Interaction of Components in Glass-Forming Melts of Iron and Nickel with Titanium,Zirconium, and Hafnium II. Temperature–Concentration Dependence of Thermodynamic Mixing Functions of Liquid Alloys

Powder Metallurgy and Metal Ceramics - The thermodynamic properties of liquid alloys in glass-forming systems were described in the framework of the associated solution model (ASM) according to the...     

An Identification Algorithm for Dynamic Systems with a Functional in the Frequency Domain

A parametric identification algorithm for dynamic systems is designed by the method maximum likelihood estimation in a time domain. Since the minimizing functional is formed in the frequency domain, the algorithm acquires new useful properties, mostly due to the suppression of disturbances through the choice of the working frequency ranges. The algorithm is modified such that time-shift disturbances of the recorded signal are suppressed.     

Hydraulic resistance of plane channels and annulus with different roughness on opposite walls

A new method for prediction of hydraulic resistance for a turbulent flow in plane channels and annulus is proposed. In spite of the importance of this issue, only very few publications devoted to the investigation into hydrodynamics in these channels are available, and there are no methods for predicting hydraulic resistance of a flow in these channels at all. The flow in channels with different roughness on the walls is described using the Prandtl semiempirical theory of a turbulent boundary layer. The flow in a channel cross-section is divided into two noninteracting layers of different thickness flowing along the walls with different roughness. The basic balance correlations are derived for a plane channel. To match the velocity profiles of both layers at the interface point, a logarithmic velocity profile is used. This yields a closed system of equations for predicting hydraulic resistance in plane channels with a given different roughness on opposite walls. It is demonstrated that the obtained correlation may be used for predicting hydraulic resistance in annulus as well. Experiments were carried out with a water flow in an annulus. Each annuli consisted of a pipe having a smooth wall into which a rod with artificial roughness on the surface was inserted coaxially. Two types of roughness were investigated: trapezoid and threadlike ones. Comparison of the predictions with the experimental data confirmed the validity of the proposed method. It can be used in designing flowpaths of various power installations.     

A method of determining the dynamic error of optical trajectory measurement stations

The need to take into account the dynamic error of optical trajectory measurement stations in order to increase the precision with which the flight trajectory of aircraft is determined, is evaluated. An algorithm for determining the dynamic error is presented and a calculation of the dynamic error for an optoelectronic station is given.     

Improving the match between the daily solar insolation peak and electrical peak demand

Within the next decade photovoltaic solar systems will be used more extensively for generating electricity. The value of that electricity, and the system is directly related to the degree to which its availability coincides with the customers' peak demand. For most utilities and other grid-connected users the peak demand is in the afternoon while peak solar insolation occurs at noon. This paper describes a method of attaining coincidence of the energy collected with the demand for energy. The approach used is to vary the azimuth angle of the collector panel, then determine the corresponding time shift in the peak collection point along with the total energy collected. Results show a 60° shift in azimuth has a corresponding time shift of 1 hr and 40 min in the summer with a small gain in total energy collected. However, the winter time shift is only 1 hr, 20 min and the loss of total energy is 28 per cent. A significant improvement is made to match the demand peak by varying the azimuth angle of the solar collector with a total energy loss that may be acceptable for many users. The results presented here can be used to maximize the value of the photovoltaic systems to specific utilities and other grid-connected users.     

Direct Method for Forming the Optimal Open Loop Control of Aerial Vehicles

Journal of Computer and Systems Sciences International - A direct method for finding the optimal open loop control of an aircraft is proposed. It is based on the preliminary parameterization of...     

Identification of Aerodynamic Coefficients of Longitudinal Movement and Error Estimates for Onboard Measurements of Supercritical Angles of Attack

We propose an identification method for the aerodynamic coefficients of the lift force, drag force, and pitch moment in the supercritical range of angles of attack. The investigated models take into account the hysteresis with respect to the angle of attack, which is the main specific feature of aerodynamic coefficients in the specified range. Also, we consider the problem to find and correct errors of onboard measurements in the channels of the angle of attack and the air speed and the computational model for the forces and moments created by engines with a deflected thrust vector. We provide processing examples for the flight test data obtained during maneuvers on supercritical angles of attack; they confirm the efficiency of the proposed methods.     

Structure and properties of nanostructured ZnO arrays and ZnO/Ag nanocomposites fabricated by pulsed electrodeposition

We investigate the structure, surface morphology, and optical properties of nanostructured ZnO arrays fabricated by pulsed electrodeposition, Ag nanoparticles precipitated from colloidal solutions, and a ZnO/Ag nanocomposite based on them. The electronic and electrical parameters of the ZnO arrays and ZnO/Ag nanocomposites are analyzed by studying the I–V and C–V characteristics. Optimal modes for fabricating the ZnO/Ag heterostructures with the high stability and sensitivity to ultraviolet radiation as promising materials for use in photodetectors, gas sensors, and photocatalysts are determined.