The study presents the possible use of optoelectronic system for the measurement of values specific for hydrodynamics of two-phase gas very-high-viscosity liquid flow in vertical pipes. An experimental method was provided, and the findings were presented and analysed for selected values which characterise the two-phase flow.

To find effective and practical methods to distinguish gas-liquid two-phase flow patterns, new flow pattern maps are established using the differential pressure through a classical Venturi tube. The differential pressure signal was first decomposed adaptively into a series of intrinsic mode functions (IMFs) by the ensemble empirical mode decomposition. Hilbert marginal spectra of the IMFs showed that the flow patterns are related to the amplitude of the pressure fluctuation. The cross-correlation method was employed to sift the characteristic IMF, and then the energy ratio of the characteristic IMF to the raw signal was proposed to construct flow pattern maps with the volumetric void fraction and with the two-phase Reynolds number, respectively. The identification rates of these two maps are verified to be 91.18% and 92.65%. This approach provides a cost-effective solution to the difficult problem of identifying gas-liquid flow patterns in the industrial field.

In this survey paper, resonant and quasiresonant dc link inverters are reexamined for ac motor drive applications. Critical evaluation of representative topologies is based on simulation and waveform analysis to characterize current/voltage stress of components, control timing constraints and feasibility. A special concern over inverter common-mode voltage and voltage gradient du/dt limitation capacity is discussed for motor bearing and winding insulation safety. Experimental records of the laboratory developed parallel quasiresonant dc link inverter feeding induction motor confirm results of analysis. Comparative tables and simulation results demonstrate characteristic features of various schemes.

The population structures of Calanus finmarchicus, C.glacialis and C.hyperboreus were investigated in the recurrent polynya of the North Waters (NOW) in Baffin Bay during April –July 1998. Species were determined from samples collected by plankton nets of 300 ľm and 200 ľm mesh size. The highest concentration of all three species was found at the centre of study the area. C.hyperboreus was the most abundant species (44.54 ind.m –3).C.glacialis was recorded up to 27.14 ind.m –3, C.finmarchicus up to 5.63 ind.m –3 .C.finmarchicus was reproducing in the northern end of Baffin Bay.The life cycle for C.glacialis was estimated at 2 years,and that of C.hyperboreus to last at least 4 years.