This paper presents a new 2D FE formulation to treat geometrically nonlinear problems. The new formulation will use nodal coordinates as basic variables to address the limitation suffered by the existing FE methods in dealing with large displacement and rotation, where they solve for nodal displacements. Thus, the errors caused by approximation in kinematic relationship and the accumulated numerical errors arising from the incremental solution procedure of existing methods can be eliminated. 2D formulation is in progress while results in 1D are available.
Xiaoyi Dong (sunne)
SHAPELETS: a new method for the galaxy imaging analysis
Galaxies are most common objects in our universe. Studying galaxies relies on spectroscopic or photometric (imaging) methods. Photometry is much less time-consuming comparing with spectroscopy method, it is ideal to study galaxies classification and variety of galaxies properties at least in statistic sense. Many multi-filter imaging surveys have been done or are being carried on (such as Sloan Digital Sky Survey and CFHT Legacy Survey). Benefits of using multi-filter imaging data are many, for example, galaxies can be classified based on colour-colour diagram. But different filters usually have different PSFs (point spread functions), which causes different imaging have different physical scales. A general method to solve the different PSFs problem is to convolve image of smaller PSFs to match the image of the widest PSF, with the sacrifice of the spatial resolution. SHAPELETS is a new imaging analysis method which is known for studying weak lensing image. We borrow this method to study nearby galaxies. The basic ideal of SHAPELETS is to decompose the image into a series basic functions, which are Gaussian function weighted Hermite polynomial and are orthonormal. The image can be reconstructed using SHAPELETS coefficients with or without a PSF. After a careful test of SHAPELETS, I conclude that SHAPELETS can reconstruct a fair good model to represent the original image, and overall meets the requirement of our work.
Charge Parity Violation in Bottom Physics
The predominance of matter over antimatter in the universe is know as the baryon asymmetry. Weak processes which violate the charge-parity (CP) symmetry may help explain this phenomenon. These processes are included in the current Standard Model (SM) of particle physics, however they are not predicted to be sufficient to account for the observed asymmetry. Many new models beyond the SM include additional sources of CP violation which may account for this difference. This makes measurement of CP violating parameters an important test for physics beyond the SM.In this talk I will explain the CP symmetry, how it is broken, and how it can be measured using b-meson decays.
Chandra X-ray Observations of Two Unusual BAL Quasars
Reporting on the results of X-ray observations which do not detect two unusual, luminous FeLoBAL quasars. To block the X-ray emission from these quasars requires high and tightly constrained column densities. To account for the observed characteristics of the quasars requires constrained ionization parameters and density. Based on models using CLOUDY photoionization simulations, the constraints match the observations.
T2K – the next generation long baseline neutrino oscillation experiment
I will provide an overview of the phenomenon of neutrino oscillations, show recent results, and talk about future experiments (mostly T2K).
Invited Speaker: Dr. Randy Lewis
Two-bottomed baryons and exotic light mesons
In nature, all quarks are confined within composite objects. Many such objects have been observed, but some theoretical expectations remain unconfirmed by experiment. What is the status of our understanding in those cases? The vital role of computational theory (i.e. “lattice QCD”) will be discussed through two examples: one involving a pair of heavy quarks and the other with only light quarks.
Microwave Measurement of the n=2 Triplet P Fine-Structure of Helium using Ramsey Separated Oscillatory Fields
The Ramsey method of separated oscillatory fields is used to make a very precise microwave measurement of the n=2 triplet P J=1-to-J=2 interval in helium. The excellent signal-to-noise obtained in these measurements allows for extensive studies of systematic effects. The separated-oscillatory-field method allows for subnatural linewidths and provides the ability to vary the lineshape to further study systematic effects. We are in the final stages of completing themeasurement of the 2.29-GHz interval at a precision of less than 500 Hz. Comparison between precise measurements of the n=2 triplet P fine structure and theoretical predictions will allow for a precise determination of the fine-structure constant when the current large discrepancy between experiment and theory is resolved.
Radiation Screening Effect and Noise factor on Black Hole mass estimates
We study the sensitivity of Super-Massive Black Hole mass estimates to background noise and the quasar’s Eddington ratio. Using a sample of high signal-to-noise ratio quasar spectra from the SDSS DR3, we examine the effect of added background noise on our ability to accurately reconstruct the quasar spectra using Principal Component Analysis, PCA. We study the dispersion in the resulting BH mass estimate as the noise is increased. We also take into account the effect of the radiation screening force on the BH Virial mass estimate. We modify the previously generated scaling relationship which estimates black hole mass.
Trends in structure and stability of atomic clusters
The properties of atomic cluster vary based on the element and the number of atoms it is made of. By doing a series of unbiased global search with the high-performance technology provided by SHARCNET, we study the structural trends for different groups of atomic clusters and come up with factors that govern cluster structure and stability.
Measuring gravity with a single state atom interferometer
We describe a method of measuring gravity using a single state atom interferometer. Two standing wave pulses separated by T are applied to a sample of laser cooled rubidium atoms. The atoms evolve into a superposition of momentum states separated by 2hbar k, producing a density grating in the sample that dephases due to the velocity distribution of the sample. The grating that rephases at t= 2T due to the second pulse has a period of lambda/2. This grating is detected by backscattering a readout pulse into a balanced heterodyne detector. The phase of the light is measured against an optical local oscillator. The accumulation of phase as a function of T can be used to find a value for gravity. We have measured g to a precision of 10ppm on a time scale of 20ms by acquiring data over 10 minutes. We discuss improvements to the experiment via increasing time scale, vibration isolating and shielding and correction the RF phase to compensate for mirror vibrations.
Wave Function Simulations of a Matter Wave Interferometer
We present simulations to understand a single-state atom interferometer used to measure the atomic recoil frequency with laser cooled atoms. In the experiment, a standing wave laser is pulsed on at t = 0 which creates a superposition of momentum states. At t = T, a second standing wave pulse diffracts the momentum states again so that a density grating is formed in the vicinity of t = 2T. This grating is associated with the interference of momentum states separated by 2 ħ k. A traveling wave read-out pulse is applied to the sample at this time and the backscattered light from the grating is detected as the echo signal. The amplitude of the echo signal is periodic at the atomic recoil frequency and the duration of the echo envelope is related to the velocity distribution in the sample. Our goal is to model several aspects of the echosignal, both in the short pulse (Raman-Nath) and long pulse (Bragg) regimes, such as the dependence of the echo amplitude on the Rabi frequency, pulse length and spontaneous emission.
Invited Speaker: Dr. Tzahi Yavin
How Strong is the Strong Nuclear Force? In this presentation
I will discuss the strong nuclear force that binds quarks into nucleons and hadrons as described by the theory of quantum chromodynamics (QCD), and how its strength can be determined quite accurately from the decays of the tau lepton into hadrons.