Wyniki wyszukiwania - Biblioteka Nauki

1

Three interfacial Griffith cracks between bonded dissimilar elastic media

100%

Das S.

International Journal of Applied Mechanics and Engineering

|

2001

|

tom Vol. 6, no 1

133-149

EN

The paper deals with three collinear Griffith cracks propagating with constant velocity under antiplane shear stress at the interface of an elastic layer of finite thickness h and a semi-infinite half plane of different elastic properties. The Fourier transform technique is used to reduce the elastodynamic problem to the solution of a set of integral equations which has been solved by using the finite Hilbert transform technique and Cooke's result. The analytical expressions for the stress intensity factors at the crack tips and crack opening displacements are obtained for large h. The graphical plots of these results are also presented for some particular cases.

2

A pair of equal collinear interfacial cracks between bonded dissimilar fixed isotropic layers

100%

Das S.

International Journal of Applied Mechanics and Engineering

|

2003

|

tom Vol. 8, no 2

167-175

EN

The problem of a pair of equal collinear Griffith cracks propagating with constant velocity under antiplane shear stress at the interface of two bonded dissimilar fixed isotropic layers has been considered. The method of Fourier transforms is employed and the problem is reduced to the solution of a singular integral equation, which has finally been solved numerically by using Chebyshev polynomials. The stress intensity factors at the crack tips and the crack opening displacement have been calculated numerically for some particular cases and displayed graphically.

3

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

71%

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

Geodesy and Cartography

|

2016

|

tom 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.

4

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

63%

Das S. , Saha G. C.

International Journal of Applied Mechanics and Engineering

|

2010

|

tom 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.

5

Kinetics and Mechanism of Base Hydrolysis of Some (Aminomonocarboxylato)(tetraethylenepentamine) Cobalt(III) Complexes in Aqueous Medium

63%

Das S. , Patnaik A. K.

Polish Journal of Chemistry

|

2009

|

tom Vol. 83, nr 3

455-466

EN

Base hydrolysis of some (aminomonocarboxylato)(tetraethylenepentamine)Cobalt(III) complexes were studied in aqueous medium. The pseudo-first order rate constant fitted the relationship. kobs = kOH[OH-]T at 0.005 [OH-] mol dm-3 0.10 at 293.15 K-313.15 K, (I = 0.1 mol dm-3), where kOH denotes the second order base hydrolysis rate constant. The alfa beta R isomer of the alfa-alaninato complex reacted approximately 8 times faster than its alfa beta S analogue at 298.15 K. Also the reactivity difference kOH(pyridine- 2-carboxy lato)/kOH(beta-alaninato) asymptotic to 3 for the (alfa beta S) isomer is indicative of the relative electron displacement property of the pyridine ring and the aliphatic chain attached to the bound carboxylate function which influences partly the Co-O bond strength. The Dcb mechanism is valid for all these substrates. The ionic strength dependence of kOH in the range 0.01 Less-than or equal to I, mol dm-3 Less-than or equal to 0.1 for glycinato and beta-alaninato complex also confirmed the relationship log kOH = log kOH 0 + S1[I1/2/(1 + I1/2) + CI], where C is an adjustible parameter S1 = 2bZAZB, with b = 0.509 at 298.15 K, ZA and ZB denote charges of the reactant species. The acid catalyzed aquation indicated that alfa beta R-[(tetren)CoO2C-(CH3)NH3]3+ aquates via spontaneous (ko) and acid catalyzed (kaq) path. However, these reactions are extremely slow (ko = (1.74š0.17)×10-5 s-1, kaq = (2.72 + 0.05)×10-5 dm3 mol-1 s-1 at 333.15 K and I = 1.0 mol dm-3). Key words: kinetics mechanism, base hydrolysis, stopped flow, (aminomono carboxylato)(tetraethylenepentamine)cobalt(III)

6

Weight function for a crack in an orthotropic medium under normal impact loading

63%

Mukherjee S. , Das S.

