Algorithm of Robust Frequency Estimation in a Channel with White Gaussian Noise and Pulse Interferences

An algorithm for robust frequency estimation in a channel with additive white Gaussian noise and pulse interference is proposed. The algorithm involves iterative elimination of pulse interferences and subsequent calculation of the maximum likelihood estimate. It is demonstrated that the proposed filter-cleaner differs from the well-known Martin–Thomson filter in the functional dependence of adaptive coefficients on the estimates of parameters of distributions of the linear prediction error and the amplitude envelope of the signal. The results of mathematical modeling and numerical estimation of the threshold point of the method (0.49) are presented.     

Hydrocracking of Vacuum Gasoil on NiMoW/AAS-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Trimetallic Catalysts: Effect of the W : Mo Ratio

The effect of the W: (W + Mo) atomic ratio in NiMoW trimetallic catalysts on their catalytic and physicochemical properties is studied. The catalysts are prepared by impregnating a carrier containing amorphous aluminosilicate (AAS) and aluminium oxide with an aqueous solution containing Ni, Mo, W compounds, and citric acid. They are studied via XRF, TEM, NH₃ TPD, and low-temperature nitrogen adsorption and are tested in the hydrocracking of vacuum gasoil (VGO). The average length of a sulfide active component layer shrinks as the amount of Mo increases and the amount of W in the catalyst is reduced. XPS data indicate that the degree of sulfidation of tungsten in NiMoW trimetallic catalysts is lower than in NiW catalyst. Testing of the catalysts in hydrocracking of a straight-line VGO at 390–420°C, 16 MPa, a feedstock hourly space velocity (FHSV) of 0.71 h^?1, and a H₂: VGO ratio of 1200 L/L shows the activities of hydrodesulfurization, hydrodenitrogenation, hydrogenation, and hydrocracking grow along with the W: (W + Mo) ratio. When the process pressure is high and the amount of sulfur in the NiW feedstock is low, the catalysts have higher activity in the target reactions of VGO hydrocracking than NiMo catalyst.     

Optimization of the composition and the properties of the plastic bodies for obtaining silicon carbide products

Conclusions Based on the simplest concepts regarding the filler-plasticizer system, we derived an expression relating the ratio of the quantities of the filler and the plasticizer to the densities of the filler and the plasticizer under the condition of dense packing; a scheme of optimizing the composition of the plastic bodies was shown.It was shown that the C_pl/C_SiC ratio is determined by the mechanism of the evolution of the final structure of the silicon carbide products during the siliconizing firing process. The methods of controlling the apparent density of the filler and the density of the plasticizer were examined.We developed a plastic body requiring a lower forming load; the content of the primary silicon carbode in the original charge of the body could be brought up to 94%; the products obtained using this body possess a combination of high strength and electrophysical properties.Translated from Ogneupory, No. 4, pp. 3–6, April, 1993.     

Neutron detection efficiency of a thick lithium glass detector

The neutron detection efficiency of a 9.55 mm thick NE-912 lithium glass scintillator has been determined for the energy range from 25 keV to 2 MeV. It was measured relative to a thin, 0.835 mm thick NE-908 glass, which was determined by Monte Carlo calculations. The measured efficiency curve shows the marked effect of the ¹⁶O resonance at 442 keV, and a strong increase with energy for E_n > 1.2 MeV, due to (n,n′γ) reactions.     

Basic directions of research in the area of preparing carbon fibre materials based on hydrocellulose fibres

Conclusions -- A wide assortment of CFM based on viscose technical yarn has been developed in the VNIIPV and introduced into industry.-- Basic trends of studies in the area of preparing CFM based on HCF have been defined: improvement in the quality of viscose technical yarn; solution of ecological problems in its manufacture; optimization of technology with the purpose of improving characteristics and reducing costs; the development of CFM with qualitatively new characteristics; and the search for new regions of application.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 8–10, May–June, 1991.     

Structure and properties of a corundum-carbon refractory material sintered at 1600°C

The factors responsible for the failure of blow plugs for steel ladles used in extra furnace steelmaking technology are considered. Results of a structural study of refractories based on electrofused corundum, crystalline silicon, and artificial graphite are reported. To improve the properties of corundum-carbon refractories, the sintering temperature should be increased to 1600°C.__________Translated from Novye Ogneupory, No. 10, pp. 91 – 92, October, 2004.