Variations of chlorophyll-a in the northeastern Indian Ocean after the 2004 South Asian tsunami

Analysis of satellite remote sensing data has revealed changes in distribution of chlorophyll-a (Chl-a) and sea surface temperature (SST) in the Indian Ocean during the South Asian tsunami in December 2004. Chl-a data derived from Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) images were examined for the period from 1998 to 2005. Around the epicentre of the Sumatra earthquake, the Chl-a concentration was found to increase prior to the main event on 26 December 2004 and then decrease during the tsunami event, while a high SST (～30–31°C) was observed in and around the epicentral region. Chl-a concentrations in the coastal waters of the Southeast Asian countries were remarkably low during and after the tsunami. Similar but relatively small variations in Chl-a and SST were observed during the second earthquake on 28 March 2005. Analysis of Chl-a, SST, wind and upwelling water has provided information for understanding the changes in Chl-a concentration during the tsunami. A very large offshore phytoplankton bloom (～300 km²) appeared to the southeast of Sri Lanka about 3 weeks after the tsunami; this might have been caused by a tropical storm that could be responsible for the enhancement of nutrients.     

Gram yield estimation through SVI under variable soil and management conditions

Soil crop management interaction influence on spectral vegetation indices (SVIs) and dry matter (DM) in different growth stages of gram crop were studied through an experiment. Significant differences in the values of IR/R and NDVI in the branching stage (St1: 20.17***, 14.06***) and the pod development stage (St2: 12.73***, 8.48**) and non-significant differences in pod maturity stage (St3: 0.193, 0.023) indicate that plant, soil and management interactions have yielded significant difference up to St2. The values of coefficient of variation (Cv) show the significant differences in DM production between the soils (St1: 43.5***, St2: 228.5***, St3: 36.3***) and treatment (St1: 10.8***, St2: 6.6**, St3: 2.9). These variation are well in agreement with the changes which have taken place in the values of SVIs, as it can be clearly seen that the increase in SVIs corresponds with the consistent increase in DM up to stage 2. The significant differences between SVIs values between soils and treatments and the positive correlation with DM at St2, justifies their consideration in estimating the yield of gram crop under variable soil and management conditions. The regression relation of DM with NDVI in three soils and four management factors has yielded 12 regression models in order to predict DM/grain production using SVI's values in St2. Based on goodness of fit and considering the highest R2 value, the best yield prediction models for S1, S2 and S3 soils are (i) y 0.91 0.03 NDVI (R2 0.42) S1 soils (ii) y 1.89 0.06 NDVI (R2 0.96) S2 soils (iii) y 3.85 0.46 NDVI (R2 0.32) S3 soils.     

H∞ control of switched delayed systems with average dwell time

This paper considers the problems of stability analysis and H_∞ controller design of time-delay switched systems with average dwell time. In order to obtain less conservative results than what is seen in the literature, a tighter bound for the state delay term is estimated. Based on the scaled small gain theorem and the model transformation method, an improved exponential stability criterion for time-delay switched systems with average dwell time is formulated in the form of convex matrix inequalities. The aim of the proposed approach is to reduce the minimal average dwell time of the systems, which is made possible by a new Lyapunov–Krasovskii functional combined with the scaled small gain theorem. It is shown that this approach is able to tolerate a smaller dwell time or a larger admissible delay bound for the given conditions than most of the approaches seen in the literature. Moreover, the exponential H_∞ controller can be constructed by solving a set of conditions, which is developed on the basis of the exponential stability criterion. Simulation examples illustrate the effectiveness of the proposed method.     

Some results on Parametric Temporal Logic

Parametric Temporal Logic extends linear temporal logic by allowing the temporal operators to additionally specify quantitative and parametric bounds on event occurrences. In this paper, we revisit and provide improved solutions to the four important problems of emptiness, universality, finiteness and construction considered in the literature for this logic.     

Simulation of unsteady two-phase flows using a parallel Eulerian–Lagrangian approach

The present study details the implementation of a time accurate method for the tracking of particles being acted upon by a continuous gas phase and gravity. The Lagrangian particle tracking approach was implemented within the framework of a parallel, incompressible, unstructured, node-centered finite-volume flow solver. The paper gives a method for selecting time steps for individual particles such that interactions with the continuum phase are updated at particle locations nearest the continuum-phase nodes while constraining the particle from passing beyond boundaries of the relevant adjacent cell. An implementation of this technique for three-dimensional nonuniform multi-element unstructured grids is given in the context of domain decomposition for implementation on distributed-memory parallel computers. Results of simulations with and without particle–particle collisions compare favorably with experimental validation results.     

