Research Selections 2011

The Australian Nuclear Science and Technology Organisation (ANSTO) is the home of Australia’s nuclear science expertise. This expertise is applied to radiopharmaceutical production and biomedical research, climate change research, water resource management, materials engineering, neutron science and a range of other disciplines. ANSTO is a Federal Government agency with the mission to apply nuclear science for the benefit of all Australians. It operates Australia’s nuclear reactor, OPAL, for research and isotope production. Critical research carried out at ANSTO involves the neutron beam instruments attached to OPAL, run by ANSTO’s Bragg Institute, Australia’s leading neutron scattering research group. ANSTO operates particle accelerators to analyse the elemental composition and age of materials. ANSTO has two accelerators, ANTARES and STAR, both of which are used in ion beam analysis and accelerator mass spectrometry. Two new accelerators will be established, putting ANSTO at the forefront of this field worldwide. ANSTO is a founding partner in the national accelerator collaboration – Australian Collaboration for Accelerator Science (ACAS) – aimed at maintaining state-of-the-art facilities and a pool of accelerator experts. ANSTO is also one of the ten foundation investors in the Australian Synchrotron. As custodian of this world-class infrastructure, ANSTO attracts scientists from around the world to use the facilities. Approximately three hundred scientists use ANSTO’s neutron beam instuments each year, enabling productive collaborations, and keeping Australia at the forefront of scientific discovery. ANSTO researchers are engaged in international research through reciprocal arrangements with many organisations. Agreements for collaborations have recently been signed with the French Atomic Energy Commission, the Korean Atomic Energy Research Institute and CERN, home of the Large Hadron Collider in Switzerland

Proceedings of the Thirteenth International Conference on Time-Resolved Vibrational Spectroscopy

The thirteenth meeting in a long-standing series of “Time-Resolved Vibrational Spectroscopy” (TRVS) conferences was held May 19th to 25th at the Kardinal Döpfner Haus in Freising, Germany, organized by the two Munich Universities - Ludwig-Maximilians-Universität and Technische Universität München. This international conference continues the illustrious tradition of the original in 1982, which took place in Lake Placid, NY. The series of meetings was initiated by leading, world-renowned experts in the field of ultrafast laser spectroscopy, and is still guided by its founder, Prof. George Atkinson (University of Arizona and Science and Technology Advisor to the Secretary of State). In its current format, the conference contributes to traditional areas of time resolved vibrational spectroscopies including infrared, Raman and related laser methods. It combines them with the most recent developments to gain new information for research and novel technical applications. The scientific program addressed basic science, applied research and advancing novel commercial applications. The thirteenth conference on Time Resolved Vibrational Spectroscopy promoted science in the areas of physics, chemistry and biology with a strong focus on biochemistry and material science. Vibrational spectra are molecule- and bond-specific. Thus, time-resolved vibrational studies provide detailed structural and kinetic information about primary dynamical processes on the picometer length scale. From this perspective, the goal of achieving a complete understanding of complex chemical and physical processes on the molecular level is well pursued by the recent progress in experimental and theoretical vibrational studies. These proceedings collect research papers presented at the TRVS XIII in Freising, German

Aerospace Medicine and Biology - A continuing bibliography with indexes

Annotated bibliography and indexes on Aerospace Medicine and Biology - Dec. 196

Microfluidic synthesis of colloidal nanomaterials

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.Includes bibliographical references.This thesis focuses on microfluidics based approaches for synthesis and surface-engineering of colloidal particles. Bottom-up assembly through colloidal nucleation and growth is a popular route to the controlled synthesis of nanomaterials. Standard bench-scale synthetic chemistry techniques often involve non-uniform spatial and temporal distributions of concentration and temperature, and are not readily scalable. Photolithography-based microfabrication enables the application of classical techniques of chemical reaction engineering to design chemical reactors that cannot be realized easily at the macroscale, and that closely approach theoretical 'idealized' reactor configurations. In addition, the microfluidic format allows precisely controlled reaction conditions such as rapid mixing, and concentration and temperature uniformity. The goal of this thesis was to design microfluidic reactors for synthesis of core-shell colloidal particles with tunable sizes. Microscale segmented gas-liquid flows overcome the large axial dispersion effects associated with single-phase laminar flows. Microchannel devices that yielded uniform, stable gas-liquid segmented flows over three orders of magnitude in flow velocity were first developed.(cont.) Extensive experimental studies of the transport, dynamics and stability of such flows were then conducted with pulsed-laser fluorescent microscopy, optical stereomicroscopy and micro particle image velocimetry (-PIV). Flow segmentation not only reduces axial dispersion, but also allows rapid micromixing of miscible liquids through internal recirculations in the liquid phase. This added functionality is especially useful in syntheses involving colloidal particles that, due to inherently low diffusivity, cannot be rapidly mixed by laminar diffusive techniques. Continuous segmented flow reactors were then developed for the synthesis of colloidal silica and titania particles by sol-gel chemistry. Particle sizes could be tuned by varying the rates of flow of reactants, or by varying the chip temperature. Particle size distributions comparable to or narrower than the corresponding stirred-flask synthesis, with little agglomeration or shape distortion were obtained. Coating of colloidal particles with one or more layers of different materials is used to modify their optical, chemical or surface properties. Core-shell particles are often prepared by controlled precipitation of inorganic precursors onto core particles.(cont.) Synthesis of such structures requires precise control over process parameters to prevent precipitation of secondary particles of shell material and agglomeration of primary particles. Particles coated with titania are exceptionally difficult to synthesize due to the high reactivity of the titania precursors, which makes controlled precipitation difficult. A novel continuous flow microfluidic reactor with sequential multi-point precursor addition was developed for colloidal overcoating processes. Silica particles were coated with uniform titania layers of tunable thickness by the controlled hydrolysis of titanium ethoxide, with no secondary particle formation or agglomeration. An integrated reactor for continuous silica synthesis and in-situ series overcoating with titania was then developed using a two-level stacked reactor fabrication process. Finally, multi-step nanomaterials synthesis and surface coating with incompatible chemistries requires the development of microfluidic 'unit operations' equivalent to particle filtration. In this context, rapid, continuous microfluidic particle separation was demonstrated using transverse free-flow electrophoresis.by Saif A. Khan.Ph.D

