Analysis of Risk-Based Operational Bird Strike Prevention

Bird strike prevention in civil aviation has traditionally focused on the airport perimeter. Since the risk of especially damaging bird strikes outside the airport boundaries is rising, this paper investigates the safety potential of operational bird strike prevention involving pilots and controllers. In such a concept, controllers would be equipped with a bird strike advisory system, allowing them to delay departures which are most vulnerable to the consequences of bird strikes in case of high bird strike risk. An initial study has shown the strong potential of the concept to prevent bird strikes in case of perfect bird movement prediction. This paper takes the research to the next level by taking into account the limited predictability of bird tracks. As such, the collision avoidance algorithm is extended to a bird strike risk algorithm. The risk of bird strikes is calculated for birds expected to cross the extended runway center line and to cause aircraft damage upon impact. By specifically targeting these birds and excluding birds lingering on the runway which are taken care of by the local wildlife control, capacity reductions should be limited, and the implementation remain feasible. The extrapolation of bird tracks is performed by simple linear regression based on the bird positions known at the intended take-off times. To calculate the probability of collision, uncertainties resulting from variability in bird velocity and track are included. The study demonstrates the necessity to limit alerts to potentially damaging strikes with birds crossing the extended runway center line to keep the imposed delays tolerable for airports operating at their capacity limits. It is shown that predicting bird movements based on simple linear regression without considering individual bird behavior is insufficient to achieve a safety-effect. Hence, in-depth studies of multi-year bird data to develop bird behavior models and reliable predictions are recommended for future research. This is expected to facilitate the implementation of a bird strike advisory system satisfying both safety and capacity aspects.

Guo Zhongshu's Archaeology of Writing

“Bird-tracks” and “tadpoles” are both names for ancient script. As customs changed, the script came to be used less and less, until any basis for knowledgeable discussion was lost and it was known only from hearsay. The Grand Preceptor said: “When the [forms of the] rites are lost, search for them in the countryside.” Might not ancient script be even better than the countryside?The names of dozens of artists from the tenth century have come down to us, for the most part with very little information about their lives and scarcely more about their art. Fortunately, the life and professional career of Guo Zhongshu 郭忠恕 (928–977) can be reconstructed in enough detail to give a sense of the personality of the artist and the world that he experienced. Indeed, we are doubly fortunate because Guo, it turns out, had no ordinary life. Known to art historians today primarily as one of the great painters of architectural subjects in Chinese history, Guo entered adult life in a different guise, as a brilliant young paleographer and calligrapher. This aspect of his career, no less important than his painting, is the subject of the present study. Although specialists have recognized his scholarly and calligraphic achievements, we still lack a contextualized account that incorporates what can be known of his biography and social circumstances. More important for the theme of this special issue, the material dimension of Guo's paleographic and calligraphic activities also remains to be explored. Any discussion can only be very partial, however, since no manuscripts or autograph calligraphies survive, only stone steles; fortunately, Guo's engagement with stele production is in itself of the highest historical interest. The chronologically organized text that follows tells a biographical story, with as much detail as the available sources allow, which eventually opens out onto the material world of steles, before returning to biography to recount the last chapter of Guo Zongshu's life. Rather than offering a conclusion, I end with a reflection on the materialities of transmission of paleographic and calligraphic knowledge. For the purposes of this article I have not thought it necessary to choose between the very different lenses of biography and material culture, since my goal is not to prove a thesis but to reconstruct an unfamiliar world. As I hope to show, the understanding of one person's life can enrich the understanding of artifacts associated directly and indirectly with the person, and vice versa.

ROLE OF ICHNOLOGY IN THE HISTORY OF PHOTOGRAPHY

ABSTRACT Vertebrate ichnology in North America has a long and distinguished history, starting with the remarkable discoveries by Edward Hitchcock of dinosaur footprints and trackways in the Connecticut River Valley. Hitchcock assembled a unique collection that is currently housed in the Beneski Museum of Natural History, Amherst College, and his work essentially constituted the beginnings of ichnology as a viable sub-discipline of paleontology. Although his original interpretation that these Late Triassic locomotion traces were bird tracks was incorrect, he indirectly linked birds and dinosaurs. Other talented amateurs including John Collins Warren, James Deane, Dexter Marsh and Roswell Field worked on these track sites and some were prolific authors. Three major books have significance, Dr. John Collins Warren published his book Remarks on Some Fossil Impressions in the Sandstone Rocks of Connecticut River in 1854 making it the second book ever published exclusively on ichnology and the second American publication (and first American scientific publication) to be illustrated with a photograph, a salt print, used as the frontispiece depicting what he interpreted as the fossilized tracks of prehistoric birds. James Deane published a book in 1861entitled Ichnographs from the Sandstone of Connecticut River containing photographs and etchings. Finally, Edward Hitchcock published The Supplement to the Ichnology of New England in 1865 that contained seven albumen prints by the professional photographer J. Lovell of Amherst. These volumes pioneered the use of photography in American scientific publications.