Wind and Fire Coupled Modelling—Part I: Literature Review

Wind and fire phenomena can together be a devastating force, whether in the case of a building fire, release of smoke in an urban area or forest fire near an urban habitat. Most of the fire phenomena are influenced by the wind, usually for the worse. If we want to understand fires, we have to understand wind as well, and model it appropriately. This modelling is described by the discipline of Computational Wind Engineering, from which we are able to transfer invaluable knowledge to coupled wind-fire analyses. This two-part review is dedicated to such a transfer. In Part I, the authors describe the historical and most current instances of wind and fire coupled modelling, referred to as simple models, in situ measurements, wind tunnel experiments or numerical studies with CFD. The review is subdivided into six categories, namely flame behaviour in wind conditions, indoor flows, natural smoke ventilators, tunnel ventilation, wildfires and firebrand transport, and urban dispersion of smoke. Besides flame behaviour, all remaining topics are covered, to the best of the authors’ knowledge, with multiple references to valuable experimental and numerical studies. In Part II of the review, the authors describe the best practices of Computational Wind Engineering, that may be transferred to fire-oriented numerical studies. This part provides good practice guidelines, reference studies and a proposal for the optimisation of the simulation procedure for coupled wind and fire models.     

High-performance inverted top-emitting green electrophosphorescent organic light-emitting diodes with a modified top Ag anode

Green electrophosphorescent inverted top-emitting organic light-emitting diodes with a Ag/1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) anode are demonstrated. A high current efficacy of 124.7 cd/A is achieved at a luminance of 100 cd/m² when an optical outcoupling layer of N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl-4,4′-diamine (α-NPD) is deposited on the anode. The devices have a low turn-on voltage of 3.0 V and exhibit low current efficacy roll-off through luminance values up to 10,000 cd/m². The angle dependent spectra show deviation from Lambertian emission and color change with viewing angle. Hole-dominated devices with Ag/HAT-CN electrodes show current densities up to three orders of magnitude higher than devices without HAT-CN.     

Evaluation of the effectiveness of the fire retardant mixture containing potassium carbonate using a cone calorimeter

This article presents the results of investigations obtained for a wood fire retardant agent which is currently under production. Experiments were conducted using a mixture of potassium carbonate and urea in accordance with the PN‐C‐04914 standard (the Polish equivalent of ISO 5660‐1). Wood samples of Scots pine (Pinus sylvestris L.) were treated with the above mixture as well as with its individual components. It was observed that impregnation of samples with potassium carbonate and a mixture of potassium carbonate and urea has an advantageous influence on the reduction of the heat release and the heat of combustion, and also prolongs the time to ignition. Urea alone failed to exert a fire‐retardant effect on wood samples. Copyright © 2011 John Wiley & Sons, Ltd.     

Degenerate Quantum Gases in Microgravity

Clouds of ultra-cold atoms and especially Bose–Einstein condensates (BEC) provide a source for coherent matter-waves in numerous earth bound experiments. Analogous to optical interferometry, matter-wave interferometers can be used for precision measurements allowing for a sensitivity orders of magnitude above their optical counterparts. However, in some respects the presence of gravitational forces in the lab limits experimental possibilities. In this article, we report about a compact and robust experiment generating Bose–Einstein condensates in the drop tower facility in Bremen, Germany. We also present the progress of building the succeeding experiment in which a two species atom interferometer will be implemented to test the weak equivalence principle with quantum matter.     

Control of Underactuated Skid Steering Mobile Platforms Based on Extended Factitious Force Concept

In the paper new control method of skid steering mobile platforms has been presented. Such platforms are robotic objects with deficit of control inputs in dynamic model, i.e. they are dynamically under-actuated. To compensate lack of controls, it has been assumed that there are additional factitious inputs to dynamics (so-called factitious forces), which preserve possibility to control dynamical model of skid steering mobile platform, expressed in auxiliary velocities. Factitious inputs do not exist in reality therefore it was assumed that they are equal to zero equivalently. Signals calculated from implicit functions defining factitious forces make possible to approximate slipping effects and they can be taken into account by construction of control law.     

The effect of high temperature heat treatment on the structure and properties of anodic aluminum oxide

Nanoporous anodic aluminum oxide (AAO) membranes can be fabricated with highly controllable thickness and porosity, making them ideal for filtration applications. Use of these membranes is currently limited largely due to their size and overall fragility. The objective of this research was to improve mechanical properties of AAO membranes through use of high temperature heat treatment to induce phase transformations in the material. A repeatable two-step anodization process was developed for consistent sample fabrication and heat treatments were performed at 900 °C and 1200 °C in air. The pore morphology and phase composition of the as-anodized and heat-treated membranes were then observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness testing was utilized to evaluate the mechanical behavior of the membranes before and after heat treatment. As-anodized AAO membranes were determined to be amorphous, and membranes heat-treated to 900 °C and 1200 °C were transformed to crystalline phases while retaining their original porous structure. Heat treatment to 900 °C resulted in formation of the γ-alumina transition phase in the skeleton regions of the membrane and nanocrystalline regions of α-alumina throughout the structure, while heat treatment to 1200 °C completely transformed the material to the stable α-alumina structure. The microhardness testing showed an increase in hardness from 2.5 ± 0.4 GPa to 4.7 ± 1.0 GPa in the transformation from amorphous to α-alumina.