Browsing by Author "Nayak S."

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An approach of fuzzy and TOPSIS to bi-level multi-objective nonlinear fractional programming problem
(2019) Nayak S.; Ojha A.
This paper proposes a solution technique to bi-level multi-objective nonlinear fractional programming problem which is based on the concept of TOPSIS (technique for order preference by similarity to ideal solution) and fuzzy goal programming approach. Nonlinear polynomial functions are considered as the numerators as well as denominators of the fractional objectives at each level. The concept used implements simultaneous minimization and maximization of the functions (numerators and denominators of fractional objectives, decision variables controlled by the upper level decision makers) from their respective aspired (ideal) and acceptable (anti-ideal) values. Distance functions and their corresponding fuzzy membership functions are constructed at both levels for the objectives. Aspired and acceptable values of the decision variables of upper level are ascertained using a certain process. The sum of only under deviational variables obtained from the fuzzy membership goals of the distance functions and the decision variables controlled by upper level decision maker is minimized to obtain the best compromise solution of the concerned bi-level problem. Some comparative discussions with an existing approach are incorporated, and two illustrative numerical examples are discussed to demonstrate the effectiveness of the proposed method. � 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
An approach to solve multi-objective linear fractional programming problem
(2016) Nayak S.; Ojha A.K.
In this paper, an approach of hybrid technique is presented to derive Pareto optimal solutions of a multi-objective linear fractional programming problem (MOLFPP). Taylor series approximation along with the use of a hybrid technique comprising both weighting and ?-constraint method is applied to solve the MOLFPP. It maintains both priority and achievement of possible aspired values of the objectives by the decision maker (DM) while producing Pareto optimal solutions. An illustrative numerical example is discussed to demonstrate the proposed method and to justify the effectiveness, the results so obtained are compared with existing fuzzy max�min operator method. � Springer Science+Business Media Singapore 2016.
Assessing tsunami vulnerability of structures designed for seismic loading
(2014) Nayak S.; Reddy M.H.O.; Madhavi R.; Dutta S.C.
Wave movement with large velocity triggered by strong earthquake occurring at the sea bed is generally the primary cause of the tsunami. Occurrence of tsunami (like the one during the Sumatra earthquake in 2004 or the one during the Tohoku earthquake in Japan in 2011) causes devastating damages to the coastal structures and tremendous casualties. Seismic resistant design procedure is more popularly followed in various countries as per the relevant seismic codes. It is the need of the hour to see whether the lateral load-resisting capability attributed through seismic design is sufficient to resist tsunami loading. The present study using available design guidelines in various seismic codes and well accepted design literature for tsunami loading attempts to achieve this end in a limited form. The study may be helpful in providing a broad overview of tsunami vulnerability of coastal structures which are designed following the mandatory requirements of seismic codes. Such tsunami vulnerability is attempted to be recognized in terms of critical height that corresponds to maximum inundation depth of tsunami wave which the structure may withstand because of being aseismically designed. Thus, the results presented in this study may prove useful in assessing and reducing tsunami vulnerability of coastal structures. � 2013 Elsevier Ltd.
A critical review of retrofitting methods for unreinforced masonry structures
(2014) Bhattacharya S.; Nayak S.; Dutta S.C.
Unreinforced masonry (URM) buildings are common throughout Latin America, the Himalayan region, Eastern Europe, Indian subcontinent and other parts of Asia. It has been observed that these buildings cannot withstand the lateral loads imposed by an earthquake and often fails, in a brittle manner. Methods for retrofitting URM buildings to increase the time required for collapse and also to improve the overall strength widely vary. This review has collated information on various types of retrofitting methods either under research or early implementation. Furthermore, these methods are categorized and critically analyzed to help further understand which methods are most suitable for future research or application in developing countries. The comparison of the different methods is based on economy, sustainability and buildability and provides a useful insight. The study may provide useful guidance to policy makers, planners, designers, architects and engineers in choosing a suitable retrofitting methodology. � 2013.
Electron Transfer Directed Antibacterial Properties of Graphene Oxide on Metals
(2018) Panda S.; Rout T.K.; Prusty A.D.; Ajayan P.M.; Nayak S.
