Paper Session III-C - A New Old Way to Space: Taking the Best From the Past to Forge Ahead into the Future

The next step in space exploration must be on a scale that has never been experienced before. In order to construct a fully functioning spaceport, tremendous amounts of cargo and materials as well as large numbers of people will have to be transported into orbit. The size of the program and the spaceport that will have to be built will be orders of magnitude greater than anything yet accomplished. Unlike ISS Alpha, the spaceport will have to support more than just research. For it to be economically feasible, it must provide space and services to a number of different operations. Manufacturing, tourism, research, construction, commerce and exploration are just some of the activities that will take place on or from the spaceport. These requirements dictate that the spaceport be able to provide space and services for over 300 people to live and work. If the spaceport is assumed to be a circular design providing artificial gravity such as the one proposed by von Braun and exemplified in 2001: A Space Odyssey it could easily exceed 500 meters in diameter. The effort to lift the amount of material needed to construct a spaceport of this size is staggering. Current vehicles and methods will be unable to achieve the needed volume or launch frequency. A new set of systems and vehicles must be developed. The lessons of the past must be re-evaluated and integrated into the new program. By combining methods developed for Apollo, SkyLab, Mars Pathfinder and the Space Shuttle with modern materials and technology a new “old way” to lift mass into space becomes possible. This paper will explore this new “old way” and how the achievements of the past will help illuminate the way into the future

Paper Session III-C - Innovative Financing of a Large Space Project

This paper addresses the changes to the Space Frontier Operations, Inc. (SFO) Space Exploration Plan, (SEP) that was initially presented at the 37th. Space Congress in 1999. Progress since last year will be presented briefly and the progress made in finding the correct financing vehicles will be presented in detail. The SFO Space Exploration Project starts off as an international project that will present unique and difficult challenges to both the space and financial communities. The effects of these challenges will be discussed along with their impact to the process of raising capital for a project of this nature. The rationale behind establishing a separate but complimentary corporation will be discussed. The relationship between the commercial corporation and SFO will be delineated. It will be shown that complimentary roles are not only possible but also highly desirable. The way in which the SEP fits into the standard protocols used by the finance industry will be discussed. As the project proceeds to completion the issue of traditional financing with an Initial Public Offering will be addressed along with the possibility of bringing in one or more partners – either commercial or governmental. Finally, the work of the supporting commercial corporation will be presented and the current status of the two corporations will be discussed

Flight Mechanics and Control of Escape Manoeuvres in Hummingbirds. I. Flight Kinematics

Hummingbirds are nature’s masters of aerobatic manoeuvres. Previous research shows that hummingbirds and insects converged evolutionarily upon similar aerodynamic mechanisms and kinematics in hovering. Herein, we use three-dimensional kinematic data to begin to test for similar convergence of kinematics used for escape flight and to explore the effects of body size upon manoeuvring. We studied four hummingbird species in North America including two large species (magnificent hummingbird, Eugenes fulgens, 7.8 g, and blue-throated hummingbird, Lampornis clemenciae, 8.0 g) and two smaller species (broad-billed hummingbird, Cynanthus latirostris, 3.4 g, and black-chinned hummingbirds Archilochus alexandri, 3.1 g). Starting from a steady hover, hummingbirds consistently manoeuvred away from perceived threats using a drastic escape response that featured body pitch and roll rotations coupled with a large linear acceleration. Hummingbirds changed their flapping frequency and wing trajectory in all three degrees of freedom on a stroke-by-stroke basis, likely causing rapid and significant alteration of the magnitude and direction of aerodynamic forces. Thus it appears that the flight control of hummingbirds does not obey the ‘helicopter model’ that is valid for similar escape manoeuvres in fruit flies. Except for broad-billed hummingbirds, the hummingbirds had faster reaction times than those reported for visual feedback control in insects. The two larger hummingbird species performed pitch rotations and global-yaw turns with considerably larger magnitude than the smaller species, but roll rates and cumulative roll angles were similar among the four species

Flight Mechanics and Control of Escape Manoeuvres in Hummingbirds. II. Aerodynamic Force Production, Flight Control and Performance Limitations

The superior manoeuvrability of hummingbirds emerges from complex interactions of specialized neural and physiological processes with the unique flight dynamics of flapping wings. Escape manoeuvring is an ecologically relevant, natural behaviour of hummingbirds, from which we can gain understanding into the functional limits of vertebrate locomotor capacity. Here, we extend our kinematic analysis of escape manoeuvres from a companion paper to assess two potential limiting factors of the manoeuvring performance of hummingbirds: (1) muscle mechanical power output and (2) delays in the neural sensing and control system. We focused on the magnificent hummingbird (Eugenes fulgens, 7.8 g) and the black-chinned hummingbird (Archilochus alexandri, 3.1 g), which represent large and small species, respectively. We first estimated the aerodynamic forces, moments and the mechanical power of escape manoeuvres using measured wing kinematics. Comparing active-manoeuvring and passive-damping aerodynamic moments, we found that pitch dynamics were lightly damped and dominated by the effect of inertia, while roll dynamics were highly damped. To achieve observed closed-loop performance, pitch manoeuvres required faster sensorimotor transduction, as hummingbirds can only tolerate half the delay allowed in roll manoeuvres. Accordingly, our results suggested that pitch control may require a more sophisticated control strategy, such as those based on prediction. For the magnificent hummingbird, we estimated that escape manoeuvres required muscle mass-specific power 4.5 times that during hovering. Therefore, in addition to the limitation imposed by sensorimotor delays, muscle power could also limit the performance of escape manoeuvres

