Bearing Loads in a Vehicular Flywheel Battery

Radial and axial rotor support bearings are critical elements in flywheel batteries for vehicle applications. This paper discusses the quantification of bearing loads required for the development of optimal bearing designs, particularly magnetic bearings. The primary contributors to bearing loads are shown to be vehicle shock, vibration, maneuvering, and gyrodynamics. Emphasis is placed on transit bus applications. Available data for each is presented, including actual measurements made on buses, and a detailed analysis of gyrodynamics.Center for Electromechanic

Factorial Economic Planning Applied to Agricultural Experimentation

Innovation may be limited by the scarceness of resources, such as financial, homogeneous area, skilled labor or other research needs, for example the difficulty in experimental control of large areas in the field. In research areas such as chemistry and physics, designs are used in such a way that when compared to the agronomic designs, they result in a reduced number of experimental units, which in this work are called economic designs. Thus, the objective of this study was to identify significant factors and effects (p-valu

Liquid-metal-cooled, curved-crystal monochromator for Advanced Photon Source bending-magnet beamline 1-BM

The authors describe a horizontally focusing curved-crystal monochromator that invokes a 4-point bending scheme and a liquid-metal cooling bath. The device has been designed for dispersive diffraction and spectroscopy in the 5--20 keV range, with a predicted focal spot size of {le} 100 {micro}m. To minimize thermal distortions and thermal equilibration time, the 355 x 32 x 0.8 mm crystal will be nearly half submerged in a bath of Ga-In-Sn-Zn alloy. The liquid metal thermally couples the crystal to the water-cooled Cu frame, while permitting the required crystal bending. Calculated thermal profiles and anticipated focusing properties are discussed

Investigation of A1g phonons in YBa2Cu3O7 by means of LAPW atomic-force calculations

We report first-principles frozen-phonon calculations for the determination of the force-free geometry and the dynamical matrix of the five Raman-active A1g modes in YBa2Cu3O7. To establish the shape of the phonon potentials atomic forces are calculated within the LAPW method. Two different schemes - the local density approximation (LDA) and a generalized gradient approximation (GGA) - are employed for the treatment of electronic exchange and correlation effects. We find that in the case of LDA the resulting phonon frequencies show a deviation from experimental values of approximately -10%. Invoking GGA the frequency values are significantly improved and also the eigenvectors are in very good agreement with experimental findings.Comment: 15 page

Design of an Agile Unmanned Combat Vehicle - A Product of the DARPA UGCV Program

The unmanned ground combat vehicle (UGCV) design evolved by the SAIC team on the DARPA UGCV Program is summarized in this paper. This UGCV design provides exceptional performance against all of the program metrics and incorporates key attributes essential for high performance robotic combat vehicles. This performance includes protection against 7.62 mm threats, C130 and CH47 transportability, and the ability to accept several relevant weapons payloads, as well as advanced sensors and perception algorithms evolving from the PerceptOR program. The UGCV design incorporates a combination of technologies and design features, carefully selected through detailed trade studies, which provide optimum performance against mobility, payload, and endurance goals without sacrificing transportability, survivability, or life cycle cost. The design was optimized to maximize performance against all Category I metrics. In each case, the performance of this design was validated with detailed simulations, indicating that the vehicle exceeded the Category I metrics. Mobility metrics were analyzed using high fidelity VisualNastran vehicle models, which incorporate the suspension control algorithms and controller cycles times. DADS/Easy 5 3-D models and ADAMS simulations were also used to validate vehicle dynamics and control algorithms during obstacle negotiation

Band-structure trend in hole-doped cuprates and correlation with Tcmax

By calculation and analysis of the bare conduction bands in a large number of hole-doped high-temperature superconductors, we have identified the energy of the so-called axial-orbital as the essential, material-dependent parameter. It is uniquely related to the range of the intra-layer hopping. It controls the Cu 4s-character, influences the perpendicular hopping, and correlates with the observed Tc at optimal doping. We explain its dependence on chemical composition and structure, and present a generic tight-binding model.Comment: 5 pages, Latex, 5 eps figure

Active Magnetic Bearings for Energy Storage Systems for Combat Vehicles

Advanced energy storage systems for electric guns and other pulsed weapons on combat vehicles present significant challenges for rotor bearing design, Active magnetic bearings (AMBs) present one emerging bearing option with major advantages in terms of lifetime and rotational speed, and also favorably integrate into high-speed flywheel systems. The Department of Defense Combat Hybrid Power Systems (CHPS) program serves as a case study for magnetic bearing applications on combat vehicles. The University of Texas at Austin Center for Electromechanics (UT-CEM) has designed active magnetic bearing actuators for use in a 5 MW flywheel alternator with a 318 kg (700 lb), 20000 rpm rotor. To minimize CHPS flywheel size and mass, a topology was chosen in which the rotating portion of the flywheel is located outside the stationary components. Accordingly, magnetic bearing actuators are required which share this configuration. Because of inherent low loss and nearly linear force characteristics, UT-CEM has designed and analyzed permanent magnet bias bearing actuators for this application. To verify actuator performance, a nonrotating bearing test fixture was designed and built which permits measurement of static and dynamic force. An AMB control system was designed to provide robust, efficient magnetic levitation of the CHPS rotor over a wide range of operating speeds and disturbance inputs, while minimizing the occurrence of backup bearing touchdowns. This paper discusses bearing system requirements, actuator and controller design, and predicted performance; it also compares theoretical vs. measured actuator characteristicsCenter for Electromechanic

T-cell Subsets and Antifungal Host Defenses

It has been long appreciated that protective immunity against fungal pathogens is dependent on activation of cellular adaptive immune responses represented by T lymphocytes. The T-helper (Th)1/Th2 paradigm has proven to be essential for the understanding of protective adaptive host responses. Studies that have examined the significance of regulatory T cells in fungal infection, and the recent discovery of a new T-helper subset called Th17 have provided crucial information for understanding the complementary roles played by the various T-helper lymphocytes in systemic versus mucosal antifungal host defense. This review provides an overview of the role of the various T-cell subsets during fungal infections and the reciprocal regulation between the T-cell subsets contributing to the tailored host response against fungal pathogens