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      Volume 44, Issue 9

      September 2019

    • Geotechnical stability assessment of a railway arch bridge more than 100-year old: a case study


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      In the present investigation, the geotechnical stability of the substructure of 100-year-old brick masonry rail bridges has been analysed numerically in the presence of nearby newly proposed concrete box bridges. Two different arch bridges (1273/1 and 1274/1) of Indian Railways (IR) have been considered in thisanalysis. Both bridges are made of brick masonry with different numbers of barrels. The numerical analysis has been performed using the finite-element (FE) method. The existing railway track between Kanpur and Jhansi, India, runs on these bridges, which were basically constructed by the British between 1888 and 1900. Therefore, the assessment of geotechnical safety and stability of such heritage bridges was of paramount importance from the IR point of view since the modern rail loading and other associated factors were changed significantly. Adetailed geotechnical investigation along with the plate load test was carried out at the respective bridge locations, and the results are reported in this paper. The distribution of the vertical stress and the settlement developed below the foundation of the bridges have been acquired from the FE investigation to judge the foundation safety against the strength and the serviceability perspective.

    • Unified and integrated authentication and key agreement scheme for e-governance system without verification table


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      E-governance or electronic governance is an application of Information and Communication Technology (ICT) for delivering cost-effective government services by any country to its citizens with reliability, transparency and efficiency. Majority of authentication schemes for e-governance in India are based on single-server environment. To access the services, users need to register themselves at the authentication server for every e-governance service. Various e-governance services work through different servers, and therefore users get registered on each server separately. These services and servers require a unified and integratedauthentication scheme to overcome the problem of multiple registrations and login processes. This paper proposes a dynamic authentication protocol based on the identity of a user for multi-server architecture without using verification tables. It is also capable of integrating all the existing e-governance projects. The proposedprotocol fulfills the security requirements such as mutual authentication, traceability and identity protection along with the facility to share a session key among all the servers for secure communication.

    • Effect of part sweep on axial flow compressor performance in the presence of circumferential casing grooves


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      Modern axial compressors demand high performance and increased operating range. High performance is generally obtained by employing 3D design features, such as sweep and lean. To improve operating range, use of circumferential casing grooves is quite common. An extensive numerical study is carried out tounderstand performance change due to swept rotor blade on axial compressor performance and stall margin, in the presence of circumferential casing grooves. Numerical methodology used in the current work is validated with experimental data of NASA Rotor37. Grid sensitivity as well as turbulence model validation is carried out to validate numerical methodology used in this work. A baseline rotor is created without any sweep. Sweep considered in this study is employed only at part span of the blade. Impact of part sweep with circumferentialcasing grooves is not reported by many in open literature, which is the focus of this work. Different magnitudes of sweep are considered in this study. The current study indicates existence of an optimum combination of magnitude of sweep and span location at which sweep starts from. Sweep in the presence of circumferentialgrooves results in considerable increase of operating range with nominal decrease in efficiency. A detailed flow field investigation is presented to understand the underlying flow physics.

    • Solidification cracking susceptibility of ferritic stainless steels using Modified Varestraint Transvarestraint (MVT) method


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      The Modified Varestraint Transvarestraint (MVT) test was used to investigate the solidification cracking susceptibility of an unstabilised, a Nb-stabilised and two (Ti + Nb) dual-stabilised ferritic stainless steels. Two different welding speeds of 6 and 3 mm/s using autogenous gas tungsten arc welding were employed. At the welding speed of 6 mm/s, the high-content (Ti + Nb) steel was resistant and the Nb-stabilised steel was marginally susceptible to solidification cracking. At the welding speed of 3 mm/s, the Nb and the high (Ti + Nb) steels were found to be marginally susceptible to solidification cracking while the unstabilised andlow-content (Ti + Nb) grades were resistant to solidification cracking. The weld metal microstructures transverse to the welding direction revealed columnar grains in all the samples for both welding speeds. The ferritic stainless steels were generally resistant to solidification cracking, except the Nb-stabilised steel, which was marginally susceptible to solidification cracking.

    • Methane–air-premixed flames impinging on plane surfaces


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      Determination of heat transfer characteristic has been analysed theoretically using the heat propagation phenomena of methane–air-premixed turbulent flames impinging on plane surfaces. The heat flux propagation on the plane surface completely depends on the distance between the plate and nozzle, Reynoldsnumber and equivalence ratio (ER). The solution of the differential equation related to conservation of momentum, mass and energy has been analysed. The radiative heat transfer model has been designed using several radiation models and the turbulence model is analysed by the help of RNG κ–ε turbulence model. In the response plot it is found that heat flux increases progressively with the radial distance towards the centre of the plate to achieve the maximum value at a position a bit away from stagnation point and thereafter it reduces. It has also been exhibited that when the distance of the target plate increases, the location of the maximum value of the local heat flux approaches the stagnation point. The dependence of heat transfer phenomena on ER, Reynolds number and separation of the plate from the nozzle has been studied.

