14,293 research outputs found
Laser-induced thermal acoustics (LITA) signals from finite beams
Laser-induced thermal acoustics (LITA) is a four-wave mixing technique that may be employed to measure sound speeds, transport properties, velocities, and susceptibilities of fluids. It is particularly effective in high-pressure gases (>1 bar). An analytical expression for LITA signals is derived by the use of linearized equations of hydrodynamics and light scattering. This analysis, which includes full finite-beam-size effects and the optoacoustic effects of thermalization and electrostriction, predicts the amplitude and the time history of narrow-band time-resolved LITA and broadband spectrally resolved (multiplex) LITA signals. The time behavior of the detected LITA signal depends significantly on the detection solid angle, with implications for the measurement of diffusivities by the use of LITA and the proper physical picture of LITA scattering. This and other elements of the physics of LITA that emerge from the analysis are discussed. Theoretical signals are compared with experimental LITA data
Using Laboratory Experiments For Policy Making: An Example From The Georgia Irrigation Reduction Auction
In April 2000, the Georgia legislature passed a law requiring that the state use an unspecified "auction-like process" to pay some farmers to suspend irrigation in declared drought years. In response, we conducted a series of laboratory and field experiments to test a variety of auction procedures. This paper reports the results of these experiments, and how they were used by the policy makers who determined the auction procedures. Experimental results are compared with farmers' bidding behavior in the state-run irrigation auction conducted in March 2001. Working Paper # 2002-00
MULTIPAC, a multiple pool processor and computer for a spacecraft central data system, phase 2 Final report
MULTIPAC, multiple pool processor and computer for deep space probe central data syste
Signatures of quantum chaos in rare-earth elements: I. Characterization of the Hamiltonian matrices and coupling matrices of Ce I and Pr I using the statistical predictions of Random Matrix Theory.
Using the relativistic configuration interaction Hartree–Fock method the
Hamiltonian matrices of Ce I, J = 4±, and Pr I, J = 11/2±, are studied.
These matrices can be characterized as sparse, banded matrices, with a
leading diagonal. Diagonalization of the Hamiltonian results in a set of
energy eigenvalues and corresponding eigenvectors and the purpose of this
investigation will be to characterize the Hamiltonian matrices and coupling
matrices of Ce I and Pr I, for both ls and jj coupling representations, using
various statistical predictions of Random Matrix Theory
A computational investigation of the impact of aberrated Gaussian laser pulses on electron beam properties in laser-wakefield acceleration experiments
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98752/1/PhysPlasmas_18_053110.pd
Exam 2 Strategy
After students take their first exam in an accounting course, tax accounting and intermediate accounting in this case, their reactions to their test scores may be varied. This is their first major assessment of how they have performed in the class. The students in the class near the high end of the grading scale are going to be satisfied with their score. Yet the overwhelming majority of students should be thinking about how they can do better on the next exam or an “Exam 2 strategy”. This paper describes a process which allows students to develop a strategy or “action plan” for their next exam. This process provides students a way to earn bonus points while developing their communication skills and showcasing their writing skills in a convenient electronic forum. Thus students develop their own strategy and benefit by considering the collective wisdom of the top ten strategies posted on the course web site. Detailed instructions are provided below to implement an “Exam 2 strategy” assignment which provides students an action plan to better their next exam scores
Signatures of quantum chaos in rare-earth elements: II. Characterization of the energy eigenvalues and dipole moments of Ce I and Pr I
Using the relativistic configuration interaction Hartree–Fock method the energy
eigenvalues and dipole moments of Ce I, J = 4± and Pr I, J = 11/2±, both
members of the rare earth sequence, are examined for the presence of signatures
of quantum chaos, using the following spectral statistics: nearest neighbour
spacing, covariance of adjacent spacings, spectral rigidity, correlation-hole
method and χ2(ν) probability distribution
High Flux Femtosecond X-ray Emission from the Electron-Hose Instability in Laser Wakefield Accelerators
Bright and ultrashort duration X-ray pulses can be produced by through
betatron oscillations of electrons during Laser Wakefield Acceleration (LWFA).
Our experimental measurements using the \textsc{Hercules} laser system
demonstrate a dramatic increase in X-ray flux for interaction distances beyond
the depletion/dephasing lengths, where the initial electron bunch injected into
the first wake bucket catches up with the laser pulse front and the laser pulse
depletes. A transition from an LWFA regime to a beam-driven plasma wakefield
acceleration (PWFA) regime consequently occurs. The drive electron bunch is
susceptible to the electron-hose instability and rapidly develops large
amplitude oscillations in its tail, which leads to greatly enhanced X-ray
radiation emission. We measure the X-ray flux as a function of acceleration
length using a variable length gas cell. 3D particle-in-cell (PIC) simulations
using a Monte Carlo synchrotron X-ray emission algorithm elucidate the
time-dependent variations in the radiation emission processes.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev. Accel.
Beam
Multifractal analysis of selected rare-earth elements.
The multifractal formalism is applied to the energy eigenvalues of Ce I, CeII,
Nd II, SmI, SmII, and Tb I. The R´enyi dimensionsDq , mass exponents τ(q) and
f (α) spectra are calculated and used to characterize the eigenvalue spectra. It is
found that these elements show multi-scaling behaviour that can be accurately
modelled by simple multifractal recursive Cantor sets. The effect of unfolding
the spectra is also investigated
- …