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Numerical study on gas production via a horizontal well from hydrate reservoirs with different slope angles in the South China Sea

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Deep Underground Science and Engineering 2024年第2期3卷 171-181页

作者： Tingting Luo Jianlin Song Xiang Sun Fanbao Cheng madhusudhan bangalore narasimha murthy Yulu Chen Yi Zhao Yongchen Song School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhouChina Institute of Rock and Soil Mechanics Chinese Academy of SciencesWuhanChina Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of TechnologyDalianChina Faculty of Engineering and the Environment University of SouthamptonSouthamptonUK

It is important to study the effect of hydrate production on the physical and mechanical properties of low-permeability clayey–silty reservoirs for the largescale exploitation of hydrate reservoirs in the South China *** this study,a multiphysical-field coupling model,combined with actual exploration drilling data and the mechanical experimental data of hydrate cores in the laboratory,was established to investigate the physical and mechanical properties of low-permeability reservoirs with different slope angles during 5-year hydrate production by the depressurization method via a horizontal *** result shows that the permeability of reservoirs severely affects gas production rate,and the maximum gas production amount of a 20-m-long horizontal well can reach186.8 m3/day during the 5-year hydrate *** with smaller slope angles show higher gas production *** depressurization propagation and hydrate dissociation mainly develop along the direction parallel to the ***,the mean effective stress of reservoirs is concentrated in the near-wellbore area with the on-going hydrate production,and gradually decreases with the increase of the slope *** from the effective stress distribution law,the total reservoir settlement amount first decreases and then increases with the increase of the slope *** maximum settlement of reservoirs with a 0°slope angle is up to 3.4 m,and the displacement in the near-wellbore area is as high as2.2 m after 5 years of hydrate *** is concluded that the pore pressure drop region of low-permeability reservoirs in the South China Sea is limited,and various slope angles further lead to differences in effective stress and strain of reservoirs during hydrate production,resulting in severe uneven settlement of reservoirs.

关键词： effective stress low‐permeability reservoirs natural gas hydrate production numerical simulation settlement slope angle the South China

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Effect of laminate thickness on moisture diffusion of polymer matrix composites in artificial seawater ageing

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Frontiers of Materials Science 2012年第3期6卷 225-235页

作者： Ratna PAL H.N.narasimha murthy M.SREEJlTHz,K.R.VISHNU MAHESH M.KRISHNA IS.C.SHARMA Department of Mechanical Engineering R.V.College of EngineeringBangalore-560059KarnatakaIndia Department of P.G.Studies and Research in Industrial Chemistry Kuvempu UniversityShankaraghattaShimoga-577451KarnatakaIndia Tumkur University Tumkur-572103KarnatakaIndia

The influence of laminate thickness of polymer matrix composites on moisture diffusion in seawater immersion, as well as the resulting mechanical property degradation for composites of glass/isopolyester （G/IPE）, carbon/isopolyester （C/IPE）, glass/vinylester （G/VE） and carbon/vinylester （CNE）, was investigated in this paper. Laminates 3 and 10 mm in thickness, fabricated using the wet hand lay-up technique, were characterized for moisture absorption in artificial seawater medium, and their flexural strength and interlaminar shear strength （ILSS） degradations were studied. Moisture diffusion was observed to be anamolous to the Fick＇s law for both 3 and 10 mm thick samples in the later stage of diffusion. Moisture permeability of 10 mm thick samples was two to three order greater than that of 3 mm thick ones, while the time to moisture saturation remained unchanged. With the increase of laminate thickness, moisture saturation increased by 1.4% for CNE and 7% for GriPE. The residual flexural strength and ILSS were greater in case of 10 mm thick specimens after 200 days of exposure. SEM examination of the fractured specimens showed greater levels of fibre/matrix debonding in 10 mm thick specimens.

