A survey of sensory data boundary estimation,covering and tracking techniques using collaborating sensors

Boundary estimation and tracking have important applications in the areas of environmental monitoring and disaster management. A boundary separates two regions of interest in a phenomenon. It can be visualized as an edge if there is a sharp change in the field value between the two regions or alternatively, as a contour with a field value $f=\tau$ separating two regions with field values $f>\tau$ and $f<\tau$. Examples include contours/boundaries of hazardous concentration in a pollutant spill, frontal boundary of a forest fire, isotherms, isohalines etc. Recent advances in the area of embedded sensor devices and robotics have led to deployments of networks of sensors capable of sensing, computing, communication and mobility. They are used to estimate the boundaries of interest in physical phenomena, monitor or track them over time and also in some cases, mitigate the spatial spread of the phenomena. Since these sensors work autonomously in the environment, minimizing the energy consumed while maximizing the accuracy of estimation or tracking is the main challenge for algorithms for boundary estimation and tracking. Several algorithms with these objectives have been proposed in the literature. In this work, we focus on the algorithms that estimate and cover boundaries found in the sensory data in a field and not the topological boundary of the sensor network per se, which is beyond the scope of this paper.Here, our objective is to provide a comprehensive survey of the algorithms for boundary estimation and tracking by providing a taxonomy based on two broad categories — (i) Boundary estimation and tracking, where the sensors estimate the boundary without physically covering the boundary and (ii) Boundary covering — where the sensors not only predict the location and estimate the entire boundary but also physically cover the boundary by surrounding and bounding it. We further classify the techniques based on (a) sensing capabilities —in situ, range or remote sensing (b) movement capabilities — static or mobile sensors and (c) boundary type — static or dynamic and (d) type of estimation — field estimation where the entire field is sampled to search for contours and localized estimation where sampling is done near the boundary and (e) different types of mobility models in the case of mobile sensors. We believe that such a survey has not been performed before. By capturing and classifying the current state-of-the-art and identifying open research problems, we hope to ignite interest and stimulate efforts towards promising solutions for real-world boundary estimation and tracking problems.     

Scientific basis for establishing country greenhouse gas estimates for rice-based agriculture: An Indian case study

A comprehensive scientific assessment of CH₄ budget estimation for Indian rice paddies, based on a decade of measurements in India, is presented. Indian paddy cultivation areas contain soils that have low to medium levels of soil organic carbon. The average seasonally integrated CH₄ flux (E _sif) values calculated from these measurements were 15.3 ± 2.6 g m^–2 for continuously flooded (CF), 6.9 ± 4.3 g m^–2 for intermittently flooded (IF) single aeration (SA) and 2.2 ± 1.5 g m^–2 for IF multiple aeration (MA) rice ecosystems. For CF and IF (MA) rice ecosystems having high soil organic carbon, without organic amendments, the CH₄ flux (E _sif) may be increased by 1.7 times relative to low soil organic carbon, whereas it may enhance by 5.3 for CF if amended organically. Organic amendment and high soil organic carbon paddy areas do not alter the methane budget estimates for India (3.6±1.4 TgY^–1) much, due to their small paddy harvested area. Methane estimated using average emission factors (E _sif) for all paddy water regimes, which include harvested areas having soils with high organic carbon and organic amendments, may give a budget of 5 TgY^–1 for India.     

Remote monitoring of different electrical parameters of multi-machine system using PC

This paper describes a PC based centralized monitoring of the running condition of a multi-machine system. This kind of monitoring from remote central location is one of the primary requirements in today’s era of automation. The convergence of embedded system like microcontroller/DSP/FPGA, etc., now-a-days, is adding a new dimension to enhance the capability of the PC based data acquisition. In this present approach, conditions of different parameters of each motor have been measured by dedicated microcontroller based hardware. All these units are connected in a network using bus topology. All parameters are communicated to a remote PC through this bus where user friendly state-of-the-art developed software stores it for display and analysis purposes.     

Influence of polymer viscosity on the morphological and opto‐electronic behavior of polysiloxane dispersed ferroelectric liquid crystal composite thin films

Poly(dimethyl)siloxanes of different viscosity have been synthesized by hydrolytic condensation of dimethyldichloro silane. Polysiloxane dispersed ferroelectric liquid crystal (PDFLC) composite films were prepared simultaneously by solvent induced and polymer induced phase separation techniques (SIPS and PIPS, respectively). These composite films were prepared by mixing polymer and ferroelectric liquid crystal mixture in diethyl ether and then adding 0.2% of room temperature vulcanizer for crosslinking. Film morphology, droplet size, and electro‐optic parameters of PDFLC systems have been studied by using polysiloxanes of different viscosity. We show that the polymer viscosity affects the droplet size, morphological uniformity, electro‐optic properties, and also the extent to which the phase separation is complete. These composite systems show the switching time of few microseconds. Structure‐property correlation in these materials have been studied and explained on the basis of polysiloxane viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 159–166, 2004     

Ultracentrifugal studies of the degradation of a fracturing fluid polymer: Hydroxypropyl guar

Ultracentrifugal techniques have been employed to investigate the degradation of hydroxypropyl guar (HPG) solutions, and of gels formed with a delayed zirconium cross-linker, by ammonium persulphate at 90°C. Molecular weights, M, for various samples of degraded polymer were determined by sedimentation/diffusion, and an empirical relationship was established between M and the sedimentation coefficient at a single, low concentration. This enabled the straightforward determination of M as functions of persulphate concentration, cross-linker concentration, and time at temperature. It was shown that large decreases in M occur within the first hour at temperature, but that complete degradation is not achieved. It was further shown that, when a delayed zirconium cross-linker is used, degradation may be less effective when gels are formed and degraded at high shear rates.     

