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determination of NavIC differential code biases using GPS and NavIC observations

Geodesy and Geodynamics 2020年第2期11卷 97-105页

作者： K.Siva Krishna d.venkata ratnam department of Electronics and Communication Engineering Koneru Lakshamaiah Education FoundationVaddeswaramGuntur District522502Andhra PradeshIndia

delay bias between the pseudo range code is called differential Code Bias(dCB),this is one of the main error sources to estimate the precise Total Electron Content(TEC)in *** delay biases between the dual frequency band signals in both satellite and receiver are called satellite differential code biases(SdCBs)and receiver differential code biases(RdCBs).The combined satellite and receiver dCBs lead to measure error *** and RdCBs should be removed from the Global Navigation Satellite System(GNSS)measurements *** dCB estimations of GNSS signals are important for improving GNSS user positioning accuracy in ionospheric and space weather *** Navigation with Indian Constellation(NavIC)system has been developed by India to cater to positioning,navigation,timing,and ionosphere and troposphere re mote sensing *** proposed dCB estimation algorithm is necessary to calibrate the NavIC TEC measurements for both NavIC satellites and *** this work,a Global Positioning System(GPS)-aided NavIC dCB estimation algorithm has been implemented with the help of single station GPS TEC *** data were recorded at the same location by the NavIC as well as the GPS receiver(Koneru Lakshamaiah Education Foundation,Guntur,India,16.47°N,80.61°E)for the month of September *** SdCB and RdCB estimations for NavIC satellites and receivers located at Guntur,*** maximum SdCB value of 9.2 TECU was observed for NavIC satellite pseudo range number(PRN)*** deviations of NavIC satellites were in the range of 0.53-1.11 *** NavIC RdCB was estimated to be 16 *** dCB results were validated with the Fitted Receiver Bias(FRB)*** implemented dCB estimation algorithm would be useful for improving positional accuracy of NavIC users.

关键词： GPS GNSS TEC NavIC dCB

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Ionospheric time delay corrections based on the extended single layer model over low latitude region

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Geodesy and Geodynamics 2019年第3期10卷 235-240页

作者： Sahithi Karanam d.venkata ratnam J.R.K.Kumar dabbakuti department of Electronics and Communications Engineering Koneru Lakshmaiah University

Ionospheric delay error is considered to be one of the most prominent factors impacting the Global Navigation Satellite Systems(GNSS) positioning and navigation accuracies. due to dispersive nature and anisotropic of the ionosphere above certain regions, the positioning accuracy is seriously affected when using a precision-limited model. In this paper, an attempt has been taken to estimate ionosphere-delays based on Planar Fit(PF) and Spherical Harmonic Function(SHF) models by applying the commonly used single layer Model(SLM) and an extended single layer model(ESLM) which has been explored sparsely over the region. The results show that ESLM of PF and SHF techniques performed better in estimating ionospheric delay compared to the existing SLM model. Although the performance of the ESLM approach is almost comparable to the SLM results during the quiet ionospheric conditions, the ESLM-PF and ESLMSHF models led to respective improvements of 4.66% and 7.14% over the classically used SLM model under the disturbed ionospheric conditions. In view of the uneven variability of equatorial/low latitude ionosphere above the Indian subcontinental region, the suitability of ESLM-PF and ESLM-SHF models has been emphasized and suggested for assessing its completeness and reliableness across other parts of the globe. The output of this work may be useful for high precession GNSS positioning through mitigating the ionospheric delays under quiet as well as varied ionospheric conditions across the low/equatorial latitude regions.

