Particle characterization is a principal factor in the research and development of the product, production, and material quality control. Particle Size plays a critical role in the borderline sciences, such as biotechnology and nanotechnology. In this study, light scattering devices ( dynamic and Static) and their theory is discussed. Also, suggest theory to calculate form factor of scattering such as Rayleigh and Mi e was explained.

Most properties of nanoParticles are Size-dependent. In fact, the novel properties of nanoaprticles do not prevail until the Size has been reduced to the nanometer scale. The Particle Size and Size distribution of alumina nanoParticle, as a critical properties, have been determined by transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), surface area analysis (BET) and x-ray diffraction peak broadening analysis. The Particle Size was found to be in the range of 5-95 nm. Cumulative percentage frequency plot of the data extracted form TEM images indicates that Particle Size distribution obeys the log-normal function. The TEM images also reveal that Particles are spherical in shape and loosely agglomerated. Comparing of the XRD and TEM results shows that the Particles are single-crystal. The HRTEM images also verify that the Particles have a single-crystal nature. In comparison, there is a good correlation between the BET, XRD and TEM measurements other than PCS that is sensitive to the presence of the agglomerates.

The hydrocyclone has a very important roll in industrial separation. The consideration of its behavior is very important for design. In this investigation, behavior of water flow and Particles trajectory inside a hydrocyclone has been considered by means of numerical and experimental methods, and results have been compared together. To have a numerical simulation, a CFD software was used, and for modeling flow the RNG k-e model applied. Finally, the effect of Particle Size on hydrocyclone performance has been studied. It was found that the grade efficiency and number of Particle that exit from underflow of the hydrocyclone is increased when bigger Particles is used.A series of experiments has been carried out in a laboratory with a hydrocyclone. Comparison shows that, there is a good agreement between the CFD models and experimental result.

In this paper, flow past a single Dissipative Particle Dynamics (DPD) Particle with low Reynolds number is investigated and it is inquired that whether a single DPD Particle immersed in a fluid, has an intrinsic Size. Then a minimum length scale is determined such that the hydrodynamic behavior based on standard DPD formulation is modeled correctly. Almost all of the previous studies assume the DPD Particles as point centers of repulsion with no intrinsic Size. Hence to prescribe the Size of a simulating sphere, a structure of frozen DPD Particles is created. In this paper two effective radii, Stokes-Einstein radius and a radius based on the Stokes law, for DPD Particles are introduced. For small Reynolds numbers; it is proved that the two radii approach each other. Finally in spite of the typical simulations which assume DPD Particles as point centers of repulsion, it is concluded that each of the individual DPD Particles interact with other Particles as a sphere with non-zero radius. It results the reduction of the required number of Particles and eventuates more economical simulations. Moreover contemplating the radius of the Particles is necessary for the new Low-Dimensional model which is derived based on the DPD method.

Considering safety and environmental issues are very important in all domains of agriculture, industry and services in different countries. In the agricultural domain despite of numerous efforts to find alternative methods, millions of liters of toxic chemicals are used by chemical methods to control plant pests every year. Certainly, the most important issue in spraying is the Size of drops which is influenced by several factors including pressure, nozzle hole diameter, viscosity of the chemical solution and wind speed in the area. In this study, MLP network Feed Forward modeling was used. Input consisted of two layers including nozzle diameter (three Sizes) and spraying pressure (three pressure levels). Output of the artificial neural network determined by volume median diameter. In order to choose the best procedure, five methods including gradient descending, descending gradient with momentum, Levenberg-Marquart, conjugate gradient and Delta Bar Delta were used. Considering both minimum mean square error and coefficient of determination, the descending gradient with momentum was chosen. After training and validation of the network, MSE and coefficient of determination were 0.0176 and 0.90, respectively. In order to verify the results from neural network several tests were carried out and observed Particle diameters were compared with values obtained from neural networks by chi-square test. The difference was not significant. These results indicate that neural networks can estimate properly the Size of the droplets.

Investigation on physical characteristics of suspended sediment is an important subject in river studies. The Particle Size distribution of the suspended sediment is one of these physical properties represents important links between sources and fluvial mechanisms in the watersheds. However, limited studies have been conducted in field of suspended sediment Particle Size distribution. The present study therefore aimed to investigate the Particle Size distribution of suspended sediments in Kojour River within the period of one year. Toward this attempt, 24 suspended sediment samples were collected at intervals of some 15 days. The Particle Size distribution was determined after necessary preparations by laser scattering Particle Size of HORIBA LA-950. The results showed that the suspended sediment diameter were in the range of 0.82 to 353.55 microns during time of sampling and in different conditions. Also, the silt Particles with partial contribution of 97.68 % had the largest contribution in the suspended sediment load. In addition, the results indicated that the precipitation and sand harvesting plays an important role in increasing the coarse Particles of suspended sediment load.