Iteration scheme for accelerometer unit calibration by a guaranteeing approach

Methods for accelerometer unit calibration are usually based on sufficiently strict requirements on the knowledge of the gravity orientation with respect to the unit (of the order of fractions of an arc minute). But it is not always possible to know the orientation with such high accuracy. In the present paper, we consider an approach to accelerometer unit calibration for whose implementation it suffices to have rough angular information (of the order of tens of arc minutes). We use a guaranteeing approach to calculate optimal schemes calibration experiments and propose an iterative scheme of calibration.     

Physicochemical features of the formation of siliceous porous mesophases

Data on the optimization of alkalinity of the reaction mixture and the reaction temperature in the formation of the siliceous porous mesophase material C₁₆−SiO₂-MMM are presented. A criterion for the evaluation of the level of structure optimization for mesoporous mesophases is formulated. Measurements of the texture parameters of the materials treated in acidic media led to the assumption that the walls in the pure siliceous C₁₆−SiO₂-MMM system consist of separate blocks, which, apparently, are not bound completely to one another by chemical interactions. For Part 2, see Ref. 1. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1685–1691, October, 2000.     

Physicochemical Properties of Mesoporous Mesophase Silicate Materials Formed via the Electrostatic S+I– Mechanism

The formation of the structure of a highly organized silicate mesoporous mesophase material (MMM) with hexagonal packing via the S⁺I^–reaction pathway and MMM-based aluminosilicates (Al,Si)-MMM and titanosilicates (Ti,Si)-MMM with different concentrations of the elements are considered. The structural, textural, and catalytic properties of the materials are studied.     

Mechanism of the formation of porous silicate mesophases

The formation of mesoporous mesophase systems prepared by precipitation of soluble forms of SiO₂ at the surface of micelles of cetyltrimethylammonium cations was examined. A molecular mechanism of the formation of a silicate coating and a macroscopic mechanism of the formation of a mesophase were found and discussed. A combination of these mechanisms describes the processes proceeding during the synthesis. It can also explain the observed changes in the structure and texture characteristics of the mesophase.     

Physicochemical features of the formation of siliceous porous mesophases

The formation of mesoporous mesophase materialsvia precipitation of soluble SiO₂ forms on the surface of cationic cetyltrimethylammonium micelles was studied. The main physicochemical factors determining the formation of siliceous mesoporous materials and providing an explanation of the observed changes in the structural and textural characteristics of the materials were identified and discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1845–1851, October, 1999.     

Physicochemical features of the formation of siliceous porous mesophases

The formation of siliceous mesoporous mesophase materials (SiO₂-MMM) prepared by precipitation of soluble forms of SiO₂ with alkyltrimethylalkylammonium bromide C _n TMABr (n=12, 14, 16, 18 is the number of carbon atoms in the alkyl chain) was investigated. An increase in then value has no influence on the mechanism of formation of SiO₂-MMM but causes an increase in the size and volume of mesopores with the mesopore specific surface area and wall thickness remaining virtually constant.     

A “telescopic” system in the calibration problem for strapdown inertial navigation systems

An algorithm for the bench calibration of strapdown inertial navigation systems is studied. This algorithm was developed at the Moscow Institute of Electromechanics and Automatics. A mathematical model for the calibration process is constructed. A method for representing the original calibration problem in the form of a standard estimation problem is proposed with the aid of a so-called “telescopic” system. On the basis of the original algorithm, a new calibration algorithm is constructed; this new algorithm allows one to improve the estimation accuracy for the parameters of accelerometer and gyroscope units. The maximum attainable estimation accuracy for these parameters is determined.     

Physicochemical features of the formation of siliceous porous mesophases. 4. Effect of duration and temperature of the hydrothermal treatment on the structural and textural properties

The results of investigation of mesoporous mesophase materials C12--SiO₂--MMM and C16--SiO₂--MMM prepared at the optimized composition of the reaction mixture and different durations of hydrothermal treatment (HTT) at 120 °C and 140 °C are presented. Hydrothermal treatment at 120 °C influences slightly the specific surface area and the volume of the mesopores but gives a more ordered structure. Prolonged HTT at 140 °C results in irreversible structure degradation. The samples obtained with the optimal HTT duration are characterized by the minimum width of X-ray reflections, the maximum surface and volume of mesopores, and the minimum external surface.