Aircraft and ground vehicle friction correlation test results obtained under winter runway conditions during joint FAA/NASA Runway Friction Program

Aircraft and ground vehicle friction data collected during the Joint FAA/NASA Runway Friction Program under winter runway conditions are discussed and test results are summarized. The relationship between the different ground vehicle friction measurements obtained on compacted snow- and ice-covered conditions is defined together with the correlation to aircraft tire friction performance under similar runway conditions

Evaluation of two transport aircraft and several ground test vehicle friction measurements obtained for various runway surface types and conditions. A summary of test results from joint FAA/NASA Runway Friction Program

Tests with specially instrumented NASA Boeing 737 and 727 aircraft together with several different ground friction measuring devices were conducted for a variety of runway surface types and conditions. These tests are part of joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow and ice-covered runway conditions is discussed as well as ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the correlation between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, type and amount of surface contaminant, and ambient temperature are discussed. The effect of surface type on wet friction levels is also evaluated from comparative data collected on grooved and ungrooved concrete and asphalt surfaces

Models for Sortie Generation with Autonomic Logistics

The primary objective of this research is to investigate the impact of an autonomic logistics system (ALS) on the sortie generation process for an individual airbase. As in some prior studies of this process, the methodology used to model the sortie generation process is a queueing network containing fork-join nodes for concurrent maintenance activities. The sortie generation rate is commonly regarded as the primary performance measure of the sortie generation process. This measure coincides with the throughput and is used to compare two models: (1) pre-ALS operations and (2) ALS-enhanced airbase operations. Analysis of the models shows that the ALS model yields higher sortie generation rates under a variety of scenarios resulting from the differences in the sortie generation process that are inherent when an ALS is implemented. These results demonstrate that implementation of an ALS will positively impact the sortie generation process by increased sortie generation rates with equivalent or reduced resource levels

Elastic precursor of the transformation from glycolipid-nanotube to -vesicle

By the combination of optical tweezer manipulation and digital video microscopy, the flexural rigidity of single glycolipid "nano" tubes has been measured below the transition temperature at which the lipid tubules are transformed into vesicles. Consequently, we have found a clear reduction of the rigidity obviously before the transition as temperature increasing. Further experiments of infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) have suggested a microscopic change of the tube walls, synchronizing with the precursory softening of the nanotubes.Comment: 9 pages, 6 figure

Developments in new aircraft tire tread materials

Comparative laboratory and field tests were conducted on experimental and state-of-the-art aircraft tire tread materials in a program aimed at seeking new elastomeric materials which would provide improved aircraft tire tread wear, traction, and blowout resistance in the interests of operational safety and economy. The experimental stock was formulated of natural rubber and amorphous vinyl polybutadiene to provide high thermal-oxidative resistance, a characteristic pursued on the premise that thermal oxidation is involved both in the normal abrasion or wear of tire treads and probably in the chain of events leading to blowout failures. Results from the tests demonstrate that the experimental stock provided better heat buildup (hysteresis) and fatigue properties, at least equal wet and dry traction, and greater wear resistance than the state-of-the-art stock

Arctic Centre: Rovaniemi, Finland

The Arctic Centre, developed in response to the City of Rovaniemi\u27s issuance of an ideas competition, is a complex incorporating two facilities: the Arctic Museum and the Lapland Provincial Museum

European Flight Restrictions May Inhibit International Propagation of Ebola

The rise of aviation as the dominant form of international transportation has increased the potential for the spread of infectious diseases. The 2014 West African Ebola Outbreak is no exception, with localized outbreaks in multiple countries caused by infected individuals traveling by plane. To inhibit the spread of Ebola to the United States it has been suggested that airlines cancel direct inbound flights from the affected region. To examine the effects of this approach, we developed and analyzed an agent-based metapopulation network model to simulate the international flight-based spread of Ebola. A metapopulation network consisting of 3,052 subpopulations connected by 83,295 flights was developed to simulate the transportation and infection of individuals in discrete timesteps of 30 minutes. To simulate the transmission dynamics of Ebola within subpopulations, airports, and flights, we constructed an SEIR model in which individuals are classified as either susceptible, exposed, infectious, or removed. The spread of Ebola was simulated using an R0 of 2.1, as estimated for the 2014 West African Ebola outbreak, and extrapolated to scenarios of unilateral flight restrictions. We tested situations in which the United States, the European Union, or other African nations refused inbound flights. We found that flight restrictions can decrease the number of subpopulations with infectious or exposed individuals, with European-bound flight restrictions decreasing the spread of Ebola by as much as 80%. While flight restrictions may be politically and economically infeasible, our model suggests that the implementation of flight restrictions on European-bound flights may effectively mitigate the international spread of Ebola

On the Informational Comparison of Qualitative Fuzzy Measures

International audienceFuzzy measures or capacities are the most general representation of uncertainty functions. However, this general class has been little explored from the point of view of its information content, when degrees of uncertainty are not supposed to be numerical, and belong to a finite qualitative scale, except in the case of possibility or necessity measures. The thrust of the paper is to define an ordering relation on the set of qualitative capacities expressing the idea that one is more informative than another, in agreement with the possibilistic notion of relative specificity. To this aim, we show that the class of qualitative capacities can be partitioned into equivalence classes of functions containing the same amount of information. They only differ by the underlying epistemic attitude such as pessimism or optimism. A meaningful information ordering between capacities can be defined on the basis of the most pessimistic (resp. optimistic) representatives of their equivalence classes. It is shown that, while qualitative capacities bear strong similarities to belief functions, such an analogy can be misleading when it comes to information content