Effect of electrode material on impedance spectra of metal-polyethylene structures with carbon nanotubes

The effect of an electrode material on electrical properties of a composite material based on super-high-molecular polyethylene (SHMPE) filled with carbon nanotubes has been studied using impedance spectroscopy. Using the method of replacing the sample by an equivalent electric circuit, it has been found that, depending on the electrode material, a blocking barrier with high active resistance and a space charge region adjacent to it arise in the interface region. It has been shown that the barrier height is controlled by surface electronic states of SHMPE and weakly depends on the electron work function of metal electrodes (Bardeen barrier). The characteristic times of electrical relaxation characterizing bulk and interface regions of the composite under study have been determined.     

Adaptive active noise and vibration control systems

A review of research concerned with adaptive noise and vibration control systems and performed under the supervision of Corresponding Member of the Russian Academy of Sciences V.A. Zverev at Nizhni Novgorod State University in the 1980s and 1990s is presented. The history of the subject is briefly outlined, and the theoretical foundations of the design of adaptive active control systems for random wave fields are considered. The main experimental studies performed in this area of research at the Department of Bionics and Statistical Radiophysics of Nizhni Novgorod State University are described. Promising lines of research in this area are indicated, and examples of the practical application of adaptive control systems are given.     

Influence of disorder on superconductivity in non-magnetic rare-earth nickel borocarbides

The effect of substitutional disorder on the superconducting properties of YNi₂B₂C was studied by partially replacing yttrium and nickel by Lu and Pt, respectively. For the two series of (Y, Lu)Ni₂B₂C and Y(Ni, Pt)₂B₂C compounds, the upper critical field H _c2(T) and the specific heat c _p(T, H) in the superconducting mixed state have been investigated. Disorder is found to reduce several relevant quantities such as T _c, the upper critical field H _c2(0) at T=0 and a characteristic positive curvature of H _c2(T) observed for these compounds near T _c. The H _c2(T) data point to the clean limit for (Y, Lu) substitutions and to a transition to the quasi-dirty limit for (Ni, Pt) substitutions. The electronic specific heat contribution γ(H) exhibits significant deviations from the usual linear γ(H) law. These deviations reduce with growing substitutional disorder but remain even in the quasidirty limit which is reached in the Y(Ni_1−x , Pt _x )₂B₂C samples for x=0.1.     

Generalized hydrodynamic equations in the hard-spheres model

Generalized linearized hydrodynamic equations in the hard-sphere model are considered on the basis of N.N. Bogolubov’s approximate approach to the analysis of collective interactions. The generalized matrix of transfer coefficients is shown not to be self-adjoint when the finiteness of the two-particle interaction region is taken into account.     

Upgrading of the RS-20E High-Current Accelerator for the Investigation of Shock-Wave Processes under Isochoric Energy Absorption

The scheme and parameters of the upgraded RS-20E electron beam generator on the basis of a plasma opening switch (POS) are presented. The output unit of the POS is modified to allow the use of optical diagnostics in investigating wave processes generated in transparent targets by the electron beam of the accelerator. A new optical diagnostic system is also presented. Its scheme allows the four-frame electron-optical registration of a sample in both its own glow and in the laser shadow during propagation of the shock wave generated by the electron beam.     

Experimental investigation of high-energy photon splitting in atomic fields

Data analysis of an experiment in which photon splitting in atomic fields was observed is presented. The experiment was performed at the tagged photon beam of the ROKK-1M facility at the VEPP-4M collider. In the energy region of 120-450 MeV, statistics of 1.6x10(9) photons incident on the BGO target was collected. About 400 candidate photon-splitting events were reconstructed. Within the attained experimental accuracy, the experimental results are consistent with the calculated exact atomic-field cross section. The predictions obtained in the Born approximation differ significantly from the experimental results.     

Qutrit state engineering with biphotons

The novel experimental realization of three-level optical quantum systems is presented. We use the polarization state of biphotons to generate a specific sequence of states that are used in the extended version of four-state QKD protocol quantum key distribution protocol. We experimentally verify the orthogonality of the basic states and demonstrate the ability to easily switch between them. The tomography procedure is employed to reconstruct the density matrices of generated states.