Structure and Mobility of Lactose in Lactose/Sodium Montmorillonite Nanocomposites

This study aims at investigating the molecular level organization and molecular mobility in montmorillonite nanocomposites with the uncharged organic low-molecular-weight compound lactose commonly used in pharmaceutical drug delivery, food technology, and flavoring. Nanocomposites were prepared under slow and fast drying conditions, attained by drying at ambient conditions and by spray-drying, respectively. A detailed structural investigation was performed with modulated differential scanning calorimetry, powder X-ray diffraction, solid-state nuclear magnetic resonance, scanning electron microscopy, microcalorimetry, and molecular dynamic simulations. The lactose was intercalated in the sodium montmorillonite interlayer space regardless of the clay content, drying rate, or humidity exposure. Although, the spray-drying resulted in higher proportion of intercalated lactose compared with the drying under ambient conditions, non-intercalated lactose was present at 20 wt% lactose content. This indicates limitations in maximum load capacity of nonionic organic substances into the montmorillonite interlayer space. Furthermore, a fraction of the intercalated lactose in the co-spray-dried nanocomposites diffused out from the clay interlayer space upon humidity exposure. Also, the lactose in the nanocomposites demonstrated higher molecular mobility than that of neat amorphous lactose. This study provides a foundation for understanding functional properties of nanocomposites, such as loading capacity and physical stability

A NUMERICAL STUDY OF A NEW SPRAY APPLICATOR

This study focuses on the design and development of a new spray applicator design utilizing effects of imposed pressure oscillations in conjunction with cavitation collapse energy to create distribution of fine droplets. An oscillating horn placed inside the nozzle performing high frequency oscillations is envisioned to provide the necessary pressure perturbations on the exiting liquid jet, while the nozzle geometry design in configured to amplify cavitation process. Initially, a two-zone approach modeling the nozzle interior and exterior in a separate fashion and later, a coupled strategy is proposed. Parametric studies describing the effect of horn stroke length, frequency, its position inside the nozzle in combination with different nozzle designs and liquid flow rates are explored to identify their contribution in obtaining desired cavitation characteristics. In this regard, incorporation of a backward facing step profile within the nozzle shows strong capability of generating the required cavitation and flow field distribution at the nozzle exit. The velocity modulations occuring at the nozzle exit due to oscillating horn structure result in a wide gamut of liquid structures specific to the imposed oscillation frequency and modulation amplitude. The disintegration characteristics of these modulated liquid jets are studied using a Volume-of-Fluid (VOF) interface capturing approach based on finite volume methodology employing an interface compression scheme. VOF methods are validated against experimental results and then subsequently used to study scaling parameters governing the modulated liquid jets. To perform coupled interior-exterior nozzle computations with cavitation, two new cavitation models are presented: First, a model based on Homogeneous Equilibrium assumptions for tracking cavitation events in a compressible framework is presented. Owing to its inability to simulate incompressible cavitating flows, a new cavitation event tracking model based on a Cavitation-Induced-Momentum-Defect (CIMD) correction approach is formulated utilizing a scalar transport model for vapor volume fraction with relevant transport, diffusion and source terms. Validations of both the models against experimental observations are detailed. Coupled internal-external liquid flow computations from the proposed atomizer design using a VOF-CIMD strategy shows strong potential for rapid drop formation in the presence of cavitation effects. A prototype model of a new spray applicator design is presented

Měření vlivu kapek pro optický bezvlaknový spoj a matematické modelování vícefázového proudění

Free space optics will emerge alongside major communications technologies as an important player in the field of wireless communications. This technology, like other technologies, has to face the challenges caused by unstable and unfavorable atmospheric conditions that determine the resulting quality of the transmitted signal. The paper is intended to determine the extent of a deterioration of the transmitted signal during rainfall. The precipitation is simulated in laboratory conditions, and the resulting knowledge of the droplet formation is transferred to a mathematical model that helps simulate multiphase flow under given conditions.Optické bezvláknové spoje se v budoucnosti vyskytnou po boku majoritních komunikačních technologií jako důležitý hráč na poli bezdrátových komunikací. Tato technologie, stejně jako jiné technologie, musí čelit výzvám pramenícím z nestálých a nepříznivých atmosférických podmínek, které rozhodují o výsledné kvalitě přenášeného signálu. Tato práce má za úkol zjistit míru zhoršení přenášeného signálu během dešťových srážek. Srážkový úhrn je simulován v laboratorních podmínkách a výsledné poznatky o tvorbě dešťových kapek jsou přeneseny do matematického modelu, který napomáhá simulování vícefázového proudění v daných podmínkách.440 - Katedra telekomunikační technikyvýborn

