SMOS REFLEX 2003: L-band emissivity characterization of vineyards

The goal of the Soil Moisture and Ocean Salinity mission over land is to infer surface soil moisture from multiangular L-band radiometric measurements. As the canopy affects the microwave emission of land, it is necessary to characterize different vegetation layers. This paper presents the Reference Pixel L-Band Experiment (REFLEX), carried out in June-July 2003 at the Vale/spl grave/ncia Anchor Station, Spain, to study the effects of grapevines on the soil emission and on the soil moisture retrieval. A wide range of soil moisture (SM), from saturated to completely dry soil, was measured with the Universitat Polite/spl grave/cnica de Catalunya's L-band Automatic Radiometer (LAURA). Concurrently with the radiometric measurements, the gravimetric soil moisture, temperature, and roughness were measured, and the vines were fully characterized. The opacity and albedo of the vineyard have been estimated and found to be independent on the polarization. The /spl tau/--/spl omega/ model has been used to retrieve the SM and the vegetation parameters, obtaining a good accuracy for incidence angles up to 55/spl deg/. Algorithms with a three-parameter optimization (SM, albedo albedo, and opacity) exhibit a better performance than those with one-parameter optimization (SM).     

Formation of Al2O3/Metal Composites by the Directed Oxidation of Molten Aluminum-Magnesium-Silicon Alloys: Part I, Microstructural Development

The growth of α-Al₂O₃/metal composites by the directed oxidation of molten Al-Mg-Si alloys proceeds through four distinct stages. The first stage encompasses the early heating of the alloy ingot, melting, and continued heating to between 1123 and 1173 K. In this latter temperature range, the molten alloy surface rapidly oxidizes to form a MgO-covered MgAl₂O₄ layer. During further heating and initial soak at the composite growth temperature (1373 to 1573 K), the duplex layer slowly thickens (second stage). The start of the third stage, growth initiation, is marked by the spread of a metal-rich zone over the duplex layer; this metal-rich zone is believed to be connected to the molten alloy through microcracks in the thickened MgO/MgAl₂O₄ layer. Small nodules of the oxide/metal composite nucleate from the metal-rich layer. During the final rapid growth stage, the small composite nodules grow and coalesce to form a macroscopically planar growth front, which persists until growth is complete. Throughout the growth process, the external surface of the α-Al₂O₃/metal composite is covered by a thin MgO layer. Immediately under this external layer and separating it from the α-Al₂O₃ is a thin layer of molten metal.     

用SpartanTM-Ⅱ FPGA实现Reed-Solomon编码/译码方案

本文简述Reed-Solomon纠错理论及用Xilinx Spartan TM-Ⅱ系列FPGA实现Reed-Solomon编码/译码方案.     

Evolutionary relationships among the Braconidae (Hymenoptera: Ichneumonoidea) inferred from partial 16S rDNA gene sequences

Phylogenetic relationships among the Braconidae were examined using homologous 16S rDNA gene sequence data. Analyses recovered the few well-supported relationships evident in this family from morphological analyses, viz the monophyly of the microgastroid complex of subfamilies, the monophyly of the cyclostome complex of subfamilies (= braconoids), a sister-group relationship between the Alysiinae and Opiinae, and a close relationship between the Helconinae and Blacinae. With respect to the braconoid complex of subfamilies, a sister-group relationship was recovered between Aphidiinae and Mesostoinae, and a clade composed of Gnamptodontinae + Histeromerinae + Rhyssalinae + Aphidiinae + Mesostoinae was also recovered. The Doryctinae and Rogadinae sensu lato (s.l.) were generally not resolved as monophyletic. With respect to the helconoid complex of subfamilies, a sister-group relationship was recovered between Sigalphinae and Agathidinae, whereas Neoneurinae fell out among other helconoid subfamilies. Other relationships among the helconoid subfamilies were unclear from these analyses. With respect to the microgastroid complex of subfamilies, our data conform to morphological estimates, recovering ((Microgastrinae + Miracinae) + Cardiochilinae) + Cheloninae. The topology of our trees suggests that the cyclostome subfamilies are a natural derived group, inferring that endoparasitism (not ectoparasitism) is the ancestral state for the Braconidae, unless all of the ectoparasitic ancestors of the helconoid + microgastroid subfamilies are now extinct.     

A study of the reaction of CO on liquid iron alloys

In all previous studies of the CO reaction on liquid iron the rate was controlled by liquid phase mass transfer. In this study an isotope exchange technique was used to eliminate liquid phase mass transfer as a possible rate-controlling mechanism. The rate in the present work is over an order of magnitude faster than previously measured. The isotope exchange rate for C¹³O¹⁸ in normal CO on liquid iron was not a function of temperature or sulfur content up to 0.43 pct S, but was a function of gas flow rate, indicating that the rate is controlled by gas phase mass transfer. the mass transfer parameter for the specific experimental condition was determined and the calculated rate for gas phase mass transfer of C¹³O¹⁸ in CO controlling the rate is in agreement with the experimental results. At low temperatures (1523 K) and sulfur contents greater than 0.015 pct the rate may be controlled by mixed control, gas phase mass transfer, and chemical kinetics in series. The chemical rate constant is estimated to be 1.5×10⁻⁵ moles/cm² sec atm for these conditions. S. ANTOLIN, formerly Granduate Student at Carnegie Mellon University     

用Spartan^TM—II FPGA实现Reed—Solomon编码／译码方案

本文简述Ｒｅｅｄ－Ｓｏｌｏｍｏｎ纠错理论及用Ｘｉｌｉｎｘ－Ｓｐａｒｔａｎ＾ＴＭ－ＩＩ系列ＦＰＧＡ实现Ｒｅｅｄ－Ｓｏｌｏｍｏｎ编码／译码方案。     

Structure of Aluminum Nitride/Aluminum and Aluminum Oxide/Aluminum Composites Produced by the Directed Oxidation of Aluminum

Unreinforced AlN/Al ceramic/metal composites were produced by the directed oxidation of molten Al alloys in nitrogen. The microstructures of these composites were compared with those of previously studied Al₂O₃/Al composites. In both composite systems the ceramic phase was interconnected and oriented in a columnar structure. The metallic phase showed no significant crystallographic orientation and appeared as both interconnected channels and isolated inclusions. The columns in the nitride system were found to be of micrometer size and to contain subgrains weakly defined by lattice defects, unlike the oxide system, where the columnar structure was shown to be of millimeter size and to contain well-defined micrometer-sized subgrains. Finer structures were obtained in both systems via the addition of Ni to the parent alloy.     

Analysis of the sensitivity properties of a model of vector-borne bubonic plague.

Model sensitivity is a key to evaluation of mathematical models in ecology and evolution, especially in complex models with numerous parameters. In this paper, we use some recently developed methods for sensitivity analysis to study the parameter sensitivity of a model of vector-borne bubonic plague in a rodent population proposed by Keeling & Gilligan. The new sensitivity tools are based on a variational analysis involving the adjoint equation. The new approach provides a relatively inexpensive way to obtain derivative information about model output with respect to parameters. We use this approach to determine the sensitivity of a quantity of interest (the force of infection from rats and their fleas to humans) to various model parameters, determine a region over which linearization at a specific parameter reference point is valid, develop a global picture of the output surface, and search for maxima and minima in a given region in the parameter space.