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      Volume 44, Issue 2

      February 2019

    • Flow periodicity and convection modes in rotating Rayleigh–Bénard convection at low Rayleigh numbers

      VISHNU VENUGOPAL T ARNAB KUMAR DE

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      A three-dimensional numerical study on rotating Rayleigh–Bénard convection of water in a cylindrical container with a specific aspect ratio is performed in the present work. The simulations are carried out at four different Rayleigh numbers (3 × 10⁴, 5 ×10⁴, 7 ×10⁴ and 10⁵) and a fixed Prandtl number (Pr = 7) for a range of rotation rates. Flow structures and their evolution with the addition of rotation to the system are studied in detail. Emphasis is given on the analysis of wall mode and bulk mode convection that appear at different rotation rates. The changes in heat transfer and stability of the system are also investigated. Heattransfer rate is measured by calculating the average Nusselt number at the hot wall. The results show that rotation primarily has an inhibiting effect on heat transfer. For Ra≤7 × 10⁴ the decrease in heat transfer is negligible at lower rotation rates, while it declines steeply for higher rotation rates. At Ra =10⁵ a small increase in Nusselt number is obtained at low rotation rates before it drops at higher rotation rates. Numerous probes placed at different points within the flow domain are used to investigate the flow regimes and convection modes. The flow initially remains steady at low rotation rates and transforms to a periodic stage with bulk-mode dominated convection at moderate rotation rates. Further increase in rotation gives a wall mode convection accompanied by a drastic drop in heat transfer rate before finally approaching a static conductive stage. The dual role of rotation on the stability of Rayleigh–Bénard convection is clearly identified in the present study. At moderate rotation rates, the rotation force destabilizes the system to reach a periodic flow whereas extremely large rotation rate stabilizes it.

    • Joint medical image compression–encryption in the cloud using multiscale transform-based image compression encoding techniques

      S P RAJA

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      The recent years have witnessed rapid strides in the use of cloud computing and its countless applications. A cloud can contain massive volumes of multimedia data in the form of images, video and audio. Cloud computing platforms confront challenges in terms of data confidentiality, message integrity, user authentication and compression. Multimedia data needs plenty of storage capacity. Consequently, there is a need for multimedia data compression to reduce data size. Compression techniques are quite reliable, offering benefits to organizations dealing with metasized data in the cloud. Compressing large quanta of data leads to superior utilization of cloud storage. Compression techniques can compress data used for storage and transmission, yet compression alone is inadequate because multimedia data shared should, of necessity, be secure. Therefore, both multimedia compression and security are mandatory in the cloud. The chief goal ofthis paper is to propose a new framework, comprising multiscale transforms, public key cryptography and appropriate encoding techniques, that performs joint medical image compression and image encryption in the cloud. Multiscale transforms play a lead role in image compression, and the ones discussed in this paperinclude wavelet, bandelet, curvelet, ridgelet and contourlet transforms. Wavelet transforms offer robust localization both in terms of time and frequency domains. Bandelet transforms offer natural images geometric regularity to help improve the efficiency of representation. Curvelet transforms handle curve discontinuitieswell, with ridgelet transforms being the core idea behind curvelets. Contourlet transforms capture smooth contours and edges at any orientation. The Rivest-Shamir-Adleman (RSA) algorithm is used to encrypt images to provide maximum security when they are being transferred. Encoding techniques involved in thispaper comprise the Embedded Zerotree Wavelet (EZW), Set Partitioning in Hierarchical Trees (SPIHT), Wavelet Difference Reduction (WDR), and Adaptively Scanned Wavelet Difference Reduction (ASWDR). Performance parameters such as peak signal to noise ratio (PSNR), mean square error (MSE), image qualityindex and structural similarity index (SSIM) are used for evaluation. It is justified that the proposed framework compresses images securely in the cloud.

