Reducibility of Linear Time-Varying Systems of Special Form with Control and Measurements

Journal of Computer and Systems Sciences International - This paper considers some classes of linear time-varying systems with control and output vectors that can be reduced to time-invarint...     

Role of Vanadium in Aluminum Electrolyzer Melts

Metallurgist - The article provides results of testing excess introduction of vanadium into a molten aluminum cell through baked anodes. This stage of special technology is preliminary and required...     

Production of Nickel–Chromium Coatings from Powder by Laser Cladding

Russian Engineering Research - The use of self-fluxing Ni12CrFe and NiCr16SiB3 powder in laser cladding within a protective atmosphere (argon) is considered. The characteristics of the powder are...     

Emergency Control of a Quadrocopter in Case of Failure of Two Symmetric Propellers

In this work, we simulate the motion of a quadcopter when two symmetric propellers fail and the full thrust is gradually decreasing on each of the remaining propellers. Applying a control obtained in standard mode leads to the flying vehicle falling down. We pose and solve the problem of synthesizing a bounded control law that lets one land the flying vehicle. We consider numerical modeling problems that arise in the implementation of the proposed mathematical model of a quadcopter.     

Ladle service under the conditions of vacuum-oxygen decarburization

The Izhstal plant has created a technology for treating corrosion-resistant steel by the method of VOD in a 30-ton ladle. The lining of the ladle is made of periclase-chromite refractories produced by the Magnezit Works JSC. The effect of the process parameters and lining patterns on the endurance of the ladle was studied in development of the process. The main factors determining the wear of the functional layer of the lining are the density of its joints, the composition of the slag of the refining period, the intensity of the mixing, and the thermal regime of the ladle between the heats. The pattern of the lining has been improved by reinforcing the slag line. The mixing regimes and the composition of the killing mixture have been improved where the consumption of lime and the proportion of aluminum to silicon are concerned. These measures have increased the endurance of the ladles by a factor of 2.2 and that of the refractory roofs by a factor of 2.5. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 41–43, May, 2000.     

Gas phase hydrodechlorination of chlorinated aromatic compounds on nickel catalysts

Supported Ni/-Al₂O₃ catalysts were studied in the gas phase hydrodechlorination of substituted chlorobenzenes. The catalytic properties of the catalysts were shown to be determined by the metal nickel. A correlation between the rate of the gas phase hydrodechlorination of substituted chlorobenzene and donor-acceptor properties of substituents was established. The electron-donor substituents increase and the electron-acceptor ones decrease their reactivity. The correlation analysis of data treated via the Hammett equation shows that hydrodechlorination on Ni/-Al₂O₃ catalysts is a reaction of electrophilic type.     

Configuration of a cloud of detonation products during expansion in air

Shadowgraph techniques are used to record the configuration of detonation products in air from various kinds of high-explosive charges with spherical and cxlindrical geometries. It is established that the cloud of detonation products from a cylindrical charge after expansion to its maximum size departs considerably from a spherical configuration. The cloud of detonation products attains its ultimate size at a distance of 25–30 times the initial radius, contrary to numerical results, which indicate that this distance does not exceed 15 or 16 times the initial radius of the charge.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 4, pp. 121–126, July–August, 1991.     

Piezoelectric K0.5Na0.5NbO3 Ceramics Textured Using Needlelike K0.5Na0.5NbO3 Templates

Improved performance by texturing has become attractive in the field of lead‐free ferroelectrics, but the effect depends heavily on the degree of texture, type of preferred orientation, and whether the material is a rotator or extender ferroelectric. Here, we report on successful texturing of K_0.5Na_0.5NbO₃ (KNN) ceramics by alignment of needlelike KNN templates in a matrix of KNN powder using tape casting. Homotemplated grain growth of the needles was confirmed during sintering, resulting in a high degree of texture parallel to the tape casting direction (TCD) and the aligned needles. The texture significantly improved the piezoelectric response parallel to the tape cast direction, corresponding to the direction of the strongest <001>_pc orientation, while the response normal to the tape cast plane was lower than for a nontextured KNN. In situ X‐ray diffraction during electric field application revealed that non‐180° domain reorientation was enhanced by an order of magnitude in the TCD, compared to the direction normal to the tape cast plane and in the nontextured ceramic. The effect of texture in KNN is discussed with respect to possible rotator ferroelectric properties of KNN.