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Seismic analysis of structures with a fractional derivative model of viscoelastic dampers

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Earthquake Engineering and Engineering Vibration 2002年第2期1卷 251-260页

作者： Tsu-sheng Chang Mahendra p.singh Department of Engineering Science and Mechanics.Virginia polytechnic Institute and State Universigy.Blacksburg Virginia24061.USA

Viscoelastic dampers are now among some of the preferred energy dissipation devices used for passive seismic response *** evaluate the performance of structures installed with viscoelastic dampers,different analytical models have been used to characterize their dynamic force deformation *** fractional derivative models have received favorable attention as they can capture the frequency dependence of the material stiffness and damping properties observed in the tests very ***,accurate analytical procedures are needed to calculate the response of structures with such damper *** paper presents a modal analysis approach,similar to that used for the analysis of linear systems,for solving the equations of inotion with fractional derivative terms for arbitrary forcing functions such as those caused by earthquake induced ground *** uncoupled modal equations still have fractional derivatives,but can be solved by numerical or analytical *** numerical and analytical procedures are *** procedures are then used to calculate the dynamic response of a multi-degree of fleedom shear beam structure excited by ground motions. Numerical results demonstrating the response reducing effect of viscoelastic dampers are also presented.

关键词： viscoelastic damper fractioal derivative seismic response

Heliospheric Effect on Solar Activity parameters during Maximum phase of Solar Cycle 24(2012–2015)

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Research in Astronomy and Astrophysics 2024年第12期24卷 3-12页

作者： p.R.singh Upendra Kr.singh Kushwaha A.K.singh T.K.pant Department of physics University of Allahabad Department of physics Banaras Hindu University Space physics Laboratory VSSC

The time series of daily data on solar activity proxies, namely the sunspot number(SSN), sunspot area(SSA), solar radio flux(F10.7), modified coronal index(MCI), solar flare index(FI), and cosmic ray intensity(CRI), were analyzed to understand the solar activity modulations and short-term periodicities therein. Rieger-type and other short-term periods include the solar rotational period that covers the maximum activity phase period(maximum phase of solar cycle 24). The wavelet power spectra and periodogram of SSN, SSA, F10.7, MCI, FI, and CRI exhibited a significant short-term period. The heliospheric effects exist for a particular period(～27 days) and they are related to the solar activity phenomena. The cross-correlation coefficients and time lags between the CRI and solar activity parameters were estimated to be ～200, 46, 281, 39, and 47 days for SSN, SSA, F10.7, MCI, and FI respectively during the time series 2012–2015(maximum phase of solar cycle 24).

关键词： (Sun:) sunspots Sun: activity Sun: flares Sun: heliosphere Sun: rotation

poverty alleviation and resource conservation through development of cost effective technology at foot hill of Shivalik - A case study

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International Journal of Agricultural and Biological Engineering 2013年第3期6卷 34-40页

作者： R Kumar p K singh B A Langoo Division of Agricultural Engineering Sher-e-Kashmir Univeristy of Agricultural Sciences and Techonology of KashmirSrinagar(J&K)India Department of soil and water Engineering College of Technology and EngineeringUdaipur(Raj)India

The study revealed the development of cost effective technology utilized as a practical tool for treatment of seasonal torrent and addressing erosion problems and land use *** was implemented in a small agricultural watershed located in foot hill of Shivalik,India,to assess its prediction capacity of runoff,peak runoff flow and sediment *** effective technology was evaluated at the event scale by using a database of hydrological,geomorphologic and land use data collected during a two-year *** the catchment,the gullies which are small to medium in size were treated with gully plugging by erecting loose boulder check dams and erected with different species of *** types of spur were constructed with vegetative reinforcement for channelization of stream *** sediments deposited in the first year at downstream was recorded 0.09-81.0 tons,while in the second year it was reduced up to 0.07-16.7 ***,up stream sediment deposition was recorded 1.0-72.0 tons and 0.37-13.1 tons in two consecutive *** D-50 analysis of sediment deposited was carried in three different places of torrent and it was found that deposited particle size material decreased after treatment undertaken in the torrent ***,the mechanical as well as vegetative measures helped in the channelization of water course towards the central line with the tune of 10-100 m,stabilization of torrent bed and reclamation of degraded land.

