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Journal of Materials Science & Technology 2013年第7期29卷 639-646页

作者： Anil Kumar Reddy Police Srinivas Basavaraju Durga Kumari valluri Subrahmanyam Machiraju Inorganic and Physical Chemistry Division Indian Institute of Chemical TechnologyHyderabad 500607India

Porous silica prepared by using an acrylic emulsion has been impregnated with bismuth ion resulting in Bi2Si05 species containing surface. The as-prepared materials have been characterized by X-ray diffraction spectroscopy （XRD）, X-ray photoelectron spectroscopy （XPS）, UV-Vis diffuse reflectance spectroscopy （UV-Vis DRS）, scanning electron microscopy （SEM）, energy dispersive analysis of X-ray （EDAX）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR） and N2 adsorption/desorption techniques. EDAX analysis confirms the penetration of bismuth ions into the framework of silica to form Bi2SiO5, which is substantiated by XRD. The UV-Vis DRS shows that the catalysts are optically active and XPS confirms the inclusion of bismuth into the framework of silica. FTIR spectra illustrate the formation of Bi-O-Si linkages in the porous silica framework. SEM and TEM show the spherical morphology, whereas N2 adsorption/desorption study confirms the porosity of the prepared materials. The photocatalytic activity of the material is evaluated for the degradation of isoproturon herbicide and it is found that the material is active as compared to the commercial P-25 Degussa TiO2.

关键词： Acrylic emulsion Emulsion polymerization technique Porous silica Bi2SiO5 Photocatalyfic degradation lsoproturon

Renewable energy resources, policies and gaps in BRICS countries and the global impact

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Frontiers in Energy 2019年第3期13卷 506-521页

作者： lakshmi PATHAK Kavita SHAH Institute of Environment and Sustainable Development Banaras Hindu UniversityVaranasi 221005India

This paper presents comparative yet extensive analysis of existing non-conventional renewable resources, energy policies and gaps in BRICS countries. An intelligent transformation to green economy to maintain natural resources is noted. Brazil has stable energy policies and is the leading producer of biofuels following hydropower until 2014 but supported wind and solar power development by tendering specific tariffs for energy generation from solar and wind. Russia needs improvement in its legal and regulatory framework with more incentives in energy policies. China is improving upon wind and hydropower but it needs strong policy measures to put cap on increased CO2 emissions. India needs revision in energy policy and requires extra incentives and consumer specific energy policies for research-infrastructure and energy generation technologies. South Africa requires lessons to increase renewable energy and reduce coal mining. Moreover, BRICS countries need to redefine their energy policies based upon their existing geographical, economical, societal and environmental conditions which will help in shaping global energy policies and more financial stability. This paper recognizes the potential of BRICS to reshape the global system paralleled with minimizing CO2 emissions. The concerted role of BRICS needs to be recognized as the leading contributor of global renewable capacity where the developed world is geared and busy to address the environmental issues.

关键词： BRICS CO2 emissions energy policies renewable

Biodegradation of Congo Red Azo Dye by Aspergillus spp, Isolated from Dye Contaminated Soils

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Journal of Agricultural Science and Technology(A) 2014年第5期4卷 422-434页

作者： Ravuri Jaya Madhuri Gangavarapu vijaya lakshmi Department of Applied Microbiology Sri Padmavati Mahila Visvavidyalayam Tirupati 517502 A.P. lndia

In the present study, it has been aimed to determine the non target effects of Congo red on soil enzyme activities namely amylase, protease, catalase, glucose oxidase and laccases, following the standard procedures. Further, it is also aimed to decolourize the dye effluents by using immobilized fimgal cultures namely Aspergillus spp. isolated from textile effluents and estimate the percentage of decolourization by dye decolourization assay method. The selected fungi were found efficient and dominant type in dye decolourization with the production of laccase and other enzymes. Except laccase, all the enzymes showed maximum activity at 14 days followed by declining trend at 21 days. Maximum enzyme activity was noticed with Aspergillus niger. 95% of decolourization was found within 4-24 h in sodium alginate immobilized fungal cultures compared to controls. The above results clearly indicate the efficiency of these fungi in selective bioremediation of dye contaminated sites.

