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Using physics to extend the range of machine learning models for an aerodynamic, hydraulic and combusting system: The toy model concept

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能源与人工智能(英文) 2021年第4期6卷 54-70页

作者： indranil brahma Robert Jennings Bradley Freid Bucknell University United States

Machine learning models used for energy conversion system optimization cannot extrapolate outside the bounds of training data and often produce physically unrealistic results when making predictions in regions of sparse training *** toy model concept introduced in this work allows machine learning models to extrapolate to some extent and also reduces the possibility of physically unrealistic *** uses physics to shrink the model input(feature space)of data-based models,so that extrapolations in the data-based feature space tend to become interpolations in the physics-based(toy variable)feature *** physics-based model can be any model or experiment that can shrink the feature space without affecting interpolation and is termed a‘toy model’because it does not need to be accurate or make predictions of *** concept has been applied to model experimental data obtained from three complex systems:*** forces on a spinning and vibrating baseball with inclined axis of rotation(toy model:CFD model),*** turbine efficiency(toy model:PIV images of flow through stationary blades),and *** generated engine emissions(toy model:system-level 1-D model).All extrapolations were converted into interpolations for the first two systems while a 75%conversion was achieved for the emission *** engine toy model produced 736,281 possible feature spaces from which one unique feature space was chosen for every prediction based on agreement between different machine learning *** is shown that the ability of the toy variables to reorganize the data is important,while their accuracy is relatively *** toy model concept was demonstrated to work with neural networks and regression,and can be used to increase model robustness or reduce training data requirements.

关键词： Physics-Based Machine Learning Extrapolation Feature Selection Feature Engineering Engines Turbines

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A review on the current status of Fe-Al based ferritic lightweight steel

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Defence Technology（防务技术） 2023年第8期26卷 1-22页

作者： Shivkumar Khaple brahma Raju Golla V.V.Satya Prasad Defence Metallurgical Research Laboratory HyderabadIndia Metallurgical and Materials Engineering Department National Institute of TechnologyWarangalIndia

There is an ever-growing demand for lightweighting of steel for structural applications,particularly for automobile and transportation *** is mainly to improve the fuel efficiency,reduce the CO_(2) emissions and cater the increased passenger ***,the main focus is to reduce the density of the steel structure without affecting other *** can be achieved by down-gauging of the conventional steel by replacing the steel with higher strength,however,it is limited by dent resistance and ***,the novel idea is to reduce the density of the steel *** is well-known that addition of Al to steel reduces the density of the *** 1wt% of Al addition to steel can reduce the density by 1.3%,decreases the elastic modulus by 2% and it improves the strength by about 40 *** is a new class of low-density/lightweight steel with addition of about 6-9 wt% Al to *** of higher than 9 wt%of Al in steel leads to embrittlement issues due to ordering and environmental *** disordered Fe-Al lightweight steels have raised considerable interest due to their low-density,high ductility,costeffectiveness and feasibility for bulk *** low-density steels are envisaged in the development of an advanced lightweight ground transportation system,huge structures and also for certain defence applications and in thermal power plants.

关键词： Low-density steels Disordered FeeAl Thermo-mechanical processing Microstructure Properties Structure-property correlation

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Non-spherical aluminum nanoparticles fabricated using picosecond laser ablation

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International Journal of Minerals,Metallurgy and Materials 2020年第7期27卷 980-986页

作者： A.brahma Swamulu S.Venugopal Rao G.Krishna Podagatlapalli Department of Physics Rajiv Gandhi University of Knowledge TechnologiesNuzvidAndhra Pradesh 521202India Advanced Centre of Research in High Energy Materials(ACRHEM) University of HyderabadHyderabad 500046TelanganaIndia Department of Electronics&Physics Gandhi Institute of Technology and Management Institute of ScienceGandhi Institute of Technology and Management deemed to be UniversityVisakhapatnam 530045Andhra PradeshIndia

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid(chloroform,CHCl3)with^2 ps laser pulses at an input energy of^350μ*** synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at^340 *** electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of(27±3.6)*** formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al *** addition to spherical aluminum nanoparticles,triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal *** emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures(LIPSSs),which were the high spatial frequency LIPSSs(HSF-LIPSSs)since their grating period was^280 ***,coarse structures with a period of^700 nm were observed.

