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Acta Geologica Sinica(English Edition) 2019年第1期93卷 175-182页

作者： KURTARKAR R.Sujata SARASWAT Rajeev KAITHWAR Amrata NIGAM Rajiv Micropaleontology Laboratory Geological Oceanography Division National Institute of Oceanography

Anthropogenic activities are likely to cause global warming. Global warming will affect marine productivityand thus food availability for marine organisms. Both the seawater temperature and food availability affect benthicforaminifera, the most abundant marine calcareous microorganisms. Therefore, a laboratory culture experiment wasconducted on Cymbaloporetta plana to understand the coupled effect of temperature(25°C, 27°C, 30°C) and food(102±5,203±9, 305±14, 407±18, 508±23 diatom cells). At all temperatures, growth increased with increase in food. The specimenssubjected to 27°C temperature attained the maximum growth and those subjected to 25°C were the smallest. All specimensfed with 508±23 cells reproduced, 0 irrespective of temperature. Of all the specimens without food, 40% at 27°C and 20% at25°C reproduced, whereas specimens subjected to 30°C did not reproduce. The 100% rate of reproduction at 27°C suggeststhat it is the optimum temperature for growth and reproduction. All the specimens at 30°C and without additional food,died, whereas at 25°C and 27°C, the mortality rate was 80% and 60%, respectively. The limited growth and reproductionwith decreasing food clearly indicates that food availability also controls the growth and reproduction of shallow waterbenthic foraminifer C. plana. Therefore, warming coupled with decreasing productivity is likely to severely affect thegrowth and abundance of shallow water benthic foraminifera.

关键词： Cymbaloporetta plana culture experiment temperature food reproduction

Linkage between Seasonal Insolation Gradient in the Tropical Northern Hemisphere and the Sea Surface Salinity of the Equatorial Indian Ocean during the Last Glacial Period

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Acta Geologica Sinica(English Edition) 2012年第5期86卷 1265-1275页

作者： Saraswat RAJEEV NIGAM Rajiv Mackensen ANDREAS Weldeab SYEE Micropaleontology Laboratory National Institute of OceanographyGoaIndia Alfred Wegner Institute for Polar and Marine Research BremerhavenGermany Department of Earth Science University of CaliforniaSanta BarbaraUSA

Paired stable oxygen isotope and Mg/Ca analyses in calcite tests of the mixed-layer-dwelling planktic foraminifer Globigerinoides ruber has been used to reconstruct equatorial Indian Oceanδ18O of seawater （δ 18Osw ） over the last ~137 thousand years. On the basis of ice-volume-correctedδ18Osw （δ18Osw-ivc ）, relative changes in sea surface salinity （SSS） have been estimated. The SSS estimates suggest three episodes of higher SSS （131-113 thousand years before present （kyr BP）, 62-58 kyr BP, and 30-24 kyr BP） within the last glacial period as compared with the present. SSS comparison between interglacial episodes reveals that the surface seawater over the core site was significantly saltier during the penultimate interglacial than the Holocene. We suggest that the evolution of a seasonal insolation gradient between the Indian monsoon areas and the equator over the investigated time interval was instrumental in shaping the strength of the Indian winter and summer monsoons that left their imprints on the equatorial Indian Ocean SSS via freshwater input and wind-induced mixing. The study shows that the insolation difference between northern latitudes and the equator during winter affects monsoon strength in the Indian region, especially during cold intervals.

关键词： oxygen isotope Mg/Ca Globigerinoides ruber salinity insolation Indian Ocean

Abundance and Ecology of Endemic Asterorotalia trispinosa from the Western Bay of Bengal: Implications for its Application as a Paleomonsoon Proxy

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Acta Geologica Sinica(English Edition) 2017年第6期91卷 2268-2282页

作者： Rajeev SARASWAT Manumalenki MANASA Thejasino SUOKHRIE Mohammad Syed SAALIM rajiv nigam Micropaleontology Laboratory CSIR-National Institute of Oceanography

