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A Numerical Study of a TOGA-COARE Squall-Line Using a Coupled Mesoscale Atmosphere-Ocean Model

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Advances in Atmospheric Sciences 2004年第5期21卷 708-716页

作者： Sethu raman Department of Marine Earth and Atmospheric Sciences North Carolina State University Box 8208 Raleigh NC 27695-8208

An atmosphere-ocean coupled mesoscale modeling system is developed and used to investigate the interactions between a squall line and the upper ocean observed over the western Paci?c warm pool during the Tropical Ocean/Global Atmosphere Coupled Ocean and Atmosphere Response Experiment (TOGA-COARE). The modeling system is developed by coupling the Advanced Regional Prediction Sys- tem (ARPS) to the Princeton Ocean Model (POM) through precipitation and two-way exchanges of mo- mentum, heat, and moisture across the air-sea interface. The results indicate that the interaction between the squall-line and the upper ocean produced noticeable di?erences in the sensible and latent heat ?uxes, as compared to the uncoupled cases. Precipitation, which is often ignored in air-sea heat ?ux estimates, played a major role in the coupling between the mesoscale convective system and the ocean. Precipitation a?ected the air-sea interaction through both freshwater ?ux and sensible heat ?ux. The former led to the formation of a thin stable ocean layer underneath and behind the precipitating atmospheric convection. The presence of this stable layer resulted in a more signi?cant convection-induced sea surface temperature (SST) change in and behind the precipitation zone. However, convection-induced SST changes do not seem to play an important role in the intsensi?cation of the existing convective system that resulted in the SST change, as the convection quickly moved away from the region of original SST response.

关键词： air-sea interaction mesoscale modeling squall line coupled ocean-atmosphere modeling

Single Fully Differential Second Generation Current Conveyor Based Four-Quadrant Analog Multiplier Design and Its Applications

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Chinese Journal of Electronics 2020年第5期29卷 959-965页

作者： ROY Suvajit PAL Radha-raman Department of Physics and Technophysics Vidyasagar University

This manuscript presents a new fourquadrant analog multiplier using a recently reported current mode active building block, namely the Fully differential second generation current conveyor(FDCCⅡ).The proposed circuit employs single FDCCⅡ and two NMOSFETs only, thus has simple architecture. It is fully-integrable as no other external passive component has been used. Non-ideal behaviour of the reported configuration has been analysed considering current and voltage tracking errors of the FDCCⅡ. Workability of the derived multiplier is verified with PSPICE(Cadence16.6) simulations using model parameter of TSMC 0.35μm CMOS process and found to be in close agreement with theoretical anticipations. The static power consumption of the circuit is 0.107 mW. The circuit works well with good linearity(nonlinearity error ≤ 0.96%) for the input voltage range of ±0.5 V for a supply voltage of ±1 V and the output is insensitive to temperature variation. Simulation results show that the –3 dB bandwidth of the proposed multiplier is 20.67 MHz and the output referred noise√is less than 9 nV/Hz at 1 kΩ load condition. MonteCarlo analysis has also been performed for the proposed configuration. The applicability of the reported multiplier as amplitude modulator, squarer, and frequency doubler are also demonstrated.

关键词： Four-quadrant analog multiplier Fully differential second generation current conveyor (FDCCII) Amplitude modulator Squarer Frequency doubler

Metamaterials for radiative sky cooling

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National Science Review 2018年第2期5卷 132-133页

作者： Shanhui Fan Aaswath raman Ginzton Laboratory Department of Electrical Engineering Stanford University Department of Electrical and Systems Engineering University of Pennsylvania

From fundamental thermodynamic considerations,in order to convert heat to usable work,it is important to have a heat source with a temperature that is as high as possible,and to have a heat sink with a temperature that is as low as *** vast majority of energy conversion processes at the moment use our ambient surroundings on Earth itself,with a

关键词： METAMATERIALS THERMODYNAMICS

Molecular characterization and diversity analysis of bacterial communities associated with Dialeurolonga malleswaramensis （Hemiptera： Aleyrodidae） adults using 16S rDNA amplicon pyrosequencing and FISH

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Insect Science 2016年第5期23卷 704-711页

