Browse Items (11858 total)
Sort by:
-
Review on persistent challenges of perovskite solar cells stability
Today Perovskite solar cell (PSC) has achieved efficiency close to 26%, surpassing the efficiencies of well- known Dye-Sensitized Solar cells (DSSC), CdTe-based solar cells, etc. Ease of preparing perovskite solutions and convenient deposition technique has given them added advantage over other contemporary competitors. This has also made them an economically feasible option. Since the inception of PSCs in 2009, a lot of improvements have been done in various aspects like composition, synthesis technique, fabrication method, and interface study. However, today it is crucial to think about the commercialization of PSCs. In this direction, the stability of PSCs has been a long-standing question. This review focuses on the key aspects of perovskite stability. Challenges posed by environmental factors like moisture, oxygen, temperature, and light are still unanswered. The lead toxicity of PSCs demands a potential substitute of lead with no compromise in their efficiency. The lead-free approach of PSCs and their commercialization has been discussed separately. A suitable emphasis has been given to the encapsulation of solar cells, as we find it a necessary part of the future commercialization process. This review has been addressed with an ideology to provide overall knowledge on the stability issues and challenges concerned with the PSCs, to attract young research community towards this emerging field. 2021 International Solar Energy Society -
-
-
-
An Empirical Analysis of Price Discovery in Spot and Futures Market of Gold in India
The broadest classification of the Indian financial market can be made in terms of commodity market, stock and security markets and foreign exchange market. Commodity markets are markets where raw or primary products are exchanged. These raw commodities are traded on regulated commodity exchanges, in which they are bought and sold in standardized contracts. Gold is a commodity which has been undergoing very serious price fluctuations in recent years. It has had its own impact on commodity trading too. Price discovery process of gold has always been a matter of wide discussion among researchers and policy makers. In this context this study aims at analyzing the price discovery process of Gold in Indian commodity market. It also looks into the volatility impact of futures price on spot price as well as the volatility impact of spot price on futures price. The study is completely based on the secondary data collected from the official website of NCDEX. The data extend for a period ranging from 23rd April 2009 to 29th December 2011. The daily data of spot and futures prices of gold during the period is taken into account. Various econometric tools are employed to test the hypotheses set. The VAR model result confirms the unidirectional relationship runs from the spot market to the futures market of gold in India. It reveals co integration and dynamic relationship between spot and futures markets of gold. The result of GARCH model implies that both futures as well as spot markets do have significant impact in the price volatility of gold in India. The result of VECM tells that spot market is dominant in the price discovery process which is a clear indication of the fact that spot market of gold is information efficient in India. The result is of great significance for the investors who wish to improve portfolio performance. With regard to policy making, a better understanding of the interconnectedness of these markets would be useful for the policy makers who coordinate the stability of financial markets. For marketers, it provides a reliable forecast of spot prices in the future to allow them to effectively manage their risks in the production or marketing process. The unprecedented uptrend in the price of gold and high volatility in recent years provides room for some important social implications. -
EFFECT OF SECOND SOUND ON THE ONSET OF RAYLEIGH-B??NARD-MARANGONI MAGNETO CONVECTION
The effects resulting from the substitution of the classical Fourier law by the non-classical Maxwell-Cattaneo law in Rayleigh-B??nard-Marangoni convection in an electrically conducting Newtonian fluid are studied using the Galerkin technique. In the case of Rayleigh??B??nard convection, the eigenvalue is obtained for free-free, rigid-free and rigid-rigid velocity boundary combinations with isothermal and adiabatic boundaries. In the case of Marangoni and Rayleigh-B??nard-Marangoni convection the eigenvalues are obtained for an upper free / adiabatic and a lower rigid / isothermal boundaries. A linear stability analysis is performed. The influence of various parameters on the onset of convection has been analyzed. The classical approach predicts an infinite speed for the propagation of heat. The present non-classical theory involves a wave type heat transport (SECOND SOUND) and does not suffer from the physically unacceptable drawback of infinite heat propagation speed. It is found that the results are noteworthy at short times and the critical eigenvalues are less than the classical ones. -
