bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monoline Regulations to Control the Systemic Risk Created by Investment Banks and GSEs
Authors: Jaffee Dwight M. 
Published: March 2009

Abstract
The paper offers a framework and a specific proposal for the re-regulation of key components of the U.S. financial system in the aftermath of the subprime mortgage crisis. It begins with a review of those aspects of the subprime crisis that required the large, observed government interventions, namely the feared bankruptcy of individual banks, insurers, and government sponsored enterprises with the potential to create a meltdown of the entire financial system. The paper then develops legislative responses that would make future systemic failures and bailouts of this magnitude highly unlikely. The paper's key analytic device is to distinguish two financial firm activities: (1) risky investment activities (hedge fund" division) capable of causing firm bankruptcy, and (2) market-making and related activities (infrastructure" division), the failure of which would have systemic implications. The goal of the proposed regulatory change is to ensure that the infrastructure division is bankruptcy remote and can operate on a stand-alone basis if necessary even when losses from the hedge fund division threaten the holding company's solvency.
Microstructure and mechanical properties of the AA6082 aluminium alloy with small additions of Sc and Zr
Authors: Vlach Martin , Smola Bohumil , Stulíková Ivana , Očenášek Vladivoj 
Published: March 2009

Abstract
The effect of Sc and Zr addition on microstructure and hardness development in a commercial as-cast and solution-treated (530 °C/45 min) AA6082 alloy was studied. The electrical resistivity decrease and hardness increase in the temperature range 180 – 300 °C are caused by precipitation of β′′ and/or β′ needles of the Mg – Si system. Precipitation and morphology changes of Al – Mn – Fe system phases in AA6082 and AA6082-ScZr alloys influence the resistivity significantly, but have a negligible effect on hardness. The initial hardness of Sc and Zr containing AA6082 alloys is higher mainly due to the presence of Al3(Sc, Zr) particles. This difference is less pronounced in the peak-hardening state. Natural ageing of solution-treated alloys influences microstructure development in both alloys when annealed subsequently up to 240 °C.
Mechanism and kinetics of the intermediary phase formation in Ti–Al and Ti–Al–Si systems during reactive sintering
Authors: Novák Pavel , Kubásek Jirí , Šerák Jan , Vojtěch Dalibor , Michalcová Alena 
Published: March 2009

AbstractIn this work, chemical reactions and phase transformations during reactive sintering of Ti – Al and Ti – Al – Si materials were investigated by differential thermal analysis. Kinetics and mechanism of the formation of intermediary phases are described on an experimental model system consisting of a bulk titanium sample exposed to molten aluminium or AlSi50 alloy. The results show that the reactive sintering is a reaction-controlled process in both systems. The reaction rate increases significantly with addition of silicon. According to the kinetics study, reactive sintering of TiAl36 and TiAl15Si15 alloys was carried out. TiAl15Si15 alloy was successfully sintered, while TiAl36 material showed extremely high porosity and presence of unreacted components.
Theoretical investigation of phase equilibria by the continuous displacement cluster variation method
Authors: Mohri Tetsuo 
Published: March 2009

Abstract
By employing the continuous displacement cluster variation method, order – disorder transition behavior of a two-dimensional square lattice is investigated. It is demonstrated that the distribution of displaced atoms around a Bravais lattice point continuously changes with temperature. The additional freedom of atomic displacement contributes to the entropy and thermal lattice expansion is confirmed. Finally, it is shown that the order – disorder transition temperature decreases as compared with the one by the conventional cluster variation method in which no local atomic displacements are allowed.
Vacancy–solute interaction in magnesium alloy WE54 during artificial ageing: a positron annihilation spectroscopy study
Authors: Moia Fabio , Calloni Alberto , Ferragut Rafael , Dupasquier Alfredo , Macchi Carlos Eugenio , Somoza Alberto , Nie Jian Feng 
Published: March 2009

