Control Theory: On the Way to New Application Fields

Control theory is an interdisciplinary field that is located at the crossroads of pure and applied mathematics with systems engineering and the sciences. Recently, deep interactions are emerging with new application areas, such as systems biology, quantum control and information technology. In order to address the new challenges posed by the new application disciplines, a special focus of this workshop has been on the interaction between control theory and mathematical systems biology. To complement these more biology oriented focus, a series of lectures in this workshop was devoted to the control of networks of systems, fundamentals of nonlinear control systems, model reduction and identification, algorithmic aspects in control, as well as open problems in control

MODELING OF AN AIR-BASED DENSITY SEPARATOR

There is a lack of fundamental studies by means of state of the art numerical and scale modeling techniques scrutinizing the theoretical and technical aspect of air table separators as well as means to comprehend and improve the efficiency of the process. The dissertation details the development of a workable empirical model, a numerical model and a scale model to demonstrate the use of a laboratory air table unit. The modern air-based density separator achieves effective density-based separation for particle sizes greater than 6 mm. Parametric studies with the laboratory scale unit using low rank coal have demonstrated the applicability with regards to finer size fractions of the range 6 mm to 1 mm. The statistically significant empirical models showed that all the four parameters, i.e, blower and table frequency, longitudinal and transverse angle were significant in determining the separation performance. Furthermore, the tests show that an increase in the transverse angle increased the flow rate of solids to the product end and the introduction of feed results in the dampening of airflow at the feed end. The higher table frequency and feed rate had a detrimental effect on the product yield due to low residence time of particle settlement. The research further evaluated fine particle upgrading using various modeling techniques. The numerical model was evaluated using K-Epsilon and RSM turbulence formulations and validated using experimental dataset. The results prove that the effect of fine coal vortices forming around the riffles act as a transport mechanism for higher density particle movement across the table deck resulting in 43% displacement of the midlings and 29% displacement of the heavies to the product side. The velocity and vector plots show high local variance of air speeds and pressure near the feed end and an increase in feed rate results in a drop in deshaling capability of the table. The table was further evaluated using modern scale-modeling concepts and the scaling laws indicated that the vibration velocity has an integral effect on the separation performance. The difference between the full-scale model and the scaled prototype was 3.83% thus validating the scaling laws

Microfabrication Technology for Isolated Silicon Sidewall Electrodes and Heaters

This paper presents a novel microfabricationtechnology for highly doped silicon sidewall electrodesparallel to – and isolated from – the microchannel. Thesidewall electrodes can be utilised for both electricaland thermal actuation of sensor systems. Thetechnology is scalable to a wide range of channelgeometries, simplifies the release etch, and allows forfurther integration with other Surface ChannelTechnology-based systems. Furthermore, thefabrication technology is demonstrated through thefabrication of a relative permittivity sensor. The sensormeasures relative permittivity values ranging from 1 to80, within 3% accuracy of full scale, including waterand water-containing mixtures

Velocity-independent thermal conductivity and volumetric heat capacity measurement of binary gas mixtures

In this paper, we present a single hot wire suspended over a V-groove cavity that is used to measure the thermal conductivity ($k$) and volumetric heat capacity ($\rho c_p$) for both pure gases and binary gas mixtures through DC and AC excitation, respectively. The working principle and measurement results are discussed

Research and Technology 1996

This report selectively summarizes the NASA Lewis Research Center's research and technology accomplishments for fiscal year 1996. It comprises 116 short articles submitted by the staff scientists and engineers. The report is organized into six major sections: Aeronautics, Aerospace Technology, Space Flight Systems, Engineering & Computational Support, Lewis Research Academy, and Technology Transfer. The diversity of topics attests to the breadth of research and technology being pursued and to the skill mix of the staff that makes it possible. This report is not intended to be a comprehensive summary of all research and technology work done over the past fiscal year

Data-Driven Methods to Build Robust Legged Robots

For robots to ever achieve signicant autonomy, they need to be able to mitigate performance loss due to uncertainty, typically from a novel environment or morphological variation of their bodies. Legged robots, with their complex dynamics, are particularly challenging to control with principled theory. Hybrid events, uncertainty, and high dimension are all confounding factors for direct analysis of models. On the other hand, direct data-driven methods have proven to be equally dicult to employ. The high dimension and mechanical complexity of legged robots have proven challenging for hardware-in-the-loop strategies to exploit without signicant eort by human operators. We advocate that we can exploit both perspectives by capitalizing on qualitative features of mathematical models applicable to legged robots, and use that knowledge to strongly inform data-driven methods. We show that the existence of these simple structures can greatly facilitate robust design of legged robots from a data-driven perspective. We begin by demonstrating that the factorial complexity of hybrid models can be elegantly resolved with computationally tractable algorithms, and establish that a novel form of distributed control is predicted. We then continue by demonstrating that a relaxed version of the famous templates and anchors hypothesis can be used to encode performance objectives in a highly redundant way, allowing robots that have suffered damage to autonomously compensate. We conclude with a deadbeat stabilization result that is quite general, and can be determined without equations of motion.PHDElectrical Engineering: SystemsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/155053/1/gcouncil_1.pd

Experimental study of cellular instabilities in non-premixed flames

A systematic experimental study was performed to elucidate the conditions for which cellular patterns of diluted hydrogen diffusion flames near extinction were observed. The formation of cellular instabilities was studied for several burners: jet burners (axisymmetric jet and two-dimensional jet) and a novel one-dimensional burner. The fuel and oxidizer Lewis numbers and the initial mixture strength (fuel-to-oxygen concentration ratio normalized by the stoichiometric value) were identified as the key governing parameters. The formation of cellular flames occurs for low reactant Lewis numbers (less than one) and near the extinction limit. For the jet burners, the parameter space for cellularity was found to decrease with either decreasing initial mixture strength, either increasing the fuel jet velocity. For a given fuel mixture, the wavelength associated with the cellular instabilities was found to decrease with either decreasing oxygen concentration, or increasing the fuel jet velocity. To study the supression of hydrodynamic effects on the cellular instabilities, a unique burner was constructed to experimentally realize a onedimensional unstrained planar non-premixed flame, previously only considered in idealized theoretical models. The results shos that when the oxidizer diffuses against the bulk flow the propensity of cellular instabilities increases with decreasing the initial mixture strength which is in agreement with the theoretical predicitions for this type of burner as well as experimental results for jet diffusion flames

The 1994 Silver Anniversary of APOLLO 11: From the Moon to the Stars

This report summarizes the technology transfer, advanced studies, and research and technology efforts in progress at Marshall Space Flight Center (MSFC) in 1994