GENERATION OF MULTICOMPONENT POLYMER BLEND MICROPARTICLES USING DROPLET EVAPORATION TECHNIQUE AND MODELING EVAPORATION OF BINARY DROPLET CONTAINING NON-VOLATILE SOLUTE

Recently, considerable attention has been focused on the generation of nano- and micrometer scale multicomponent polymer particles with specifically tailored mechanical, electrical and optical properties. As only a few polymer-polymer pairs are miscible, the set of multicomponent polymer systems achievable by conventional methods, such as melt blending, is severely limited in property ranges. Therefore, researchers have been evaluating synthesis methods that can arbitrarily blend immiscible solvent pairs, thus expanding the range of properties that are practical. The generation of blended microparticles by evaporating a co-solvent from aerosol droplets containing two dissolved immiscible polymers in solution seems likely to exhibit a high degree of phase uniformity. A second important advantage of this technique is the formation of nano- and microscale particulates with very low impurities, which are not attainable through conventional solution techniques. When the timescale of solvent evaporation is lower than that of polymer diffusion and self-organization, phase separation is inhibited within the atto- to femto-liter volume of the droplet, and homogeneous blends of immiscible polymers can be produced. We have studied multicomponent polymer particles generated from highly monodisperse micrordroplets that were produced using a Vibrating Orifice Aerosol Generator (VOAG). The particles are characterized for both external and internal morphology along with homogeneity of the blends. Ultra-thin slices of polymer particles were characterized by a Scanning Electron Microscope (SEM), and the degree of uniformity was examined using an Electron Dispersive X-ray Analysis (EDAX). To further establish the homogeneity of the polymer blend microparticles, differential scanning calorimeter was used to measure the glass transition temperature of the microparticles obtained. A single glass transition temperature was obtained for these microparticles and hence the homogeneity of the blend was concluded. These results have its significance in the field of particulate encapsulation. Also, better control of the phase morphologies can be obtained by simply changing the solvent/solvents in the dilute solutions. Evaporation and drying of a binary droplet containing a solute and a solvent is a complicated phenomenon. Most of the present models do not consider convection in the droplet phase as solvent is usually water which is not very volatile. In considering highly volatile solvents the evaporation is very rapid. The surface of the droplet recedes inwards very fast and there is an inherent convective flow that is established inside the solution droplet. In this dissertation work, a model is developed that incorporates convection inside the droplet. The results obtained are compared to the size obtained from experimental results. The same model when used with an aqueous solution droplet predicted concentration profiles that are comparable to results obtained when convection was not taken into account. These results have significance for more rigorous modeling of binary and multicomponent droplet drying

Effect of materials on the urban thermal environment a CFD simulation approach

Use of high albedo materials reduces the amount of solar radiation absorbed through building envelops and urban structures and thus keeping their surfaces cooler. The cooling energy savings by using high albedo materials have been well documented. Higher surface temperatures add to increasing the ambient temperature as convection intensity is higher. Such temperature increase has significant impacts on the air conditioning energy utilization in hot climates. This study makes use of a parametric approach by varying the temperature of building facades to represent commonly used materials and hence analyzing its effect on the air temperature through a series of CFD (Computational Fluid Dynamics) simulations. A part of the existing CBD (Central Business District) area of Singapore was selected for the study. Series of CFD simulations have been carried out using the software CFX-5.6. Wind tunnel experiments were also conducted for validation. It was found that at low wind speeds, the effect of materials on the air temperature was significant and the temperature at the middle of a narrow canyon increased up to 2.52&deg;C with the fa&ccedil;ade material having lowest albedo.<br /

An Optimization of Energy Saving in Cloud Environment

Cloud computing is a technology in distributed computing which facilitates pay per model based on user demand and requirement. Cloud can be defined as a collection of virtual machines. This includes both computational and storage facility. The goal of cloud computing is to provide efficient access to remote and geographically distributed resources. Cloud Computing is developing day by day and faces many challenges; one of them is i) Load Balancing and ii) Task scheduling. Load balancing is defined as division of the amount of work that a system has to do between two or more systems so that more work gets done in the same amount of time and all users get served faster. Load balancing can be implemented with hardware, software, or a combination of both. Load balancing is mainly used for server clustering. Task Scheduling is a set of policies to control the work order to be performed by a system. It is also a technique which is used to improve the overall execution time of the job. Task Scheduling is responsible for selection of best suitable resources for task execution, by taking some parameters into consideration. A good task scheduler adapts its scheduling strategy according to the changing environment and the type of task. In this paper, the Energy Saving Load Balancing (ESLB) Algorithm and Energy Saving Task Scheduling (ESTS) algorithm was proposed. The various scheduling algorithms (FCFS, RR, PRIORITY, and SJF) are reviewed and compared. The ESLB algorithm and ESTS algorithm was tested in cloudsim toolkit and the result shows better performance