Real-time phase tracking in single-photon interferometers

A new technique for phase tracking in quantum cryptography systems is proposed that adjusts phase in an optimal way, using only as many photon counts as necessary. We derive an upper bound on the number of photons that need to be registered during phase adjustment to achieve a given phase accuracy. It turns out that most quantum cryptosystems can successfully track phase on a single-photon level, entirely with software, without any additional hardware components or extensive phase-stabilization measures. The technique is tested experimentally on a quantum cryptosystem.     

Heat exchange on the initial thermal section in stabilized turbulent air flow in circular pipes and rectangular channels

Formulas are proposed for an analysis of the local and mean heat exchange on the initial thermal section for stabilized turbulent air flow in circular pipes and rectangular channels on the basis of an extension of test results.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 2, pp. 215–223, February, 1971.     

Possible existence of periodic temperature field during electrical heating

The temperature distribution in a metal rod heated by electric current is analyzed qualitatively.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 5, pp. 825–827, May, 1982.     

Studies of silver iodide ice-forming activity. i. influence of the aerosol particle size on the ice-forming activity at —20°C

Silver iodide ice-forming activity has been studied at the supercooled fog temperature —20°C. The number of ice crystals calculated per gram reagent depends greatly on the aerosol particle mean cubed radius. The analysis of published data shows that this is the principal cause of a considerable divergence in the data on silver iodide ice-forming activity obtained by various authors.     

Application of the laplace-carson integral transform method to the theory of nonstationary flows of a viscoplastic medium

We show that with the application of a Laplace-Carson integral transform the problem concerning the development of a gradient flow of a viscoplastic medium between parallel walls reduces to the solution of a system of functional equations.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 1, pp, 94–99, July, 1970.     

Optical properties of structures with ultradense arrays of Ge QDs in an Si matrix

The structural and optical properties of ultrathin Ge insertions in an Si matrix were studied. Transmission electron microscopy revealed the spontaneous formation of arrays of disk-shaped quantum dots (QDs) with a small lateral size (3–10 nm) at a nominal Ge insertion thicknesses, from submonolayer to nearly critical, for the transition to 3D growth by the Stranski-Krastanow mechanism. Optical study revealed type-I band alignment in these structures, which results from the strong contribution of the electron-hole Coulomb interaction overpowering the repulsion potential for an electron existing in the Ge conduction band. The small lateral size of QDs lifts the selection rule prohibiting indirect recombination in the inverse k space. At the same time, the high surface density of QDs (10¹²–10¹³ cm^?2) and the possibility of their stacking with the use of ultrathin Si spacers allows the obtainment of an ultrahigh volume density of QDs (up to 10¹⁹ cm^?3), which is necessary to achieve stimulated emission in Si. A sample with stacked QDs formed by 0.7-nm-thick Ge insertions exhibited a superlinear increase of the photoluminescence (PL) intensity, accompanied by narrowing of the PL line. The doping of Ge-Si structures with donors allows for a drastic increase in the PL intensity at high temperatures, which prevents depletion of the active region in weakly localized electrons.     

Thermodynamics of Rubidium Uranoniobate

The standard enthalpies of formartion of crystalline -RbNbUO₆, -RbNbUO₆, and RbNbUO₆·H₂O at 298.15 K were determined. The temperature dependence of the heat capacity of -RbNbUO₆, RbNbUO₆·H₂O, and -RbNbUO₆ was studied in the range 60-300 K. The thermodynamic functions and equilibrium constants of the reactions involved in synthesis of rubidium uranoniobates at various temperatures were calculated.     

Simulation of the Phase of Establishment of the Rheometric Flow of a Viscoelastic Fluid

The flow between two plates in the phase of establishment for the case of a viscoelastic fluid in comparison with a Newtonian fluid is investigated numerically and analytically. The quantitative and qualitative features of the flow are analyzed. It is noted that in a number of cases this flow has wave features, and it is determined that the presence of viscoelasticity usually increases the time of establishment of the flow. It is pointed out that some of the revealed features of the flow can be used in experimental investigations of nonNewtonian fluids.     

Electrical Properties of WO3-Based Ceramics

The electrical properties of WO₃ceramics with Na₂O, MnO₂, and Al₂O₃additions were investigated. The effects of postsintering heat treatment, electrode material, and NiO and Co₃O₄additions were examined.     

Identification of Depth and Size of Subsurface Defects by a Multiple-Voltage Probe Sensor: Analytical and Neural Network Techniques

A theoretical study was conducted using a multiple-voltage probe sensor for detecting nonconducting inclusions in conducting media. Results show that the multiple-voltage probe sensor is capable of providing precise quantitative measurements of submerged nonconducting objects if the surface voltage response has a standard two-peak form. The standard response is observed for well-localized non-slender single inclusions below the sensor surface. In this case, the peak separation distance is associated with the inclusion depth whereas the peak magnitude is associated with the inclusion volume. Linear dependencies of the inclusion depth and the inclusion volume are observed for a wide variety of inclusion shapes. The predefined form of the surface voltage response makes it feasible to identify useful signal responses at very high noise levels. This is accomplished by using a 2D neural network classifier, based on the probabilistic neural network. A reasonable recognition error of less than 20 % is obtained if the signal-to-noise ratio is larger than or equal to 1/10. A metal casting example shows that the multiple-voltage probe sensor can measure inclusion concentrations in hot conducting melts (gas bubbles and sludge) with inclusion radii in the range from 100 to 1000 m. In contrast to existing particle counter technology, this sensor construction is simple to construct and does not require special aperture and vacuum treatment.