A Simple Method for the Estimation of the Axial Dispersion Coefficient in Gas Flow

A simple method which is suitable for determining with reasonable precision the parameters of gas flow system has been proposed. An inverse boundary-value problem is considered. The model of gas flow with the Danckwert’s boundary conditions in a real measurement system has been analyzed and solved. The tracer technique was applied to determine axial dispersion coefficient of gas phase and Pèclet number. These parameters are commonly used to characterize the flow behavior of fluids. Axial dispersion coefficients were estimated by comparing model solution with recorded TCD signal (an inverse problem as a method for model parameter estimation) employing the Laplace transform technique. The Gaver-Stehfest algorithm for the solution of the mathematical model has been applied. The proposed model of gas show a good agreement with the experimental data. The obtained results show that under operation conditions in the studied system the flow behaviour is neither plug flow nor perfect mixing. The described method is very fast in both experimental and computational part. Simple and errorless derivation of sophisticated model formulas has been possible by application of the Computer Algebra System-type program. The program also simplifies computations. Mathematical manipulations and computations were performed using program Maple®

Relativistic Nuclear Energy Density Functionals: Mean-Field and Beyond

Relativistic energy density functionals (EDF) have become a standard tool for nuclear structure calculations, providing a complete and accurate, global description of nuclear ground states and collective excitations. Guided by the medium dependence of the microscopic nucleon self-energies in nuclear matter, semi-empirical functionals have been adjusted to the nuclear matter equation of state and to bulk properties of finite nuclei, and applied to studies of arbitrarily heavy nuclei, exotic nuclei far from stability, and even systems at the nucleon drip-lines. REDF-based structure models have also been developed that go beyond the static mean-field approximation, and include collective correlations related to the restoration of broken symmetries and to fluctuations of collective variables. These models are employed in analyses of structure phenomena related to shell evolution, including detailed predictions of excitation spectra and electromagnetic transition rates.Comment: To be published in Progress in Particle and Nuclear Physic

Large-Scale Self-Consistent Nuclear Mass Calculations

The program of systematic large-scale self-consistent nuclear mass calculations that is based on the nuclear density functional theory represents a rich scientific agenda that is closely aligned with the main research directions in modern nuclear structure and astrophysics, especially the radioactive nuclear beam physics. The quest for the microscopic understanding of the phenomenon of nuclear binding represents, in fact, a number of fundamental and crucial questions of the quantum many-body problem, including the proper treatment of correlations and dynamics in the presence of symmetry breaking. Recent advances and open problems in the field of nuclear mass calculations are presented and discussed.Comment: 21 pages, 5 figures, submitted to International Journal of Mass Spectrometr

Quadrupole collectivity in Ca 42 from low-energy Coulomb excitation with AGATA

A Coulomb-excitation experiment to study electromagnetic properties of Ca42 was performed using a 170-MeV calcium beam from the TANDEM XPU facility at INFN Laboratori Nazionali di Legnaro. γ rays from excited states in Ca42 were measured with the AGATA spectrometer. The magnitudes and relative signs of ten E2 matrix elements coupling six low-lying states in Ca42, including the diagonal E2 matrix elements of 21+ and 22+ states, were determined using the least-squares code gosia. The obtained set of reduced E2 matrix elements was analyzed using the quadrupole sum rule method and yielded overall quadrupole deformation for 01,2+ and 21,2+ states, as well as triaxiality for 01,2+ states, establishing the coexistence of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in Ca42. The experimental results were compared with the state-of-the-art large-scale shell-model and beyond-mean-field calculations, which reproduce well the general picture of shape coexistence in Ca42

Superdeformed and Triaxial States in Ca 42

Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in ^{42}Ca were determined from E2 matrix elements measured in the first low-energy Coulomb excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 0_{2}^{+} has been obtained and the role of triaxiality in the A∼40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time

Reducing the development gaps between regions in Poland with the use of European Union funds

The paper evaluates the processes of regional income convergence in Poland. This new research approach involves an attempt to assess the process of convergence from the point of view of development gaps. Six key development gaps were considered in the region of Eastern Poland, which is a singular case, significantly different from other regions. A dynamic panel data model was applied to investigate the impact of EU funds on the progress made towards closing these development gaps. Among the analysed development gaps, only the structural gap was not reduced in the period 2004–2015. Studies have also revealed the different impact of structural funds on each category of development gaps (a positive impact on reducing the regional transport accessibility gap and the investment gap, but negative – on reducing the innovation gap). Research has suggested the need for a change in the structure of using EU funds in the period 2014–2020 to favour stronger support for entrepreneurship and the creation of new jobs. Greater stimulation of the economic structure of peripheral regions has been proposed as the prerequisite for the future reduction in the discrepancies between regions and for the intensification of convergence. First published online 2 April 201

Simultaneous γ-ray and electron spectroscopy of 182,184,186Hg isotopes

Background: The mercury isotopes around N=104 are a well-known example of nuclei exhibiting shape coexistence. Mixing of configurations can be studied by measuring the monopole strength ρ2(E0), however, currently the experimental information is scarce and lacks precision, especially for the Iπ→Iπ (I≠0) transitions. Purpose: The goals of this study were to increase the precision of the known branching ratios and internal conversion coefficients, to increase the amount of available information regarding excited states in Hg182,184,186, and to interpret the results in the framework of shape coexistence using different models. Method: The low-energy structures in Hg182,184,186 were populated in the β decay of Tl182,184,186, produced at ISOLDE, CERN and purified by laser ionization and mass separation. The γ-ray and internal conversion electron events were detected by five germanium clover detectors and a segmented silicon detector, respectively, and correlated in time to build decay schemes. Results: In total, 193, 178, and 156 transitions, including 144, 140, and 108 observed for the first time in a β-decay experiment, were assigned to Hg182,184,186, respectively. Internal conversion coefficients were determined for 23 transitions, out of which 12 had an E0 component. Extracted branching ratios allowed the sign of the interference term in Hg182 as well as ρ2(E0;02+→01+) and B(E2;02+→21+) in Hg184 to be determined. By means of electron-electron coincidences, the 03+ state was identified in Hg184. The experimental results were qualitatively reproduced by five theoretical approaches, the interacting boson model with configuration mixing with two different parametrizations, the general Bohr Hamiltonian, the beyond mean-field model, and the symmetry-conserving configuration-mixing model. However, a quantitative description is lacking. Conclusions: The presence of shape coexistence in neutron-deficient mercury isotopes was confirmed and evidence for the phenomenon existing at higher energies was found. The new experimental results provide important spectroscopic input for future Coulomb excitation studies

The effect of calcination temperature on properties and activity of Cu/ZnO/Al_2O_3catalysts

The paper presents the results of the investigation on the influence of calcination temperature of Cu-Zn-Al catalyst precursor, on physicochemical properties and catalytic activity for water gas shift reaction. A model precursor of chemical composition corresponding with a typical commercial catalyst and prepared by coprecipitation method was studied. It has been shown that the temperature of calcination step determines the surface properties of the final catalyst, the active phase dispersion, and thus significantly affects the catalytic activity