Bit error rate in eigenchannels of SVD-based MIMO system

In this paper, we derive the exact closed-form expressions on the bit error rate (BER) in the individual eigenchannels of the singular value decomposition (SVD)-based multiple-input multiple-output (MIMO) system with the perfect channel state information (CSI) at both the transmitter and receiver. It is assumed that a MIMO system operates in uncorrelated Rayleigh fading environment and uses M-ary quadrature amplitude modulation (BPSK, QPSK, 16-QAM and 64-QAM). The obtained results are applicable for the systems with two eigenchannels, i.e. with M transmit and 2 receive antennas or with 2 transmit and N receive antennas. Besides the exact expressions, the corresponding high signal-to-noise ratio (SNR) approximations are also presented.     

Sequential mechanism of electron transport in the resonant tunneling diode with thick barriers

A frequency-dependent impedance analysis (0.1–50 GHz) of an InGaAs/InAlAs-based resonant tunneling diode with a 5-nm-wide well and 5-nm-thick barriers showed that the transport mechanism in such a diode is mostly sequential, rather than coherent, which is consistent with estimates. The possibility of determining the coherent and sequential mechanism fractions in the electron transport through the resonant tunneling diode by its frequency dependence on the impedance is discussed.     

The formation of urchinlike nanostructures under thermal oxidation and depassivation of iron particles

Methods of scanning electron microscopy with an X-ray probe, Raman spectroscopy, and thermogravimetry are used to study the morphology and composition of metal–oxide nanostructures obtained by thermal oxidation of spherical microparticles of iron powder with a diameter of 1–3 μm. It is shown that unidimensional hematite nanoflakes and fibers grow under atmospheric annealing at 300°C and above in the radial direction from powder microparticles, which is accompanied by depassivation and acceleration of corrosion layer growth. An increase in temperature and oxidation time results in transformation of microparticles into urchinlike multilayer nanoparticles consisting of elongated crystalline α-Fe₂O₃ nanowhiskers growing normally to the surface of the particle consisting of an iron core and shells of the magnetite and hematite phases. Growth of hematite nanowhiskers continues until the metallic core is completely oxidized.     

Uniform and “Nodule” Corrosion of Zirconium Alloys under Service Conditions

Results concerning uniform and nodule (local) corrosion obtained in SF NIKIÉT are reviewed. The applicability of the electrotechnical theory of high-temperature oxidation of metals to zirconium alloys is analyzed. The conditions of occurrence of nodule corrosion are determined, and the results of a study of process channels and fuel assemblies of RBMK reactors after service at nuclear power plants (NPP) are generalized.     

An acousto-optic modulator of optical radiation at the double acoustic frequency

An acousto-optic (AO) modulator that converts a frequency shift of optical radiation into the amplitude modulation of light at the double acoustic frequency is proposed and described. A ТеО₂ singlecrystal modulator mockup that was developed and tested provides the amplitude modulation of linearly polarized optical radiation at a wavelength of 0.63 μm at the double acoustic frequency, which is equal to ~82MHz.     

Determination of the turbulent diffusion and heat-conduction coefficients in mine workings

Makeev Scientific Research Institute. Translated from Fiziko-tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 5, pp. 90–92, September–October, 1990.     

Analysis of nonlinear heat conduction based on determining the front of temperature perturbation

An analytical solution of nonlinear problem of heat conduction is derived using an integral method of heat balance. In order to improve the accuracy of solution, the temperature function is approximated by polynomials of higher degrees. The polynomial coefficients are determined using additional boundary conditions which are found from the basic differential equation and preassigned boundary conditions including the conditions on the front of temperature perturbation. It is demonstrated that the introduction of additional boundary conditions even in a second approximation results in a significant increase in the accuracy of solution of the problem.     

Sturm-liouville problem for a differential equation of second order with discontinuous coefficients

Using, as an example, a special Sturm-Liouville boundary-value problem for a differential equation of second order with discontinuous coefficients, the authors describe a method of constructing a closed orthonormalized system of functions that is common to the entire domain of determination. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 748–753, July–August, 2000.     

Computer Prediction of Catalytic Reforming of Naphtha Cuts

Experience in the use of a computer system (CS) developed with consideration of the physicochemical properties of catalytic reforming of naphtha cuts for testing and selection of the type of Pt catalyst, optimization of the conditions of its treatment and industrial use, prediction of the duration of the operating cycle between regenerations, and the increase in the efficiency of operation of industrial units in consideration of the process technology and hydrocarbon composition of the refined feedstock is described.