关键词： Global Navigation Satellite Systems(GNSS) Planar fit(PF) Spherical Harmonic Function(SHF) Extended single layer model(ESLM)

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Ionospheric forecasting model using fuzzy logic-based gradient descent method

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Geodesy and Geodynamics 2017年第5期8卷 305-310页

作者： d.venkata ratnam G.Vindhya J.R.K.Kumar dabbakuti KLEF K L University Department of ECE

Space weather phenomena cause satellite to ground or satellite to aircraft transmission outages over the VHF to L-band frequency range, particularly in the low latitude region. Global Positioning System （GPS） is primarily susceptible to this form of space weather. Faulty GPS signals are attributed to ionospheric error, which is a function of Total Electron Content （TEC）. Importantly, precise forecasts of space weather conditions and appropriate hazard observant cautions required for ionospheric space weather obser- vations are limited. In this paper, a fuzzy logic-based gradient descent method has been proposed to forecast the ionospheric TEC values. In this technique, membership functions have been tuned based on the gradient descent estimated values. The proposed algorithm has been tested with the TEC data of two geomagnetic storms in the low latitude station of KL University, Guntur, India （16.44°N, 80.62°E）. It has been found that the gradient descent method performs well and the predicted TEC values are close to the original TEC measurements.

关键词： GPSGradient descent method TEC

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Characteristics of ionospheric scintillation climatology over Indian low-latitude region during the 24th solar maximum period

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Geodesy and Geodynamics 2019年第2期10卷 110-117页

作者： K.Sahithi M.Sridhar Sarat K.Kotamraju K.Ch.Sri Kavya G.Sivavaraprasad d.venkata ratnam Ch.deepthi department of Electronics and Communication Engineering Koneru Lakshamaiah Education Foundation

The amplitude and phase of L-band satellite signals are fluctuated randomly due to small scale electron density irregularity structures in the ionosphere which result in fleeting variations, known as 'ionospheric scintillations'. The Global Navigation Satellite System(GNSS) is a profound remote sensing tool to monitor, model and forecast the ionospheric weather conditions. In this paper, the GNSS amplitude scintillation data has been analyzed during the year 2013 at Bengaluru(12.9°N, 77.59°E) and Lucknow(26.8467°N, 80.9462°E) stations to reinforce climatology of ionospheric scintillation over Indian low-latitude region. The probability of scintillation occurrence and their variations over equatorial and Equatorial Ionization Anomaly(EIA) regions in India are analyzed during various geomagnetic quiet and disturbed days, months and seasons. The annual occurrence of amplitude scintillations are mapped with the function of local time. It is observed from the experimental results that the probability of scintillations occurrences is higher over EIA region than over the equatorial region. The probability of scintillations is higher during March equinox and december solstice, and lowest during June *** of scintillations is intense during post-sunset period. The maximum percentage of scintillation occurrences at the two stations are recorded in November. Moreover, the highest percentage of scintillation occurrences took place on storm day(March 17, 2013) at the two stations. This work would be helpful for understanding the features of GNSS amplitude scintillations over Southern and Northern Indian regions. Moreover, these kinds of investigations are helpful for developing new algorithms to nowcast and forecast ionospheric scintillations over Indian Sub-continent.

关键词： GNSS Ionospheric scintillations Indian low-latitude region

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Characterization of mean stem density,fibre length and lignin from two Acacia species and their hybrid

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Journal of Forestry Research 2018年第2期29卷 540-546页

作者： Asif Javed Muhammad Seong Siang Ong Wickneswari ratnam School of Environmental and Natural Resource Sciences Faculty of Science and TechnologyUniversiti Kebangsaan department of Forestry and Range Management University of Agriculture Faisalabad

The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species *** mangium *** Acacia auriculiformis *** *** their *** insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and *** possessed a high percent of lignin content compared to *** and the Acacia ***,mean stem density of *** was higher than *** and the *** length of heartwood tissues was generally shorter than that of sapwood *** hybrid had longer fibres than the parent *** was negatively correlated with mean stem ***,the wood properties of the hybrid were superior to its parent *** significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two *** thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.

