Assessing the feasibility of fly based surveillance of wildlife infectious diseases

Monitoring wildlife infectious agents requires acquiring samples suitable for analyses, which is often logistically demanding. A possible alternative to invasive or non-invasive sampling of wild-living vertebrates is the use of vertebrate material contained in invertebrates feeding on them, their feces, or their remains. Carrion flies have been shown to contain vertebrate DNA; here we investigate whether they might also be suitable for wildlife pathogen detection. We collected 498 flies in Taï National Park, Côte d’Ivoire, a tropical rainforest and examined them for adenoviruses (family Adenoviridae), whose DNA is frequently shed in feces of local mammals. Adenoviral DNA was detected in 6/142 mammal-positive flies. Phylogenetic analyses revealed that five of these sequences were closely related to sequences obtained from local non-human primates, while the sixth sequence was closely related to a murine adenovirus. Next-generation sequencing-based DNA-profiling of the meals of the respective flies identified putative hosts that were a good fit to those suggested by adenoviral sequence affinities. We conclude that, while characterizing the genetic diversity of wildlife infectious agents through fly-based monitoring may not be cost-efficient, this method could probably be used to detect the genetic material of wildlife infectious agents causing wildlife mass mortality in pristine areas

Selected applications of planar imaging velocimetry in combustion test facilities

The contribution provides an overview on the applicability of particle image velocimetry (PIV) and Doppler global velocimetry (DGV) in combustion test facilities and summarizes experiences gained in a number of applications that were performed in the past 6 years. Emphasis is placed on the experimental aspects of each application rather than the interpretation of the acquired flow field data because many of the encountered problems and chosen solution strategies are unique to this area of planar velocimetry application. In particular imaging configurations, seeding techniques, data acquisition strategies as well as pre- and post-processing methodologies are outlined. The paper describes four similar applications of PIV in atmospheric and pressurized combustors containing single burners that are operated either with kerosene or natural gas. Aside from providing adequate optical access to the respective facilities the most challenging issue has been the reliable supply of non-volatile and non-reacting solid particle seeding. Given the rather large mass flows of up to 1 kg/s inside the combustors, sufficient seeding quantities could best be delivered by fluidized bed particle generators, sometimes even operated in parallel. The devices have been continually improved to allow constant delivery rates only during data acquisition periods, thus preventing unnecessary collection of seeding in the facility. The choice and handling of the seeding particle powder was found to be crucial for the overall success of the measurements. The first application describes initial trials on a swirled kerosene spray fuel nozzle at 3 bars and illustrates problems encountered due to flame luminosity as well as strong light scattering from the fuel droplets. The second application summarizes the challenges faced in obtaining phase-resolved, three-component velocity data from a generic atmospheric gas combustor using stereoscopic PIV. A much larger, swirl stabilized gas burner as utilized in stationary power generation was the subject of the third described application. Here a novel methodology of data acquisition and post-processing provides phase resolved velocity maps even of flows that have non-constant oscillation frequencies. Finally, the fourth application describes how the combination of PIV with DGV can yield three-component velocity data in areas of limited optical access using only one viewing window and one separate window (or probe) for light sheet delivery

Development and Application of Laser-Based Diagnostics for Combustion Research at DLR Cologne

Concerned with delivering measurement data from transonic turbomachinery and pressurized combustion facilities alike, the division of Measurement Techniques at the Institute of Propulsion Technology develops and utilizes a wide variety of primarily laser-based diagnostics for velocimetry and spectroscopy. The paper intends to give an overview of the group’s activities highlighting some of the more recent efforts, such as three-component PIV measurements in a full scale gas turbine combustors as well as single line OH-thermometry for planar temperature measurement in lean combustion. Concerning light sources, both a new laser system for unsteady planar Doppler velocimetry as well as low cost illumination sources using high power light-emitting diodes for high speed shadowgraphy and PIV are described

Combined PIV and DGV applied to a pressurized gas turbine combustion facility

The paper provides an overview of flow field measurements on a pressurized generic combustor that shares typical features of realistic gas turbine combustors. Both Doppler global velocimetry (DGV) and particle image velocimetry (PIV) were applied in parallel to achieve volumetric, three-component velocity data sets of the reacting flow field at pressures of 2 and 10 bars with 700 K pre-heating. Limited optical access to the mixing zone required a combination of PIV and DGV to obtain averaged three-component velocity data from a single viewing direction. The final volume data sets of the time-averaged flow in the mixing zone contain about 40 parallel planes spaced at 2 mm with a spatial resolution of 1.2 x 1.2 mm2 each. Difficulties encountered in the application of stereoscopic PIV to a simple atmospheric generic combustor illustrate the advantage of the combined PIV-DGV technique. Furthermore current knowledge on solid particle seeding methods required for reactive flow measurements is presented

Selected applications of planar imaging velocimetry in combustion test facilities

The article provides an overview on the application of particle image velocimetry (PIV) and Doppler global velocimetry (DGV) in combustion test facilities that are operated at pressures of up to 10 bar. Emphasis is placed on the experimental aspects of each application rather than the interpretation of the acquired flow field data because the many of the encountered problems and chosen solution strategies are unique to this area of velocimetry application. In particular imaging configurations, seeding techniques, data acquisition strategies as well as pre- and post-processing methodologies are outlined