Reducing Dangerous Effects of Unsymmetrical Dimethylhydrazine as a Liquid Propellant by Addition of Hydroxyethylhydrazine—Part I: Physical Properties

In this work, the effect of low volatile hydroxyethylhydrazine (HEH) as a solute on unsymmetrical dimethylhydrazine (UDMH) has been studied in order to reduce harmful effects of UDMH vapors. Desirable physical properties of binary mixtures UDMH/HEH have been measured and compared to pure UDMH. These properties include boiling point, viscosity, density, and vapor pressure that are important for using binary mixtures of UDMH/HEH as less dangerous liquid propellants. Due to the formation of strong hydrogen bonding between UDMH and HEH, the volatility of UDMH has been reduced appreciably upon the addition of HEH. It is indicated that the measured physical properties may deviate significantly compared to corresponding predicted values. Binary mixtures of UDMH/HEH can also react spontaneously in contact with nitrogen tetroxide (NTO) and red fuming nitric acid (RFNA), so they can be called hypergolic propellants.     

Thermodynamics of extraction of Re O 4 − from aqueous sulfuric acid media with Tri-n-butyl phosphate dissolved in kerosene

Rhenium distribution between Tri-n-butyl phosphate (TBP) dissolved in kerosene and sulfuric aqueous media is investigated under different temperatures, acidities, and TBP concentrations. Results show an exothermic extraction reaction with a distribution factor that decreases with the increase of the temperature and increases with the increase of the acidity and the TBP concentration. The stoichiometry of the reaction indicates neutralization of 1 mole of H⁺ with 1 mole of ReO ₄ ⁻ and solvating of a neutral molecule with four molecules of TBP. The structure of the complexes formed is, therefore, 4TBP · HReO₄. The apparent Gibbs free energy of the formation of 4TBP · HReO₄ from TBP, ReO ₄ ⁻ , and H⁺ is determined to be equal to −66,989 + 219.8 T J/mole.     

Predicting the Detonation Velocity of CHNO Explosives by a Simple Method

A simplified method is shown, based on a semi‐empirical procedure, to estimate the detonation velocities of CHNO explosives at various loading densities. It is assumed that the product composition consists almost of CO, CO₂, H₂O and N₂ for oxygen‐rich explosives. In addition solid carbon and H₂ are also counted for an oxygen‐lean explosive. The approximate detonation temperature, as a second needed parameter, can be calculated from the total heat capacity of the detonation products and the heat of formation of the explosive by PM3 procedure. The detonation velocities of some well‐known CHNO explosives, calculated by the simple procedure, fit well with measured detonation velocities and the results from the well‐established BKW‐EOS computer code.     

Modeling metallurgical responses of coal Tri-Flo separators by a novel BNN:a "Conscious-Lab" development

Tri-flo cyclone,as a dense-medium separation device,is one of the most typical environmentally friendly industrial techniques in the coal washery plants.Surpris...     

Feature Extraction in Fractional Fourier Domain for Classification of Passive Sonar Signals

Journal of Signal Processing Systems - The acoustic signals radiated from the marine vessels contain information about their machinery characteristics that can be useful for the detection and...     

Phase II monitoring of survival times with categorical covariates

Monitoring surgical outcomes is of paramount importance especially by accounting for health conditions of the patients prior to surgery. However, the problem arises as the effect of some covariates is pronounced but cannot be measured. In this paper, in order to deal with the effect of measured and unmeasured (categorical) covariates simultaneously, a class of survival analysis regression models called accelerated failure time (AFT) model and discrete frailty models is integrated and some Phase II risk-adjusted control schemes are devised to monitor the patients' lifetime. Three monitoring procedures including the cumulative sum (CUSUM), exponentially weighted moving average (EWMA), and probability limits-based control charts are developed in the presence and absence of censored observations. The performance analysis reveals that the proposed AFT frailty-based CUSUM control chart outweighs the competing counterparts in detecting shifts under various scenarios. Subsequently, two CUSUM control charts have been constructed corresponding to the cases of neglecting both the unmeasured and measured covariates and ignoring just the unmeasured covariate. The results clearly indicate that the detection ability for both of the mentioned CUSUM control charts declines, and including the unmeasured and measured covariates is critical while monitoring surgical outcomes. Finally, a real case study in a cardiac surgical center in the United Kingdom has been provided to investigate the application of the proposed AFT frailty-based CUSUM control scheme.     

A new method for layer 2 loop prevention in software defined networks

Telecommunication Systems - Broadcast storm refers to the bandwidth saturation caused by broadcast traffic flows when a loop exists and it can quickly lead to the network failure. In legacy...     

Use of INT to determine the respiratory activity of immobilised and free Penicillium chrysogenum

The specific oxygen uptake rates (OUR) of k-carrageenan-immobilised and free cell cultures of Penicillium chrysogenum were determined using an oxygen electrode in a closed chamber. This was compared with the respiratory activity determined by the extent of staining with iodonitrophenyl tetrazolium chloride (INT). The degree of INT staining correlated with the OUR; an increase in INT deposition corresponding to an increase in the measured OUR. The INT staining technique could therefore be used to determine cell respiratory activity. In this way a profile of fungal cell activity throughout immobilised cell aggregates and free cell pellets was determined. In both types of cell culture, after the initial growth period only the peripheral biomass was observed to be active.     

Modeling the effects of ore properties on water recovery in the thickening process

A better understanding of solid-liquid separation would assist in improving the thickening performance and perhaps water recovery as well. The present work aimed to develop an empirical model to study the effects of ore properties on the thickening process based on pilot tests using a column. A hydro-cyclone was used to prepare the required samples for the experiments. The model significantly predicted the experimental underflow solid content using a regression equation at a given solid flux and bed level for different samples, indicating that ore properties are the effective parameters in the thickening process. This work confirned that the water recovery would be increased about 5% by separating the feed into two parts, overflow and underflow, and introducing two different thickeners into them separately. This is duo to the fact that thickeners are limited by permeability and compressibility in operating conditions.     

Effect of particle size on the optical properties of lead zirconate titanate nanopowders

Nanopowder samples of lead zirconate titanate (Pb_1.1Zr_0.52Ti_0.48O₃ or PZT) were prepared by the sol‐gel method with controlled pH values. The samples were characterized using FTIR spectroscopy, XRD, FE‐SEM, and TEM techniques. Most of the peaks in the XRD pattern were related to the coexistence of tetragonal‐rhombohedral phases and confirmed the formation of PZT with a perovskite structure. Also, the crystallite size of PZT nanopowders was in a range of 17‐28 nm. FTIR spectroscopy revealed a longitudinal optical (LO) and transverse optical (TO) phonon modes corresponding to the stretching vibration of Ti‐O and Zr‐O bonds. The influence of pH values on the LO and TO phonon modes, LO‐TO splitting, refractive index n(ω), extinction coefficient k(ω), and the real ?₁(ω) and imaginary ?₂(ω) parts of dielectric function was discussed. These properties were investigated in the mid‐infrared region (450‐750 cm^?1). The energy loss function Im[?1/(?)] of PZT nanopowders was obtained by Kramers‐Kronig dispersion relations. The TO phonon frequency decreases with increasing crystallite size of the PZT samples. This effect does not happen at pH 8 to pH 9. As the crystallite size increased from 17.26 nm (at pH 5) to 27.25 nm (at pH 7), the LO‐TO splitting increased as well. This result showed that the optimum pH for absorption of IR radiation and optical application was at pH 7.