Energy cycle and bound of Qi chaotic system

© 2017 The Qi chaotic system is transformed into a Kolmogorov-type system, thereby facilitating the analysis of energy exchange in its different forms. Regarding four forms of energy, the vector field of this chaotic system is decomposed into four forms of torque: inertial, internal, dissipative, and external. The rate of change of the Casimir function is equal to the exchange power between the dissipative energy and the supplied energy. The exchange power governs the orbital behavior and the cycling of energy. With the rate of change of Casimir function, a general bound and least upper bound of the Qi chaotic attractor are proposed. A detailed analysis with illustrations is conducted to uncover insights, in particular, cycling among the different types of energy for this chaotic attractor and key factors producing the different types of dynamic modes

An Investigation into Delta Wing Vortex Generators as a Means of Increasing Algae Biofuel Raceway Vertical Mixing Including an Analysis of the Resulting Turbulence Characteristics

Algae-derived biodiesel is currently under investigation as a suitable alternative to traditional fossil-fuels. Though it possesses many favorable characteristics, algae remains prohibitively expensive to mass produce and distribute. The most economical means of growing algae are large-scale open pond raceways. These, however, suffer from low culture densities; this fact impacts the cost directly through diminished productivity, as well as indirectly by raising costs due to the necessity of dewatering low culture density raceway effluent. Algae, as a photosynthetic organism, achieves higher culture densities when sufficient light is provided. In open ponds this can be accomplished by frequently cycling algae to the raceway surface. The current work examined delta wing vortex generators as a means of instigating this cycling motion. In particular the impact of spacing and angle of attack was analyzed. These vortex generators were found to significantly increase vertical mixing when placed in a series, developing precisely the motion desired. Their impact on power requirements was also examined. Specifically it was shown that increases in spacing and decreases in angle of attack result in lower power consumption. It was demonstrated that the most efficient mixing generation is achieved by larger spacings and smaller angles of attack. The impact that these devices had on raceway turbulence as measured by dissipation rate was also investigated and compared to published values for algae growth. Raceways were found to be significantly more turbulent than standard algae environments, and adding delta wings increased these levels further

Investigation of Nonlinear Aeroelasticity

The investigation of nonlinear aeroelastic phenomena is becoming increasingly important to the aerospace community. The existence of structural and aerodynamic nonlinearities in aircraft has always been acknowledged but, it is only mainly with the advent of modern digital computers that their investigation has become possible. Additionally, aircraft control systems are becoming increasingly nonlinear with the introduction of Active Control Technology. The effects of these nonlinearities on the dynamic response of aircraft have created the need for further research into the modelling, identification and prediction nonlinear aeroelastic systems. This thesis deals with four aspects of nonlinear aeroelasticity. Firstly, the effect of the common industrial approach to nonlinearity, i.e. that of linearisation, is investigated. Six flutter prediction methods for linear aircraft are tested and compared on linear and nonlinear mathematical models of aeroelastic systems. The performances of the methods on linear systems are evaluated and compared. Subsequently, their predictions predictions when applied to nonlinear systems are assessed. Secondly, the dynamic response of nonlinear aircraft is investigated by means of the Harmonic Balance method and the direct integration of the nonlinear mathematical model. Emphasis is given to the explanation of the appearance of Limit Cycle Oscillations as Hopf bifurcations and on the control and suppression of these oscillations by means of a feedback control system. The chaotic vibration of nonlinear aeroelastic systems is also investigated by means of Poincare diagrams and Lyapunoff exponents. Thirdly, the identification of nonlinear aeroelastic systems is considered. Identification of aeroelastic systems is important since, especially in the case of structural nonlinearities, it is often not known whether an aircraft is linear or not and what nonlinearities it may contain until it is tested, either on the ground (Ground Vibration Testing) or in the air (Flight Flutter Testing). An existing nonlinear system identification method is compared to an approach developed during the course of the present project. The two techniques are applied to a nonlinear mathematical aeroelastic system and to a set of nonlinear input-output data obtained from an experimental system. Both methods were found to be able to deal with both systems with varying degrees of success. Finally, the gust response of nonlinear aircraft is investigated with particular emphasis on the calculation of gust design loads. Turbulent gust clearance is a very important part of any airworthiness testing procedure. Until recently, the linear assumption was considered adequate by the requirements however, there is a current shift towards setting new requirements that take into account nonlinear phenomena. Eight gust load prediction methods for nonlinear aircraft(both stochastic and deterministic) are applied to a simple and a more complex nonlinear mathematical aircraft model. The performance of the methods is assessed with respect to both accuracy and computational efficiency

