Dynamics of volumetrically heated matter passing through the liquid-vapor metastable states

Remaining within the pure hydrodynamic approach, we formulate a self-consistent model for simulating the dynamic behavior of matter passing through metastable states in the two-phase liquid-vapor region of the phase diagram. The model is based on the local criterion of explosive boiling, derived by applying the theory of homogeneous bubble nucleation in superheated liquids. Practical application of the proposed model is illustrated with hydrodynamic simulations of a volumetrically uniformly heated planar layer of fused silica SiO2. Implications for experimentally measurable quantities are briefly discussed. A newly developed equation of state, based on the well known QEOS model and capable of handling homogeneous mixtures of elements, was used in the numerical simulations.Comment: 14 pages, 9 figure

Flame colour analysis for the droplet combustion of water-in-diesel emulsions

The flame properties surrounding a small size fuel droplet are difficult to investigate due to the infinitesimal size, weak chemiluminescence and relatively fast combustion process. The present work focuses mainly on the flame colour detection and analysis of the combustion of an isolated fuel droplet. The tested fuels are diesel and its water emulsions at different mixing concentrations. High speed colour imaging and digital image processing have been applied for tracking droplet ignition, secondary atomization, and flame chemiluminescence. Side ignition of the droplet reduced interferences in visualizing flame spread during ignition and propagation. Flame propagation starts from the heating side all around the droplet, before the development of the more dominant yellow sooty flame. Flame chemiluminescence during the overall droplet lifetime has been evaluated using the digital flame colour discrimination (DFSC) approach of analysis. This analysis has been used for demonstrating the effect of emulsifying diesel by water in enhancing its combustion characteristics. Droplet secondary atomization and sub-droplet generation has also been tracked and analysed. The chemiluminescence of the flame surrounding each individual sub-droplet has been analysed using the same DFSC scheme. From the analysis, it is shown that the sub-droplets burn in a premixed like mode, especially at a later stage, rather than the diffusive mode of the original droplet.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Uncertainty behind the veil of ignorance

This paper argues that the decision problem in the original position should be characterized as a decision problem under uncertainty even when it is assumed that the denizens of the original position know that they have an equal chance of ending up in any given individual's place. It argues for this claim by arguing that (a) the continuity axiom of decision theory does not hold between all of the outcomes the denizens of the original position face and that (b) neither us nor the denizens of the original position can know the exact point where discontinuity sets in, because the language we employ in comparing different outcomes is ineradicably vague. It is also argued that the account underlying (b) can help proponents of superiority in value theory defend their view against arguments offered by Norcross and Griffin

Study of Heat Pipe Thermal Performance with Internal Modified Geometry

The aim of this study was to investigate the effect of inserting a new internal tube packing (TP) on the thermal performance of a thermosyphon heat pipe (THP). The THP pipe was made from copper with an inner diameter of 17.4 mm and length of 600 mm. The new internal tube packing (TP) had a central copper disc with two copper tubes soldered onto both sides to transport vapor and condensate. The upper tube or riser had an inner diameter of 8.3 mm and was 300 mm long; it was connected to a hole in the disc from the upper side to transport the steam to the condenser section. The lower tube or downcomer had an inner diameter of 5 mm, was 225 mm long and was connected to the lower side of the disc to collect the condensate and transport it to the evaporator. The TP was inserted inside the THP to complete the design of the improved heat pipe (TPTHP). Experimental results showed that the TPTHP reduces the transit time from 16 to 11 min and the thermal resistance by 17–62% based on the input power and depending on the conditions of the THP. The results also showed that the inclination angle and filling ratio have no effect on the thermal resistance of the TPTHP

Creation of a homogeneous plasma column by means of hohlraum radiation for ion-stopping measurements