    • Experimental investigation of surface integrity after wire electro-discharge machining of Ti–6Al–4V


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      This article presents the relationship of machining parameters containing pulse-on time (Ton), pulse off time (Toff), peak current (IP) and servo voltage (SV) on surface integrity characteristics, including white layer thickness (WLT), heat-affected zone (HAZ) and surface crack density (SCD) and also on material removal rate (MRR), after wire electric discharge machining of Ti–6Al–4V. Taguchi’s method was utilized to design the experiments, and response surface methodology (RSM) was employed for developing the empirical models.Results indicated that Ton and IP played a significant role on surface integrity characteristics. In addition, the microstructure of selected machined samples was analysed using a field emission scanning electron microscope (FESEM) and energy-dispersive X-ray (EDX) analysis. Accuracy of models was examined using residual analysis and confirmation runs. Finally, multi-response optimization of process parameters was obtained using desirability approach. Results can be used to improve the quality of the machined work piece significantly to fulfil the requirements of the various industries. The novelty of this research is mainly investigation and multi-response optimization of all the surface integrity characteristics at the same time.

    • Design of a high speed Vedic multiplier and square architecture based on Yavadunam Sutra


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      In current day situation we come across numerous mathematical challenges. This could be overwhelmed by the Vedic Mathematics. Vedic Mathematics is an ancient approach to solve problems in a rapid manner. In this paper the design of a novel Vedic square and multiplier architecture based on Yavadunam Sutra is proposed. Yavadunam is a squaring sutra of the Vedic Mathematics. We have designed a generic architecture for this squaring sutra and have designed a high speed Vedic binary multiplier architecture using the principles of Yavadunam sutra. The proposed multiplier offers significant improvement in speed. Xilinx Spartan FPGA is used to design and realize the architecture and the Synopsys device with 90 nm and 180 nm technology is used to synthesize the same.

    • Terminal adaptive control for a class of uncertain underactuated systems


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      This paper presents a backstepping-based terminal adaptive control solution for a class of uncertain underactuated systems with two degrees of freedom. The control scheme developed in this work is based on the finite time stability approach for the terminal convergence of system outputs. Due to the physical restrictionsassociated with underactuated systems, classical backstepping approach is not applicable to this class of nonlinear systems and hence an approximate version is developed by designing a suitable error surface. Control term is developed in two steps: first, non-singular pseudo-control terms are developed for the dimensions of the configuration space and thereafter a feasible control term is designed to ensure the finite time convergence of error surface. The error surface is designed such that its finite time convergence in turn implies the terminal convergence of configuration variables. To ensure a well-defined control term over the entire state space, control components are embedded with corrective terms. Corrective terms are designed so as to avoid the singularity of the control term and to preserve the desired controller response up to certain extent. A fuzzy logic system is usedfor the approximation of unknown systems dynamics. Simulation results demonstrate the effectiveness of the control approach.

    • LMI-based robust tracking of a class of MIMO nonlinear systems


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      Reference tracking problem for MIMO Lipschitz nonlinear systems is examined here. Presently a vast literature exists on observer design of unforced systems containing Lipschitz nonlinearities. However, these existing results cannot be readily extended for controller design containing reference tracking ability. Here aLinear State Variable Feedback (LSVF) controller is designed for MIMO Lipschitz nonlinear systems with norm-bounded parametric uncertainties using the concept of input to state stability Lyapunov functions. The whole problem is cast into a framework of Linear Matrix Inequalities, to exploit its numerical capabilities.Analytical proofs are supplemented with simulation examples, which show certain advantages over existing results. Apart from state feedback, observer-based output feedback is also considered for controller design.

    • ReLiC: entity profiling using random forest and trustworthiness of a source


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      The digital revolution has brought most of the data in the world to the world wide web, but at the same time, the data available on WWW has increased manyfold in the past decade. Social networks, online clubs etc., have come into existence. Expert systems are required to extract information from these venues about areal-world entity like a person, organisation, event, etc. However, this information may change over time, and there is a need to maintain the data. Therefore, it is desirable to have an intelligent model to extract relevant data items from different sources and merge them to build a complete profile of an entity (entity profiling). Further, this model should be able to handle incorrect or obsolete data items. In this paper, we propose a novel method for completing a profile. We have developed a two-phase method. (1) The first phase (resolution phase) linksrecords to the queries. We have studied the performance of various classifiers for this purpose and observed that the use of the random forest is best suited for entity resolution. Also, we proposed and used ‘‘trustworthiness of a source’’ as a feature to the random forest. (2) The second phase selects the appropriate values from records to complete a profile based on our proposed selection criteria. We used the concept of assigning authority to a reliable source in entity profiling, and it is established through our results that the use of an authoritative sourcehas significantly improved the performance of the proposed system. Experimental results show that our proposed system ReLiC outperforms COMET.