关键词： polymer matrix composite diffusion coefficient Fick's law degradation

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Mechanical behavior of organo-modified Indian bentonite nanoclay fiber-reinforced plastic nanocomposites

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Frontiers of Materials Science 2013年第4期7卷 396-404页

作者： N. RAGHAVENDRA H. N. narasimha murthy M. KRISHNA K. R. VISHNU MAHESH R. SRIDHAR S. FIRDOSH G. ANGADI S. C. SHARMA Center for Manufacturing and Research Technology Utilization R. V. College Campus Bangalore 560059 Karnataka India Department of Mechanical Engineering R. V. College of Engineering Bangalore 560059 Karnataka India Department of Chemistry ACS College of Engineering Bangalore 560074 Karnataka India Tumkur University Tumkur 572103 Karnataka India

The aim of the research was to examine the influence of organo-modified Indian bentonite （IB） nanoclay dispersed in vinyisster on the mechanical properties of nanoclaylvinylesterlglass nanocomposRes. Nanoclay was organically modified using cationic surfactant hexadecyltrimethylammonium bromide （HDTMA-Br） by cation exchange method and dispersed in vinylester using ultrasonication and twin screw extrusion. XRD of nanoclaylvinylester revealed exfoliaUon at 4 wt.% nanoclay indicating uniform dispersion in the polymer. DSC results showed improvement in glass transition temperature by 22.3% in 4 wt.% nanoclaylvinylester/glass when compared with that of vinylester/glass. Nanoclay/vinylester/glass with 4 wt,% nanoclay showed 29.23%, 23.84% and 60.87% improvement in ultimate tensile strength （UTS）, fiexural strength （FS） and interlaminar shear strength （ILSS） respectively when compared with those of vinylester! glass. The mode of tensile failure examined by SEM showed no agglomeration of nanoclay in 4 wt.% nanoclayNinylester/glass specimens.

关键词： Indian bentonite (IB) ultrasonication twin-screw extrusion mechanical property

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Identification and Characterization of OsWRKY72 Variant inIndica Genotypes

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Rice science 2016年第6期23卷 297-305页

作者： narasimha ashwini radha sivarajan sajeevan makarla udayakumar karaba nalkur nataraja Department of Crop Physiology University of Agricultural SciencesGandhi Krishi Vignan KendraBangaloreKarnataka 560065India

Plant WRKY transcription factors （TFs） constitute one of the largest families of proteinsinvolved in biotic and abiotic stress responses. These TFs have a conserved 60 amino acid WRKYdomain at the N-terminal and a zinc finger motif at the C-terminal. To examine the relevance ofOsWRKY72 in imparting salinity stress tolerance, two indica rice genotypes, Rasi （tolerant genotype）and Tellahamsa （susceptible genotype）, were used. In Rasi seedlings at 12 h under 100 mmol/L NaClstress, OsWRKY72 expression was up-regulated, whereas in Tellahamsa, it was highly up-regulated atlethal stress. Full-length OsWRKY72 cDNA was cloned from these two rice genotypes for furtheranalysis. We identified a variant, termed as OsWRKY72b that carries an additional sequence of 111 bpwithin the WRKY domain. Expression of OsWRKY72b was higher under salinity stress in Rasi than inTellahamsa. Disorder prediction of OsWRKY72b showed that the additional sequence in the WRKYdomain is ordered thereby maintaining the tertiary structure that might interact with the major groove ofDNA. Prediction of phosphorylation sites in OsWRKY72b indicated that a few serine residues could bethe potential phosphorylation sites. In this study, we firstly reported a OsWRKY72 variant that couldhave a role in abiotic stress responses.