Background estimation and motion saliency detection using total variation-based video decomposition

As human vision system is highly sensitive to motion present in a scene, motion saliency forms an important feature in a video sequence. Motion information is used for video compression, object segmentation, object tracking and in many other applications. Though its applications are extensive, accurate detection of motion in a given video is complex and computationally expensive for the solutions reported in the literature. Decomposing a video into visually similar and residual videos is a robust way to detect motion salient regions. The existing decomposition techniques require large execution time as the standard form of the problem is NP-hard. We propose a novel algorithm which detects the motion salient regions by decomposing the input video into background and residual videos in much lesser time without sacrificing the accuracy of the decomposition. In addition, the proposed algorithm is completely parallelizable that ensures further reduction in computational time with the use of advanced multicore processors.     

Synthesis and characterization of polysiloxanes for controlled release of 2-pyridine aldoxime–chloride

A number of polysiloxanes and their copolymers were synthesized by hydrolytic polycondensation of dialkyl (ary) dichlorosilane or their mixtures in a saturated solution of NaCl in water at low temperature (0–5°C). These polysiloxanes were characterized by intrinsic viscosity, infrared and nuclear magnetic resonance spectroscopy. 2-Pyridine aldoxime–chloride (PAM–Cl) was incorporated into these polysiloxanes, followed by crosslinking with tetraethoxysilane using dibutyltindilaurate as catalyst. The effect of pH on in vitro release rate of PAM–Cl from polysiloxane matrices was investigated in phosphate buffer of pH 3.0, 7.4, and 10.0 at 37°C using an ultraviolet spectrophotometer. Transport parameters like the order of release and diffusion coefficients for these systems (polysiloxane—PAM–Cl) were also calculated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1837–1846, 1998     

Poly (2-hydroxyethyl methacrylate)-based hydrogels for slow release of pralidoxime chloride

Pralidoxime chloride (PAM-Cl)-loaded poly (2-hydroxyethyl methacrylate) (PHEMA)-based hydrogels were prepared by bulk copolymerization of 2-hydroxyethyl methacrylate (HEMA) with different mol fractions (0.02–0.10) of trimethylsilyl methacrylate. Characterization of the gels was done by dynamic swelling measurements. It was found that copolymerization does not alter the swelling mechanism of PHEMA and it essentially remains Fickian in nature. In vitro drug-release studies show the increase in release time from 6 to 12 h on incorporation of a 0.1 mol fraction of trimethylsilyl methacrylate on the PHEMA backbone. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 267–270, 1997     

Hybrid optical-electrochemical electronic nose system based on Zn-porphyrin and multi-walled carbon nanotube composite

In this work, we have enhanced the capability of an e-nose system based on combined optical and electrochemical transduction within a single gas sensor array. The optical part of this e-nose is based on detection of the absorption changes of light emitted from eight light emitting diodes (LEDs) as measured by a CMOS photo-detector. The electrochemical part works by measuring the change in electrical resistivity of the sensing materials upon contact with the sample vapor. Zinc-5,10,15,20-tetra-phenyl-21H,23H-porphyrin (ZnTPP) and multi-walled carbon nanotube (MWCNT) composite was used as the sensing materials based on its good optoelectronic properties. This sensing layer was characterized by UV-Vis spectroscopy and atomic force microscope and tested with various VOC vapors. Density functional theory (DFT) calculations were performed to investigate the electronic properties and interaction energies between ZnTPP and analyte molecules. It can be clearly seen that this hybrid optical-electrochemical electronic nose system can classify the vapor of different volatile organic compounds.     

Morphology and properties of nylon 6 and high density polyethylene blends in presence of nanoclay and PE‐g‐MA

In this study, we report the synergistic effect of nanoclay and maleic anhydride grafted polyethylene (PE‐g‐MA) on the morphology and properties of (80/20 w/w) nylon 6/high density polyethylene (HDPE) blend. Polymer blend nanocomposites containing nanoclay with and without compatibilizer (PE‐g‐MA) were prepared by melt mixing, and their morphologies and structures were examined with scanning electron microscopy (SEM) and wide angle X‐ray diffractometer (WAXD) study. The size of phase‐separated domains decreased considerably with increasing content of nanoclay and PE‐g‐MA. WAXD study and transmission electron microscopy (TEM) revealed the presence of exfoliated clay platelets in nylon 6 matrix, as well as, at the interface of the (80/20 w/w) nylon 6/HDPE blend–clay nanocomposites. Addition of PE‐g‐MA in the blend–clay nanocomposites enhanced the exfoliation of clays in nylon 6 matrix and especially at the interface. Thus, exfoliated clay platelets in nylon 6 matrix effectively restricted the coalescence of dispersed HDPE domains while PE‐g‐MA improved the adhesion between the phases at the interface. The use of compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012