关键词： ablation picosecond silver polar periodic surfaces electric double layers

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Development and evaluation of robust tree biomass equations for rubber tree (Hevea brasiliensis) plantations in India

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Forest Ecosystems 2017年第3期4卷 241-250页

作者： Biplab brahma Gudeta W.Sileshi Arun Jyoti Nath Ashesh Kumar Das Department of Ecology and Environmental Science Assam University

Background： In India, rubber（Hevea brasiliensis） plantations cover -0.8 million ha of land, emphasizing its significant role in the Earth＇s carbon dynamics. Therefore, it is important to estimate the biomass stocks of plantations precisely in the context of carbon management. Previous studies in India have focused on development of allometric equations for estimating aboveground biomass（AGB） through harvesting younger trees（up to 14 yr）only or on studies with small sample sizes without assessing model bias. The objective of this study was to develop biomass estimation models for different tree components in rubber plantations and assess model predictive performance at the stand ***： A total of 67 trees were harvested from plantations of different ages（6, 15, 27 and 34 yr） in North East India and their diameter at 200 cm（D）, height and dry weights of different tree components were recorded. The data were used for evaluation of H-D and biomass estimation models at the stand ***： The Michaelis-Menten function was found to be the most appropriate model for estimating tree height among 10 commonly used H-D models. For estimation of AGB and coarse root biomass, a model that involves tree volume（i.e. D2 H） was found to provide better prediction than either D or H alone or a model that combines H, D and stand density. The estimated AGB varied from 28 Mg·ha-（-1） in 6 yr. old plantation to 169 Mg·ha-（-1） in 34 yr. old *** coarse root biomass was estimated at 4 Mg·ha-（-1） for 6 yr. old plantation and 12 Mg·ha-（-1） for 34 yr. old ***： It is concluded that models involving tree volume are more appropriate for regional level biomass estimation than simple power-law models for individual stands. We recommend that the power-law model should not be used for estimation of AGB in plantations at different growth stages because power-law parameters can be biased due to data truncation.

关键词： Aboveground biomass Data truncation Michaelis-Menten function Power-law

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Morphological phylogeny among 15 accessions of bamboos growing in Kokrajhar district of the Bodoland Territorial Area Districts,Assam

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Journal of Forestry Research 2018年第5期29卷 1379-1386页

作者： Anusriti Basumatary Sushil Kumar Middha Talambedu Usha Samik Bhattacharya Birendra Kumar brahma Arvind Kumar Goyal Centre for Bamboo Studies and Department of Biotechnology Bodoland University DBT-BIF Centre Department of BiotechnologyPG Research CentreMaharani Lakshmi Ammanni College for Women Department of Biochemistry Maharani Lakshmi Ammanni College for Women Department of Molecular Ecology Max Planck Institute of Chemical Ecology

Bamboo is nature＇s wonderful gift historically associated with the rural population of the Bodoland Territorial Area ***,indiscriminate use of the resource and the ambiguity in the identification of bamboos in the absence of flowering characters pose a potential risk to the bamboo ***,we considered revising the taxonomic positions and phylogenetic relationships among 15 tropical bamboo species using 35 key morphological descriptors（MD） to assess the reliability of vegetative characters in identifying *** phylogenetic tree constructed from the similarity matrix,derived from an unweighted pair group method of analysis（UPGMA） of the 35 MDs,marginally deviated from the conventional taxonomic positions of the bamboo *** the two varieties,one forma of Bambusa vulgaris（***,***,***） and two species of the genus Dendrocalamus（*** and ***）clustered together in a single clade,and *** was distantly placed from their *** discrepancy with the conventional classification might have ensued since only vegetative characters such as culm anatomy,culm sheath,leaf,and leaf sheath were considered in the present *** the phylogenetic relationship among the 15 tropical bamboos（computed from exhaustive MDs）grossly corroborate the conventional taxonomic grouping,a molecular-marker-based multidisciplinary approach should resolve the remaining conflicts in bamboo identification.

