Observer and Particle Transformations and Newton's Laws

A frequently confused point in studies of symmetry violation is the distinction between observer and particle transformations. In this work, we consider a model in which a coefficient in the Standard-Model Extension leads to violations of rotation invariance in Newton's second law. The model highlights the distinction between observer and particle transformations.Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 17-21, 201

Influence of Back-Up Bearings and Support Structure Dynamics on the Behavior of Rotors With Active Supports

This report presents a synopsis of the research work. Specific accomplishments are itemized below: (1) Experimental facilities have been developed. This includes a magnetic bearing test rig and an auxiliary bearing test rig. In addition, components have been designed, constructed, and tested for use with a rotordynamics test rig located at NASA Lewis Research Center. (2) A study of the rotordynamics of an auxiliary bearing supported T-501 engine model was performed. (3) An experimental/simulation study of auxiliary bearing rotordynamics has been performed. (4) A rotordynamical model for a magnetic bearing supported rotor system, including auxiliary bearing effects has been developed and simulation studies performed.(5) A finite element model for a foil bearing has been developed and studies of a rotor supported by foil bearings have been performed. (6) Two students affiliated with this project have graduated with M.S. degrees

Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

Progress over the past year includes the following: A simplified rotor model with a flexible shaft and backup bearings has been developed. A simple rotor model which includes a flexible disk and bearings with clearance has been developed and the dynamics of the model investigated. A rotor model based upon the T-501 engine has been developed which includes backup bearing effects. Parallel simulation runs are being conducted using an ANSYS based finite element model of the T-501. The magnetic bearing test rig is currently floating and dynamics/control tests are being conducted. A paper has been written that documents the work using the T-501 engine model. Work has continued with the simplified model. The finite element model is currently being modified to include the effects of foundation dynamics. A literature search for material on foil bearings has been conducted. A finite element model is being developed for a magnetic bearing in series with a foil backup bearing

Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

Substantial progress has been made toward the goals of this research effort in the past six months. A simplified rotor model with a flexible shaft and backup bearings has been developed. The model is based upon the work of Ishii and Kirk. Parameter studies of the behavior of this model are currently being conducted. A simple rotor model which includes a flexible disk and bearings with clearance has been developed and the dynamics of the model investigated. The study consists of simulation work coupled with experimental verification. The work is documented in the attached paper. A rotor model based upon the T-501 engine has been developed which includes backup bearing effects. The dynamics of this model are currently being studied with the objective of verifying the conclusions obtained from the simpler models. Parallel simulation runs are being conducted using an ANSYS based finite element model of the T-501

A study of the effects of disk flexibility on the rotordynamics of the space shuttle main engine turbo-pumps

Rotor dynamical analyses are typically performed using rigid disk models. Studies of rotor models in which the effects of disk flexibility were included indicate that is may be an important effect for many systems. This issue is addressed with respect to the Space Shuttle Main Engine high pressure turbo-pumps. Finite element analyses have been performed for a simplified free-free flexible disk rotor model and the modes and frequencies compared to those of a rigid disk model. The simple model was then extended to a more sophisticated HPTOP rotor model and similar results were observed. Equations were developed that are suitable for modifying the current rotordynamical analysis program to account for disk flexibility. Some conclusions are drawn from the results of this work as to the importance of disk flexibility on the HPTOP rotordynamics and some recommendations are given for follow-up research in this area

Disk flexibility effects on the rotordynamics of the SSME high pressure turbopumps

Rotordynamical analyses are typically performed using rigid disk models. Studies of rotor models in which the effects of disk flexibility were included indicate that it may be an important effect for many systems. This issue is addressed with respect to the Space Shuttle Main Engine high pressure turbopumps. Finite element analyses were performed for a simplified free-free flexible disk rotor models and the modes and frequencies compared to those of a rigid disk model. Equations were developed to account for disk flexibility in rotordynamical analysis. Simulation studies were conducted to assess the influence of disk flexibility on the HPOTP. Some recommendations are given as to the importance of disk flexibility and for how this project should proceed

New effective interaction for pfpf-shell nuclei and its implications for the stability of the NN=ZZ=28 closed core

The effective interaction GXPF1 for shell-model calculations in the full $pf$ shell is tested in detail from various viewpoints such as binding energies, electro-magnetic moments and transitions, and excitation spectra. The semi-magic structure is successfully described for $N$ or Z=28 nuclei, $^{53}$Mn, $^{54}$Fe, $^{55}$Co and $^{56,57,58,59}$Ni, suggesting the existence of significant core-excitations in low-lying non-yrast states as well as in high-spin yrast states. The results of $N=Z$ odd-odd nuclei, $^{54}$Co and $^{58}$Cu, also confirm the reliability of GXPF1 interaction in the isospin dependent properties. Studies of shape coexistence suggest an advantage of Monte Carlo Shell Model over conventional calculations in cases where full-space calculations still remain too large to be practical.Comment: 29pages, 26figures, to be published in Physical Review

Iron ochre: a pre-catalyst for the cracking of methane

Background: Iron ochres are gelatinous sludges which can cause problems in terms of water management. In this manuscript, the application of iron ochre obtained from a river has been applied to catalytically crack methane – another potential waste product - into two useful products, hydrogen and a magnetic carbon containing composite.<p></p> Results: The powder XRD pattern of the iron ochre was found to be consistent with the expected 2-line ferrihydrite and EDX analysis showed Fe to be a major component although some Si was present. The sample was observed to contain a fraction with a tubular morphology consistent with the presence of extra-cellular biogenic iron oxide formed by leptothrix. Upon exposure to methane at elevated temperatures, the material was found to transform into an active catalyst for hydrogen production yielding a magnetic carbon containing composite material comprising filamentous carbon and encapsulating graphite.<p></p> Conclusion: The application of two waste products – iron ochre and methane – to generate two useful products – hydrogen and a magnetic carbon containing composite- has been demonstrated. Furthermore, the ochre has been shown to comprise tubular morphology extra-cellular biogenic iron oxide which may be of interest in terms of other applications.<p></p&gt

Synchronous dynamics of a coupled shaft/bearing/housing system with auxiliary support from a clearance bearing: Analysis and experiment

This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective of the work is to develop a better understanding of the dynamical behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotordynamical responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotordynamic behavior predicted by the simulation studies. A strategy for reducing synchronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified. The results are presented and discussed

Steady-state dynamic behavior of an auxiliary bearing supported rotor system

This paper investigates the steady-state responses of a rotor system supported by auxiliary bearings in which there is a clearance between the rotor and the inner race of the bearing. A simulation model based upon the rotor of a production jet engine is developed and its steady-state behavior is explored over a wide range of operating conditions for various parametric configurations. Specifically, the influence of rotor imbalance, support stiffness, and damping is studied. It is found that imbalance may change the rotor responses dramatically in terms of frequency contents at certain operating speeds. Subharmonic responses of 2nd order through 10th order are all observed except the 9th order. Chaotic phenomenon is also observed. Jump phenomena (or double-valued responses) of both hard-spring type and soft-spring type are shown to occur at low operating speeds for systems with low auxiliary bearing damping or large clearance even with relatively small imbalance. The effect of friction between the shaft and the inner race of the bearing is also discussed