Automated extraction and classification of thunderstorm and non-thunderstorm wind data for extreme-value analysis

Design wind loads are partly based on extreme value analyses of historical wind data, and limitations on the quantity and spatial resolution of wind data pose a significant challenge in such analyses. A promising source of recent wind speed and direction data is the automated surface observing system (ASOS), a network of about 1000 standardized US weather stations. To facilitate the use of ASOS data for structural engineering purposes, procedures and software are presented for (a) extraction of peak gust wind data and thunderstorm observations from archived ASOS reports, (b) classification of wind data as thunderstorm or non-thunderstorm to enable separate analyses, and (c) construction of data sets separated by specified minimum time intervals to ensure statistical independence. The procedures are illustrated using approximately 20-year datasets from three ASOS stations near New York City. It is shown that for these stations thunderstorm wind speeds dominate the extreme wind climate at long return periods. Also presented are estimates based on commingled data sets (i.e., sets containing, indiscriminately, both non-thunderstorm and thunderstorm wind speeds), which until now have been used almost exclusively for extreme wind speed estimates in the US. Analyses at additional stations will be needed to check whether these results are typical for locations with both thunderstorm and non-thunderstorm winds.     

Synthesis and characterization of citric acid-based pH-sensitive biopolymeric hydrogels

Biocompatible hydrogels based on citric acid (CA) with varying glycol unit, viz., ethylene glycol (EG), diethylene glycol and triethylene glycol were prepared along with acrylic acid. The formations of various hydrogels were confirmed using spectral techniques such as FT-IR and ¹H NMR. Thermal stability (thermogravimetric analysis, DTA and differential scanning calorimetry) and morphology (SEM) of the synthesized hydrogels were investigated. Swelling studies of hydrogels at various pH values ranging from 4.0 to 10.0 were also investigated. The results of swelling studies show that the percentage of swelling is comparatively higher at higher pH than lower pH. Swelling equilibrium for various hydrogels was also found. Increased composition of CA in hydrogels at different pH values of 4.0, 6.0, 7.4, 8.0 and 10.0 enhanced the swelling equilibrium.     

Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model

Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana, these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity.     

Partial coalescence as a tool to control sensory perception of emulsions

This study evaluates the role of partial coalescence of whey protein-stabilized emulsions on sensory perception. The selection of fats was restricted to vegetable fats that are essentially melted at oral temperatures. The sensitivity to partial coalescence was controlled by a variation in the fat melting curve and by addition of unsaturated monoglyceride. Most fat-related sensory attributes appear to be well-correlated to an increase in viscosity and coalescence in the mouth due to partial coalescence. Moreover, it was found that in-mouth aeration induces extra coalescence, which increases the perception of fat-related sensory attributes significantly.     

Classification of soil‐ and bedrock‐dominated landslides in British Columbia using segmentation of satellite imagery and DEM data

Landsat Enhanced Thematic Mapper Plus (ETM+) and digital elevation model (DEM) data were used in a segmentation and classification procedure to classify slide scars in the northern Cascade Mountains of British Columbia, Canada. The area was stratified into features that were likely candidates for landsliding and those that were not; shape criteria were applied that were used to identify objects as slides; and finally, rules based on shape, texture and neighbouring features were used to separate soil‐dominated slides from bedrock‐dominated slides, an important distinction in mass movement inventories and for applied and theoretical studies. Approximately 65% classification accuracy was obtained. Slopes experiencing multiple failures, which can create less distinct features on the ground, may have contributed to some of the error in classification.     

Energy-efficient directional routing between partitioned actors in wireless sensor and actor networks

Actor?actor communication is an important part of the functioning of wireless sensor?actor networks and enables the actor nodes to take coordinated action on a given event. Owing to various reasons such as actor mobility and low actor density, the actor network tends to get partitioned. The authors propose to use the underlying sensor nodes, which are more densely deployed, to heal these partitions. In order to maximise the utilisation of the limited energy available with the sensor nodes, a new routing protocol for actor?actor communication using directional antennas on the actor nodes is proposed. The authors contribution is threefold. First, using simulations they show that the problem of partitioning in the actor networks is significant and propose an architecture with directional antennas on actor nodes and sensor bridges to heal these partitions. Second, they identify the routing problem for this architecture based on a theoretical framework and propose centralised as well as distributed solutions to it. Third, they develop a routing protocol based on the distributed solution and show, using network simulations, that the proposed protocol not only heals the network partitions successfully, but also achieves high throughput and fairness across different flows, in addition to maximising the network lifetime.