    • A new representation of polygonal curves based on piecewise-linear functions with potential application in shape identification

      VICTOR M JIMENEZ-FERNANDEZ ENRIQUE VALDES-ORTEGA JOSE A MARTINEZ-MELCHOR HECTOR VAZQUEZ-LEAL URIEL A FILOBELLO-NINO NORBERTO CARRILLO-RAMON

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      In this paper, a new representation of polygonal curves is proposed. The motivation behind this proposal is to find a descriptive model with potential application in shape identification. In particular, our work addresses the problem of identifying the shape of a given polygonal curve from a set of different ones. Inaccordance with the proposed representation, a curve is originally described as a series of consecutive points whose connection by straight lines sketches its characteristic shape. In order to define a proper identification scheme, each series of points is mapped to a one-dimensional piecewise-linear function that assigns to each point its corresponding angle. Depending on the case under study, this assignation is performed by following two possible alternatives: (i) in the case where the shape to be identified exactly corresponds with one of thepreviously stored ones, a sorted sequence beginning from the minimum value of angle and ending with the maximum one is considered, and (ii) in the case where the shape to be identified is similar to one of the previously stored ones, the assignation is performed by following the sequence of points as they appear in thepolygonal curve (without sorting). Under this scheme of representation, by a cyclic comparative process between the computed functions, after several steps it is decided whether the graph of any input piecewise-linear function matches the polygonal curve to be recognized within a certain tolerance. In particular, in the case of the identification of two equal shapes, this proposal exploits the well-known principle of similarity geometry, which allows a polygon to be recognized independently of scale, translation and rotation. In order to validate thisrepresentation, a comparative analysis between two different shape identification methods (Fourier descriptors and canonical representation) and the piecewise-linear proposal is performed.

    • Estimation of manufacturing systems degradation rate for residual life prediction through dynamic workload adjustment

      V K MANUPATI SURAJ PANIGRAHI MUNEEB AHSAN SOMNATH LAHIRI AKSHAY CHANDRA J J THAKKAR GORAN PUTNIK M L R VARELA

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      Complex systems in a work cell often consist of multiple units to process the manufacturing functions effectively for achieving the desired objectives. All manufacturing work cells are familiar with many unforeseeable events, for instance machine down time and scheduled maintenance. In fact, every configurationnaturally exhibits some level of redundancy during those unpredictable events that may fail a small portion of units. In this work, using the remaining units and by raising the workloads on these units, up to the level of their capacities, we tried to fulfil the requirement of products. To procure the requirement, dynamic workloadadjustment strategy has been suggested on two important configurations such as parallel and hybrid, by actively controlling its degradation path and failure times. During its operation, at each decision-making point, termed as decision epoch, the examination of the real-time condition monitoring data has been carried out for upgrading the posterior distribution. Using this updated distribution as the root of all operations, the residual life distribution of every concerned unit is calculated, for a particular workload. Subsequently, the establishment of an optimization scheme, i.e., an optimization framework, has been carried out with the help of the predictedresidual life to eliminate the unit failures, for individual units, coinciding with each other. Eventually, with various scenarios, simulation has been carried out on the proposed methodology to assess the rate of degradation of various units. The validation of the approach’s effectiveness has been shown by the simulation results on two different configurations having different scenarios.

    • Three-dimensional numerical study on aerodynamics of non-flapping bird flight

      AMIT SONI SHALIGRAM TIWARI

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      Numerical investigations have been carried out to study aerodynamics of non-flapping characteristics of bird flight. Commercial software ANSYS Fluent 16.1 has been used for three-dimensional computations by considering four types of wing models. At first, square prisms with built-in side flaps are considered and theeffects of Reynolds number (Re), angle of attack and dihedral angle on flow characteristics have been investigated. Thereafter, flow past actual bird wing has been considered for wings of owl, seagull, teal and bat. Role of shear layer formation at mid-span of wings has been illustrated with the help of streamline plots for different values of Re. In addition, pulsating flow is imposed on inlet velocity and the responses are obtained in form of force coefficients, phase portraits, time-dependent signals and their spectra.

    • Limitations of Flight Path Reconstruction techniques

      C KAMALI EROL OZGER

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      The Flight Path Reconstruction (FPR) techniques are performed to verify the data compatibility check and post-flight. This is often achieved by calibrating the onboard sensors such as inertial and airdata sensors. In this paper, the limitations of FPR techniques in terms of Maximum Likelihood Estimation (MLE) andExtended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) have been reported. To demonstrate the FPR and sensor calibration, kinematic trajectory simulations with wind box type maneuvers have been performed. It is also shown as how a kinematic simulation is valid for the studies carried out in this work.