Spray Characterization and Herbicide Efficacy as Influenced by Pulse-Width Modulation Sprayers

Pesticide applications are a heavily scrutinized facet of today’s agricultural industry, and a concerted effort to optimize each application needs to be implemented. More precise and efficient pesticide applications are necessary to meet regulatory demands and increase economic efficiency through reduced pesticide inputs. Current pesticide application methods using precision technologies, including pulse-width modulation (PWM) sprayers, can assist with these goals. However, vast advancements in pesticide formulations, adjuvants, and nozzles, as well as the increasing popularity of PWM systems, have only increased the need for applied PWM and weed science research. Additionally, efforts have been placed on increasing spray droplet size to reduce particle drift, but this practice has led to reduced herbicide efficacy. Therefore, identifying an optimum herbicide droplet size which can reduce particle drift while simultaneously maintaining efficacy is a necessity. The objectives of this research were to: (1) identify the influence of application parameters on droplet size, droplet exit velocity, nozzle tip pressure, and spray pattern uniformity from a PWM sprayer, (2) create best use PWM recommendations to optimize pesticide applications from these sprayers, (3) investigate the effect of spray droplet size and carrier volume on the efficacy of multiple herbicide solutions, (4) establish novel weed management recommendations based on an optimum droplet size, and (5) determine the plausibility of using PWM sprayers in site-specific weed management strategies. The results of this research have led to more precise PWM sprayer operation through clear and concise best use recommendations. The capability of PWM sprayers to make precise and uniform applications can assist with the reduction of spray particle drift and increase the overall application effectiveness. Additionally, site-specific weed management strategies were effectively established and optimum herbicide droplet sizes were estimated across a wide range of geographies and weed species. Although, convoluted interactions were identified between droplet size, carrier volume, and other application parameters in regards to their effect on herbicide efficacy. As a result of this research, applicators can more effectively utilize PWM sprayers, reduce herbicide inputs, mitigate spray particle drift, and reduce the selection pressure for the evolution of herbicide-resistant weeds. Advisor: Greg R. Kruge

Small business innovation research. Abstracts of completed 1987 phase 1 projects

Non-proprietary summaries of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA in the 1987 program year are given. Work in the areas of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robotics, computer sciences, information systems, spacecraft systems, spacecraft power supplies, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

Metallic nanoparticle ink formulation development and optimization for electrohydrodynamic ink-jet printing

Electrohydrodynamic (EHD) ink-jet printing has been actively researched as a means of refining ink-jet printing. Currently, most of the research on this topic has centralized on the development of the printing process and optimization, while few studies have focused on the relationships between printing materials properties and printed patterns performance. In this study, silver and tungsten-based particle-solvent dispersed inks were formulated capable of EHD printing. Several formulations were made to explore key variances in their performance. More generally, a methodology was developed to characterized and evaluate ink printability using materials properties. It identified a critical relationship between the formulation and fluid properties, which affects the printing results and functional performance. Also, particle size was studied and it was shown that it can drastically impact droplet image behaviors. In order to capture and analyze these phenomena, machine vision was utilized, assisting capture high-speed images to characterize droplet shape and timely response. In the silver-based ink formulation study, our data reveals that under identical printing conditions, the size of the printed features is a function of ink fluid viscosity, surface tension, and dielectric constant. Within the same formulation, the size of the printed features is a function of amplitude, frequency, and duty ratio of the alternating current (AC) square wave voltage signal. In our tungsten ink study, the droplet impact behaviors on glass substrates, including impact reaction time, droplet height, diameter, and dynamic contact angle, are functions of particle size of tungsten nanoparticle used in the ink formulation. With the discovery of relationships at hand, optimal formulations were proposed for inks used in the EHD printing regarding printing resolution and stabilization. The x-ray shielding efficiency was also evaluated on the differences between bulk tungsten and nanoparticle ink multilayer printed tungsten. Data suggested that with the increase of the numbers of layers printed, the shielding efficiency increases indicating an improved, denser nanoparticle packing condition. Finally, future research directions were proposed, including further improving printing resolution, improved nanoparticle packing density and 3D printability

