Spatial distribution of the gain and temperature across the flow in a slit-nozzle supersonic chemical oxygen-iodine laser with transonic and supersonic schemes of iodine injection

Spatial distributions of the gain and temperature across the flow were studied for transonic and supersonic schemes of the iodine injection in a slit-nozzle supersonic chemical oxygen-iodine laser as a function of the iodine and secondary nitrogen flow rate, jet penetration parameter, and gas pumping rate. The mixing efficiency for supersonic injection of iodine (/spl sim/0.85) is much larger than for transonic injection (/spl sim/0.5), the maximum values of the gain being /spl sim/0.65%/cm for both injection schemes. Measurements of the gain distribution as a function of the iodine molar flow rate nI/sub 2/ were carried out. For transonic injection, the optimal value of nI/sub 2/ at the now centerline is smaller than that at off axis locations. The temperature is distributed homogeneously across the flow, increasing only in the narrow boundary layers near the walls. Opening a leak downstream of the cavity in order to decrease the Mach number results in a much larger mixing efficiency (/spl sim/0.8) than for a closed leak.     

Shapes of Hydraulic Fractures in the Neighborhood of Cylindrical Cavity

Journal of Mining Science - The article presents the theoretical and experimental results on propagation of hydraulic fractures in the neighborhood of an extended cylindrical cavity in an isotropic...     

Structureless modeling of power amplifiers accounting for inertial properties

The paper considers various structureless inertial non-linear models of power amplifiers and methods of their identification. Based on polynomial model with memory and Volterra model the influence of different kinds of input signals, their bandwidth and average power on precision of power amplifier modeling and complexity of model implementation.     

Correction to: Efficient Hardware Architectures for 1D- and MD-LSTM Networks

Journal of Signal Processing Systems -     

Parametric study of small-signal gain in a slit nozzle, supersonicchemical oxygen-iodine laser operating without primary buffer gas

A detailed experimental study of the gain and temperature in the cavity of a supersonic chemical oxygen-iodine laser (COIL) is carried out to find optimal values of the flow parameters corresponding to the maximum gain. It is found that high gain (>0.7%/cm) can be obtained in a COIL operating without primary buffer gas and, hence, having a high gas temperature (>250 K) in the cavity. The measurements are performed for slit nozzles with different numbers and positions of iodine injection holes. Using a diode laser-based diagnostic, the gain is studied as a function of the molar flow rates of various reagents, with optical axis position along and across the flow, and Mach number in the cavity. Maximum gain of 0.73%/cm is obtained at chlorine and secondary nitrogen flow rates of 15 mmole/s and 7 mmole/s, respectively, for a slit nozzle with transonic injection of iodine. The gain is found to be strongly inhomogeneous across the flow. For a slit nozzle with iodine injection in the diverging part of the nozzle, the values of the maximum gain are smaller than for nozzles with transonic injection. Opening a leak downstream of the cavity in order to decrease the Mach number and increase the cavity pressure results in a decrease of the gain and dissociation fraction. The gain is a nonmonotonic function of the iodine flow rate, whereas the temperature increases with increasing iodine flow. An analytical model is developed for calculating in slit nozzles the iodine dissociation fraction F and the number N of O₂ (¹Δ) molecules lost in the region of iodine dissociation per I₂ molecule