Zone based relative density feature extraction algorithm for unconstrained handwritten numeral recognition /
Journal of Theoretical and Applied Information Technology, Vol.64, Issue 1, pp.304-314, ISSN No: 1992-8645 (Print), 1817-3195 (Online) -
Selective subset of relative density feature extraction algorithm for unconstrained single connected handwritten numeral recognition /
Australian Journal of Basic and Applied Sciences, Vol.8, Issue 6, pp.315-321, ISSN No: 1991-8178. -
Optimization of graded catalyst layer to enhance uniformity of current density and performance of high temperature-polymer electrolyte membrane fuel cell
The optimal use of catalyst materials is essential to improve the performance, durability and reduce the overall cost of the fuel cell. The present study is related to spatial distributions of current and overpotential for various graded catalyst structures in a high temperature-polymer electrolyte membrane fuel cell (HT-PEMFC). The effect of catalyst gradient across the catalytic layer (CL) thickness and along the channel and their combination on cell performance and catalyst utilization is investigated. The graded catalytic structure comprises two, three, or multiple layers of catalyst distribution. For a total cathode catalyst loading of 0.35 mg/cm2, higher loading near the membrane presents improved cell performance and catalyst utilization due to reduced limitations caused by oxygen and ion diffusions. However, non-uniformity in the current distribution is significantly increased. The increase in the catalyst loading along the reactant flow provides a substantially uniform current density but lower cell performance. The synergy of varying catalytic profiles across the CL thickness and along the cathode flow direction is investigated. The results emphasize the importance of a rational design of cathode structure and mathematical functions as a strategic tool for functional grading of a CL towards improved uniform current distribution and catalyst utilization. 2021 Hydrogen Energy Publications LLC -
Spatial analysis of CO poisoning in high temperature polymer electrolyte membrane fuel cells
The improved tolerance of the High Temperature-Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) to CO allows the use of reformate as an anode feed. However, the presence of several per cent of CO in the reformate, which is inevitable particularly in on-board reformation in automobiles, which otherwise demands complex systems to keep the CO level very low, will significantly lower the cell performance, especially when the HT-PEMFC is operated at 160 C or below. In this study, a three-dimensional, non-isothermal numerical model is developed and applied to a single straight-channel HT-PEMFC geometry. The model is validated against the experimental data for a broad range of current densities at different CO concentration and operating temperatures. A significant spatial variation in current density distribution is observed in the membrane because the CO sorption is a spatially non-homogeneous process depending on local operating conditions and dilution of the H2 stream. To investigate the local spatial effects on HT-PEMFC operation, the model is applied to a real cell of size 49.4 cm2 with an 8-pass serpentine flow-field at the anode and the cathode. The membrane and anode catalyst layer are segmented into 5 array to investigate the spatial resolution of the polarization curves, H2 concentration, current density, and anode polarization loss. The simulation results show that the presence of CO in the anode feed reduces cell performance, however, the results reveal that uniformity in current density distribution in the membrane improves when the cell is operated in potentiostatic mode. The results are discussed in detail with the help of several line plots and multi-dimensional contours. The study also emphasizes on the importance of optimizing the reformate anode feed rate to improve cell performance. 2020 Hydrogen Energy Publications LLC -
FORMATION OF REDDY IDENTITY IN SOUTHERN KARNATAKA 1900-2000 CE