NUMERICAL SIMULATION OF DUCTILE CRACK GROWTH IN PIPELINE STEELS

ABSTRACT This paper presents numerical studies on stable crack extension of high toughness gas pipeline steels (X80) using the 2D and 3D computational cell approach. The GursonTvergaard dilatant plasticity model for voided materials is used to describe the degradation of material stress capacity. Fixedsize, computational cell elements defined over a thin layer at the crack plane provide an explicit length scale for the continuum damage process. Outside this layer, the material is modeled as undamaged by void growth. The key micromechanics parameters are D, the thickness of the computational cell layer, and f 0 , the initial cell porosity. Calibration of these parameters is conducted using analysis of ductile tearing from testing of Charpy-sized bending specimens. The resulting computational model enables the study of effects on crack growth of specimen size, geometry and loading mode. Computational and experimental studies are described for shallow and deep DWTT (drop weight tear test) specimens under quasi-static loading conditions

Volumetric imaging of shark tail hydrodynamics reveals a three-dimensional dual-ring vortex wake structure

Understanding how moving organisms generate locomotor forces is fundamental to the analysis of aerodynamic and hydrodynamic flow patterns that are generated during body and appendage oscillation. In the past, this has been accomplished using two-dimensional planar techniques that require reconstruction of three-dimensional flow patterns. We have applied a new, fully three-dimensional, volumetric imaging technique that allows instantaneous capture of wake flow patterns, to a classic problem in functional vertebrate biology: the function of the asymmetrical (heterocercal) tail of swimming sharks to capture the vorticity field within the volume swept by the tail. These data were used to test a previous three-dimensional reconstruction of the shark vortex wake estimated from two-dimensional flow analyses, and show that the volumetric approach reveals a different vortex wake not previously reconstructed from two-dimensional slices. The hydrodynamic wake consists of one set of dual-linked vortex rings produced per half tail beat. In addition, we use a simple passive shark-tail model under robotic control to show that the three-dimensional wake flows of the robotic tail differ from the active tail motion of a live shark, suggesting that active control of kinematics and tail stiffness plays a substantial role in the production of wake vortical patterns

Schwarzschild black hole lensing

We study strong gravitational lensing due to a Schwarzschild black hole. Apart from the primary and the secondary images we find a sequence of images on both sides of the optic axis; we call them {\em relativistic images}. These images are formed due to large bending of light near r = 3M (the closest distance of approach r_o is greater than 3M). The sources of the entire universe are mapped in the vicinity of the black hole by these images. For the case of the Galactic supermassive ``black hole'' they are formed at about 17 microarcseconds from the optic axis. The relativistic images are not resolved among themselves, but they are resolved from the primary and secondary images. However the relativistic images are very much demagnified unless the observer, lens and source are very highly aligned. Due to this and some other difficulties the observation of these images does not seem to be feasible in near future. However, it would be a great success of the general theory of relativity in a strong gravitational field if they ever were observed and it would also give an upper bound, r_o = 3.21 M, to the compactness of the lens, which would support the black hole interpretation of the lensing object.Comment: RevTex, 5 eps files are included, observational difficulties are discussed and there are some changes in presentatio

Simultaneous X-ray and UV spectroscopy of the Seyfert 1 galaxy NGC 5548.II. Physical conditions in the X-ray absorber

We present the results from a 500 ks Chandra observation of the Seyfert 1 galaxy NGC 5548. We detect broadened emission lines of O VII and C VI in the spectra, similar to those observed in the optical and UV bands. The source was continuously variable, with a 30 % increase in luminosity in the second half of the observation. No variability in the warm absorber was detected between the spectra from the first 170 ks and the second part of the observation. The velocity structure of the X-ray absorber is consistent with the velocity structure measured simultaneously in the ultraviolet spectra. We find that the highest velocity outflow component, at -1040 km/s, becomes increasingly important for higher ionization parameters. This velocity component spans at least three orders of magnitude in ionization parameter, producing both highly ionized X-ray absorption lines (Mg XII, Si XIV) as well as UV absorption lines. A similar conclusion is very probable for the other four velocity components. Based upon our observations, we argue that the warm absorber probably does not manifest itself in the form of photoionized clumps in pressure equilibrium with a surrounding wind. Instead, a model with a continuous distribution of column density versus ionization parameter gives an excellent fit to our data. From the shape of this distribution and the assumption that the mass loss through the wind should be smaller than the accretion rate onto the black hole, we derive upper limits to the solid angle as small as 10^{-4} sr. From this we argue that the outflow occurs in density-stratified streamers. The density stratification across the stream then produces the wide range of ionization parameter observed in this source. Abridged.Comment: 21 pages, 12 figures accepted for publication in A&

Synergy Between Intercellular Communication and Intracellular Ca2+ Handling in Arrhythmogenesis

Calcium is the primary signalling component of excitation-contraction coupling, the process linking electrical excitability of cardiac muscle cells to coordinated contraction of the heart. Understanding Ca2þ handling processes at the cellular level and the role of intercellular communication in the emergence of multicellular synchronization are key aspects in the study of arrhythmias. To probe these mechanisms, we have simulated cellular interactions on large scale arrays that mimic cardiac tissue, and where individual cells are represented by a mathematical model of intracellular Ca2þ dynamics. Theoretical predictions successfully reproduced experimental findings and provide novel insights on the action of two pharmacological agents (ionomycin and verapamil) that modulate Ca2þ signalling pathways via distinct mechanisms. Computational results have demonstrated how transitions between local synchronisation events and large scale wave formation are affected by these agents. Entrainment phenomena are shown to be linked to both ntracellular Ca2þ and coupling-specific dynamics in a synergistic manner. The intrinsic variability of the cellular matrix is also shown to affect emergent patterns of rhythmicity, providing insights into the origins of arrhythmogenic Ca2þ perturbations in cardiac tissue in situ