    • Provisioning in transport networks using power-aware resource allocation algorithms


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      Transport technologies such as Optical Transport Network and Synchronous Digital Hierarchy are widely used in access and core networks to carry different types of traffic. These technologies define a hierarchy for multiplexing lower rate traffic containers onto higher rate traffic containers. Provisioning refers to the process of allocation of resources to meet a given traffic demand. Due to the continued expansion of transport networks, the power consumption increases, becoming a bottleneck for further expansion. Power-aware allocation ofresources to traffic demands will enable power-efficient operation and help in minimizing the capital and operational costs of the network. In this paper, the power consumed by a switch matrix having the capability to switch different traffic containers at different amounts is considered. The objective is to minimize the number of network elements deployed in the network by allocating resources to traffic demands in power-efficient ways. A formulation based on Integer Linear Programming is first presented; later, four different heuristic approaches,based on how higher order trails are used and the use of grooming, are proposed. It is found that the grooming based heuristics perform better in terms of the total power consumption relative to the weighted number of requests accepted. In the grooming heuristics, threshold on link utilization is set to determine when grooming is to be done, and for the same performance evaluation, it is found that the threshold of 80% gives better results.

    • Photocatalytic degradation in silver doped TiO₂


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      Many intriguing ways have been identified to mitigate the low photocatalytic activity of Titanium dioxide (TiO ₂). One of the ways is to adulterate the structure of TiO ₂ with foreign substances like metals i.e., Ni ²⁺, Zn ²⁺ Cr ³⁺ and Fe ³⁺, which are having similar radii with Ti ⁴⁺ In this study, the introduction of silver into the structure of TiO ₂ by Liquid Impregnation (LI) method with various mole fractions have been presented. Comparison has been made to degrade one model pollutant: Direct Blue 71 (DB71) by using both doped and undoped TiO ₂. Study was further supported by studying the Langmuir and Freundlich isotherms. Enhancement in the photocatalytic degradation of the dye was observed with silver doped TiO ₂ at 2.0% mole fraction as compared to undoped TiO ₂. While studying the photoctalytic activity, the reaction mixture pH was kept unchanged with doped TiO ₂, wherein with undoped TiO ₂ demanded acidic pH to have more photocatalytic activity.

    • Capacited P-hub location problem allowing direct flow between spokes in intermodal transportation network


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      For the last twenty five years, hub location problems have become an important research area in the Location Theory. The use of hub and spoke network structure in modern transportation and telecommunication systems has a great effect on this. In hub and spoke systems flows from sources are collected in the hubs, whichare generally located centrally and serve as collection and distribution points, and distributed to the destinations again via hubs to use advantages of the economies of scale. In this study, real-life problem of a Turkish public institution is addressed. Different from the studies in the literature, we consider an intermodal transportationnetwork where spoke-to-hub and hub-to-spoke transportation could be either land or air movement while hub-to hub transportation is only air movement. The proposed study differs in some respects from studies in the literature. Firstly, obligation to use of hubs for the flows between origin and destination pairs is relaxed. Secondly, due to the special nature of the problem being addressed not all the nodes are considered to be candidates as hubs, instead some specific nodes are taken into consideration. Lastly, hubs’ capacities are made to be affected by the flow not only from hubs but also spokes. The results showed that the proposed model produced a lower total cost compared to the studies in the literature and the current applied method.

    • BREAK, MAKE and TAKE: an information retrieval approach


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      Ranking functions used in information retrieval are primarily used in the search engines and they are often adopted for various language processing applications. This paper introduces some novel heuristics combined with probabilistic retrieval functions and are employed in the domain of approximate string similarityproblem. Various algorithms have been proposed in the literature to solve approximate string similarity problems; however, none of them makes use of probabilistic retrieval functions. We are the first to explore the intersection between these two areas, that is between string similarity and information retrieval, and propose heuristic designs to resolve this problem. First, we propose chunking heuristic function, called BREAK. We show the variants BREAK-1, -2, -OFF, which split up the terms with the sequential notion. Then we propose BREAK-n, which generalizes these variants and scales to larger datasets. In order to relate these split-ups, we propose a graphical error modelling heuristics MAKE over the BREAK variants. Finally, we propose TAKE curve, a novel feature engineering probabilistic distribution, which replaces the prevalent normalizationheuristics. Taking the advantage of flexibility over the choice of heuristics, we assess the variants on the cognate detection, mutant identification and problems based on isolated spelling correction. In the extensive evaluationmethods, we found that our designs perform better than prevalent heuristics and are robust against database characteristics.