关键词： Bamboo Bodoland Culm Culm-sheath Leaf-sheath Phylogenetic relationship conflict

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Absolute copy number differences of Y chromosomal genes between crossbred (Bos taurus×Bos indicus) and Indicine bulls

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Journal of Animal Science and Biotechnology 2013年第4期4卷 257-263页

作者： Ayan Mukherjee Gulshan Dass Jagan Mohanarao G Moloya Gohain Biswajit brahma Tirtha Kumar Datta Sachinandan De Animal Genomics Lab Animal Biotechnology Centre National Dairy Research Institute Department of Veterinary Biochemistry College of Veterinary Sciences & Animal Husbandry Central Agricultural University

Background： The Y chromosome in mammal is paternally inherited and harbors genes related to male fertility and spermatogenesis. The unique intra-chromosomal recombination pattern of Y chromosome and morphological difference of this chromosome between Bos taurus and Bos indicus make it an ideal model for studying structural variation, especially in crossbred （Bos taurus x Bos indicus） bulls. Copy Number Variation （CNV） is a type of genomic structural variation that gives information complementary to SNP data. The purpose of this study was to find out copy number differences of four Y chromosomal spermatogenesis-related candidate genes in genomic DNA of crossbred and purebred Indicine bulls. Result： Four Y chromosomal candidate genes of spermatogenesis namely, sex determining gene on Ychromosome （SRY）, DEAD box po/ypeptide 3-Y chromosome （DDX3 Y）, Ubiquidn specific peptidase 9, Y-linked （ usPgY）, testis-specific protein on Y chromosome （TSPY） were evaluated. Absolute copy numbers of Y chromosomal genes were determined by standard curve-based quantitative real time PCR. Copy numbers of SRYand TSPYgenes per unit amount of genomic DNA are higher in crossbred than Indicine bulls. However, no difference was observed in DDX3Yand usPgYgene copy numbers between two groups. Conclusion： The present study demonstrates that the structural organization of Y chromosomes differs between crossbred and Indicine bulls which are reproductively healthy as observed from analysis of semen attributes. The absolute copy numbers of SRY and TSPY genes in unit mass of genomic DNA of crossbred bulls are significantly higher than Indicine bulls. No alteration in absolute copies ofDDX3Yand usPgYgene was found between the genome of crossbred and Indicine bulls. This study suggests that the DDX3Yand USPgYare likely to be single copy genes in the genome of crossbred and Indicine bulls and variation in Y chromosome length between crossbred and Indicine bulls may be due to the copy number variation of

关键词： Absolute copy SRY DDX3Y usPgY TSPY Crossbred

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Estimation of the Effect of Anisotropy on Young’s Moduli and Poisson’s Ratios of Sedimentary Rocks Using Core Samples in Western and Central Part of Tripura, India

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International Journal of Geosciences 2014年第2期5卷 184-195页

作者： Jwngsar brahma Anirbid Sircar Pandit Deendayal Petroleum University Gandhinagar Raisan Village Raisan India

The velocity anisotropy parameters and elastic constants play a very important role to estimate Young’s modulus and Poisson’s ratios accurately. For geomechanics applications such as hydraulic fracturing design, analysis of wellbore stability and rock failure, determination of in situ stress and assessment of the response of reservoirs and surrounding rocks to changes in pore pressure and stress, Young’s modulus and Poisson’s ratios play a very important role. Four rock samples were collected from four different wells situated in study area. The ultrasonic transmission method has been used to measure P-wave, Sh-wave and Sv-wave travel times as a function of orientation and confining pressure. The five independent stiffnesses constants, Young’s moduli, Poisson’s ratios and Bulk moduli of the samples were estimated. The Poisson’s ratios ( and ) are varying as the confining pressure is changed. The axial strain is larger than the lateral strain, resulting . For shales, the Young’s modulus measured parallel to bedding E1 is usually greater than the Young’s modulus measured perpendicular to bedding E3. Through this study it has been observed that, there is a strong effect of anisotropy parameters on Young’s modulus and Poisson’s ratio.

关键词： Elastic Stiffness Shales Sandstone Sedimentary Rock Anisotropy

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Additions to the lichen flora of Assam with special reference to Astrothelium alboverrucoides,a new record to India

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Studies in Fungi 2021年第1期6卷 342-351页

作者： Daimari R Islary P brahma S Basumatary S Goswami JP Nayaka S Joseph S Department of Botany Bodoland UniversityKokrajharAssam-783370India Lichenology Laboratory CSIR-National Botanical Research InstituteLucknow-226001India

The present study enumerates the diversity of corticolous lichens from Kokrajhar district of Assam *** study records 54 species of lichens belonging to 21 genera and 14 *** of the species are crustose(44 species)and 10 are *** of the species,Astrothelium alboverrucoides is a new record to India while five species viz.,Graphis sayeri,Hemithecium croceum,Malmidea piperis,Ocellularia allosporoides and Porina belanospora are new additions to the lichen biota of *** the species,nine are endemic to *** is the dominant family and Dirinaria consimilis is frequently found in all the study *** indicates its scope for future applications in other studies related to lichens in the region.