Nanomaterials such as silver nanoparticles and graphene-based composites are known to exhibit biocidal activities. However, interactions with surrounding medium or supporting substrates can significantly influence this activity. Here, it is shown that superior antimicrobial properties of natural shellac-derived graphene oxide (GO) coatings is obtained on metallic films, such as Zn, Ni, Sn, and steel. It is also found that such activities are directly correlated to the electrical conductivity of the GO-metal systems; the higher the conductivity the better is the antibacterial activity. GO-metal substrate interactions serve as an efficient electron sink for the bacterial respiratory pathway, where electrons modify oxygen containing functional groups on GO surfaces to generate reactive oxygen species (ROS). A concerted effect of nonoxidative electron transfer mechanism and consequent ROS mediated oxidative stress to the bacteria result in an enhanced antimicrobial action of naturally derived GO-metal films. The lack of germicidal effect in exposed cells for GO supported on electrically nonconductive substrates such as glass corroborates the above hypothesis. The results can lead to new GO coated antibacterial metal surfaces important for environmental and biomedical applications. � 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Empirical mode decomposition and Hessian LLE in Fluorescence spectral signal analysis for Cervical cancer detection
(2025) Deo B.S.; Nayak S.; Pal M.; Panigrahi P.K.; Pradhan A.
Cervical cancer is a significant cause of female mortality worldwide. The timely and accurate identification of different stages of cervical cancer has the capacity to significantly improve both treatment efficacy and patient survival duration. Fluorescence spectroscopy acts as a significantly sensitive technique for identifying the biochemical changes that occur during the advancement of cancer. Fluorescence spectral data was collected from a diverse set of 110 human cervix samples in our study. The spectral data underwent an initial preprocessing step that included data normalization. Subsequently, empirical mode decomposition (EMD) was utilized to decompose the signal into several intrinsic mode functions within the spectral domain. Thereafter, various nonlinear dimensionality reduction methods, including Isomap, Local Linear Embedding (LLE), and Hessian LLE, were applied to extract more informative features in a lower-dimensional representation. Furthermore, a 1D convolutional neural network (CNN) was employed to categorize the lower dimensional spectral signals into three classes: normal, pre-cancerous, and cancerous. The proposed methodology attained the best evaluation metrics using the Hessian LLE dimensionality reduction technique. A mean classification accuracy, precision, recall, F1-score, and specificity of 98.72%, 98.02%, 98.61%, 98.00%, and 99.30%, respectively, were obtained through a 5-fold cross-validation technique. The combination of fluorescence spectroscopy and machine learning holds promise for detecting cancer at earlier stages than current diagnostic methods. � 2024 Elsevier Ltd
Generating Pareto Optimal Solutions of Multi-Objective LFPP with Interval Coefficients Using ?-Constraint Method
(2015) Nayak S.; Ojha A.
Abstract: This paper illustrates a procedure to generate pareto optimal solutions of multi-objective linear fractional programming problem (MOLFPP) with closed interval coefficients of decision variables both in objective and constraint functions. ?-constraint method is applied to produce pareto optimal solutions comprising most preferred solution to satisfy all objectives. A numerical example is solved using our proposed method and the result so obtained is compared with that of fuzzy programming which justifies the efficiency and authenticity of the proposed method. � 2015, � Vilnius Gediminas Technical University, 2015.
Goal attainment method and Taylor series approximation to solve multi-objective linear fractional programming problem
(2015) Nayak S.; Ojha A.K.
This paper illustrates the use of goal attainment method with Taylor series approximation to produce a set of Pareto optimal solutions of a multi-objective linear fractional programming problem (MOLFPP). The relative gap in between the aspired goal and the feasible objective space is minimised along different search directions by introducing several non-negative and normalised weight vectors. To justify the effectiveness of our proposed method, a practical problem with numerical example is solved and the results are compared with that of existing fuzzy max-min operator method. � 2015 Inderscience Enterprises Ltd.
Improving Resistance of Masonry Structures to Tsunami Loading
(2016) Revanth D.; Akshay B.; Nayak S.; Dutta S.C.
