An investigation into flow mode transition and pressure fluctuations for fluidized dense-phase pneumatic conveying of fine powders

This paper presents the results of an ongoing investigation into the fluctuations of pressure signals due to solids-gas flows for dense-phase pneumatic conveying of fine powders.Pressure signals were obtained from pressure transducers installed along different locations of a pipeline for the fluidized dense-phase pneumatic conveying of fly ash(median particle diameter 30μm;particle density 2300kg/m~3;loosepoured bulk density 700kg/m~3) and white powder(median particle diameter 55 u.m;particle density1600kg/m~3;loose-poured bulk density 620kg/m~3) from dilute to fluidized dense-phase.Standard deviation and Shannon entropy were employed to investigate the pressure signal fluctuations.It was found that there is an increase in the values of Shannon entropy and standard deviation for both of the products along the flow direction through the straight pipe sections.However,both the Shannon entropy and standard deviation values tend to decrease after the flow through bend(s).This result could be attributed to the deceleration of particles while flowing through the bends,resulting in dampened particle fluctuation and turbulence.Lower values of Shannon entropy in the early parts of the pipeline could be due to the non-suspension nature of flow(dense-phase),i.e.,there is a higher probability that the particles are concentrated toward the bottom of pipe,compared with dilute-phase or suspension flow(high velocity),where the particles could be expected to be distributed homogenously throughout the pipe bore(as the flow is in suspension).Changes in straight-pipe pneumatic conveying characteristics along the flow direction also indicate a change in the flow regime along the flow.     

Holographic Image Denoising using Random Laser Illumination

In holographic applications, coherent lasers are indispensable source of illumination. Despite high intensity from coherent light sources, they fail in full-field image projection and illustrate speckle images due to high spatial coherence. This article demonstrates speckle-free high contrast computer-generated holographic image projection upon illumination with a perovskite–polystyrene 10 wt%-based random laser. Solvent-engineered efficient and durable perovskite and perovskite–polystyrene 10 wt%-based random lasers are fabricated. Optical characterizations are elucidated and controlled coherence random lasing operation is achieved under room temperature upon addition of polystyrene concentration 10 wt% on perovskite thin film. The addition of 10 wt% polystyrene concentration results in a low far-field divergence angle of ≈10⁰. The controlled coherence in random lasers is necessary to produce a stable interference pattern and to retain the depth of field in holograms. Additionally, the holographic image projection using random lasers reduces diffraction noise, and exhibits high spatial resolution with full-field imaging. Moreover, this study is clear evidence of an effective strategy to achieve high-performance, indigenous designed-controlled coherence in disordered random lasing media and its application to novel holographic image projection.     

Conversion of nuclear to 2-flavour quark matter in rotating compact stars: A general relativistic perspective

The conversion of neutron star to strange star is argued to be a two step process. The first process involves the deconfinement of nuclear to two-flavour quark matter. The GR results shows that the propagating front breaks up into fragments which propagate with different velocities along different directions. The time taken for this conversion to happen is of the order of few ms. This calculation indicates the inadequacy of non-relativistic (NR) or even Special Relativistic (SR) treatments for these cases.     

Isolation of a Diylide‐Stabilized Stannylene and Germylene: Enhanced Donor Strength through Coplanar Lone Pair Alignment

The preparation of the first stable diylide‐substituted stannylene and germylene ( Y₂E, with E=Ge, Sn and Y=[PPh₃‐C‐SO₂Tol]^?) is reported. The synthesis is easily accomplished in one step from the sulfonyl‐substituted metalated ylide YNa and the corresponding ECl₂ precursors. Y₂Ge and Y₂Sn exhibit unusual structures in the solid state and in solution, in which the three adjacent lone pairs in the C‐E‐C linkage are arranged coplanar to each other. As shown by DFT studies, this bonding situation is preferred over the typical π‐donation from the ligands into the empty p‐orbital at the metal due to the strong anion‐stabilizing ability of the sulfonyl groups in the ylide backbone and their additional coordination to the metal. The alignment of the three lone pairs leads to a remarkable boost of the HOMO energy and thus of the donor strengths of the tetrylenes. Hence, Y₂Ge and Y₂Sn become stronger donors than their diamino or diaryl congeners and comparable to cyclic alkyl(amino)carbenes. First reactivity studies confirm the high reactivity of Y₂Ge and Y₂Sn , which for example undergo an intramolecular C?H activation reaction via metal–ligand cooperation.     

Ultrafast Raman loss spectroscopy

This paper deals with a new form of nonlinear Raman spectroscopy called ‘ultrafast Raman loss spectroscopy (URLS)’. URLS is analogous to stimulated Raman spectroscopy (SRS) but is much more sensitive than SRS. The signals are background (noise) free unlike in coherent anti‐Stokes Raman spectroscopy (CARS) and it provides natural fluorescence rejection, which is a major problem in Raman spectroscopy. In addition, being a self‐phase matching process, the URLS experiment is much easier than CARS, which requires specific phase matching of the laser pulses. URLS is expected to be alternative if not competitive to CARS microscopy, which has become a popular technique in applications to materials, biology and medicine. Copyright © 2009 John Wiley & Sons, Ltd.     

The vibrational assignment of phenanthridine molecule based on normal coordinate analysis and DFT

A complete vibrational assignment of phenanthridine C13NH9 has been presented. The infrared (IR) and the Raman spectra of the molecule are analyzed with the help of theoretical prediction of the normal vibrational wavenumbers estimated from normal coordinate analysis (NCA) and density functional theory (DFT) calculations. A general valence force field (GVFF) including 31 parameters (13 diagonal and 18 off‐diagonal) reproduces satisfactorily the in‐plane vibrational signatures of the aforesaid molecule and as well as those for the other related hydrocarbons [phenanthrene and benzo(c)cinnoline]. The bivariate and multivariate data analysis reveals that calculated wavenumbers using GVFF are more accurate than the DFT result. However, DFT yields the relative Raman intensities, which are in good agreement with the experimental ones. The decomposition of the normal mode frequencies into those related to different internal coordinates is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Strong pionic intermittency in ‘cold’ events in12C-AgBr interactions at 4.5 A GeV

In this paper intermittent behaviour of the pions from ‘cold’ and ‘hot’ classes of events from¹²C-AgBr interactions at 4.5 A GeV has been studied, separately. The results reveal strong intermittent pattern in case of ‘cold’ class of events.     

Velocity contours by speckle photography

We describe a method of generating velocity contours of an object using speckle photography. The object is illuminated by a series of laser pulses following each other at equal intervals. A speckle record of the object is observed in a spatial filtering setup with a small aperture in the frequency plane. A fringe pattern representing a map of velocity contours is obtained in the output plane.     

Multiplexing with an extended broad-band source

Carrier-frequency photography in incoherent light can be employed for storing a number of real amplitude objects on a single photographic plate. The objects are placed, successively in contact with a grid and a frequency-plane mask selects two different spectral orders for each object. Different intensity distributions modulate different fringe systems in the image plane and can be retrieved with appropriate filters.     

Amplified backward scattering in LiNbO3:Fe

We study the characteristics of the amplified back-scattered light in a LiNbO₃:Fe crystal cut normal to the optic axis when it is illuminated with a linearly polarized parallel beam of monochromatic light. The scattered light forms different patterns depending on the direction of vibration of the incident beam. The incident beam and the back-scattered beams interfere and generate numerous ‘noisy’ gratings in the volume of the crystal which diffract and amplify selectivity the weak scattered beams. This study is of practical importance since a normally cut LiNbO₃:Fe crystal may be used as a self-starting non-linear adaptive mirror in laser cavities.