Chhatrapati Shivaji Institute of Technology

Durg, India

Chhatrapati Shivaji Institute of Technology

Durg, India
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Gupta P.K.,Chhatrapati Shivaji Institute of Technology
Carbon - Science and Technology | Year: 2016

Flow and temperature field inside a direct type solar dryer is investigated using Computational Fluid Dynamics (CFD). The coupled field analysis is carried out in ANSYS Fluent 12.0. The effect of location of inlet and outlet vents on the predicted velocity and temperature field of the air inside the dryer is analyzed. It is observed that a more uniform air flow and temperature distributions results for inlet vent location at bottom wall of drying chamber. © Applied Science Innovations Pvt. Ltd., India.


Gupta P.K.,Chhatrapati Shivaji Institute of Technology
Carbon - Science and Technology | Year: 2016

Low cost solar cookers are developed and tested. The paper discusses the methodology, development and testing of a reflective panel type low cost solar cooker. From the tests, it is found that such low cost solar cookers are dependable and viable alternative to cooking using conventional sources. The cooker is found suitable for cooking once in winter and twice in summer for 1-2 persons with the estimated cost of Indian Rs. 200.00. © Applied Science Innovations Pvt. Ltd., India.


Parappagoudar M.B.,Chhatrapati Shivaji Institute of Technology | Kodali S.P.,Koneru Lakshmaiah College of Engineering
Knowledge-Based Systems | Year: 2012

The development of an expert system for abrasive water jet machining (AWJM) process is considered in the present work. The expert system has been developed by using fuzzy logic (FL). It is to be noted that the performance of AWJM in terms of depth of cut depends on various process parameters, such as diameter of focusing nozzle, water pressure, abrasive mass flow rate and jet traverse speed. Three approaches have been developed to predict the depth of cut in AWJM using FL system. The first Approach deals with the construction of Mamdani-based fuzzy logic system. It is important to note that the performance of the FL depends on its knowledge base. In Approach 2, the data base and rule base of the FL-system are optimized, whereas in the third Approach, the total FL-system is evolved automatically. A binary-coded genetic algorithm has been used for the said purpose. The developed expert system eliminates the need of extensive experimental work, to select the most influential AWJM parameters on the depth of cut. The performances of the developed FL-systems have been tested to predict the depth of cut in AWJM process with the help of test cases. The prediction accuracy of the automatic FL-system (i.e. Approach 3) is found to be better than the other two approaches. © 2011 Elsevier B.V. All rights reserved.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Rani Durgavati University | Jha P.,Rani Durgavati University
Applied Physics Letters | Year: 2013

The long time dream of mechanoluminescence (ML) research to fabricate mechanoluminescence white light sources and mechanoluminescence displays seems to be turning into reality after the recent demonstration of highly bright and durable mechanoluminescent flexible composite films with a brightness of ≈120 cd/m2 and durability over ≈100 000 repeated mechanical stresses by using a combination of copper-doped zinc sulfide (ZnS:Cu) particles and polydimethylsiloxane. The present paper explores that self-recovery of mechanoluminescence of deforming piezoelectric semiconductors takes place by trapping of drifting charge carriers in the presence of piezoelectric field. This may be useful in enhancing the intensity and durability of ML devices. © 2013 AIP Publishing LLC.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Rani Durgavati University | Jha P.,Rani Durgavati University
Applied Physics Letters | Year: 2013

The luminescence induced by elastic deformation of solids, called the phenomenon of elastico-mechanoluminescence (EML), is observed in several materials. For applied pressure in the range of 17 MPa, certain crystals emit intense EML, which can be seen in day light with naked eye. In the present paper, we explore that, as the piezoelectric constant near the photo-generated electric dipoles formed by trapping of charge carriers in crystals is several times higher as compared to that at normal sites, the piezoelectrically induced detrapping of charge carriers and EML emission may take place for less value of the pressure applied onto the crystals. © 2013 AIP Publishing LLC.