    • High-efficiency WLANs for dense deployment scenarios

      B T VIJAY B MALARKODI

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      In this article, we review the latest technical attributes such as orthogonal frequency division multiple access (OFDMA), multi-user MIMO (MU-MIMO) and enhanced clear channel assessment (CCA) for better spatial reuse used in the 802.11ax amendment to the 802.11 standard that leads to PHY and MACenhancements for high-density scenarios of access points (APs). IEEE 802.11ax, also referred to as highefficiency wireless local area network (WLAN) (HEW), provides mechanisms to thoroughly utilize the unlicensed spectrum bands (2.4 and 5 GHz) and strengthen the user experience. The functional requirements ofHEW are stressed on interactive video transmission latency and access efficiency to meet quality of service (QoS) requirements. Finally, we investigate three configurations—MU-MIMO, OFDMA and combination of both or mixed mode—for 4-user AP transmission schemes in 802.11ax. The performance of the MU schemes varies with packet size and operating SNR. OFDMA is more efficient than MU-MIMO at low SNRs for all packet sizes, which means 5th percentile stations (STAs) can get desired throughput.

    • Towards virtual machine introspection based security framework for cloud

      BHAVESH BORISANIYA DHIREN PATEL

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      Virtualization enables provision of resources to users according to their requirement through Infrastructure as a Service (IaaS) delivery model in cloud computing environment. Malicious users could lease cloud resources and use them as platforms to launch attacks. In this paper, we propose a Virtual MachineIntrospection (VMI)-based security framework to monitor cloud users’ in-VM activities and detect malicious one if any. We justify our selection of VMI method based on hardware knowledge for proposed framework by discussing its key advantages over other VMI methods. We propose design of multi-threaded analysis component that can introspect number of virtual machines hosted on cloud servers in real time. Experimental results demonstrate that our framework performs well with a set of metrics appropriate for cloud IaaS environment.

    • Three-dimensional flow separations on a rolling sphere

      PRAVIN K VEREKAR JAYWANT H ARAKERI

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      Experiments are conducted to study the flow separations on a sphere rolling on an inclined plane submerged in water. These experiments are performed at Reynolds numbers Re between 1350 and 1550. The experiments show that the flow separations on the surface of a rolling sphere can be organized into four distinctregions: (i) region of primary separation-I on the front upper sphere and extending below the poles, (ii) region of viscous blockage at the crevice surrounding the point of contact and shear layer separation ahead and at the sides of the viscous blockage, (iii) region of primary separation-II on the rear lower sphere and (iv) secondary separations on the rear upper sphere surface. The ratio of the width of the viscous blockage to the diameter of the sphere is found to be 0.4. Primary separation-I surface is symmetrical about the equatorial plane of the rollingsphere. Primary separation-II from the rear lower sphere surface is asymmetrical about the equator and eddies are shed alternately on either side of the equator from this separation surface. These lower eddies are energetic and dominate the dynamics of the wake. The upper eddy shedding from the primary separation-I surface and the lower eddy shedding from the primary separation-II surface are synchronized.

    • Analysis of generalized continual-clamp and split-clamp PWM schemes for induction motor drive

      SOUMITRA DAS V S S PAVAN KUMAR HARI ARUN KUMAR G NARAYANAN

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      Continual-clamp pulse width modulation (CCPWM) clamps each phase of a three-phase inverter to one of the two dc buses continually for 60°duration in each half of the fundamental cycle. Split-clamp pulse width modulation (SCPWM) divides the 60° clamping interval into two sub-intervals, which are not necessarily equal, and falling in two different quarter cycles. Whether continual clamp or split clamp, the positioning of the clamping interval in case of CCPWM, and the ratio of splitting the clamping interval in SCPWM – all influencethe waveform quality of the inverter output. This paper derives analytically closed-form expressions for the total RMS harmonic distortion factor and torque ripple factor pertaining to CCPWM with any arbitrary position of the clamping interval (i.e., generalized CCPWM) and also corresponding to SCPWM with any arbitrary ratio of splitting of the clamping interval (i.e., generalized SCPWM). The analytical results are well supported by experimental results on 3-hp and 5-hp induction motor drives.

