Monte Carlo Integration with Subtraction

This paper investigates a class of algorithms for numerical integration of a function in d dimensions over a compact domain by Monte Carlo methods. We construct a histogram approximation to the function using a partition of the integration domain into a set of bins specified by some parameters. We then consider two adaptations; the first is to subtract the histogram approximation, whose integral we may easily evaluate explicitly, from the function and integrate the difference using Monte Carlo; the second is to modify the bin parameters in order to make the variance of the Monte Carlo estimate of the integral the same for all bins. This allows us to use Student's t-test as a trigger for rebinning, which we claim is more stable than the \chi-squared test that is commonly used for this purpose. We provide a program that we have used to study the algorithm for the case where the histogram is represented as a product of one-dimensional histograms. We discuss the assumptions and approximations made, as well as giving a pedagogical discussion of the myriad ways in which the results of any such Monte Carlo integration program can be misleading.Comment: Code PANIC included as a set of ancillary file

Erosion of metals by multiple impacts with water

Investigation determines - relation between impact velocity and minimum number of impacts producing visible erosion, relation between high frequency fatigue stresses and number of cycles to failure, water-hammer stresses relation to high frequency endurance limit, erosion rate as exposure time function, and correlates experimental data with recent theory

Postcard Written by Rudy A. Bigda to the Bryant College Service Club Dated June 23, 1943

[Transcription begins] R. A. Bigda 2098 QM Trk (Am) A.P.O. 402 Nashville, Tennessee June 23, 1943 [Postmark date] Bryant Service Club Bryant College Providence, Rhode Island It certainly is quite charming to receive gifts thru [sic] the generosity and good fellowship of students that I have never seen and it is with deep appreciation and gratitude that I acknowledge the receipt of your most welcome gift. As you probably recognize I am now a 2nd Lt. and have traveled quite extensively in the past two months with different organizations. In fact I have been in about 18 states and at least 12 or 15 different posts. It surprises me to think of the long way your gift had to come- but nevertheless it finally reached me - even out in the world on maneuvers – which makes the thoughtfulness on your part doubly surprising. There isn’t much I can say except to thank you as a group + as fellow students and to ask you to keep up your good work on the home front – we’ll take care of the field. Sincerely, R. A. Bigd

Experimental and analytical investigations on multiple liquid impact erosion

Experimental and analytical studies of multiple liquid impact erosion of aluminum and stainless stee

Relative Price Volatility Under Sudden Stops: The Relevance of Balance Sheet Effects

Sudden Stops are associated with increased volatility in relative prices. We introduce a model based on information acquisition to rationalize this increased volatility. An empirical analysis of the conditional variance of the wholesale price to consumer price ratio using panel ARCH techniques confirms the relevance of Sudden Stops and potential balance-sheet effects as key determinants of relative-price volatility, where balance-sheet effects are captured by the interaction of a proxy for potential changes in the real exchange rate (linked to the degree of external leverage of the absorption of tradable goods) and a measure of domestic liability dollarization.

Spectral components at visual and infrared wavelengths in active galactic nuclei

Aperture-dependent infrared photometry of active galactic nuclei are presented which illustrate the importance of eliminating starlight of the galaxy in order to obtain the intrinsic spectral distribution of the active nuclei. Separate components of emission are required to explain the infrared emission with a spectral index of alpha approx = 2 and the typical visual-ultraviolet continuum with alpha approx = 0.3 (where F(nu) varies as nu(sup-alpha). Present evidence does not allow unique determination of the appropriate mechanisms, but the characteristics of each are discussed

Cavitation damage in liquid metals technical progress report, 1 jan. - 31 mar. 1965

Temperature effect on rate of cavitation damage of 316 stainless steel in pure liquid sodium at temperatures up to 1500 deg

Transport analysis of K+ production in proton-nucleus reactions

The production of $K^+$ mesons in proton-nucleus collisions from 1.0 to 2.3 GeV is analyzed with respect to one-step nucleon-nucleon $(NN\to N Y K^+$) and two-step $\Delta$-nucleon $(\Delta N \to K^+ Y N$) or pion-nucleon $(\pi N \to K^+ Y$) production channels on the basis of a coupled-channel transport approach (CBUU) including the kaon final-state-interactions (FSI). Momentum-dependent potentials for the nucleon, hyperon and kaon in the final state are included as well as $K^+$ elastic rescattering in the target nucleus. The transport calculations are compared to the experimental $K^+$ spectra taken at COSY-J\"ulich. Our systematic analysis of $K^+$ spectra from $^{12}C$, $^{63}Cu$, $^{107}Ag$ and $^{197}Au$ targets as well as their momentum differential ratios gives a repulsive $K^+$ potential of $20\pm 5$ MeV at normal nuclear matter density.Comment: 7 pages, 5 figures, submitted to Eur. Phys. J.