关键词： Acacia mangium × Acacia auriculiformis hybrid Fibre length Indirect selection Lignin content Mean stem density

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detecting mislabeling and identifying unique progeny in Acacia mapping population using SNP markers

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Journal of Forestry Research 2017年第6期28卷 1118-1126页

作者： Asif Javed Muhammad Mohd Zaki Abdullah Norwati Muhammad Wickneswari ratnam Faculty of Science and Technology Universiti Kebangsaan Malaysia 43600 Bangi Selangor Malaysia Forestry Biotechnology division Forest Research Institute Malaysia 52110 Kepong Selangor Darul Ehsan Malaysia department of Forestry and Range Management University of Agriculture Faisalabad Faisalabad Pakistan

Acacia hybrids offer a great potential for paper industry in Southeast Asia due to their fast growth and ability to grow on abandoned or marginal lands. Breeding Acacia hybrids with desirable traits can be achieved through marker assisted selection(MAS) breeding. To develop a MAS program requires development of linkage maps and QTL analysis. Two mapping populations were developed through interspecific hybridization for linkage mapping and QTL analysis. All seeds per pod were cultured initially to improve hybrid yield as quality and density of linkage mapping is affected by the size of the mapping population. Progenies from two mapping populations were field planted for phenotypic and genotypic evaluation at three locations in Malaysia,(1) Forest Research Institute Malaysia field station at Segamat, Johor,(2) Borneo Tree Seeds and Seedlings Supplies Sdn, Bhd.(BTS) field trial site at Bintulu, Sarawak, and(3) Asiaprima RCF field trial site at Lancang, Pahang. during field planting, mislabeling was reported at Segamat, Johor, and a similar problem was suspected for Bintulu, Sarawak. Early screening with two isozymes effectively selected hybrid progenies, and these hybrids were subsequently further confirmed by using species-specific SNPs. during field planting, clonal mislabeling was reported and later confirmed by using a small set of STMS markers. A large set of SNPs were also used to screen all ramets in both populations. A total of 65.36% mislabeled ramets were encountered in the wood density population and 60.34% in the fibre length mapping population. No interpopulation pollen contamination was detected because all ramets found their match within the same population in ***, mislabeling was detected among ramets of the same population. Mislabeled individuals were identified and grouped as they originated from 93 pods for wood density and 53 pods for fibre length mapping *** average 2 meiotically unique seeds per pod(179 seeds/93 pods) for w

关键词： Tree breeding SNP markers Mislabeling Linkage mapping Quantitative trait loci(QTL) mapping

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Cross-specific amplification of microsatellite dNA markers in Shorea platyclados

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Journal of Forestry Research 2016年第1期27卷 27-32页

作者： Asif J.Muhammad Charles H.Cannon Wickneswari ratnam department of Biological Sciences Texas Tech University Faculty of Science and Technology School of Environmental and Natural Resource SciencesUniversiti Kebangsaan Malaysia

In the megadiverse forests of Southeast Asia, hundreds of timber species are economically important but the population genetics of only a few taxa are known. Cross-specific amplification of microsatellite loci among closely related taxa could enhance our ability to study and manage previously unstudied species. We successfully utilized STMS markers in Shorea platyclados, originally developed for Shorea curtisii. The six primer pairs we tried successfully produced PCR products of expected sizes. The number of alleles observed ranged from 10 to 14 and an average of 12 alleles were detected per locus. A high expected and observed heterozygosity was observed and it ranges from 0.718 to 0.827 among all populations across all six loci tested. Microsatellite dNA markers are highly polymorphic, co-dominant, reproducible, and amenable to high throughput genetic analyses. Overall, the cross- specific amplification of microsatellite loci appears to be complicated by numerous factors. While the approach may be effective for local management and conservation ofpoorly known species, the results must be carefully interpreted.

关键词： Genetic marker systems Populationgenetics SSR Selective logging Tropical timber Capillary electrophoresis

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Midline Spinal Cord Hamartomas—A Report of Six Cases

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International Journal of Clinical Medicine 2013年第6期4卷 291-295页

作者： damera Naveen Chandra Rao Vallabhaneni Kalyan Chakravarthy Eslavath Aruna Gundala venkata ratnam diddi Ranga Rao department of Pathology Pinnamaneni Siddhartha Institute of Medical Sciences & Research Foundation Chinna Avutapalli India department of Pathology Pinnamaneni Siddhartha Institute of Medical Sciences & Research Foundation Chinna Avutapalli India.