作者： Neeti Pandey raman Rajagopal Gut Biology Lab Room No 117 Department of Zoology University of Delhi Delhi 110007 India

Dialeurolonga malleswaramensis Sundararaj （Hemiptera： Aleyrodidae） is a phytophagous sap sucking insect. It infests Polyalthia longifolia, an important avenue tree of India, effective in alleviating noise pollution and having immense medicinal importance. Samples of this insect were collected from Polyalthia longifolia. The cytochrome c oxidase subunit I gene （mtCOl） helped in the molecular characterization of the insect. This study reports the bacterial diversity in D. malleswararnensis adults by high throughput 16S rDNA amplicon pyrosequencing. The major genera identified were Portiera and Arsenophonus. Other bacterial genera detected were uncultured alpha proteobacterium, Sphingopyxis and Methylobacterium. We also employed fluorescence in situ hybridization （FISH） in whole mount samples to confirm the presence of dominant endosymbionts Portiera and Arsenophonus to the bacteriocyte of D. malleswaramensis. This study concludes that combining techniques like 16S rDNA amplicon pyrosequencing and FISH reveal both dominant and rare bacteria. The data also predict the evolutionary position of this pest with respect to other whitefly species using a mitochondrial marker.

关键词： 16S rDNA amplicon pyrosequencing bacterial diversity Dialeurolongamalleswaramensis FISH mtC01

Capture the variation of the pore pressure with different geological age from seismic inversion study in the Jaisalmer sub-basin,India

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Petroleum Science 2020年第6期17卷 1556-1578页

作者： raman Chahal Saurabh Datta Gupta Department of Applied Geophysics Indian Institute of Technology(Indian School of Mines)DhanbadDhanbadJharkhand 826004India

Geoscientific evidence shows that various parameters such as compaction,buoyancy effect,hydrocarbon maturation,gas effect and tectonic activities control the pore pressure of sub-surface *** controlled geoscientific data in the tectonically active areas is significantly useful for robust estimation of pre-drill pore *** reservoir which is tectonically complex and pore pressure is changing frequently that circumference motivated us to conduct this *** changes in pore pressure have been captured from the fine-scale to the broad scale in the Jaisalmer *** pressure variation has been distinctly observed in pre-and post-Jurassic age based on the current ***-stack seismic inversion study was conducted to capturing the variation of pore *** of low-frequency spectrum and integrated interval velocity model provided a detailed feature of pore pressure in each compartment of the study *** pressure estimated from well log data was correlated with seismic inversion based *** on the current study one well has been proposed where pore pressure was estimated and two distinguished trends are identified in the study *** approaches of the current study were analysed thoroughly and it will be highly useful in complex reservoir condition where pore pressure varies frequently.

关键词： Pore pressure Seismic inversion Clastic and carbonate reservoir

Artificially Generated Facial Images for Gender Classification Using Deep Learning

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Computer Systems Science & Engineering 2023年第2期44卷 1341-1355页

作者： Valliappan raman Khaled ELKarazle Patrick Then Coimbatore Institute of Technology Coimbatore641014India Swinburne University of Technology Kuching95530Malaysia

Given the current expansion of the computer visionﬁeld,several appli-cations that rely on extracting biometric information like facial gender for access control,security or marketing purposes are becoming more common.A typical gender classiﬁer requires many training samples to learn as many distinguishable features as ***,collecting facial images from individuals is usually a sensitive task,and it might violate either an individual's privacy or a speciﬁc data privacy *** order to bridge the gap between privacy and the need for many facial images for deep learning training,an artiﬁcially generated dataset of facial images is *** acquire a pre-trained Style-Generative Adversar-ial Networks(StyleGAN)generator and use it to create a dataset of facial *** label the images according to the observed gender using a set of criteria that differentiate the facial features of males and females *** use this manually-labelled dataset to train three facial gender classiﬁers,a custom-designed network,and two pre-trained networks based on the Visual Geometry Group designs(VGG16)and(VGG19).We cross-validate these three classiﬁers on two separate datasets containing labelled images of actual *** testing,we use the UTKFace and the Kaggle gender *** experimental results suggest that using a set of artiﬁcial images for training produces a comparable performance with accuracies similar to existing state-of-the-art methods,which uses actual images of *** average classiﬁcation accuracy of each classiﬁer is between 94%and 95%,which is similar to existing proposed methods.

