Classification of Reconfigurable Parallel Mechanisms

Russian Engineering Research - The theoretically possible reconfigurable parallel mechanisms are classified, in terms of the layout of guides on the base. Formulas are derived for the...     

1/f noise and self-organized criticality in crisis regimes of heat and mass transfer

Thermal fluctuations under the transition from nucleate to film boiling of water on a wire heater and fluctuations of jet form during an outflow of superheated liquid from a pressure vessel were experimentally investigated. It has been found that power spectrum of the fluctuations has got a low frequency component corresponding to a 1/f law (flicker noise).The effect given is connected with the occurrence of nonequilibrium phase transitions in the systems: a crisis of heat transfer under the transition from nucleate to film boiling and a crisis of a flow in boiling-up of superheated liquid jet.     

A Computerized Monitoring and Control System for the Gas-Mixture Preparation Complex for Experiments on Muon-Catalyzed Fusion

A computerized system for monitoring and controlling the gas-mixture preparation complex of the TRITON installation is described. The installation is designed for experimental investigations of muon-catalyzed fusion in triple mixtures of hydrogen isotopes H/D/T over wide ranges of temperature and pressure. The system is used to control the entire complex of gas-mixture preparation, the target parameters, and the gas-mixture composition, as well as to carry out radiation monitoring. Good performance characteristics, the high reliability of the system, and the possibility of its rapid adaptation to new tasks have been demonstrated in physics experiments.     

The effect of probability of coalescence on the evolution of bubble sizes in a turbulent pipeline flow: A numerical study

A population balance method in which continuum and discrete phases are integrated is developed to simulate the evolution of polydisperse population of bubbles in a turbulent pipeline flow. The investigation is focused on the effect of the coalescence efficiency on this evolution. A dilute system of bubbles under microgravity conditions is considered. It is found that if the initial coalescence efficiency is low, a slight increase produces a significant effect on the bubble coalescence rate, and thus on the evolution of the population. If, however, the initial coalescence efficiency is high, its increase results in a marginal effect on the way the population evolves. The results of simulations are validated against experimental data on the population mean.     

A comparison of some approaches to classification problems,and possibilities to construct optimal solutions efficiently

We consider sequential linear (binary) classifiers for the case of many classes along with the linear classifiers based on determining the maximum discriminant function. It is shown that the capabilities of sequential binary classifiers are wider than those of linear classifiers. For the case of linearly non-separable training samples there are considered approaches based on minimizing the margin of misclassification and minimizing empirical risk. It is shown that problem of minimizing the margin of misclassification is polynomially solvable for a certain choice of the norm in the feature space. A refined model of the empirical risk minimization problem and its continuous relaxation are considered, a comparison with the mathematical model of SVM is done. The results of numerical experiments comparing different approaches are discussed.     

Limit Superheating of Stretched Liquid

Investigation of explosive vaporization with pulse heating of an extended liquid in a pressure range of from–10 tо +0.1 МPа revealed regimes when bubbles occur by the homogeneous fluctuation nucleation mechanism. These regimes are distinguished by a great phase transformation rate and a nucleation concentration at the moment of the attainment of a certain liquid temperature. This metastable liquid temperature is found to be the highest and is estimated by coordinates of the liquid–vapor spinodal. The kinetics of cavitation and boiling is investigated by disturbance of the heat flux of a miniature, fast-heated wire sensor. The extended liquid pressure near the sensor was set by the method of the positive pressure pulse inversion. Experimental results are generalized with application of explosive vaporization theory for the impact boiling regime at positive pressures.     

A method for automatic calibration of 3D vision systems by means of high-resolution data

Calibration of the digital projector is a necessary procedure for many 3D scanners. The proposed method for automatic calibration of a projector uses binary color templates and searches for the most stable points for minimization of decoding errors. The camera resolution must significantly exceed the projector’s resolution. The method can be easily adapted for operation with black-and-white templates.