A total of 97 surface sediment samples were collected from the continental shelf and slope of the western Bay of Bengal to assess the potential application of Asterorotalia trispinosa as a paleomonsoon proxy. The relative abundance of living as well as total （living and dead） A. trispinosa ranges from being absent to a maximum of-31%. The highest abundance ofA. trispinosa is close to the outfall region of the Ganga-Brahmaputra Rivers and decreases away from the river mouths. Contrary to that, A. trispinosa is rare in front of both the Cauvery and Pennar river outfall regions, in the central part of the western Bay of Bengal. The living A. trispinosa abundance is the lowest in between two major river systems, viz. Ganga-Brahmaputra-Mahanadi and Krishna-Godavari. The relative abundance of both the total and living A. trispinosa is strongly positively correlated with ambient seawater temperature, and negatively correlated with %Corg and salinity. Based on the spatial distribution, we conclude that A. trispinosa is stenohaline in nature, rather than euryhaline, and further that the increased relative abundance of A. trispinosa indicates warmer and only marginally hyposaline environment. Even though the ecological preference of A. trispinosa suggests it as a potential paleomonsoon proxy, the restricted distribution implies limited application.

关键词： Asterorotalia trispinosa ecology paleomonsoon riverine influx Bay of Bengal

Deterioration of Early Holocene coral reef due to sea level rise along west coast of India:Benthic foraminiferal testimony

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Geoscience Frontiers 2012年第5期3卷 697-705页

作者： Abhijit Mazumder rajiv nigam Pravin J.Henriques Birbal Sahni Institute of Palaeobotany 53 University RoadLucknow 226 007India National Institute of Oceanography Dona PaulaGoa 403 004India Department St.Xavier's CollegeMahapalika MargMumbai 400 001India

A total of 103 surface sediment samples collected from the water depth range of 15-3300 m along Vijaydurg-Karwar stretch of central west coast of India were analyzed for foraminiferal content. Relict benthic foraminiferal assemblage was noted within 50--135 m water depth. The relict benthic foraminiferal assemblage that includes Amphistegina, Operculina and Alveolinella in sediment samples within the water depth of 85-- 135 m indicates presence of coral reef at this depth during Early Holocene. The presence of barnacle fouling on Relict foraminifera at 60--90 m confirms the paleo-shoreline. The shallow depth zone is characterized by presence of agglutinated relict foraminifera. The agglutinated forms indicate freshwater influx, which eventually increased the sea level and subsequently deteriorated the paleo-coral reef.

关键词： Relict benthicforaminifera Early Holocene coral reefPaleo-shoreline West coast of India Sea level rise

Modeling tropical river runoff: A time dependent approach

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Research in Cold and Arid Regions 2014年第3期6卷 247-256页

作者： Rashmi nigam Sudhir nigam Sushil K. Mittal Dept. of Mathematics University Institute of Technology Rajiv Gandhi Technical UniversityBhopal India Dept. of Civil Engineering Lakshmi Narain College of Technology & ScienceBhopal India Dept. of Civil Engineering Maulana Azad National Institute of TechnologyBhopal India

Forecasting of rainfall and subsequent river runoff is important for many operational problems and applications related to hydrology. Modeling river runoff often requires rigorous mathematical analysis of vast historical data to arrive at reasonable conclusions. In this paper we have applied the stochastic method to characterize and predict river runoffofthe perennial Kulfo River in southem Ethiopia. The time series analysis based auto regressive integrated moving average （ARIMA） approach is applied to mean monthly runoff data with 10 and 20 years spans. The varying length of the input runoff data is shown to influence the forecasting efficiency of the stochastic process. Preprocessing of the runoff time series data indicated that the data do not follow a seasonal pattern. Our forecasts were made using parsimonious non seasonal ARIMA models and the results were compared to actual 10-year and 20-year mean monthly runoff data of the Kulfo River. Our results indicate that river runoff forecasts based upon the 10-year data are more accurate and efficient than the model based on the 20-year time series.

关键词： flood warning stochastic process ARIMA evaluation univariate, performance error

Management of urethral strictures and stenosis caused by the endo-urological treatment of benign prostatic hyperplasiad-a single-center experience

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Asian Journal of Urology 2023年第2期10卷 137-143页