关键词： Oryza sativa indica genotype OsWRKY72 gene salinity transcription factor

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Mechanical, thermal and fire nanoclay/vinylester retardation behaviours of nanocomposites

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Frontiers of Materials Science 2011年第4期5卷 401-411页

作者： K. R. VISHNU MAHESH H. N. narasimha murthy B. E. KUMARA SWAMY S. C. SHARMA R. SRIDHAR Niranjan PATTAR M. KRISHNA B. S. SHERIGARA Department of P. G. Studies and Research in Industrial Chemistry Kuvempu University Shankaraghatta Shimoga 577451 Karnataka India Department of Mechanical Engineering R. V. College of Engineering Bangalore 560059 Karnataka India Tumkur University Tumkur 572103 Karnataka India

The dispersion of montmorillonite （MMT） in vinylester for preparing nanoclay/vinylester gel coat was reported. Two sets of MMT/vinylester specimens, namely Type I and Type 2, were prepared for comparative studies. Type I specimens were prepared using ultrasonication only, and Type 2 specimens were prepared using both ultrasonication and twin-screw extrusion. According to XRD and TEM results, Type 2 specimens showed lower levels of nanoclay agglomeration and higher levels o! exfoliation. DSC results showed that the glass transition temperatures of Type 2 specimens are higher than those of Type 1 specimens. TGA results showed that the residual weight of 4 wt.% MMT/vinylester of Type 1 was 7.38%, while the corresponding value of Type 2 was 13,5%, indicating lower thermal degradation in the latter. MMTt vinylester/glass and MMT/vinylester/carbon specimens were fabricated and tested for mechanical and fire retardation behaviours. Type 2 based nanocomposite laminates showed greater values of ultimate tensile strength, flexural strength, interlaminar shear strength, impact strength, horizontal burning rate, and vertical burning rate than Type 1 based laminates. SEM images of tensile fractured surfaces revealed that Type 2 based laminates have no or less agglomeration of nanoclay than Type 1 based laminates.

关键词： twin-screw extrusion montmorillonite nanoclay nanocomposite vinylester

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Synthesis and characterization of organomodified Na-MMT using cation and anion surfactants

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中国化学前沿:英文版 2011年第2期6卷 153-158页

作者： K.R.Vishnu MAHESH H.N.narasimha murthy B.E.KUMARASWAMY N.RAGHAVENDRA R.SRIDHAR M.KRISHNA Niranjan PATTAR Ratna PAL B.S.Sherigara Department of P.G Studies and Research in Industrial Chemistry Kuvempu UniversityShankaraghattaShimoga 577451India Department of Mechanical Engineering R V College of EngineeringBangalore 560059India

The Sodium Montmorillonite(Na-MMT)is not susceptible to polymer due to its organophilic character and low basal *** primary objective of this study was to improve Na-MMT platelets separation by organically modifying it with cation and anion exchanges using Cetyl trimethyl ammonium bromide(CTAB)and Sodium dodecyl sulfate(SDS)*** spacing,presence of functional groups,Zetapotential with particle size analysis and thermal stability of the Organomodified Na-MMT(OMMT)were characterized using XRD,FTIR,zeta-potential analyzer and TGA *** basal spacing of CTAB modified OMMTincreased to 19.5Åfrom 11.0Åwhich corresponds to the basal spacing of *** SDS modified OMMT did not show any increase in the basal *** spectra of CTAB modified Na-MMT illustrated the attachment of CTAB functional groups to Na-MMT,while the same was absent in the case of SDS modified *** zeta-potential of Na-MMT shifted from–24.88 mV to 15.66 mV in the case of CTAB modified Na-MMTand 12.49 mV for SDS modified Na-MMT,indicating a greater surface potential of the modified *** TGA showed greater weight loss for CTAB modified Na-MMT than that for Na-MMT,indicating the effective Na+ion exchange with alkyl amines.

