Reactivity of N-alkylated cyclic imino ether salts having vinyl group

Summary Two copolymers of 2-isopropenyl-2-oxazolinium tetrafluoroborate with methyl methacrylate and with methyl acrylate were prepared, from which the polymerization of 2-oxazolines (2-methyl and 2-t-butyl) was initiated to prepare graft copolymers.     

Surface Energy Anisotropy of SrTiO3 at 1400°C in Air

Geometric and crystallographic measurements of grain-boundary thermal grooves and surface faceting behavior as a function of orientation have been used to determine the surface energy anisotropy of SrTiO₃ at 1400°C in air. Under these conditions, thermal grooves are formed by surface diffusion. The surface energy anisotropy was determined using the capillarity vector reconstruction method under the assumption that Herring's local equilibrium condition holds at the groove root. The results indicate that the (100) surface has the minimum energy. For surfaces inclined between 0° and 30° from (100), the energy increases with the inclination angle. Orientations inclined by more than 30° from (100) are all about 10% higher in energy and, within experimental uncertainty, energetically equivalent. A procedure for estimating the uncertainties in the reconstructed energies is also introduced. Taken together, the orientation dependence of the surface-facet formation and the measured energy anisotropy lead to the conclusion that the equilibrium crystal shape is dominated by {100}, but also includes {110} and {111} facets. Complex planes within about 15° of {100} and 5° of {110} are also part of the equilibrium shape.     

Ad-Molecule Orientation and Thermo- and Photo-Induced Surface-Aligned Desorption

Two-directional N₂ desorption was found in N₂O decomposition on Pd(110) at 100–160 K. It collimated ±43° off the surface normal in the (001) plane. A hot-atom-assisted model is proposed for N₂ desorption. Inclined O₂ desorption was simulated by hot atoms emitted from aligned oxygen molecules on stepped Pt(112) at 308 nm irradiation.     

Aluminum distribution in high-silica mordenite

The Al distribution in high-silica mordenite (MOR) zeolites with various Si/Al ratios was investigated by FT-IR spectroscopy in the presence of CD₃CN probe molecules and benzene adsorption. Two adsorption bands assigned to CN stretching vibration were observed at 2280–2295 and ≈2315 cm⁻¹, which are due to interaction of CN with acidic hydroxyl groups in the main channels and the side pockets of H-MOR zeolite, respectively. The relative intensity of the peak at 2315 cm⁻¹ increased with an increase in the Si/Al ratio, indicating that the proportion of Al atoms in the main channels relatively decreased with the Si/Al ratio. This was confirmed from the linear relationship between the number of benzene molecules adsorbed in a unit cell and the number of Al atoms in the main channels. In addition, this was also suggested from the computer simulation result that Al atoms are preferentially sitting in the T₃ site.     

Unsteady heat transfer from a circular cylinder immersed in a Darcy flow

Summary Analyses are made for unsteady heat transfer from a circular cylinder immersed in a porous medium through which a liquid is flowing according to Darcy's law. Asymptotic solutions for large and small Peclet numbers (Pe) are obtained for the case where the unsteady temperature field is produced by a step change in wall temperature. The former is valid for Pe200 and the latter for Pe0.1. The series solution for small time, which is valid for all values of Pe, is also obtained. By applying the Euler transformation to the series, its convergence is greatly improved, and it appears that the Eulerized series determines the mean Nusselt number adequately for most values of time.     

A cyber attack-resilient server inspired by biological diversity

This paper describes a novel cyber attack-resilient server inspired by the concept of biological diversity. The server consists of several virtual machines running different operating systems and different implementations of the same server protocol specification. This approach is based on the observation that not all implementations are affected by the same vulnerability, except for vulnerabilities in specifications and on shared libraries. A prototype system was built and tested to evaluate the continuity of the service. The results showed that, by exploiting a vulnerability, the prototype system could suppress downtime of the DNS service to less than 4 s without false positives.     

Identifying potential areas of Cannabis sativa plantations using object-based image analysis of SPOT-5 satellite data

