• Gaurav

      Articles written in Sadhana

    • Traffic planning for non-homogeneous traffic

      Geetam Tiwari Joseph Fazio Sushant Gaurav

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      Traffic on Indian roads (both urban and inter-urban) consists of a variety of vehicles. These vehicles have widely different static and dynamic characteristics. The traffic is also very different from homogeneous traffic which primarily consists of motorized vehicles. Homogeneous traffic follows strict lane discipline as compared to non-homogeneous traffic. Western traffic planning methodologies mostly address the concerns of homogeneous traffic and therefore often prove inadequate in solving problems involving non-homogeneous traffic conditions as found in Indian cities. This paper presents studies conducted on non-homogeneous traffic. Section 1 presents a methodology to verify the continuity equation, the basic block of any traffic planning analysis. In § 2, the methodology developed is applied to modify the Highway Capacity Manual (HCM) 2000 density method to derive passengercar equivalencies (PCEs) or units (PCUs) for heavy vehicles and recreational vehicles. These PCUs appear as ‘ET’ and ‘ER’ in HCM tables. The density method assumes motorized, four-wheeler traffic, i.e., homogeneous traffic, and does not include motorized three-wheelers, motorized two-wheelers, and non-motorized traffic often present on Indian highways. By modifying the density method to represent non-homogeneous traffic, which includes significant percentages of motorized, three-wheelers, motorized two-wheelers, and non-motorized traffic entities, one can derive more accurate passenger car units for Indian conditions. Transport professionals can use these PCU values for accurate capacity, safety, and operational analysis of highways carrying non-homogeneous traffic.

    • Wavelet packet transform-based robust video watermarking technique

      Gaurav Bhatnagar Balasubrmanian Raman

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      In this paper, a wavelet packet transform (WPT)-based robust video watermarking algorithm is proposed. A visible meaningful binary image is used as the watermark. First, sequent frames are extracted from the video clip. Then, WPT is applied on each frame and from each orientation one sub-band is selected based on block mean intensity value called robust sub-band. Watermark is embedded in the robust sub-bands based on the relationship between wavelet packet coefficient and its 8-neighbour $(D_8)$ coefficients considering the robustness and invisibility. Experimental results and comparison with existing algorithms show the robustness and the better performance of the proposed algorithm.

    • A survey on optical character recognition for Bangla and Devanagari scripts

      Soumen Bag Gaurav Harit

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      The past few decades have witnessed an intensive research on optical character recognition (OCR) for Roman, Chinese, and Japanese scripts. A lot of work has been also reported on OCR efforts for various Indian scripts, like Devanagari, Bangla, Oriya, Tamil, Telugu, Malayalam, Kannada, Gurmukhi, Gujarati, etc. In this paper, we present a review of OCR work on Indian scripts, mainly on Bangla and Devanagari—the two most popular scripts in India. We have summarized most of the published papers on this topic and have also analysed the various methodologies and their reported results. Future directions of research in OCR for Indian scripts have been also given.

    • Manipulation of interfacial instabilities by using a soft, deformable solid layer

      Gaurav V Shankar

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      Multilayer flows are oftensusceptible to interfacial instabilities caused due to jump in viscosity/elasticity across thefluid–fluid interface. It is frequently required to manipulate and control these interfacial instabilities in various applications such as coating processes or polymer coextrusion. We demonstrate here the possibility of using a deformable solid coating to control such interfacial instabilities for various flow configurations and for different fluid rheological behaviors. In particular, we show complete suppression of interfacial flow instabilities by making the walls sufficiently deformable when the configuration was otherwise unstable for the case of flow past a rigid surface. While these interfacial instabilities could be suppressed in certain parameter regimes, it is also possible to enhance the flow instabilities by tuning the shear modulus of the deformable solid coating for other ranges of parameters.

    • Parameter estimation of linear and quadratic chirps by employing the fractional fourier transform and a generalized time frequency transform

      Shishir B Sahay T Meghasyam Rahul K Roy Gaurav Pooniwala Sasank Chilamkurthy Vikram Gadre

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      This paper is targeted towards a general readership in signal processing. It intends to provide a brief tutorial exposure to the Fractional Fourier Transform, followed by a report on experiments performed by the authors on a Generalized Time Frequency Transform (GTFT) proposed by them in an earlier paper. The paper also discusses the extension of the uncertainty principle to the GTFT. This paper discusses some analytical results of the GTFT. We identify the eigenfunctions and eigenvalues of the GTFT. The time shift property of the GTFT is discussed. The paper describes methods for estimation of parameters of individual chirp signals on receipt of a noisy mixture of chirps. A priori knowledge of the nature of chirp signals in the mixture – linear or quadratic is required, as the two proposed methods fall in the category of model-dependent methods for chirp parameter estimation.

