Gas gun shock experiments with single-pulse x-ray phase contrast imaging and diffraction at the Advanced Photon Source

The highly transient nature of shock loading and pronounced microstructure effects on dynamic materials response call for {\it in situ}, temporally and spatially resolved, x-ray-based diagnostics. Third-generation synchrotron x-ray sources are advantageous for x-ray phase contrast imaging (PCI) and diffraction under dynamic loading, due to their high photon energy, high photon fluxes, high coherency, and high pulse repetition rates. The feasibility of bulk-scale gas gun shock experiments with dynamic x-ray PCI and diffraction measurements was investigated at the beamline 32ID-B of the Advanced Photon Source. The x-ray beam characteristics, experimental setup, x-ray diagnostics, and static and dynamic test results are described. We demonstrate ultrafast, multiframe, single-pulse PCI measurements with unprecedented temporal ($<$100 ps) and spatial ($\sim$2 $\mu$m) resolutions for bulk-scale shock experiments, as well as single-pulse dynamic Laue diffraction. The results not only substantiate the potential of synchrotron-based experiments for addressing a variety of shock physics problems, but also allow us to identify the technical challenges related to image detection, x-ray source, and dynamic loading

Recent Labour Market Trends in the Visegrad Group Countries

The large declines in the Slovak and Czech employment appeared because the countries' GDPs grew smaller while real wages grew bigger. Shorter working hours and limitations on labour productivity that the two countries introduced could not reverse the unfavourable employment trends that occurred during economic downturn.Duże spadki zatrudnienia w Słowacji i Czechach były związane ze słabym wzrostem PKB i silnym wzrostem płac realnych. Redukcje czasu pracy i wydajności pracy nie były w stanie odwrócić niekorzystnych tendencji w zatrudnieniu

Hammerhead, an ultrahigh resolution ePix camera for wavelength-dispersive spectrometers

Wavelength-dispersive spectrometers (WDS) are often used in synchrotron and FEL applications where high energy resolution (in the order of eV) is important. Increasing WDS energy resolution requires increasing spatial resolution of the detectors in the dispersion direction. The common approaches with strip detectors or small pixel detectors are not ideal. We present a novel approach, with a sensor using rectangular pixels with a high aspect ratio (between strips and pixels, further called "strixels"), and strixel redistribution to match the square pixel arrays of typical ASICs while avoiding the considerable effort of redesigning ASICs. This results in a sensor area of 17.4 mm x 77 mm, with a fine pitch of 25 $\mu$m in the horizontal direction resulting in 3072 columns and 176 rows. The sensors use ePix100 readout ASICs, leveraging their low noise (43 e$^-$, or 180 eV rms). We present results obtained with a Hammerhead ePix100 camera, showing that the small pitch (25 $\mu$m) in the dispersion direction maximizes performance for both high and low photon occupancies, resulting in optimal WDS energy resolution. The low noise level at high photon occupancy allows precise photon counting, while at low occupancy, both the energy and the subpixel position can be reconstructed for every photon, allowing an ultrahigh resolution (in the order of 1 $\mu$m) in the dispersion direction and rejection of scattered beam and harmonics. Using strixel sensors with redistribution and flip-chip bonding to standard ePix readout ASICs results in ultrahigh position resolution ($\sim$1 $\mu$m) and low noise in WDS applications, leveraging the advantages of hybrid pixel detectors (high production yield, good availability, relatively inexpensive) while minimizing development complexity through sharing the ASIC, hardware, software and DAQ development with existing versions of ePix cameras.Comment: 8 pages, 6 figure

Characterizing the berthing load environment of the Seattle ferry teminal, Bremerton slip

Thesis (M.S.) University of Alaska Fairbanks, 2012This manuscript characterizes and presents design recommendations for berthing demands on ferry landing structures. There is a lack of research focused on the berthing load demand imparted by ferry class vessels, therefore the load criteria used for design is often based on a number of assumptions. This study involved a one-year field study of the structural load environment of wingwalls at the Bremerton Slip of the Seattle Ferry Terminal, located in Elliott Bay adjacent to Seattle, Washington. Measurements of marine fender displacement, vessel approach distance with respect to time, and. pile strain were used to determine berthing demands. Berthing event parameters were characterized using the Python programming language, compiled, and analyzed statistically. Probability theory was used to provide design value recommendations for berthing energy, force, approach velocity, berthing factor, and berthing coefficient. This study presents a number of engineering design aids intended to quantify the berthing load environment of wingwalls in the Washington State Ferry System

Thermally-induced expansion in the 8 GeV/c π−\pi^- + 197^{197}Au reaction

Fragment kinetic energy spectra for reactions induced by 8.0 GeV/c $\rm{\pi^-}$ beams incident on a $\rm{^{197}}$Au target have been analyzed in order to deduce the possible existence and influence of thermal expansion. The average fragment kinetic energies are observed to increase systematically with fragment charge but are nearly independent of excitation energy. Comparison of the data with statistical multifragmentation models indicates the onset of extra collective thermal expansion near an excitation energy of E*/A $\rm{\approx}$ 5 MeV. However, this effect is weak relative to the radial expansion observed in heavy-ion-induced reactions, consistent with the interpretation that the latter expansion may be driven primarily by dynamical effects such as compression/decompression.Comment: 12 pages including 4 postscript figure

Analyzing Powers for Complex Fragments Formed in the 200 MeV pol.p + Ag Reaction

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

The Okun Misery Index in the European Union Countries from 2000 to 2009

The study is composed of four main parts and a summary. The first part, introduction, discusses various measures of the economic system's efficiency that are used in practice. Part two emphasises that the GDP per capita according to purchasing power parity still remains the most popular among those measures. Further, it presents the ranking of the European Union countries taking that measure into account, the research period being 1999-2009. Part three points out that it is also the level of poverty (misery) that determines the economic system's efficiency. That level can be measured by means of various indicators, among others, the so called HPI-2 index calculated by the UN. It will be the Okun misery index, however, computed as the sum of inflation and unemployment rates that will be presented as an alternative being of interest from the macroeconomic point of view. The ranking of the European Union member states according to that measure in the 2000-2004 and 2005-2009 periods will be provided in part four. The article will end in a summary containing synthetic conclusions drawn from earlier observations.Opracowanie składa się z czterech części zasadniczych i podsumowania. W punkcie pierwszym omówiono różnorodne mierniki sprawności systemu gospodarczego wykorzystywane w praktyce. W części drugiej podkreślono, iż nadal najpopularniejszym z nich jest PKB per capita według parytetu siły nabywczej. Zgodnie z tym miernikiem przedstawiono ranking państw Unii Europejskiej w latach 1999-2009. W punkcie trzecim podkreślono, że o sprawności systemu gospodarczego decyduje także poziom ubóstwa. Może być on mierzony różnymi wskaźnikami, m.in. tzw. indeksem HPI-2 obliczanym przez ONZ. Jako ciekawą z makroekonomicznego punktu widzenia alternatywę ukazano jednak miarę wskaźnika ubóstwa Okuna obliczanego poprzez zsumowanie stopy inflacji i stopy bezrobocia. Ranking państw Unii Europejskiej według tej miary w okresach 2000-2004 oraz 2005-2009 zaprezentowano w części czwartej. Całość zamknięto podsumowaniem, w którym zawarto syntetyczne wnioski z przeprowadzonych obserwacji