Continuous prediction of Spartan visibility from Orbiter over modeled free-flight mission

Orbital operations in the neighborhood of other satellites or free-flying objects need the ability to see and detect such objects optically. This ability depends primarily on the brightness of the object relative to other sources present. The present analysis and computational procedure provides a means for predicting the visual brightness of a satellite when viewed from a nearby satellite in the same orbit. It is designed specifically for estimating the brightness of Spartan free-flyers from the STS Orbiters which release and later retrieve them, but the basic methods are applicable to other satellite-to-satellite visibility prediction problems. The Spartan reflector model defined herein is illuminated both by direct solar radiation and by the earth (albedo), producing a model source of defined directional intensity. The intensity in the Orbiter direction (along orbit) yields the desired maximum range directly. The required geometric and photometric calculations involve a number of angles in space, which are readily computed from the basic directions defining their sides. The time-dependent directions are determined by straightforward calculation from fundamental relationships and constants

Propulsion-free separation and rendezvous of small shuttle free-flyers using controlled differential drag

A natural successor in the Shuttle era to many sounding rocket flights is the free-flyer mode of operation, in which the Shuttle Orbiter releases a subsatellite (with payloads), effects a desired separation, and approaches and retrieves the free-layer. The propulsive maneuvers required of the Orbiter by equivalent relative motions obtained through controlled differential drag (via changes in free-layer effective area and/or Orbiter attitude changes) are replaced. Simplified analytical techniques are developed and feasibility is verified

Orbit Selection for Earth Observation Missions

The orbit selection process is simplified for most earth-oriented satellite missions by a restriction to circular orbits, which reduces the primary orbit characteristics to be determined to only two: altitude and inclination. A number of important mission performance characteristics depend on these choices, however, so a major part of the orbit selection task is concerned with developing the correlating relationships in clear and convenient forms to provide a basis for rational orbit selection procedures. The present approach to that task is organized around two major areas of mission performance, orbit plane precession and coverage pattern development, whose dependence on altitude and inclination is delineated graphically in design chart form. These charts provide a visual grasp of the relationships between the quantities cited above, as well as other important mission performance parameters including viewing time of day (solar), sensor swath width (and fields of view), swath sequencing, and pattern repeat condition and repeat periods

The management of deshopping and its effects on services: a mass market case study

Purpose: Deshopping is the return of products, after they have fulfilled the purpose for which they were borrowed. Previous research indicates that deshopping is a prevalent and growing consumer behaviour. This paper examines deshopping from a retail perspective. It is a case study of interviews conducted with a mass-market retailer, to investigate their awareness and management of this behaviour. Methodology: This paper is a case study of nine interviews conducted with different levels of staff at a mass-market retailer in their flagship London store, to investigate their awareness and management of deshopping. Findings: The findings demonstrate the beliefs, attitudes and emotions of the different levels of employees towards deshopping and demonstrates their attempts to manage deshopping and combat the negative affects of this on customer service. Research limitations: The limitation of this research is that it is only conducted with one high street retailer. However, it is important to highlight that this is a large womenswear retailer which is highly representative of other retailers within the sector. There is little detail given regarding the retailer itself or their fundamentals of the actual Customer Service Policy, this is due to the confidentiality agreement between the researcher and retailer. It is important to acknowledge the sensitivity of this type research to retailers who are reluctant to have this information publicised. It is also important to acknowledge that many retailers have not made any attempts to manage this behaviour by restricting their returns policy. So this research case study is conducted with a retailer that is actively introducing change to manage this behaviour. Practical implications: The research concludes with the implications of deshopping and its management and makes recommendations on how to reduce deshopping whilst maintaining customer service for the genuine consumer. Originality/value of the paper: This is the first case study with a mass market retailer highlighting their approaches towards managing deshopping whilst trying to maintain customer service

Improved molybdenum disulfide-silver motor brushes have extended life

Motor brushes of proper quantities of molybdenum disulfide and copper or silver are manufactured by sintering techniques. Graphite molds are used. These brushes operate satisfactorily for long periods in normal atmosphere or in a high-vacuum environment

Community acceptance of helicopter noise: Criteria and application

A study was conducted to define those criteria necessary for civil helicopter operations to be acoustically acceptable to the communities from which they operate and over which they fly. The study involved surveying existing domestic and foreign Federal regulations and guidelines, state and local noise ordinances, results of community noise annoyance studies, and results of individual aircraft noise annoyance studies, and results of individual aircraft noise annoyance studies in order to establish the criteria. The final criteria selection are based on the Day-Night Level, L sub DN, a measure of total noise exposure. The basic rating unit is the A weighted sound pressure level (dbA) which has accuracy comparable to other units currently used for aircraft. An L sub DN of 60 is recommended as a criterion for areas where the ambient noise is below 58 dbA. An L sub DN value 2 dbA above the local ambient is recommended for areas where the ambient is above 58 dbA