    • Experimental and numerical analysis for optimal design parameters of a falling film evaporator

      RAJNEESH KAUSHAL RAJ KUMAR GAURAV VATS

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      Present study exhibits an experimental examination of mass transfer coefficient and evaporative effectiveness of a falling film evaporator. Further, a statistical replica is extended in order to have optimal controlling parameters viz. non-dimensional enthalpy potential, film Reynolds number of cooling water, Reynolds number of air and relative humidity of up-streaming air. The models not only give an optimal solution but also help in establishing a correlation among controlling parameters. In this context, response surface methodology is employed by aid of design of experiment approach. Later, the response surface curves are studied using ANOVA. Finally, the relations established are confirmed experimentally to validate the models. The relations thus established are beneficent in furtherance of designing evaporators. Additionally, the presentstudy is among the first attempts to reveal the effect of humidity on the performance of falling film evaporator.

    • Identifying factors causing cost overrun of the construction projects in India

      SWAPNIL P WANJARI GAURAV DOBARIYA

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      Delay and cost overrun are common phenomena in projects worldwide. However, these are especially severe in developing countries. In India as per MOSPI report, 235 projects out of 410 were severely affected cost overrun due to certain factors. A short questionnaire was conducted with 15 prominent factorsresponsible for cost overrun and forwarded to 190 constructional professionals across India. Total 85 responses were received and it was analyzed using various statistical tools such as analysis of variance (ANOVA) and factor analysis tool using SPSS. In this study, top three factors affecting cost overruns were identified such as price escalation of raw material, delay in planned activity and lack of co-ordination between construction parties which could be significantly responsible for cost overnun of construction project in India. Factor analysismethod was also carried out to group the factors into three components of overall questionnaire. These components, such as client control component, project management component, and contractor control component,would be useful to the various parties involved in the construction activities. This paper also provides suggestive frameworks which have been framed after discussing with large number of construction professionals or expert

    • A study of energy transfer during water entry of solids using incompressible SPH simulations

      PRAPANCH NAIR GAURAV TOMAR

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      Cavity formation during water entry of a solid corresponds to the deceleration experienced by the solid. Several experimental studies in the past have facilitated qualitative understanding of the relation between flow and impact properties and the type of cavity formed. The types of cavities formed are classified primarilybased on the nature of the seal, such as (a) surface seal, (b) deep seal, (c) shallow seal and (d) quasi-static seal. The flow mechanism behind these features and their effects on the speed of the impacting solid require further quantitative understanding. A study of such phenomenon is difficult using the existing CFD techniques owing to the fact that the high density ratios between the two phases, namely water and air, bring in issues with respect to the convergence of the linear system used to solve for the pressure field for a divergence-free velocity field.Based on a free surface modeling method, we present Incompressible Smoothed Particle Hydrodynamics (ISPH) simulations of water entry of two-dimensional solids of different shapes, densities and initial angular momenta.From the velocity field of the fluid and shape of the cavity, we relate the transfer of kinetic energy from the solid to the fluid through different phases of the cavity formation. Finally, we present a three-dimensional simulation of water entry to assert the utility of the method for analysis of real life water entry scenarios.

    • Experimental and numerical analysis for optimal design parameters of a falling film evaporator

      RAJNEESH KAUSHAL RAJ KUMAR GAURAV VATS

      More Details Abstract Fulltext PDF

      Present study exhibits an experimental examination of mass transfer coefficient and evaporative effectiveness of a falling film evaporator. Further, a statistical replica is extended in order to have optimal controlling parameters viz. non-dimensional enthalpy potential, film Reynolds number of cooling water, Reynolds number of air and relative humidity of up-streaming air. The models not only give an optimal solution but also help in establishing a correlation among controlling parameters. In this context, response surface methodology is employed by aid of design of experiment approach. Later, the response surface curves are studied using ANOVA. Finally, the relations established are confirmed experimentally to validate the models. The relations thus established are beneficent in furtherance of designing evaporators. Additionally, the presentstudy is among the first attempts to reveal the effect of humidity on the performance of falling film evaporator.

    • Identifying factors causing cost overrun of the construction projects in India

      SWAPNIL P WANJARI GAURAV DOBARIYA

      More Details Abstract Fulltext PDF

      Delay and cost overrun are common phenomena in projects worldwide. However, these are especially severe in developing countries. In India as per MOSPI report, 235 projects out of 410 were severely affected cost overrun due to certain factors. A short questionnaire was conducted with 15 prominent factorsresponsible for cost overrun and forwarded to 190 constructional professionals across India. Total 85 responses were received and it was analyzed using various statistical tools such as analysis of variance (ANOVA) and factor analysis tool using SPSS. In this study, top three factors affecting cost overruns were identified such as price escalation of raw material, delay in planned activity and lack of co-ordination between construction parties which could be significantly responsible for cost overnun of construction project in India. Factor analysismethod was also carried out to group the factors into three components of overall questionnaire. These components, such as client control component, project management component, and contractor control component,would be useful to the various parties involved in the construction activities. This paper also provides suggestive frameworks which have been framed after discussing with large number of construction professionals or expert

