Inverse medium problem for a singular contrast

We consider an inverse medium problem in two- and three-dimensional cases. Namely, we investigate the problem of reconstruction of unknown compactly supported refractive index (contrast) from L-2 with a fixed positive wave number. The proof is based on the new estimates for the Green-Faddeev function in L-infinity space. The main goal of this work is to prove a uniqueness result in the two- and three-dimensional cases and to discuss some possible constructive methods for solving the problem. Finally, we present some numerical examples to demonstrate the results in two dimensions. Published under license by AIP Publishing.Peer reviewe

adiabatic versus nonadiabatic dressed-state dynamics

We discuss how a recent pump-probe study [Kelkensberg et al., Phys. Rev. Lett. 103, 123005 (2009)] of the dissociative ionization of H2, under the combined effect of a single extreme ultraviolet attosecond pulse and an intense near- infrared pulse, actually represents a transition-state spectroscopy of the strong-field dissociation step, i.e., of the (probe-pulse-)dressed H2+ molecular ion. The way the dissociation dynamics is influenced by the duration of the near-infrared probe pulse, and by the time delay between the two pulses, is discussed in terms of adiabatic versus nonadiabatic preparation and transport of time-parametrized Floquet resonances associated with the dissociating molecular ion. Under a long probe pulse, the field-free vibrational states of the initial wave packet are transported, in a one-to-one manner, onto the Floquet resonances defined by the field intensity of the probe pulse and propagated adiabatically under the pulse. As the probe pulse duration shortens, nonadiabatic transitions between the Floquet resonances become important and manifest themselves in two respects: first, as a vibrational shake-up effect occurring near the peak of the short pulse, and second, through strong interference patterns in the fragment's kinetic energy spectrum, viewed as a function of the time delay between the pump and the probe pulses

Hydration of copper(II) amino acids complexes

© 2017 Wiley Periodicals, Inc. Hydration of the copper(II) bis-complexes with glycine, serine, lysine, and aspartic acid was studied by DFT and MD simulation methods. The distances between copper(II) and water molecules in the 1st and 2nd coordination shells, the average number of water molecules and their mean residence times in the hydration shells were calculated. Good agreement was observed between the values obtained and those found by DFT and NMR relaxation methods. Influence of the functional groups of the ligands and the cis-trans isomerism of the complexes on the structural and dynamical parameters of the hydration shells was displayed and explained. Analysis of the MD trajectories reveals the competition for a copper(II) axial position between water molecules or water molecules and the functional chain groups of the ligands and confirms the suggestion on the pentacoordination of copper(II) in such complexes. MD simulations show that only one axial position of Cu(II) is basically occupied at each time step while in average the coordination number more than 5 is observed

The influence of changes in the project on the reliability of heat power systems during construction and installation works

However, during the construction and reconstruction of existing heat networks, cases that lead to unstable operation of newly laid or replaced areas arise. An important task is to minimize the reasons that can cause damage to replaced areas. Factors that negatively affect the reliability include: laying pipelines without design documentation, non-compliance of the regulatory requirements for their laying by installation organizations. The assumptions of design engineers developing the project and installers laying the heating main can lead to negative consequences, including a decrease in the reliability of the facilities functioning. Physical deterioration, coupled with the above factors, leads to a large number of failures of heat networks. Breakthroughs reduce the reliability of the entire heat supply system, worsen the quality of the supplied coolant and lead to an increase in the cost of maintenance of heat networks by operating organizations. The paper considers the influence of changes in the project during the construction and installation works on the reliability of the heat supply system. Document type: Articl

Development of the Northern Sea Route on the Route Murmansk-Vladivostok-Shanghai (China)

The paper considers the development of the Northern Sea Route (NSR) in modern Russia and China. The analysis of cargo turnover and the advantages of the NSR is carried out. The importance of the nuclear icebreaker fleet in the development of the NSR is determined and specified. The route is currently considered as transcontinental and it is planned to become part of the “Silk Road”. It belongs to the number of Russian national projects. As an international transit highway, the Northern Sea Route has a huge potential for international cooperation and development of the North and East of Russia. The cluster-modular approach in the organization of NSR is considered. © 2022 The Authors. Published by ELSEVIER B.V

Superaerophobic graphene nano-hills for direct hydrazine fuel cells

Hydrazine fuel-cell technology holds great promise for clean energy, not only because of the greater energy density of hydrazine compared to hydrogen but also due to its safer handling owing to its liquid state. However, current technologies involve the use of precious metals (such as platinum) for hydrazine oxidation, which hinders the further application of hydrazine fuel-cell technologies. In addition, little attention has been devoted to the management of gas, which tends to become stuck on the surface of the electrode, producing overall poor electrode efficiencies. In this study, we utilized a nano-hill morphology of vertical graphene, which efficiently resolves the issue of the accumulation of gas bubbles on the electrode surface by providing a nano-rough-edged surface that acts as a superaerophobic electrode. The growth of the vertical graphene nano-hills was achieved and optimized by a scalable plasma-enhanced chemical vapor deposition method. The resulting metal-free graphene-based electrode showed the lowest onset potential (-0.42 V vs saturated calomel electrode) and the highest current density of all the carbon-based materials reported previously for hydrazine oxidation

A quantitative theory-versus-experiment comparison for the intense laser dissociation of H2+

A detailed theory-versus-experiment comparison is worked out for H$_2^+$ intense laser dissociation, based on angularly resolved photodissociation spectra recently recorded in H.Figger's group. As opposite to other experimental setups, it is an electric discharge (and not an optical excitation) that prepares the molecular ion, with the advantage for the theoretical approach, to neglect without lost of accuracy, the otherwise important ionization-dissociation competition. Abel transformation relates the dissociation probability starting from a single ro-vibrational state, to the probability of observing a hydrogen atom at a given pixel of the detector plate. Some statistics on initial ro-vibrational distributions, together with a spatial averaging over laser focus area, lead to photofragments kinetic spectra, with well separated peaks attributed to single vibrational levels. An excellent theory-versus-experiment agreement is reached not only for the kinetic spectra, but also for the angular distributions of fragments originating from two different vibrational levels resulting into more or less alignment. Some characteristic features can be interpreted in terms of basic mechanisms such as bond softening or vibrational trapping.Comment: submitted to PRA on 21.05.200