Showing papers in "Journal of the Indian Institute of Science in 2013"

Estimation of Signal Parameters via Rotational Invariance Techniques- ESPRIT

Abstract: A new approach to the general problem of signal parameter estimation is described. Though the technique ESPRIT is discussed in the context of direction-of arrival estimation, it can be applied to a wide variety of problems including spectral estimation. ESPRIT exploits an underlying rotational invariance among signal subspaces induced by an array of sensors with a translational in variance structure (e.g., pairwise matched and co-directional antenna element doublets) and has several advantages over earlier techniques such as MUSIC including improved performance, reduced computational load, freedom from array characterization calibration, and reduced sensitivity to array perturbations. Results of computer simulations carried out to evaluate the new algorithm arc presented.

Defluoridation of water using inexpensive adsorbents

Abstract: The study assesses the suitability of inexpensive leaf adsorbents to effectively remediate fluoride-contaminated water. The efficiency of the sorption of fluoride ion is affected by pH, contact time, adsorbent dose, type and size of adsorbents and initial fluoride ion concentration. The adsorption equilibrium is well correlated by Freundlich and Langmuir models. Treated leaf powder was studied at various pHs (2, 4, 6 and 8) with a series of aqueous solutions containing 2, 3, 5, 6, 8, 10, 12, and 15 mg F/l. At the highest F-ion concentration (15 mg/l), the F-ion level in the effluent gradually decreased to 0 mg/l within 180 min at 29 +or-.5 degrees C when the dose of adsorbent is 10 g/l in a sample of 50 ml volume. With lower F- ion concentrations (2 mg/l) in the feed solutions the fluoride ion concentration steadily decreased reaching 0 mg/l after 150 min. Langmuir isotherm fits well for defluoridation of water using leaf powder.

FGM and Laminated Doubly-Curved and Degenerate Shells Resting on Nonlinear Elastic Foundations: A GDQ Solution for Static Analysis with a Posteriori Stress and Strain Recovery

Abstract: This work focuses on the static analysis of functionally graded (FGM) and laminated doubly-curved shells and panels resting on nonlinear and linear elastic foundations using the Generalized Differential Quadrature (GDQ) method. The First-order Shear Deformation Theory (FSDT) for the aforementioned moderately thick structural elements is considered. The solutions are given in terms of generalized displacement components of points lying on the middle surface of the shell. Several types of shell structures such as doubly-curved shells (elliptic and hyperbolic hyperboloids), singly-curved (spherical, cylindrical and conical shells), and degenerate panels (rectangular plates) are considered in this paper. The main contribution of this paper is the application of the differential geometry within GDQ method to solve doubly-curved FGM shells resting on nonlinear elastic foundations. The linear Winkler-Pasternak elastic foundation has been considered as a special case of the nonlinear elastic foundation proposed herein. The discretization of the differential system by means of the GDQ technique leads to a standard nonlinear problem, and the Newton-Raphson scheme is used to obtain the solution. Two different four-parameter power-law distributions are considered for the ceramic volume fraction of each lamina. In order to show the accuracy of this methodology, numerical comparisons between the present formulation and finite element solutions are presented. Very good agreement is observed. Finally, new results are presented to show effects of various parameters of the nonlinear elastic foundation on the behavior of functionally graded and laminated doubly-curved shells and panels.

An Overview and Some Challenges in Cyber-Physical Systems

Abstract: Technological advances in computing, communications, andcontrol, have set the stage for a next generation of engineered systems,called cyber-physical systems (CPS). These systems can potentially beimportant in overcoming many challenges in energy, environment, transportation,and health care. In this paper, we discuss some of these grandchallenges that necessitate further advances in CPS. We also provide apartial survey of some important research issues, and an overview of severalresearch efforts that have been undertaken toward the developmentof CPS.

