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Polynomial friction pendulum isolators(PFPIs)for seismic performance control of benchmark highway bridge

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Earthquake Engineering and Engineering Vibration 2017年第4期16卷 827-840页

作者： Arijit saha Pumachandra saha Sanjaya Kumar Patro School of Civil Engineering KIlT UniversityBhubaneswarOdishaIndia

The seismic response of a benchmark highway bridge isolated with passive polynomial friction pendulum isolators （PFPIs） is investigated and subjected to six bidirectional ground motion records. The benchmark study is based on a lumped mass finite-element model of the 91/5 highway overcrossing located in Southern California. The PFPI system possesses two important parameters; one is horizontal flexibility and the other is energy absorbing capacity through friction. The evaluation criteria of the benchmark bridge arc analyzed considering two parameters, time period of the isolator and coefficient of friction of the isolation surface. The results of the numerical study are compared with those obtained from the traditional friction pendulum system （FPS）. Dual design performance of the PFPI system suppressed the displacement and acceleration response of the benchmark highway bridge. The dual design hysteresis loop of the PFPI system is the main advantage over the linear hysteresis loop of the FPS. The numerical result indicates that the seismic performance of the PFPI system is better than that of the traditional FPS isolated system. Further, it is observed that variations of the isolation time period and coefficient of friction of the FPS and PFPI systems have a significant effect on the peak responses of the benchmark highway bridge.

关键词： benchmark highway bridge seismic isolation FPS PFPI evaluation criteria

Effect of tool rotational speed on the particle distribution in friction stir welding of AA6092/17.5 SiCp-T6 composite plates and its consequences on the mechanical property of the joint

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Defence Technology（防务技术） 2020年第2期16卷 381-391页

作者： Uttam Acharya Barnik saha Roy Subhash Chandra saha Department of Mechanical Engineering National Institute of Technology AgartalaBarjalaJiraniaWest Tripura799046India

This study investigates the effect of tool rotational speed(TRS)on particle distribution in nugget zone(NZ)through quantitative approach and its consequences on the mechanical property of friction stir welded joints of AA6092/17.5 SiCp-T6 composite.6 mm thick plates are welded at a constant tool tilt angle of 2°and tool traverse speed of 1 mm/s by varying the TRS at 1000 rpm,1500 rpm and 2000 rpm with a taper pin profiled *** analysis shows large quantity of uniformly shaped smaller size SiC particle with lower average particle area which are homogeneously distributed in the *** fragmentation of bigger size particles has been observed because of abrading action of the hard tool and resulting shearing effect and severe stress generation due to the rotation of *** particles occupy maximum area in the matrix compared to that of the base material(BM)due to the redistribution of broken particles as an effect of *** migration of particles towards the TMAZ-NZ transition zone has been also encountered at higher TRS(2000 rpm).The microhardness analysis depicts variation in average hardness from top to bottom of the NZ,minimum for 1500 rpm and maximum for 2000 *** impact strength at 1000 rpm and 1500 rpm remains close to that of BM(21.6 J)while 2000 rpm shows the accountable *** maximum joint efficiency has been achieved at 1500 rpm(84%)and minimum at 1000 rpm(68%)under tensile *** analysis shows mixed mode of failure for BM,1000 rpm and 1500 rpm,whereas 2000 rpm shows the brittle mode of failure.

关键词： Friction stir welding Aluminium matrix composite Tool rotational speed Particle distribution Mechanical property

New analytical exact solutions of time fractional KdV KZK equation by Kudryashov methods

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Chinese Physics B 2016年第4期25卷 30-36页

作者： S saha Ray National Institute of Technology Department of Mathematics

In this paper, new exact solutions of the time fractional KdV-Khokhlov-Zabolotskaya-Kuznetsov （KdV-KZK） equa- tion are obtained by the classical Kudryashov method and modified Kudryashov method respectively. For this purpose, the modified Riemann-Liouville derivative is used to convert the nonlinear time fractional KdV-KZK equation into the non- linear ordinary differential equation. In the present analysis, the classical Kudryashov method and modified Kudryashov method are both used successively to compute the analytical solutions of the time fractional KdV-KZK equation. As a result, new exact solutions involving the symmetrical Fibonacci function, hyperbolic function and exponential function are obtained for the first time. The methods under consideration are reliable and efficient, and can be used as an alternative to establish new exact solutions of different types of fractional differential equations arising from mathematical physics. The obtained results are exhibited graphically in order to demonstrate the efficiencies and applicabilities of these proposed methods of solving the nonlinear time fractional KdV-KZK equation.

关键词： KdV-Khokhlov-Zabolotskaya-Kuznetsov equation Kudryashov method modified Kudryashovmethod fractional complex transform modified Riemann-Liouville derivative

Probabilistic seismic design of pile-supported building structure incorporating inherent variability of subsoil and ground motion uncertainty

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Earthquake Engineering and Engineering Vibration 2023年第1期22卷 135-156页

作者： Swagata DebRoy Rajib saha Civil Engineering Department National Institute of Technology AgartalaJirania-799046Tripura(West)India

Seismic failure of structures supported on pile foundation has revealed the importance of seismic soil-foundation-structure interaction(SSFSI)for ensuring safe *** uncertainties in subsoil properties and seismic loading may lead the problem to be more *** this context,the present study attempts to assess the seismic reliability of pile foundation-supported building structure embedded in inhomogeneous clay layer considering inertial *** strength of clay and earthquake loading is considered as spatially variable uncertain parameters.A non-linear soil-pile-structure system was assumed,and Monte Carlo simulation(MCS)was adopted to obtain probabilistic response of the ***-order reliability method(FORM)is used for reliability *** study indicates significant influence of uncertain parameters on the seismic response of building ***,the influence of material and load uncertainty parameters on the probabilistic seismic response of structure designed following older version of code is higher than counterpart structure designed following recent *** based reliability analysis infers thatserviceability criterion may be the governing parameter for pile foundation ***,the study also indicates that the curvature ductility demand of pile may be considered another crucial design parameter to assess the reliability of pile foundation.