作者： rajiv N.Kore Warana Institute of Urosurgery KolhapurIndia

Objective:Urethral stricture disease after endo-urological treatment of benign prostatic hyperplasia(BPH)is a sparsely described complication.We describe management of five categories of these strictures in this retrospective observational case series.Methods:One hundred and twenty-one patients presenting with symptoms of bladder outflow obstruction after endo-urological intervention for BPH from February 2016 to March 2019 were evaluated.Among them,76 were eligible for this study and underwent reconstructive surgery.Preoperative and postoperative assessments were done with symptom scores,uroflowmetry,ultrasound for post-void residue,and urethrogram.Any intervention during follow-up was classed as a failure.The recurrence and 95%confidence interval for recurrence percentage were calculated.Results:The following five categories of patients were identified:Bulbo-membranous(33[43.4%]),navicular fossa(21[27.6%]),penile/peno-bulbar(8[10.5%]),bladder neck stenosis(6[7.9%]),and multiple locations(8[10.5%]).The average age was 69 years(range:60-84 years).Overall average symptom score,flow rate,and post-void residue changed from 21 to 7,6 mL/s to 19 mL/s,and 210 mL to 20 mL,respectively.The average follow-up was 34 months(range:12-58 months).Overall recurrence and complication rates were 10.5%and 9.2%,respectively.The recurrence in each category was seen in 3,1,2,1,and 1 patient,respectively.Overall 95% confidence interval for recurrence percentage was 4.66-19.69.Conclusion:Urethral stricture disease is a major long-term complication of endo-urological treatment of BPH.The bulbo-membranous strictures need continence preserving approach.Navicular fossa strictures require minimally invasive and cosmetic consideration.Peno-bulbar strictures require judicious use of grafts and flaps.Bladder neck stenosis in this cohort could be treated with endoscopic measures.Multiple locations need treatment based on their sites in single-stage as far as possible.

关键词： Urethral stricture Benign prostatic hyperplasia Transurethral resection of prostate Urethroplasty Holmium laser enucleation of prostate Trans-urethral bipolar electro-enucleation Bladder neck stenosis

Provisioning Intelligent Water Wave Optimization Approach for Underwater Acoustic Wireless Sensor Networks

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Computer Systems Science & Engineering 2022年第11期43卷 625-641页

作者： M.Manikandan A.rajiv Kannan Department of Computer Science and Engineering Vidhyaa Vikas College of Engineering and TechnologyTiruchengodeNamakkalTamilnaduIndia Department of Computer Science and Engineering KSR College of Engineering(Autonomous)TiruchengodeNamakkalTamilnaduIndia

In the Acoustics channel,it is incredibly challenging to offer data transfer for time-sourced applications in an energy-efficient manner due to higher error rate and propagation delay.Subsequently,conventional re-transmission over any failure generally initiates significantly larger end-to-end delay,and therefore it is not probable for time-based services.Moreover,standard techniques without any re-transmission consume enormous energy.This investigation proposes a novel multi-hop energy-aware transmission-based intelligent water wave optimization strategy.It ensures reduced end-to-end while attaining potential amongst overall energy efficiency end-to-end packet delay.It merges a naturally inspired meta-heuristic approach with multi-hop routing for data packets to reach the destination.The appropriate design of this Meta heuristic-based energy-aware scheme consumes lesser energy than the conventional one-hop transmission strategy without re-transmission.However,there is no hop-by-hop re-transmission facilitated.The proposed model shows only lesser delay than conventional methods with re-transmission.This work facilitates extensive work to carry out the proposed model performance with the MATLAB simulation environment.The results illustrate that the model is exceptionally energyefficient with lesser packet delays.With 500 nodes,the packet delivery ratio of proposed model is 100%,average delay is reduced by 2%,total energy consumption is 8 J,average packet redundancy is 1.856,and idle energy is 6.9Mwh.The proposed model outperforms existing approaches like OSF,AOR,and DMR respectively.

关键词： Acoustic applications energy efficiency network communications underwater sensor networks meta-heuristic approach intelligent water wave optimization

Estimating the impact of antiretroviral therapy on HIV-TB co-infection:Optimal strategy prediction

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International Journal of Biomathematics 2021年第1期14卷 175-221页

作者： Tanvi rajiv Aggarwal Department of Mathematics Shaheed Rajguru College of Applied Sciences for WomenUniversity of DelhiNew Delhi-110096India Department of Mathematics Deshbandhu CollegeUniversity of DelhiNew Delhi-110019India