Abstract
The vacancy – solute interaction during artificial ageing at 250 °C was studied in the commercial alloy WE54 by coincidence Doppler broadening of the positron annihilation radiation. The results show that in the initial state of ageing positron trapping is weak. Under these conditions, the faint signal comes predominantly from small Zr particles, with minor contributions from vacancy – Nd complexes. Positron trapping increases concomitantly with the formation of the ′- and 1-phases at the onset of precipitation hardening, and becomes very intense at later ageing stages when the 1-phase is formed. The chemical composition in contact with open-volume defects changes after 4 h of ageing with a progressive enrichment in Mg, concomitant with a hardness increase. There is evidence for a prevalence of Nd over Y up to 24 h of ageing and then a prevalence of Y over Nd for 96 h (Y/Nd 3) when the -phase is dominant.
Effects of prior homogenization treatments on microstructure development and mechanical properties of the extruded wrought magnesium alloy ZK60
Authors: Shahzad Muhammad , Janeček Miloš , Wagner Lothar 
Published: March 2009

Abstract
The wrought magnesium alloy ZK60 is extruded with and without prior homogenization treatments. Homogenization at 400 °C leads to effective dissolution of second phase particles whereas homogenization at 300 °C has little effect on them. These particles are broken down during the subsequent extrusion and play an important role in the dynamic recrystallization response of the alloy. Microstructure and mechanical properties after extruding with and without homogenization treatments are compared.
Recovery processes in magnesium alloy AX41 and AX41-12 vol.% C-fibre composite studied by dilatometry
Authors: Rudajevová Alexandra , Král Robert 
Published: March 2009

Abstract
The dilatation characteristics of pre-deformed AX41 magnesium alloy and AX41-12 vol.% C-fibre composite were determined in the temperature range 20 – 380 °C. Two fibre orientations for the composite were investigated: parallel and perpendicular to the axis sample. During the first thermal cycle after compression deformation, the recovery of the alloy and composite occurs in two steps. We observed the recovery of twins at low temperatures, and the recovery of dislocations at higher temperatures. The released plastic deformation is larger in composites with fibres perpendicular to the sample axis than in composites with fibres parallel to the sample axis. We analysed the deformation curves for the alloy and both composites.
Annealing effects after various thermo-mechanical treatments on microstructure and mechanical properties of the wrought magnesium alloy AZ80
Authors: Oo Min Zaw , Müller Julia , Janeček Miloš , Wagner Lothar 
Published: March 2009

Abstract
The magnesium alloy AZ80, received from Dead Sea magnesium in direct-chill cast condition was extruded at T = 350 °C using an extrusion ratio of ER = 12. The extruded bars were severe plastically deformed at 250 °C by utilizing thermo-mechanical treatments (TMT), either equal channel angular pressing (ECAP) or swaging.
While swaging led to similar grain refinements as observed after ECAP, yield stress and tensile strength values were by far superior in the swaged alloy. This result is explained by the unfavourable 45° texture component of the (0002) pole figure that develops during the massive shear deformation in ECAP. Unlike ECAP, the grain orientation after swaging is similar to the as-extruded condition. Annealing at elevated temperatures indicates very low thermal stability of microstructure and mechanical properties in the ECAP-ed alloy while both properties in the swaged microstructure are as stable as in the as-extruded reference.
FeAl-based alloys cast in an ultrasound field
Authors: Šíma Vladimír , Kratochvíl Petr , Kozelský Petr , Schindler Ivo , Hána Petr 
Published: March 2009

Abstract
An ultrasonic device was designed to fabricate relatively small (about 0.7 kg) vacuum chill castings of FeAl-based alloys with improved microstructure. The influence of ultrasound on the solidification microstructure of the Fe-40 at.% Al based castings was investigated. The subsequent hot-rolling of such an as-cast alloy was made using a special stainless steel bandage of the casting. This effectively prevents fraying and cracking caused by the thermal shock arising at the surface of the hot casting, when it comes in contact with a cold roller. The efficiency of ultrasonic vacuum casting, based on the influence of the acoustic cavitation on the solidification of the melt, is manifested by a refined microstructure of the prepared iron aluminides Fe-40 at.% Al with addition of C or Zr and B. First results of improved mechanical properties of these alloys are presented and discussed.
Strain-hardening behaviour of AZ31 magnesium alloys
Authors: Balík Jaroslav , Lukáč Pavel , Drozd Zdeněk , Kužel Radomír 
Published: March 2009