The rapid and efficient detection of illicit drug cultivation, such as that of Cannabis sativa, is important in reducing consumption. The objective of this study was to identify potential sites of illicit C. sativa plantations located in the semi-arid, southern part of Pernambuco State, Brazil. The study was conducted using an object-based image analysis (OBIA) of Système Pour l'Observation de la Terre high-resolution geometric (SPOT-5 HRG) images (overpass: 31 May, 2007). OBIA considers the target's contextual and geometrical attributes to overcome the difficulties inherent in detecting illicit crops associated with the grower's strategies to conceal their fields and optimizes the spectral information extracted to generate land-cover maps. The capabilities of the SPOT-5 near-infrared and shortwave infrared bands to discriminate herbaceous vegetation with high water content, and employment of the support vector machine classifier, contributed to accomplishing this task. Image classification included multiresolution segmentation with an algorithm available in the eCognition Developer software package. In addition to a SPOT-5 HRG multispectral image with 10 m spatial resolution and a panchromatic image with 2.5 m spatial resolution, first-order indices such as the normalized difference vegetation index and ancillary data including land-cover classes, anthropogenic areas, slope, and distance to water sources were also employed in the OBIA. The classification of segments (objects) related to illegal cultivation employed fuzzy logic and fixed-threshold membership functions to describe the following spectral, geometrical, and contextual properties of targets: vegetation density, topography, neighbourhood, and presence of water supplies for irrigation. The results of OBIA were verified from a weight of evidence analysis. Among 15 previously known C. sativa sites identified during police operations conducted on 5–17 June 2007, eight sites were classified as maximum-alert areas (total area of 22.54 km² within a total area of object-oriented image classification of ～1800 km²). The approach proposed in this study is feasible for reducing the area to be searched for illicit cannabis cultivation in semi-arid regions.     

Biophysical characteristics and fire occurrence of cultivated pastures in the Brazilian savanna observed by moderate resolution satellite data

Cultivated pastures are the dominant land-use unit in Brazil, with the cattle raising sector representing ～50% of the total Brazilian emissions of greenhouse gases. About 44% of the Brazilian cattle herd is located in the 204 million ha Cerrado, the Brazilian savanna biome and one of the world's hotspots for conservation, where pasture is still the major driving force behind the ongoing land clearance. In the face of the environmental challenges posed by the Cerrado cultivated pastures, 50% of which are estimated to be already severely degraded and where most of the pasture-related fires in Brazil occur, in this study we report the findings on the use of key Moderate Resolution Imaging Spectroradiometer (MODIS) Land (MODLAND) products for retrieving biophysical patterns and trends of cultivated pastures over the entire Brazilian savanna biome. The areas of Cerrado covered by cultivated pastures were analysed by the following 2008 MODIS products: MOD13Q1 enhanced vegetation index, MOD11A2 land-surface temperature, MOD15A2 leaf area index, and MCD45A1 fire-affected areas. Specifically, 23 MOD13Q1 composites for the whole year of 2008 were used as a net primary productivity proxy. Our results indicate the ability of moderate resolution orbital imagery to consistently depict the main characteristics and regional variation in the biophysical properties of the Cerrado pastures, which clearly depend on management practices, usage, and environmental conditions. In particular, these results corroborate the feasibility of an operational MODIS-based monitoring system providing early fire warnings and overall quality assessments in support of a more efficient and sustainable herd occupation and more appropriate land-use destination.     

Spatial and temporal probabilities of obtaining cloud‐free Landsat images over the Brazilian tropical savanna

Remotely sensed data are the best and perhaps the only possible way for monitoring large‐scale, human‐induced land occupation and biosphere‐atmosphere processes in regions such as the Brazilian tropical savanna (Cerrado). Landsat imagery has been intensively employed for these studies because of their long‐term data coverage (>30 years), suitable spatial and temporal resolutions, and ability to discriminate different land‐use and land‐cover classes. However, cloud cover is the most obvious constraint for obtaining optical remote sensing data in tropical regions, and cloud cover analysis of remotely sensed data is a requisite step needed for any optical remote sensing studies. This study addresses the extent to which cloudiness can restrict the monitoring of the Brazilian Cerrado from Landsat‐like sensors. Percent cloud cover from more than 35 500 Landsat quick‐looks were estimated by the K‐means unsupervised classification technique. The data were examined by month, season, and El Niño Southern Oscillation event. Monthly observations of any part of the biome are highly unlikely during the wet season (October–March), but very possible during the dry season, especially in July and August. Research involving seasonality is feasible in some parts of the Cerrado at the temporal satellite sampling frequency of Landsat sensors. There are several limitations at the northern limit of the Cerrado, especially in the transitional area with the Amazon. During the 1997 El Niño event, the cloudiness over the Cerrado decreased to a measurable but small degree (5% less, on average). These results set the framework and limitations of future studies of land use/land cover and ecological dynamics using Landsat‐like satellite sensors.     

Identification of Hammerstein systems without explicit parameterisation of non-linearity

This article proposes a new approach to identification of Hammerstein systems, where a non-linearity precedes a linear dynamic system, driven by piece-wise constant inputs. The proposed approach does not require an explicit parameterisation of the non-linearity. Moreover, the non-linearity does not have to be static, but could be the one with finite memories like backlash. By exploiting input's piecewise constant property, the denominator of the linear system described by an ARX model is consistently identified from the information of the output only; next, a subspace direct equalisation method estimates the unmeasurable inner signal based on the resulted denominator estimate and output measurements. Contrary to the existing blind approaches, the numerator of the linear system is not required, which leads to a significant improvement of removing an error propagation. On the basis of the estimated inner signal, the measured input and output, the non-linearity and linear system are obtained separately. The proposed approach is validated and compared with two existing blind approaches through numerical and experimental examples.