关键词： Corticolous Enumeration Ultapani Forest range University campus

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The protective effect of Murraya koenigii leaves against carbon tetra chloride-induced hepatic damage in rats

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Journal of Coastal Life Medicine 2014年第4期 313-318页

作者： brahma Naidu Parimi Ramgopal Mopuri Balaji Meriga Department of Biochemistry S.V.U College of SciencesSri Venkateswara UniversityTirupatiAndhra PradeshIndia

Objective:To evaluate the efficacy of methanolic extract of Murraya koenigii(MMK)leaves in attenuating the hepatic damage inflicted by carbon tetrachloride(CCl_(4)),a potent oxidative stress inducer and a model ***:Rats were divided into six groups of five each:normal control group,CCl_(4)group,CCl_(4+)silymarin group,CCl_(4+)MMK group(200 mg/kg body weight),CCl_(4+)MMK group(300 mg/kg body weight)and CCl_(4+)MMK group(500 mg/kg body weight).Rats were intraperitoneally injected with 20%CCl_(4),in corn oil(1 mL/kg body weight)and MMK was orally administered for 3 *** of hepatic markers such as alanine transaminase,aspartate transaminase,alkaline phosphatase and total billirubin were *** of superoxide dismutase,catalase and glutathione peroxidase were assayed and malondialdehyde content was *** histopathological examination,liver microtome sections were prepared and observed under light ***:Oral administration of MMK had significantly reduced the activities of aspartate transaminase,alanine transaminase,alkaline phosphatase and bilirubin content in a dosedependent manner,which were elevated by CCl_(4).However,CCl_(4)-induced rise in lipid peroxidation and drop in superoxide dismutase,catalase and glutathione peroxidase activities were reversed by MMK ***,the hepatoprotective activity of MMK was supported by histopathological examination of liver microtome ***:Our biochemical and histological studies demonstrate the potential antioxidant and hepatoprotective activity of MMK and our results scientifically validate the often use of MMK leaves in food preparation and in Ayurvedic medicine in India and neighboring countries.

关键词： Murraya koenigii Hepatoprotective Carbon tetrachloride Rats Silymarin

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Optimisation of extrusion cooking conditions and characterization of rice (Oryza sativa)—Sweet potato (Ipomoea batatas) and rice-yam (Dioscorea alata) based RTE products

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Agricultural Sciences 2013年第9期4卷 12-22页

作者： Elina brahma Hazarika Anjan Borah Charu Lata Mahanta Department of Food Engineering and Technology School of Engineering Tezpur University Assam India

Extrusion cooking has been extensively used toproduce variety of foods like ready to eatbreakfast cereals, baby foods, snack foods, etc. Taking rice flour as the base ingredient, two locally available tuberous root vegetables, greater yam(Dioscoreaalata) and sweet potato (Ipomoeabatatas) were used in this study for the development of ready-to-eat breakfast products in asingle screw extruder. During extrusion cooking, the screw speeds ranged from 132 to 468 rpm and the barrel temperatures ranged from 103°C to 137°C. The extrudates were then analyzed for various physical and physicochemical properties. Optimization was done following ResponseSurface Methodology (RSM) using CentralComposite Design. Using screw speed, barrel temperature and feed composition as the three independent variables, the three responses taken were bulk density, expansion index and breaking strength. The optimized conditions wereused for developing 3 new products one of which alsocontained tomato pulp powder. The productswere analyzed for their physical, proximate, sensoryand antioxidant properties. There was significantcolour change in all the three samples as indicated by total colour change (ΔE). Texture analysis of the extrudate samples showed hardness values ranging from 28.68 N to 47.57 N. Amylose content was found to be 15.3% in rice-sweet potato extrudate, 14.7% in rice-yam extrudate and 18.2% in rice-sweet potato-tomato extrudate. The antioxidant profile of the extrudates studiedthrough DPPH (2,2-diphenyl-picryhydrazyl)scavenging activity and FRAP (ferric reducing antioxidant property) showed that the antioxidant capacity in all the 3 extrudates was very low. Rice flour incorporated with sweet potato wasjudged the best on sensory evaluation. Thestudy has shown that both sweet potato and greater yam tubers can be commercially exploited for the development of ready-to-eat (RTE) products.

关键词： Extrusion RSM RTE Physicochemical Properties

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