Abstract
The in-plane tensile behaviour of rolled sheets of the magnesium alloy AZ31 was investigated in both an H24 state and an aged state. Whereas the very high initial strain-hardening rate decreases monotonically with strain for the H24 samples, the annealed structure exhibits a striking increase in the strain-hardening rate. To explain this phenomenon, the occurrence of sessile dislocations associated with a secondary (pyramidal) slip is proposed. The absence of increasing hardening for the H24 state is supposed to be related to higher yield stresses (predeformations) within the grains of the polycrystalline aggregate.
Effect of annealing on microstructure and properties of twin-roll-cast Al–Mn alloys with different copper content
Authors: Slámová Margarita , Kubošová Andrea , Politello Julien , Cieslar Miroslav 
Published: March 2009

Abstract
Aluminium – manganese foils are used as fins in heat exchangers. Twin-roll casting reduces energy consumption, thus it is an environment-friendly casting procedure for these materials. Composition and processing variations affect foil properties and their optimization is a primary development goal. The results of a study of microstructure transformations occurring during the annealing of twin-roll-cast aluminium – manganese alloys with different copper content are reported and discussed. Microstructure and property evolution was monitored by resistometric measurements at – 196 °C during a slow stepwise heating up to 600 °C, microstructural analysis and hardness measurements. The copper content does not impact phase transformations but slightly modifies softening evolution with annealing temperature. Due to solid solution hardening, increasing copper content results in increased alloy hardness.
Hardening and softening in an Mg–Al–Ca matrix alloy reinforced with short graphite fibres
Authors: Trojanová Zuzanka , Lukáč Pavel 
Published: March 2009

Abstract
The mechanical properties of an AX41 magnesium alloy (4Al-1Ca-balance Mg; in wt.%) reinforced with Sigrafil C40 fibres were investigated. Compression tests were conducted at temperatures between 23 and 300 °C at a strain rate of 8.3 · 10– 5 s– 1. The yield stress and the maximum stress decrease with increasing testing temperature. The influence of the reinforcement on both characteristic stresses becomes weaker with increasing temperature. At higher temperatures, no significant work hardening was observed. The results indicate the occurrence of dynamic recovery. Possible hardening and softening mechanisms are discussed.
Austenite–martensite interfaces in strained foils of CuAlNi alloy
Authors: Ostapovets Andriy , Paidar Vaclav , Zarubova Niva 
Published: March 2009

AbstractGeometrical analysis of austenite – martensite interfaces in foils of a CuAlNi alloy is performed on the basis of the phenomenological theory of martensite. The interfaces in the foils of the CuAlNi alloy are faceted. In order to assess possible facet planes, lattice invariant deformation in the form of a simple shear is included into the phenomenological theory. The orientation ranges where the normals to the facet planes can lie were obtained. They agree with the experimentally observed facet planes.
Thresholds in creep of magnesium alloy AX41 composites reinforced with short fibers
Authors: Milička Karel , Dobeš Ferdinand 
Published: March 2009

Abstract
Creep behavior of four magnesium Mg-4Al-1Ca alloy-based composites reinforced with short alumina or carbon fibers was investigated at temperatures 423, 473, 523, and 623 K. The threshold creep behavior was observed in all composites as well as in the matrix alloy AX41. Both types of fibers strongly increase creep resistance of the composites. A stronger strengthening effect was observed in composites with alumina fibers. The applied stress dependences of the minimum creep rate of all investigated materials were well described by Garofalo' sinh relationship modified for threshold concept. Threshold stresses and their temperature dependences were evaluated from the stress dependences and discussed in detail from the viewpoint of contemporary knowledge of mechanisms governing the creep behavior of metal-matrix composites.
Effect of crystallization on the deformation behavior of a Zr-based bulk metallic glass
Authors: Lendvai János , Gubicza Jenő: , Lábár János L. , Kuli Zoltán 
Published: March 2009