    • Provably secure group key management scheme based on proxy re-encryption with constant public bulletin size and key derivation time

      GAURAV PAREEK B R PURUSHOTHAMA

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      Users share a group key to decrypt encryptions for the group using a group key management scheme. In this paper, we propose a re-encryption-based group key management scheme, which uses a unidirectional proxy re-encryption scheme with special properties to enable group members share the updated groupkey with minimum storage and computation overhead. In particular, we propose a proxy re-encryption scheme that supports direct re-encryption key derivation using intermediate re-encryption keys. Unlike multihop re-encryption, the proposed proxy re-encryption scheme does not involve repeated re-encryption of themessage. All the computations are done on the re-encryption key level and only one re-encryption is sufficient for making the group key available to the users. The proposed scheme is the first for group key management based on proxy re-encryption that is secure against collusion. The individual users store just one individual secret key with group key derivation requiring OðlogNÞ computation steps for a group of N users. Size of the public bulletin maintained to facilitate access to the most recent group key for off-line members is O(N) andremains constant with respect to the number of group updates. The proposed group key management scheme confronts attacks by a non-member and even a collusion attack under standard cryptographic assumptions.

    • Estimation of azimuth of a macro cell through user data for LTE access network

      BRIJESH SHAH GAURAV DALWADI RAHUL BHASKER HARDIP SHAH NIKHIL KOTHARI

      More Details Abstract Fulltext PDF

      The number of antennas on a site increases due to a simultaneous deployment of multi-band and multi-mode radios to combat extremely growing data demand in the network. The correct values of physical parameters of antennas, including azimuth, height and tilt, are essential to optimize the radio frequency (RF)network automatically. It is seen that poor results in RF network optimization are mainly due to incorrect azimuth. The proposed algorithm can estimate the azimuth of an antenna in the field using passive monitoring data from the user equipment. It has been developed to identify the correct value of azimuth without doing thefield audit, which can significantly reduce the time for optimization and operational expenditure (OPEX) as well. The field trial reveals that the estimated azimuth value closely matches within ±12° range in comparison to theactual value in the field. Moreover, field results show that the same algorithm is equally applicable for urban and rural morphologies as well. It can also be automated to sanctify the physical site database with proper azimuthvalues at large level without introducing any kind of human error.

    • Dynamic model of fractional thermoelasticity due to ramp-type heating with two relaxation times

      GAURAV MITTAL VINAYAK S KULKARNI

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      This is an attempt to design a fractional heat conduction model in a bounded cylindrical region exposed to axisymmetric ramp-type heat flux and discuss its thermal behaviour. This model is drafted using the classical theory of fractional thermoelasticity due to the involvement of two relaxation times to the heatconduction equation and the equations of motion. In order to achieve finite thermal wave speed, the heat conduction equation is derived from the viewpoint of Maxwell–Cattaneo law in the context of fractional derivative. Analytical results for the distribution of temperature, displacement and thermal stresses are obtainedusing integral transforms in the Laplace domain. The Gaver–Stehfest method has been used to invert the results of Laplace domain. The convergence of infinite series solutions has been discussed. As a specific case this model has been applied to a thick circular plate subjected to the axisymmetric ramp-type heat flux. The results obtained for the thermal variations are validated by comparing to coupled and generalized theory of thermoelasticity. These comparisons are shown graphically.

    • Extended hierarchical key assignment scheme (E-HKAS): how to efficiently enforce explicit policy exceptions in dynamic hierarchies

      GAURAV PAREEK B R PURUSHOTHAMA

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      In this paper, we focus on practically motivated flexibility requirements for the hierarchical access control model, namely transitive exception and anti-symmetric exception. Additionally, we motivate a new flexibility requirement called ‘‘class delegation with descendant(s) safety’’ in a practical application scenario.We propose our extended hierarchical key assignment scheme (E-HKAS) that satisfies all three aforementioned flexibility requirements in a dynamic hierarchy of security classes. To propose a generic E-HKAS, we model the hierarchical access control policy as a collection of access groups. E-HKAS enforces transitive and antisymmetric exceptions using an efficient group-based encryption scheme. To enforce class delegation with descendant(s) safety, we propose a novel cryptographic primitive called group proxy re-encryption (GPRE) thatsupports proxy re-encryption between two access groups. We present an IND-CPA-secure construction of our proposed GPRE scheme and formally prove its security. Performance analysis shows that the proposed E-HKASenforces explicit transitive and anti-symmetric exceptions more efficiently than the existing approaches in the literature. Computation cost for key derivation is constant and does not depend on the depth of the hierarchy. Also, to enforce class delegation with descendant(s) safety, the proposed E-HKAS requires constant number of computational steps to be executed.

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