Hydrodynamic model for electron-hole plasma in graphene

We propose a hydrodynamic model describing steady-state and dynamic electron and hole transport properties of graphene structures which accounts for the features of the electron and hole spectra. It is intended for electron-hole plasma in graphene characterized by high rate of intercarrier scattering compared to external scattering (on phonons and impurities), i.e., for intrinsic or optically pumped (bipolar plasma), and gated graphene (virtually monopolar plasma). We demonstrate that the effect of strong interaction of electrons and holes on their transport can be treated as a viscous friction between the electron and hole components. We apply the developed model for the calculations of the graphene dc conductivity, in particular, the effect of mutual drag of electrons and holes is described. The spectra and damping of collective excitations in graphene in the bipolar and monopolar limits are found. It is shown that at high gate voltages and, hence, at high electron and low hole densities (or vice-versa), the excitations are associated with the self-consistent electric field and the hydrodynamic pressure (plasma waves). In intrinsic and optically pumped graphene, the waves constitute quasineutral perturbations of the electron and hole densities (electron-hole sound waves) with the velocity being dependent only on the fundamental graphene constants.Comment: 11 pages, 6 figure

Improving the accuracy of a time lens

Cataloged from PDF version of article.A method for improving the accuracy of temporal imaging with an imperfect time lens is proposed. Signal distortion arising from complicated dispersion of the delay lines can be reduced considerably by appropriate choice of the phase-modulation function including the second harmonic of the basic modulation frequency and a specific phase shift of the modulation with respect to the main signal. The method is of particular interest for picosecond and femtosecond optical pulse generation. © 1997 Optical Society of Americ

СИСТЕМАТИЗАЦІЯ НАУКОВИХ ДОСЛІДЖЕНЬ З ПРОБЛЕМ ВИТРАТ НА ВИРОБНИЦТВО ПРОДУКЦІЇ

An important condition for the production of industrial enterprises is the effective use and restoration of productive resources, which are based on competent management process of reducing production costs. The article by bibliometric and bibliographic research, critical analysis and systematization of scientific papers published in scientific bulletin and proceedings problems in the areas of accounting, development, evaluation, analysis and management of production costs, their grouping by year, within the meaning of articles in the section authors and countries.Важным условием развития производственной деятельности промышленных предприятий является эффективное использование и воспроизводство производственных ресурсов, в основе которых лежит грамотное управление процессом снижения производственных затрат. В статье осуществлено библиометрическое и библиографическое исследование, критический анализ и систематизацию научных работ, напечатанных в научных вестниках и сборниках научных трудов по направлениям проблем учета, формирования, оценки, анализа и управления затратами на производство, их группировки по годам, по содержанию статей, в разрезе авторов и стран.Важливою умовою розвитку виробничої діяльності промислових підприємств є ефективне використання та відтворення виробничих ресурсів, в основі яких лежить грамотне управління процесом зниження виробничих витрат. В статті здійснено бібліометричне та бібліографічне дослідження, критичний аналіз та систематизацію наукових робіт, надрукованих в наукових вісниках та збірниках наукових праць за напрямами проблем обліку, формування, оцінки, аналізу та  управління витратами  на виробництво, їх групування за роками, за змістом статей, в розрізі авторів та країн

Radiative cooling of H3O+ and its deuterated isotopologues

In conjunction with ab initio potential energy and dipole moment surfaces for the electronic ground state, we have made a theoretical study of the radiative lifetimes for the hydronium ion H$_3$O$^{+}$ and its deuterated isotopologues. We compute the ro-vibrational energy levels and their associated wavefunctions together with Einstein coefficients for the electric dipole transitions. A detailed analysis of the stability of the ro-vibrational states have been carried out and the longest-living states of the hydronium ions have been identified. We report estimated radiative lifetimes and cooling functions for temperatures $<$ 200 K. A number of long-living meta-stable states are identified, capable of population trapping.Comment: Phys. Chem. Chem. Phys., 201

The Capacitive Magnetic Field Sensor

The results of a study of sensitive element magnetic field sensor are represented in this paper. The sensor is based on the change of the capacitance with an active dielectric (ferrofluid) due to the magnitude of magnetic field. To prepare the ferrofluid magnetic particles are used, which have a followingdispersion equal to 50 < [the empty set] <= 56, 45 < [the empty set] <= 50, 40 < [the empty set] <=45 and [the empty set] <= 40 micron of nanocrystalline alloy of brand 5BDSR. The dependence of the sensitivity of the capacitive element from the ferrofluid with different dispersion of magnetic particles is considered. The threshold of sensitivity and sensitivity of a measuring cell with ferrofluid by a magnetic field was determined. The experimental graphs of capacitance change of the magnitude of magnetic field are presented

Duo: a general program for calculating spectra of diatomic molecules

Duo is a general, user-friendly program for computing rotational, rovibrational and rovibronic spectra of diatomic molecules. Duo solves the Schr\"{o}dinger equation for the motion of the nuclei not only for the simple case of uncoupled, isolated electronic states (typical for the ground state of closed-shell diatomics) but also for the general case of an arbitrary number and type of couplings between electronic states (typical for open-shell diatomics and excited states). Possible couplings include spin-orbit, angular momenta, spin-rotational and spin-spin. Corrections due to non-adiabatic effects can be accounted for by introducing the relevant couplings using so-called Born-Oppenheimer breakdown curves. Duo requires user-specified potential energy curves and, if relevant, dipole moment, coupling and correction curves. From these it computes energy levels, line positions and line intensities. Several analytic forms plus interpolation and extrapolation options are available for representation of the curves. Duo can refine potential energy and coupling curves to best reproduce reference data such as experimental energy levels or line positions. Duo is provided as a Fortran 2003 program and has been tested under a variety of operating systems