    • A numerical study of natural convection properties of supercritical water (H₂O) using Redlich–Kwong equation of state

      HUSSAIN BASHA G JANARDHANA REDDY N S VENKATA NARAYANAN

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      In this article, the Crank-Nicolson implicit finite difference method is utilized to obtain the numerical solutions of highly nonlinear coupled partial differential equations (PDEs) for the flow of supercritical fluid (SCF) over a vertical flat plate. Based on the equation of state (EOS) approach, suitable equations arederived to calculate the thermal expansion coefficient (β) values. Redlich–Kwong equation of state (RK-EOS), Peng-Robinson equation of state (PR-EOS), Van der Waals equation of state (VW-EOS) and Virial equation of state (Virial-EOS) are used in this study to evaluate β values. The calculated values of β based on RK-EOS is closer to the experimental values, which shows the greater accuracy of the RK-EOS over PR-EOS, VW-EOS and Virial-EOS models. Numerical simulations are performed for H ₂O in three regions namely subcritical, supercritical and near critical regions. The unsteady velocity, temperature, average heat and momentum transport coefficients for different values of reduced pressure and reduced temperature are discussed based onthe numerical results and are shown graphically across the boundary layer.

    • Effect of post-weld heat treatment on the microstructure and tensile properties of electron-beam-welded 21st century nickel-based super alloy 686

      B ARULMURUGAN KUNJAN MODI AMRUTKAR PRANIT SANJAY PATIL APURVA YASHWANT N RICKWITH C G MOHAN P SUBRAMANI M AGILAN M MANIKANDAN N ARIVAZHAGAN

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      This work examines the influence of post-weld heat treatment (PWHT) on the fusion zone microstructure, and mechanical properties of electron beam (EB)-welded alloy 686. Comparative studies have been made on weld microstructure and tensile properties of the weldments both in as-welded and post-weldedheat-treated conditions. PWHT consists of direct aging (DA/480 °C for 3 h) and solution treatment (ST, 980 °C for 1 h) followed by ageing and finally, homogenizing treatment (HT, 1200 °C for 1 h) followed by DA and ST. The secondary topologically closed packed (TCP) phases formation, their distribution and microsegregation characteristics are studied with the aid of scanning electron microscope (SEM) analysis. Energy-dispersive X-ray spectroscopy (EDS) is also performed to estimate the microsegregation of alloying elements in thedendritic core and interdendritic regions of the weldments. The result shows that there is no significant change in the microstructure of DA and solution-treated sample as compared to the as-welded sample. The microstructureof HT sample was entirely different from those of as-welded and other HT samples. The SEM/EDS analysis illustrates the presence of secondary TCP phases (σ, P and μ) in the as-weld, DA and ST condition, whereas HT weldments did not show the presence of TCP phases. Tensile test results show higher tensile strength in ST condition whereas homogenization samples show higher ductility compared with others.

    • A mixed integer linear programming model for the vehicle routing problem with simultaneous delivery and pickup by heterogeneous vehicles, and constrained by time windows

      SAKTHIVEL MADANKUMAR CHANDRASEKHARAN RAJENDRAN

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      In this work, we consider the Vehicle Routing Problem with Simultaneous Delivery and Pickup, and constrained by time windows, to improve the performance and responsiveness of the supply chain by transporting goods from one location to another location in an efficient manner. In this class of problem, each customer demands a quantity to be delivered as a part of the forward supply service and another quantity to be picked up as a part of the reverse recycling service, and the complete service has to be done simultaneously in a single visit of a vehicle, and the objective is to minimize the total cost, which includes the traveling cost anddispatching cost for operating vehicles. We propose a Mixed Integer Linear Programming (MILP) model for solving this class of problem. In order to evaluate the performance of the proposed MILP model, a comparison study is made between the proposed MILP model and an existing MILP model available in the literature, with the consideration of heterogeneous vehicles. Our study indicates that the proposed MILP model gives tighter lower bound and also performs better in terms of the execution time to solve each of the randomly generatedproblem instances, in comparison with the existing MILP model. In addition, we also compare the proposed MILP model (assuming homogeneous vehicles) with the existing MILP model that also considers homogeneous vehicles. The results of the computational evaluation indicate that the proposed MILP model gives much tighter lower bound, and it is competitive to the existing MILP model in terms of the execution time to solve each of the randomly generated problem instances.