International Journal of Applied Mechanics and Engineering

|

2006

|

tom Vol. 11, no 4

915-928

EN

The paper deals with the investigation of an elastodynamic response of an infinite orthotropic medium containing a central crack under normal impact loading. Laplace and Fourier integral transforms are employed to reduce the dimensional wave propagation problem to the solution of a pair of dual integral equations in the Laplace transform plane. These integral equations are then reduced to integral differential equations which have been solved in the low frequency domain by method of iteration. To determine time dependence of the parameters, these equations are inverted to yield the dynamic stress intensity factor (SIF) for normal point force loading. These results have been used to obtain the SIF at the crack tip which corresponds to the weight function for the crack under normal loading. Analytical expressions of the weight function are used to derive SIF for polynomial loading. Numerical results of normalized SIF for a large normalized time variable and for different concentrated point force loading at an arbitrary location of the crack surface have been calculated for different orthotropic materials. In the present paper, a numerical Laplace inversion technique is used to recover the time dependence of the solution. Finally, the results obtained are displayed graphically.

7

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

63%

Das S. , Ghosh A.

Fibres & Textiles in Eastern Europe

|

2017

|

tom 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.

8

A pair of equal collinear interfacial griffith cracks

63%

Das S. , Patra B.

Applied Mechanics and Engineering

|

1999

|

tom Vol. 4, no 1

97-112

EN

The plane strain problem of determining stress intensity factors and crack energy for a pair of equal collinear moving Griffith cracks situated at the interface of two bonded dissimilar orthotropic half planes has been considered. The problem is reduced to solving a pair of simultaneous singular integral equations which have finally been solved by using Jacobi polynomials. Expressions for stress intensity factors and crack energy are obtained for some particular cases and the results are presented graphically.

9

Ocean acidification and marine microorganisms : responses and consequences

63%

Das S. , Mangwani N.

|

tom 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.

10

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

63%

Das S. , Ghosh A.

Fibres & Textiles in Eastern Europe

|

2015

|

tom 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.

11

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

63%

Rakshit M. , Das S.

Biocybernetics and Biomedical Engineering

|

2017

|

tom 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.

12

Interaction between three line cracks in a sandwiched orthotropic layer

63%

Das S. , Patra B.

Applied Mechanics and Engineering

|

1998

|

tom Vol. 3, no 2

249-269

EN

The paper deals with the interaction between three coplanar Griffith cracks located symmetrically in the mid plane of an orthotropic elastic layer of finite thickness 2h sandwiched between two identical orthotropic half planes. The Fourier Transform Technique is used to reduce the elastostatic problem to the solution of a set of integral equations which have been solved by using the finite Hilbert transform technique and Cook's result. The analytical expressions for the stress intensity factors and stress magnification factors at the crack tips are obtained for large h. Numerical results for stress intensity factors and stress magnification factors have been illustrated graphically.

13

Ocean acidification and marine microorganisms: responses and consequences

63%

Das S. , Mangwani N.

Oceanologia

|

2015

|

tom 57

|

nr 4

14

An anatomico-radiological study of an accessory mandibular foramen on the medial mandibular surface

63%

Das S. , Suri R. K.

Folia Morphologica

|

2004

|

tom 63

|

nr 4

EN

Unnamed foramina are known to be present in the mandible. The present research paper reports the presence of an accessory foramen on the medial surface of the mandible, highlighting its anatomico-radiological details. Accessory foramina in the mandible have been known to transmit branches of nerves supplying the roots of the teeth. Nerve block techniques by local anaesthetics might fail if any of these nerves or their branches pass through these accessory foramina and thus escape the nerve block. Dental surgeons performing extractions should be aware of accessory foramina on the mandible and thus plan anaesthesia at an appropriate anatomical site. The presence of such foramina might also be an alternate route for tumour spread following radiation therapy. Precise knowledge and awareness of such accessory mandibular foramina would therefore be important for dental surgeons performing nerve block and also for oncologists in planning radiation therapy.

15

Phylogenetic inference of Ericales based on plastid genomes and implication of cp-SSRs

54%

Hazra A. , Das S. , Bhattacharya S. , Sur S. , Sengupta C. , Das S.