关键词： Congo red Aspergillus enzyme activities decolourization immobilization.

Structural and Magnetic Properties of Cr-Co Nanoferrite Particles

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Advances in Nanoparticles 2016年第1期5卷 103-113页

作者： Mamilla lakshmi Katrapally vijaya Kumar Krishnan Thyagarajan Marri Laxman Reddy Institute of Technology & Management Dundigal Hyderabad India Department of Physics JNTU Hyderabad College of Engineering Jagtial Karimnagar India Department of Physics JNTU Anantapur College of Engineering Pulivendula Pulivendula India

Nano-crystalline CrxCoFe2–xO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ferrites were synthesized by sol-gel method. The X-ray diffraction patterns of all the samples provide information about the existence of single phase spinel structure. The SEM and TEM micrographs show the uniform particle distribution and SAED pattern represents the polycrystalline nature of the resultant ferrite nano-particles. High purity of the sample is confirmed by energy dispersive X-ray analysis. The FTIR spectra show two strong absorption bands in the range of 600 - 400 cm–1, which confirm the presence of M-O stretching band in ferrites. The magnetic properties of the synthesized samples were investigated by using vibrating sample magnetometer at room temperature. According to VSM reports the main magnetic parameters like saturation magnetization (Ms), coercivity (Hc) were found to decrease with the substitution of Cr3+ content. Possible mechanisms which are responsible for the results are scrutinized minutely in this paper.

关键词： Sol-Gel Method Magnetic Property Cr-Co Nanoferrite Particles

Study of the Dielectric Behaviour of Cr-Doped Zinc Nano Ferrites Synthesized by Sol-Gel Method

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Advances in Materials Physics and Chemistry 2016年第6期6卷 141-148页

作者： Mamilla lakshmi Katrapally vijaya Kumar Krishnan Thyagarajan Marri Laxman Reddy Institute of Technology & Management Hyderabad India Department of Physics Jawaharlal Nehru Technological University Hyderabad College of Engineering Jagtial Karimnagar India Department of Physics Jawaharlal Nehru Technological University Anantapur College of Engineering Pulivendula India

The series of Cr-Zn nano ferrites having the general composition CrxZnFe2-xO4 (0 ≤ x ≤ 0.5) have been synthesized successfully in the nanocrystalline form using the sol-gel method. The samples were sintered at 900°C for 3 hours. The effect of chromium substitution on dielectric properties of Zn-ferrites is reported in this paper. The analysis of XRD patterns revealed the formation of single phase cubic spinel structure for all the Cr-Zn ferrite samples. The FTIR spectra show two strong absorption bands in the range of 400 - 600 cm-1, which corroborate the spinel structure of the samples. The average grain size was found to be in the nanometer range and of the order of 43 - 63 nm obtained using TEM images. The lattice parameter and crystallite size decrease with increase in Cr concentration (x). The investigation on dielectric constant (ε'), dissipation factor (D) and ac conductivity (σac) was carried out at a fixed frequency 1 kHz and in the frequency range of 100 Hz to 1 MHz at room temperature using LCR meter. The plots of dielectric constant (ε') versus frequency show the normal dielectric behavior of spinel ferrites. The value of ac conductivity (σac) increases with increase in frequency for all the compositions. The appearance of the peak for each composition in the dissipation factor versus frequency curve suggests the presence of relaxing dipoles in the Cr-Zn nano ferrite samples. It is also found that the shifting of the relaxation peak towards lower frequency side with an increase in chromium content (x) is due to the strengthening of dipole-dipole interactions. The composition and frequency dependence of the dielectric constant, dielectric loss and ac-conductivity are explained based on the Koop’s two-layer model, Maxwell-Wagner polarization process, and Debye relaxation theory.