Abstract
The crystallization process in a Zr-based bulk metallic glass with the composition Zr44Ti11Cu10Ni10Be25 was studied during isothermal annealing above the glass transition temperature at 682 K. Indentation creep tests were applied to study the effect of crystallization on the viscosity. It was found that the increase in viscosity during crystallization is primarily caused by the hard crystalline grains and secondarily by the change of the chemical composition of the remaining liquid phase. The deformation behavior at room temperature is studied by three-point bending tests. The strength of the specimens decreases significantly in the first step of the crystallization process.
Physical aspects of plastic deformation in Mg–Al alloys with Sr and Ca
Authors: Trojanová Zuzanka , Lukáč Pavel 
Published: March 2009

Abstract
Magnesium alloys of AJ (Mg – Al – Sr) and AX (Mg – Al – Ca) series were deformed at temperatures between room temperature and 300 °C. Stress relaxation tests were performed in order to reveal features of the thermally activated dislocation motion. The work hardening rate = d/d decreases with increasing stress and temperature. Analysis of the – plots revealed the hardening and softening mechanisms operating during the deformation. Internal and effective components of the applied stress have been estimated. Very high values of the internal stress estimated at lower temperatures decrease rapidly with increasing deformation temperature. The apparent activation volume decreases with increasing effective stress. The values of the activation volume as well as the activation enthalpy indicate that the main thermally activated process is most probably the glide of dislocations in non-compact planes.
Core structure of screw dislocations in hcp Ti: an ab initio DFT study
Authors: Tarrat Nathalie , Benoit Magali , Morillo Joseph 
Published: March 2009

Abstract
The core structure of screw dislocations in -Ti was studied in the cluster approach with ab initio DFT-GGA, and in both the cluster and quadrupole approaches with a recently highly optimized EAM central force potential. With the EAM potential we have shown that finite-size effects, in the cluster approach, are negligible down to the size studied in the ab initio DFT calculations that have shown unambiguously a preferential prismatic core spreading for the dislocation. Our results are in agreement with previously published approximated calculations using empirical or semi-empirical interaction models: only approximated interaction models, taking explicitly into account the covalent directional bonding of the d electrons, can properly account for the preferential prismatic core spreading against the basal one; and empirical interaction models without angular force components are inadequate. Interestingly, at first sight, the relaxed core structures (basal or prismatic) obtained with empirical or semi-empirical interaction models are almost identical to the ones obtained with the ab initio DFT calculations.
Experimental study of particle concentration fluctuations in a turbulent steady flow
Authors: Cierco François-Xavier , Naaim Mohamed , Naaim-Bouvet Florence 
Published: March 2009

AbstractSpecific features of the physics of blown sand and PVC particles were investigated in wind-tunnel experiments. The fluctuations in particle concentration over time were derived from image processing of high-speed films (500 Hz). Spectral analysis of these time series showed a slowly decreasing slope within a frequency range that could be larger than the inertial sub-range of the free stream. A specific transport regime also appears in the lower part of the flow for frequencies less than 10 Hz. The role of turbulence in the generation of this regime is discussed using a simple theoretical model able to describe the aerodynamic behavior of a particle.
Spatial variability of new snow amounts derived from a dense network of Alpine automatic stations
Authors: Egli Luca 
Published: March 2009

AbstractSince 1996, a dense network of Alpine automatic weather and snow-measurement (Interkantonales Mess- und Informationssystem (IMIS)) stations has been in operational use for local and regional avalanche warning. The measurements of the IMIS stations are assumed to be representative for spatially extended regions around the measuring sites for applications in avalanche risk management. In this study, the regional representativeness of these stations with regard to the daily amount of new snow is investigated. The results show that the amount of daily new snow is spatially correlated in a range of ∼5–55 km. Regarding simultaneous observations of daily new snow measurements, which are ∼5–10 km apart, the probability of detection (POD) is given as 0.5±0.03. In this paper, the POD of an automatic warning network is introduced as an indicator of the representativeness of point measurement information for avalanche warning applications. The results of this study may mark a reference value for verification of spatially distributed Alpine meteorological models which evaluate the amount of daily new snow in the Swiss Alps.
Glacier thickening and decay analysis from 50 years of glaciological observations performed on Glacier d’Argentière, Mont Blanc area, France
Authors: Vincent C. , Soruco A. , Six D. , Le Meur E. 
Published: March 2009