Remote Sensing Applications in Water Resources

Abstract: With the introduction of the earth observing satellites, remote sensing has become an important tool in analyzing the Earth’s surface characteristics, and hence in supplying valuable information necessary for the hydrologic analysis. Due to their capability to capture the spatial variations in the hydro-meteorological variables and frequent temporal resolution suffi cient to represent the dynamics of the hydrologic processes, remote sensing techniques have signifi cantly changed the water resources assessment and management methodologies. Remote sensing techniques have been widely used to delineate the surface water bodies, estimate meteorological variables like temperature and precipitation, estimate hydrological state variables like soil moisture and land surface characteristics, and to estimate fl uxes such as evapotranspiration. Today, near-real time monitoring of fl ood, drought events, and irrigation management are possible with the help of high resolution satellite data. This paper gives a brief overview of the potential applications of remote sensing in water resources.

Hypersurfaces of a Riemannian manifold with semiSlmmetric non-metric connection

Abstract: Extending the work of Agashe and Chafle on semi-symmetric non-metric connection on a Riemannian manifold, we Study !he properties of hypersurfaces of a Riemannian manifold with a semi-symmetric non-metric connection

Temporal Issues in Cyber-Physical Systems

Abstract: This paper reviews the use of time, clocks, and clock synchronization protocols in cyber-physical systems (CPS). Recent advances in the area of timing suggest avenues of research and potential new application areas. We discuss how introducing timestamps and clocks can help overcome issues such as latency, jitter, and determining correct execution order. Furthermore, we show how system complexity can be reduced and distribution as well as parallelism can be done deterministically. We also point to recent work in raising time to first class citizen status in modeling and implementation. In particular, we describe design and execution environments of CPS and specialized hardware such as predictable timing architectures where time plays a key role.

Numerical modeling of contaminant transport using HYDRUS and its specialized modules

Abstract: A broad range of numerical models have been developed during the past several decades to describe the fate and transport of agricultural, industrial, and other contaminants in soils and groundwater. Such models are now increasingly implemented in both research and engineering projects addressing subsurface pollution problems. Of particular concern is especially non-point source pollution stemming from plant and animal production. In this paper we first briefly review different types of mathematical models that are being used to describe the transport of agricultural chemicals in both the vadose zone and groundwater. We next review various versions of the HYDRUS computer software packages, including several specialized modules that were recently developed for simulating the movement of water, heat, and solutes in the subsurface. Early versions of the HYDRUS models considered the transport of only one chemical species and assumed that the behavior of this solute was independent of other species present in the soil solution. Physical nonequilibrium transport could be accounted for in later versions of HYDRUS by assuming a two-region or dual-porosity type formulations that partition the liquid phase into mobile and immobile regions. Chemical nonequilibrium transport could be accounted for by assuming kinetic interactions between solutes in the liquid and solid phases. Physical and chemical nonequilibrium formulations were extended later also to particle transport by including provisions for filtration theory, and time- and/or depthdependent blocking functions. Subsequent versions of the HYDRUS codes also considered the transport of multiple solutes, which either could be coupled by means of a unidirectional first-order degradation chain, or move independently of each other. While this approach proved effective for evaluating the subsurface transport of many chemicals (e.g., nitrogen species, pesticides, radionuclides), many environmental problems require analyses of the transport of multiple chemical species that could interact mutually, create complexed species, precipitate, dissolve, and/or compete with each other for sorption sites. Several specialized modules have now been developed to simulate transport processes not accounted for in the earlier standard versions of HYDRUS. These include a wetlands module, the HP1/2/3 multicomponent transport modules, the facilitated transport C-Ride module, a modulefor fumigants, and the major ion Unsatchem module. All of these modules simulate flow and transport processes in two-dimensional transport domains and are supported by the HYDRUS (2D/3D) graphical user interface. Many processes of these specialized modules are also available as part of the public domain HYDRUS-1D software. Brief overviews of these more recent modules are included in this manuscript.

Degradation of azo dye with horse radish peroxidase (HRP)

Abstract: Azo dyes are recalcitrant carcinogenic compounds and have dermal and immunological effect on human beings. Conventional methods are not effective in the treatment of azo dyes. The oxidation capability of horse radish peroxidase (HRP) and hydrogen peroxide (H2O2) on direct yellow 12 dye was investigated and was found to be very effective treatment methodology. HRP was extracted from horse radish roots, and its performance was evaluated in soluble and immobilized form by conducting batch experiments in the presence of H2O2. The oxidation of direct yellow-12 dye was tested as a function of HRP at fixed concentration of H2O2, and at constant HRP activity (1.8 units/ml). Parameters such as aqueous-phase pH, H2O2 concentration, dye and enzyme concentrations were studied.