In this work, we present the results of two-dimensional radiation-hydrodynamics simulations of a hohlraum target whose outgoing radiation is used to produce a homogeneously ionized carbon plasma for ion-beam stopping measurements. The cylindrical hohlraum with gold walls is heated by a frequency-doubled ($\lambda_l = 526.5$ $\mu m$) $1.4$ $ns$ long laser pulse with the total energy of $E_l = 180$ $J$. At the laser spot, the peak matter and radiation temperatures of, respectively, $T \approx 380$ $eV$ and $T_r \approx 120$ $eV$ are observed. X-rays from the hohlraum heat the attached carbon foam with a mean density of $\rho_C = 2$ $mg/cm^3$ to a temperature of $T \approx 25$ $eV$. The simulation shows that the carbon ionization degree ($Z \approx 3.75$) and its column density stay relatively stable (within variations of about $\pm7\%$) long enough to conduct the ion-stopping measurements. Also, it is found that a special attention should be paid to the shock wave, emerging from the X-ray heated copper support plate, which at later times may significantly distort the carbon column density traversed by the fast ions.Comment: 12 pages, 12 figure

Synthesis And Characterization Of Two New Antimony Phosphates Co0,5alsb(PO4)3 And Mg0,5fesb(PO4)3

Two new antimony phosphates Co0,5AlSb(PO4)3 and Mg0,5FeSb(PO4)3 were synthesized for the first time by the solid-state reaction method. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Co0,5AlSb(PO4)3 crystallizes in the space group R-3c (N°167) (ah = 8.23±0.01Ǻ, ch = 21.94±0.02Ǻ). Mg0,5FeSb(PO4)3 crystallizes in the monoclinic space group P21/n (N°14) (am =11.54 Ǻ, bm = 8.83± 0.02 Ǻ, cm = 8.39± 0.01 Ǻ, β = 96.67°± 0.09). Raman and infrared spectra were recorded and assignments of the stretching and bending vibrations of the PO43- tetrahedra were made. The number of the peaks observed is in good agreement with that predicted by the factor group analysis of the R-3c et P21/n space group respectively. Vibrational spectral studies of two antimony phosphates were collected in-situ at room-pressure and at elevated temperatures, up to 430 oC. At elevated temperatures in air, Mg0,5FeSb(PO4)3 seems to be stable, but Co0,5AlSb(PO4)3 show a transition at 380°C and decomposes at 930°C. This result has been confirmed by differential scanning calorimetric study (DSC).Two new antimony phosphates Co0,5AlSb(PO4)3 and Mg0,5FeSb(PO4)3 were synthesized for the first time by the solid-state reaction method. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Co0,5AlSb(PO4)3 crystallizes in the space group R-3c (N°167) (ah = 8.23±0.01Ǻ, ch = 21.94±0.02Ǻ). Mg0,5FeSb(PO4)3 crystallizes in the monoclinic space group P21/n (N°14) (am =11.54 Ǻ, bm = 8.83± 0.02 Ǻ, cm = 8.39± 0.01 Ǻ, β = 96.67°± 0.09). Raman and infrared spectra were recorded and assignments of the stretching and bending vibrations of the PO43- tetrahedra were made. The number of the peaks observed is in good agreement with that predicted by the factor group analysis of the R-3c et P21/n space group respectively. Vibrational spectral studies of two antimony phosphates were collected in-situ at room-pressure and at elevated temperatures, up to 430 oC. At elevated temperatures in air, Mg0,5FeSb(PO4)3 seems to be stable, but Co0,5AlSb(PO4)3 show a transition at 380°C and decomposes at 930°C. This result has been confirmed by differential scanning calorimetric study (DSC)

Molecular Diagnosis of Brucella species in Baghdad

Brucellosis is possess a significant public health problem in Baghdad. In this study, we investigated the potential role of the PCR assay in detection of Brucella species, from patients suspect to have brucellosis, using blood samples in both human and animal. To establish a PCR technique for diagnosis of active brucellosis in our samples, DNA extraction was carried out using a commercial kit, and a laboratory extraction procedure. PCR amplification was done using 1 set of primers: B4/B5 for Brucella species. Extraction of Brucella DNA using the commercial kit was successful. The laboratory extraction was successful and more economic. A total of 178 peripheral blood specimens were collected from patients with high suspected brucellosis, and 15 samples from animals. When PCR technique was applied to blood samples, 13 cases for patients blood and 9 cases for animals blood, were positive for Brucella species