8,217 research outputs found
On the Equivalence of the Digital Waveguide and Finite Difference Time Domain Schemes
It is known that the digital waveguide (DW) method for solving the wave
equation numerically on a grid can be manipulated into the form of the standard
finite-difference time-domain (FDTD) method (also known as the ``leapfrog''
recursion). This paper derives a simple rule for going in the other direction,
that is, converting the state variables of the FDTD recursion to corresponding
wave variables in a DW simulation. Since boundary conditions and initial values
are more intuitively transparent in the DW formulation, the simple means of
converting back and forth can be useful in initializing and constructing
boundaries for FDTD simulations.Comment: v1: 6 pages; v2: 7 pages, generally more polished, more examples,
expanded discussion; v3: 15 pages, added state space formulation, analysis of
inputs and boundary conditions, translation of passive boundary conditions;
v4: various typos fixe
On the generation of pseudo-random numbers from several non-uniform distributions
Methods for generating pseudorandom numbers from nonuniform statistical distribution
Golden Arm: A Probabilistic Study of Dice Control in Craps
This paper calculates how much control a craps shooter must possess on dice outcomes to eliminate the house advantage. A golden arm is someone who has dice control (or a rhythm roller or dice influencer). There are various strategies for dice control in craps. We discuss several possibilities of dice control that would result in several different mathematical models of control. We do not assert whether dice control is possible or not (there is a lack of published evidence). However, after studying casino-legal methods described by dice-control advocates, we can see only one realistic mathematical model that describes the resulting possible dice control, that in which the four faces on a rotating (horizontal) axis are favored. This is the model that we analyze in this paper
Transductions Computed by One-Dimensional Cellular Automata
Cellular automata are investigated towards their ability to compute
transductions, that is, to transform inputs into outputs. The families of
transductions computed are classified with regard to the time allowed to
process the input and to compute the output. Since there is a particular
interest in fast transductions, we mainly focus on the time complexities real
time and linear time. We first investigate the computational capabilities of
cellular automaton transducers by comparing them to iterative array
transducers, that is, we compare parallel input/output mode to sequential
input/output mode of massively parallel machines. By direct simulations, it
turns out that the parallel mode is not weaker than the sequential one.
Moreover, with regard to certain time complexities cellular automaton
transducers are even more powerful than iterative arrays. In the second part of
the paper, the model in question is compared with the sequential devices
single-valued finite state transducers and deterministic pushdown transducers.
It turns out that both models can be simulated by cellular automaton
transducers faster than by iterative array transducers.Comment: In Proceedings AUTOMATA&JAC 2012, arXiv:1208.249
Stellar Populations and Ages of M82 Super Star Clusters
We present high signal-to-noise optical spectra of two luminous super star
clusters in the starburst galaxy M82. The data for cluster F and the nearby,
highly reddened cluster L were obtained with the William Herschel Telescope
(WHT) at a resolution of 1.6A. The blue spectrum (3250-5540A) of cluster F
shows features typical of mid-B stars. The red spectra (5730-8790A) of clusters
F and L show the Ca II triplet and numerous F and G-type absorption features.
Strong Ca II and Na I interstellar absorption lines arising in M82 are also
detected, and the 6283A diffuse interstellar band appears to be present. The
quality of the WHT spectra allows us to considerably improve previous age
estimates for cluster F. By comparing the blue spectrum with theoretical model
cluster spectra using the PEGASE spectral synthesis code (Fioc &
Rocca-Volmerange 1997), we derive an age of 60+/-20 Myr. The strength of the Ca
II triplet is also in accord with this age. Cluster L appears to have a similar
age, although this is much less certain. The measured radial velocities for the
two clusters differ substantially, indicating that they are located in
different regions of the M82 disk. Cluster F appears to be deep in M82,
slightly beyond the main starburst region while the highly obscured cluster L
lies near the outer edges of the disk. We derive an absolute V magnitude of
-16.5 for F indicating that it is an extremely massive cluster. The presence of
such a luminous super star cluster suggests that the M82 starburst experienced
an episode of intense star formation approximately 60 Myr ago.Comment: 10 pages and 5 figures for publication in MNRA
Economical technique for fragmentation testing
Automatic rifle was modified for remote, single-shot use. To simulate statistically--determined fragment size from rocket-motor casing blunt-nosed bullet was made of same alloy. Cartridge was loaded with enough powder to make bullet reach target at same estimated velocity as shrapnel from rocket casing
Gasoline Taxes in Georgia
This report describes and compares Georgia's fuel tax with other states and evaluates it as a long-term dedicated revenue source for highway funding in the state. FRC Report 12
Understanding linear measure
This article provides strategies for enhancing tasks to offer students better opportunities to develop conceptual understanding of length measurement. Teachers are offered strategies that help move instruction beyond procedures
Development and evaluation of a fault-tolerant multiprocessor (FTMP) computer. Volume 4: FTMP executive summary
The FTMP architecture is a high reliability computer concept modeled after a homogeneous multiprocessor architecture. Elements of the FTMP are operated in tight synchronism with one another and hardware fault-detection and fault-masking is provided which is transparent to the software. Operating system design and user software design is thus greatly simplified. Performance of the FTMP is also comparable to that of a simplex equivalent due to the efficiency of fault handling hardware. The FTMP project constructed an engineering module of the FTMP, programmed the machine and extensively tested the architecture through fault injection and other stress testing. This testing confirmed the soundness of the FTMP concepts
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