    • Mean centred clustering: improving melody classification using time- and frequency-domain supervised clustering

      CHANDANPREET KAUR RAVI KUMAR

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      This paper reports a new approach for clustering melodies in audio music collections of both western as well as Indian background and its application to genre classification. A simple yet effective new classification technique called mean centred clustering (MCC) is discussed. The proposed technique maximizesthe distance between different clusters and reduces the spread of data in individual clusters. The use of MCC as a preprocessing technique for conventional classifiers like artificial neural network (ANN) and support vector machine (SVM) is also demonstrated. It is observed that the MCC-based classifier outperforms the classifiers based on conventional techniques such as Principal Component Analysis (PCA) and discrete cosine transform (DCT). Extensive simulation results obtained on different data sets of western genre (ISMIR) and classicalIndian ragas are used to validate the efficiency of proposed MCC-based clustering algorithm and ANN/SVM classifiers based on MCC. As an additional endeavour, the performance of MCC on preprocessed data from PCA and DCT is studied. Based on simulation results, it is concluded that the application of MCC on DCT coefficients resulted in the highest overall classification success rate over different architectures of the classifiers.

    • Investigation of different inputs and a new release policy in the proposed simulation model for wafer fabrication system

      RASHMI SINGH M MATHIRAJAN

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      This paper investigates the effect of different inputs on selected performance metrics such as cycle time, WIP level and throughput in the processes of semiconductor wafer fab by developing a simulation model of representative but fictitious semiconductor wafer fab. The different inputs include arrival rate, arrival distribution, processing time, maintenance schedule, operator schedule, batch size, dispatching rule and release policy. Simulation results show that the relationship between inputs and system performance metrics, consideredin this study, are extremely complex particularly for the inputs maintenance schedule, operator schedule and batch size. An overall result shows that dispatching rule and closed loop release policy can significamtlyimprove the performance of wafer fabrication system. However; major improvement comes from closed loop release policy. Accordingly, this paper presents a new closed loop release policy called as constant batchmachine workload (CONSTBWL) to improve the performance of wafer fab. The behaviour of CONSTBWL is analysed in combination with dispatching rules using the proposed simulation model for wafer fab. Simulation results show that CONSTBWL policy outperformed traditional release policies in terms of the average cycle time, the work in process (WIP) level and the standard deviation of WIP level under a prescribed throughput level. Furthermore, the analysis of the results indicated that a good shop floor performance can be achieved witha right combination of closed loop release policy and simple dispatching rules with respect to the choice of performance metrics.

    • Detection of inclined edge crack in prismatic beam using static deflection measurements

      SUNIL R PANSARE SACHIN S NAIK

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      The effectiveness of a static deflection method for detection of an inclined edge crack in a prismatic cantilever beam is presented in this paper. A rotational spring is used to represent the flexibility due to the inclined crack. Two values of static deflections are needed for detection of crack location and rotational springstiffness. The spring is positioned at the crack tip. Twenty-one mild steel specimens with various crack inclinations, locations and depths are used for experimentation. The experimental results confirm that the staticdeflection measurements can be used to predict the crack location of an inclined edge crack with acceptable accuracy.

    • Crack initiation and propagation in coalbed gas reservoir during hydraulic fracturing

      TINGTING JIANG HAIWANG YE GAOFENG REN JIANHUA ZHANG YUBIAO LI JUNWEI WANG HAO WU CHUNYANG ZHANG GANG HUANG BO KE WEI LIU

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      The crack initiation and propagation calculation model during hydraulic fracturing in a coalbed methane reservoir with interlayers is established in this paper. The influence of coal elasticity modulus and fracturing fluid displacement on the fracture geometry are studied. Results show that the fracture initiationbegins at the perforation interval. Stress inhomogeneity is detrimental for the formation of multiple cracks for the extension of the fracturing area. The cracks at the boundary have changed from less developed to more developed with increasing horizontal stress coefficient. The coal elasticity modulus and fracturing fluid displacement both play a determinative effect on fracture geometry. The study provides a reference basis for implementing hydraulic fracturing of low permeability coal seams with interlayers.

    • Development of possibilistic statistics and its application to quantify uncertainty of subsurface solute transport model

      T K PAL D DATTA

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      Imprecise information on any system is addressed by possibility theory wherein the system is modeled as a fuzzy set. Alpha level representation of a fuzzy set in the form of an interval defines the possibility theory. Uncertainty of any model in this context is quantified as mean value ± standard deviation of a possibilistic(imprecise) parameter. This paper presents the possibilistic statistical techniques to estimate the mean and standard deviation of a possibilistic parameter of subsurface solute transport model. The solute transport model parameters, such as groundwater velocity, solute dispersion coefficient, etc., are sparse and imprecise in nature. Such parameters are characterized by the possibility distribution. In this paper, analytical expression of solute transport model is used to estimate the mean value and standard deviation of possibilistic spatial andtemporal concentration of solute.

