Holographic interferometric investigation of shock wave interaction with a ramp

The internal flowfield including shock reflections structure inside a 2-D half inlet model was examined by a double exposure holographic interferometry using a Q-switched pulse laser. The interferograms give detailed flow visualization pictures. The structures of regular reflection, lambda reflection and Mach reflection in the inlet channel were observed. From the analysis of fringe patterns, the quantitative distributions of flow density, pressure and Mach number of the internal flowfield have been reconstructed. The boundary layer thickening and separation in the case of lambda reflection and the Mach stem in the case of Mach reflection were clearly demonstrated in the holographic fringe patterns. The results show that the shock interacitons with the ramp and the wall introduce a complicated flow structure which could strongly affect the efficiency of the inlet.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Digital phase shift holographic interferometry and its application in the experimental flow study

The application of digital phase shift holographic interferometry to flow-visualization and flow temperature measurement of a 2D thermal flow field was experimentally investigated. An improved recording system for two reference beam phase shift holographic interferometry is set up for this experiment, and details of this experimental technique are described. The phase distribution obtained by this technique presents an excellent picture of flow visualization. From this phase image, temperature distribution of the 2D thermal flow field is also calculated and compared with some measured values obtained using thermocouple probes.     

Globally optimal superconducting magnets part II: symmetric MSE coil arrangement

A globally optimal superconducting magnet coil design procedure based on the Minimum Stored Energy (MSE) current density map is outlined. The method has the ability to arrange coils in a manner that generates a strong and homogeneous axial magnetic field over a predefined region, and ensures the stray field external to the assembly and peak magnetic field at the wires are in acceptable ranges. The outlined strategy of allocating coils within a given domain suggests that coils should be placed around the perimeter of the domain with adjacent coils possessing alternating winding directions for optimum performance. The underlying current density maps from which the coils themselves are derived are unique, and optimized to possess minimal stored energy. Therefore, the method produces magnet designs with the lowest possible overall stored energy. Optimal coil layouts are provided for unshielded and shielded short bore symmetric superconducting magnets.     

Homogenization of Solute Transport in Unsaturated Double-Porosity Media: Model and Numerical Validation

Transport in Porous Media - The development of a macroscopic model for solute transport coupled with unsaturated water flow in double-porosity media is presented in this work, by using the...     

Globally optimal superconducting magnets part I: minimum stored energy (MSE) current density map

Accurate determination of ¹H NMR signal intensities is useful for quantitative analysis of the hydrogen content and also to determine the relative peak intensity ratios in different application scenarios. To this end we have investigated the reliability and sources of intensity errors in ¹H solid-state MAS NMR. If sufficient resolution can be achieved by very high spinning speeds and high magnetic fields, quantification is straight forward. However, for poorly resolved spectra we show that small phase errors add a considerable amount of uncertainty. An analytical expression for the phase induced intensity-errors allowed us to suggest a robust and reliable recipe which is based on a combination of the spin-echo experiment, an extrapolation technique and a deconvolution algorithm which includes fitting of the signal phase. It significantly reduces errors caused by phase distortions, homonuclear dipolar dephasing, the receiver dead time delay and baseline rolling. The method was validated experimentally on samples with strong homonuclear dipolar interactions.     

In vitro assessment of pediococci- and lactobacilli-induced cholesterol-lowering effect using digitally enhanced high-performance thin-layer chromatography and confocal microscopy

The cholesterol-lowering properties of 12 lactic acid bacteria (LAB) in the absence or presence of 0.3% bile salts were assessed and compared quantitatively and qualitatively in vitro. A new, more sensitive and cost-effective high-performance thin-layer chromatography method combined with digital image evaluation of derivatised chromatographic plates was developed and validated to quantify cholesterol in LAB culture media. The performance of the method was compared with that of the o-phthalaldehyde method. For qualitative assessment, assimilated fluorescently tagged cholesterol was visualised by confocal microscopy. All LAB strains exhibited a cholesterol-lowering effect of various degrees (19–59% in the absence and 14–69% in the presence of bile salts). Lactobacillus plantarum LAB12 and Pentosaceus pentosaceus LAB6 were the two best strains of lactobacilli and pediococci. They lowered cholesterol levels by 59% and 54%, respectively, in the absence and by 69% and 58%, respectively, in the presence of bile salts. Confocal microscopy showed that cholesterol was localised at the outermost cell membranes of LAB12 and LAB6. The present findings warrant in-depth in vivo study.

(A) 3D plots based on scan at 525 nm of (B) derivatized HPTLC plate of separated cholesterol and (C) confocal microscopic image showing the localisation of NBD-cholesterol assimilated by LAB

     

Nucleation and fractal growth of zirconium oxo-alkoxy nanoparticles at the induction stage of sol–gel process

Monodispersed zirconium oxo-alkoxy nanoparticles are synthesized via a sol?Cgel method in a rapid micromixing reactor with in situ particle size measurements. The nucleated nanoparticles of 4.7?nm diameter are free from impurities and conserve high chemical activity. They can be associated in 1D fractals. These nanoparticles can form high optical-quality coatings on hydrophilic substrates.     

Holographic tomography by SART and it's application to reconstruction of 3D temperature distribution

Application of holographic tomography to reconstruction of 3D asymmetric temperature distribution is experimentally and numerically investigated. A new simultaneous algebraic reconstruction technique (SART) code for holographic tomography is presented. Important features of SART for reconstruction of temperature field were evaluated using numerical model functions. Data from diffuse-illumination holographic interferograms obtained at twenty different view directions and with 40° range of view angles were used to reconstruct a 3D thermal flow field by SART method. An average reconstruction error of about 5% is estimated. The ability to reconstruct the 3D field using a limited viewing range implies that SART is especially suitable for the holographic tomography of aerodynamic density field.

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Holografische Tomographie mit Simultaneous Algebraic Reconstruction Technik (SART) und ihre Anwendung zur Rekonstruktion von 3-dimensionalen Temperaturverteilungen

Zusammenfassung Die Anwendung der holografischen Tomographie zur Rekonstruktion von 3-dimensionalen asymetrischen Temperaturverteilungen wird experimentiell und numerisch untersucht. Eine neue simultane algebraische Rekonstruktionstechnik (SART) für holografische Tomographie wird beschrieben. Wichtige Eigenschaften der SART zur Rekonstruktion von Temperaturfeldern wurden unter Verwendung numerischer Modellfunktionen ausgewertet. Die numerische Analyse zeigt, daß die SART eine zuverlässigere, stabilere und wirksamere Methode zur holografischen Tomographie bietet.Die Daten von holografischen Interferogrammen mit diffuser Beleuchtung, die aus zwanzig verschiedenen Beobachtungsrichtungen und innerhalb eines Beobachtungswinkels von 40° erhalten wurden, dienten zur Rekonstruktion eines 3-dimensionalen Temperaturfeldes mit der SART-Methode. Der durchschnittliche Rekonstruktionsfehler wird mit 5% geschätzt. Die Fähigkeit 3-dimensionale Felder mit beschränkten Beobachtungswinkeln zu rekonstruieren weist die besondere Fähigkeit des SART für die holografische Tomographie von aerodynamischen Dichtefeldern nach.