关键词： Integrated watershed management mechanical measures D-50 vegetative measures

On Almost Armendariz Ring

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Algebra Colloquium 2020年第2期27卷 199-212页

作者： Om prakash Sushma singh K.p.Shum Department of Mathematics Indian Institute of Technology Patna PatnaBihar 801106India Department of Mathematics John Fulton Center The Chinese University of Hong KongShatinN.T.Hong KongChina

In this paper,we introduce the notion of an almost Armendariz ring,which is a generalization of an Armendariz ring,and discuss some of its *** has been found that every almost Armendariz ring is weak Armendariz but the converse is not *** prove that a ring R is almost Armendariz if and only if R[x]is almost *** is also shown th at if R/I is an almost Armendariz ring and I is a semicommutative ideal,then H is an almost Armendariz ***,the class of minimal non-commutative almost Armendariz rings is completely determined,up to isomorphism(minimal means having smallest cardinality).

关键词： Armendariz ring almost Armendariz ring weak Armendariz ring lower nil radical reduced ring semicommutative ring

Eocene lignites from Cambay basin, Western India： An excellent source of hydrocarbon

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Geoscience Frontiers 2016年第5期7卷 811-819页

作者： p.K.singh V.K.singh p.K.Rajak M.p.singh A.S.Naik S.V.Raju D.Mohanty Coal & Organic petrology Lab Centre of Advanced Study in Geology Banaras Hindu University Varanasi 221005 Uttar Pradesh India Research & Development Oil India Limited Duliajan Assam 786 602 India Central Institute of Mining and Fuel Research Barwa Road Dhanbad 826015 India

In the present paper lignites from the Cambay basin have been studied for their hydrocarbon *** samples were collected from three lignite fieldse Vastan, Rajpardi and Tadkeshwar, and were investigated by petrography, chemical analyses and Rock-Eval pyrolysis. The results are well comparable with the empirically derived values. The study reveals that these ‘low rank C＇ lignites are exceedingly rich in reactive macerals（huminite t liptinite） while inertinite occurs in low concentration. These high volatile lignites generally have low ash yield except in few sections. The Rock-Eval data indicates the dominance of kerogen type-III with a little bit of type-II. The study reveals that the lignites of Vastan（lower and upper seams） and Tadkeshwar upper seam are more gas-prone while Rajpardi and Tadkeshwar lower seams are oil-prone. Further, the fixed hydrocarbons are several times higher than the free hydrocarbons. The relation between TOC and fixed hydrocarbon indicates that these lignites are excellent source rock for hydrocarbon which could be obtained mainly through thermal cracking. The empirically derived values reveal a high conversion（94e96%） and high oil yield（64e66%） for these lignites.

关键词： Eocene lignites Cambay basin Rock-Eval Maceral Hydrocarbon

Effect of post Cryorolling Treatments on Microstructural and Mechanical Behaviour of Ultrafine Grained Al-Mg-Si Alloy

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Journal of Materials Science & Technology 2014年第10期30卷 998-1005页

作者： p.Nageswara rao Dharmendra singh R.Jayaganthan Department of Metallurgical and Materials Engineering Indian Institute of Technology Roorkee

To investigate the effect of post cryorolling treatments on simultaneous enhancement in strength and ductility of ultrafine grained material （UFG）, AI 6061 alloy was subjected to cryorolling followed by warm rolling （CR ＋ WR） and compared with cryorolling followed by short annealing （CR ＋ SA） at the same temperature. Transmission electron microscopy （TEM） was used to characterize the microstructural features of the processed material. The mechanical properties were investigated through Vickers hardness testing and tensile testing at room temperature. TEM, X-ray diffraction （XRD） and differential scanning calorimetry （DSC） were used to investigate the precipitation evolution in UFG material. Results indicated that the alloy subjected to CR ＋ WR has shown improved mechanical properties （114 HV, ultimate tensile strength （UTS）： 350 Mpa） as compared to that in the case of CR ＋ SA （105 HV, UTS： 285 Mpa）. The size of the precipitates observed in CR ＋ WR sample after peak ageing treatment is finer than that of peak aged CR ＋ SA sample. The UTS of peak aged CR ＋ WR sample （UTS： 390 Mpa） was found to be higher than that of peak aged CR ＋ SA sample （UTS： 355 Mpa）, without decrease in ductility.

关键词： Aluminium alloy Cryorolling Warm rolling Short annealing Mechanical properties Differential scanning calorimetry (DSC)

petrographic characteristics and paleoenvironmental history of Eocene lignites of Cambay basin, Western India

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International Journal of Coal Science & Technology 2017年第3期4卷 214-233页

作者： prakash K. singh Vijay K. singh M. p. singh p. K. Rajak Coal and Organic petrology Lab Centre of Advanced Study in Geology Banaras Hindu University Varanasi Uttar Pradesh 221005 India