关键词： Facial recognition data collection facial images generative adversarial networks facial gender estimation

A reliable knowledge processing framework for combustion science using foundation models

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Energy and AI 2024年第2期16卷 396-416页

作者： Vansh Sharma Venkat raman Department of Aerospace Engineering University of MichiganAnn Arbor48109-2102MIUSA

This research explores the integration of large language models (LLMs) into scientific data assimilation, focusing on combustion science as a case study. Leveraging foundational models integrated with Retrieval-Augmented Generation (RAG) framework, the study introduces an approach to process diverse combustion research data, spanning experimental studies, simulations, and literature. The multifaceted nature of combustion research emphasizes the critical role of knowledge processing in navigating and extracting valuable information from a vast and diverse pool of sources. The developed approach minimizes computational and economic expenses while optimizing data privacy and accuracy. It incorporates prompt engineering and offline open-source LLMs, offering user autonomy in selecting base models. The study provides a thorough examination of text segmentation strategies, conducts comparative studies between LLMs, and explores various optimized prompts to demonstrate the effectiveness of the framework. By incorporating an external vector database, the framework outperforms a conventional LLM in generating accurate responses and constructing robust arguments. Additionally, the study delves into the investigation of optimized prompt templates for the purpose of efficient extraction of scientific literature. Furthermore, we present a targeted scaling study to quantify the algorithmic performance of the framework as the number of prompt tokens increases. The research addresses concerns related to hallucinations and false research articles by introducing a custom workflow developed with a detection algorithm to filter out inaccuracies. Despite identified areas for improvement, the framework consistently delivers accurate domain-specific responses with minimal human oversight. The prompt-agnostic approach introduced holds promise for future improvements. The study underscores the significance of integrating LLMs and knowledge processing techniques in scientific research, provi

关键词： Large language models(LLM) Foundation models Combustion Knowledge processing Retrieval-augmented generation(RAG)

Key Management Using Chebyshev Polynomials for Mobile Ad Hoc Networks

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China Communications 2017年第11期14卷 237-246页

作者： K.R.Ramkumar raman Singh Chitkara University Chandigarh - Patiala National Highways (NH 64)Patiala - 140401 Punjab India Thapar University Patiala- 147004 Punjab India

A dedicated key server cannot be instituted to manage keys for MANETs since they are dynamic and unstable. The Lagrange's polynomial and curve fitting are being used to implement hierarchical key management for Mobile Ad hoc Networks(MANETs). The polynomial interpolation by Lagrange and curve fitting requires high computational efforts for higher order polynomials and moreover they are susceptible to Runge's phenomenon. The Chebyshev polynomials are secure, accurate, and stable and there is no limit to the degree of the polynomials. The distributed key management is a big challenge in these time varying networks. In this work, the Chebyshev polynomials are used to perform key management and tested in various conditions. The secret key shares generation, symmetric key construction and key distribution by using Chebyshev polynomials are the main elements of this projected work. The significance property of Chebyshev polynomials is its recursive nature. The mobile nodes usually have less computational power and less memory, the key management by using Chebyshev polynomials reduces the burden of mobile nodes to implement the overall system.

关键词： chebyshev polynomials interpolation secret sharing key management

Thermodynamic Modeling as a Strategy for Casting High Alloy Steels

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Journal of Iron and Steel Research International 2009年第5期16卷 29-31页

作者： Peri Reddy V S raman Sankaranarayanan Department of Metallurgical and Materials Engineering National Institute of Technology

Strategies based on thermodynamic calculations can be used to overcome the problems associated with oxides encountered in steel plant operations, which can lead to certain difficulties in the process such as clogging of submerged entry nozzle during continuous casting. Approaches to producing high alloy steels by continuous casting have been taken. One of the strategies to avoid the oxidation of chromium is to add a small amount of other elements （subject to other constraints）, which do not cause subsequent problems. The problem has been studied using the Thermo-CalcR software, with related databases; and the results obtained for different process conditions or generic compositions have been presented.

关键词： alloy steel continuous casting clogging slag thermodynamic modeling