 408(7)

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This digital document is an article from FOCUS: Journal for Respiratory Care & Sleep Medicine, published by Focus Publications, Inc. on May 1, 2009. The length of the article is 1043 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser.

Citation Details
Title: Applying fractal geometry to mechanical ventilation.(STUDENT PAPERS)
Author: Carrie Walter
Publication: FOCUS: Journal for Respiratory Care & Sleep Medicine (Magazine/Journal)
Date: May 1, 2009
Publisher: Focus Publications, Inc.
Page: 46(2)

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Product Description
This digital document is a journal article from Journal of Aerosol Science, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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The hydrodynamic drag and thermophoretic properties of fractal-like aggregates of spheres in the free-molecular flow regime are examined using a Monte Carlo method. A modification of the sampling procedure that is used to assign velocities to the computational molecules is developed, and allows for a relatively fast and accurate determination of the particle transport properties for small-Mach number (i.e., slow-moving) conditions. Aggregate targets in the simulation are generated using an algorithm which mimics cluster-cluster aggregation, and simulations are performed on aggregates with a range of fractal dimensions and structure factors. The results indicate that for fractal dimensions in the range of D"f=1.7-2.0, the hydrodynamic radius of the aggregate scales as a"m~aN"S^0^.^4^7, in which a is the sphere radius and N"S is the number of spheres. Results also show that the thermophoretic velocity of a randomly-oriented aggregate will be slightly larger than that of the isolated spheres. The enhancement in velocity increases with N"S, yet for relatively large-scale aggregates with N"S=3000 the increase is only around a factor of 1.08. ... Read more

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This digital document is a journal article from Chemical Engineering Journal, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

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Focussed beam reflectance measurement is a technique that shows some promise as a technique for the online characterisation of floc size and structure. A scanning laser is focused into process fluid and the reflected intensity is measured as a function of time. This light intensity signal is normally processed to return chord length measurements which contain combined information on particle size and shape. This study shows that the unprocessed signal can be expected to encode information about the texture of the particle being scanned in addition to size and shape. For the purpose of characterising floc structure, a power law exponent can be recovered from the Fourier transform of the unprocessed signal and this in turn is related to the mass fractal dimension of flocs. The technique is demonstrated with computer generated flocs and with flocculated polystyrene latex of a primary particle size of 5@mm and a mass fractal dimension of D"m=2.5 as determined by the volume obscuration method. Results obtained through simulation studies into scanning of computer generated flocs demonstrate that a correlation exists between the power law exponent and the mass fractal dimension. Loose structures with mass fractal dimension of D"m=1.64 returned a power law exponent of @b=-l.77 whilst a tighter structure of mass fractal dimension of D"m=2.34 returned a power law exponent of @b=-1.92. Results obtained through scanning of polystyrene latex flocs of mass fractal dimension of D"m=2.49 returned a power law exponent of @b=-2.00 which appears not to be in quantitative agreement with the simulation results. ... Read more

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This digital document is an article from Forest Products Journal, published by Thomson Gale on May 1, 2007. The length of the article is 4408 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser.

Citation Details
Title: Fractal description of the water sorption behaviors of wood and bamboo under circular vacuum-pressure.
Author: B.H. Fei
Publication: Forest Products Journal (Magazine/Journal)
Date: May 1, 2007
Publisher: Thomson Gale
Volume: 57Issue: 5Page: 54(7)

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