A Unification of Models of Tethered Satellites

In this paper, different conservative models of tethered satellites are related mathematically, and it is established in what limit they may provide useful insight into the underlying dynamics. An infinite dimensional model is linked to a finite dimensional model, the slack-spring model, through a conjecture on the singular perturbation of tether thickness. The slack-spring model is then naturally related to a billiard model in the limit of an inextensible spring. Next, the motion of a dumbbell model, which is lowest in the hierarchy of models, is identified within the motion of the billiard model through a theorem on the existence of invariant curves by exploiting Moser's twist map theorem. Finally, numerical computations provide insight into the dynamics of the billiard model

Mission design for a ballistic slow flyby Comet Encke 1980

Preliminary mission analyses for a proposed 1980 slow flyby (7-9 km/s) of comet Encke are presented. Among the topics covered are science objectives, Encke's physical activity and ephemeris accuracy, trajectory and launch-window analysis, terminal guidance, and spacecraft concepts. The nominal mission plan calls for a near-perihelion intercept with two spacecraft launched on a single launch vehicle. Both spacecraft will arrive at the same time, one passing within 500 km from Encke's nucleus on its sunward side, the other cutting through the tail region. By applying a small propulsive correction about three weeks after the encounter, it is possible to retarget both spacecraft for a second Encke intercept in 1984. The potential science return from the ballistic slow flyby is compared with other proposed mission modes for the 1980 Encke flyby mission, including the widely advocated slow flyby using solar-electric propulsion. It is shown that the ballistic slow flyby is superior in every respect

Inducer dynamics full-flow, full-admission hydraulic turbine drive Interim report for tasks 1, 2, and 3

Hydrodynamical and mechanical design layout for two-speed hydraulic turbine inducer, computer simulation of pumping system and test facility performance, and study of demonstration uni

Selective demarketing: When customers destroy value.

Selective demarketing is a strategic option for firms to manage customers who are or are likely to be a poor fit with its offering. Research has investigated related areas such as customer profitability and relationship dissolution but, as yet, studies have not offered a robust conceptualisation of selective demarketing. Based on research into value co-destruction, this study argues that these customers effectively destroy value by misusing or misunderstanding how to integrate their operant resources with those of the firm. As firms exist within a wider service system, this failure to integrate resonates throughout the system. To demarket selectively, firms use higher order operant resources to disengage and discourage these customers. This study offers a novel conceptualisation of selective demarketing and extends research on value destruction through adopting a firm and systems perspective

The role of ice particle shapes and size distributions in the single scattering properties of cirrus clouds

The roles of ice particle size distributions (SDs) and particle shapes in cirrus cloud solar radiative transfer are investigated by analyzing SDs obtained from optical array probe measurements (particle sizes larger than 20–40 μm) during intensive field observations of the International Cirrus Experiment, the European Cloud and Radiation Experiment, the First ISCCP Regional Experiment, and the Central Equatorial Pacific Experiment. It is found that the cloud volume extinction coefficient is more strongly correlated with the total number density than with the effective particle size. Distribution-averaged mean single scattering properties are calculated for hexagonal columns, hexagonal plates, and polycrystals at a nonabsorbing (0.5 μm), moderately absorbing (1.6 μm), and strongly absorbing (3.0 μm) wavelength. At 0.5 μm (1.6 μm) (3.0 μm), the spread in the resulting mean asymmetry parameters due to different SDs is smaller than (comparable to) (smaller than) the difference caused by applying different particle shapes to these distributions. From a broadband solar radiative transfer point of view it appears more important to use the correct particle shapes than to average over the correct size distributions

STAT3 gain-of-function mutations connect leukemia with autoimmune disease by pathological NKG2Dhi CD8+ T cell dysregulation and accumulation

The association between cancer and autoimmune disease is unexplained, exemplified by T cell large granular lymphocytic leukemia (T-LGL) where gain-of-function (GOF) somatic STAT3 mutations correlate with co-existing autoimmunity. To investigate whether these mutations are the cause or consequence of CD

The local magnetic moments and hyperfine magnetic fields in disordered metal-metalloid alloys

The local magnetic moments and hyperfine magnetic fields (HFF) in the ordered alloys Fe_{15}Sn and Fe_{15}Si are calculated with the first-principles full-potential linear augmented plane wave (FP LAPW) method. The results are compared with the experimental data on Fe-M (M=Si, Sn) disordered alloys at small metalloid concentration. The relaxation of the lattice around the impurity and its influence on the quantities under consideration are studied. The mechanism of the local magnetic moment formation is described. It is proved that the main distinction between these alloys is connected with the different lattice parameters. Three contributions to the HFF are discussed: the contributions of the core and valence electron polarization to the Fermi-contact part, and the contibution from the orbital magnetic moment.Comment: 3 pages, 3 figures, submitted to Phys. Rev.