A survey of routing algorithms for wireless sensor networks

Abstract: Distributed wireless sensor networks consist of a large number of small, low-cost and low-power nodes (called motes) that coordinate with one another for environmental sensing. The sensor nodes are severely restricted in power, memory and computational resources. The nodes can be densely deployed in close proximity to the phenomenon to be observed. They can be deployed in hostile environments where the nodes may not be physically accessible and are subject to tampering. Nodes can be added to and deleted from the network at any time, resulting in unpredictable changes to the topology of the network. This presents new challenges in the design of routing protocols for sensor networks. In this paper, the constituent building blocks of sensor network routing protocols are identified and analyzed. The routing protocols are broadly classified into two categories: flat and hierarchical, and further into subcategories based on the centrality of their theme. Several routing algorithms belonging to each category that have been proposed in the literature are explored. The techniques used to achieve convergence and to eliminate routing loops are highlighted. Further the open problems in each algorithm are mentioned briefly. The paper concludes with a comprehensive comparison of the protocols based on several parameters.

Software Platforms for Internet of Things and M2M

Abstract: The technologies and applications consolidated under the vision of Internet of Things (IoT) and Machine to Machine Communications (M2M) are attracting the interest of businesses and poised to trigger next disruption in Information & Communication Technology (ICT) applications. The domain specific solutions involving sensors, mobile phones and other devices are maturing to integrate in a generic ICT services paradigm. Architecture for a unified horizontal services platform is emerging. This paper surveys important trends, key requirements, evolving technologies and emerging solutions for such a software platform for IoT and M2M services.

Triangle comparison and space vector approaches to pulse width modulation in inverter - fed drives

Abstract: This paper investigates the equivalence of the two popular approaches to pulsewidth modulation (PWM) in induction motor drives, namely, the triangle comparison approach and the space vector approach. It brings out the conditions wherein they are equivalent and wherein they are not. It shows that the space vector approach is more general and offers more degrees of freedom compared to the triangle comparison approach. Even a limited exploitation of these flexibilities has been reported to have improved the drive performance significantly. This gives adequate motivation to exploit these flexibilities further.

Centralized PI/PID controllers for nonsquare systems with RHP zeros

Abstract: Two centralized controller-tuning methods, Davison's method [Multivariable tuning regulators: The feed forward and robust control of general servo mechanism problem, IEEE Trans. Auto. Control, 21, 35-21 (1976)] and Tanttu and Lieslehto method [A comparative study of some multivariable PI controller tuning methods, in Intelligent tuning and adaptive control, Pergamon Press, pp 357-362 (1991)], are extended to nonsquare systems with right half-plane zeros. These methods have been applied to two examples with right half-plane zeros in the individual scalar elements-coupled pilot plant distillation columns (2 outputs and 3 inputs) and a crude distillation process (4 outputs and 5 inputs). Simulation studies have been carried out for these examples for both servo and regulatory problems. For the coupled pilot plant distillation column example, the proposed methods are compared with the robust decentralized controller design method proposed by Loh and Chiu [Robust decentralized control of nonsquare systems, Chem. Engng Commun., 158, 157-180 (1997)]. The performance of square and nonsquare controllers is compared for the crude distillation process example.

Skew angle detectionof a cursive handwritten Devanagari script character image.

Abstract: This paper proposes an accurate and exhaustive approach to detect the skew angle of the images of words/ characters of cursive Devanagari script. This approach was applied to 235 writing samples and a total collection of around 6000 samples. It is efficient in terms of time and is a simpler process as compared to the existing ones. The method is an extension to the work of Pal and Chaudhuri [B. B. Chaudhuri and U. Pal, Skew angle detection of digitized Indian script documents, IEEE Trans. PAMI-19, 182-186 (1997)]. Heuristic approach has been applied to detect the skew angle. The inherent dominating features of the structure of the Devanagari script have been used to accurately calculate the skew of the Devanagari word.

