Growth of CdS and CdTe thin films for the fabrication of n-CdS/p-CdTe solar cell

R.K.Sharma,KiranJain,A.C.Rastogi 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3

Thin n-CdS and p-CdTe lms were prepared by chemical spray pyrolysis and electrochemical deposition respectively. Excessivesulphur in the spray solution has promoted grain growth in CdS film. Microstructural features of CdS film with stoichiometric Cd:Sformity, reduced grain boundary losses of current and improved shunt resistance through inhibition of leakage of current at narrowgrain boundary or void site is expected and is indeed observed. Electrodeposition of CdTe films, beside the eect of the inherentprocess parameters, is also aected by crystalline and microstructural features of the underlyingCdS. Nucleation of CdTe film isremarkably aected by CdS film spray deposited over glass substrate. Cell performance considerably depends upon the windowlayer CdS and the properties of sprayed CdS film depends considerably on the Cd:S ratio in the spray solution. A higher S content inCdS film resistivity. A typical increase in cell eciency was found to increase from 8% to 10.5% usingCdS film with Cd:S ratio as1:1.1 and 1:1.3 respectively.. 2002 Elsevier Science B.V. All rights reserved.

Optical properties of CdS nanoclusters: effects of size, stoichiometry and alloying with Ag2S

R.K.Sharma,S.N.Sharma,A.C.Rastogi 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3

The optical absorption and photoluminescence (PL) properties of nanosize CdS clusters synthesized by chemical bath depositiontechnique using precursor chemicals of high purity CdCl2, thiourea and NH4by the reaction rate, concentration of the reactants of the chemical bath and thickness of the lm. Relative to bulk crystals, the bandgap (Eg . 2:5 eV) of CdS clusters is signicantly blue-shifted with decreasing cluster size. CdS nanoclusters present a mixed hexa-gonal/cubic structure, which indicates that CdS formation occurs primarily via ‘‘ion-to-ion’’ process. Scanning electron micro-scopic studies of CdS lms revealed that the lms are composed of domains, which are formed from the coalescence of smallerAg2S alloying with the CdS nanoclusters show that surface related states of one material can be excited through states of a dierentinterior material.. 2002 Elsevier Science B.V. All rights reserved.

Vibration analysis for detecting failure mode and crack location in first stage gas turbine blade

S. Rani,A. K. Agrawal,V. Rastogi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Structure frequency response testing “modal analysis” is an integral part of the development and testing of structures such as pistons, turbine blades, compressor blades, crankshafts, and connecting rods. The usefulness of this technique lies in the fact that the energy in an impulse input is distributed continuously in the frequency domain. Thus, an impulse force will excite all resonances within given frequency range. To detect a fault in the structure, one may require frequency response functions (FRFs) of structures in both conditions, before (healthy structure) and after (failed structure) fault occurs. Now by extracting modal properties from collected FRFs and by comparing modal properties, one can detect and locate the structural faults. A case study is presented in order to detect failure mode and locate cracks on a 30 MW first stage gas turbine blade made of nickel based super alloy IN738LC, which has failed after rendering a useful life of 72000 h. The root causes of failure are detected by comparing the failed blade experimental model with the failed blade computational model. It is observed that the frequencies of the real failed blade experimental model are lesser than the computational model of the failed turbine blade. This is due to the metallurgical defects, which result in loosening of stiffness at the leading and trailing edges of the blade. Further, the stress concentration areas noticed on leading and trailing edges in computational model of the failed blade at the sixth mode are well corroborated with the cracked zone seen on leading and trailing edges of a real case failed turbine blade, collected from the site. It is concluded that the blade has failed due to that the resonance at sixth modal frequency. Scanning electron microscope (SEM) images reveal the presence of corrosion pits on the surfaces of the turbine blade that lead to surface degradation, which results in crack initiation and its propagation with high-cycle fatigue. It is concluded that the failure of turbine blade occurs due to high cycle fatigue.

Groundwater Estimation using Global Strong Form Collocation-based Meshfree Method in a Field like Synthetic Confined Aquifer Domain

Sharad Patel,A. K. Rastogi 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6

Most of the groundwater simulation models are based on certain element (finite element method) or grid (finite difference method) formulation which is used for obtaining the transient head variation in the aquifer system. Since groundwater management scenarios often demand to call these simulation models several hundred times to deliver the acceptable decision variables, it is essential that an efficient and accurate system simulation technique should be adopted. In this paper, a recently developed global collocation approach based meshfree (Mfree) model is used as a groundwater state estimation tool. The developed model is first tested on a twodimensional confined aquifer synthetic flow problem where the results are compared with the available analytical and numerical solutions. Different time steps and varied pumping schedules were also assessed for a performance check. Later the tested model is applied to a synthetic aquifer flow problem having a close analogy to real field variability. The results obtained through the projected Mfree model are the testimony of accuracy and successful application of the developed model.

Electrochemical deposition and characterization of cadmium indium telluride thin films for photovoltaic application

KiranJain,R.K.Sharma,SandeepKohli,K.N.Sood,A.C.Rastogi 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3

Cd-In-Te films were electro-deposited potentiostatically over SnO2:F coated glass substrates from aqueous acidic solutionscontainingCdSO 4, InCl3 and TeO2 at 85 .C. Cyclic voltammetric studies were carried out to study the growth process and thepotential range for ternary CdInTe thin film deposition. Crystalline structure and surface morphological studies were carried outOptical transmission studies showed a direct band structure and the band gap of the deposited film change with the depositionpotential. A typical decrease from 1.2 to 1.1 eV in the optical band gap was observed on increasing the cathodic deposition potentialfrom)0.5 to)0.54 V (SCE).. 2002 Elsevier Science B.V. All rights reserved.