关键词： Cr-Zn Nano Ferrites Dielectric Constant Dissipation Factor AC Conductivity Dipole-Dipole Interaction

Evidence of a Third Body and Photometric Solutions of a High Temperature Marginal Contact Binary CW Aqr

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Research in Astronomy and Astrophysics 2023年第5期23卷 91-100页

作者： A.vijaya K.Sriram Department of Astronomy Osmania University 500007India

Marginal contact binary systems are an important class of binary systems in exploited by astronomers to understand various astrophysical phenomena as they bridge both semi-detached and overcontact *** studied the photometric data of CW Aqr using the JCB 1.3 m telescope(JCBT),Kepler,and TESS to understand the period variations and constrain the light curve *** noted that the period of CW Aqr is increasing with a mass transfer rate of m=7.53×10^(-8)M_(⊙)yr^(-1)from the secondary to the primary *** also ascertained cyclic deviations along with a parabolic trend in the O-C *** residuals displayed a sinusoidal trend which was fitted with an LTTE,indicating the presence of a third body with an orbital period of P_(3)~10 yr and e=*** fitted the JCBT,Kepler,and TESS photometric normalized light curves and noted the mass ratio to be q~0.32 for both contact and semi-detached *** identified a temperature difference between the primary and secondary components of~2500 *** activity signatures were found in the observed light curves which were also evident from the Hαline studies where the filled-in effect was not *** our study suggests that CW Aqr is a marginal contact binary with a low mass ratio evolving toward a semi-detached ***,it may merge if the period increases due to ongoing mass transfer accompanied by a lowering in the mass ratio and later oscillate back to the period-decreasing trend due to angular momentum loss over a few cycles of thermal relaxation oscillations followed by instability.

关键词： (stars:)binaries eclipsing-Stars-(stars:)binaries(including multiple) close

Decentralized damage diagnostic technique for tall buildings using VARMAX model

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Earthquake Engineering and Engineering Vibration 2022年第2期21卷 417-439页

作者： K.lakshmi J.Prawin CSIR-Structural Engineering Research Centre CSIR RoadChennai 600113Tamil NaduIndia

Civil infrastructure,especially buildings,are becoming more slender,tall,and multipurpose,creating a need to continuously monitor their health to ensure the safety and security of human lives and *** the majority of structural health monitoring techniques use measurements from the entire structure,in this study,an output-only damage diagnostic technique using a decentralized concept(subdomain-based)for tall buildings and employing a vector form of the autoregressive moving average with exogenous input(VARMAX)model is proposed,which offers reduced instrumentation and data handling *** other decentralized approaches,this technique predicts more than one DOF at a time so the number of subdomains required for the diagnosis of the complete structure is *** proposed subdomain-based damage diagnostic algorithm works with ambient loads and does not require any correlated numerical models since it is solely based on measured *** proposed algorithm can identify the time instant of damage,spatial location(s)and characterize the damage *** have been made to account for confounding factors such as environmental and operational variabilities separate from measurement noise to avoid false positive *** effectiveness of the proposed technique is illustrated using synthetic time history responses from a twenty-story framed structure under ambient loading and an experimental study on a ten-story framed *** numerical and experimental investigations confirm the effectiveness of the method and its robustness to environmental/operational variabilities and measurement noise.

关键词： structural health monitoring subdomain high-rise buildings shear-type buildings VARMAX model environmental and operational variability measurement noise

Adaptive Particle Swarm Optimization Data Hiding for High Security Secret Image Sharing

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Computer Systems Science & Engineering 2022年第12期43卷 931-946页

作者： S.lakshmi Narayanan Electronics and Communication Engineering Sri Ramakrishna Engineering CollegeCoimbatore641022Tamil NaduIndia

The main aim of this work is to improve the security of data hiding forsecret image sharing. The privacy and security of digital information have becomea primary concern nowadays due to the enormous usage of digital *** security and the privacy of users’ images are ensured through reversible datahiding techniques. The efficiency of the existing data hiding techniques did notprovide optimum performance with multiple end nodes. These issues are solvedby using Separable Data Hiding and Adaptive Particle Swarm Optimization(SDHAPSO) algorithm to attain optimal performance. Image encryption, dataembedding, data extraction/image recovery are the main phases of the proposedapproach. DFT is generally used to extract the transform coefficient matrix fromthe original image. DFT coefficients are in float format, which assists in transforming the image to integral format using the round function. After obtainingthe encrypted image by data-hider, additional data embedding is formulated intohigh-frequency coefficients. The proposed SDHAPSO is mainly utilized for performance improvement through optimal pixel location selection within the imagefor secret bits concealment. In addition, the secret data embedding capacityenhancement is focused on image visual quality maintenance. Hence, it isobserved from the simulation results that the proposed SDHAPSO techniqueoffers high-level security outcomes with respect to higher PSNR, security level,lesser MSE and higher correlation than existing techniques. Hence, enhancedsensitive information protection is attained, which improves the overall systemperformance.