Chandra B.P.,Pandit Ravishankar Shukla University | Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Jha P.,National Institute of Technology Raipur
Physica B: Condensed Matter | Year: 2015

Considering the detrapping of charge carriers due to reduction in trap-depth caused by piezoelectric field produced by applied pressure, an expression is derived for the detrapping rate of electrons. Then, an expression is obtained for the rate of generation of excited ions produced during capture of detrapped electrons by Eu3+ ions in persistent luminescent materials or by the energy released during electron-hole recombination in ZnS:Mn crystals. Finally, an expression is explored for the elastico-mechanoluminescence (EML) intensity, which is able to explain satisfactorily the characteristics of EML for the application of static pressure as well as for impact pressure. The total number of detrapped electrons and the total EML intensity are found to increase linearly with the electrostatic energy of the crystals in piezoelectric field. It is shown that the EML intensity should increase with the EML efficiency, number of crystallites (volume of sample), concentration of local piezoelectric regions in crystallites, piezoelectric constant of local piezoelectric regions, average length of the local piezoelectric regions, total number of electron traps, pressing rate, and applied pressure, and it should be higher for the materials having low value of threshold pressure and low value of trap-depth in unstressed condition. On the basis of the piezoelectrically-induced trap-depth reduction model of EML reported in the present investigation novel intense elastico mechanoluminescent materials having repetitive EML with undiminished intensity for successive loadings can be tailored which may find applications in sensing, imaging, lighting, colored displays, and other mechano-optical devices. © 2014 Elsevier B.V. All rights reserved.


Chandra B.P.,Rani Durgavati University | Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Jha P.,Rani Durgavati University
Journal of Luminescence | Year: 2013

A large number of noncentric and centric organic and inorganic crystals exhibit intrinsic and extrinsic fracto-mechanoluminescence (ML) due to the electron bombardment and electron-trapping mechanisms, and only a few crystals show ML due to the chemically induced fracto-ML and other possible mechanisms. The charged surfaces produced during fracture of solids owing to piezoelectrification, defective-phase piezoelectrification, movement of charged dislocations, baro-diffusion of defects near the crack-tip, and many other processes may cause production of very high electric field near the charged surfaces. In the case of non-photoluminescent and non-cathodoluminescent materials, the high energy electrons may be emitted from the charged surfaces and the electron bombardment (EB) mechanism may excite the molecules of surrounding gases and subsequently the gas discharge ML may be produced. In photoluminescent and cathodoluminescent solids, the electron bombardment may cause cathodoluminescence. In certain photoluminescent crystals, the light of gas discharge may excite photoluminescence. In many solids, the free electrons produced at fracture may be captured in the traps and consequently the electron-trapping (ET) mechanism may give rise to the light emission. Few solids may exhibit chemiluminescence because of the chemical reactions at the newly created surfaces. Some solids may exhibit black body radiations because of the high temperature produced near the tip of the moving cracks. Infrared radiation may also be emitted during the fracture of certain crystals. In certain solids, the gas discharge fracto-ML and the photoluminescence excited by the gas discharge disappear when the solids are fractured inside liquids; however, in certain solids the solid state fracto-ML appears even inside the liquids if they are not based on the processes involving gas discharge. Overall, depending on the prevailing conditions the ML spectra consist of either the gas discharge spectra or solid state luminescence spectra or the combination of the both. The fracto-ML of SrAl2O4:Eu, europium tetrakis (dibenzoyl methide) triethyl ammonium, ditriphenylphosphine oxide manganese bromide, freshly grown impure saccharin, etc. is so intense that it can be seen in day light with naked eye. The understanding of the mechanism of fracto-ML may be useful in preparing suitable fracto-mechanoluminescent materials and it may be helpful in designing the fracto-ML based devices such as fracture sensor, impact sensor, damage sensor, safety management monitoring system, fuse system for army warheads, etc. © 2012 Elsevier B.V.


Chandra B.P.,Rani Durgavati University | Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Jha P.,Rani Durgavati University
Applied Physics Letters | Year: 2014

The concepts of piezoelectric field dependence of the detrapping probability and lifetime of charge carriers in traps are developed. The charge carriers in traps become unstable after a particular piezoelectric field whereby more number of charge carriers are detrapped with increasing piezoelectric field. The detrapped electrons tunnel to the energy level of the hole-captured activator ions lying adjacent to the conduction band or tunnel to conduction band. Subsequently, luminescence is induced by the electron-hole recombination. Using these concepts microscopic theory of elastico-mechanoluminescent smart materials is explored. Present study may be useful in tailoring intense elastico-mechanoluminescent materials needed for different applications. © 2014 AIP Publishing LLC.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Disha Institute of Management and Technology
Optical Materials | Year: 2011

