Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session S20: Undergraduate Session III |
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Sponsoring Units: SPS Chair: Kendra Rand, American Institute of Physics Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), Director's Row 48 |
Monday, April 14, 2008 2:06PM - 2:18PM |
S20.00001: 3D Quantitative Nanoscale Imaging via Coherent X-Rays Kevin Raines, Changyong Song, Huaidong Jiang, Adrian Mancusco, Rui Xu, Jianwei Miao, Chien-Chun Chen, Ting-Kuo Lee, Tetsuya Ishikawa Coherent x-ray diffraction microscopy (CXDM) promises to become an important imaging technique, particularly with the development of FELs. Indeed, recently there has been much interest in harnessing CXDM to quantitatively image in 3D such biological samples as single cells, organelles, and eventually macromolecules. Such images are obtained by rotating a specimen about an axis, resulting in its 3D diffraction pattern in cylindrical coordinates. Thus interpolating the data accurately onto a Cartesian grid is an essential step to 3D image reconstruction. I have developed a gridding-based interpolation scheme that yields a superior reconstruction from a limited and incomplete set of diffraction patterns. This interpolation algorithm is generalizable to a variety of imaging and interpolation applications. The effect of various degrees of angular under-sampling and the missing wedge upon resolution in each dimension will also be discussed. [Preview Abstract] |
Monday, April 14, 2008 2:18PM - 2:30PM |
S20.00002: Using a Large Ring Laser Gyroscope (RLG) to Understand the Torsional Components of Near-Field Seismic Events Adam Jacobs Seismographs are able to accurately measure translational components of seismic events, i.e. the North-South, East-West, and Up-Down (z) components. However, there has recently been a renewed interest in measuring the torsional components of such events. Preliminary results from a triangular, large ring laser (measuring 17 meters on a side) suggest that RLGs could be a vital tool in opening up this relatively unexplored aspect of seismology. The ring laser has produced data similar to that of seismographs in response to three near-field earthquakes in Tennessee, the Gulf of Mexico, and Mexico. In addition to this, Fourier analysis of voltage variations caused by perturbations of the ring laser during these near-field events has yielded several interesting results not given by traditional seismographs. These results include the increased effectiveness of RLGs for near-field measurements versus far-field, the torsional resonances excited by the detected earthquakes, and perhaps the mechanism which generates torsion in an earthquake. The ring laser's results, their implications, and a potential model will be presented. [Preview Abstract] |
Monday, April 14, 2008 2:30PM - 2:42PM |
S20.00003: Chaos in the Relativistic Three-Body Problem Miriam Conde, J.J. Campbell, David Tanner, David Neilsen We investigate chaos in general relativity by studying three-body interactions using the post-Newtonian formalism.~ The initial data consist of a binary pair (with equal or unequal masses) that scatters a third object that comes from infinity, and these data are parametrized by the orbital phase of the binary pair and the initial impact parameter of the third body.~ The final state of the system is characterized by quantities measurable at infinity, and we examine the sensitivity of these quantities on the initial parameters. Finally, we calculate Lyapunov exponents directly from the simulations to quantify the chaotic behavior. [Preview Abstract] |
Monday, April 14, 2008 2:42PM - 2:54PM |
S20.00004: Relativistic Corrections and Chaos in the Three-Body Problem J.J. Campbell, David Neilsen, Miriam Neubauer, David Tanner In classical Newtonian gravity, the three-body problem is known to be chaotic for general initial data. We investigate the existence of chaos for the three-body problem in general relativity using the first and second post-Newtonian approximations. Our initial data consists of a third object scattering from a binary pair and are parameterized by an impact parameter and phase angle. The Hamiltonian equations of motion are integrated using geometric methods and we extract gauge-independent quantities at infinity. We present results that characterize chaos in general relativity. [Preview Abstract] |
Monday, April 14, 2008 2:54PM - 3:06PM |
S20.00005: Six degree-of-freedom thrust sensor for hybrid rocket. Joshua Wilson Thrust is the reactive force experienced by a rocket due to the ejection of high velocity matter. The Hybrid Rocket Facility at the University of Arkansas at Little Rock (UALR) uses strain gauges mounted to an s-beam to measure axial direction thrust of the rocket. A new six degree of freedom thrust sensor has been built for the UALR Hybrid Rocket Facility. The six degrees of freedom are the thrust force components in the three spacial directions (F$_{x}$, F$_{y}$, F$_{z})$ plus the three moments (roll, pitch, yaw). Even though the majority of the rocket's thrust is in the axial direction, the components in the other directions are non-zero, and must be measured to account for the total work done by the rocket motor. The sensor design and fabrication are now complete. Calibration of the load cells on each of the six uni-axial legs of the sensor and any preliminary data available will be presented. [Preview Abstract] |
Monday, April 14, 2008 3:06PM - 3:18PM |
S20.00006: Synthesis, Structural, and Electrochemical Stability Studies of Nanocrystalline 5V Lithiated Oxides for Asymmetric Supercapacitor William Parker, Huiming Wu, Rambabu Bobba For the development of asymmetric (hybrid) supercapacitor, we have synthesized nanoscale double substituted LiNi$_{ Y}$Co$_{1-2 Y}$Mn$_{1+ Y}$O$_{4}$ ($Y$=0.05, 0.1, 0.25 and 0.45) spinels using mechanochemical, hydrothermal, microwave assisted combustion aided procedures. The samples have been characterized by XRD, TEM, and XAFS. Lattice parameter of the spinels increased with nickel content, and decreased from 400 to 600\r{ }C, at which temperature the particle size is $\approx $20nm. The sample with composition LiNi$_{0.45}$Co$_{0.1}$Mn$_{1.45}$O$_{4}$ has shown the best electrochemical performance, with redox potential of 4.6V, capacity of 129.6mAhg$^{-1}$, cyclability of 99.6{\%} per cycle, and retained the capacity up to 1 $C$ rate. The XANES of Mn and $M$ as a function of $x$ showed that the high voltage ($\sim$5 V) in the cathode materials of an Li secondary battery is due to the oxidation of $M^{3+}$ to $M^{4+}$ ($M$=Co) and $M^{2+}$ to $M^{4+}$ (in the case of $M$=Ni). The EXAFS analysis revealed that Ni$^{2+}$ is oxidized to Ni$^{4+}$ via the Ni$^{3+}$ state with a Jahn--Teller distorted Ni$^{3+}$--O octahedron. A hybrid device employing nanostructured LiNi$_{ Y}$Co$_{1-2 Y}$Mn$_{1+ Y}$O$_{4}$ /polymer electrolyte/nanoporous carbon black (NCB) powders was assembled. grant {\#} W911NF-07-1-0426 [Preview Abstract] |
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