In this paper,a nonlinear population model for HIV-TB co-infection has been proposed.The model is incorporated with the effect of early and late initiation of HIV treatment in co-infectives already on TB treatment,on the occurrence of Immune Reconstitution Inflammatory syndrome(IRIS).A 15-dimensional(15D)mathematical model has been developed in this study.We begin with considering constant treatment rates and thereafter,proceed to time-dependent treatment rates for co-infectives as control parameters.The basic reproduction number,a threshold quantity,corresponding to each HIV and TB sub-model has been computed in case of constant controls.With constant values of control parameters,mathematical analysis shows the existence and local stability of the disease-free equilibrium point and the endemic equilibrium point for the model.Together with time-dependent parameters,an optimal control problem is introduced and solved using Pontryagin’s maximum principle with an objective to minimize the number of infectives and disease induced deaths along with the cost of treatment.Numerical simulations are performed to examine the effect of reproduction numbers on control profiles and to identify,the ideal combination of treatment strategies which provides minimum burden on a society.Numerical results imply that if both HIV and TB are endemic in the population,then in order to bring in minimum burden from the co-infection,optimal control efforts must be enforced rather than constant treatment rate.

关键词： HIV tuberculosis co-infection IRIS stability optimal control

Dynamic analysis and identification of unbalance and misalignment in a rigid rotor with two offset discs levitated by active magnetic bearings:a novel trial misalignment approach

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Propulsion and Power Research 2021年第1期10卷 58-82页

作者： Prabhat Kumar rajiv Tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahatiAssam781039India

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries,transport vehicles,and in several other applications.Excessive vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous accidents.So,there is a need for perceiving the dynamic nature and identifying the faults for the safe,smooth and effective operation of machines.This paper proposes a novel trial misalignment approach to estimate the misalignment with a similar concept as the trial unbalance in the rotor balancing.Active magnetic bearing(AMB)misalignment with the rotor has been investigated with residual misalignment and additional trial misalignment cases.Additional trial misalignments are provided in addition to the unknown misalignments of the residual misalignment case.For the execution of this methodology,the dynamic model of a four-degree-of-freedom unbalanced and misaligned rigid rotor with two offset discs supported by two active magnetic bearings has been mathematically developed.The offset discs result in the gyroscopic effect at high rotor speeds.Equations of motion of the rotor-AMB system have been derived and solved to generate the time domain rotor displacement and controlling current responses at AMB positions.A fast Fourier transform technique has been utilized to convert the time domain responses into the frequency domain for estimation of unbalance eccentricities and phases together with force-displacement and forcecurrent stiffnesses of misaligned AMBs as well as AMB's constant forces using the developed identification algorithm.Identified values of AMB's parameters for both residual and additional trial misalignment cases are evaluated to estimate the four unknown misalignments.Testing of the algorithm has also been carried out at multiple spin speeds against measurement signal noise in rotor responses and bias errors in rotor system parameters to check its effectiveness and robustness.The algorithm is found to be exhi

关键词： Misalignment Unbalance Active magnetic bearing Gyroscopic moment Fast Fourier transform Identification

Proactive Connection Recovery Strategy with Recovery Time Constraint for Survivable Elastic Optical Networks

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China Communications 2021年第9期18卷 236-248页

作者： Dinesh Kumar rajiv Kumar Neeru Sharma Department of Electronics&Communication Engineering Jaypee University of Information Technology WaknaghatSolan(HP)India

This paper presents a halfway signaling exchange shared path protection(HSE-SPP)on the backup route for a fast connection recovery strategy.In the proposed HSE-SPP,a pre-assigned intermediate node on the backup route is chosen for signaling exchange.When connection fails,source and destination nodes simultaneously generate backup connection setup messages to the pre-assigned intermediate node on the reserved backup route.At the intermediate node,signaling process occurs,and acknowledgment is generated for data transmission to the respective end nodes.Consequently,connection recovery time by applying HSE-SPP becomes very low.Simulations are performed for network parameters and results are verified with existing strategies.The average recovery time(RT),bandwidth blocking probability(BBP),bandwidth provisioning ratio(BPR),and resource overbuild(RO)ratio of HSE-SPP for ARPANET is 13.54 ms,0.18,3.02,0.55,and for dedicated path protection(DPP)are 13.20 ms,0.56,6.30,3.75 and for shared path protection(SPP)22.19 ms,0.22,3.23,0.70 respectively.Similarly,average RT,BBP,BPR and RO of HSE-SPP for COST239 are8.33 ms,0.04,1.64,0.26,and for DPP 4.23,0.47,3.50,2.04,and for SPP 11.81,0.08,1.66,0.27 respectively.Hence,results of the proposed strategy are better in terms of RT,BBP,BPR,and RO ratio.

关键词： routing and spectrum assignment halfway signaling exchange-shared path protection(HSE-SPP) dedicated path protection bandwidth blocking probability(BBP)