关键词： seismic soil-foundation-structure interaction pile foundation soft clay Monte Carlo simulation FORM OPENSees

Group planting of cherry (Prunus avium L.) fosters growth and tree quality is superior to conventional row planting in Germany

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Journal of Forestry Research 2018年第4期29卷 1088-1099页

作者： Somidh saha Institute for Technology Assessment and Systems Analysis (ITAS) Karlsruhe Institute of Technology (KIT) Karlstr. 11 76133 Karlsruhe Germany Institute of Forest Sciences University of Freiburg Freiburg Germany

Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings （Tilia cordata Mill.） were planted with a 1 x 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings （2475 cherries and 825 limes） were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots （10 × 10 m） were randomly established in group and row planting stand, respectively. The survival rate, stability （height to diameter ratio）, diameter, and height growth were significantly higher in group planting. In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an import

关键词： Group planting Tree growth Tree quality Interspecific competition Intraspecific competition Photosynthetically active photon flux density Total sitefactor

Lesser Himalayan sequences in Eastern Himalaya and their deformation:Implications for Paleoproterozoic tectonic activity along the northern margin of India

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Geoscience Frontiers 2013年第3期4卷 289-304页

作者： Dilip saha Geological Studies Unit Indian Statistical Institute203 B.T.RoadKolkata 700108India

Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence （LHS） of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite- slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic-Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here：（1） the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; （2） the older deformation and metamorphism relate to a Pacific type accretionary orogen wh

关键词： Garnet composition Kinematics Lesser Himalayan sequence Microstructure Paleoproterozoic Supercontinent

Combined effect of Reynolds and Grashof numbers on mixed convection in a lid-driven T-shaped cavity filled with water-Al_2O_3 nanofluid

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Journal of Hydrodynamics 2015年第5期27卷 782-794页

作者： MOJUMDER Satyajit saha Sourav saha Sumon MAMUN M.A.H. Department of Mechanical Engineering Bangladesh University of Engineering and Technology

Lid-driven mixed convection has been given immense importance due to its wide range of applications. A T-shaped cavity is introduced and pertinent parameters controlling mixed convection phenomenon are analyzed in this paper. Water-Al2O3 nanofluid is considered inside the cavity to augment heat transfer rate. Galerkin weighted residual method of finite element analysis is applied for the numerical simulations. Numerical solution is obtained for different solid volume fractions of nanofluid（？= 0- 0.15）, Grashof numbers（Gr= 0.1 ？5 000） and Reynolds numbers（Re= 0.31 ？1 000） in laminar flow regime. Special attention is given on the analysis of flow at the pure mixed convection regime. It is found that Grashof, Reynolds and Richardson numbers along with solid volume fraction of nanofluid have significant effect on heat transfer characteristics inside the cavity. Results are presented using streamline and isotherm contours along with related variation of average Nusselt numbers of the heated wall and average fluid temperature inside the cavity.

关键词： mixed convection nanofluid lid-driven T-shaped Richardson number finite element

Cosmic implications of the 12C(n, γ)13C reaction: a nuclear astrophysical perspective

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Chinese Physics C 2024年第2期48卷 171-174页

作者： Soumya saha Department of Physics Bidhan Chandra CollegeRishra31G.T.Road(East)Hooghly-712248India Department of Physics University of Calcutta92Acharya Prafulla Chandra RoadKolkata-700009India

We conducted a comprehensive study of the neutron capture cross section of 12C within the relevant astrophysical energy *** rigorous R-matrix analysis,we determined the Maxwellian-averaged cross section to be 11.98±0.25μb at kT=30 *** result is approximately four times higher than the thermal neutron capture cross section estimated in earlier studies assuming the 1/v *** implications of our findings extend to the region of inhomogeneous Big-Bang models in nuclear astrophysics,where understanding the behaviour of neutron capture cross sections plays a crucial role in elucidating the intricate processes that shaped the early universe.

关键词： reaction cross section R-matrix reaction rates spectroscopic factors

A New Line Symmetry Distance and Its Application to Data Clustering

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Journal of Computer Science & Technology 2009年第3期24卷 544-556页

作者： Sriparna saha Sanghamitra Bandyopadhyay Machine Intelligence Unit Indian Statistical InstituteKolkataIndia

In this paper, at first a new line-symmetry-based distance is proposed. The properties of the proposed distance are then elaborately described. Kd-tree-based nearest neighbor search is used to reduce the complexity of computing the proposed line-symmetry-based distance. Thereafter an evolutionary clustering technique is developed that uses the new linesymmetry-based distance measure for assigning points to different clusters. Adaptive mutation and crossover probabilities are used to accelerate the proposed clustering technique. The proposed GA with line-symmetry-distance-based （GALSD） clustering technique is able to detect any type of clusters, irrespective of their geometrical shape and overlapping nature, as long as they possess the characteristics of line symmetry. GALSD is compared with the existing well-known K-means clustering algorithm and a newly developed genetic point-symmetry-distance-based clustering technique （GAPS） for three artificial and two real-life data sets. The efficacy of the proposed line-symmetry-based distance is then shown in recognizing human face from a given image.

关键词： unsupervised classification clustering symmetry property line-symmetry-based distance Kd-tree genetic algorithm face recognition