Modeling of time-resolved laser-induced incandescence transients for particle sizing in high-pressure spray combustion environments: a comparative study

In this study experimental single-pulse, time-resolved laser-induced incandescence (TIRE-LII) signal intensity profiles acquired during transient Diesel combustion events at high pressure were processed. Experiments were performed between 0.6 and 7MPa using a high-temperature high-pressure constant volume cell and a heavy-duty Diesel engine, respectively. Three currently available LII sub-model functions were investigated in their performance for extracting ensemble mean soot particle diameters using a least-squares fitting routine, and a "quick-fit” interpolation approach, respectively. In the calculations a particle size distribution as well as the temporal and spatial intensity profile of the heating laser was taken into account. For the poorly characterized sample environments of this work, some deficiencies in these state-of-the-art data evaluation procedures were revealed. Depending on the implemented model function, significant differences in the extracted particle size parameters are apparent. We also observe that the obtained "best-fit” size parameters in the fitting procedure are biased by the choice of their respective "first-guess” initial values. This behavior may be caused by the smooth temporal profile of the LII cooling curve, giving rise to shallow local minima on the multi-parameter least squares residuals, surface sampled during the regression analysis procedure. Knowledge of the gas phase temperature of the probed medium is considered important for obtaining unbiased size parameter information from TIRE-LII measurement

Limitations: The Centerpiece of Copyright in Distress - An Introduction

After the exclusive rights in copyright have been consolidated in a century-long historical development, limitations and exceptions have become the main instrument to determine the exact scope of copyright. Limitations and exceptions do not merely fine-tune copyright protection. Rather, they balance the interests of authors, rightholders, competitors and end-users in a quadrupolar copyright system. Understanding this is of particular importance in the digital and networked information society, where copyrighted information is not only created and consumed, but constantly extracted, regrouped, repackaged, recombined, abstracted and interpreted. However, serious doubts exist whether the present, historically grown system of limitations adequately balances the interests involved in the information society. Both the closed list of limitations allowed under Art. 5 of the EU Information Society Directive 2001/29/EC and a narrowly interpreted three-step test contained in Arts. 13 TRIPS and 5 (5) of the Information Society Directive appear as obstacles in the way of achieving the appropriate balance needed. This brief article outlines the issues involved which were discussed at the International Conference on “Commons, Users, Service Providers – Internet (Self-) Regulation and Copyright” which took place in Hannover, Germany, on 17/18 March 2010 on the occasion of the launch of JIPITEC

Optical diagnostics of diesel spray injections and combustion in a high-pressure high-temperature cell

We report on spatially and temporally resolved optical diagnostic measurements of propagation and combustion of diesel sprays introduced through a single-hole fuel injector into a constant volume, high-temperature, high-pressure cell. From shadowgraphy images in non-reacting environments of pure nitrogen, penetration lengths and dispersion angles were determined for non-vaporizing and vaporizing conditions, and found to be in reasonable agreement with standard models for liquid jet propagation and break-up. Quasi-simultaneous two-dimensional images were obtained of laser elastic light scattering, shadowgraphs and spectrally integrated flame emission in a reacting environment (cell temperature 850 K). In addition laser-induced incandescence was employed for the identification of soot-loaded regions. The simultaneously recorded spray images exhibit remarkable structural similarity and provide complementary information about the spray propagation and combustion process. The measurements also reveal the fuel vapor cloud extending well beyond the liquid core and close to the nozzle tip. Ignition takes place close to the tip of the spray within the mixing layer of fuel vapor and surrounding air. Soot is formed in the vapor core region at the tip of the liquid fuel jet. Our results support recently developed phenomenological model on diesel spray combustio

OO(1 kHz) In-Lab X-ray Particle Velocimetry for Multiphase Flows

We combine X-ray-specific tracer particles, a photon counting detector, and a liquid metal anode X-ray source to achieve $O$(1 kHz) X-ray imaging speeds in the laboratory, 15$\times$ faster than previous comparable studies. To demonstrate the capabilities of these imaging speeds, we conduct three experiments: 2D and 3D X-ray particle tracking velocimetry (XPTV) of Poiseuille pipe flow, 3D XPTV of flow around a Taylor bubble, and 3D scalar mixing with a laminar jet. These experiments demonstrate the performance improvement of combining the aforementioned elements, the applicability to multiphase flows and deforming systems, and the potential to capture scalar and vector quantities simultaneously. Most importantly, these experiments are conducted in the laboratory, showing that in-lab X-ray particle velocimetry techniques are now usable for a wider range of flows of interest

Author Correction: Enhanced tenacity of mycobacterial aerosols from necrotic neutrophils

The original version of this Article contained errors within the affiliations section. Affiliation 4 was incorrectly given as ‘Leibniz Research Alliance INFECTIONS’21, Leipzig, Germany’. The correct affiliation is listed below: Leibniz Research Alliance INFECTIONS’21, Borstel, 23845, Germany Also, Affiliation 5 was incorrectly given as ‘German Center for Infection Research, TTU-TB, Borstel, 23845, Germany’. The correct affiliation is listed below: German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel, Germany. Finally, the original HTML version of this Article omitted an affiliation for G. Gabriel. The correct affiliations for G. Gabriel are listed below: Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, 20251, Germany. Leibniz Research Alliance INFECTIONS’21, Borstel, 23845, Germany. German Center for Infection Research (DZIF), Partner Site Hamburg-Lübeck-Borstel, Germany. These errors have now been corrected in the PDF and HTML versions of the Article

Enhanced tenacity of mycobacterial aerosols from necrotic neutrophils

The tuberculosis agent Mycobacterium tuberculosis is primarily transmitted through air, but little is known about the tenacity of mycobacterium-containing aerosols derived from either suspensions or infected neutrophils. Analysis of mycobacterial aerosol particles generated from bacterial suspensions revealed an average aerodynamic diameter and mass density that may allow distant airborne transmission. The volume and mass of mycobacterial aerosol particles increased with elevated relative humidity. To more closely mimic aerosol formation that occurs in active TB patients, aerosols from mycobacterium-infected neutrophils were analysed. Mycobacterium-infected intact neutrophils showed a smaller particle size distribution and lower viability than free mycobacteria. In contrast, mycobacterium-infected necrotic neutrophils, predominant in M. tuberculosis infection, revealed particle sizes and viability rates similar to those found for free mycobacteria, but in addition, larger aggregates of viable mycobacteria were observed. Therefore, mycobacteria are shielded from environmental stresses in multibacillary aggregates generated from necrotic neutrophils, which allows improved tenacity but emphasizes short distance transmission between close contacts

Two-Dimensional Laser Diagnostics and Modeling of Counterflow Diffusion Flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86756/1/Sick51.pd