Application of multivariate analysis to determine spatial and temporal changes in water quality after new channel construction in the Chilika Lagoon

Kim, J.Y.,Bhatta, K.,Rastogi, G.,Muduli, P.R.,Do, Y.,Kim, D.K.,Pattnaik, A.K.,Joo, G.J. Elsevier Science 2016 Ecological engineering Vol.90 No.-

<P>Lagoon ecosystems have been severely degraded by anthropogenic activities, which result in ecological and hydrological changes in the system. Detailed understanding of the recovery processes of restored lagoon systems has been impeded by the underlying complexity of integral environmental components. The aim of this study was to understand relationships between water quality variables in a restored lagoon, and temporal and spatial changes at each recovery stage after lagoon restoration. Ten water quality parameters were monitored on a monthly basis at 30 sampling sites in the Chilika Lagoon from 1999 to 2009. Self-Organizing Map and principal component analyses showed that salinity was the dominant factor for the Chilika Lagoon and had maximal component loading in the principal component analysis. Mean salinity level increased after opening of a new mouth in the study site, however, a decreasing trend was observed 4 years after the restoration. The pH and pCO(2) exhibited pulse-type resilience after the restoration event. The average nitrate:phosphate ratio increased steadily during the monitoring period. Multivariate analysis of monitoring data of the restoration site provided a deep understanding of its temporal and spatial change. It would be worthwhile to extend multivariate analysis to diverse ecosystems, while considering biological components is recommended in order to evaluate the comprehensive response of the restored system. (C) 2016 Elsevier B.V. All rights reserved.</P>

NUMERICAL STRATEGIES TO CHECK THE OF SALT WATER INTRUSION IN CONFINED COASTAL AQUIFER

UKARANDE DR. S. K.,RASTOGI A. K. 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Electrochemically deposited bismuth telluride thin films

SantoshGolia,M.Arora,R.K.Sharma,A.C.Rastogi 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3

Thin films ofbismuth telluride grown by electrochemical deposition technique on conducting glass and Mo sheet substrates, werecharacterized for their structural, morphological, optical and compositional analysis. These studies revealed polycrystalline an-isotropic and layered structure ofthese lms with dierent compositional stoichiometry. In the present work electrochemical de-application since it has a narrow optical energy band gap of0.13 eV. In this deposition process dierent lm growth parameters wereoptimized to get good quality ofcompositionally uniform bismuth telluride thin lm. XRD analysis revealed a hexagonal symmetrywith largec-axis lattice constants (Bi2Te3, B i2þ XTe3. X).. 2002 Elsevier Science B.V. All rights reserved.

Statistical Optimization of Medium Composition for Bacterial Cellulose Production by Gluconacetobacter hansenii UAC09 Using Coffee Cherry Husk Extract - an Agro-Industry Waste

( Rani Mahadevaswamy Usha ),( Navin K. Rastogi ),( K. A. Anu Appaiah ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.7

During the production of grape wine, the formation of thick leathery pellicle/bacterial cellulose (BC) at the air-liquid interface was due to the bacterium, which was isolated and identified as Gluconacetobacter hansenii UAC09. Cultural conditions for bacterial cellulose production from G. hansenii UAC09 were optimized by central composite rotatable experimental design. To economize the BC production, coffee cherry husk (CCH) extract and corn steep liquor (CSL) were used as less expensive sources of carbon and nitrogen, respectively. CCH and CSL are byproducts from the coffee processing and starch processing industry, respectively. The interactions between pH (4.5- 8.5), CSL (2-10%), alcohol (0.5-2%), acetic acid (0.5- 2%), and water dilution rate to CCH ratio (1:1 to 1:5) were studied using response surface methodology. The optimum conditions for maximum BC production were pH (6.64), CSL (10%), alcohol (0.5%), acetic acid (1.13%), and water to CCH ratio (1:1). After 2 weeks of fermentation, the amount of BC produced was 6.24 g/l. This yield was comparable to the predicted value of 6.09 g/l. This is the first report on the optimization of the fermentation medium by RSM using CCH extract as the carbon source for BC production by G. hansenii UAC09.

STURCUTURE INDUCED MODIFICATION IN THE FERROELECTRIC AND CURRENT CONDUTION BEHAVIOUR OF PZT THIN FILMS

Ramezani daevish, S.,Rastogi, A.C.,Bhatnagar, P.K. 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.2 No.e3

Crystalline structure induced effecs on the ferroelectric and current conduction properties in electron beam deposited PZT thin films are described. $TiO_2$ dispersion in PZT reduces dielectric constant and charge storage density to 270 and $3.5\;{\mu}C/cm^2$ and increases carrier density. Pyrochlore PZT inclusion cause further reduction to 60 and $77fC/cm^2$ but have no effect on the microscpic polarization. Activated conduction energy 0.25-0.3eV is observed in $TiO_2$ mixed PZT. Low field conduction is ohmic and changes to space charge limited at a threshold field $8{\times}10^4\;V/cm$. Inclusion of pyrochlore phase causes deep traps ${\thickapprox}5{\times}10^18cm^-3$ and increased hole density of ${\thickapprox}\;3{\times}10^11\;cm^-3$.