The Asian tsunami of 26th December, 2004 took the lives of 2,20,000 people and devastated coastal structures, including many thousands of brick-built homes. Many economically backward people who have made their homes in non-engineered masonry lost their shelters. Though very high waves of tsunami cannot be resisted, waves comparable to the height of the masonry structures can be tolerated by these structures by implementing simple design techniques which are cost effective and can be implemented without any modern equipment. The present study throws light on the issues related to effect of brick orientation, number of openings, orientation and shape of the structures with respect to possible direction of wave movement and effect of support conditions upon the performance of masonry structures subjected to tsunami loading. It has also been noticed that boundary walls acts as a barrier to reduce the effect on the actual structures. In this context, this study may be helpful in framing design guidelines for improving the performance of non-engineered masonry structures under tsunami loading. � 2016, The Institution of Engineers (India).
Improving Seismic Performance of Masonry Structures with Openings by Polypropylene Bands and L-Shaped Reinforcing Bars
(2016) Nayak S.; Dutta S.C.
A previous study using a scaled-down model of single-room masonry structures tested on a shaking table has shown that strength may be considerably increased by tying up the masonry walls by polypropylene (PP) bands, wrapping the walls using steel wire mesh, and providing horizontal L-shaped reinforcing bars at corners. The effectiveness of the same economic approaches and their combinations has been studied for similar scaled-down models with proportionate openings representing doors and windows, as a logical further scope of the previous study testing these models on a shaking table. As the presence of openings influences the crack and damage propagation leading to failure, the present study may give a more realistic picture of the seismic behavior of masonry structures with openings. Experiments have shown that PP bands were more effective than horizontal L-shaped reinforcing bars in arresting cracks and preventing collapse of the models, even those severely damaged. Further, the most important aspect of the study is that the technique is economical and can be implemented without involvement of any technical manpower or sophisticated equipment. The interesting observations regarding the effectiveness of such economical strengthening measures obtained from the study may be helpful for seismic strengthening of real-life masonry structures with door and window openings, leading to broad guidelines in this direction. � 2015 American Society of Civil Engineers.
Investigation of ripple-limited low-field mobility in large-scale graphene nanoribbons
(2013) Luisier M.; Boykin T.B.; Ye Z.; Martini A.; Klimeck G.; Kharche N.; Jiang X.; Nayak S.
Combining molecular dynamics and quantum transport simulations, we study the degradation of mobility in graphene nanoribbons caused by substrate-induced ripples. First, the atom coordinates of large-scale structures are relaxed such that surface properties are consistent with those of graphene on a substrate. Then, the electron current and low-field mobility of the resulting non-flat nanoribbons are calculated within the Non-equilibrium Green's Function formalism in the coherent transport limit. An accurate tight-binding basis coupling the ?- and ?-bands of graphene is used for this purpose. It is found that the presence of ripples decreases the mobility of graphene nanoribbons on SiO2 below 3000 cm2/Vs, which is comparable to experimentally reported values. � 2013 AIP Publishing LLC.
Lateral period and seismic vulnerability of masonry buildings
(2014) Chandra Dutta S.; Nayak S.; Dinakar P.
The present paper compares the performance of some alternative methods of finite-element modelling and analytical formulation in the prediction of in-plane and out-of-plane stiffness and natural periods of masonry wall. It also aims to elaborate on the suitability of such techniques for masonry buildings through a number of case studies. While comparing these results with those predicted by relevant formula proposed by seismic codes of various countries, it has been observed that code formulas overestimate the periods considerably. The gap between the results from code formula and those from the analytical formulation is reduced if soil�structure interaction is incorporated in the analytical formulation, implying its suitability for predicting lateral period. Finally, the presented seismic safety assessment of masonry buildings for different combinations of number of storeys and bays may lead to valuable design insight. The study as a whole gave a good insight into effective finite-element modelling and seismic safety assessment of masonry buildings. � 2014, Thomas Telford Services Ltd. All rights reserved.
Mechanistic Insight into Enhanced Hydrogen Evolution Reaction Activity of Ultrathin Hexagonal Boron Nitride-Modified Pt Electrodes
(2018) Guha A.; Veettil Vineesh T.; Sekar A.; Narayanaru S.; Sahoo M.; Nayak S.; Chakraborty S.; Narayanan T.N.