Structural Health Monitoring of Composite Aircraft Structures Using Fiber Bragg Grating Sensors

Abstract: Aircraft industry is continually striving towards reducing the acquisition, operation and maintenance costs. Usage of advanced composite materials in primary aircraft structures have resulted in significant weight savings owing to their higher specific strength and specific stiffness. Composite structures, in spite of their inherent advantages, are prone to various damages. To detect and repair various structural damages that can occur during the service life of the aircraft, a thorough inspection schedule is implemented through conventional visual and Non Destructive Evaluation methods. Such scheduled inspections lead to considerable increase in maintenance cost & down-time of the aircraft. An online structural health monitoring (SHM) system consisting of well-designed sensor networks incorporated in the structure along with necessary hardware and software can provide information about the structure, thereby leading to reporting of flaws or damages in real time. Such a system can provide inputs for condition based maintenance which can result in reduced maintenance cost. This paper presents the work carried out at CSIR-National Aerospace Laboratories towards developing a flight-worthy SHM system and its demonstration on an unmanned aerial vehicle (UAV). Sensor selection, characterization, instrumentation design, algorithm development towards damage detection & load estimation at lab level and implementation of the technology on a UAV are discussed in this paper.

Synthesis and structure revision of intensely sweet saponin, osladin

Abstract: The total synrhesis of compound 10, which is the reported structure of intensely sweet saponm oaladin, has been completed.However, it is not as sweet as suggested Re-extraction of the sweet principle of rhizomes of the fern Polypodium vulgare (Polypodiaceae) and single crystal X-ray diffraction study revealed its real structure to be 27. We also found it to be only 500 tunes sweeter than sucrose as against 3,000 tones suggested elsewhere. Therefore, the tolal synthesis, of the real osladin was achieved from steroidal aldehyde 20 by using newly developed beta-selective and 2' hydroxyl group-discriminated glucosylation procedure and our original alpha-selective thermal rhamnosylation reaction. Synthetic osladin was also very sweet and thus we prove that osladin is the real sweet principle of the fern.

Optimal Design of Composite Structures: A Historical Review

Abstract: Composites are widely used in aerospace structures; however, most designs do not exploit the inherent tailorability of composites. Optimization methods can be used to design composite structures by tailoring the ply angles and stacking sequences. Typical objectives include minimum weight and constraints include strength, buckling, displacements and frequencies. This paper covers some of the literature in the area, with the objective of understanding the historical evolution of the field. Some ideas for future research are provided. It is hoped that the review will provide new researchers with a basic idea about the growth of the field and point them towards useful references for further information.

Fibre-reinforced metal matrix composites --a review

Abstract: In recent years, there has been an increasing demand from automotive, space and aeronautical industries for materials possessing high specific strength, better wear resistance and stability at high temperatures. The process of improving the properties of conventional engineering materials has led to the technique of reinforcing polymers, ceramics and metals with particles, fibres and whiskers, thus leading to the production of composites. Because of the higher ductility and ease of fabrication than ceramic matrix composites (CMCs) and better environmental stability and stiffness than polymer matrix composites (PMCs), metal matrix composites (MMCs) have become popular and are widely used. This paper outlines the various production techniques and mechanical properties of MMCs. Further, it shows that Al and Zn-based oarnposites exhibit tremendous improvement in all mechanical properties as compared to the unreinforced base alloy.

A simple alias-free QMF system with near-perfect reconstruction

Abstract: This paper presents a design of prototype filters for quadrature mirror filter (QMF) banks. To minimize the value of reconstruction error for near-perfect reconstruction (NPR), linear optimization has been applied. Variable and combinational window functions with high side-lobe-fall-off-rate (SLFOR) have been used to design lowpass prototype filters. Use of window functions resulted in simple implementation. High SLFOR of combinational windows reduced the energy leakage due to aliasing from one sub-band to the other. The proposed optimization algorithm takes a few seconds on Pentium processor.

Al-doped zinc oxide (ZnO:Al) thin films by pulsed laser ablation.