Whereas the elastico mechanoluminescence (EML) of certain crystals increases linearly with the stress, nonlinearity occurs in the EML intensity versus stress plot of several crystals. The EML of crystals can be understood on the basis of piezoelectrically-induced detrapping model, whereby the localized piezoelectric field causes detrapping of electrons or holes and subsequently the capture of electrons in the excited states of activator ions, recombination of electrons in hole captured centres, recombination of holes in electron-captured centres or simply the electron-hole recombination gives rise to the light emission. Considering the piezoelectrically-induced detrapping model of EML expression is derived for the stress dependence of the EML intensity. It is shown that the crystals having uniform distribution of traps show linear relationship between the EML intensity and stress and the crystals having exponential distribution of traps show nonlinear relationship between the EML intensity and stress. The crystals having linear dependence of EML intensity on stress are suitable for the fabrication of EML-based stress sensors. The values of coefficient of deformation detrapping, relaxation time of the crosshead of the machine used to deform the samples and lifetime of the charge carriers in the shallow traps lying in the normal piezoelectric region of the crystals can be determined from the EML measurements. The values of the coefficient of deformation detrapping are 0.310, 0.018 and 0.021 MPa-1 for SrMgAl6O11:Eu, Sr2MgSi2O 7:Eu and SrCaMgSi2O7:Eu crystals, respectively. The coefficient of deformation detrapping is low for SrAl2O 4:Eu, SrAl2O4:Eu, Dy, SrBaMgSi 2O7:Eu and ZnS:Mn crystals and such crystals are suitable for EML-based stress sensors. A good agreement is found between the theoretical and experimental results. © 2011 Elsevier B.V. All rights reserved.


Chandra V.K.,Chhatrapati Shivaji Institute of Technology | Chandra B.P.,Disha Institute of Management and Technology | Chandra B.P.,Ashoka Institute of Technology and Management
Journal of Luminescence | Year: 2012

When a composite of suitable dimension formed by mixing the microcrystalline or nanocrystalline persistent luminescent materials in epoxy resin is deformed at a fixed pressing rate, then the elastico mechanoluminescence (EML) emission takes place after a threshold pressure, in which the EML intensity increases linearly with the applied pressure. When the applied pressure is kept constant or decreased linearly, then the EML intensity decreases with time, in which depending on the prevailing condition, the EML intensity initially decreases at a fast rate and then at a slow rate or sometimes it decreases exponentially having only one decay time. When a small ball is dropped from a low height onto the film of a persistent luminescent material, then initially the EML intensity increases with time, attains a peak value and then it decreases initially at a fast rate and later on at a slow rate. In this case, both the peak EML intensity and the total EML intensity increase linearly with the height through which the ball is dropped onto the film. Considering the piezoelectrically induced detrapping model based on successive detrapping of exponentially distributed traps a theoretical approach is made to the dynamics of light emission induced by elastic deformation of persistent luminescent crystals and thin films. It is shown that the EML intensity depends on several parameters such as pressure, pressing rate or strain rate, temperature, density of filled electron traps, piezoelectric constant near defect centers, etc. Both, in the case of slow deformation and impact stress, the fast decay time is related to the time-constant for the decrease of pressing rate of the samples and the slow decay time of EML is related to the lifetime of electrons in the shallow traps lying in the normal piezoelectric region of the crystals. Both, the EML produced during the release of pressure and the EML produced during the successive applications of pressure take place due to the detrapping of retrapped electrons in the vacant electron traps near activator ions, in which retrapping is caused by the thermally released electrons from the filled shallow traps lying in the normal piezoelectric region of the crystals, which get filled during the detrapping of stable traps at the time of increase of pressure. On the basis of the proposed model, the dependence of EML intensity on different parameters, dynamics of EML and physical concepts of the threshold pressure, characteristic piezoelectric field for detrapping, coefficient of deformation detrapping, nonlinear increase of the EML intensity of some crystals at high pressure and higher EML intensity in the crystals having higher coefficient of deformation detrapping can be satisfactorily understood. A good agreement is found between the theoretical and experimental results. It is shown that the present study may be helpful in tailoring the intense persistent elastico mechanoluminescent materials having long lasting time. © 2011 Elsevier B.V. All rights reserved.

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