    • Influence maximization in online social network using different centrality measures as seed node of information propagation


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      Information propagation in the network is probabilistic in nature; simultaneously, it depends on the connecting paths of the propagation. Selection of seed nodes plays an important role in determining the levels and depth of the contagion in the network. This paper presents a comparative study when seed nodes forinformation propagation are selected through the properties of different centrality measures in the social network. This study captures the interaction measures of nodes in the social network, selects seed nodes based on five centrality measures, i.e. degree distribution, betweenness centrality, closeness centrality, Eigenvector and PageRank, and compares the affected nodes and levels of propagation within the network. We demonstrate the performance of the different centrality measures by processing three datasets of social network: Twitter network, Bitcoin network and author collaborative network. For the propagation of the information, we use breadth-first search (BFS) and susceptible–infectious–recovered (SIR) model and a detailed comparative study is also presented for each of the seed nodes selected using aforementioned network properties. Results show that the Eigenvector centrality and PageRank centrality measures outperform other centrality measures in all test cases in terms of propagation level and affected nodes during information propagation. Both Eigenvector and PageRank network data processing required a high computational overhead. For this reason we propose a hybrid model where using k-core the network is degenerated into a smaller network and centrality nodes are extracted from the smaller network. These centrality nodes, as compared to original centrality nodes, perform almost in the same manner in terms of influence maximization when k is chosen in a rational way.

    • Optimization of imperfect economic manufacturing models with a power demand rate dependent production rate


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      The constant demand rate is the most common assumption of the basic economic production quantity model, which is not very frequent in practice. In real world situations, demand usually varies with time. With regard to the widespread necessity of power demand pattern, demand is supposed to follow a power law.Another unrealistic assumption is perfect quality of all items. This paper presents a production system with defective items to determine the optimal replenishment quantity, cycle length and backordered size with a power demand rate dependent production rate. We assume that a manufacturer may be faced with three different cases regarding to the date that defective items are drawn from inventory. The set-up, backordering, inspection, and production costs, as well as holding cost of both perfect and imperfect items are accounted in the inventory system. An algorithm is offered to optimize total inventory cost and then numerical analyses are presented to demonstrate the applicability of the proposed models. Finally, some sensitivity analyses and managerial insights are provided.

    • Feasibility study of installation of MW level grid connected solar photovoltaic power plant for northeastern region of India


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      Solar energy is one of the most suitable renewable energy options in India. In the last decade, solar energy installations have received an ample impetus in India due to active initiatives taken by the Indian government. However, the solar energy potential of country’s North-Eastern (NE) part is not utilized effectivelyso far. In the present study, a comprehensive analysis of the feasibility of installation of a megawatt-level grid connected solar photovoltaic (SPV) power plant in all the state capitals of NE India is carried out. The climatic data collected from various online sources and NASA climatic database were utilized in designing a 2 MW SPV plant. The theoretical procedure involved in designing the SPV plant is also presented in this study. PVsyst simulation software is used to predict the performance of 2 MW power plants for these eight states of India. From the analysis, it is observed that NE India has an immense potential for installation of solar energy conversion devices and thus it can be harvested economically. It has been observed that locations of Guwahati and Gangtok provide a high performance ratio of 0.855. Aizawl provides the minimum unit cost of electricitygenerated at a value of 3.88 INR/unit. The analysis also reveals that the Aizawl and Guwahati are the most suitable locations for installation of SPV power plant amongst the NE capitals.

    • Design and analysis of a novel permanent magnet synchronous machine with axial assisted magnets


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      The paper proposes a novel permanent magnet synchronous machine (NPMSM) with one radial permanent magnet synchronous machine (RPMSM) in the center and two axial permanent magnet synchronous machines (APMSMs) on both sides. The two APMSMs take advantage of the stator end winding spaces of theRPMSM and provide additional output power without increasing the whole machine volume. The emphasis of this study is on the unique rotor structure design and its merits for producing additional output power. The 3Dfinite element method (FEM), coupling with the equivalent circuit method is used in the study for designing the NPMSM. And the NPMSM prototype test results match well with the calculated results.

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