Jet Mixing Enhancement by High Amplitude Pulse Fluidic Actuation

Turbulent mixing enhancement has received a great deal of attention in the fluid mechanics community in the last few decades. Generally speaking, mixing enhancement involves the increased dispersion of the fluid that makes up a flow. The current work focuses on mixing enhancement of an axisymmetric jet via high amplitude fluidic pulses applied at the nozzle exit with high aspect ratio actuator nozzles. The work consists of small scale clean jet experiments, small scale micro-turbine engine experiments, and full scale laboratory simulated core exhaust experiments using actuators designed to fit within the engine nacelle of a full scale aircraft. The small scale clean jet experiments show that mixing enhancement compared to the unforced case is likely due to a combination of mechanisms. The first mechanism is the growth of shear layer instabilities, similar to that which occurs with an acoustically excited jet except that, in this case, the forcing is highly nonlinear. The result of the instability is a frequency bucket with an optimal forcing frequency. The second mechanism is the generation of counter rotating vortex pairs similar to those generated by mechanical tabs. The penetration depth determines the extent to which this mechanism acts. The importance of this mechanism is therefore a function of the pulsing amplitude. The key mixing parameters were found to be the actuator to jet momentum ratio (amplitude) and the pulsing frequency, where the optimal frequency depends on the amplitude. The importance of phase, offset, duty cycle, and geometric configuration were also explored. The experiments on the jet engine and full scale simulated core nozzle demonstrated that pulse fluidic mixing enhancement was effective on realistic flows. The same parameters that were important for the cleaner small scale experiments were found to be important for the more realistic cases as well. This suggests that the same mixing mechanisms are at work. Additional work was done to optimize, in real time, mixing on the small jet engine using an evolution strategy.Ph.D.Committee Chair: David Parekh; Committee Member: Ari Glezer; Committee Member: Jeff Jagoda; Committee Member: Richard Gaeta; Committee Member: Samuel Shelto

The quantitative analysis of transonic flows by holographic interferometry

This thesis explores the feasibility of routine transonic flow analysis by holographic interferometry. Holography is potentially an important quantitative flow diagnostic, because whole-field data is acquired non-intrusively without the use of particle seeding. Holographic recording geometries are assessed and an image plane specular illumination configuration is shown to reduce speckle noise and maximise the depth-of-field of the reconstructed images. Initially, a NACA 0012 aerofoil is wind tunnel tested to investigate the analysis of two-dimensional flows. A method is developed for extracting whole-field density data from the reconstructed interferograms. Fringe analysis errors axe quantified using a combination of experimental and computer generated imagery. The results are compared quantitatively with a laminar boundary layer Navier-Stokes computational fluid dynamics (CFD) prediction. Agreement of the data is excellent, except in the separated wake where the experimental boundary layer has undergone turbulent transition. A second wind tunnel test, on a cone-cylinder model, demonstrates the feasibility of recording multi-directional interferometric projections using holographic optical elements (HOE’s). The prototype system is highly compact and combines the versatility of diffractive elements with the efficiency of refractive components. The processed interferograms are compared to an integrated Euler CFD prediction and it is shown that the experimental shock cone is elliptical due to flow confinement. Tomographic reconstruction algorithms are reviewed for analysing density projections of a three-dimensional flow. Algebraic reconstruction methods are studied in greater detail, because they produce accurate results when the data is ill-posed. The performance of these algorithms is assessed using CFD input data and it is shown that a reconstruction accuracy of approximately 1% may be obtained when sixteen projections are recorded over a viewing angle of ±58°. The effect of noise on the data is also quantified and methods are suggested for visualising and reconstructing obstructed flow regions

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

NASA/ASEE Summer Faculty Fellowship Program

This document is a collection of technical reports on research conducted by the participants in the 1996 NASA/ASEE Summer Faculty Fellowship Program at the Kennedy Space Center (KSC). This was the twelfth year that a NASA/ASEE program has been conducted at KSC. The 1996 program was administered by the University of Central Florida in cooperation with KSC. The program was operated under the auspices of the American Society for Engineering Education (ASEE) with sponsorship and funding from the Office of Educational Affairs, NASA Headquarters, Washington, DC and KSC. The KSC Program was one of nine such Aeronautics and Space Research Program funded by NASA in 1996. The NASA/ASEE Program is intended to be a two-year program to allow in-depth research by the University faculty member. The editors of this document were responsible for selecting appropriately qualified faculty to address some of the many problems of current interest to NASA/KSC