The packing of solid particles is an important research topic in particle mechanics and powder technology. However, it is difficult to predict and measure the packing density of particles. Although theoretical models for prediction and test methods for measurement have been developed, the predicted values and measured results do not always agree with each other. Through in-depth review of the theoretical predictions by the existing 2-parameter model and the respective measured results, it is postulated in this thesis that the discrepancies between the predicted values and measured results are mainly due to the wedging effect – a new interaction effect that has not been considered in previous packing models. The wedging effect occurs when some isolated fine particles are entrapped at the gaps between the coarse particles or when the gaps between the coarse particles are not wide enough for the formation of complete layers of fine particles. Such wedging effect would reduce the packing density and therefore should be considered in particle packing modeling. To provide additional measured results covering a wider range of size ratio than those published by others, a comprehensive experimental study of measuring the packing densities of binary mixes of mono-sized and rounded particles has been conducted. The wedging effect was further explained and more importantly quantified in the light of these experimental results. And, by incorporating the wedging effect, a 3-parameter packing model has been developed. The 3-parameter model was calibrated by fitting the theoretical predictions with the measured results of the comprehensive study conducted herein. After calibration, the theoretical predictions agree very well with the measured results, with the prediction error generally within 1.43%. Further, some of the particle packing models were evaluated by comparing with published test results. The particle packing models so evaluated include the 2-parameter model (with the loosening and wall effects incorporated), the compressible model (with the loosening, wall and compaction effects incorporated) and the 3-parameter model (with the loosening, wall and wedging effects incorporated). It was found that the accuracy of the models varies with both the size ratio and volumetric fractions of the binary mix. In general, when the size ratio is larger than 0.65, all the packing models are sufficiently accurate. However, when the size ratio is smaller than 0.65, the 2-parameter model and the compressible model would either over- or under-estimate the packing density with the prediction errors generally larger at around the volumetric fractions giving maximum packing density. On the other hand, within the whole range of size ratio from 0.02 to 0.74 covered by the test results used for evaluation of the packing models, the packing density prediction by the 3-parameter model are accurate to within an absolute error of 0.020. Overall, the better performance of the 3-parameter model may be attributed to the incorporation of the wedging effect. With the wedging effect incorporated, the 3-parameter model is the most accurate and generally applicable to the whole range of size ratio from 0 to 1. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

No description available.

Thesis (Ph.D.)--Syracuse University, 2008. / "Publication number: AAT 3345024."

Thesis (M.S.)--University of Akron, Dept. of Mathematics, 2009. / "May, 2009." Title from electronic thesis title page (viewed 7/28/2009) Advisor, Dmitry Golovaty; Faculty Readers, Gerald Young, Patrick Wilber; Department Chair, Joseph Wilder; Dean of the College, Chand Midha; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Digitized by Kansas Correctional Industries

Dong Lei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 75-80). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction to dielectrophoresis --- p.1 / Chapter 1.2 --- Overview of recent works on dielectrophoresis --- p.2 / Chapter 1.3 --- Objectives of the thesis --- p.3 / Chapter 2 --- Dielectrophoresis of homogeneous dielectric spheres in suspen- sions --- p.6 / Chapter 2.1 --- Multiple image method for a pair of homogeneous colloidal par- ticles --- p.7 / Chapter 2.1.1 --- Derivation of the dipole factor --- p.8 / Chapter 2.1.2 --- DEP force for a pair of dielectric spheres --- p.10 / Chapter 2.1.3 --- Multiple image method for the dipole factor of a pair of approaching dielectric spheres --- p.13 / Chapter 2.2 --- Spectral representation and the DEP dispersion spectrum --- p.14 / Chapter 2.3 --- Numerical results --- p.17 / Chapter 2.4 --- Discussion and Conclusion --- p.21 / Chapter 3 --- Electro-orientation of colloidal suspensions --- p.24 / Chapter 3.1 --- Turn-over frequency in electro-orientation --- p.25 / Chapter 3.2 --- Force between a pair of polarized spheres --- p.30 / Chapter 3.3 --- Many-body effects --- p.34 / Chapter 3.4 --- Multipole force due to an intrinsic dispersion --- p.36 / Chapter 3.5 --- Discussion and Conclusion --- p.40 / Chapter 4 --- Exact solutions for graded dielectric spheres in suspensions --- p.42 / Chapter 4.1 --- Exact solutions for the dipole factor --- p.43 / Chapter 4.1.1 --- Exact solution for a power-law profile --- p.46 / Chapter 4.1.2 --- Exact solution for a linear profile with a small slope --- p.48 / Chapter 4.1.3 --- Exact solution of dipole factor for coated microparticles . --- p.50 / Chapter 4.2 --- Comparison between the first-principle approach and other methods --- p.54 / Chapter 4.2.1 --- Comparison with the differential effective dipole approx- imation --- p.55 / Chapter 4.2.2 --- Comparison with the variational approach --- p.56 / Chapter 4.3 --- Effective dielectric constant in the cellular model --- p.59 / Chapter 4.4 --- Discussion and Conclusion --- p.62 / Chapter 5 --- Dielectrophoresis of graded dielectric spheres in suspensions --- p.64 / Chapter 5.1 --- Dielectric response of an isolated graded sphere --- p.66 / Chapter 5.2 --- Dielectric response of a pair of touching graded spheres --- p.69 / Chapter 5.3 --- Discussion and Conclusion --- p.71 / Chapter 6 --- Conclusion --- p.73 / Bibliography --- p.75

This experiment is concerned with sampling submicrometer particles in near sonic and supersonic flows. The study employed a high volume condensation aerosol generator to produce stearic acid particles having a geometric mean diameter of 0.8 μm and a geometric standard deviation of 1.28. The aerosol was diluted with dry air and accelerated to Mach 0.6, 0.8, 1.26, or 1.47 through a flow nozzle. Aerosol mass concentrations were determined using a small bore probe in the jet and by a large bore probe sampling isokinetically upstream of the jet nozzle. The results of both samples were compared to compute the sampling error associated with the high speed jet sample. The mass of stearic acid collected on polycarbonate membrane filters was determined by gravimetric and chromatographic methods. Studies at Mach 0.8 with four sampling probes having inlet wall to bore area ratios ranging from 3.8 to 0.28 demonstrated that probe wall thickness effects are not significant when the sample is extracted isokinetically. Subisokinetic experiments using a knife edged probe showed relative errors of 124 ± 12% when sampling at 20% of the isokinetic condition. The subisokinetic results are compared favorably with the extended empirical results of other authors. For the supersonic cases it is shown that the subsonic velocity downstream of the sampling probe bow shock can be used in estimating the sampling error. / Graduation date: 1991

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 54-56).

published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy