Wyniki wyszukiwania - BazTech

1

In-situ formed, ultrafine Al-Si composite materials: ductility

Guba P., Gesing A., Sokolowski J., Conle A., Sobiesiak A., Das S., Kasprzak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 92, nr 1-2

5--12

EN

Purpose: The work objective includes optimization of the casting production and heat treatment processes that will simultaneously maximize the combination of strength, hardness, and ductility for hypereutectic Al-Si compositions with Si volume fractions of as much as 25 vol.%. In addition, such an in-situ formed composite alloy will attain a unique combination of low production cost, high potential recycled content, and functional characteristics suitable for mission critical aerospace and vehicular applications. Design/methodology/approach: The unique High Pressure Die Casting Universal Metallurgical Simulator and Analyser (HPDC UMSA) was used for melting, cyclic melt treatment, and solidification of the hypereutectic Al-Si-X (A390). The produced as-cast structures contained colonies of nano-diameter Si whiskers and other morphologies, and absence of primary silicon particles. Heat treated structures rendered nano and ultrafine metal matrix composites. Findings: New developed as-cast Al-Si materials containing nano-diameter Si whiskers, without primary silicon particles required ultra short time heat treatment to result in nano and ultrafine metal matrix composite, rendering their hardness, strength and wear resistance, and the same time retaining toughness and ductility. Research limitations/implications: The cast samples were produced in laboratory conditions and potential tensile strength was estimated from empirical correlation with micro-hardness measurements. In the future, the comprehensive mechanical properties need to be tested. Practical implications: These ultrafine Si, Al-MMCs can be net-shape formed by modified HPDC technology or consolidated from spray-atomized alloy powder. Originality/value: Optimization of the entire production process for the hypereutectic Al-Si alloy compositions achieved a uniform distribution of ~ 25 vol.% of ultrafine Si particles in ductile FCC-Al matrix further reinforced by age hardening with nano-scale spinodal GP-zones. The associated mechanical property and ductility improvements will open a wide range of critical lightweighting components in transportation: aerospace, terrestrial vehicle and marine to the optimized hypereutectic Al-Si alloys. Presently, these components do not use the commercial HPDC A390 alloys due to their limited ductility and strength. Proposed new technology will allow conversion of various cast airspace alloys with ultrahigh mechanical properties to the automotive applications.

2

Dielectric relaxation and study of electrical conduction mechanism in BaZr0.1Ti0.9O3 ceramics by correlated barrier hopping model

Mondal T., Das S., Sinha T. P., Sarun P. M.

Materials Science Poland

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2018

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Vol. 36, No. 1

112--122

EN

This work aims to study the electrical conduction mechanism in the dielectric material BaZr0.1Ti0.9 O3 (BZT) ceramics by applying AC signal in the frequency range of 102 Hz to 106 Hz. The phase purity and microstructure of the sample have been studied by X-ray diffraction refinement and field-emission scanning electron microscope (FE-SEM) analysis. The appearance of resonance peaks in the loss tangent at high temperature is due to inherent dielectric relaxation processes of this oxide. The temperature dependent Cole-Cole plot has been studied in details to determine both the grain and grain boundary contribution to the conductivity. Electrical modulus analysis reveals that the hopping of charge carriers is the most probable conduction mechanism in BZT ceramics. The obtained data of AC conductivity obey the universal double power law and have been discussed in terms of microstructural network characteristics. The behavior of frequency exponent n of AC conductivity as a function of temperature verify the applicability of the correlated barrier hopping (CBH) model. The AC conductivity data are used to estimate the minimum hopping length, density of states at Fermi level, thermal conductivity and apparent activation energy. The value of activation energy confirms that the oxygen vacancies play a vital role in the conduction mechanism.

3

Parameters estimation and life cycle economic analysis of a PV powered tri-cycle in India

Das S., Sadhu P. K., Majhi A., Ghatak U., Bandyopadhya T.

Archives of Electrical Engineering

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2018

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Vol. 67, nr 3

655–-665

EN

This paper is devoted towards life cycle economic analysis (LCEA) of a solar photovoltaic (PV) powered tri-cycle. The paper is meant to propose a more systematic approach in determining the optimum use of scarce resources in order to determine the most cost-effective option of the solar tri-cycle. This analysis is based on the life cycle cost of this solar vehicle, involving its comparison with the customary fuel-based tri-cycle which exhibits the relatively less expenditure of the solar alternative. The economic analysis takes into account the fact that over 20 years, the overall price of solar component, replacement and electricity charges, is much lower as compared to that of a fuel-based tri-cycle in India taking into consideration the fuel cost, maintenance and annual inflation over the same period.

4

Chromophoric dissolved organic matter (CDOM) variability over the continental shelf of the northern Bay of Bengal

Das S., Das I., Giri S., Chanda A., Maity S., Lotliker A. A., Kumar T. S., Akhand A., Hazra S.

Oceanologia

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2017

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No. 59 (3)

271--282

EN

The present paper dealt with the annual dynamics of the absorption coefficient of chromophoric dissolved organic matter at 440 nm {aCDOM(440)} during February 2015 to January 2016 in the continental shelf of northern Bay of Bengal (nBoB) for the first time. Sea surface salinity (SSS), chlorophyll-a (Chl-a), total suspended matter (TSM) were also analyzed. It was hypothesized that CDOM should exhibit significant spatial and temporal variability in this region. aCDOM (440) and spectral slope ranged between 0.1002 m−1 – 0.6631 m−1 and 0.0071 nm−1 – 0.0229 nm−1 respectively during the entire study period. Higher values of aCDOM (440) were observed in the near shore stations and gradually decreased towards the offshore. Significant seasonal variability of aCDOM (440) was observed between the monsoon and non-monsoon seasons (p < 0.05). Thus the framed hypothesis was successfully accepted by means of the present study. The CDOM was mainly found to be of allochthonous character in this region. aCDOM (440) portrayed a significant negative linear relationship with SSS (R2 = 0.80; p < 0.05) implying conservative mixing of marine and terrestrial end members. However, examining the spatial variability of the relationship, it was observed that this relationship was significant only in the nearshore stations. While examining the seasonal variability of this relationship, it was found to be most significant during the monsoon (R2 = 0.81; p < 0.05). Thus it was inferred that whenever the SSS gradient was higher, the relationship between aCDOM (440) and SSS was found to be most significant.

5

Technique Based on Fuzzy Logic for Cotton Bale Lay-down Management

Das S., Ghosh A.

Fibres & Textiles in Eastern Europe

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2017

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Vol. 25, no. 2 (122)

30--33

EN

In this paper a new technique has been proposed for cotton bale management using fuzzy logic. The fuzzy c-means clustering algorithm has been applied for clustering cotton bales into 5 categories from 1200 randomly chosen bales of the J-34 variety. In order to cluster bales of different categories, eight fibre properties, viz., the strength, elongation, upper half mean length, length uniformity, short fibre content, micronaire, reflectance and yellowness of each bale have been considered. The fuzzy c-means clustering method is able to handle the haziness that may be present in the boundaries between adjacent classes of cotton bales as compared to the K-means clustering method. This method may be used as a convenient tool for the consistent picking of different bale mixes from any number of bales in a warehouse.

PL

W artykule zaproponowano nową technikę zarządzania składowaniem bawełny opartą na logice rozmytej. Badaniu poddano 1200 losowo wybranych bel bawełny. W celu pogrupowania bel w 5 kategoriach zbadano właściwości, tj. wytrzymałość, wydłużenie, średnią długość, jednorodność długości, zawartość włókien krótkich, dojrzałość, współczynnik odbicia i zażółcenie każdej beli. Opracowana metoda może być stosowana jako wygodne narzędzie do sortowania różnych mieszanek z dowolnej liczby bel w magazynie.

6

An efficient wavelet-based automated R-peaks detection method using Hilbert transform

Rakshit M., Das S.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 3

566--577

EN

Machine-aided detection of R-peaks is becoming a vital task to automate the diagnosis of critical cardiovascular ailments. R-peaks in Electrocardiogram (ECG) is one of the key segments for diagnosis of the cardiac disorder. By recognizing R-peaks, heart rate of the patient can be computed and from that point onwards heart rate variability (HRV), tachycardia, and bradycardia can also be determined. Most of the R-peaks detectors suffer due to non-stationary behaviors of the ECG signal. In this work, a wavelet transform based automated R-peaks detection method has been proposed. A wavelet-based multiresolution approach along with Shannon energy envelope estimator is utilized to eliminate the noises in ECG signal and enhance the QRS complexes. Then a Hilbert transform based peak finding logic is used to detect the R-peaks without employing any amplitude threshold. The efficiency of the proposed work is validated using all the ECG signals of MIT-BIH arrhythmia database, and it attains an average accuracy of 99.83%, sensitivity of 99.93%, positive predictivity of 99.91%, error rate of 0.17% and an average F-score of 0.9992. A close observation of the simulation and validation indicates that the suggested technique achieves superior performance indices compared to the existing methods for real ECG signal.

7

Mechanical Properties of a Bainitic Steel Producible by Hot Rolling

Rana R., Chen S., Haldar A., Das S.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2331--2338

EN

A carbide-free bainitic microstructure is suitable for achieving a combination of ultra high strength and high ductility. In this work, a steel containing nominally 0.34C-2Mn-1.5Si-1Cr (wt.%) was produced via industrial hot rolling and laboratory heat treatments. The austenitization (900°C, 30 min.) and austempering (300-400°C, 3 h) treatments were done in salt bath furnaces. The austempering treatments were designed to approximately simulate the coiling step, following hot rolling and run-out-table cooling, when the bainitic transformation would take place and certain amount of austenite would be stabilized due to suppression of carbide precipitation. The microstructures and various mechanical properties (tensile properties, bendability, flangeability, and room and subzero temperature impact toughness) relevant for applications were characterized. It was found that the mechanical properties were highly dependent on the stability of the retained austenite, presence of martensite in the microstructure and the size of the microstructural constituents. The highest amount of retained austenite (~ 27 wt.%) was obtained in the sample austempered at 375°C but due to lower austenite stability and coarser overall microstructure, the sample exhibited lower tensile ductility, bendability, flangeability and impact toughness. The sample austempered at 400°C also showed poor properties due to the presence of initial martensite and coarse microstructure. The best combination of mechanical properties was achieved for the samples austempered at 325-350°C with a lower amount of retained austenite but with the highest mechanical stability.

8

Earth observation and geospatial techniques for soil salinity and land capability assessment over Sundarban Bay of Bengal Coast, India

Das S., Choudhury M. R, Das S., Nagarajan M.

Geodesy and Cartography

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2016

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Vol. 65, no. 2

163--192

EN

To guarantee food security and job creation of small scale farmers to commercial farmers, unproductive farms in the South 24 PGS, West Bengal need land reform program to be restructured and evaluated for agricultural productivity. This study established a potential role of remote sensing and GIS for identification and mapping of salinity zone and spatial planning of agricultural land over the Basanti and Gosaba Islands(808.314sq. km) of South 24 PGS. District of West Bengal. The primary data i.e. soil pH, Electrical Conductivity (EC) and Sodium Absorption ratio (SAR) were obtained from soil samples of various GCP (Ground Control Points) locations collected at 50 mts. intervals by handheld GPS from 0–100 cm depths. The secondary information is acquired from the remotely sensed satellite data (LANDSAT ETM+) in different time scale and digital elevation model. The collected field samples were tested in the laboratory and were validated with Remote Sensing based digital indices analysisover the temporal satellite data to assess the potential changes due to over salinization. Soil physical properties such as texture, structure, depth and drainage condition is stored as attributes in a geographical soil database and linked with the soil map units. The thematic maps are integrated with climatic and terrain conditions of the area to produce land capability maps for paddy. Finally, The weighted overlay analysis was performed to assign theweights according to the importance of parameters taken into account for salineareaidentification and mapping to segregate higher, moderate, lower salinity zonesover the study area.

9

Analytical Solutions of Classical and Fractional KP-Burger Equation and Coupled KdV Equation

Ghosh U., Sarkar S., Das S.

Computational Methods in Science and Technology

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2016

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Vol. 22, No. 3

143--152

EN

Development of new analytical and numerical methods and their applications for solving non-linear partial differential equations (both classical and fractional) is a rising field of Applied Mathematical research because of its applications in Physical, Biological and Social Sciences. In this paper we have used a generalized Tanh method to find the exact solution of KP-Burger equation and coupled KdV equation. The fractional Sub-equation method has been used to find the solution of fractional KP-Burger equation and fractional coupled KdV equations. The exact solution obtained by the fractional sub-equation method reduces to classical solution when the order of fractional derivative tends to one. Finally numerical simulation has been done. The numerical simulation justifies that the solutions of two fractional differential equations reduce to shock solution for KP-Burger equation and soliton solution for coupled KdV equations when the order of derivative tends to one.

10

Ocean acidification and marine microorganisms : responses and consequences

Das S., Mangwani N.

Oceanologia

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2015

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No. 57 (4)

349--361

EN

Ocean acidification (OA) is one of the global issues caused by rising atmospheric CO2. The rising pCO2 and resulting pH decrease has altered ocean carbonate chemistry. Microbes are key components of marine environments involved in nutrient cycles and carbon flow in marine ecosystems. However, these marine microbes and the microbial processes are sensitive to ocean pH shift. Thus, OA affects the microbial diversity, primary productivity and trace gases emission in oceans. Apart from that, it can also manipulate the microbial activities such as quorum sensing, extracellular enzyme activity and nitrogen cycling. Short-term laboratory experiments, mesocosm studies and changing marine diversity scenarios have illustrated undesirable effects of OA on marine microorganisms and ecosystems. However, from the microbial perspective, the current understanding on effect of OA is based mainly on limited experimental studies. It is challenging to predict response of marine microbes based on such experiments for this complex process. To study the response of marine microbes towards OA, multiple approaches should be implemented by using functional genomics, new generation microscopy, small-scale interaction among organisms and/or between organic matter and organisms. This review focuses on the response of marine microorganisms to OA and the experimental approaches to investigate the effect of changing ocean carbonate chemistry on microbial mediated processes.

11

Cotton Fibre-to-Yarn Engineering: A Simulated Annealing Approach

Das S., Ghosh A.

Fibres & Textiles in Eastern Europe

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2015

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Vol. 23, no. 3 (111)

51--53

EN

In this paper we undertake to engineer yarn of predefined strength by choosing suitable raw material and process parameters. In an attempt to achieve a yarn of optimal strength, the constrained optimisation problem is formulated with the relation between raw material and yarn properties. Frydrych’s theoretical model of yarn strength is used for formulation of the optimisation problem. The simulated annealing (SA) method has been used to solve the optimisation problem by researching the best combination of raw material and process parameters that can bring into reality a yarn with the strength desired. The results show that SA is capable of ascertaining a set of parameters that gives the yarn strength desired.

PL

W pracy podjęto próbę otrzymywania przędzy o określonej wytrzymałości poprzez wybór odpowiedniego surowca i parametrów procesu przędzenia. W celu otrzymania przędzy o optymalnej wytrzymałości sformułowano problem optymalizacji zawierający zależności pomiędzy surowcem i właściwościami przędzy. Zastosowano przy tym teoretyczny model Frydrych wytrzymałości przędzy a także metodę symulacji SA. Udokumentowano, że za pomocą zastosowanej metody symulacji można sprecyzować zestaw parametrów, który umożliwia osiągniecie zakładanej wytrzymałości przędzy.

12

A Comparative Study of Hooks in the Yarns Produced by Different Spinning Technologies

Ghosh A., Das S., Mal P.

Autex Research Journal

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2015

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Vol. 15, no. 4

260--265

EN

This article presents a comparative study of hooks’ characteristics of ring, rotor, air-jet and open-end friction spun yarns. Hook types and their extent, spinning in-coefficient and mean fibre extent in the yarns produced on different spinning technologies are investigated. The results show that the hook extents for open-end friction spun yarn are the highest followed by rotor, ring and air-jet spun yarns. Ring and air-jet spun yarns have higher percentage and extent of trailing hook as compared with leading hook, whereas, rotor and friction spun yarns show the reverse trend.

13

Flame Retardant and Antimicrobial Jute Textile Using Sodium Metasilicate Nonahydrate

Basak S., Samanta K. K., Chattopadhyay S. K., Das S., Narkar R., Dsouza C., Shaikh A. H.

Polish Journal of Chemical Technology

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2014

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Vol. 16, nr 2

106--113

EN

Flame retardant and antimicrobial functionalities were imparted in jute textile using sodium metasilicate nonahydrate (SMSN), commonly known as “water glass”. Sodium metasilicate nonahydrate (SMSN) was applied in jute fabric in different concentration by padding method followed by drying. Flame retardancy of the fabric was evaluated by Limiting Oxygen Index (LOI) and burning behaviour under vertical flammability tester including the char length. Burning rate was found to decrease by almost 10 times after an application of 2% SMSN compared to the control sample. Thermogravimetry (TG) and differential scanning calorimetry (DSC) analysis of both the control and treated jute fabrics were utilized to understand the mechanism of developed flame retardance in jute fabric. It was observed that the SMSN treated samples showed excellent antimicrobial property against both gram positive and gram negative bacteria. Antimicrobial properties of both the control and treated jute fabrics were also measured quantitatively.

14

Group decision making using interval-valued intuitionistic fuzzy soft matrix and confident weight of experts

Das S., Kar S., Pal T.

Journal of Artificial Intelligence and Soft Computing Research

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2014

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Vol. 4, No. 1

57--77

EN

This article proposes an algorithmic approach for multiple attribute group decision making (MAGDM) problems using interval-valued intuitionistic fuzzy soft matrix (IVIFSM) and confident weight of experts. We propose a novel concept for assigning confident weights to the experts based on cardinals of interval-valued intuitionistic fuzzy soft sets (IVIFSSs). The confident weight is assigned to each of the experts based on their preferred attributes and opinions, which reduces the chances of biasness. Instead of using medical knowledgebase, the proposed algorithm mainly relies on the set of attributes preferred by the group of experts. To make the set of preferred attributes more important, we use combined choice matrix, which is combined with the individual IVIFSM to produce the corresponding product IVIFSM. This article uses IVIFSMs for representing the experts’ opinions. IVIFSM is the matrix representation of IVIFSS and IVIFSS is a natural combination of interval-valued intuitionistic fuzzy set (IVIFS) and soft set. Finally, the performance of the proposed algorithm is validated using a case study from real life.

15

A chaotic decomposition for generalized stochastic processes with independent values

Das S., Lytvynov E.

Probability and Mathematical Statistics

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2013

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Vol. 33, Fasc. 2

409--423

EN

We extend the result of Nualart and Schoutens on chaotic decomposition of the L2-space of a Lévy process to the case of a generalized stochastic processes with independent values.

16

Possibility of decreasing the activation energy of resistivity of mullite by doping with nickel ion

Roy D., Das S., Nandy P.

Materials Science Poland

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2012

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Vol. 30, No. 4

406--413

EN

Monophasic mullite samples doped with 0.002 M, 0.02 M, 0.1 M, 0.15 M and 0.2 M of NiCl2 were prepared via sol-gel technique. The prepared gels were dried, grinded, pressed into pellets and sintered at 400 °C, 800 °C, 1000 °C and 1300 °C. The electrical resistivity and activation energy of the composites have been measured and the variation of resistivity with concentration of the nickel ion doping has been investigated. The resistivity decreases with the concentration of nickel ions. X-ray analysis confirms the presence of Ni2+ ions in mullite. The Ni2+ ion, which substitutes Al3+ ion in the octahedral site of mullite structure, can be considered as an efficient factor in reducing the resistivity. The mullite unit cell parameters suggest predominant incorporation of NiCl2 in a glassy phase. The lowest activation energy of resistivity (Eact ) that was achieved is 1.22 eV at 0.02 M.

17

Kinetics and mechanism of electron transfer to pyridinium chlorochromate (VI) from sulfur containing amino acid, L-cysteine in aqueous and micellar media

Senapati S., Das S., Mohanty P., Patnaik A.K.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 2

6-10

EN

The electron transfer reaction of L-cysteine (RSH) with pyridinium chlorochromate (PCC) has been studied spectrophotometrically over the range 2.0 ≤ 10^3 [RSH] ≤ 6.0; 0.01 ≤ [H+] ≤ 0.2; 298 ≤ T ≤ 318 K and I = 0.3 mol dm-3 (NaClO4). The electron transfer reaction has also been carried out in the presence of anionic, cationic and neutral micelle. The reaction in acid medium is strongly catalyzed by changing [SDS]T (sodium dodecyl sulfate) up to 3 × 10-2 mol dm-3, beyond this concentration of SDS, the rate is retarded. The cationic and neutral micelle has a small effect on the rate. ΔH≠ (kJ mol-1) and ΔS≠ (JK-1 mol-1) values for the k1 and k2 paths are 30.20 ± 0.25, -159.65 ± 0.83 and 29.60 ± 0.62, -127.09 ± 2.17, respectively. The negative activation entropy is indicative of the ordered transition state for the electron transfer reaction. Formation of 2-amino-3-(2-amino-2-carboxy-ethyl) disulfanyl-propanoic acid as product is strongly supported by IR spectra.

18

Hall effects on oscillatory Couette flow

Ghara N., Maji S. L., Das S., Jana R. N.

International Journal of Applied Mechanics and Engineering

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2011

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Vol. 16, no. 4

1005-1020

EN

Hall effects on the oscillatory Couette flow between two horizontal parallel plates are studied. One of the plate is at rest and the other one oscillates in its own plane. The effects of Hall and frequency parameters on the velocities and the shear stresses for the steady and unsteady flows are analyzed. It is found that the shear stresses at the M stationary plate due to the unsteady primary and secondary velocities have a phase lag over the plate oscillations for those values of the Hall parameter m, Hartmann number and the frequency parameter , we have considered.

19

Herschel - Bulkley model for two-phase blood flow in narrow vessel

Das S., Saha G. C.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no. 1

19-34

EN

A mathematical model for a two-phase blood flow through a circular narrow vessel has been developed by considering blood to be a non-Newtonian liquid of Herschel-Bulkley type and taking into consideration the slip velocity at the wall of the vessel. Analytical expressions for velocities of blood in the peripheral layer and central core layer, flow rate and apparent fluidity of blood have been obtained and their natures are portrayed graphically for different parameters.

20

Hall effects on unsteady MHD flow between two disks with non-coincident parallel axes of rotation

Das S., Maji M., Guria M., Jana R. N.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no. 1

5-18

EN

Hall effects on the unsteady MHD flow of a viscous incompressible electrically conducting fluid between two disks with reference to non-coaxial parallel axes of rotation have been studied. It is rigorously stated that there arises an axisymmetric solution of this problem as referred to a rigid body rotation. An exact solution of the governing equation has been obtained by applying the Laplace transform technique. It is found that the torque experienced by the disks decreases with an increase in the Hall parameter, m.