Reddy is the name of a socio-economically and politically dominant community found in Southern India. Today one of the largest single community grouping in south India in general and Andhra Pradesh in particular is Reddy community. They are generally considered traditional village headmen. They had a remarkable history since the period of shatavahanas of 2nd century BCE and the various people from this community have helped people in large way throughout the period and they are socially committed and economically enterprise. Historically the people of the Reddy community had appears some were very wealthy Landowners and Businessmen. Famous Kings, Awardees, Academics, Scientists & Civil Servants, Business Leaders & Entrepreneurs, famous Politicians, Entertainers & Film Professionals, Freedom Fighters, Activists & Philanthropists, Poets and Writers and many more. Though the community regarded their ancestors belongs Andhra Pradesh Telugu as their mother tongue, they assimilated with the regional culture of Karnataka and became proficient in Kannada language too. The community played major role in political arena and became one among the makers of modern Karnataka. Since 1900 their Political identity was expressed through political associations, Freedom movement, and backward class movement and pressurizing for establishment responsible government in Mysore region. Socially the community has been identified as an important caste in south India. The marriage ceremony is sanctified through the authorization of Brahmana, Dasayya. The community has the complex setup within itself because they are in large number. They have peculiar social practices of the appreciation of Brahmanical ideas and process of sankritization is rooted in the original beliefs of Reddy community, The Practice of bride price, widow remarriage, the Brahmin priest not invite to their marriage occasion by some sub castes and many more. The community extended its liberal attitude towards improving the status of women has resulted in arising of many women as industrialists, artists, scientists, physicians, realtors, sports persons and scholars. Economically they are committed to land and agriculture. Culturally the community has predominant followers of the Hinduism with Veerashaiva, Vaishnava and Shaktha sects as the most important faiths. Their annual pilgrimage is to the temple of Shrishaila Mallikarjuna. Yogi VemanaReddy and HemaReddy Mallama were as the legends. The Brahmanical idenitity is not observed and accepted by all denomination of Reddys. The ??Guru Paramapare also exists among the Reddy communities. Each sub caste has to pay their homage to their respective Gurus, who preside over the Matha. The festivals celebrated by the community like Bandi Devara Habba and Makkala Dyavaru are the most specific ones. It has to be accepted as liberation from some hierarchical control and assertion of a community attempting to carve a certain niche status which resulted in a form of monastic tradition or Gurupeeta tradition since the last two decade in Karnataka. Being the promoters of education and literature they established schools, colleges, training centers, hostels and study centers. They are socially advanced, economically developed, politically organized and culturally established. Thus they become influential factor in formation of social-political-economic identity in southern Karnataka. -
Investigation on the phase transformation and lattice parameters of Sn2+, Cu2+, La3+ and Ce4+ ions doped titania: characterization and solar light activity study /
International Journal For Light And Electron Optics, Vol.183, pp.496-507, ISSN No: 0030-4026. -
Microscopic, pharmacognostic and phytochemical screening of Epiphyllum oxypetalum (dc) haw leaves /
Journal of Pharmacognosy And Phytochemistry, Vol.7, Issue 6, pp.972-980, ISSN No: 2349-8234. -
-
Dynamic linkage among crude oil, exchange rates and P/E ratio: The case of India /
International Journal of Pure And Applied Mathematics, Vol.119, Issue 18, pp.1-14, ISSN No: 1314-3395. -
Polymer-nanocarbon composites: a promising strategy for enhanced performance of organic solar cells
The exigency for sustainable and clean energy resources has led to profound research in development of various generations of solar cells, aiming to control the over-exploitation of fossil fuels and subsequently limit environmental degradation. Among the fast-emerging third-generation solar cells, polymer solar cell technology has gained much consideration due to its potential for achieving economically feasible, lightweight, flexible solar energy harvesting devices. As a predominant research area, at present, the major concerns regarding polymer solar cells include improving conversion efficiency, enhancing absorption bandgap in polymers, limiting photochemical degradation, and remediating low dielectric constant. Nanocarbon materials can be effectively blended with polymers and have been widely reported to enhance the performance of polymer solar cells owing to their desirable characteristics like high electrical conductivity, mechanical strength, thermal stability, non-toxicity, large specific surface area, flexibility, and optical transparency. In this review, we briefly discuss various conjugated polymer-nanocarbon composites, including polymer/graphene derivatives, polymer/graphene quantum dots (GQD), and polymer/carbon nanotubes (CNTs), elucidating their roles in the performance enhancement of polymer solar cells (PSCs). Graphical abstract: (Figure presented.). The Author(s) 2023. -