Holistic biomimicry: a biologically inspired approach to environmentally benign engineering

Humanity's activities increasingly threaten Earth's richness of life, of which mankind is a part. As part of the response, the environmentally conscious attempt to engineer products, processes and systems that interact harmoniously with the living world. Current environmental design guidance draws upon a wealth of experiences with the products of engineering that damaged humanity's environment. Efforts to create such guidelines inductively attempt to tease right action from examination of past mistakes. Unfortunately, avoidance of past errors cannot guarantee environmentally sustainable designs in the future. One needs to examine and understand an example of an environmentally sustainable, complex, multi-scale system to engineer designs with similar characteristics. This dissertation benchmarks and evaluates the efficacy of guidance from one such environmentally sustainable system resting at humanity's doorstep - the biosphere. Taking a holistic view of biomimicry, emulation of and inspiration by life, this work extracts overarching principles of life from academic life science literature using a sociological technique known as constant comparative method. It translates these principles into bio-inspired sustainable engineering guidelines. During this process, it identifies physically rooted measures and metrics that link guidelines to engineering applications. Qualitative validation for principles and guidelines takes the form of review by biology experts and comparison with existing environmentally benign design and manufacturing guidelines. Three select bio-inspired guidelines at three different organizational scales of engineering interest are quantitatively validated. Physical experiments with self-cleaning surfaces quantify the potential environmental benefits generated by applying the first, sub-product scale guideline. An interpretation of a metabolically rooted guideline applied at the product / organism organizational scale is shown to correlate with existing environmental metrics and predict a sustainability threshold. Finally, design of a carpet recycling network illustrates the quantitative environmental benefits one reaps by applying the third, multi-facility scale bio-inspired sustainability guideline. Taken as a whole, this work contributes (1) a set of biologically inspired sustainability principles for engineering, (2) a translation of these principles into measures applicable to design, (3) examples demonstrating a new, holistic form of biomimicry and (4) a deductive, novel approach to environmentally benign engineering. Life, the collection of processes that tamed and maintained themselves on planet Earth's once hostile surface, long ago confronted and solved the fundamental problems facing all organisms. Through this work, it is hoped that humanity has taken one small step toward self-mastery, thus drawing closer to a solution to the latest problem facing all organisms.Ph.D.Committee Chair: Bert Bras; Committee Member: David Rosen; Committee Member: Dayna Baumeister; Committee Member: Janet Allen; Committee Member: Jeannette Yen; Committee Member: Matthew Realf

CD-based microfluidics for primary care in extreme point-of-care settings

We review the utility of centrifugal microfluidic technologies applied to point-of-care diagnosis in extremely under-resourced environments. The various challenges faced in these settings are showcased, using areas in India and Africa as examples. Measures for the ability of integrated devices to effectively address point-of-care challenges are highlighted, and centrifugal, often termed CD-based microfluidic technologies, technologies are presented as a promising platform to address these challenges. We describe the advantages of centrifugal liquid handling, as well as the ability of a standard CD player to perform a number of common laboratory tests, fulfilling the role of an integrated lab-on-a-CD. Innovative centrifugal approaches for point-of-care in extremely resource-poor settings are highlighted, including sensing and detection strategies, smart power sources and biomimetic inspiration for environmental control. The evolution of centrifugal microfluidics, along with examples of commercial and advanced prototype centrifugal microfluidic systems, is presented, illustrating the success of deployment at the point-of-care. A close fit of emerging centrifugal systems to address a critical panel of tests for under-resourced clinic settings, formulated by medical experts, is demonstrated. This emphasizes the potential of centrifugal microfluidic technologies to be applied effectively to extremely challenging point-of-care scenarios and in playing a role in improving primary care in resource-limited settings across the developing world

Basic properties and variability

Giant and supergiant M, S, and C stars are discussed in this survey of research. Basic properties as determined by spectra, chemical composition, photometry, or variability type are discussed. Space motions and space distributions of cool giants are described. Distribution of these stars in our galaxy and those nearby is discussed. Mira variables in particular are surveyed with emphasis on the following topics: (1) phase lag phenomenon; (2) Mira light curves; (3) variations in color indices; (4) determination of multiple periods; (5) correlations between quantities such as period length, light-curve shape, infrared (IR) excess, and visible and IR color diagram; (6) semiregular (SR) variables and different time scales in SR light variations; (7) irregular variable Lb and Lc stars; (8) different time-scale light variations; (9) hydrogen-deficient carbon (HdC) stars, in particular RCB stars; and (10) irreversible changes and rapid evolution in red variable stars

Analysis of non-linear aeroelastic systems using numerical continuation

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