5,404 research outputs found
A novel design concept for space-based polar remote sensing
Space-based remote sensing of the Earth is conducted from a fleet of spacecraft in two basic orbital positions, near-polar low-Earth orbits and geosynchronous orbits, with each offering its own advantages and disadvantages. Low-Earth orbits provide high-resolution observations at the expense of large-scale contextual information, while geosynchronous orbits provide near-global, continuous coverage at reduced resolutions. However, due to the rapidly decreasing horizontal resolution data-products derived from geosynchronous orbits are of degraded value beyond approximately 55 degrees of latitude. A novel mission design is introduced to enable continuous observation of all longitudes at latitudes between 55 and 90 degrees with an observation zenith angle of less than 60 degrees, without the use of composite images. A single Soyuz launch is used to deliver three spacecraft to 12-hr, highly eccentric true-polar orbits with apogee at 40170 km and electric propulsion is used to maintain the orbit apse-line coincident with the Earth’s poles. It is shown that the science payload mass can be traded against the mission duration, with a payload mass varying between 120 – 90 kg for mission durations between 3 – 5 years, respectively. It is further shown that the payload would have approximately of 2kW of power available during operations as the electric propulsion system is not operated at these times. Whilst the payload mass is less than a typical remote sensing platform in geosynchronous orbit it is considered that the concept would offer an excellent technology demonstrator mission for operational missions, whilst also enabling unique and valuable science
A hybrid perturbation-Galerkin technique for partial differential equations
A two-step hybrid perturbation-Galerkin technique for improving the usefulness of perturbation solutions to partial differential equations which contain a parameter is presented and discussed. In the first step of the method, the leading terms in the asymptotic expansion(s) of the solution about one or more values of the perturbation parameter are obtained using standard perturbation methods. In the second step, the perturbation functions obtained in the first step are used as trial functions in a Bubnov-Galerkin approximation. This semi-analytical, semi-numerical hybrid technique appears to overcome some of the drawbacks of the perturbation and Galerkin methods when they are applied by themselves, while combining some of the good features of each. The technique is illustrated first by a simple example. It is then applied to the problem of determining the flow of a slightly compressible fluid past a circular cylinder and to the problem of determining the shape of a free surface due to a sink above the surface. Solutions obtained by the hybrid method are compared with other approximate solutions, and its possible application to certain problems associated with domain decomposition is discussed
Mirror reflectometer based on optical cavity decay time
Described is a reflectometer capable of making reflectivity measurements of low-loss highly reflecting mirror coatings and transmission measurements of low-loss antireflection coatings. The technique directly measures the intensity decay time of an optical cavity comprised of low-loss elements. We develop the theoretical framework for the device and discuss in what conditions and to what extent the decay time represents a true measure of mirror reflectivity. Current apparatus provides a decay time resolution of 10 nsec and has demonstrated a cavity total loss resolution of 5 ppm
POTENTIAL EFFECTS OF SUBSIDIZED LIVESTOCK INSURANCE ON LIVESTOCK PRODUCTION
Recent legislation has cleared the way for subsidized livestock price insurance. Such programs could increase production. Expected feeder cattle prices with and without subsidized insurance will be analyzed using E-V and Stochastic Dominance. Results will highlight the potential effects of the program on marketing risk and production decisions.Livestock Production/Industries, Risk and Uncertainty,
Grain Drying With Supplemental Solar Heat
The use of solar energy for drying shelled corn was investigated. In a three-year field study, energy re-quirements of a conventional low-temperature electric drying installation were compared with those of a similar system supplemented with the output of a simple, inex-pensive solar collector
Shrinkage and Corn Quality Changes in On-Farm Handling Operations
Material handling losses and corn quality changes were measured in three typical on-farm corn-drying systems. Handling losses averaged 0.78% of initial weight, with a range of 0.40% to 1.71% of initial weight. There was no indication that handling losses were related to initial moisture content. Handling losses were less than would have been assessed in shrink had the corn been delivered wet to a grain buyer. Test weight increased during drying, but the simplified Hall and Hill test weight adjustment table overpredicted these increases
Recommended from our members
Targeting the UPS as Therapy in Multiple Myeloma
The coordinated regulation of cellular protein synthesis and degradation is essential for normal cellular functioning. The ubiquitin proteasome system mediates the intracellular protein degradation that is required for normal cellular homeostasis. The 26S proteasome is a multi-enzyme protease that degrades redundant proteins; conversely, inhibition of proteasomal degradation results in intracellular aggregation of unwanted proteins and cell death. This observation led to the development of proteasome inhibitors as therapeutics for use in cancer. The clinical applicability of targeting proteasomes is exemplified by the recent FDA approval of the first proteasome inhibitor, bortezomib, for the treatment of relapsed/refractory multiple myeloma. Although bortezomib represents a major advance in the treatment of this disease, it can be associated with toxicity and the development of drug resistance. Importantly, extensive preclinical studies suggest that combination therapies can both circumvent drug resistance and reduce toxicity. In addition, promising novel proteasome inhibitors, which are distinct from bortezomib, and exhibit equipotent anti-multiple myeloma activities, are undergoing clinical evaluation in order to improve patient outcome in multiple myeloma. Republished from Current BioData's Targeted Proteins database (TPdb;
http://www.targetedproteinsdb.com)
- …