    • Evolutionary computing based hybrid bisecting clustering algorithm for multidimensional data

      K APARNA

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      The emerging technologies and data centric applications have been becoming an integral part of business intelligence, decision process and numerous daily activities. To enable efficient pattern classification and data analysis, clustering has emerged as a potential mechanism that classifies data elements based onrespective feature homogeneity. Although K-Means clustering has exhibited appreciable performance for data clustering, it suffers to enable optimal classification with high dimensional data sets. Numerous optimizationefforts including genetic algorithm (GA) based clustering also require further optimization to avoid local minima issues. In this paper, an improved Canonical GA based Bisecting K-Means algorithm (CGABC) has been developed. The proposed model incorporates min-max normalization based feature normalization of the highdimensional data sets, which is followed by T-Test analysis that significantly reduces data dimensions based on feature similarity of the data elements. The fitness value has been assigned based on inter-cluster (heterogeneousdistance) and within-cluster (homogeneous distance) distances. To enable optimal features and process parameter selection, particularly cluster centers information, the conventional GA has been modified by applying multistage reproduction process, enhanced crossover and mutation. By incorporating the optimizedcluster center information the Bisecting K-Means clustering has been performed, which has exhibited optimal solution for highly accurate and efficient clustering with high dimensional data sets.

    • Planar liquid volume fraction and SMD distribution of Jatropha vegetable oil spray: effect of ethanol blending and GLR

      ANIKET P KULKARNI D DESHMUKH

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      This research paper presents the planar distribution of Sauter Mean Diameter (SMD) and liquid volume fraction in airblast sprays of Jatropha vegetable oil. The effect of ethanol blending at different gas to liquid mass ratios (GLRs) is presented. The planar SMD distributions are obtained using Structured Laser Illumination and Planar Imaging-Laser Sheet Drop sizing (SLIPI-LSD) and Particle/droplet Imaging Analysis (PDIA) techniques. The straight vegetable oil (SVO) spray showed poor atomization at GLR 1, which rose with increasing GLR. The blending of ethanol significantly improved the atomization of SVO even at GLR 1 condition. The liquid volume fraction distribution increased with higher GLR and with the increase in thepercentage of ethanol in the blend. The impact of the increase in ethanol on drop size is small at GLR of 5. The E30 blend showed uniformly distributed liquid in the spray plane with uniform SMD distribution in the range of 50 lm at GLR 5.

    • Cardiac events detection using curvelet transform

      ALKA BARHATTE MANISHA DALE RAJESH GHONGADE

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      Cardiac event detection is one of the essential steps in cardiac signal processing, analysis and disease diagnosis. Complete morphology of cardiac waves (P–QRS–T) extracted from the location of R-peak is helpful for feature extraction of many applications related to cardiac diseases classification. Therefore cardiacevent detection is a prerequisite for reliable cardiac disease diagnosis, and hence it should be robust and time efficient so that it can be used for real-time signal processing. This work proposes a novel method for R-peak detection using curvelet transform (CT). It demonstrates the use of curvelet energy with an adaptive threshold to estimate the boundaries around R-peak. The exact R-peak locations are then detected from the input signal with the predefined estimated boundaries. The proposed method is evaluated and analysed with all 48 records from the MIT-BIH arrhythmia database. The experimental analysis result yields an average sensitivity of 99.62%, average positive productivity of 99.74% and average detection error rate of 0.6%. The results obtained havehigher than or comparable indices to those in literature. Thus, the proposed system yields high accuracy, low complexity and high processing speed.

    • A sensitivity analysis of the design parameters for thermal comfort of thermally activated building system

      D G LEO SAMUEL S M SHIVA NAGENDRA M P MAIYA

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      Thermally activated building system (TABS) can be operated at relatively higher water temperature. Hence, it can be coupled with passive cooling systems. This paper investigates the influences of three design parameters on thermal comfort of TABS using COMSOL Multiphysics, a computational fluid dynamics(CFD) tool. For the same inlet velocity, an increase in the pipe inner diameter from 9 to 17 mm decreased the operative temperature (OT), a thermal comfort index, by 1.8°C. An increase in the pipe thermal conductivity from 0.14 to 1.4 W/mK reduced the average OT by 2.5°C. However, a further increase in thermal conductivity had no significant influence. For cooling pipes embedded at a constant depth, an increase in the thickness of both roof and floor from 0.1 to 0.2 m delayed and reduced the maximum OT by 48 minutes and 0.3°C, respectively.