-
A Compact Super Wideband Antenna with Controllable Dual Notch Band Capability
In this paper, a novel super wideband (SWB) antenna with dual band notch capability is designed and analyzed for wide band applications. The proposed antenna consists of a pentagonal shaped radiator, beveled-shaped partial ground plane with slot and U-shaped parasitic strips. The beveled-shaped defected ground structure with rectangular slot helps to realize wideband characteristics from 2.4 to 28.2 GHz. Independent control of the notch band's center frequency and bandwidth is achieved by using U-shaped parasitic strips. This key feature is achieved in the WiMAX (3.3 to 3.7 GHz) and WLAN (5.1 to 5.9 GHz) bands. Furthermore, it exhibits a stable radiation pattern and offers acceptable gain over the entire operating bandwidth with sharp decrease in gain at the notches. The percentage bandwidth of 169% is achieved with a bandwidth dimension ratio (BDR) of 6986. Group delay is less than 1 ns in the entire operating bandwidth except at the notch bands. The measured reflection and radiation characteristics of fabricated SWB antenna are in good agreement with the simulation results. The proposed antenna has the advantage of simple design and compact size with an overall dimension of 18 x 21 x 1.6 mm3. The performance of the proposed antenna is superior compared to reported antenna designs in terms of controllable sharp notches and size for the bandwidth achieved. 2022 IAMOT -
Single Port Multimode Reconfigurable UWB-NB Antenna for Cognitive Radio Applications
In this paper, a compact, single port, multimode reconfigurable UWB-NB antenna with a novel feeding network is presented. The proposed antenna consists of a pentagonal-shaped monopole radiator, a beveled-shaped partial defected ground plane with a rectangular slot, and a reconfigurable bypass feeding network. The antenna realizes a wideband frequency range from 2.4 to 18 GHz and four narrow band frequency ranges, 5.3 to 6.8 GHz, 6.0 to 7.6 GHz, 7.2 to 8.8 GHz and 8.4 to 11.4 GHz. The antenna provides an omnidirectional radiation pattern with gain from 2.2 to 6.2 dBi maximum at 12 GHz and voltage standing wave ratio (VSWR) ranges from 1 to 2. The fabricated antenna has an overall dimension of 181.6 mm3. Sensing and tuning ranges of the fabricated antenna shows good agreement with the simulation results. The proposed antenna has an advantage of simple design, low profile, single port excitation and omnidirectional radiation pattern making it suitable for applications such as handheld mobile cognitive radio systems. 2022 SBMO/SBMag -
Relationships between Ultrasonographic Placental Thickness in the Third Trimester and Foetal Outcomes
Poor neonatal outcomes, including low birth weight (LBW), poor APGAR scores, more NICU hospitalizations, and a higher chance to develop Pre-Eclampsia, IUGR, and Oligo Hydramnios, are all linked to thin placental thickness. While both thin and thick placentae are connected to a greater prevalence of C-sections, thick placentae are linked with a greater possibility of developing GDM and an increase in NICU hospitalizations. Objective of this research was to investigate the association between placental thickness as measured by ultrasonography in the third trimester and foetal outcome, including the relationship between placental histopathology and placental thickness. investigate the link among placental thickness, foetal outcome, and placental histology. Most newborns had fibrinoid necrosis and calcifications. Babies with Macrosomia and IUGR, respectively, were more likely to develop Syncytial knots and thickening of the vessel wall. Patients with normal placenta thickness at 36 weeks' gestation experienced fewer difficulties than those with thin or thick placentas at the same time. The study emphasizes the value of evaluating placental thickness using ultrasound in the third trimester to detect high-risk pregnancies. The study also shows that aberrant foetal and neonatal events are linked to certain placental histological characteristics, like artery wall thickening and infarctions. RJPT All right reserved.