Abstract: Highly conductive and transparent aluminum-doped zinc oxide thin films were prepared by ablating the target containing 2 wt% Al2O3 with ArF excimer laser (lamda=193 nm). The films were grown at a repetition rate of 10 Hz, energy density of 2-3 J/cm2 and irradiation time of 10-60 min (6000-36000 laser shots). The optical and electrical properties of the films depend on the substrate temperature and oxygen pressure during film deposition. The lowest resistivity was found to be at 1.44 Wcm for films deposited at 300oC and in 1mtorr of oxygen ambient. The average transmittance was found to be in the range of 84-92%. Sharp decrease in transmittance and sharp increase in reflectance near the plasma edge in the near-infrared range are due to impurity scattering, which is caused by aluminum doping.

An adaptive neuro-fuzzy system for color image segmentation

Abstract: Image segmentation and object extraction plays an important role in image analysis and computer vision. In this paper, we propose a novel technique for color image segmentation called 'adaptive neuro-fuzzy color image segmentation (ANFCIS)'.The proposed system consists of multilayer perceptron (MLP)-like network which performs color image segmentation using multilevel thresholding. Threshold values for detecting clusters and their labels are found automatically using fuzzy C-means (FCM) clustering technique. Fuzzy entropy is used as a tool to decide the number of clusters. ANFCIS uses saturation and intensity planes of HSV (hue, saturation, intensity) color space for segmentation. Neural network is employed to find the number of objects automatically from an image. The major advantage of this method is that it does not require a priori knowledge to segment a color image. The algorithm is found to be robust and relatively computationally inexpensive for large variety of color images. Experimental results have demonstrated the effectiveness and efficiency of the proposed method.

Regionalization of Precipitation in India – A Review

Abstract: Regionalization of precipitation refers to delineation of rain gauges in an area into homogeneous groups (clusters or regions). Various regionalization procedures are employed by researchers in hydro-meteorology for addressing a wide spectrum of problems. This paper provides an overview of underlying concepts as well as advantages and limitations of procedures that have been developed over the past six decades. Emphasis is given to studies that have been carried out in India. Following this, gaps where more research needs to be focussed are highlighted, and challenges for regionalization in a climate change scenario are discussed.

Distributed Control for Cyber-Physical Systems

Abstract: Networked Cyber-Physical Systems (CPS) are fundamentallyconstrained by the tight coupling and closed-loop control and actuationof physical processes. To address actuation in such closed-loop wirelesscontrol systems there is a strong need to re-think the communication architecturesand protocols for maintaining stability and performance in thepresence of disturbances to the network, environment and overall systemobjectives. We review the current state of network control efforts forCPS and present two complementary approaches for robust, optimal andcomposable control over networks. We first introduce a computer systemsapproach with Embedded Virtual Machines (EVM), a programmingabstraction where controller tasks, with their control and timing properties,are maintained across physical node boundaries. Controller functionalityis decoupled from the physical substrate and is capable of runtime migrationto the most competent set of physical controllers to maintain stabilityin the presence of changes to nodes, links and network topology. We then view the problem from a control theoretic perspective todeliver fully distributed control over networks with Wireless Control Networks(WCN). As opposed to traditional networked control schemes wherethe nodes simply route information to and from a dedicated controller, ourapproach treats the network itself as the controller. In other words, thecomputation of the control law is done in a fully distributed way inside thenetwork. In this approach, at each time-step, each node updates its internalstate to be a linear combination of the states of the nodes in its neighborhood.This causes the entire network to behave as a linear dynamicalsystem, with sparsity constraints imposed by the network topology. Thiseliminates the need for routing between “sensor → channel → dedicatedcontroller/estimator → channel → actuator”, allows for simple transmissionscheduling, is operational on resource constrained low-power nodesand allows for composition of additional control loops and plants. Wedemonstrate the potential of such distributed controllers to be robust to ahigh degree of link failures and to maintain stability even in cases of nodefailures.

Cycloconverters and cycloconverter-fed drives :A review

Abstract: Significant developments have taken place in control, analysis, modelling and practical implementation aspects of cycloconverters and their applications to the adjustable-speed ac drives. This paper attempts to make a comprehensive and chronological review on the progress of research and industrial development, all over the world, to provide a background information on the present status of cycloconverters and cycloconverter-fed drives. In the process, it highlights the substantial research work done at the Indian Institute of Technology (lIT), Kharngpur towards developing practical control schemes and simulation models for cycloconverter-fed induction and synchronous motor drives.