    • Multifocus image fusion based on waveatom transform

      MEENU MANCHANDA DEEPAK GAMBHIR

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      Multifocus image fusion has emerged as a challenging research area due to the availability of various image-capturing devices. The optical lenses that are widely utilized in image-capturing devices have limited ‘depth-of-focus’ and, therefore, only the objects that lie within a particular depth remain ‘in-focus’, whereas all the other objects go ‘out-of-focus’. In order to obtain an image where all the objects are well focused, multifocus image fusion method based on waveatom transform is proposed. The core idea is to decompose all input images using waveatom transform and perform fusion of resultant waveatom coefficients. The waveatom coefficients with higher visibility, corresponding to sharper image intensities, are used to perform the process of image fusion. Finally, the fused image is obtained by performing inverse waveatom transform. The performance of the proposed method is demonstrated by performing fusion on different sets of multifocusimages and comparing the results of the proposed method to the results of existing image fusion methods.

    • Role of biocementation to improve mechanical properties of mortar

      SNIGDHA P BHUTANGE M V LATKAR T CHAKRABARTI

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      Biocementation or Microbially Induced Calcium Carbonate Precipitation (MICCP) is a naturally occurring green technique which involves the deposition of calcium carbonate by peculiar action of ureolytic bacteria, which improves the mechanical properties of cementitious materials. These bacteria require a proteinsource, a vitamin source and a carbon source for optimum growth. Urea and calcium source are necessary to carry out the ureolysis reaction to get CaCO₃ depositions which fill the voids within the cementitious materialsthereby improving their mechanical properties. To make the process economical, it is necessary to find out optimum concentrations of the various chemicals and ingredients used in the process. Present study aims at finding out the best possible combination of urea and protein source to carry out the MICCP process successfully. There was 22.44% increase in compressive strength and 16.62% reduction in the water absorption of experimental mortar cubes at 28 days of curing with the optimum combination of urea and protein sourceconcentrations.

    • Experimental investigation on mechanical properties of Al 7075/Al₂O₃/Mg NMMC’s by stir casting method

      S SURESH G HARINATH GOWD M L S DEVA KUMAR

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      There is an increasing demand for light-weight, affordable and rapidly processed products as a result of their significant level of superiority these days. In the present research, the effect of mechanical stir casting on 7075 based lightweight aluminium alloy established together with nano-Al₂O₃ with average particle size (20–30) nanometre and wt.% of (1.0, 2.0,3.0, and 4.0) has been studied. Several scientists exposed that nonconsistent of nanoparticles possessing high porosity in the matrix. Electric stir casting could protect against the difficulties encountered with mechanical stir casting. By infusing Al₂O₃ particulates right into aluminium alloy the aluminium 7075/1% Wt. Al₂O₃ is giving area to nanocomposite. By including 1%, micromagnesium powder improved the wettability of the reinforcement. Optical microscope, SEM, studies carried out for the evaluation of composites. SEM micrographs reported that the nanoparticles were consistently distributedthroughout the matrix and the active grain microstructure studies were preformed. The hardness, tensile strength, and impact results of Al7075/1% Wt. Al₂O₃ nanocomposites have been improved as compared with the Al7075 base alloy.

    • Notes on procedure for the development of fuzzy rules in SCOP methodology

      CHIDOZIE C NWOBI-OKOYE

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      The lack of statistical foundations among other shortcomings of existing methods of measuring efficiency necessitated the development of a new method called, Systems Coefficient of Performance Methodology (SCOPM). One key feature of SCOP methodology is the use of fuzzy logic to express complex efficiency measurement parameters into linguistic variables understandable by non experts and the general public. In this research note, the procedure for development of membership functions for the fuzzy logic aspect of SCOPM modeling was standardized and presented. A thorough analysis of fuzzy logic modeling which is at the heart of SCOPM was done. Real life examples and case studies are used to highlight the practical applications and utility of the methodology. The study gives a deep insight into the strengths of SCOP as an efficiency measurement method and its superiority over other efficiency measurement methods like, Data EnvelopmentAnalysis (DEA), Stochastic Frontier Analysis (SFA), etc. Finally, a guide to practitioners on implementation of SCOPM as well as future research direction for academics and researchers is presented.

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