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Damage assessment of structures from changes in natural frequencies using genetic algorithm
Maity, Damodar,Tripathy, Rashmi Ranjan Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.1
A method is presented to detect and assess the structural damage from changes in natural frequencies using Genetic Algorithm (GA). Using the natural frequencies of the structure, it is possible to formulate the inverse problem in optimization terms and then to utilize a solution procedure employing GA to assess the damages. The technique has been applied to a cantilever beam and a plane frame, each one with different damage scenario to study the efficiency of the developed algorithm. A laboratory tested data has been used to verify the proposed algorithm. The study indicates the potentiality of the developed code to solve a wide range of inverse identification problems in a systematic way. The outcomes show that this method can detect and estimate the amount of damages with satisfactory precision.
On Semirings which are Distributive Lattices of Rings
Maity, S.K. Department of Mathematics 2005 Kyungpook mathematical journal Vol.45 No.1
We introduce the notions of nilpotent element, quasi-regular element in a semiring which is a distributive lattice of rings. The concept of Jacobson radical is introduced for this kind of semirings.
Evaluation of Hepatoprotective Potential of Cassia tora Leaf Extract
Maity, Tapan Kumar,Mandal, Subhash C.,Mukherjee, Pulok K.,Saha, Kakali,Das, J.,Saha, B.P.,Pal, M. The Korean Society of Pharmacognosy 1997 Natural Product Sciences Vol.3 No.2
Methanolic extract of the leaves of Cassia tom was evaluated for its hepatoprotective potentials in rats by inducing hepatotoxicity with carbon tetrachloride. The extract at a dose of 400 mg/kg orally showed significant protective effect by lowering the serum levels of transaminase (SGOT and SGPT), bilirubin and alkaline phosphatase (ALP). The effects produced were comparable to that of a standard hepatoprotective agent.
Binary complexes of tertiary amines with phenylacetylene. Dispersion wins over electrostatics
Maity, Surajit,Patwari, G. Naresh,Karthikeyan, S.,Kim, Kwang S. Royal Society of Chemistry 2010 Physical chemistry chemical physics Vol.12 No.23
<P>The structures of the binary complexes between phenylacetylene and several tertiary amines <I>viz</I>., triethylamine, 1-ethylpiperidine, 1-ethylpiperazine, 1-azabicyclo[2.2.2]octane, and 1,4-diazabicyclo[2.2.2]octane were inferred using infrared-optical double resonance spectroscopy. The IR spectra in the acetylenic C–H stretching region clearly rule out the formation of electrostatic dominated C–H⋯N hydrogen bonded complexes. The IR spectra also point to the fact that all the five tertiary amines interact with the extended π electron density of the phenylacetylene moiety, leading to the formation of multidentate C–H⋯π hydrogen bonded complexes. Additionally a very weak electrostatic C–H⋯N hydrogen bond enhances the stability of the complex marginally. The multidentate C–H⋯π hydrogen bonded complexes are stabilized by a substantial contribution from the dispersion energy.</P> <P>Graphic Abstract</P><P>The fluorescence detected infrared spectra suggest that 1,4-diazabicyclo[2.2.2]octane interacts with phenylacetylene <I>via</I> dispersion dominated multiple C–H⋯π hydrogen bonds. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b918013c'> </P>
Comparative study of torsional wave profiles through stratified media with fluted boundaries
Manisha Maity,Santimoy Kundu,Alka Kumari,Shishir Gupta 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.1
A mathematical analysis has been carried out for understanding the traversal attributes of torsional waves in a Voigt-type viscoelastic porous layer bounded with corrugated surfaces resting over a heterogeneous transversely isotropic gravitating semi-infinite medium. Both the media are assumed to be under the effect of initial stresses acting along horizontal directions. In the presumed geometry, continuous and periodic type of corrugation has been considered. The condensed form of dispersion relation has been obtained analytically with the aid of the Whittaker’s function and suitable boundary conditions. The influence of viscoelasticity, porosity, initial stresses, heterogeneity, gravity, undulation and position parameters on the phase and damped velocities has been illustrated graphically. In addition, relative examination investigating the impact of corrugated and planar bounded surfaces on the dispersion and damping characteristics is one of the important highlights of this study.