Online keyword based advertising: Impact of ad impressions on own-channel and cross-channel click-through rates

Keyword-based ads are becoming the dominant form of advertising online as they enable customization and tailoring of messages relevant to potential consumers. Two prominent channels within this sphere are the search channel and the content channel. We empirically examine the interaction between these two channels. Our results indicate significant cannibalization across the two channels as well as significant diminishing returns to impressions within each channel. This suggests that under certain conditions both channels may need to be used to optimize returns to advertising both for advertisers and service providers such as Google. Our game theoretic analysis which builds upon our empirical findings reveals that for intermediate budget values it is optimal to use both channels whereas for very low (very high) budget values it is optimal to use only the content (search) channel. Further as budget increases the advertiser should offer more for ads displayed on the search channel to optimally incentivize the service provider.     

Looking Around the Corner using Ultrafast Transient Imaging

We propose a novel framework called transient imaging for image formation and scene understanding through impulse illumination and time images. Using time-of-flight cameras and multi-path analysis of global light transport, we pioneer new algorithms and systems for scene understanding through time images. We demonstrate that our proposed transient imaging framework allows us to accomplish tasks that are well beyond the reach of existing imaging technology. For example, one can infer the geometry of not only the visible but also the hidden parts of a scene, enabling us to look around corners. Traditional cameras estimate intensity per pixel I(x,y). Our transient imaging camera captures a 3D time-image I(x,y,t) for each pixel and uses an ultra-short pulse laser for illumination. Emerging technologies are supporting cameras with a temporal-profile per pixel at picosecond resolution, allowing us to capture an ultra-high speed time-image. This time-image contains the time profile of irradiance incident at a sensor pixel. We experimentally corroborated our theory with free space hardware experiments using a femtosecond laser and a picosecond accurate sensing device. The ability to infer the structure of hidden scene elements, unobservable by both the camera and illumination source, will create a range of new computer vision opportunities.     

Pure and Pt-loaded gamma iron oxide as sensor for detection of sub ppm level of acetone

In this study, pure and Pt-loaded nanocrystalline γ-Fe₂O₃ have been prepared by precipitation using ultrasonic irradiation. The synthesized powders were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), transmission electron micrograph (TEM), selected area electron diffraction (SAED), scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Pure nanocrystallline γ-Fe₂O₃ sensors were found to show good response towards sub ppm level of acetone at 250 °C, and improves significantly on Pt loading. As an example, 1 wt% Pt loading of nanocrystallline γ-Fe₂O₃ increased its response towards acetone by 55%. The high response of γ-Fe₂O₃ holds it as a potentially promising candidate for acetone detection which may lead for the non-invasive testing of diabetics.     

Host emission from BaMgAl10O17 and SrMgAl10O17 phosphor: Effects of temperature and defect level

Abstract— Understanding the mechanism of blue‐light emission in Eu‐doped BAM phosphor as well as its sensitive degradation is required because this is a very important material in fluorescent lamps and plasma‐display panels. In this study, both theoretical and experimental investigations on the host emissions in BaMgAl¹⁰O¹⁷ and SrMgAl¹⁰O¹⁷ were performed. Host emissions from BaMgAl¹⁰O¹⁷ and SrMgAl¹⁰O¹⁷ by photoluminescence and thermoluminescence spectra were observed. Photoluminescence spectra suggested that the host emission from SrMgAl¹⁰O¹⁷ was easily quenched by thermal vibrations. The thermoluminescence spectra showed the existence of shallow and deep defect levels in BaMgAl¹⁰O¹⁷ and SrMgAl¹⁰O¹⁷ phosphors. It was shown that SrMgAl¹⁰O¹⁷ and its conduction plane could undergo degradation during irradiation of vacuum‐ultra‐violet (VUV) lights based on the calculated energy of formation of an oxygen vacancy. Moreover, the structural defects, such as oxygen vacancies, would cause localizing levels in the upper level in the valence band and in theconduction band. The results suggest the contribution of the host emission to the energy transfer to the Eu atoms would not be significant and the oxygen vacancies would act as the traps for excited carriers.     

Modeling climate change uncertainties in water resources management models

The impact of climate change on hydrologic design and management of hydrosystems could be one of the important challenges faced by future practicing hydrologists and water resources managers. Many water resources managers currently rely on the historical hydrological data and adaptive real-time operations without consideration of the impact of climate change on major inputs influencing the behavior of hydrologic systems and the operating rules. Issues such as risk, reliability and robustness of water resources systems under different climate change scenarios were addressed in the past. However, water resources management with the decision maker’s preferences attached to climate change has never been dealt with. This short paper discusses issues related to impacts of climate change on water resources management and application of a soft-computing approach, fuzzy set theory, for climate-sensitive management of hydrosystems. A real-life case study example is presented to illustrate the applicability of a soft-computing approach for handling the decision maker’s preferences in accepting or rejecting the magnitude and direction of climate change.