Generation of a monodispersed aerosol

The identity and laboratory test methods for the generation of a monodispersed aerosol are reported on, and are subjected to the following constraints and parameters; (1) size distribution; (2) specific gravity; (3) scattering properties; (4) costs; (5) production. The procedure called for the collection of information from the literature, commercial available products, and experts working in the field. The following topics were investigated: (1) aerosols; (2) air pollution -- analysis; (3) atomizers; (4) dispersion; (5) particles -- optics, size analysis; (6) smoke -- generators, density measurements; (7) sprays; (8) wind tunnels -- visualization

Investigation of the Effects of Oxidizer Temperature on the Stability of a Gas-Centered Swirl Coaxial Injector

Rocket engines achieve extraordinary high energy densities within the chamber in the form of high pressure turbulent combustion. Successful design of these engines requires sustained, stable operation of a combustor exposed to extreme thermal loads. Slight deviations in operating conditions can then incur consequences ranging from reduced performance up to catastrophic failure in the face of excess heat loading. Sustained periodic oscillations, termed combustion instabilities, are often encountered during development, as fluctuations produced by combustion noise couple with heat release modes by way of modulation of the feed system, injector hydrodynamics, chemical kinetics, and mixing and atomization process. Successful development of reliable, high performance rocket engines can be achieved either through a thorough understanding of both injector and combustor dynamics to mitigate these instabilities or through the laborious design/test iteration process. This document describes a two-fold work by the author. The first objective considers the acquisition of high-fidelity data sets of a single gas-centered swirl coaxial injector for use in the validation of computational models. Secondly, the stability of this injector was studied at two oxidizer inlet temperatures. Combustion stability was assessed through variation of the combustor geometry. Previous research shows that varying this geometry can either drive or dampen pressure oscillations. Testing was conducted on an experimental test bed equipped with modular sections to accommodate changing oxidizer post and chamber lengths. A single gas-centered swirl coaxial injector was used, with operating parameters based on the RD-180 injector element, such as equivalence and momentum flux ratios. Two oxidizer inlet temperatures were chosen. The first was oxygen combusted with gaseous hydrogen at lean conditions in a preburner to produce hot oxidizer near 700 K. The second was pure oxygen delivered at room temperature. Results from the test campaign revealed the system to be classically stable across all configurations and inlet conditions tested, with pressure perturbations less than 10% of the mean chamber pressure. Discriminating behavior was observed between the two oxidizer inlet temperatures. At elevated temperatures, peak-to-peak pressure oscillations observed throughout the system were small at less than 4% of the mean chamber pressure. There was no observed dependency of the amplitude on geometry. At ambient temperatures, the pressure oscillations ranged from 4% up to 7%. The increase in amplitudes were similar to that of the acoustic refection coefficient between the oxidizer and chamber gas, based on their acoustic specific impedance. An increase in the acoustic transmission coefficient was also observed, going from hot to ambient oxidizer. The increase in these two values would not necessarily lead to enhanced coupling between the chamber and resonance behavior in the post, but is expected to amplify pressure oscillations. At the ambient condition, clear variation in amplitudes were generated through manipulation of the geometry. The general trend matched previous experiments but was not followed by all tested configurations. It was determined that a methodology solely based on the effective resonator wavelength was not sufficient to predict the amplitude of pressure oscillations. Instead, a better predictor of amplitude was found based on the alignment of the system with postulated vortex generation from the injector face and impingement on the chamber walls. The time between local pressure oscillations and final impingement of the resulting vortices fell between one and two cycles of the fundamental longitudinal chamber mode, increasing linearly in strength as phase lag increased