Reshmi Maity,N. P. Maity,Srinivasa Rao Karumuri,Girija Sravani,K. Guha 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6
The output acoustic energy of a capacitive micromachined ultrasonic transducer (CMUT) can be enhanced by adjusting its membrane structure. In this paper three dissimilar membranes shapes of CMUT: circular, rectangular and hexagonal, were aimed and 3D finite element method simulated using adaptive meshing technique. The displacement as well as strain and stress outputs for a single membrane and an array of four membranes on a single substrate were obtained. The simulated results are supported by analytical modeling. A static bias of 40 V and a signal of amplitude 100 mV are employed. A pressure of 8603.98 N/m 2 resulting in a force of 16.894 μN was applied at the membrane. Fixtures were provided on every possible face of the structure except the face 1 (membrane). The outcomes showed that the membrane displacement is highest for a circular geometry under same uniform pressure and area of vibration. Moreover as the distance between the elemental membranes increases the displacement decreases for circular and hexagonal membranes while the reverse behavior is observed for rectangular membranes.
Reshmi Maity,N. P. Maity,K. Srinivasa Rao,Girija Sravani,K. Guha,S. Baishya 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.5
This paper models the fringing fi eld eff ects in a capacitive micromachined ultrasonic transducer (CMUT) structure for determining the sensitivity of the device. CMUT is used as a medical imaging component which can be an important module for sustainable healthcare system. The capacitance value of the device is evaluated based on Younes Ataiiyan’s method. To determine the equivalent capacitance of the device, the capacitances of the membrane, gap and silicon nitride insulating layer are associated in series. Mason’s modeling techniques are used to evaluate the membrane displacement. Circular membrane approximation model has been considered. Eff ects of the variation in membrane thickness, gap separation, and membrane radius on membrane displacement are investigated. The analytical prediction has been validated with the finite element method simulation results through PZFlex. Three dimensional modeling is carried out to accurately capture the characteristic behavior of the device. The agreements of both results are excellent which verifi es that fringing field effects exist in the device operation.
Supratim Maity,Nirmalya Sankar Das,Saswati Santra,D. Sen,Kalyan Kumar Chattopadhyay 한국물리학회 2016 Current Applied Physics Vol.16 No.10
Carbon nanotubes (CNTs) are the most famous cold cathodes for display technology. However, graphene and other two dimensional carbon nanostructures and advanced II-VI semiconductor nanostructures are strongly emerging as strong competitors challenging the well established performance of CNTs in this field. Hence several technologies to improve field emission (FE) properties of CNTs are being developed. Here we report a facile technique to improve the cold emission performance of multiwalled CNTs (MWCNTs) by coating the same with chalcogenide semiconductor. MWCNT thin films were synthesized via chemical vapor deposition (CVD) technique and the same was coated by cadmium sulfide (CdS) nanoparticles via radio frequency magnetron sputtering technique. The pure and coated thin films were characterized by Fourier transform infrared spectroscopy and Raman spectroscopy to confirm presence of CdS on CNT surfaces. X-ray photoelectron spectroscopy revealed the compositional and valance state information of the as prepared samples. Field emission scanning electron microscopy and high resolution transmission electron microscopic studies were carried out to obtain information regarding morphology and nanocrystallinity of the CNTs and the coated CdS nanoparticles. Field assisted electron emission of pristine CNTs developed significantly with improved turn-on field and very high current density by CdS nanoparticle coating.
Chiranjit Maity,Saptadip Samanta,Suman K. Halder,Pradeep K. Das Mohapatra,Bikas R. Pati,Malabendu Jana,Keshab C. Mondal 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.2
The aim of this study was to produce two isozymes of α-amylase by immobilization of a newly isolated soil bacterium. The bacterium was identified as Bacillus thuringiensis CKB19 on the basis of its 16S rRNA profile. Enzyme production by free cells increased linearly with cell growth up to 34 h in starch containing enriched liquid media. The active bacterial cells were immobilized in Caalginate beads, and operational stability of the entrapped cell was optimized for amylase production. Enzyme production was optimal at an alginate concentration of 2 g%(w/v), calcium chloride concentration of 1 M, and with 300beads (each bead contained 2 × 10^7 cells)/250 mL flask. Amylase production by the immobilized cells was about 3times higher than free cell fermentation after 34 h of incubation. It was observed that the immobilized bacterium secreted two different amylases (Am-I and Am-II) into the culture fluid. The molecular masses of Am-I and Am-II were 59.6 and 44.7 kd, respectively, and showed optimum activity at pH 5.0 and 9.0. Both amylases showed optimum activity at 40℃ and were stable at the same temperature,with losses of only 10 and 20% (for Am I and Am II,respectively) of their original activities after 24 h of incubation. Further, both amylases were salt tolerant (up to 4 M NaCl) and hydrolyzed raw starchy foods into glucose. All these characteristics make this enzyme mixture suitable for use as a digestive aid and for the improvement of digestibility of animal feed ingredients.