7,566 research outputs found

    Optimal control concepts in design sensitivity analysis

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    A close link is established between open loop optimal control theory and optimal design by noting certain similarities in the gradient calculations. The resulting benefits include a unified approach, together with physical insights in design sensitivity analysis, and an efficient approach for simultaneous optimal control and design. Both matrix displacement and matrix force methods are considered, and results are presented for dynamic systems, structures, and elasticity problems

    Near infra-red spectroscopy of V838 Monocerotis

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    Near IR, multi-epoch, spectroscopic and photometric observations of the enigmatic, eruptive variable V838 Mon in JHK bands are reported. One of the unusual features is the detection of several strong neutral TiI lines in emission in the K band. From the strength of these lines, the mass of the ejected envelope is estimated to be in the range 10e-7 to 10e-5 M(sun). The spectra also show the strong presence of the first and second overtones of 12CO bands seen in the K and H bands. The CO bands show a complex evolution. Deep water bands at 1.4 and 1.9 micron are also seen later in the object's evolution. Blackbody fits to the JHK photometric data show that V838 Mon has evolved to temperatures between 2400 - 2600 K by approximately 130 days after outburst. The spectra at this stage have the general characteristics of a very cool M giant.Comment: 7 pages, 5 figures, to appear in Astronomy and Astrophysic

    LAND TRANSFORMATION: A THREAT ON BANGALORE’S ECOLOGY - A CHALLENGE FOR SUSTAINABLE DEVELOPMENT

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    Land constitutes the most important character for sustainable development in a region. Rapid urbanization has become an area of crucial concern against the bonanza of urban ecology. The land use pattern of any urban area hints not only its immediate current space requirements of the inheriting community but rather the cumulative requirements over a period of year. Thus, the way a land use changes into, reveals a physical transformation of its economic use that indirectly unveils the demand for built-up space and as a result, the urban ecology is in imbroglio. For much of human existence, the available land for human use has appeared limitless. Wherever population densities have risen too high, there is a decline noticed in resource base. People moved on to occupy new lands by extending the urban area into rural fringe. Land transformation as the word suggests, traces the change of form in the land use. Land use change is an inevitable phenomenon in an urban space. How the use of land changed from one to another is a problem that has interconnections with various entities and the interaction between them in spatio-temporal environment. Bangalore over the years has grown as a robust technology hub, and has been ever- growing in terms of urban space with its inhabits. How this growth has affected its ecological space is the thrust of the study. The ecology of this urban land constitutes of agricultural plantation, forest area and lakes which comprise the green and blue spots. The objectives are accomplished through Geoinformatics which is able to apprehend statistics of ecological to the urban environment.Environmental Degradation, GIS, Remote Sensing, Digital Image Processing, Urban Land Transformation Analysis.

    Data Driven Computing by the Morphing Fast Fourier Transform Ensemble Kalman Filter in Epidemic Spread Simulations

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    The FFT EnKF data assimilation method is proposed and applied to a stochastic cell simulation of an epidemic, based on the S-I-R spread model. The FFT EnKF combines spatial statistics and ensemble filtering methodologies into a localized and computationally inexpensive version of EnKF with a very small ensemble, and it is further combined with the morphing EnKF to assimilate changes in the position of the epidemic.Comment: 11 pages, 3 figures. Submitted to ICCS 201

    Deformation mechanisms of NiAl cyclicly deformed near the brittle-to-ductile transformation temperature

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    One of the ongoing challenges of the aerospace industry is to develop more efficient turbine engines. Greater efficiency entails reduced specific strength and larger temperature gradients, the latter of which means higher operating temperatures and increased thermal conductivity. Continued development of nickel-based superalloys has provided steady increases in engine efficiency and the limits of superalloys have probably not been realized. However, other material systems are under intense investigation for possible use in high temperature engines. Ceramic, intermetallic, and various composite systems are being explored in an effort to exploit the much higher melting temperatures of these systems. NiAl is considered a potential alternative to conventional superalloys due to its excellent oxidation resistance, low density, and high melting temperature. The fact that NiAl is the most common coating for current superalloy turbine blades is a tribute to its oxidation resistance. Its density is one-third that of typical superalloys and in most temperature ranges its thermal conductivity is twice that of common superalloys. Despite these many advantages, NiAl requires more investigation before it is ready to be used in engines. Binary NiAl in general has poor high-temperature strength and low-temperature ductility. On-going research in alloy design continues to make improvements in the high-temperature strength of NiAl. The factors controlling low temperature ductility have been identified in the last few years. Small, but reproducible ductility can now be achieved at room temperature through careful control of chemical purity and processing. But the mechanisms controlling the transition from brittle to ductile behavior are not fully understood. Research in the area of fatigue deformation can aid the development of the NiAl system in two ways. Fatigue properties must be documented and optimized before NiAl can be applied to engineering systems. More importantly though, probing the deformation mechanisms operating in fatigue will lead to a better understanding of NiAl's unique characteristics. Low cycle fatigue properties have been reported on binary NiAl in the past year, yet those studies were limited to two temperature ranges: room temperature and near 1000 K. Eventually, fatigue property data will be needed for a wide range of temperatures and compositions. The intermediate temperature range near the brittle-to-ductile transition was chosen for this study to ascertain whether the sharp change occurring in monotonic behavior also occurs under cyclic conditions. An effort was made to characterize the dislocation structures which evolved during fatigue testing and comment on their role in the deformation process

    Factors Affecting the Adoption of Genetically Modified Crops by Young and Beginning U.S. Farmers and Ranchers

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    The comprehensive set of programs in the 2008 Farm Bill designed to support Young and Beginning Farmers and Ranchers (YBFR), combined with a substantial amount of resources allocated to each of these programs, can be viewed as an investment in ensuring the future sustainability of the U.S. agriculture system. Understanding the factors that influence YBFR to adopt technology will become increasingly important if YBFR are to succeed. Of particular interest is why YBFR adopt Bt corn, Bt cotton, and HT soybeans. Results conform to a majority of our a priori expectations; YBFRs are more likely to adopt GM crops if they are not a full owner of the farm operation, as sales of the farm operation grow, if the crop is important to their region, and as they become more risk averse.Agricultural and Food Policy,
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