12,592 research outputs found
Design of a 12 channel fm microwave receiver
The design, fabrication, and performance of elements of a low cost FM microwave satellite ground station receiver is described. It is capable of accepting 12 contiguous color television equivalent bandwidth channels in the 11.72 to 12.2 GHz band. Each channel is 40 MHz wide and incorporates a 4 MHz guard band. The modulation format is wideband FM and the channels are frequency division multiplexed. Twelve independent CATV compatible baseband outputs are provided. The overall system specifications are first discussed, then consideration is given to the receiver subsystems and the signal branching network
Program on application of communications satellites to educational development: Design of a 12 channel FM microwave receiver
The design, fabrication, and performance of elements of a low cost FM microwave satellite ground station receiver is described. It is capable of accepting 12 contiguous color television equivalent bandwidth channels in the 11.72 to 12.2 GHz band. Each channel is 40 MHz wide and incorporates a 4 MHz guard band. The modulation format is wideband FM and the channels are frequency division multiplexed. Twelve independent CATV compatible baseband outputs are provided. The overall system specifications are first discussed, then consideration is given to the receiver subsystems and the signal branching network
Greene Gardens
The case describes the 2006 E. coli outbreak in the California spinach industry. The case unfolds over a period of about one month, with four separate eventful days described in detail. At the end of the narrative for each day, the reader is asked to decide how he or she would respond to the events and justify his or her decision.business ethics, communication, crisis management, spinach, Food Consumption/Nutrition/Food Safety, Health Economics and Policy, Teaching/Communication/Extension/Profession, Q10, Q13,
An analysis of the effect of aeroassist maneuvers on orbital transfer vehicle performance
This paper summarizes a Langley Research Summer Scholars (LARSS) research project (Summer 1986) dealing with the topic of the effectiveness of aeroassist maneuvers to accomplish a change in the orbital inclination of an Orbital Transfer Vehicle (OTV). This task was subject to OTV design constraints, chief of which were the axial acceleration and the aerodynamic heating rate limits of the OTV. The use of vehicle thrust to replace lost kinetic energy and, thereby, to increase the maximum possible change in orbital inclination was investigated. A relation between time in the hover orbit and payload to LEO was established. The amount of plane change possible during this type of maneuver was checked for several runs and a possible thrusting procedure to increase the plane change and still get to LEO was suggested. Finally, the sensitivity of various target parameters to controllable independent variables was established, trades between the amount of control allowed, and payload to LEO suggested
The Long-term Coercive Effect of State Community Benefit Laws on Hospital Community Health Orientation
This study is an examination of the long-term coercive effect of state community benefit laws (CB Laws) on the provision of community health activities in U.S. acute care hospitals. The sample included all the not-for-profit and investor owned acute care hospitals for which 1994 and 2006 AHA Annual Survey data were available. A panel design was used to longitudinally examine the effect that state CB Laws had on hospital community health orientation activities and the provision of health promotion services, after controlling for the influence of other organizational and environmental variables that might affect these activities and services. The authors found that both CB Law state and non CB Law state hospitals increased their number of orientation activities and promotion services from 1994 to 2006. However, there was no significant difference in the gains in these activities and services between these two groups of hospitals. These results suggest that other environmental and organizational factors may mediate the effect of the state CB Laws over time
Resource-Constrained Adaptive Search and Tracking for Sparse Dynamic Targets
This paper considers the problem of resource-constrained and noise-limited
localization and estimation of dynamic targets that are sparsely distributed
over a large area. We generalize an existing framework [Bashan et al, 2008] for
adaptive allocation of sensing resources to the dynamic case, accounting for
time-varying target behavior such as transitions to neighboring cells and
varying amplitudes over a potentially long time horizon. The proposed adaptive
sensing policy is driven by minimization of a modified version of the
previously introduced ARAP objective function, which is a surrogate function
for mean squared error within locations containing targets. We provide
theoretical upper bounds on the performance of adaptive sensing policies by
analyzing solutions with oracle knowledge of target locations, gaining insight
into the effect of target motion and amplitude variation as well as sparsity.
Exact minimization of the multi-stage objective function is infeasible, but
myopic optimization yields a closed-form solution. We propose a simple
non-myopic extension, the Dynamic Adaptive Resource Allocation Policy (D-ARAP),
that allocates a fraction of resources for exploring all locations rather than
solely exploiting the current belief state. Our numerical studies indicate that
D-ARAP has the following advantages: (a) it is more robust than the myopic
policy to noise, missing data, and model mismatch; (b) it performs comparably
to well-known approximate dynamic programming solutions but at significantly
lower computational complexity; and (c) it improves greatly upon non-adaptive
uniform resource allocation in terms of estimation error and probability of
detection.Comment: 49 pages, 1 table, 11 figure
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