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

|

2021

|

tom 102

|

nr 3

16

Data Clustering Using Multi-objective Differential Evolution Algorithms

51%

Suresh K. , Kundu D. , Ghosh S. , Das S.

Fundamenta Informaticae

|

2009

|

tom Vol. 97, nr 4

381-403

EN

The article considers the task of fuzzy clustering in a multi-objective optimization (MO) framework. It compares the relative performance of four recently developedmulti-objective variants of Differential Evolution (DE) on over the fuzzy clustering problem, where two conflicting fuzzy validity indices are simultaneously optimized. The resultant Pareto optimal set of solutions from each algorithm consists of a number of non-dominated solutions, from which the user can choose the most promising ones according to the problem specifications. A real-coded representation for the candidates is used for DE. A comparative study of four DE variants with two most well-known MO clustering techniques, namely the NSGA II (Non Dominated Sorting GA) and MOCK (Multi-Objective Clustering with an unknown number of clusters K) is also undertaken. Experimental results reported for six artificial and four real life datasets (including a microarray dataset of budding yeast) of varying range of complexities indicates that DE can serve as a promising algorithm for devising MO clustering techniques.

17

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

51%

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

International Journal of Applied Mechanics and Engineering

|

2010

|

tom 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.

18

Photosynthesis and antioxidative enzyme activities in five Indian mangroves with respect to their adaptability

51%

Dasgupta N. , Nandy P. , Das S.

Acta Physiologiae Plantarum

|

2011

|

tom 33

|

nr 3

EN

Five typical mangroves were taken (Bruguiera gymnorrhiza, Excoecaria agallocha, Heritiera fomes, Phoenix paludosa and Xylocarpus granatum) both from Sundarbans (in situ) and grown in a mesophytic environment (ex situ, in the Institute’s premises) for 12–15 years. A comparative account of PAR utilization for maximum photosynthesis, stomatal conductance and production of two antioxidant enzymes (peroxidase and Superoxide dismutase) were done between the in situ and ex situ habitats. The present work revealed that the average net photosynthesis was slightly higher in mangroves from non-saline habitats than that of the native ones. At the same time, stomatal conductances were remarkably reduced under salinity-stressed habitats when compared with those of the mesophytic counterparts, by 25–52%. Salinity imposed increase of antioxidant enzymes was observed. Both the investigated antioxidant enzymes showed considerable increase in saline-grown individuals and proved their efficient scavenging ability to evolve reactive oxygen species (ROS), but these increases were relatively lower in Heritiera and Xylocarpus even though the net photosynthesis was higher. This might be related to their lower adaptability under increased salinity stress than those of the other three species investigated.

19

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

51%

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

Materials Science Poland

|

2018

|

tom 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.

20

First report of twig blight of ban tulsi (Croton bonplandianus Bail.) caused by Choanephora cucurbitarum (Berk.and Ravenel) Thaxt. in India

51%

Das S. , Dutta S. , Ray S. K.

Journal of Plant Protection Research

|

2017

|

tom 57

|

nr 4

EN

In August 2015, twig blight disease of ban tulsi (Croton bonplandianus Bail.) caused by Choanephora cucurbitarum (Berk. & Ravenel) Thaxt. was observed for the first time, in the Gangetic alluvial region of West Bengal, India. A severe disease incidence (40–50%) showed twig blight symptoms starting with shoot apical meristem (SAM), leaf, and blossom blight symptoms. Typical symptoms were characterized by over-projecting black pin head like emerging sporangiola which formed mycelial cushion on the infected surface. The present report describes the identification of the causal pathogen as C. cucurbitarum based on its morphology and the internal transcribed spacer of its ribosomal DNA (rDNA – ITS) sequences with 100% identity of NCBI-GenBank published Choanephora database. Optimum temperatures, 28–30°C, coupled with high relative humidity (80–90%) during the monsoon season enhances the disease’s progress. To the best of our knowledge this is the first report of twig blight of C. bonplandianus, caused by C. cucurbitarum, in India as well as globally.