Lignite samples collected from Vastan, Rajpardi and Tadkeshwar lignite mines of Cambay basin （Gujarat） were subjected to organic petrographic investigations and geochemical analyses and the data, thus generated, is used to reconstruct the paleodepositional history of these lignite sequences. The lignites of Cambay basin dominantly comprise huminite maceral group （71.6%-86.3%） followed by liptinite （10.1%-19.3%） and inertinite （3.6%-11.0%） maceral groups. The mineral matter varies from 9.0% to 20.0%. The petrography based facies model indicates that these lignites have high values of gelification index （GI） and low tissue preservation index revealing a continuous wet condition in the basin and a relatively slower rate of subsidence during the decay of organic matter. On several occasions, during the formation of seams in Tadkeshwar, Rajpardi and Vastan mines, the value of GI exceeded 10 which indicates a forest permanently flooded and the cause of pronounced degree of degradation. However, few sections in Tadkeshwar seam had relatively drier spells of environmental conditions due to fluctuation in the water table as revealed by moderately high content of inertinite macerals. This is specially indicated by the occurrence of funginite which normally thrives in the upper oxy- genated peatigenic layer and indicates prevalence of oxic conditions during plant deposition. Such conditions prevailed during a transgressive phase but there were intermittent fluvial activities also giving rise to supratidal flood plain as reflected in the form of associated carbonaceous shales in the basin.

关键词： Cambay basin Western India Lignite Maceral paleodepositional environment

Microstructures and impact toughness behavior of Al 5083 alloy processed by cryorolling and afterwards annealing

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International Journal of Minerals,Metallurgy and Materials 2013年第8期20卷 759-769页

作者： Dharmendra singh p.Nageswara Rao R.Jayaganthan Department of Metallurgical and Materials Engineering Indian Institute of Technology RoorkeeRoorkee-247667India

The influence of rolling at liquid nitrogen temperature and annealing on the microstructure and mechanical properties of Al 5083 alloy was studied in this paper. Cryorolled samples of Al 5083 show significant improvements in strength and hardness. The ultimate tensile strength increases up to 340 Mpa and 390 Mpa for the 30% and 50% cryorolled samples, respectively. The cryorolled samples, with 30% and 50% reduction, were subjected to Charpy impact testing at various temperatures from 190℃ to 100℃. It is observed that increasing the percentage of reduction of samples during cryorolling has significant effect on decreasing impact toughness at all temperatures by increasing yield strength and decreasing ductility. Annealing of samples after cryorolling shows remarkable increment in impact toughness through recovery and recrystallization. The average grain size of the 50% cryorolled sample （14 μm） after annealing at 350℃ for 1 h is found to be finer than that of the 30% cryorolled sample （25 μm）. The scanning electron microscopy （SEM） analysis of fractured surfaces shows a large-size dimpled morphology, resembling the ductile fracture mechanism in the starting material and fibrous structure with very fine dimples in cryorolled samples corresponding to the brittle fracture mechanism.

关键词： aluminum alloys cryorolling annealing microstructure impact toughness recovery recrystallization

Accuracy of preoperative CT liver volumetry in living donor hepatectomy and its clinical implications

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Hepatobiliary Surgery and Nutrition 2018年第3期7卷 167-174页

作者： Sanjay Goja Sanjay Kumar Yadav Amardeep Yadav tarun piplani Amit Rastogi prashant Bhangui Sanjiv Saigal Arvinder singh Soin Institute of Liver Transplant and Regenerative Medicine MedantaThe MedicityGurgaonDelhi(NCR)India Department of Radiology and Nuclear Medicine MedantaThe MedicityGurgaonDelhi(NCR)India

Background: An accurate preoperative volumetric assessment of donor liver is essential for successful living donor liver transplant by ensuring adequate remnant and graft recipient weight ratio (GRWR). Methods: The study cohort consisted of 744 right lobe (RL), 65 left lobe (LL) and 33 left lateral sector (LLS) grafts from July 2010 to January 2014. A semi-automated interactive commercial software called AW Volume share 6 was used for volumetry. Bland Altman plot was used for assessing the agreement between estimated graft weight (EGW) and actual graft weight (AGW). Results: There was no statistically significant difference between EGW and AGW for RL graft weight (722±134 vs. 717±126 gm;p=0.06). Although Bland Altman graph showed that 95% limits of agreement was more in LL (?164 to +110) than RL (?156 to +147) and LLS grafts (?137 to +239), CT scan significantly overestimated LL graft weight (EGW =460±118 gm vs. AGW =433±102 gm;p=0.003) and underestimated LLS graft weight (EGW =203±48 gm vs. AGW =254±49 gm;p<0.001). Conclusions: CT volumetry overestimate LL graft and underestimate LLS graft weight. This should be factored in when selecting LL graft by taking higher GRWR.

关键词： Liver transplantation graft weight CT volumetry living donor