Air transportation is provided by the movement of aircraft through a network of airports. Researchers have established that approximately 84% of delays are generated at airports. These delays propagate to downstream airports where they are absorbed, passed on or enhanced. Researchers have correlated delays with sets of causal factors and have created models to predict aggregate daily delays at airports. Airport Operation Center (AOC) personnel and Traffic Flow Management (TFM) Specialists have suggested that a model for predicting airport delay in 15 minute epochs would have utility. This paper describes multi-factor models for predicting airport delays in 15 minute epochs at each of the 34 OEP airports. The models are developed using piece-wise linear regressions, using Multi-Adaptive Regression Splines (MARS), for generated delays and for absorbed delays for each of the 34 OEP airports. The models were generated using historic individual airport data. Accuracy evaluation on separate test data shows mean absolute prediction error of 5.3 minutes for generated delay across all the airports, and 2.2 minutes for absorbed delay across all the airports. A summary of the factors that drive the performance of each airport is provided. The implications of these results are discussed.

This paper considers a specially structured uncapacitated facility location problem. We show that several problems, including certain tool selection problems, substitutable inventory problems, supplier sourcing problems, discrete lot sizing problems, and capacity expansion problems, can be formulated as instances of the problem. We also show that the problem with m facilities and n customers can be solved in O(mn), as a shortest path problem on a directed graph.

The road terrain type is important information about a passenger vehicle's surroundings. It suggests an appropriate control algorithm and driving strategy. In this paper, a Lidar sensor is employed to reconstruct the road surface and extract features for terrain classification. The experiment vehicle was driven on four specific road terrains at a variety of speeds. The speed dependency and the effect of using principal component analysis were investigated. The simulation experimental results show that this Lidar sensorbased approach is feasible and robust for passenger vehicles in a range of outdoor scenarios.

Multilateration (MLAT) surveillance is now being used in all types of airspace for air traffic management. MLAT can be used for airport surface movement surveillance as well as for terminal and en route surveillance, using Wide Area Multilateration (WAM). MLAT is a low-cost technology that not only has major advantages in operations and maintenance, but also provides excellent performance under all conditions, especially for countries with large geographic areas or mountainous terrain to cover. This paper focuses on performance metrics from operational system data to demonstrate that the performance of Era's MLAT systems meet surveillance requirements for all surveillance applications. This includes the key performance requirements for the various surveillance applications that are evaluated, including accuracy, coverage, update rate, integrity and availability.

Diffractive optical elements (DOEs) are widely used to realize special diffraction fields today, but the size of the effective Fresnel diffraction field of the DOEs with plane wave incidence is limited by the wavelength of the incident beam, sampling interval of the DOE, and distance between the DOE and the output plane. In this paper, a method is proposed to extend the size of the effective Fresnel diffraction field with an introduced intermediate plane and two-step diffraction calculation. Zero padding is used on the DOE plane, the sampling interval on the intermediate plane is correspondingly decreased, and the size of the Fresnel diffraction field on the output plane is finally extended. The accompanying aliasing is eliminated by placing a low-pass filter on the intermediate plane. Both numerical simulations and experimental results show the validity of the proposed method to extend the size of the effective Fresnel diffraction field of the DOEs with plane wave incidence.