On the prediction of packet process in network traffic using FARIMA time-series model

Abstract: The simultaneous existence of short- and long-range dependence in the network traffic has exposed the limita-tions of conventional traffic models. In this paper, we suggest fractionally integrated autoregressive moving aver-age process (FARIMA) to model the packet process observed in network traffic. We have used different levels of aggregations for computing differencing parameter d. We also give the complete procedure for modeling and obtaining the predictions for packet process in network traffic using the FARIMA (p, d, q) model. Keywords: SRD, LRD, FARIMA.similar lines, with increase through successive larvae. Both consumption index (CI) and growth rate (GR) de-clined as the larvae aged, the value of the former averaging 3.02 and the latter 0.37. The values of approximate digestibility (AD) are high: 9987%. The values of both efficiency of conversion of ingested food (ECI) and effi-ciency of conversion of digested food (ECD) increased as the larvae aged, the former averaging 18.02% and the latter 22.26%. Adults of P. hector utilized nearly 24 floral species as nectar sources, whose sugar concentrations (1258%) corresponded with 1550% in psychophilic flowers. They displayed a hovering habit while harvesting nectar, and frequently contacted the essential organs with probosics and head, thus promoting cross-pollination.

Bidirectional optical fiber transmission scheme through Raman amplification: Effect of pump depletion

Abstract: In this paper, we have presented the comparative study of bidirectional optical fiber transmission scheme for various cases using Raman amplification process with and without pump depletion. Signal power amplification, pump depletion effect and equivalent fiber loss are discussed for various cases. The results are compared.

Hybrid Automata for Formal Modeling and Verification of Cyber-Physical Systems

Abstract: The defining feature of a cyber-physical system(CPS) is the presence of a tight integration of the discrete control(the “cyber”) with the analog environment (the “physical”) viasensors and actuators over wired or wireless communicationnetworks. Hence the functional correctness of a CPS is cruciallydependent not only on the dynamics of the analog physicalenvironment, but also on the decisions taken by the discretecontrol that alter the dynamics of the environment. The frameworkof Hybrid automata—introduced by Alur, Courcoubetis,Henzinger, and Ho—provide a formal model and specificationlanguage to analyze the interaction between the discrete andcontinuous parts of a cyber-physical system. Hybrid automatacan be considered as generalizations of finite state automataaugmented with a finite set of real-valued variables whosedynamics in every state is governed by a set of differentialequations. Moreover, discrete transitions of hybrid automataare guarded by constraints over the values of these real-valuedvariables, and enable discontinuous jumps in the evolution ofthe real-valued variables. Considering the richness of alloweddynamics in a hybrid automata, it is perhaps not surprisingthat the fundamental verification questions, like reachability, areundecidable in general. In this paper we concentrate on thereachability problem for hybrid automata and precisely characterizevarious boundaries between decidable and undecidablesub-classes of hybrid automata.

Power system static security assessment using self-organizing neural network.

Abstract: Artificial neural network approach to the problem of static security assessment of power system is presented. This paper utilizes the artificial neural net of Kohonen's self-organizing feature map (SOFM) technique that transforms input patterns into neurons on the two-dimensional grid to classify the secure/insecure status of the power system. SOFM uses the line flows under different component cases as inputs and self-organizes to obtain the cluster of the components based on their loading limits. The output of SOFM provides information about the violation of the constraints from which the operating state of the power system can be identified, which can be classified as secure or insecure. The proposed method of security assessment was initially demonstrated for a model 3 generator 6-bus system and later extended to IEEE-14, -30 and -57 bus systems.

Freshwater rotifers (Rotifera: Eurotatoria) from some domestic wells in West Bengal, India

Abstract: Rotifer communities of 25 domestic wells in South 24-Parganas District, West Bengal, are made up of nine species belonging to six genera and five families. Comments are made on their species composition. The present report of Myulina bisulcata from these pristine environs is considered to be of special ecological interest.