Enhancing the intrinsic activity of a benchmarked electrocatalyst such as platinum (Pt) is highly intriguing from fundamental as well as applied perspectives. In this work, hydrogen evolution reaction (HER) activity of Pt electrodes, benchmarked HER catalysts, modified with ultrathin sheets of hexagonal boron nitride (h-BN) is studied in acidic medium (Pt/h-BN), and augmented HER performance, in terms of the overpotential at a 10 mA cm-2 current density (10 mV lower than that of Pt nanoparticles) and a lower Tafel slope (29 � 1 mV/decade), of the Pt/h-BN system is demonstrated. The effects of h-BN surface modification of bulk Pt as well as Pt nanoparticles are studied, and the origin of such an enhanced HER activity is probed using density functional theory-based calculations. The HER charge transfer resistance of h-BN-modified Pt is found to be drastically reduced, and this enhances the charge transfer kinetics of the Pt/h-BN system because of the synergistic interaction between h-BN and Pt. An enormous reduction in the hydrogen adsorption energy on h-BN monolayers is also found when they are placed over the Pt electrode [-2.51 eV (h-BN) to -0.25 eV (h-BN over Pt)]. Corrosion preventive atomic layers such as h-BN-protected Pt electrodes that perform better than Pt electrodes do open possibilities of benchmarked catalysts by simple modification of a surface via atomic layers. � 2018 American Chemical Society.
Mercury based drug in ancient India: The red sulfide of mercury in nanoscale
(2017) Mukhi P.; Mohapatra S.S.; Bhattacharjee M.; Ray K.K.; Muraleedharan T.S.; Arun A.; Sathyavathi R.; Juluri R.R.; Satyam P.V.; Panda A.K.; Biswas A.; Nayak S.; Bojja S.; Pratihar S.; Roy S.
Mercury is one of the elements which had attracted the attention of the chemists and physicians of ancient India and China. Among the various metal based drugs which utilize mercury, we became interested in the red sulfide of mercury which is known in ancient Indian literature as rasasindur (alias rasasindura, rasasindoor, rasasinduram, sindur, or sindoor) and is used extensively in various ailments and diseases. Following various physico-chemical characterizations it is concluded that rasasindur is chemically pure ?-HgS with Hg:S ratio as 1:1. Analysis of rasasindur vide Transmission Electron Microscopy (TEM) showed that the particles are in nanoscale. Bio-chemical studies of rasasindur were also demonstrated. It interacts with Bovine Serum Albumin (BSA) with an association constant of (9.76 � 0.56) � 103 M?1 and behaves as a protease inhibitor by inhibiting the proteolysis of BSA by trypsin. It also showed mild antioxidant properties. � 2017 Transdisciplinary University, Bangalore and World Ayurveda Foundation
Multi-objective linear fractional programming problem with fuzzy parameters
(2019) Nayak S.; Ojha A.K.
In this paper, a method is developed to derive the acceptable ranges of objective values for a multi-objective linear fractional programming problem(MOLFPP) with fuzzy parameters both in objectives and constraints. ? - and ? -cuts are respectively used in the objectives and constraints to specify the degrees of satisfaction and transform the fuzzy parameters into closed intervals. Using variable transformation and Taylor series expansion, the interval-valued fractional objectives are approximated by intervals of linear functions. The objective functions are assigned proper weights using analytic hierarchy process. Weighting sum method is used to transform the interval-valued multiple objectives into single objective. MOLFPP in interval-valued form is equivalently formulated as two linear problems which derive the acceptable ranges of objective values. Two numerical examples are illustrated to demonstrate the proposed method. � Springer Nature Singapore Pte Ltd. 2019.
On multi-level multi-objective linear fractional programming problem with interval parameters
(2019) Nayak S.; Ojha A.
This paper develops a method to solve multi-level multi-objective linear fractional programming problem (ML-MOLFPP) with interval parameters as the coefficients of decision variables and the constants involved in both the objectives and constraints. The objectives at each level are transformed into interval-valued fractional functions and approximated by intervals of linear functions using variable transformation and Taylor series expansion. Interval analysis and weighting sum method with analytic hierarchy process (AHP), are used to determine the non-dominated solutions at each level from which the aspiration values of the controlled decision variables are ascertained and linear fuzzy membership functions are constructed for all the objectives. Two multi-objective linear problems are equivalently formulated for the ML-MOLFPP with interval parameters and fuzzy goal programming is used to compute the optimal lower and upper bounds of all the objective values. A numerical example is solved to demonstrate the proposed solution approach. � EDP Sciences, ROADEF, SMAI 2019.
Polyvinyl Chloride Reinforced with Areca Sheath Fiber Composites�An Experimental Study
(2018) Nayak S.; Mohanty J.R.; Samal P.R.; Nanda B.K.
This research work deals with fibrous composites obtained by using treated and untreated areca sheath (AS) fibers reinforced in polyvinyl chloride (PVC) by injection molding process. Surface treatments of fibers have been carried out to have a better compatibility with PVC matrix. The tensile and flexural strength have been found to increase at the early stage with the increase in treated areca fiber content till optimum (18�wt% of fiber) fiber loading thereafter declines. At optimum fiber loading, the tensile strength, flexural strength and young�s modulus values are 42.38 MPa, 18.22 MPa and 2.38 GPa, respectively, which give maximum values in comparison to other fiber loadings. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), biodegradability tests and scanning electron microscopy (SEM) have been used for analysis. The TGA inferred that the thermal stability of the composites increased as compared to neat PVC matrix. Further, the composites exhibit excellent biodegradability property and their biodegradability increases with the increase of areca fiber content. From the properties obtained at optimum fiber loading (18�wt% of fiber), the composite can be suitable for automotive dashboard and door panel applications. � 2018, � 2018 Taylor & Francis.
Probing potential Li-ion battery electrolyte through first principles simulation of atomic clusters
(2018) Kushwaha A.K.; Sahoo M.R.; Nayak S.
Li-ion battery has wide area of application starting from low power consumer electronics to high power electric vehicles. However, their large scale application in electric vehicles requires further improvement due to their low specific power density which is an essential parameter and is closely related to the working potential windows of the battery system. Several studies have found that these parameters can be taken care of by considering different cathode/anode materials and electrolytes. Recently, a unique approach has been reported on the basis of cluster size in which the use of Li3 cluster has been suggested as a potential component of the battery electrode material. The cluster based approach significantly enhances the working electrode potential up to ?0.6V in the acetonitrile solvent. In the present work, using ab-initio quantum chemical calculation and the dielectric continuum model, we have investigated various dielectric solvent medium for the suitable electrolyte for the potential component Li3 cluster. This study suggests that high dielectric electrolytic solvent (ethylene carbonate and propylene carbonate) could be better for lithium cluster due to improvement in the total electrode potential in comparison to the other dielectric solvent. � 2018 Author(s).
A solution approach to multi-level nonlinear fractional programming problem
(2018) Nayak S.; Ojha A.K.
This paper studies multi-level nonlinear fractional programming problem (ML-NLFPP) of maximization type and proposes a solution approach which is based on the concept of fuzzy and simultaneous minimization, maximization of the objectives from their ideal, anti-ideal values, respectively. Nonlinear polynomial functions are considered as the numerators and denominators of the fractional objectives at each level. In the objective space, distance function or Euclidean metric is implemented to measure the distances between numerators, denominators and their ideal, anti-ideal values which need to be minimized and maximized. Goals for the controlled decision variables of upper levels are ascertained from the individual best optimal solutions of the corresponding levels, and tolerances are defined by decision makers to avoid the situation of decision deadlock. Fuzzy goal programming with reduction of only under-deviation from the highest membership value derives the best compromise solution of the concerned multi-level problem. An illustrative numerical example is discussed to demonstrate the solution approach and its effectiveness. � 2018, Springer Nature Singapore Pte Ltd.
Solution approach to multi-objective linear fractional programming problem using parametric functions
(2019) Nayak S.; Ojha A.K.
In this paper, an iterative technique based on the use of parametric functions is proposed to obtain the best preferred optimal solution of a multi-objective linear fractional programming problem. The decision maker ascertains own desired tolerance values for the objectives as termination constants and imposes them on each iteratively computed objective functions in terms of termination conditions. Each fractional objective is transformed into non-fractional parametric function using certain initial values of parameters. The parametric values are iteratively computed and ?-constraint method is used to obtain the pareto (weakly) optimal solutions in each step. The computations get terminated when all the termination conditions are satisfied at a pareto optimal solution of an iterative step. A numerical example is discussed at the end to illustrate the proposed method and fuzzy max�min operator method is applied to validate the obtained results. � 2019, Operational Research Society of India.