关键词： Image sharing separable data hiding using adaptive particle swarm optimization(SDHAPSO) security access control

NDN Content Poisoning Mitigation Using Bird Swarm Optimization and Trust Value

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Intelligent Automation & Soft Computing 2023年第4期36卷 833-847页

作者： S.V.vijaya Karthik J.Arputha vijaya Selvi Department of Electronics and Communication Engineering Kings College of EngineeringPudukkottai DistrictTamilnaduIndia

Information-Centric Networking(ICN)is considered a viable strategy for regulating Internet consumption using the Internet’s underlying *** Named Data Networking(NDN)and its reference-based implementa-tion,the NDN Forwarding Daemon(NFD),are the most established ICN solu-tions,their vulnerability to the Content Poisoning Attack(CPA)is regarded as a severe threat that might dramatically impact this *** Poisoning can signiﬁcantly minimize the impact of NDN’s universal data *** veriﬁcation signatures to protect against content poisoning attacks may be imprac-tical due to the associated costs and the volume of messages sent across the net-work,resulting in high computational ***,in this research,we designed a method in NDN called Bird Swarm Optimization Algorithm-Based Content Poisoning Mitigation(BSO-Content Poisoning Mitigation Scheme).By aggregating the security information of entire routers along the full path,this sys-tem introduces the BSO to explore the secure transmission path and alter the con-tent retrieval ***,based on the determined trustworthy value of each node,the BSO-Content Poisoning Mitigation Scheme can bypass malicious routers,preventing them from disseminating illicit content in the ***-ally,the suggested technique can minimize content poisoning utilizing removing erroneous Data packets from the cache-store during the pathﬁnding *** proposed method has been subjected to extensive analysis compared with the ROM scheme and improved performance justiﬁed in several ***-Con-tent Poisoning Mitigation Scheme is more efﬁcient and faster than the ROM tech-nique in obtaining valid Data packets and resulting in a higher good cache hit ratio in a comparatively less amount of time.

关键词： Named data network content poisoning bird swarm optimization content validation fake content

Estimation of total water storage changes in India

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International Journal of Digital Earth 2021年第10期14卷 1294-1315页

作者： Arun Mondal Venkataraman lakshmi School of Earth Ocean and the Environment University of South CarolinaColumbiaSCUSA Department of Engineering Systems and Environment University of VirginiaCharlottesvilleVAUSA

Long-term droughts significantly impact surface and groundwater resources in India,however,observed changes in major river basins have not been well *** we use Standardized Precipitation Index(SPI)and Standardized Precipitation Evapotranspiration Index(SPEI)at three different time scales(24,48,and 60 months)to identify long-term droughts in India for the observed record of *** characteristics(extent,events,frequency,and intensity)are analyzed for different river basins in *** trend in the areal extent of droughts is observed in two methods with three time scales in the maximum area(63.66%)in *** use the data from the Gravity Recovery and Climate Experiment(GRACE)to estimate the changes in the terrestrial water storage(TWS)during the period *** identify that major long-term droughts in India occurred from 1966 to 1969,1972,1986-1987,and *** all-India average TWS shows a negative trend from 2002 to 2015 with prominent decline in north Indian river basins and positive trend in south Indian river *** and SPEI at longer time scales are positively associated with TWS indicating the adverse impacts of droughts on surface and groundwater resources in such a populated region.

关键词： Standardized Precipitation Index(SPI) Standardized Precipitation Evapotranspiration Index(SPEI) the Gravity Recovery and Climate Experiment(GRACE) terrestrial water storage anomaly(TWSA)