关键词： Na-MMT CTAB SDS XRD FTIR zetapotential

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Formulation of unidirectional release buccal patches of carbamazepine and study of permeation through porcine buccal mucosa

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Asian Pacific Journal of Tropical Biomedicine 2013年第12期3卷 995-1002页

作者： Parthasarathy Govindasamy Bhaskar Reddy Kesavan Jayaveera Korlakunta narasimha R.R College of Pharmacy Sri Venkateswara College of Pharmacy JNTUA

Objective:To achieve transbuccal release of carbamazepine by loading in unidirectional release mucoadhesive buccal ***:Buccal patches of carbamazepine with unidirectional drug release were prepared using hydroxypropyl methyl cellulose,polyvinyl alcohol,polyvinyl pyrrolidone and ethyl cellulose by solvent casting *** impermeable backing layer(Pidilite?Biaxially-oriented polypropylene film)of patches provided unidirectional drug *** were evaluated for thickness,mass uniformity,surface pH and folding *** formulations FA2,FA8,FA10,FBI,FB14 and FB16(folding endurance above 250)were evaluated further for swelling studies,ex vivo mucoadhesive strength,ex vivo mucoadhesion time,in vitro drug release,ex vivo permeation,accelerated stability studies and FTIR and XRD spectral ***:The ex vivo mucoadhesion time of patches ranged between 109 min(FA10)to 126 min(FB14).The ex vivo mucoadhesive force was in the range of 0.278 lo 0.479 kg/m/*** in vitro drug release studies revealed that formulation FA8 released 84%and FB16 released 99.01%of drug in140 ***:The prepared unidirectional buccal patches of carbamazepine provided a maximum drug release within specified mucoadhesion period and it indicates a potential alternative drug delivery system for systemic denvery of carbamazepine.

关键词： Buccal patches Carbamazepine Mucoadhesion Biaxially-oriented polypropylene films Porcine buccal mucosa

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Efficiency of Coir Particle Board for Acoustic &Thermal Applications

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Open Journal of Acoustics 2019年第3期9卷 39-47页

作者： M. C. Kiran B. S. Mamatha N. Anand V. Prakash narasimha murthy IPIRTI Tumkur Road Bangalore Karnataka India

Coir fibre is extracted from the husk of coconut and is used in products such as floor mats, door mats, brushes and mattresses and in many applications. Here coir fibres are used to make particle boards of densities 300, 400 and 500 kg/m3 using UF resin to determine its efficiency for interior applications like acoustic and thermal properties and also tested for Indian standard 3129. Noise Reduction Coefficient (NRC) of all the boards decreases with an increase in density. Maximum sound absorption coefficient for all three densities was found in the frequency range of 2500 to 30,000 Hz. Among three densities, 300 kg/m3 board shows the maximum absorption coefficient at frequency 3000 Hz. The thermal conductivity results of all three densities boards increase with an increase in density. Modulus of Rupture for all three densities were meeting the requirement of standard. Results reveal that particle board manufactured from coir fibre can be used for acoustic and thermal insulation applications.

关键词： Thermal Conductivity Sound Absorption Coefficient

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Optical and structural properties of highly porous shell structured Fe doped TiO_2 thin films

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Rare Metals 2014年第5期33卷 578-582页

作者： C.S.Naveen P.Raghu H.M.Mahesh K.narasimha Rao R.Rakesh Kumar A.R.Phani Department of Electronic Science Bangalore UniversityJnanabharathi Department of Instrumentation and Applied Physics Indian Institute of Science Nano-Research for Advanced Materials and Technologies (Nano-RAM Technologies)

TiO2thin films with 0.2 wt%, 0.4 wt%, 0.6wt%, and 0.8 wt% Fe were prepared on glass and silicon substrates using sol–gel spin coating technique. The optical cut-off points are increasingly red-shifted and the absorption edge is shifted over the higher wavelength region with Fe content increasing. As Fe content increases, the optical band gap decreases from 3.03 to 2.48 eV whereas the tail width increases from 0.26 to 1.43 eV. The X-ray diffraction（XRD） patterns for doped films at 0.2 wt% and0.8 wt% Fe reveal no characteristic peaks, indicating that the film is amorphous whereas undoped TiO2exhibits（101） orientation with anatase phase. Thin films of higher Fe content exhibit a homogeneous, uniform, and nanostructured highly porous shell morphology.

关键词： Fe TiO2 Porous shell Sol–gel

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