Midline Spinal Cord Hamartomas are relatively rare and asymptomatic. These lesions may present with a tethered cord and a normal overlying skin, a skin dimple, a dermal sinus tract or dense collagen. Most patients have few or no neurological symptoms related to them. Microscopically they are composed of mature and well-differentiated ectodermal and mesodermal elements, meningothelial cells, calcification, and even urothelium. We report MRI and histologic features of midline spinal cord hamartomas in six cases.

关键词： Hamartoma Meningothelial Cells Ectodermal

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Writing the future： A theoretical justification for a uniform and universal system of currency in accounting for inflation

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Journal of Modern Accounting and Auditing 2009年第7期5卷 35-43页

作者： ratnam Alagiah School of Commerce University of South Australia Adelaide 5001 South Australia

This paper submits that the advantages gained by introducing a single currency at the domestic level, applies equally to the economy at the global level. The advantages gained are （1） a reduction of the inflation rate to one common rate （if required） amongst all states, （2） a possible reduced interest rate, （3） an expansion in investment, （4） an increase in development and trade due to the removal of uncertainty, （5） the reduction in transaction costs, and （6） the reduction in the cost of capital （Moshirian, 2004, p. 306）. A single global currency has immediate implications in accounting for inflation as it presents an opportunity for the permanent removal of problems associated with accounting for inflation. This paper addresses the phenomenon of inflation and how accounting measurement and valuation associated with inflation is removed by the introduction of a single global currency.

关键词： theoretical justification uniform and universal system inflation accounting

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Truncation and Rounding-Based Scalable Approximate Multiplier design for Computer Imaging Applications

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Computers, Materials & Continua 2022年第12期73卷 5169-5184页

作者： S.Rooban A.Yamini Naga ratnam M.V.S.Ramprasad N.Subbulakshmi R.Uma Mageswari department of Electronics and Communication Engineering Koneru Lakshmaiah Education FoundationVaddeswaramGuntur522502Andhra PradeshIndia department of EECE GITAM(Deemed to be University)VisakhapatnamAPIndia department of Electronics and Communication Engineering Francis Xavier Engineering CollegeTirunelveli627003Tamil NaduIndia 4Department of Computer Science and Engineering Vardhaman College of EngineeringShamshabadHyderabad501218TelanganaIndia

Advanced technology used for arithmetic computing application,comprises greater number of approximatemultipliers and approximate *** and Rounding-based Scalable ApproximateMultiplier(TRSAM)distinguish a variety of modes based on height(h)and truncation(t)as TRSAM(h,t)in the *** TRSAM operation produces higher absolute error in Least Significant Bit(LSB)data shift unit.A new scalable approximate multiplier approach that uses truncation and rounding TRSAM(3,7)is proposed to increase themultiplier *** the help of foremost one bit architecture,the proposed scalable approximate multiplier approach reduces the partial *** proposed approximate TRSAM multiplier architecture gives better results in terms of area,delay,and *** accuracy of 95.2%and the energy utilization of 24.6 nJ is observed in the proposed multiplier *** proposed approach shows 0.11%,0.23%,and 0.24%less Mean Absolute Relative Error(MARE)when compared with the existing approach for the input of 8-bit,16-bit,and 32-bit *** also shows 0.13%,0.19%,and 0.2%less Variance of Absolute Relative Error(VARE)when compared with the existing approach for the input of 8-bit,16-bit,and 32-bit *** proposed approach is implemented with Field-Programmable Gate Array(FPGA)and shows the delay of 3.640,6.481,12.505,22.572,and 36.893 ns for the input of 8-bit,16-bit,32-bit,64-bit,and 128-bit *** proposed approach is applied in digital filters designwhich shows the Peak-Signal-to-NoiseRatio(PSNR)of 25.05 dB and Structural Similarity Index Measure(SSIM)of 0.98 with 393 pJ energy consumptions when used in image *** proposed approach is simulated with Xilinx and MATLAB and implemented with FPGA.

关键词： Truncation rounding based scalable approximate multiplier foremost one detector field programmable gate array peak-signal-to-noise-ratio structural similarity index measure

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