AbstractNumerous glaciological data have been obtained from measurements carried out on Glacier d’Argentière, Mont Blanc area, France, since the beginning of the 20th century. Moreover, data on annual mass balance, ice-flow velocity, thickness variation and length fluctuation have been obtained from yearly measurements performed since 1975. This dataset provides an excellent opportunity to analyze the relationships between surface mass balance and dynamic response over time periods during which net mass balance changed from positive to negative. Following a positive specific-net-balance period between 1960 and 1981, the ablation zone experienced a large increase in thickness and ice-flow velocities. Conversely, the highly negative specific-net-balance period since 1982 has led to strong thinning, deceleration and retreat of the tongue. The response of these observed dynamics to surface mass balance is analyzed from ice-flux calculations performed on three transverse cross-sections. Our results reveal that the ice fluxes are largely accommodated by ice-flow velocities. Velocity fluctuations are synchronous over the entire area studied. In the largest part of the glacier, no compressing/extending flow change has been observed over the last 30 years and thickness changes are solely driven by surface mass-balance changes. However, on the tongue of the glacier, thickness changes do not depend on surface mass balance but are mainly driven by changes in the longitudinal strain rate.
Meteorological controls on snow and ice ablation for two contrasting months on Glacier de Saint-Sorlin, France
Authors: Six D. , Wagnon P. , Sicart J.E. , Vincent C. 
Published: March 2009

AbstractThe influence of meteorological variables on snow/ice melting has been analyzed for two very contrasting months, in summer 2006, on Glacier de Saint-Sorlin, French Alps. July 2006 was the warmest July since 1950, and August 2006 was the coldest August since 1979. The total energy available for melting was just over half as much in August as in July, due to a sharp decrease in net shortwave radiation and in turbulent flux. This decrease of net shortwave radiation was mainly controlled by a strong increase in albedo responsible for an increase of reflected shortwave radiation, as well as by a reduction in incident shortwave radiation. During the two months, net longwave radiation remained almost unchanged. The mass balance computed from energy-balance modelling or with a degree-day approach was in good agreement with measured mass balance. Differences were attributed to space and time surface aspect variations which mainly controlled the observed mass balance.
Best possible estimation of mass balance combining glaciological and geodetic methods
Authors: Thibert E. , Vincent C. 
Published: March 2009

AbstractVariance analysis of the long time series of mass balances recorded on Glacier de Sarennes (45°07’ N, 6°07’ E) France, since 1949 shows that the variability can be separated linearly in two spatial and temporal terms. Annual balances deviate from their mean values over the period of record by an annual amount that is uniform over the glacier. Annual balances at each stake are therefore highly correlated, and sampling at a single site would be acceptable to record the annual deviation. A result of the linear character of the variance is the possibility of obtaining a systematic error-free estimate of the annual glacier-total budget by combining the mean annual balance obtained from photogrammetry and the annual deviation obtained from the variance analysis, rather than using the traditional area integration of balances at each stake.
On the role of subsurface heat conduction in glacier energy-balance modelling
Authors: Pellicciotti Francesca , Carenzo Marco , Helbing Jakob , Rimkus Stefan , Burlando Paolo 
Published: March 2009

AbstractWe discuss the inclusion of the subsurface heat-conduction flux into the calculation of the energy balance and ablation at the glacier–atmosphere interface. Data from automatic weather stations are used to force an energy-balance model at several locations on alpine glaciers and at one site in the dry Andes of central Chile. The heat-conduction flux is computed using a two-layer scheme, assuming that 36% of the net shortwave radiation is absorbed by the surface layer and that the rest penetrates into the snowpack. We compare simulations conducted with and without subsurface heat flux. Results show that assuming a surface temperature of zero degrees leads to a larger overestimation of melt at the sites in the accumulation area (10.4–13.3%) than in the ablation area (0.5–2.8%), due to lower air temperatures and the presence of snow. The difference between simulations with and without heat conduction is also high at the beginning and end of the ablation season (up to 29% for the first 15 days of the season), when air temperatures are lower and snow covers the glacier surface, while they are of little importance during periods of sustained melt at all the locations investigated.