Autonomous rendezvous targeting techniques for national launch system application

The rendezvous targeting techniques that can be utilized to achieve autonomous guidance for delivering a cargo to Space Station Freedom (SSF) using the National Launch System's (NLS) Heavy Lift Launch Vehicle (HLLV) and the on-orbit Cargo Transfer Vehicle (CTV) are described. This capability is made possible by advancements in autonomous navigation (Global Positioning System - GPS) on-board the CTV and SSF as well as the new generation flight computers. How the HLLV launch window can be decoupled from the CTV phasing window is described. The performance trades that have to be made to determine the length of the launch window and the phasing window between the CTV and SSF are identified and recommendations made that affect mission timelines

Measurement of Airborne Radionuclides and Their Relation to Weather Patterns at Orono, ME

7Be and 210Pb activities were measured in air sampling filters collected at The University of Maine campus from 2014 to 2019. The activities of 7Be were in the range of 1.178-98.8 Bq, with an average value of 32.13 Bq. The activities of 210Pb were in the range of 0.091 to 13.64 Bq, and an average value of 3.029 Bq. The distributions of activity for both radionuclides are lognormal. Both 7Be and 210Pb show seasonal variation with maximum values in the summer and minimum values in the fall, and the 7Be/210Pb ratio shows a clear seasonal variation with maxima in the spring and summer and minima in the winter. The measured activities of the two radionuclides are correlated (R=0.593, P These results are compared with a sample of results from the literature, selected for similar latitude, showing consistency with some sampling sites in Europe, notably those with some influence from both oceanic and continental air flows. The likely mechanism for the seasonal variation in both radionuclides is increased atmospheric mixing in the warmer months, although a possible explanation for the variation in 7Be/210Pb ratio is influx of oceanic air at the sampling site during the spring. Further research includes correlating the 7Be data with the 11-year solar cycle and adjusting for its effects, and a more detailed analysis and classification of air flows arriving at the sampling site, and correlation between different air masses (oceanic versus continental, for example) and the measured radionuclide activities

Farmland Prices

land, price, Ontario, Canada, Agricultural and Food Policy, Agricultural Finance, Demand and Price Analysis, Land Economics/Use,

A Note on the Economy of Qualities: Attributing Production Practices to Agricultural Practices

Agricultural products are valued for many attributes including those that describe production practices. These production attributes are established through public and private efforts to promulgate standards and labels that differentiate products based on labor treatment, environmental impact, animal welfare, and other practices that occur during production. Organizations, like third-party certifiers, coordinate information and give credence to products in a way that enables consumers to differentiate products by production practices. Libertarian and utilitarian arguments may be used in the normative debate surrounding the appropriate role of government in sponsoring standards and labels that inform consumers about the modes of production

Long Cavity Laser Excitation and Digital Filtering of Narrowband Ultrasound for Enhanced Signal-to-Noise Ratio

In recent years numerous efforts have addressed the substitution of laser-based ultrasonic testing techniques for conventional piezoelectric transducers in demanding applications where contact with the specimen surface is impractical [1]. Ultrasonic signals are typically generated by pulsed laser irradiation of the sample surface [2] and detected by some sort of heterodyne, Fabry-Perot, or path-stabilized Michelson interferometer [3]. While optical methods for generation and detection of ultrasound have performed quite satisfactorily under controlled laboratory conditions, similar success in more demanding industrial environments has proven elusive because the optical techniques suffer limitations with regard to generation efficiency and detection sensitivity. For laser ultrasonics to play a greater role in industrial NDE and on-line process control, substantial improvement in overall system sensitivity must be realized.</p